Embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) have the potential to differentiate into various types of cells including skeletal muscle cells. The approach of converting ESCs/iPSCs into skeletal muscle cells offers hope for patients afflicted with the skeletal muscle diseases such as the Duchenne muscular dystrophy (DMD). Patient-derived iPSCs are an especially ideal cell source to obtain an unlimited number of myogenic cells that escape immune rejection after engraftment. Currently, there are several approaches to induce differentiation of ESCs and iPSCs to skeletal muscle. A key to the generation of skeletal muscle cells from ESCs/iPSCs is the mimicking of embryonic mesodermal induction followed by myogenic induction. Thus, current approaches of skeletal muscle cell induction of ESCs/iPSCs utilize techniques including overexpression of myogenic transcription factors such as MyoD or Pax3, using small molecules to induce mesodermal cells followed by myogenic progenitor cells, and utilizing epigenetic myogenic memory existing in muscle cell-derived iPSCs. This review summarizes the current methods used in myogenic differentiation and highlights areas of recent improvement.

Duchenne muscular dystrophy (DMD) is a genetic disease affecting approximately 1 in 3500 male live births [1]. It results in progressive degeneration of skeletal muscle causing complete paralysis, respiratory and cardiac complications, and ultimately death. Normal symptoms include the delay of motor milestones including the ability to sit and stand independently. DMD is caused by an absence of functional dystrophin protein and skeletal muscle stem cells, as well as the exhaustion of satellite cells following many rounds of muscle degeneration and regeneration [2]. The dystrophin gene is primarily responsible for connecting and maintaining the stability of the cytoskeleton of muscle fibers during contraction and relaxation. Despite the low frequency of occurrence, this disease is incurable and will cause debilitation of the muscle and eventual death in 20 to 30 year olds with recessive X-linked form of muscular dystrophy. Although there are no current treatments developed for DMD, there are several experimental therapies such as stem cell therapies.

Skeletal muscle is known to be a regenerative tissue in the body. This muscle regeneration is mediated by muscle satellite cells, a stem cell population for skeletal muscle [3, 4]. Although satellite cells exhibit some multipotential differentiation capabilities [5], their primary differentiation fate is skeletal muscle cells in normal muscle regeneration. Ex vivo expanded satellite cell-derived myoblasts can be integrated into muscle fibers following injection into damaged muscle, acting as a proof-of-concept of myoblast-mediated cell therapy for muscular dystrophies [69]. However, severe limitations exist in relation to human therapy. The number of available satellite cells or myoblasts from human biopsies is limited. In addition, the poor cell survival and low contribution of transplanted cells have hindered practical application in patients [6, 8, 9]. Human-induced pluripotent stem cells (hiPSCs) are adult cells that have been genetically reprogrammed to an embryonic stem cell- (ESC-) like state by being forced to express genes and factors important for maintaining the defining properties of ESCs. hiPSCs can be generated from a wide variety of somatic cells [10, 11]. They have the ability to self-renew and successfully turn into any type of cells. With their ability to capture genetic diversity of DMD in an accessible culture system, hiPSCs represent an attractive source for generating myogenic cells for drug screening.

The ESC/iPSC differentiation follows the steps of embryonic development. The origin of skeletal muscle precursor cells comes from the mesodermal lineage, which give rise to skeletal muscle, cardiac muscle, bone, and blood cells. Mesoderm subsequently undergoes unsegmented presomitic mesoderm followed by segmented compartments termed somites from anterior to caudal direction. Dermomyotome is an epithelial cell layer making up the dorsal part of the somite underneath the ectoderm. Dermomyotome expresses Pax3 and Pax7 and gives rise to dermis, skeletal muscle cells, endothelial cells, and vascular smooth muscle [12]. Dermomyotome also serves as a tissue for secreted signaling molecules to the neural tube, notochord, and sclerotome [13, 14]. Upon signals from the neural tube and notochord, the dorsomedial lip of dermomyotome initiates and expresses skeletal muscle-specific transcription factors such as MyoD and Myf5 to differentiate into myogenic cells termed myoblasts. Myoblasts then migrate beneath the dermomyotome to form myotome. Eventually, these myoblasts fuse with each other to form embryonic muscle fibers. ESCs/iPSCs mimic these steps toward differentiation of skeletal muscle cells. Many studies utilize methods of overexpression of muscle-related transcription factors such as MyoD or Pax3 [15], or the addition of small molecules which activate or inhibit myogenic signaling during development. Several studies show that iPSCs retain a bias to form their cell type of origin due to an epigenetic memory [1619], although other papers indicate that such epigenetic memory is erased during the reprogramming processes [2022]. Therefore, this phenomenon is not completely understood at the moment. In light of these developments, we have recently established mouse myoblast-derived iPSCs capable of unlimited expansion [23]. Our data demonstrates that these iPSCs show higher myogenic differentiation potential compared to fibroblast-derived iPSCs. Thus, myogenic precursor cells generated from human myoblast-derived iPSCs expanded ex vivo should provide an attractive cell source for DMD therapy. However, since DMD is a systemic muscle disease, systemic delivery of myoblasts needs to be established for efficient cell-based therapy.

During developmental myogenesis, presomitic mesoderm is first formed by Mesogenin1 upregulation, which is a master regulator of presomitic mesoderm [24]. Then, the paired box transcription factor Pax3 gene begins to be expressed from presomitic mesoderm to dermomyotome [25]. Following Pax3 expression, Pax7 is also expressed in the dermomyotome [26], and then Myf5 and MyoD, skeletal muscle-specific transcription factor genes, begin to be expressed in the dorsomedial lip of the dermomyotome in order to give rise to myoblasts which migrate beneath the dermomyotome to form the myotome. Subsequently, Mrf4 and Myogenin, other skeletal muscle-specific transcription factor genes, followed by skeletal muscle structural genes such as myosin heavy chain (MyHC), are expressed in the myotome for myogenic terminal differentiation (Figure 1) [27, 28]. Pax3 directly and indirectly regulates Myf5 expression in order to induce myotomal cells. Dorsal neural tube-derived Wnt proteins and floor plate cells in neural tube and notochord-derived sonic hedgehog (Shh) positively regulate myotome formation [13, 29]. Neural crest cells migrating from dorsal neural tubes are also involved in myotome formation: Migrating neural crest cells come across the dorsomedial lip of the dermomyotome, and neural crest cell-expressing Delta1 is transiently able to activate Notch1 in the dermomyotome, resulting in conversion of Pax3/7(+) myogenic progenitor cells into MyoD/Myf5(+) myotomal myoblasts [30, 31]. By contrast, bone morphogenetic proteins (BMPs) secreted from lateral plate mesoderm are a negative regulator for the myotome formation by maintaining Pax3/Pax7(+) myogenic progenitor cells [29, 32]. Pax3 also regulates cell migration of myogenic progenitor cells from ventrolateral lip of dermomyotome to the limb bud [33]. Pax3 mutant mice lack limb muscle but trunk muscle development is relatively normal [34]. Pax3/Pax7 double knockout mice display failed generation of myogenic cells, suggesting that Pax3 and Pax7 are critical for proper embryonic myogenesis [35]. Therefore, both Pax3 and Pax7 are also considered master transcription factors for the specification of myogenic progenitor cells. Importantly, MyoD was identified as the first master transcription factor for myogenic specification since MyoD is directly able to reprogram nonmuscle cell type to myogenic lineage when overexpressed [3638]. In addition, genetic ablation of MyoD family gene(s) via a homologous gene recombination technique causes severe myogenic developmental or regeneration defects [3945]. Finally, genetic ablation of combinatory MyoD family genes demonstrates that MyoD/:Myf5/:MRF4/ mice do not form any skeletal muscle during embryogenesis, indicating the essential roles in skeletal muscle development of MyoD family genes [28, 46]. It was proven that Pax3 also possesses myogenic specification capability since ectopic expression of Pax3 is sufficient to induce myogenic programs in both paraxial and lateral plate mesoderm as well as in the neural tube during chicken embryogenesis [47]. In addition, genetic ablation of Pax3 and Myf5 display complete defects of body skeletal muscle formation during mouse embryogenesis [48]. Finally, overexpression of Pax7 can convert CD45(+)Sca-1(+) hematopoietic cells into skeletal muscle cells [49]. From these notions, overexpression of myogenic master transcription factors such as MyoD or Pax3 has become the major strategy for myogenic induction in nonmuscle cells, including ES/iPSCs.

The overexpression of MyoD approach to induce myogenic cells from mESCs was first described by Dekel et al. in 1992. This has been a standard approach for the myogenic induction from pluripotent stem cells (Table 1). Ozasa et al. first utilized Tet-Off systems for MyoD overexpression in mESCs and showed desmin(+) and MyHC(+) myotubes in vitro [50]. Warren et al. transfected synthetic MyoD mRNA in to hiPSCs for 3 days, which resulted in myogenic differentiation (around 40%) with expression of myogenin and MyHC [51]. Tanaka et al. utilized a PiggyBac transposon system to overexpress MyoD in hiPSCs. The PiggyBac transposon system allows cDNAs to stably integrate into the genome for efficient gene expression. After integration, around 70 to 90% of myogenic cells were induced in hiPSC cultures within 5 days [52]. This study also utilized Miyoshi myopathy patient-derived hiPSCs for the MyoD-mediated myogenic differentiation. Miyoshi myopathy is a congenital distal myopathy caused by defective muscle membrane repair due to mutations in dysferlin gene. The patient-derived hiPSC-myogenic cells will be able to provide the opportunity for therapeutic drug screening. Abujarour et al. also established a model of patient-derived skeletal muscle cells which express NCAM, myogenin, and MyHC by doxycycline-inducible overexpression of MyoD in DMD patient-derived hiPSCs [53]. Interestingly, MyoD-induced iPSCs also showed suppression of pluripotent genes such as Nanog and a transient increase in the gene expression levels of T (Brachyury T), Pax3, and Pax7, which belong to paraxial mesodermal/myogenic progenitor genes, upstream genes of myogenesis. It is possible that low levels of MyoD activity in hiPSCs may initially suppress their pluripotent state while failing to induce myogenic programs, which may result in transient paraxial mesodermal induction. Supporting this idea, BAF60C, a SWI/SNF component that is involved in chromatin remodeling and binds to MyoD, is required to induce full myogenic program in MyoD-overexpressing hESCs [54]. Overexpression of MyoD alone in hESC can only induce some paraxial mesodermal genes such as Brachyury T, mesogenin, and Mesp1 but not myogenic genes. Co-overexpression of MyoD and BAF60C was now able to induce myogenic program but not paraxial mesodermal gene expression, indicating that there are different epigenetic landscapes between pluripotent ESCs/iPSCs and differentiating ESC/iPSCs in which MyoD is more accessible to DNA targets than those in pluripotent cells. The authors then argued that without specific chromatin modifiers, only committed cells give rise to myogenic cells by MyoD. These results strongly indicate that nuclear landscapes are important for cell homogeneity for the specific cell differentiation in ESC/iPSC cultures. Similar observations were seen in overexpression of MyoD in P19 embryonal carcinoma stem cells, which can induce paraxial mesodermal genes including Meox1, Pax3, Pax7, Six1, and Eya2 followed by muscle-specific genes. However, these MyoD-induced paraxial mesodermal genes were mediated by direct MyoD binding to their regulatory regions, which was proven by chromatin immunoprecipitation (ChIP) assays, indicating the novel role for MyoD in paraxial mesodermal cell induction [55].

hESCs/iPSCs have been differentiated into myofibers by overexpression of MyoD, and this method is considered an excellent in vitro model for human skeletal muscle diseases for muscle functional tests, therapeutic drug screening, and genetic corrections such as exon skipping and DNA editing. Shoji et al. have shown that DMD patient-derived iPSCs were used for myogenic differentiation via PiggyBac-mediated MyoD overexpression. These myogenic cells were treated with morpholinos for exon-skipping strategies for dystrophin gene correction and showed muscle functional improvement [56]. Li et al. have shown that patient-derived hiPSC gene correction by TALEN and CRISPR-Cas9 systems, and these genetically corrected hiPSCs were used for myogenic differentiation via overexpression of MyoD [57]. This work also revealed that the TALEN and CRISPR-Cas9-mediated exon 44 knock-in approach in the dystrophin gene has high efficiency in gene-editing methods for DMD patient-derived cells in which the exon 44 is missing in the genome.

Along this line of the strategy, Darabi et al. first performed overexpression of Pax3 gene, which can be activated by treatment with doxycycline in mESCs, and showed efficient induction of MyoD/Myf5(+) skeletal myoblasts in EB cultures [15]. Upon removing doxycycline, these myogenic cells underwent MyHC(+) myotubes. However, teratoma formation was observed after EB cell transplantation into cardiotoxin-injured regenerating skeletal muscle in Rag2/:C/ immunodeficient mice [15]. This indicates that myogenic cell cultures induced by Pax3 in mESCs still contain some undifferentiated cells which gave rise to teratomas. To overcome this problem, the same authors separated paraxial mesodermal cells from Pax3-induced EB cells by FACS using antibodies against cell surface markers as PDGFR(+)Flk-1() cell populations. After cell sorting, isolated Pax3-induced paraxial mesodermal cells were successfully engrafted and contributed to regenerating muscle in mdx:Rag2/:C/ DMD model immunodeficient mice without any teratoma formations. Darabi et al. also showed successful myogenic induction in mESCs and hES/iPSCs by overexpression of Pax7 [58, 59]. Pax3 and Pax7 are not only expressed in myogenic progenitor cells. They are also expressed in neural tube and neural crest cell-derived cells including a part of cardiac cell types in developmental stage, suggesting that further purification to skeletal muscle cell lineage is crucial for therapeutic applications for muscle diseases including DMD.

Taken together, overexpression of myogenic master transcription factors such as MyoD or Pax3/Pax7 is an excellent strategy for myogenic induction in hESCs and hiPSCs, which can be utilized for in vitro muscle disease models for their functional test and drug screening. However, for the safe stem cell therapy, it is essential to maintain the good cellular and genetic qualities of hESC/hiPSC-derived myogenic cells before transplantation. Therefore, random integration sites of overexpression vectors for myogenic master transcription factors and inappropriate expression control of these transgenes may diminish the safety of using these induced myogenic cells for therapeutic stem cell transplantation.

Stepwise induction protocols utilizing small molecules and growth factors have been established as alternative myogenic induction approaches and a more applicable method for therapeutic situations. As described above, during embryonic myogenesis, somites and dermomyotomes receive secreted signals such as Wnts, Notch ligands, Shh, FGF, BMP, and retinoic acid (RA) with morphogen gradients from surrounding tissues in order to induce the formation of myogenic cells (Figure 2). The canonical Wnt signaling pathway has been shown to play essential roles in the development of myogenesis. In mouse embryogenesis, Wnt1 and Wnt3a secreted from the dorsal neural tube can promote myogenic differentiation of dorsomedial dermomyotome via activation of Myf5 [31, 32, 60]. Wnt3a is able to stabilize -catenin which associates with TCF/LEF transcription factors that bind to the enhancer region of Myf5 during myogenesis [61]. Other Wnt proteins, Wnt6 and Wnt7a, which emerge from the surface ectoderm, induce MyoD [62]. BMP functions as an inhibitor of myogenesis by suppression of some myogenic gene expressions. In the lateral mesoderm, BMP4 is able to increase Pax3 expression which delays Myf5 expression in order to maintain an undifferentiated myogenic progenitor state [63]. Therefore, Wnts and BMPs regulate myogenic development by antagonizing each other for myogenic transcription factor gene expression [64, 65]. Wnt also induces Noggin expression to antagonize BMP signals in the dorsomedial lip of the dermomyotome [66]. In this region, MyoD expression level is increased, which causes myotome formation. Notch signaling plays essential roles for cell-cell communication to specify the different cells in developmental stages. During myotome formation, Notch is expressed in dermomyotome, and Notch1 and Notch2 are expressed in dorsomedial lip of dermomyotome. Delta1, a Notch ligand, is expressed in neural crest cells which transiently interact with myogenic progenitor cells in dorsomedial lip of dermomyotome via Notch1 and 2. This contact induces expression of the Myf5 or MyoD gene in the myogenic progenitor cells followed by myotome formation. The loss of function of Delta1 in the neural crest displays delaying skeletal muscle formation [67]. Knockdown of Notch genes or use of a dominant-negative form of mastermind, a Notch transcriptional coactivator, clearly shows dramatically decrease of Myf5 and MyHC(+) myogenic cells. Interestingly, induction of Notch intracellular domain (NICD), a constitutive active form of Notch, can promote myogenesis, while continuous expression of NICD prevents terminal differentiation. Taken together, transient and timely activation of Notch is crucial for myotome formation from dermomyotome [30].

Current studies for myogenic differentiation of ESCs/iPSCs have utilized supplementation with some growth factors and small molecules, which would mimic the myogenic development described above in combination with embryoid body (EB) aggregation and FACS separation of mesodermal cells (Table 2). To induce paraxial mesoderm cells from mESCs, Sakurai et al. utilized BMP4 in serum-free cultures [68]. Three days after treatment with BMP4, mESCs could be differentiated into primitive streak mesodermal-like cells, but the continuous treatment with BMP4 turned the ESCs into osteogenic cells. Therefore, they used LiCl after treatment with BMP4 to enhance Wnt signaling, which is able to induce myogenic differentiation. After treatment with LiCl, PDGFR(+) E-cadherin() paraxial mesodermal cells were sorted by FACS. These sorted cells were cultured with IGF, HGF, and FGF for two weeks in order to induce myogenic differentiation. Hwang et al. have shown that treatment with Wnt3a efficiently promotes skeletal muscle differentiation of hESCs [69]. hESCs were cultured to form EB for 9 days followed by differentiation of EBs for additional 7 days, and then PDGFR(+) cells were sorted by FACS. These PDGFR(+) cells were cultured with Wnt3a for additional 14 days. Consequently, these Wnt3a-treated cells display significantly increased myogenic transcription factors and structural proteins at both mRNA and protein levels. An interesting approach to identify key molecules that induce myogenic cells was reported by Xu et al. [70]. They utilized reporter systems in zebrafish embryos to display myogenic progenitor cell induction and myogenic differentiation in order to identify small compounds for myogenic induction. Myf5-GFP marks myogenic progenitor cells, while myosin light polypeptide 2 (mylz2)-mCherry marks terminally differentiated muscle cells. They found that a mixed cocktail containing GSK3 inhibitor, bFGF, and forskolin has the potential to induce robust myogenic induction in hiPSCs. GSK3 inhibitors act as a canonical Wnt signaling activator via stabilizing -catenin protein, which is crucial for inducing mesodermal cells. Forskolin activates adenylyl cyclase, which then stimulates cAMP signaling. cAMP response element-binding protein (CREB) is able to stimulate cell proliferation of primary myoblasts in vitro, suggesting that the forskolin-cAMP-CREB pathway may help myogenic cell expansion [71], However the precise mechanisms for CREB-mediated myogenic cell expansion remain unclear. The adenylyl cyclase signaling cascade leads to CREB activation [71]. During embryogenesis, phosphorylated CREB has been found at dorsal somite and dermomyotome. CREB gene knockout mice display significantly decreased Myf5 and MyoD expressions in myotomes. While activation of Wnt1 or Wnt7a promotes Pax3, Myf5, and MyoD expressions, inhibition of CREB eliminates these Wnt-mediated myogenic gene expressions without altering the Wnt canonical pathway, suggesting that CREB-induced myogenic activation may be mediated through noncanonical Wnt pathways. Several groups also utilized GSK3 inhibitors for inducing mesodermal cells from ESCs and iPSCs [72, 73]. These mesodermal cell-like cells were expanded by treatment with bFGF, and then ITS (insulin/transferrin/selenite) or N2 medium were used to induce myogenic differentiation. Finally, bFGF is a stimulator for myogenic cell proliferation. Caron et al. demonstrated that hESCs treated with GSK3 inhibitor, ascorbic acid, Alk5 inhibitor, dexamethasone, EGF, and insulin generated around 80% of Pax3(+) myogenic precursor cells in 10 days [74]. Treatment with SB431542, an inhibitor of Alk4, 5, and 7, PDGF, bFGF, oncostatin, and IGF was able to induce these Pax3(+) myogenic precursor cells into around 5060% of MyoD(+) myoblasts in an additional 8 days. For the final step, treatment with insulin, necrosulfonamide, an inhibitor of necrosis, oncostatin, and ascorbic acid was able to induce these myoblasts into myotubes in an additional 8 days. Importantly, the same authors utilized ESCs from human facioscapulohumeral muscular dystrophy (FSHD) to demonstrate the myogenic characterization after myogenic induction by using the protocol described above. Hosoyama et al. have shown that hESCs/iPSCs with high concentrations of bFGF and EGF in combination with cell aggregation, termed EZ spheres, efficiently give rise to myogenic cells [75]. After 6-week culture, around 4050% of cells expressed Pax7, MyoD, or myogenin. However, the authors also showed that EZ spheres included around 30% of Tuj1(+) neural cells. Therefore, the authors discussed the utilization of molecules for activation of mesodermal and myogenic signaling pathways such as BMPs and Wnts.

Taken together, it is likely that the induced cell populations from ESCs/iPSCs may contain other cell types such as neural cells or cardiac cells because neural cells share similar transcription factor gene expression with myogenic cells such as Pax3, and cardiac cells also develop from mesodermal cells. To overcome this limitation, Chal et al. treated ESCs/iPSCs with BMP4 inhibitor, which prevents ESCs/iPSCs from differentiating into lateral mesodermal cells [76, 77]. To identify what genes are involved in myogenic differentiation in vivo, they performed a microarray analysis which compared samples of dissected fragments in mouse embryos, which are able to separate tail bud, presomitic mesoderm, and somite regions. From microarray data, the authors focused on Mesogenin1 (Msgn1) and Pax3 genes. Importantly, they utilized three lineage tracing reporters, Msgn1-repV (Mesogenin1-Venus) marking posterior somitic mesoderm, Pax3-GFP marking anterior somitic mesoderm and myogenic cells, and Myog-repV (Myogenin-Venus) marking differentiated myocytes, allowing the authors to readily detect different differentiation stages during ESC/iPSC cultures. Treatment with GSK3 inhibitors and then BMP inhibitors in ESC cultures induced Msgn1(+) somitic mesoderm with 45 to 65% efficiencies, Pax3(+) anterior somitic mesoderm with 30 to 50% efficiencies, and myogenin(+) myogenic cells with 25 to 30% efficiencies. Furthermore, the authors examined differentiation of mdx ESCs into skeletal muscle cells and revealed abnormal branching myofibers. Current protocols were also published and described more details for hiPSC differentiation [77].

Some nonmuscle cell populations such as mesoangioblasts have the potential to differentiate into skeletal muscle [6]. Mesoangioblasts were originally isolated from embryonic mouse dorsal aorta as vessel-associated pericyte-like cells, which have the ability to differentiate into a myogenic lineage in vitro and in vivo [6, 78]. Mesoangioblasts possess an advantage for the clinical cell-based treatment because they can be injected through an intra-arterial route to systemically deliver cells, which is crucial for therapeutic cell transplantation for muscular dystrophies [79]. Tedesco et al. successfully generated human iPSC-derived mesoangioblast-like stem/progenitor cells called HIDEMs by stepwise protocols without FACS sorting [80, 81]. They displayed similar gene expression profiles as embryonic mesoangioblasts. However, HIDEMs do not spontaneously differentiate into skeletal muscle cells, and thus, the authors utilized overexpression of MyoD to differentiate into skeletal muscle cells. Similar to mesoangioblasts, HIDEM-derived myogenic cells could be delivered to injured muscle via intramuscular and intra-arterial routes. Furthermore, HIDEMs have been generated from hiPSCs derived from limb-girdle muscular dystrophy (LGMD) type 2D patients and used for gene correction and cell transplantation experiments for the potential therapeutic application.

Myogenic precursor cells derived from ESCs/iPSCs by various methods may contain nonmuscle cells. Therefore, further purification is mandatory for therapeutic applications. Barberi et al. isolated CD73(+) multipotent mesenchymal precursor cells from hESCs by FACS, and these cells underwent differentiation into fat, cartilage, bone, and skeletal muscle cells [82]. Barberi et al. also demonstrated that hESCs cultured on OP9 stroma cells generated around 5% of CD73(+) adult mesenchymal stem cell-like cells [83]. After FACS, these CD73(+) mesenchymal stem cell-like cells were cultured with ITS medium for 4 weeks and then gave rise to NCAM(+) myogenic cells. After FACS sorting, these NCAM(+) myogenic cells were purified by FACS and transplanted into immunodeficient mice to show their myogenic contribution to regenerating muscle.

It has been shown that many genes are associated with myogenesis. In addition, exhaustive analysis, such as microarray, RNA-seq, and single cell RNA-seq supplies much gene information in many different stages. Chal et al. showed key signaling factors by microarray from presomitic somite, somite, and tail bud cells [76]. They found that initial Wnt signaling has important roles for somite differentiation. Furthermore, mapping differentiated hESCs by single cell RNA-seq analysis is useful to characterize each differentiated stage [84].

As shown above, cell sorting of mesodermal progenitor cells, mesenchymal precursor cells, or myogenic cells is a powerful tool to obtain pure myogenic populations from differentiated pluripotent cells. Sakurai et al. have been able to induce PDGFR(+)Flk-1() mesodermal progenitor cells by FACS followed by myogenic differentiation [85]. Chang et al. and Mizuno et al. have been able to sort SMC-2.6(+) myogenic cells from mouse ESCs/iPSCs [86, 87]. These SMC-2.6(+) myogenic cells were successfully engrafted into mouse regenerating skeletal muscle. However, this SMC-2.6 antibody only recognizes mouse myogenic cells but not human myogenic cells [86, 88]. Therefore, Borchin et al. have shown that hiPSC-derived myogenic cells differentiated into c-met(+)CXCR4(+)ACHR(+) cells, displaying that over 95% of sorted cells are Pax7(+) myogenic cells [72]. Taken together, current myogenic induction protocols utilizing small molecules and growth factors, with or without myogenic transcription factors, have been largely improved in the last 5 years. It is crucial to standardize the induction protocols in the near future to obtain sufficient myogenic cell conversion from pluripotent stem cells.

Recent work demonstrated that cells inherit a stable genetic program partly through various epigenetic marks, such as DNA methylation and histone modifications. This cellular memory needs to be erased during genetic reprogramming, and the cellular program reverted to that of an earlier developmental stage [16, 22, 89]. However, iPSCs retaining an epigenetic memory of their origin can readily differentiate into their original tissues [1619, 90100]. This phenomenon becomes a double-edged sword for the reprogramming process since the retention of epigenetic memory may reduce the quality of pluripotency while increasing the differentiation efficiency into their original tissues. DNA methylation levels are relatively low in the pluripotent stem cells compared to the high levels of DNA methylation seen in somatic cells [101]. Global DNA demethylation is required for the reprogramming process [102]. In the context of these observations, recent work demonstrates that activation-induced cytidine deaminase AID/AICDA contributing to the DNA demethylation can stabilize stem-cell phenotypes by removing epigenetic memory of pluripotent genes. This directly deaminates 5-methylcytosine in concert with base-excision repair to exchange cytosine in genomic DNA [103]. MicroRNA-155 has been identified as a key player for the retention of epigenetic memory during in vitro differentiation of hematopoietic progenitor cell-derived iPSCs toward hematopoietic progenitors [104]. iPSCs that maintained high levels of miR-155 expression tend to differentiate into the original somatic population more efficiently.

Recently, we generated murine skeletal muscle cell-derived iPSCs (myoblast-derived iPSCs) [23] and compared the efficiency of differentiation of myogenic progenitor cells between myoblast-derived iPSCs and fibroblast-derived iPSCs. After EB cultures, more satellite cell/myogenic progenitor cell differentiation occurred in myoblast-derived iPSCs than that in fibroblast-derived-iPSCs (unpublished observation and Figure 3), suggesting that myoblast-derived iPSCs are potential myogenic and satellite cell sources for DMD and other muscular dystrophy therapies (Figure 4). We also noticed that MyoD gene suppression by Oct4 is required for reprogramming in myoblasts to produce iPSCs (Figure 3) [23]. During overexpression of Oct4, Oct4 first binds to the Oct4 consensus sequence located in two MyoD enhancers (a core enhancer and distal regulatory region) [105107] preceding occupancy at the promoter in myoblasts in order to suppress MyoD gene expression. Interestingly, Oct4 binding to the MyoD core enhancer allows for establishment of a bivalent state in MyoD promoter as a poised state, marked by active (H3K4me3) and repressive (H3K27me3) modifications in fibroblasts, one of the characteristics of stem cells (Figure 3) [23, 108]. It should be investigated whether the similar bivalent state is also established in Oct4-expressing myoblasts during reprogramming process from myoblasts to pluripotent stem cells. It remains to be elucidated whether Oct4-mediated myogenic repression only relies on repression of MyoD expression or is just a general phenomenon of functional antagonism between Oct4 and MyoD on activation of muscle genes. Nevertheless, myoblast-derived iPSCs will enable us to produce an unlimited number of myogenic cells, including satellite cells that could form the basis of novel treatments for DMD and other muscular dystrophies (Figure 4).

There are pros and cons of transgene-free small molecule-mediated myogenic induction protocols. In the transgene-mediated induction protocols, integration of the transgene in the host genome may lead to risk for insertional mutagenesis. To circumvent this issue, there is an obvious advantage for transgene-free induction protocols. Some key molecules such as Wnt, FGF, and BMP have used signaling pathways to induce myogenic differentiation of ES/iPSCs. However, these molecules are also involved in induction of other types of cell lineages, which makes it difficult for ES/iPSCs to induce pure myogenic cell populations in vitro. By contrast, transgene-mediated myogenic induction is able to dictate desired specific cell lineages. In any case, it is necessary to intensively investigate these myogenic induction protocols for the efficient and safe stem cell therapy for patients.

For skeletal muscle diseases, patient-derived hiPSCs, which possess the ability to differentiate into myogenic progenitor cells followed by myotubes, can be a useful tool for drug screening and personalized medicine in clinical practice. However, there are still limitations for utilizing hiPSC-derived myogenic cells for regenerative medicine. For cell-based transplantation therapies such as a clinical situation, animal-free defined medium is essential for stem cell culture and skeletal muscle cell differentiation. Therefore, such animal-free defined medium needs to be established for optimal myogenic differentiation from hiPSCs. Gene correction in DMD patient iPSCs by TALENs and CRISPR-Cas9 systems are promising therapeutic approaches for stem cell transplantation. However, there are still problems for DNA-editing-mediated stem cell therapy such as safety and efficacy. Since iPSC-derived differentiated myotubes do not proliferate, they are not suited for cell transplantation. Therefore, a proper culture method needs to be established for hiPSCs in order to maintain cells in proliferating the myogenic precursor cell stage in vitro in order to expand cells to large quantities of transplantable cells for DMD and other muscular dystrophies. For other issues, it is essential to establish methods to separate ES/iPSC-derived pure skeletal muscle precursor cells from other cell types for safe stem cell therapy that excludes tumorigenic risks of contamination with undifferentiated cells. In the near future, these obstacles will be taken away for more efficient and safe stem cell therapy for DMD and other muscular dystrophies.

The authors declare that they have no conflicts of interest.

This work was supported by the NIH R01 (1R01AR062142) and NIH R21 (1R21AR070319). The authors thank Conor Burke-Smith and Neeladri Chowdhury for critical reading.

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Skeletal Muscle Cell Induction from Pluripotent Stem Cells

CAMBRIDGE, Mass., Nov. 12, 2022 (GLOBE NEWSWIRE) -- Intellia Therapeutics, Inc. (NASDAQ:NTLA), a leading clinical-stage genome editing company focused on developing potentially curative therapeutics leveraging CRISPR-based technologies, today announced updated data from an ongoing Phase 1/2 clinical study of NTLA-2002 for the treatment of hereditary angioedema (HAE). The interim analyses were shared today in a Distinguished Industry Abstract oral presentation at the American College of Allergy, Asthma & Immunology (ACAAI) 2022 Annual Scientific Meeting, being held November 10 – 14 in Louisville, Kentucky.

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Intellia Therapeutics Presents New Interim Data from First-in-Human Study of NTLA-2002 for the Treatment of Hereditary Angioedema (HAE) at the...

CAMBRIDGE, Mass., Nov. 05, 2022 (GLOBE NEWSWIRE) -- Intellia Therapeutics, Inc. (NASDAQ:NTLA), a leading clinical-stage genome editing company focused on developing potentially curative therapeutics leveraging CRISPR-based technologies, today presented additional interim results from an ongoing Phase 1 clinical trial of NTLA-2001, an investigational, in vivo CRISPR/Cas9 genome editing therapy in development as a single-dose treatment for transthyretin (ATTR) amyloidosis in collaboration with Regeneron Pharmaceuticals. Results were presented in a Late-Breaking Science oral presentation at the American Heart Association (AHA) Scientific Sessions 2022, held November 5 – 7 in Chicago, Illinois.

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Intellia Presents Updated Interim Data from the Cardiomyopathy Arm of Ongoing Phase 1 Study of NTLA-2001, an Investigational CRISPR Therapy for the...

Fanconi anemia is a rare genetic disease in which essential DNA repair pathway genes are mutated, disrupting the DNA damage response. Patients with Fanconi anemia experience hematological complications, including bone marrow failure, and are predisposed to cancer. The only curative therapy for the hematological symptoms of Fanconi anemia is an allogeneic hematopoietic stem cell transplant, in which a patient receives healthy stem cells from a donor. While this may cure or prevent some of the diseases complications, stem cell transplantation can cause additional difficulties, including graft-versus-host disease (GvHD) and exacerbated cancer risk.1

There is growing interest in applying genome editing technologies like CRISPR-Cas9 to correct Fanconi anemia mutations in patient-derived cells for autologous transplants, in which corrected stem cells are given back to the patient. However, this disease poses a unique challenge: How do you apply a genome editing technique in cells that are particularly sensitive to DNA damage? Fanconi anemia cells cannot resolve the double-strand breaks that conventional CRISPR-Cas9 gene editing creates in the target DNA, which prevents researchers from effectively correcting disease-causing mutations with this method.

In a study published in International Journal of Molecular Science, a research team at the University of Minnesota led by Branden Moriarity and Beau Webber used Cas9-based tools called base editors (BEs) to edit genes in Fanconi anemia patient-derived cells without inducing double-strand DNA damage.2 BEs are fusion proteins made of a Cas9 enzyme that cleaves target DNA (nCas9) and a deaminase that converts cytidine to uridine (cytosine base editor, CBE) or adenosine to inosine (adenosine base editor, ABE). During DNA replication or repair, sites targeted by a BE are rewritten as thymine in the case of CBEs, or guanine with ABEs.

Although base editors do not induce double-strand breaks, they still nick the DNA and trigger a DNA repair response. Because of this, the researchers first examined if CBEs and ABEs would work on non-Fanconi anemia genes in patient-derived cells. There was that mystery, you know, because [Fanconi anemia patient cells are] DNA repair deficient. So we weren't surewe thought maybe it would work, but not as well as a normal cell. But indeed, it works on the same level, basically. So that was pretty exciting, Moriarity explained.

The research team then demonstrated that CBEs and ABEs can correct Fanconi anemia-causing mutations in the FANCA gene in primary patient fibroblast and lymphoblastoid cell lines. Base editing restored FANCA protein expression and improved the ability of the patient-derived cells to grow in the presence of a DNA damaging chemical. Additionally, in culture, fibroblasts with corrected FANCA mutations outgrew cells in which the base editing failed. Finally, the researchers assessed if BEs could correct mutations in different Fanconi anemia genes. Using an algorithm, they predicted that most Fanconi anemia mutations were correctable either by BEs or by another nCas9-fusion technology called prime editing (PE), which is capable of large genetic insertions and deletions.

This work comes on the heels of a preprint from another research group at The Centre for Energy, Environmental and Technological Research and ETH Zurich, who investigated ABEs in patient blood cell lines. This group also effectively targeted Fanconi anemia genes with BE technology, and their investigation went one step further: they corrected mutations in patient-derived hematopoietic stem cells.3This was something that Moriarity and Webber were unable to dobecause the disease is a bone marrow failure syndrome, these cells are scarce. Basically, these patients do not have stem cells, explains Annarita Miccio, a senior researcher and lab director at Institute Imagine of Paris Cit University, who was not involved in either study. These are very challenging experiments, and more than the experiments, the challenge of [treating] Fanconi anemia is exactly thatthe number of cells.

Despite this challenge, the researchers have laid the groundwork for genome editing as a treatment approach in Fanconi anemia, without the need for double-strand DNA breaks. I think the study we did is a good, solid proof of concept, and sets the stage for the next steps, but certainly, it's not the end of the story, said Webber.

References

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A CRISPR Alternative for Correcting Mutations That Sensitize Cells to DNA Damage - The Scientist

The FDA recently approved two gene therapies with hefty price tags, the first for an inherited anemia and the second for a degenerative brain condition. The two new treatments, from bluebirdbio, double the number of gene therapies on the market.

Most biotechnologies evolve over three decades or so, but the idea of gene therapy has been around since the late 1950s, blooming soon after Watson and Crick solved the structure of DNA. When my book The Forever Fix: Gene Therapy and the Boy Who Saved Itwas published a decade ago, it would still be 5 years before the first approval. That treatment, the subject of my book, enabled the blind to see, sometimes in just days.

Why has the pace of gene therapy been so slow? Cost is one barrier. Other concerns are the degree to which a gene therapy actually helps, how long the effect lasts, and what proportion of patients respond.

FDAs gene therapy roster ishere, but a caveat is necessary.

The list lumps gene therapy in with cell therapy, inviting unintentional hype from media folks unfamiliar with the science. Most entries actually refer to using stem cells to treat blood cancers and related conditions. An example: cartilage cells are sampled from a person with abum knee, mass-produced in a dish, and then injected into the knee, where they fuel production of more cartilage.

My favorite example of not-really-gene-therapy on the FDAs list targetsfacial wrinkles, also using patients lab-expanded cells: 18 million fibroblasts injected three times churn out collagen, filling in the offending skin craters.

Buried in the FDAs list are the first twoactualgene therapy approvals.Luxturna(Spark Therapeutics) treats RPE65 mutation-associated retinal dystrophy and has restored vision in many patients since its approval at the end of 2017. The second approved gene therapy, in 2019, isZolgensma, to treat spinal muscular atrophy, from Novartis Gene Therapies.

FDA approvedZynteglo on August 17, aka betibeglogene autotemcel or eli-cel. It treats the blood disorder beta thalassemia, which causes weakness, dizziness, fatigue, and bone problems. People with severe cases need transfusions of red blood cells every two to five weeks, which can lead to dangerous buildup of iron.

Zynteglo is a one-time infusion of stem cells descended from a patients bone marrow in which functional beta globin genes have been introduced aboard lentiviruses disabled HIV. The $2.8 million treatment is approved for adults and children.

Two clinical trials enrolled 91 patients, 36 of whom improved enough to no longer need transfusions. Bluebird estimates that 1,300 to 1,500 people in the U.S. may be candidates for Zynteglo.

The second go-ahead is forSkysona, approved September 16 for early active cerebral adrenoleukodystropy (CALD). The condition destroys the protective myelin sheath around brain neurons.

A stem cell transplant can cure CALD. Skysona is for the 700 or so boys aged 4 to 17 who cant find matched donors. Nearly fifty percent of them die within five years of symptom onset.

But like many gene therapies, Skysona isnt a magic bullet. In the two ongoing clinical trials, the metric for assessing improvement is slowing neurologic decline, tracking major functional disabilities. These include loss of communication skills, vision, and of voluntary movement, which impairs mobility, eating, and urinary retention.

The 2-year study that led to the FDA approval followed boys with mild or no symptoms, diagnosis possible early due to newborn screening in many states. Those who received Skysona had a 72% likelihood of survival over the two years without developing new major functional disabilities, compared to 43% among untreated boys. The trial will follow participants for 15 years. Since many states are nowscreening newborns for ALD, perhaps boys destined to develop symptoms can receive Skysona before that if someone will pick up the $3 million tab per patient.

Gene therapy companies have long justified high costs with the expense of the bench-to-bedside trajectory. So I was surprised to see a new study published inJAMA Network Open, Association of Research and Development Investments With Treatment Costs for New Drugs Approved From 2009 to 2018, finding none. The authors admonish companies to make further data available to support their claims that high drug prices are needed to recover research and development investments, if they are to continue to use this argument to justify high prices.

Becausethe paperuses terms like first-in-class, accelerated approval, breakthrough therapy, orphan, and priority review language Ive often seen attached to descriptions of gene therapy I assumed it would include Luxturna, which costs $850,000 for both eyes. But the new report omits drug names, instead citing a2020 paperfrom the team that did.No Luxturna. Thats probably because the researchers evaluated R&D costs only for products with publicly available data thats 63 drugs, a mere fifth of new approvals. The new report, of course sent out in news release form to the media, provides more a glimpse than a revelation.

So perhaps gene therapy is an exception for which high prices are indeed required to recoup investment. A viral vector to deliver DNA can cost $500,000 or more to produce, let alone engineer and develop.

Companies also use the one-and-done strategy to justify high prices. The homepage of bluebird bios website, for example, proclaims were pursuing curative gene therapies, although the data on Skysona for CALD indicate incremental change.Axios reports on how Medicaid, private insurers, and companies will help address cost concerns.

While bluebird bio bats around the c word cure it also introduces a long-needed granularity to the terminology. The company has replaced gene therapy with the more accurate gene addition therapy. Thats what the four approved gene therapies actually do add working copies of genes, not fixing them in place. Gene therapy is a little like patching a flat tire, not replacing it.

But the next stage of the evolving technology will in fact befixing genes, courtesy of gene and genome editing. This more precise strategy circumvents the problem of a piece of DNA inserting willy-nilly into a chromosome, perhaps disrupting a cancer-causing gene.

Gene editing with CRISPR has now been around for a decade. The components of the toolkit have been refined to minimize so-called off-target effects that can harpoon unintended genes.

A team atSt. Jude Childrens Research Hospitalhas developed what hematologist Yong Cheng terms the Google Maps of editing the genome. We provide a new approach to identify places to safely integrate a gene cassette. We created step-by-step directions to find safe harbor sites in specific tissues. The recipe is published inGenome Biologyand the tool availablehere.

The approach is seemingly simple. Using data from the 1000 Genomes Project, the tool identifies parts of the genome that often bear inserted or deleted DNA sequences among healthy people (and therefore are harmless) and are highly variable. These are the places where unwound DNA loops about itself when replicating just before a cell divides, and could tolerate a healing gene harpoon going astray.

Safe gene therapy requires two things. Number one, maintaining high expression of the new gene. And number two, the integration needs to have minimal effects on the normal human genome, Cheng said.

Gene addition therapy and gene/genome editing are slowly taking their places among other weapons against genetic disease. These include antisense treatments that glom onto mutant genes, small molecule-based drugs, repurposing existing drugs, supplements, and perhaps most important, the therapies that impact life on a daily basis. And so the toolbox expands to tackle the errors in our genes.

Ricki Lewis has a PhD in genetics and is a science writer and author of several human genetics books.She is an adjunct professor for the Alden March Bioethics Institute at Albany Medical College.Follow her at herwebsiteor Twitter@rickilewis

A version of this article originally appeared at PLOS and is reposted here with permission. Find PLOS on Twitter @PLOS

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Gene therapy approvals now at four with treatments for inherited anemia and degenerative brain condition but costs are stratospheric. Why? - Genetic...

CAMBRIDGE, Mass., Sept. 16, 2022 (GLOBE NEWSWIRE) -- Intellia Therapeutics, Inc. (NASDAQ:NTLA), a leading clinical-stage genome editing company focused on developing potentially curative therapeutics leveraging CRISPR-based technologies, today announced positive interim results from an ongoing Phase 1/2 clinical study of NTLA-2002, its second in vivo genome editing candidate. NTLA-2002 is a systemically administered CRISPR candidate being developed for hereditary angioedema (HAE) and is designed to knock out the KLKB1 gene in liver cells, thereby reducing the production of kallikrein protein. Uncontrolled activity of kallikrein is responsible for the overproduction of bradykinin, which leads to the recurring, debilitating and potentially fatal swelling attacks that occur in people living with HAE. The interim data were shared today in an oral presentation at the 2022 Bradykinin Symposium held in Berlin, Germany.

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Intellia Therapeutics Announces Positive Interim Clinical Data for its Second Systemically Delivered Investigational CRISPR Candidate, NTLA-2002 for...

CAMBRIDGE, Mass. and TARRYTOWN, N.Y., Sept. 16, 2022 (GLOBE NEWSWIRE) -- Intellia Therapeutics, Inc. (NASDAQ:NTLA) and Regeneron Pharmaceuticals, Inc. (NASDAQ:REGN) today announced positive interim results from an ongoing Phase 1 clinical trial of NTLA-2001, an investigational, in vivo CRISPR/Cas9 genome editing therapy in development as a single-dose treatment for transthyretin (ATTR) amyloidosis. The interim data include 12 adult patients with ATTR amyloidosis with cardiomyopathy (ATTR-CM) with New York Heart Association (NYHA) Class I – III heart failure. Single doses of 0.7 mg/kg and 1.0 mg/kg of NTLA-2001 were administered via intravenous infusion, and the change from baseline in serum transthyretin (TTR) protein concentration was measured for each patient.

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Intellia and Regeneron Announce Initial Data from the Cardiomyopathy Arm of Ongoing Phase 1 Study of NTLA-2001, an Investigational CRISPR Therapy for...

Creative Biolabs stem cell platform offers expertise in the generation, bioprocess scale-up, and differentiation of iPSCs.

New York, USA August 3, 2022 Induced pluripotent stem cells (also known as iPS cells or iPSCs) are a type of pluripotent stem cell that can be generated directly from somatic cells. iPSC technology has evolved rapidly since its inception in 2006 and has been widely used for disease modeling.

The global iPSC market is expected to grow from $2431.2 million in 2021 to $2640.80 million in 2022 at a compound annual growth rate (CAGR) of 8.6%. Meanwhile, the market is expected to reach $3571.48 million in 2026 at a CAGR of 7.8%, according to the Report Linker.

Creative Biolabs has constructed an advanced platform that offers various iPSC services, including:

iPSC reprogramming service

iPSC culture service

Pluripotency characterization service

iPSC genome editing service

iPSC differentiation service

With years of exploration in the iPSC development, Creative Biolabs is dedicated to providing helpful iPSC culture services, including maintenance of iPSC, 3D culture of iPSC, as well as scale-up of iPSC culture.

Researchers at Creative Biolabs have built two unique systems for iPSCs culture, which are the feeder-dependent culture system and the feeder-free culture system. In order to break the bottleneck for mass production of high-quality iPSCs, Creative Biolabs has built a 3D culture system for iPSC expansion and differentiation based on a thermoreversible hydrogel. The 3D culture system enables a long-term and serial expansion of multiple human iPSC lines via a mild process. With these wonderful advantages, the 3D culture system may be useful at various scales, from basic biological research to clinical trials.

Moreover, the use of bioreactor systems has greatly improved the development of dynamic suspension culture. Bioreactor systems can promote the control of iPSC aggregation, avoid the formation of gradients, and improve the mass transfer, thus leading to higher cell density.

With the advanced iPSC development platform, Creative Biolabs offers high-quality iPSC genome editing services. Nowadays, the application of custom-engineered sequence-specific nucleases enables genetic changes in human cells to be easily accessed with much greater efficiency and precision, such as CRISPR/Cas9 and TALEN. iPSC genome editing services at Creative Biolabs can help achieve the following goals:

Knock out a gene of interest

Knock in a disease-associated point mutation

Tag a gene of interest with required reporters

Reversion to wildtype in disease-derived iPSC line

Explore more top-notch services for stem cell therapy development at https://www.creative-biolabs.com/stem-cell-therapy.

About Creative Biolabs

With professional scientists and years of experience, Creative Biolabs provides high-quality products and services in the field of stem cell therapy development for customers all over the world.

Media ContactCompany Name: Creative BiolabsContact Person: Candy SwiftEmail: Send EmailPhone: 1-631-830-6441Country: United StatesWebsite: https://www.creative-biolabs.com/stem-cell-therapy

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Creative Biolabs Leads the Forefront of iPSC Technology - Digital Journal

TCR-CAR+ iPSC-derived CD8 T Cells Induced Complete and Durable Responses In Vivo in Systemic Leukemia Model

Cell-surface Markers, Gene Transcription Profile, and In Vivo Anti-tumor Activity of TCR-CAR+ iPSC-derived CD8 T Cells Compared Favorably with Healthy-donor Peripheral Blood CAR T Cells

Phase 1 Study Ongoing of First-ever iPSC-derived T-cell Product Candidate FT819 for Off-the-shelf Treatment of Patients with Relapsed / Refractory B-cell Malignancies

SAN DIEGO, Aug. 09, 2022 (GLOBE NEWSWIRE) -- Fate Therapeutics, Inc. ( FATE), a clinical-stage biopharmaceutical company dedicated to the development of programmed cellular immunotherapies for patients with cancer, today announced the publication of preclinical study results demonstrating the successful generation, durable anti-tumor response, and functional persistence of TCR-CAR+ iPSC-derived CD8 T cells from induced pluripotent stem cells (iPSCs). The CD8 T cells were derived from a single engineered iPSC integrating a novel chimeric antigen receptor (CAR) transgene into the T-cell receptor alpha constant (TRAC) locus, ensuring complete bi-allelic disruption of T-cell receptor (TCR) expression and promoting uniform CAR expression. The discoveries were made under a multi-year research collaboration between the Company and Memorial Sloan Kettering Cancer Center (MSK) led by Michel Sadelain, M.D., Ph.D., Director, Center for Cell Engineering and Head, Gene Expression and Gene Transfer Laboratory, and were published this week in Nature Biomedical Engineering.

Scientists have previously differentiated induced pluripotent stem cells to form CAR T cells, however, it was observed that premature TCR or constitutive CAR expression resulted in the derivation of innate-like T cells that do not acquire the phenotype nor exhibit the function of conventional CD8 T cells, said Dr. Sadelain. Our published findings are the first to show the generation of iPSC-derived CD8 CAR T cells lacking a TCR, where timed and calibrated expression of the CAR in place of the TCR successfully drove T-cell maturation and promoted the acquisition of a transcriptional and functional profile more closely resembling that of natural CD8 T cells.

The mass production of TCR-CAR+ CD8 T cells from master engineered iPSC lines is a promising approach for development of off-the-shelf, cell-based cancer immunotherapies. Through a systematic assessment of factors that affect T-cell lineage commitment and induce adaptive T-cell formation, the researchers discovered that integrating the CAR construct into the TRAC locus delayed its expression and drove T-cell lineage commitment, and that regulation of CAR signaling strength promoted the generation of CD4+CD8+ double-positive cells mimicking thymic development in the absence of a TCR. Subsequent stimulation of the CAR matured the double-positive population into single-positive CD8 T cells with a phenotype highly correlated with peripheral blood CD8 effector T cells and distinct from T cells and natural killer cells. Preclinical studies showed that iPSC-derived TCR-CAR+ CD8 T cells were able to repeatedly lyse tumor cells in vitro and durably control leukemia in vivo, with persistence in the bone marrow, spleen, and blood, in a systemic NALM6 leukemia model.

These published findings continue to support our unique ability to generate TCR-CAR+ CD8 T cells from master engineered iPSC lines that exhibit a phenotypic profile and anti-tumor activity comparable to healthy donor-derived peripheral blood CAR T cells in preclinical model systems, said Scott Wolchko, President and Chief Executive Officer of Fate Therapeutics. We believe our off-the-shelf, iPSC-derived CAR T cell programs overcome the numerous challenges associated with the manufacture, consistency, and reach of autologous and allogeneic CAR T cells, and we look forward to sharing initial clinical data from our landmark Phase 1 study of FT819 later this year.

The Company is conducting a multicenter Phase 1 study of FT819, the first T-cell therapy manufactured from a clonal master iPSC line to undergo clinical investigation. The product candidates clonal engineered master iPSC line is created from a single iPSC that has a novel CD19-targeted 1XX CAR construct integrated into the TRAC locus, ensuring complete bi-allelic disruption of TCR expression to prevent graft-versus-host disease and promoting uniform CAR expression for enhanced anti-tumor activity. Dose escalation is currently ongoing in single-dose and multi-dose escalation cohorts for relapsed / refractory B-cell malignancies.

Pursuant to a license agreement with MSK, Fate Therapeutics has an exclusive license for all human therapeutic use to U.S. Patent No. 10,370,452, which covers compositions and uses of effector T cells expressing a CAR, where such T cells are derived from a pluripotent stem cell including an iPSC. In addition to the patent rights licensed from MSK, the Company owns an extensive intellectual property portfolio that broadly covers compositions and methods for the genome editing of iPSCs using CRISPR and other nucleases, including the use of CRISPR to insert a CAR in the TRAC locus for endogenous transcriptional control.

Fate Therapeutics has licensed intellectual property from MSK on which Dr. Sadelain is an inventor. As a result of the licensing arrangement, MSK has financial interests related to Fate Therapeutics.

About Fate Therapeutics iPSC Product PlatformThe Companys proprietary induced pluripotent stem cell (iPSC) product platform enables mass production of off-the-shelf, engineered, homogeneous cell products that are designed to be administered with multiple doses to deliver more effective pharmacologic activity, including in combination with other cancer treatments. Human iPSCs possess the unique dual properties of unlimited self-renewal and differentiation potential into all cell types of the body. The Companys first-of-kind approach involves engineering human iPSCs in a one-time genetic modification event and selecting a single engineered iPSC for maintenance as a clonal master iPSC line. Analogous to master cell lines used to manufacture biopharmaceutical drug products such as monoclonal antibodies, clonal master iPSC lines are a renewable source for manufacturing cell therapy products which are well-defined and uniform in composition, can be mass produced at significant scale in a cost-effective manner, and can be delivered off-the-shelf for patient treatment. As a result, the Companys platform is uniquely designed to overcome numerous limitations associated with the production of cell therapies using patient- or donor-sourced cells, which is logistically complex and expensive and is subject to batch-to-batch and cell-to-cell variability that can affect clinical safety and efficacy. Fate Therapeutics iPSC product platform is supported by an intellectual property portfolio of over 350 issued patents and 150 pending patent applications.

About FT819FT819 is an investigational, universal, off-the-shelf, T-cell receptor (TCR)-less CD19 chimeric antigen receptor (CAR) T-cell cancer immunotherapy derived from a clonal master induced pluripotent stem cell (iPSC) line, which is engineered with the following features designed to improve the safety and efficacy of CAR19 T-cell therapy: a novel 1XX CAR signaling domain, which has been shown to extend T-cell effector function without eliciting exhaustion; integration of the CAR19 transgene directly into the T-cell receptor alpha constant (TRAC) locus, which has been shown to promote uniform CAR19 expression and enhanced T-cell potency; and complete bi-allelic disruption of TCR expression for the prevention of graft-versus-host disease. FT819 demonstrated antigen-specific cytolytic activity in vitro against CD19-expressing leukemia and lymphoma cell lines comparable to that of primary CAR T cells, and persisted and maintained tumor clearance in the bone marrow in an in vivo disseminated xenograft model of lymphoblastic leukemia. FT819 is being investigated in a multicenter Phase 1 clinical trial for the treatment of relapsed / refractory B-cell malignancies, including B-cell lymphoma, chronic lymphocytic leukemia, and acute lymphoblastic leukemia (NCT04629729).

About Fate Therapeutics, Inc.Fate Therapeutics is a clinical-stage biopharmaceutical company dedicated to the development of first-in-class cellular immunotherapies for patients with cancer. The Company has established a leadership position in the clinical development and manufacture of universal, off-the-shelf cell products using its proprietary induced pluripotent stem cell (iPSC) product platform. The Companys immuno-oncology pipeline includes off-the-shelf, iPSC-derived natural killer (NK) cell and T-cell product candidates, which are designed to synergize with well-established cancer therapies, including immune checkpoint inhibitors and monoclonal antibodies, and to target tumor-associated antigens using chimeric antigen receptors (CARs). Fate Therapeutics is headquartered in San Diego, CA. For more information, please visit http://www.fatetherapeutics.com.

Forward-Looking StatementsThis release contains "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995 including statements regarding the advancement of and plans related to the Company's product candidates, clinical studies and preclinical research and development programs, the Companys progress, plans and timelines for the manufacture and clinical investigation of its product candidates, the Companys initiation and continuation of enrollment in its clinical trials including additional dose cohorts in ongoing clinical trials of its product candidates, the therapeutic and market potential of the Companys product candidates, and the Companys clinical development strategy, including for its product candidate FT819. These and any other forward-looking statements in this release are based on management's current expectations of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in or implied by such forward-looking statements. These risks and uncertainties include, but are not limited to, the risk that the Companys product candidates may not demonstrate the requisite safety or efficacy to warrant further development or to achieve regulatory approval, the risk that results observed in prior studies of the Companys product candidates, including preclinical studies and clinical trials, will not be observed in ongoing or future studies involving these product candidates, the risk of a delay or difficulties in the manufacturing of the Companys product candidates or in the initiation and conduct of, or enrollment of patients in, any clinical trials, the risk that the Company may cease or delay preclinical or clinical development of any of its product candidates for a variety of reasons (including requirements that may be imposed by regulatory authorities on the initiation or conduct of clinical trials, changes in the therapeutic, regulatory, or competitive landscape for which the Companys product candidates are being developed, the amount and type of data to be generated or otherwise to support regulatory approval, difficulties or delays in patient enrollment and continuation in the Companys ongoing and planned clinical trials, difficulties in manufacturing or supplying the Companys product candidates for clinical testing, and any adverse events or other negative results that may be observed during preclinical or clinical development), the risk that results observed in preclinical studies of FT819 may not be replicated in ongoing or future clinical trials, and the risk that FT819 may not produce therapeutic benefits or may cause other unanticipated adverse effects. For a discussion of other risks and uncertainties, and other important factors, any of which could cause the Companys actual results to differ from those contained in the forward-looking statements, see the risks and uncertainties detailed in the Companys periodic filings with the Securities and Exchange Commission, including but not limited to the Companys most recently filed periodic report, and from time to time in the Companys press releases and other investor communications. Fate Therapeutics is providing the information in this release as of this date and does not undertake any obligation to update any forward-looking statements contained in this release as a result of new information, future events or otherwise.

Contact:Christina TartagliaStern Investor Relations, Inc.212.362.1200[emailprotected]

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Fate Therapeutics Announces Preclinical Publication Highlighting Derivation of CD8 T Cells from TCR-CAR+ Induced Pluripotent Stem Cells -...

Introduction

Stem cells are highly specialized cell types with an impressive ability to self-renew, able to transform into one or even more specific cell types that play a significant role in the regulation and tissue healing process.17 To self-renew, a stem divides into two identical daughter stem cells and a progenitor cell and the embryonic and adult cells contain stem cells.1,2,8

Curing patients with serious medical conditions has been the focus of all disciplines of medical research for many years. Stem cell treatment has evolved into a highly exciting and progressed field of scientific research. Major advances have recently been introduced in fundamental and translational stem-cell-based treatment studies. As stem cell research progressed, many therapeutic options were investigated. The development of therapeutic procedures has sparked a great deal of interest.1,9 Humanity has known for many years that it is possible to regenerate lost tissue. Recently, the regenerative medicine research has taken hold, defying the tremendous scientific advances in the molecular biology sciences only. Technological advances provide limitless opportunities for transformational and potentially restorative therapies for many of humanitys most illnesses. A variety of human organs have successfully yielded stem cells. Besides this, the cell therapy is rapidly bringing good advancements in the healthcare system, intending to restore and possibly replace injured tissue, as well as organs, and ultimately restore the functional capacity of the body.2,10,11

The stem cells can be obtained from various sources of Adult (Adult body tissues), Embryonic (Embryos), Mesenchyma (Connective tissue or stroma), and Induced pluripotent stem [ips] cells (Skin cells or tissue-specific cells).3,68,1215

Due to various stem cells cellular characteristics, the therapeutic clinical possibilities of stem-cell-based treatment are considered promising. These cells can regrow and restore various types of body tissues, for this reason, they are recognized as precursor cells to all kinds of cells.15 The following are the distinguishing features: 1. Self-renewal- Divide without distinction to generate an infinite supply, 2. Multi-potency- One mature cell may distinguish more than one, 3. Pluripotency- Create all sorts of cells except for embryonic membrane cells, 4. Toti- potency- Produce various sorts of cells, including embryonic stem cells.1,2,6,7,16

Stem cells are essential human cells that really can self-renew and make a distinction into particular mature cell types.3,6 The different types of stem cells are embryonic, induced pluripotent, and adult kind of cell types. They all share the important feature of self-renewal, and the ability to discern themselves. It should be mentioned that, the stem cells are not homogeneous, but instead appear in a progressive order. Totipotent stem cells are the most basic and immature stem cells. The above cells can form a complete embryo and also extra-embryonic tissue. This one-of-a-kind efficiency is only present for a short period, starting with ovum development and completing whenever the embryo achieves the 4 to 8 cell phases. Having followed that, cells that divide until they approach the blastocyst, about which point they end up losing their totipotency and acquire a pluripotent character trait, at which cells can only distinguish through each embryonic germ stack. After a few divisions, the pluripotency character trait starts to fade and the distinguishing ability has become more lineage constrained, where its cells are becoming multipotent, indicating they could only transform into the cells connected to a cell or tissue of origin.10 Many researchers believe that adult stem cells should be used in stem cell therapies.6,17

The stem cells can be transformed into a wide range of specialized functional cell types.3,18 In response to injury or maturation, those same stem cells can propagate in massive quantities.19 Adult, embryonic, and induced pluripotent stem cells are examples of stem cell-based therapies.14,15,1921 The stem cells, due to their capability to distinguish the specific cell types requisite for a diseased tissue regeneration, can provide an effective solution, while tissue and organ transplantation are considered necessary.10 The sophistication of stem cell-based treatment interventions, on the other hand, probably leads researchers to seek stable, credible, and readily available stem cell sources capable of converting into numerous lineages. As an outcome, it is critical to exercise caution when selecting the type of stem cells to be used in therapeutic trials.12,14,22

Only with the explosive growth of basic stem cell research in recent years, the comparatively recent study sector of Translational Research had also grown exponentially, starting to build on major research knowledge and insight to advance new therapies. Once the necessary regulatory clearances have been obtained, the clinical translation process can start. Translational research is important because it acts as a filtration system, ensuring that only safe and effective therapeutic approaches start making it to the clinic.23 Recent research illustrating, the successful application of stem cell transplantation to patient populations suggests that, such restorative approaches have been used to address a wide variety of complicated ailments of future concerns.19,24

Currently, clinical trials are available for a variety of stem cell-based treatments based on adult stem cells. To date, the WHO International Clinical Experiments Registration process has recorded more than 3000 experiments involved based on adult stem cells. Furthermore, preliminary trials involving novel and intriguing pluripotent stem cell therapies have been registered. These studies findings will assist the ability to comprehend and the timeframes required to obtain effective treatments and it will contribute to a better knowledge of the different disorders or abnormalities.10

The role of stem cells in modern medicine is vital, both for their widespread application in basic research and for the opportunities they provide for developing new therapeutic strategies in clinical practice.6,16 In recent times, the number of studies involving stem cells has expanded tremendously. Globally, thousands of studies claiming to use stem cells in experimental therapies have now been in the investigation field. This may give the impression that such treatments have already been shown to be extremely effective in the context of healthcare. Despite some promising results, the vast majority of stem cell-based therapeutic applications are still in the experimental stage itself.6,25

The stem cells are a valuable resource for understanding organogenesis as well as the bodys continual regenerative capacity. These cells have brought up enormous anticipations among doctors, investigators, patients, and the public at large because of their ability to distinguish into a variety of cell types.25 These cells are necessary for living beings for a variety of reasons and can play a distinguishable role. Several stem cells can play all cell types roles, and when stimulated effectively, they can also repair damaged tissue. This capability has the potential to save lives as well as treat human injuries and tissue destruction. Moreover, different kinds of stem cells could be used for several purposes, including tissue formation, cell deficiency therapeutic interventions, and stem cell donation or retrieval.3,6,26

New research demonstrating that the successful application of stem cell treatments to patients has expressed hope that such regenerative strategies might very well one day is being used to address a wide variety of problematic ailments. Furthermore, clinical trials incorporating stem cell-based therapeutics have advanced at an alarming rate in recent years. Some of these studies had a significant impact on a wide range of medical conditions.10 As a regenerative medicine strategy, cell-based treatment is widely regarded as the most fascinating field of study in advanced science and medicine. Such technological innovation paves the way for an infinite number of transformational and potentially curable solutions to some of humanitys most pressing survival issues. Moreover, it is gradually becoming the next major concern in medical services.11

Modern data, which shows that the successful stem cell transplantation in beneficiaries has raised hopes on the certain rejuvenating approaches, will one day be used to treat many different types of challenging chronic conditions.24 Preliminary data from highly innovative investigations have documented that the prospective advancement of stem cells provides a wide range of life-threatening ailments that have so far eluded current medical therapy.2,10,11 Furthermore, clinical trials involving stem cell-based therapies have advanced at an unprecedented rate. Many of these studies had a significant impact on various disorders.19 Despite the increasing significance of articles concerning viable stem cell-based treatments, the vast majority of clinical experiments have still yet to receive full authorization for stem cell treatments confirmation.11,12,27

Even though the first case of AIDS were noted nearly 27 years ago, and the etiologic agent was noticed 25 years ago, still for the effective control of the AIDS pandemic continues to remain elusive.28 The HIV epidemic started in 1981 when a new virus syndrome defined by a weakened immune system was revealed in human populations across the globe. AIDS showed up to have a substantial reduction in CD4+ cell counts and also elevated B-cell multiplication.15,2831

The agent that causes AIDS, later named HIV, is a retroviral disease with a genomic structural system made up of 2 identical single-stranded RNA particles.3234 According to the Centres for Disease Control and Prevention, with over 1.1 million Americans are presently infected with the virus.31 Compromised immune processes in HIV and AIDS, as well as partial immune restoration, barriers are confirmed for HIV disease eradication. Innovative developmental strategies are essential to maximizing virus protection and enabling the host immune response to eliminate the virus.35

The progression of HIV infection in humans is divided into the following stages of acute infection, chronic infection, and AIDS.15,36 During the acute infection phase, the circulation has a high viral replication, is extremely infectious, that may or may not demonstrate flu-like clinical signs. In the chronic stage, the viral load is lesser than in the acute stage, and individuals are still infectious but may be symptomless. The patient has come to the end stage of AIDS whenever the CD4+ cell count begins to fall below 200 cells/mm or even when opportunistic infections are advanced.15,36

There are currently two types of HIV isolated HIV-1 and HIV-2.15,37,38 However, HIV-1 is the most common cause of AIDS throughout the world, while HIV-2 is only found in a few areas of an African country. Although both virions can cause AIDS, HIV-2 infection is much more likely to occur in central nervous system disorder.15 Besides this, HIV-2 seems to be less infectious than HIV-1, and HIV-2 infection induces AIDS to develop more slowly. Even though both HIV-1 and HIV-2 have a comparable genetic structure comprised of group-specific antigen, polymerase, and envelope genes, their genome organizational structures are differed.15,3739

HIV infiltrates immune cell types, CD4+ T cell types, and monocytes, resulting in a drop in T-cell counts below a critical level and the failure of cell-mediated immune function.15,40 The glycoprotein (gp120) observed in the virion envelope comes into contact with the CD4 particle with high affinity, allowing HIV to infect T cells. By interacting with their co-receptors, CXCR4 and CCR5, the virus infiltrates T cells and monocytes. The retrovirus uses reverse transcriptase to convert its RNA into DNA after attaching it to and entering the host cell. These newly replicated DNA copies then exit the host cell and infect other cells.15,40,41

HIV-1 is a retrovirus and belongs to a subset of retroviruses known as lentiviruses.38,42 Infection is the most common global health concern around the world.15 It has destroyed the millions of peoples health and continues to wreak havoc on the individual health of millions more. The pandemic of HIV-1 is the most devastating plague in the history of humans, as well as a significant challenge in the areas of medicine, public health, and biological science of research activities.34,43 Antiretroviral therapy is the only treatment that is commonly used. This is not a curative treatment; it must be used for the rest of ones life.15 Although antiretroviral therapy has reduced significantly HIV intensity and transmission, the virus has not been eradicated, and its continued presence can lead to additional health issues.44

Infection with the human immunodeficiency virus necessitates entry into target cells, such as through adhesion of the viral envelope to CD4 receptor sites.43 Cellular antiviral responses fail to eliminate the virus, resulting in a gradual depletion of CD4+ T cells and, finally, a severely compromised immune functioning system. Unfortunately, there is no cure for the virus that destroys immunity.4447 In advanced HIV infection, memory T-cell depletion primarily affects cellular and adaptive immune responses, with a minor impact on innate immune responses.48 Globally, 37.7 million people were living with HIV in 2020, and with 1.5 million individuals are infected with the virus.49 The advancement of stem cell therapy and the conduct of implemented clinical trials have revealed that stem cell treatment has high hopes for a range of medical conditions and implementations.15

Stem cell treatment has shown impressive outcomes in HIV management and has the potential to have significant implications for HIV treatment and prevention in the future. In HIV patients, stem cell therapy helps to suppress the viral load even while enabling antiretroviral regimens to be tapered. Interestingly, this practice led to a significant improvement in procedure outcomes soon after starting antiretroviral treatment.15 Stem cell transplantation can alleviate a wide variety of diseases that are currently incurable. They could also be used to create a novel anti-infection therapy strategic plan and to enhance the treatment of immunologic conditions such as HIV infection. HIV wreaks havoc on immune system cells.30,50

The virus infects and replicates within T-helper cells (T-cells), which are white immune system cells. T-cells are also referred to as CD4 cells. HIV weakens a persons immune system over time by pulverizing more CD4 cells and multiplying itself. More pertinently, if the individual has been unable to obtain anti-retroviral medicine, he will progressively fail to control the infectious disease and illnesses.3,15,42

Despite 36 years of scientific research, investigators are still trying to cure human HIV and its potential problem, AIDS.3,5153 HIV continues to face unconquerable dangers to human survival. This virus has developed the potential to avoid anti-retroviral therapy and tends to result in victim death.52 Investigators are still looking for effective and all-encompassing treatment for HIV and its complexity, AIDS.54 This massive amount of data revealed potential AIDS treatment targets.55 Thousands of research projects have yielded a great deal of information on the elusive AIDS life cycle to date.5456 These massive amounts of data supplied possible targets for AIDS treatment.33,55,56 In HIV-infected patients, using stem cell therapy can augment the process of keeping the viral load stagnant by permitting antiretroviral regimens to be tapered.15

Overall, stem cell-based strategies for HIV and AIDS treatment have recently emerged and have become a key area of research. Ideally, effective stem cell-based therapeutic approaches might have several benefits.30 Clinical studies encompassing stem cell therapy have shown substantial therapeutic effects in the treatment of various autoimmune, degenerative, and genetic problems.15,25 Substantial progress has been developed in the treatment of HIV infection using stem cell-based techniques.30

Successfully treated, clinical studies have shown that total tissue recovery is feasible.15,57 In the early 1980s, the first stem cell transplants were accomplished on HIV-positive patients who were unsure of their viral disease. Following the above preliminary aspects, many HIV-positive patients with concurrent malignant tumours or other hematologic disorders underwent allogeneic stem cell transplantation around the world.42 After ART became a common treatment option for patients,58,59 the procedures prognosis improved dramatically. In addition, a retrospective study of 111 HIV+ transplant patients demonstrated a mildly lower overall survivorship performance in comparison to an HIV-uninfected comparison group.60

Earlier, the primary problem for people living with HIV and AIDS was immunodeficiency caused by a loss of productive T-cells. Some clinicians intended to replenish lost lymphocytes through adoptive cell transplants in the initial days before efficacious antiretroviral therapy options were available. Immunologically, it is relatively simple in an isogeneic condition, as illustrated on HIV-positive individuals with just a correlating identical twin who received T-lymphocytes and stem cell transfusions to rebuild the weak immune status of the patient.60 Cell therapy transfusion may be used to remove resting virion genomes from CD4+ immune cells and macrophages mostly through genome-editing or cytotoxic anti-viral cells.15,60 Cell technology and stem cell biological reprogramming developments have made a significant contribution to novel strategies that may give confidence to HIV healing process.3 However, human embryonic stem cells can be distinguished into significant HIV target cells, according to several research findings.30,61,62

Initially, stem cell transplantation was believed to influence the clinical significance of HIV infection, but viral regulation was not accomplished in the discipline. Moreover, improvements in stem cell transplants utilizing synthetic or natural resistant cell resources, in combination with novel genetic manipulative tactics or the advancement of cytotoxic anti-HIV effector cells, have significantly accelerated this sector of HIV cell management.60 Multiple techniques are being introduced to overcome HIV, either through protecting cells from infectious disease or by continuing to increase immune responses to the viral infection.30 The various methods are as follows: Bone marrow stem cells Therapies, Autologous stem cell transplantations, Hematopoietic stem cell transplantation, Genetical modifications of Hematopoietic stem cells (HSCT), HSCT and HAART therapeutic approach, Human umbilical cord mesenchymal stem cell transplantation, Mesenchymal stem/stromal cells (MSCs) applications, CCR5 Delta32/Delta32 Stem-Cell Transplantation, CRISPR and stem cell applications, Induced Pluripotent Stem Cells applications.

According to the findings, circulating replicative HIV remains the most significant threat to effective AIDS therapy. As a result, a method for conferring resistance to circulating HIV particles is required. The effective viral burden in the human body would be significantly reduced if it were possible to defeat reproducing HIV particles.43,44 For the treatment of AIDS, a restorative approach that relies on bone marrow stem cells has been suggested.52 The proposed treatment method captures and eventually destroys circulating HIVs using receptor-integrated red blood cells. Red blood cell membranes can be equipped with the CD4 receptor and the C-C chemokine receptor type 5 and C-X-C chemokine receptor type 4 co-receptors, which will selectively bind circulating HIV particles.15,30,32,33,43,44,46,6365

The term autologous pertains to blood-forming stem cells obtained from the patient for use as a source of fresh blood cells followed by high-dose chemotherapeutic agents.66 Lymphoma is still the biggest cause of mortality in HIV patients. Autologous stem cell recovery or transplantation with high-dose treatments has long been supported as a treatment for certain types of cancer in HIV-negative patients, including leukaemia and lymphoma. Individuals over the age of 65, as well as those with health problems such as HIV, were excluded from initial transfusion experiments. Moreover, the treatment regimen mortality of transplantation has also been reduced significantly due to its use of peripheral blood stem cells rather than bone marrow and the use of newer marginal conditioning therapeutic strategies. HIV-infected clients may be able to utilize enough stem cells for an autologous transplant advancement in HIV management. High-dose Autologous stem cell transplant (ASCT) treatments are better than conventional treatment in people with relapsed non-Hodgkin lymphoma, according to randomized trial evidence. Similarly, studies on HIV-negative people with Hodgkin Lymphoma have shown that ASCT would provide patients with repetitive illness with long-term progression-free survival.66,67 Even so, the clinical trial on Allogeneic Hematopoietic Cell Transplant for HIV Patients with Hematologic Malignancies report was explained as, the cell-associated HIV DNA and inducible infectious virus were not detectable in the blood of patients who attained complete chimerism.68

The study on long-term multilineage engraftment of autologous genome-edited hematopoietic stem cells in nonhuman primates report findings was Genome editing in hematopoietic stem and progenitor cells (HSPCs) is a potential innovative approach for the treatment of numerous human disorders. This report shows that genome-edited HSPCs engraft and contribute to multilineage repopulation following autologous transplantation in a clinically relevant large animal model, which is an important step toward developing stem cell-based genome-editing therapeutics for HIV and possibly other illnesses.69

Research on comprehensive virologic and immune interpretation in an HIV-infected participant again just after allogeneic transfusion and analytical interruption of antiretroviral treatment findings are the instance of HIV-1 cure having followed allogeneic stem cell transplantation (allo-SCT), resulting allo-SCTs in HIV-1 positive participants have failed to cure the disease. It describes adjustments in the HIV reservoir in a single chronically HIV-infected client who had undergone allo-SCT for acute lymphoblastic leukaemia treatment and was obtaining suppressive antiretroviral treatment.

To estimate the size of the HIV-1 reservoir and describe viral phylogenetic and phenotypic modifications in immune cells, the investigators just used leukapheresis to obtain peripheral blood mononuclear cells (PBMCs) from a 55-year-old man with chronic HIV infection prior and after allo-SCT. Once HIV-1 was found to be unrecognizable by numerous tests, including the PCR measurement techniques both of overall and fully integrated HIV-1 DNA, recompilation virus precise measurement by significant cell input quantifiable viral outgrowth assay, and in situ hybridization of intestine tissue, the client accepted to an analytic treatment interruption (ATI) with recurrent clinical observing on day 784 post-transplantation. He continued to remain aviremic off ART until ATI day 288, once a reduced virus rebound of 60 HIV-1 copies/mL resulted, which expanded to 1640 HIV-1 copies/mL five days later, urging ART reinitiation. Rebounding serum HIV-1 action sequences were phylogenetically distinguishable from pro-viral HIV-1 DNA discovered in circulating PBMCs before transplantation. It was indicated that allo-SCT tends to result in significant reductions in the magnitude of the HIV-1 reservoir and a >9-month ART-free cessation from HIV-1 multiplication.34

The Impact of HIV Infection on Transplant Outcomes after Autologous Peripheral Blood Stem Cell Transplantation: A Retrospective Study of Japanese Registry Data reported as ASCT is a successful treatment option for HIV-positive patients with non-Hodgkin lymphoma and multiple myeloma (MM). HIV infection was associated with an increased risk of overall mortality and relapse after ASCT for NHL in a study population.70

The procedure of delivering hematopoietic stem cells mostly through intravenous infusion to restore normal haematopoiesis or treat cancer is known as hematopoietic stem cell transplantation.71 There has recently been a rise in the desire to develop strategies for treating HIV/AIDS diseases employing human hematopoietic stem cells,30 along with this Hutter and Zaia were evaluated the background of Haematopoietic stem cell transplantation (HSCT) in HIV-infected individuals.42

Attempts to use HSCT as a technique for immunologic restoration in AIDS patients or as a therapeutic intervention for malignant tumours were initially insufficient. Regretfully, in the absence of sufficient ART, HSCT seemed to have no impact on the evolution of HIV infection, and the majority of the patients ended up dead of rapidly deteriorating immunosuppression or reoccurring lymphoma or leukaemia. A specific instance report described how an un-associated, matched donor supplied allogeneic HSCT to a patient with refractory lymphoma. The virus was unrecognizable by isolating or PCR of peripheral blood mononuclear cells commencing on day 32 after transplantation. Although HIV-1 was unrecognizable by cultural environment or PCR of several tissues examined at mortem, the patient died of recurring lymphoma on day 47. Another client who obtained both allogeneic HSCT and zidovudine had similar results, with HIV-1 becoming unnoticeable in the blood by PCR analysis. In some other particular instances, a 25-year-old woman with AIDS who obtained an allogeneic HSCT from a corresponding, unfamiliar donor after controlling with busulfan and cyclophosphamide and ART with zidovudine and IFN-2 regimen continued to live for 10 months before falling victim to adult respiratory distress. However, PCR testing of autopsy tissues revealed that they were HIV-1 negative.72

Recent research discovered significant progress towards the clinical application of stem cell-based HIV therapeutic interventions, principally illustrating the opportunity to effectively undertake a large-scale phase two HSC-based gene therapy experiment. In this investigation, the research team used autologous adult HSCs that had been transduced to a retroviral vector that usually contains a tat-vpr-specific anti-HIV ribozyme to develop cells that were less vulnerable to productive infection,73 whereas vector-containing cells have been discovered for extended periods (more than 100 weeks in most people) and CD4+ T cell gets counted were significantly high within anti-HIV ribozyme treating people group compared with the placebo group, the impacts on viral loads were minimal. The studys success, even so, is based on the realization that a stem cell-based strategy like this is being used as a more conventional and efficacious therapeutic approach.30 Some other latest clinical studies used a multi-pronged RNA-based strategic plan which included a CCR5-targeted ribozyme, an shRNA targeting tat/rev transcripts, and a TAR segment decoy.74

These crucial research findings are explained on lentiviral-based gene therapy vectors that can genetically manipulate both dividing and non-dividing HSCs and are less likely to cause cellular changes than murine retro-viral-based vectors. Long-term engraftment and multipotential haematopoiesis have been demonstrated in vector-containing and expressing cells, according to the researchers. Whereas the antiviral effectiveness was not reviewed, the results demonstrate the strategys protection, which helps to expand well for the possibility of a lentiviral-based approach in the upcoming years.30

A further approach, with a different emphasis, has been started up in the hopes of trying to direct immune function to target specific HIV to overcome barriers to attempting to clear the virus from the patient's body. These strategies use gene treatment innovations on peripheral blood cells to biologically modify cells so that they assert a receptor or chimeric particle that enables them to especially target a specific viral antigen,75 deception of HIV-infected peoples peripheral blood T cells raises issues to be addressed, such as the effects of ongoing HIV infection and ex vivo modification on the capabilities and lifetime of peripheral blood cells. Further to that, the above genetically manipulated cells would demonstrate their endogenous T cell receptors, and the representation of the newly introduced receptor could outcome in cross-receptor pairing, resulting in self-reactive T cells. Most of these deficiencies could be countered by enabling specific developmental strategies to take place that can start generating huge numbers of HIV-specific cells in a renewable, consistent way that can restore defective natural immune activity against HIV.30

One strategy being recognized is the application of B cells obtained from HSCs to demonstrate anti-HIV neutralizing specific antibodies. While animal studies have shown that neutralizing antibodies could protect against infection, and extensively neutralizing antibodies have been noticed in some HIV-infected persons, safety from a single engineered antibody might be exceptional.76,77 Realizing antibody binding and virus neutralization may assist in the development of chimeric receptors or single-chain therapeutic antibodies with recognition domains for other techniques that identify cellular immunity against HIV-infected cells.78,79 Thereby, genetically modifying HSCs to generate B cells that produce neutralizing anti-HIV specific antibodies, or engineering HSCs to enable multipotential haematopoiesis of cells that express a chimeric cellular receptor usually contains an antibody recognition domain, indicate one arm of an HSC-based engineered immunity process.30

A further technique of using HSCs that were genetically altered with molecularly cloned T-cell receptors or chimeric molecules particular to HIV to yield antigen-specific T cells. The basic difference in this strategy is that the cells produced from HSCs after standard advancement in the bone marrow and thymus are made subject to normal central tolerance modalities and are antigen-specific naive cells, and therefore do not have the ex-vivo manipulation and impaired functioning or exhaustion problems that other external cell modification methods would have. In this context, the latest actual evidence research using a molecularly cloned T cell receptor particular to an HIV-1 Gag epitope in the aspect of HLA-A*0201 revealed that HSC altered in this ability can progress into fully functioning, mature HIV specialized CD8+ T cells in human thymic tissue that conveys the acceptable constrained HLA-A*0201 particles.80 This explores the possibility of genetically engineering HSCs with a molecularly cloned receptor and signifies a step toward a better understanding and application of initiated T cell responses, which would probably result in the eradication of HIV infection from the body, similar to the natural immune function of other virus infections and pathogenic organisms.30

In an allogeneic transplantation, donor stem cells replace the patients cells.66 Allogeneic hematopoietic stem cell transplantation (HSCT) has appeared as one of the most potent treatment possibilities for many people who suffer from hemopoietic system carcinomas and non-malignant ailments.81 Both HIV-cured people have received HSCT utilizing CCR5 132 donor cells.82,83 This implies that HIV eradication necessitates a decrease in the viral reservoir through the myeloablative procedures,8486 Having followed that, immune rebuilding with HIV-resistant cells was carried out to prevent re-infection.45 The possibility of adoptive transfer of ex vivo-grown, virus-specific T-cells to prevent and control infectious diseases (eg, Cytomegalovirus and EBV) in immunocompromised patients helps to make adoptive T-cell treatment a feasible strategy to inhibit HIV rebound having followed HSCT.81,87,88

The Engineered Zinc Finger Protein Targeting 2LTR Inhibits HIV Integration in Hematopoietic Stem and Progenitor Cell-Derived Macrophages: In Vitro Study, the researchers investigated the efficacy and safety of 2LTRZFP in human CD34+ HSPCs. Researchers used a lentiviral vector to transduce 2LTRZFP with the mCherry tag (2LTRZFPmCherry) into human CD34+ HSPCs. The study findings suggest that the anti-HIV-1 integrase scaffold is an enticing antiviral molecule that could be utilised in human CD34+ HSPC-based gene therapy for AIDS patients.89

The fundamental element of HIV management is stem cell genetic modification, which involves genetically enhanced patient-derived stem cells to overcome HIV infection. In this sector, numerous experimental studies, in vitro as well as in vivo examinations, and positive outcomes for AIDS patients have been conducted.65,74 Genetic engineering for HIV-infected individuals can provide a once-only intervention that minimizes viral load, restores the immune system, and minimizes the accumulated toxicities concerned with highly active antiretroviral therapy (HAART).73 HSCs can be genetically altered, permitting for the addition of exogenous components to the progeny that protects them from direct infectious disease and/or enables them to target a specific antigen. Besides that, HSC-based strategies can enhance multilineage hemopoietic advancement by re-establishing several arms of the immune function. Eventually, as HSCs can be produced autologously, immunologic tolerance is typically high, enabling effective engraftment and subsequent distinction into the fully functioning mature hematopoietic cells.30

The utilization of human HSCs to rebuild the immune function in HIV disease is one application that tries to preserve newly formed cells from HIV infection, while another attempts to develop immune cells that attack HIV infected cells. While each initiative has many different aspects at the moment, they represent huge attention to HIV/AIDS therapies that, most likely when integrated with the other therapeutic approaches, would result in the body trying to overcome the obstacles needed for the virus to be effectively cleaned up.30

While HSC transplantation technique and processes are not accurately novel, as they are commonly and effectively used to address a wide variety of haematological diseases and malignant neoplasms,90 trying to combine them with a gene therapeutic strategy represents a unique and possibly potent therapeutic approach for HIV and AIDS-related ailments. As the results of HIV-infected patients who obtained autologous HSCT continued to improve, there was growing interest in genetically altered stem cells that were tolerant to HIV disease. Multiple logistical challenges have impeded the advancement of genetically modified hematopoietic stem cells as a conceivable therapeutic option for HIV/AIDS.72,73

UCLAs Eli and Edythe Broad Center for Restorative Medicine and Stem Cell Studies is one bit closer to constructing an instrument to arm the bodys immune system to attack and defeat HIV. Dr. Kitchen et al are the first ones to disclose the use of a chimeric antigen receptor (CAR), a genetically manipulated molecule, in blood-forming stem cells. In the experiment, the research team introduced a CAR gene into blood-forming stem cells, which were then moved into HIV-infected mice that had been genetically programmed. The scientists found that CAR-carrying blood stem cells efficiently transformed into fully functioning T cells that have the ability to kill HIV-infected cells in mice. The outcome was an 80-to-95 percentage reduction in HIV levels, suggesting that stem-cell-based genetic engineering with a CAR might be a viable and effective approach for treating HIV infection among humans. The CAR initiative, according to Dr. Kitchen, is much more able to adapt and ultimately more efficient, which can conceivably be used by others. If any further experiment showcases keep promising, the scientists expect that a practice based on their strategy will be accessible for clinical development within the next 510 years.91

HSCT and HAART therapeutic approaches in treating HIV/AIDS as the emergence of highly active antiretroviral therapy (HAART) in the 1990s improved survival rates of HIV infection, leading to a major dramatic drop in the occurrence of AIDS and AIDS-related mortalities. As an outcome, there is much less involvement with using HSCT as a therapy for HIV infection.28,33,43,67,86

A randomized clinical trial of human umbilical cord mesenchymal stem cell transplant among HIV/AIDS immunological non responders investigation, the researchers examined the clinical efficacy of transfusion of human umbilical cord mesenchymal stem cells (hUC-MSC) for immunological non-responder clients with long-term HIV disease who have an unmet medical need in the aspect of effective antiretroviral therapy. From May 2013 to March 2016, 72 HIV-infected participants were admitted in this stage of the randomized, double-blind, multi-center, placebo-controlled dose-determination investigation. They were either given a high dose of hUC-MSC of 1.5106/kg body weight as well as small doses of hUC-MSC of 0.5106/kg body weight, or a placebo application. During the 96-week follow-up experiment, interventional and immunological character traits were analysed. They found that hUC-MSC therapy was both safe and efficacious among humans. There was a significant rise in CD4+ T counts after 48 weeks of treatment in both the high-dose (P 0.001) and low-dose (P 0.001) groups, but no changes in the comparison group.92

One interesting invention made by a team of UC Davis investigators is the recognition of a particular form of stem cell that can minimize the quantity of the virus that tends to cause AIDS, thus dramatically increasing the bodys antiviral immune activity. Mesenchymal stem/stromal cells (MSCs) furnish an incredible opportunity for a creative and innovative, multi-pronged HIV cure strategic plan by augmenting prevailing HIV potential treatments. Even while no antivirals have been used, MSCs have been able to increase the hosts antiviral responses. MSC therapeutic approaches require specialized delivery systems and good cell quality regulation. The studys findings lay the proper scientific foundation for future research into MSC in the ongoing treatment of HIV and other contagious diseases in the clinical organization.35

Infection with HIV-1 necessitates the existence of both specific receptors and a chemokine receptor, particularly chemokine receptor 5 (CCR5).46 Resistance to HIV-1 infection is attained by homozygozygozity for a 32-bp removal in the CCR5 allele.93 In this investigation, stem cells were transplanted in a patient with severe myeloid leukaemia and HIV-1 infection from a donor who was homozygous to Chemokine receptor 5 delta 32. The client seemed to have no viral relapses after 20 months of transplantation and attempting to stop antiretroviral medicine. This finding highlights the essential role that CCR5 tries to play in HIV-1 infection maintenance.86

In comparison, additional HIV-1-infected people who have received allogeneic stem cell transplants with cells from CCR5 truly wild donors did not have long-term relapses from HIV-1 rebound, with 2 of these patients trying to report viral reoccurrence 12 as well as 32 weeks after analytic treatment interruption, respectively. Among these 2 patients, allogeneic stem cell transplantation probably reduced but did not eliminate latently HIV-infected cells, enabling persistent viral reservoirs to activate viral rebound. This viewpoint may not rule out the potential that allogeneic hematopoietic stem cell transplantation might result in a much more comprehensive or near-complete elimination of viral reservoirs, enabling long-term drug-free relapse of HIV-1 infection in some contexts.84 As just one report demonstrated a decade earlier, a curative treatment for HIV-1 remained elusive. The Berlin Patient has undergone 2 allogeneic hematopoietic stem cell transplantations to cure his acute myeloid leukaemia utilizing a potential donor with a homozygous genetic mutation in HIV coreceptor CCR5 (CCR532/32).15,34,46,64,65,72,82,84,86,9496 Other similar studies with CCR5 receptor targets are as follows: Automated production of CCR5-negative CD4+-T cells in a GMP compatible, clinical scale for treatment of HIV-positive patients,97 Mechanistic Models Predict Efficacy of CCR5-Deficient Stem Cell Transplants in HIV Patient Populations,98 Conditional suicidal gene with CCR5 knockout.99

Clustered regularly interspaced short palindromic repeats CRISPR/Cas9 is a promising gene editing approach that can edit genes for gain-of-function or loss-of-function mutations in order to address genetic abnormalities. Despite the fact that other gene editing techniques exist, CRISPR/Cas9 is the most reliable and efficient proven method for gene rectification.100103

Genome engineering employing CRISPR/Cas has proven to be a strong method for quickly and accurately changing specific genomic sequences. The rise of innovative haematopoiesis research tools to examine the complexity of hematopoietic stem cell (HSC) biology has been fuelled by considerable advancements in CRISPR technology over the last five years. High-throughput CRISPR screenings using many new flavours of Cas and sequential and/or functional outcomes, in specific, have become more effective and practical.104,105

The power of the CRISPR/Cas system is that it can specifically and efficiently target sequences in the genome with just a single synthetic guide RNA (sgRNA) and a single protein. Cas9 is directed to the specific DNA sequence by the sgRNA, which causes double stranded breaks and activates the cells DNA repair processes. Non-homologous end joining can cause insertiondeletion (indel) substitutions at the target location, whereas homology-directed repair can use a template DNA to insert new genetic material.104,106

The possibility for CRISPR/Cas9 to be used in the hematopoietic system was emphasised as pretty shortly after it was initiated as a new genome editing method.106,107 The efficiency with which CRISPR-mediated alteration can be used to evaluate hematopoietic stem/progenitor and mature cell function via transplantation. As a result, hematopoietic research has significantly advanced with the implementation of these technologies. Whilst single-gene CRISPR/Cas9 programming is a significant tool for testing gene function in primary hematopoietic cells, high-throughput screenings potentially offer CRISPR/Cas9 an even greater advantage in hematopoietic research.104

While understanding human haematological disorders requires the ability to mimic diseases, the ultimate goal is to transfer this innovation into therapies. Despite significant advancements in CRISPR technology, there are still barriers to overcome before CRISPR/Cas9 can be used effectively and safely in humans. CRISPR has also been used to target CCR5 in CD34+ HSPCs in an effort to make immune cells resistant to HIV infection, as CCR5 is an important coreceptor for HIV infection.104

CRISPR is a modern genome editing technique that could be used to treat immunological illnesses including HIV. The utilization of CRISPR in stem cells for HIV-related investigation, on the other end, was ineffective, and much of the experiment was done in vivo. The new research idea is about increasing CRISPR-editing efficiencies in stem cell transplantation for HIV treatment, as well as its future perspective. The possible genes that enhance HIV resistance and stem cell engraftment should be explored more in the future studies. To strengthen HIV therapy or resistance, double knockout and knock-in approaches must be used to build a positive engraftment. In the future, CRISPR/SaCas9 and Ribonucleoprotein (RNP) administration should be explored in the further investigations.108 As well as some different title studies were explained the effectiveness of the CRISPR gene editing technology on the management of HIV/AIDS including: CRISPR view of hematopoietic stem cells: Moving innovative bioengineering into the clinic,104 CRISPR-Edited Stem Cells in a Patient with HIV and Acute Lymphocytic Leukaemia,109 Sequential LASER ART and CRISPR Treatments Eliminate HIV-1 in a Subset of Infected Humanized Mice,110 Extinction of all infectious HIV in cell culture by the CRISPR-Cas12a system with only a single crRNA,111 HIV-specific humoral immune responses by CRISPR/Cas9-edited B cells,112 CRISPR-Cas9 Mediated Exonic Disruption for HIV-1 Elimination,113 RNA-directed gene editing specifically eradicates latent and prevents new HIV-1 infection,114 CRISPR/Cas9 Ablation of Integrated HIV-1 Accumulates Pro viral DNA Circles with Reformed Long Terminal Repeats,115 CRISPR-Cas9-mediated gene disruption of HIV-1 co-receptors confers broad resistance to infection in human T cells and humanized mice,116 Inhibition of HIV-1 infection of primary CD4+ T-cells by gene editing of CCR5 using adenovirus-delivered CRISPR/Cas9,117 Transient CRISPR-Cas Treatment Can Prevent Reactivation of HIV-1 Replication in a Latently Infected T-Cell Line,118 CCR5 Gene Disruption via Lentiviral Vectors Expressing Cas9 and Single Guided RNA Renders Cells Resistant to HIV-1 Infection,119 CRISPR/Cas9-Mediated CCR5 Ablation in Human Hematopoietic Stem/Progenitor Cells Confers HIV-1 Resistance In Vivo.109

Induced pluripotent stem cells (iPSCs) have significantly advanced the field of regenerative medicine by allowing the generation of patient-specific pluripotent stem cells from adult individuals. The progress of iPSCs for HIV treatment has the potential to generate a continuous supply of therapeutic cells for transplantation into HIV-infected patients. The title of the study is reported on Generation of HIV-1 Resistant and Functional Macrophages from Hematopoietic Stem Cellderived Induced Pluripotent Stem Cells. In this investigation, researchers used human hematopoietic stem cells (HSCs) to produce anti-HIV gene expressing iPSCs for HIV gene therapy. HSCs were dedifferentiated into constantly growing iPSC lines using 4 reprogramming factors and a combination anti-HIV lentiviral vector comprising a CCR5 shRNA and a human/rhesus chimeric TRIM5 gene. After directing the anti-HIV iPSCs toward the hematopoietic lineage, a large number of colony-forming CD133+ HSCs were acquired. These cells were distinguished further into functional end-stage macrophages with a normal phenotypic profile. Upon viral challenge, the anti-HIV iPSC-derived macrophages displayed good protection against HIV-1 infection. Researchers have clearly shown how iPSCs can establish into HIV-1 resistant immune cells and explain their prospective use in HIV gene and cellular therapies.120

Some other similar titles of the studies reported on the effectiveness of IPSCs on HIV/AIDS managements are as follows: Generation of HIV-Resistant Macrophages from IPSCs by Using Transcriptional Gene Silencing and Promoter-Targeted RNA,121 Generation of HIV-1-infected patients gene-edited induced pluripotent stem cells using feeder-free culture conditions,122 A High-Throughput Method as a Diagnostic Tool for HIV Detection in Patient-Specific Induced Pluripotent Stem Cells Generated by Different Reprogramming Methods,123 Genetically edited CD34+ cells derived from human iPS cells in vivo but not in vitro engraft and differentiate into HIV-resistant cells,124 Engineered induced-pluripotent stem cell-derived monocyte extracellular vesicles alter inflammation in HIV humanized mice,125 Sustainable Antiviral Efficacy of Rejuvenated HIV-Specific Cytotoxic T Lymphocytes Generated from Induced Pluripotent Stem Cells.126

Recently, one HIV patient appeared to be virus-free after having undergone a stem-cell transfusion in which their WBCs were changed with HIV-resistant variations.84 Timothy Ray Brown also noted as the Berlin patient, who is still virus-free, was the first individual to undertake stem-cell transplantation a decade earlier. The most recent patient, like Brown, had a type of leukaemia that was vulnerable to chemo treatments. They required a bone marrow transplantation, which involved removing their blood cells and replacing them with stem cells from a donor cell.5,31,34,41,127130 Rather than simply choosing a suitable donor, Ravindra Gupta et al chose one who already had 2 copies of a mutant within the CCR5 gene,128,131 which provides resistance to HIV infection.3

Additionally, this gene encodes for a specific receptor of white blood cells that are assisted in the bodys immunological responses. The transplant, according to Guptas team, completely replaced the clients White cells with HIV-resistant forms.41,83 Cells in the patients blood disrupted expressing the CCR5 receptor, making it unfeasible for the clients form of HIV to infect the above cells again. The scientists determined that the virus had been cleared from the patients blood after the transplantation. Besides that, after 16 months, the client has withdrawn antiretroviral treatment. The infection was not detected in the most recent follow-up, which occurred 18 months after the treatment was discontinued. Adam, also known as the London patient, was the second person to be cured of HIV as a result of a stem cell transfusion. This discovery is an important step forward in HIV research because it may aid in the detection of potential future therapeutic interventions. It must be noted, but even so, that this is not an extensively used HIV treatment. For HIV-infected patients, antiretroviral drugs have been the foremost therapeutic option.3,31,41,94,129,130 It also encourages many investigators and clinicians to look at the use of stem cells in the treatment of a wide range of serious medical conditions. The reprogramming abilities of stem cells, as well as their accessibility, have created a window of opportunity in medical research. The clinical utility of stem cells is forecast to expand rapidly in the coming years.

On Feb 15, 2022, scientific researchers confirmed that a woman had become the 3rd person in history to be successfully treated for HIV, the virus that causes AIDS, after just receiving a stem-cell transfusion that has used cells from cord blood. Within those transplant recipients, adult hematopoietic stem cells have been used; these are stem cells that eventually develop into all blood cell types, which include white blood cells, these are a vital component of the immune framework. Even so, the woman who had fairly recently been completely cured of HIV infection had a more unique experience than that of the 2 men who were actually cured before her.132

The clients physician, Dr. JingMei Hsu of Weill Cornell Medicine in New York, informed them that, she had been discharged from the hospital just 17 days after her procedure was performed, even with no indications of graft vs host ailment. The woman was HIV-positive but also had acute myeloid leukaemia, a blood cancer of the bone marrow that affects blood-forming cells. She had likely received cord blood as a successful treatment for both her cancer and HIV once her doctors decided on a potential donor well with HIV-blocking gene mutation. Cord blood comprises a high accumulation of hematopoietic stem cells; the blood is obtained during a childs birth and donated by the parents.132

The patients donor was partly nearly matched, and she received stem cells from a close family member to enhance her immune function after the transfusion. The procedure was performed on the woman in August of 2017. She chose to discontinue taking antiretroviral drugs, the standardized HIV intervention, 37 months upon her transfusion. After more than 14 months, there is no evidence of the viral infection or antibodies against it in her blood. Umbilical cord blood, in reality, is much more commonly accessible and simpler to try to match to beneficiaries than bone marrow. Perhaps, some research suggests that the method could be more available to HIV patients than bone marrow transplantation. Nearly 38 million people worldwide are infected with HIV. The potential for using partly matched umbilical cord blood transplantation increases the chances of choosing appropriate suitable donors for these clients considerably.132

It is really exciting to see the earlier terminally ill diseases of being effectively treated. In recent times, there has been a surge of focus on stem cell research.3 Stem cell therapy advancements in inpatient care are receiving a growing amount of attention.20 HIV/AIDS has been and remains a significant health concern around the world. Effective control of the HIV pandemic will necessitate a thorough understanding of the viruss transmission.32

Despite concerns about full compliance and adverse reactions, HAART has demonstrated to be able to succeed and is a sign specifically targeted form of treatment against HIV advancement. As illustrated by the first case of HIV infection relapse attained by bone marrow transplant, anti-HIV HPSC-based stem cell treatment and genotype technology have established a possible future upcoming technique to try to combat HIV/AIDS.

Investigators have conducted experiments with engineering distinct anti-HIV genetic traits trying to target different phases of HIV infection utilizing advanced scientific modalities. In numerous in vivo and in vitro animal studies, HSPCs and successive mature cells were secured from HIV infection by trying to target genetic factors in the infection. Anti-HIV gene engineering of HSPCs is safe and efficacious.15

The number of stem-cell-based research trials has risen in recent years. Thousands of studies claiming to use stem cells in experimental therapies have been registered worldwide. Despite some promising results, the majority of clinical stem cell technologies are still in their early life. These achievements have drawn attention to the possibility of the potential and advancement of various promising stem cell treatments currently in development.11

HIV remains a major danger to humanity. This virus has developed the ability to evade antiretroviral medication, resulting in the death of individuals. Scientists are constantly looking for a treatment for HIV/AIDS that is both effective and efficient.52 The 1st treatments in HIV+ clients were conducted in the early 1980s, even though they were cognizant of their viral disease. Following these early cases, allogeneic SCT was used to treat HIV+ patients with associated cancer or other haematological disorders all over the world. Stem cell transplantation developments have also stimulated the improvement of innovative HIV therapeutic approaches, especially for large goals like eradication and relapse.60

Numerous stem cell therapy progressions have been recognized with autologous and allogeneic hematopoietic stem cell transplantation, as well as umbilical cord blood mesenchymal stem cell transplant in AIDS immunologic non-responders. Whereas this sector continues to advance and distinguishing directives for these cells become much more effective, totipotent stem cells such as hESC and the recently reported induced pluripotent stem cells (iPSC) could be very useful for genetic engineering methods to counter hematopoietic abnormalities such as HIV disease.133135

Immunocompromised people are at a higher risk of catching life-threatening diseases. The perseverance of latently infected cells, which is formed by viral genome inclusion into host cell chromosomes, is a significant challenge in HIV-1 elimination. Stem cell therapy is producing impressive patient outcomes, illustrating not only the broad relevance of these strategies but also the huge potential of cell and gene treatment using adult stem cells and somatic derivative products of pluripotent stem cells (PSCs).

Stem cells have enormous regeneration capacity, and a plethora of interesting therapeutic uses are on the frontier. This is a highly interdisciplinary scientific field. Evolutionary biologists, biological technicians, mechanical engineers, and others that have evolved novel concepts and decided to bring them to medical applications are required to make important contributions. Further to that, recent advancements in several different research areas may contribute to stem cell application forms that are novel. Several hurdles must be conquered, however, in the advancement of stem cells. On the other hand, this discipline appears to be a promising and rapidly expanding research area.

Stem cell-based approaches to HIV treatment resemble an innovative approach to trying to rebuild the ravaged bodys immune system with the utmost goal of eliminating the virus from the body. We will probably see effective experiments from the next new generation of stem cell-based strategies shortly, which will start serving as a base for the further development and use of these techniques in a range of treatment application areas for other chronic diseases.

My immense pleasure was mentioned to family members and friends, who supported and encouraged me in every activity.

There was no funding for this work.

The authors declare that they have no conflicts of interest in relation to this work.

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2. Nadig RR. Stem cell therapy hype or hope? A review. J Conserv Dent JCD. 2009;12:131138. doi:10.4103/0972-0707.58329

3. Tasnim KN, Adrita SH, Hossain S, Akash SZ, Sharker S. The prospect of stem cells for HIV and cancer treatment: a review. Pharm Biomed Res. 2020;6:1726.

4. Weissman IL. Translating stem and progenitor cell biology to the clinic: barriers and opportunities. Science. 2000;287:14421446. doi:10.1126/science.287.5457.1442

5. Pernet O, Yadav SS, An DS. Stem cellbased therapies for HIV/AIDS. Adv Drug Deliv Rev. 2016;103:187201. doi:10.1016/j.addr.2016.04.027

6. Kolios G, Moodley Y. Introduction to stem cells and regenerative medicine. Respir Int Rev Thorac Dis. 2013;85:310.

7. Ebrahimi A, Ahmadi H, Ghasrodashti ZP, et al. Therapeutic effects of stem cells in different body systems, a novel method that is yet to gain trust: a comprehensive review. Bosn J Basic Med Sci. 2021;21:672701. doi:10.17305/bjbms.2021.5508

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14. Bobba S, Di Girolamo N, Munsie M, et al. The current state of stem cell therapy for ocular disease. Exp Eye Res. 2018;177:6575. doi:10.1016/j.exer.2018.07.019

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17. Prentice DA. Adult Stem Cells. Circ Res. 2019;124:837839. doi:10.1161/CIRCRESAHA.118.313664

18. McKee C, Chaudhry GR. Advances and challenges in stem cell culture. Colloids Surf B Biointerfaces. 2017;159:6277. doi:10.1016/j.colsurfb.2017.07.051

19. Prez Lpez S, Otero Hernndez J. Advances in stem cell therapy. In: Lpez-Larrea C, Lpez-Vzquez A, Surez-lvarez B, editors. Stem Cell Transplantation. New York, NY: Springer US; 2012:290313.

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PROMISING STEM CELL THERAPY IN THE MANAGEMENT OF HIV & AIDS | BTT - Dove Medical Press

From cities in the sky to robot butlers, futuristic visions fill the history ofPopSci. In theAre we there yet?column we check in on progress towards our most ambitious promises. Read the series and explore all our 150th anniversary coveragehere.

In 1923, Popular Science reported that people were drinking radium-infused water in an attempt to stay young. How far have we come to a real (and non-radioactive) cure for aging?

From the time Marie Curie and her husband Pierre discovered radium in 1898, it was quickly understood that the new element was no ordinary metal. When the Curies finally isolated pure radium from pitchblende (a mineral ore) in 1902, they determined that the substance was a million times more radioactive than uranium. At the time, uranium was already being used in medicine to X-ray bones and even treat cancer tumors, a procedure first attempted in 1899 by Tage Sjogren, a Swedish doctor. Coupled with radiums extraordinary radioactivity and unnatural blue glow, the mineral was soon touted as a cure for everything including cancer, blindness, and baldness, even though radioactivity had only been used to treat malignant tumors. As Popular Science reported in June 1923, it was even believed that a daily glassful of radium-infused water would restore youth and extend life, making it the latest in a long line of miraculous elixirs.

By May 1925 The New York Times was among the first to report cancer cases linked to radium. Two years later, five terminally ill women, who became known as the Radium Girls, sued the United States Radium Corporation where they had worked, hand-painting various objects with the companys poisonous pigment. As more evidence emerged of radiums carcinogenic effects, its cure-all reputation quickly faded, although it would take another half-century before the last of the luminous-paint processing plants was shut down. Radium is still used today in nuclear medicine to treat cancer patients, and in industrial radiography to X-ray building materials for structural defectsbut its baseless status as a life-extending elixir was short-lived.

And yet, radiums downfall did not end the true quest for immortality: Our yearning for eternal youth continues to inspire a staggering range of scientifically dubious products and services.

Since the early days of civilization, when Sumerians etched one of the first accounts of a mortal longing for eternal life in the Epic of Gilgamesh on cuneiform tablets, humans have sought a miracle cure to defy aging and defer death. Five thousand years ago in ancient Egypt, priests practiced corpse preservation so a persons spirit could live on in its mummified host. Fortunately, anti-aging biotech has advanced from mummification and medieval quests for the fountain of youth, philosophers stone, and holy grail, as well as the perverse practices of sipping metal-based elixirs, bathing in the blood of virgins, and even downing Radium-infused water in the early 20th century. But what hasnt changed is that the pursuit of eternal youth has largely been sponsored by humankinds wealthiest citizens, from Chinese emperors to Silicon Valley entrepreneurs.

Weve all long recognized that aging is the greatest risk factor for the overwhelming majority of chronic diseases, whether it be Alzheimers disease, cancer, osteoporosis, cardiovascular diseases, or diabetes, says Nathan LeBrasseur, co-director of The Paul F. Glenn Center for Biology of Aging Research at the Mayo Clinic in Minnesota. But weve really kind of said, well, theres nothing we can do about senescence [cellular aging], so lets move on to more prevalent risk factors that we think we can modify, like blood pressure or high lipids. In the last few decades, however, remarkable breakthroughs in aging research have kindled interest and opened the funding spigots. Fortunately, the latest efforts have been grounded in more established scienceand scientific methodsthan was available in radiums heyday.

In the late 19th century, just as scientists began zeroing in on germs with microscopes, evolutionary biologist August Weismann delivered a lecture on cellular aging, or senescence. The Duration of Life (1881) detailed his theory that cells had replication limits, which explained why the ability to heal diminished with age. It would take 80 years to confirm Weismanns theory. In 1961, biologists Leonard Hayflick and Paul Moorhead observed and documented the finite lifespan of human cells. Another three decades later, in 1993, Cynthia Kenyon, a geneticist and biochemistry professor at the University of California, San Francisco, discovered how a specific genetic mutation in worms could double their lifespans. Kenyons discovery gave new direction and hope to the search for eternal youth, and wealthy tech entrepreneurs were eager to fund the latest quest: figuring out how to halt aging at the cellular level. (Kenyon is now vice president of Calico Research Labs, an Alphabet subsidiary.)

Weve made such remarkable progress in understanding the fundamental biology of aging, says LeBrasseur. Were at a new era in science and medicine, of not just asking the question, what is it about aging that makes us at risk for all these conditions? But also is there something we can do about it? Can we intervene?

In modern aging research labs, like LeBrasseurs, the focus is to tease apart the molecular mechanisms of senescence and develop tools and techniques to identify and measure changes in cells. The ultimate goal is to discover how to halt or reverse the changes at a cellular level.

But the focus on the molecular mechanisms of aging is not new. In his 1940 book, Organisers and Genes, theoretical biologist Conrad Waddington offered a metaphor for a cells life cyclehow it grows from an embryonic state to something specific. In Waddingtons epigenetic landscape, a cell starts out in its unformed state at the top of a mountain with the potential to roll downhill in any direction. After encountering a series of forks, the cell lands in a valley, which represents the tissue it becomes, like a skin cell or a neuron. According to Waddington, epigenetics are the external mechanisms of inheritanceabove and beyond standard genetics, such as chemical or environmental factorsthat lead the cell to roll one way or another when it encounters a fork. Also according to Waddington, who first proposed the theory of epigenetics, once the cell lands in its valley, it will remain there until it diesso, once a skin cell, always a skin cell. Waddington viewed cellular aging as a one-way journey, which turns out to be not so accurate.

We know now that even cells of different types keep changing as they age, says Morgan Levine, who until recently led her own aging lab at the Yale School of Medicine, but is now a founding principal investigator at Altos Labs, a lavishly funded startup. The [Waddington] landscape keeps going. And the new exciting thing is reprogramming, which shows us that you can push the ball back the other way.

Researchers like Levine continue to discover new epigenetic mechanisms that can be used to not only determine a cells age (epigenetic or biological clock) but also challenge Waddingtons premise that a cells life is one way. Cellular reprogramming is an idea first attempted in the 1980s and later advanced by Nobel Prize recipient Shinya Yamanaka, who discovered how to revert mature, specialized cells back to their embryonic, or pluripotent, state, enabling them to start fresh and regrow, for instance, into new tissue like liver cells or teeth.

I like to think of the epigenome as the operating system of a cell, Levine explains. So more or less all the cells in your body have the same DNA or genome. But what makes the skin cell different from a brain cell is the epigenome. It tells a cell which part of the DNA it should use thats specific to it. In sum, all cells start out as embryonic or stem cells, but what determines a cells end state is the epigenome.

Theres been a ton of work done with cells in a dish, Levine adds, including taking skin cells from patients with Alzheimers disease, converting them back to stem cells, and then into neurons. For some cells, you dont always have to go back to the embryonic stem cell, you can just convert directly to a different cell type, Levine says. But she also notes that what works in a dish is vastly different from what works in living specimens. While scientists have experimented with reprogramming cells in vivo in lab animals with limited success, the ramifications are not well understood. The problem is when you push the cells back too far [in their life cycle], they dont know what theyre supposed to be, says Levine. And then they turn into all sorts of nasty things like teratoma tumors. Still, shes hopeful that many of the problems with reprogramming may be sorted out in the next decade. Levine doesnt envision people drinking cellular-reprogramming cocktails to stave off agingat least not in the foreseeable futurebut she does see early-adopter applications for high-risk patients who, lets say, can regrow their organs instead of requiring transplants.

While the quest for immortality is still funded largely by the richest of humans, it has morphed from the pursuit of mythical objects, miraculous elements, and mystical rituals to big business, raising billions to fund exploratory research. Besides Calico and Altos Labs (funded by Russian-born billionaire Yuri Milner and others), theres Life Biosciences, AgeX Therapeutics, Turn Biotechnologies, Unity Biotechnology, BioAge Labs, and many more, all founded in the last decade. While theres considerable hype for these experimental technologies, any actual products and services will have to be approved by regulatory agencies like the Food and Drug Administration, which did not exist when radium was being promoted as a cure-all in the US.

While were working on landing long-term moon shots like editing genomes with CRISPR and reprogramming epigenomes to halt or reverse aging, LeBrasseur sees near-term possibilities in repurposing existing drugs to prop up senescent cells. When a cell gets old and damaged, it has one of three choices: to succumb, in which case it gets flushed from the system; to repair itself because the damage is not so bad; or to stop replicating and hang around as a zombie cell. Not only do [zombie cells] not function properly, explains LeBrasseur, but they secrete a host of very toxic molecules known as senescence associated secretory phenotype, or SASP. Those toxic molecules trigger inflammation, the precursor to many diseases.

It turns out there are drugs, originally targeted at other diseases, that are already in anti-aging trials because theyve shown potential to impact cell biology at a fundamental level, effectively staving off senescence. Although rapamycin was originally designed to suppress the immune system in organ transplant patients, and metformin to assist diabetes patients, both have shown anti-aging promise. When you start looking at data from an epidemiological lens, you recognize that these individuals [like diabetes patients taking metformin] often have less cardiovascular disease, notes LeBrasseur. They also have lower incidence of cancer, and theres some evidence that they may even have lower incidence of Alzheimers disease. Even statins (for cardiovascular disease) and SGL2 inhibitors (another diabetes drug) are being explored for a possible role in anti-aging. Of course, senescence is not all bad. It plays an important role, for example, as a protective mechanism against the development of malignant tumorsso tampering with it could have its downsides. Biology is so smart that weve got to stay humble, right? says LeBrasseur.

Among other things, the Radium Girls taught us to avoid the hype and promise of new and unproven technologies before the pros and cons are well understood. Weve already waited millennia for a miracle elixir, making some horrific choices along the way, including drinking radioactive water as recently as a century ago. The 21st century offers its own share of anti-aging quackery, including unregulated cosmetics, questionable surgical procedures, and unproven dietary supplements. While we may be closer than weve ever been in human history to real solutions for the downsides of aging, there are still significant hurdles to overcome before we can reliably restore youth. It will take years or possibly decades of research, followed by extensive clinical trials, before todays anti-aging research pays dividendsand even then its not likely to come in the form of a cure-all cocktail capable of bestowing immortality. In the meantime, LeBrasseurs advice is simple for those who can afford it: You dont have to wait for a miracle cure. Lifestyle choices like physical activity, nutritional habits, and sleep play a powerful role on our trajectories of aging. You can be very proactive today about how well you age. Unfortunately, not everyone has the means to follow LeBrasseurs medical wisdom. But the wealthiest among usincluding those funding immortalitys questmost definitely do.

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Radium was once cast as an elixir of youth. Are todays ideas any better? - Popular Science

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How calming our spinal cords could provide relief from muscle spasmsAn Edith Cowan University (ECU) studyinvestigating motoneurons in the spine has revealed two methods can make our spinal cords less excitable and could potentially be usedto treat muscle spasms.

Analysis Finds Government Websites Downplay PFAS Health RisksState and federal public health agencies often understate the scientific evidence surrounding the toxicity of per- and polyfluoroalkyl substances (PFAS) in their public communications, according toan analysispublished today in the journalEnvironmental Health.

Multiple diagnoses are the norm with mental illness; new genetic study explains whyThe study, published this weekin the journalNature Genetics, found that while there is no gene or set of genes underlying risk for all of them, subsets of disordersincluding bipolar disorder and schizophrenia; anorexia nervosa and obsessive-compulsive disorder; and major depression and anxietydo share a common genetic architecture.

Drinkers sex plus brewing method may be key to coffees link to raised cholesterolThe sex of the drinker as well as the brewing method may be key to coffees link with raised cholesterol, a known risk factor for heart disease, suggests research published in the open access journalOpen Heart.

Artificial cell membrane channels composed of DNA can be opened and locked with a keyIn new research, Arizona State University professorHao Yan, along with ASU colleagues and international collaborators from University College London describe the design and construction of artificial membrane channels, engineered using short segments of DNA.

Single cell RNA sequencing uncovers new mechanisms of heart diseaseResearchers at the Hubrecht Institute have now successfully applied a new revolutionary technology (scRNA-seq) to uncover underlying disease mechanisms, including specifically those causing the swelling.

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Other Notable Health Studies & Research From May 11, 2022 - Study Finds

One is that there are some people that are naturally resistant to heart attack and have lifelong, low levels of LDL, the cardiologist says. Second, there are some genes that can be switched off that lead to very low LDL cholesterol, and individuals with those genes switched off are resistant to heart attacks.

Kathiresan and his team formed a hypothesis in 2016 that if they could develop a medicine that mimics the natural protection that some people enjoy, then they might identify a powerful new way to treat and ultimately prevent heart attacks. They launched Verve in 2018 with the goal of creating a one-time therapy that would permanently lower LDL and eliminate heart attacks caused by high LDL.

The medication is targeted specifically for patients who have a genetic form of high cholesterol known as heterozygous familial hypercholesterolemia, or FH, caused by expression of a gene called PCSK9. Verve also plans to develop a program to silence a gene called ANGPTL3 for patients with FH and possibly those with or at risk of atherosclerotic cardiovascular disease.

FH causes cholesterol to be high from birth, reaching levels of 200 to 300 milligrams per deciliter. Suggested normal levels are around 100 to 129 mg/dl, and anything above 130 mg/dl is considered high. Patients with cardiovascular disease usually are asked to aim for under 70 mg/dl, but many still have unacceptably high LDL despite taking oral medications such as statins. They are more likely to have heart attacks in their 30s, 40s and 50s, and require lifelong LDL control.

The goal for drug treatments for high LDL, Kathiresan says, is to reduce LDL as low as possible for as long as possible. Physicians and researchers also know that a sizeable portion of these patients eventually start to lose their commitment to taking their statins and other LDL-controlling medications regularly.

If you ask 100 patients one year after their heart attack what fraction are still taking their cholesterol-lowering medications, its less than half, says Kathiresan. So imagine a future where somebody gets a one-time treatment at the time of their heart attack or before as a preventive measure. Its right in front of us, and its something that Verve is looking to do.

In late 2020, Verve completed primate testing with monkeys that had genetically high cholesterol, using a one-time intravenous injection of VERVE-101. It reduced the monkeys LDL by 60 percent and, 18 months later, remains at that level. Kathiresan expects the LDL to stay low for the rest of their lives.

Verves gene editing medication is packaged in a lipid nanoparticle to serve as the delivery mechanism into the liver when infused intravenously. The drug is absorbed and makes its way into the nucleus of the liver cells.

Verves program targeting PCSK9 uses precise, single base, pair base editing, Kathiresan says, meaning it doesn't cut DNA like CRISPR gene editing systems do. Instead, it changes one base, or letter, in the genome to a different one without affecting the letters around it. Comparing it to a pencil and eraser, he explains that the medication erases out a letter A and makes it a letter G in the A, C, G and T code in DNA.

By making that simple change from A to G, the medication switches off the PCSK9 gene, automatically lowering LDL cholesterol.

Once the DNA change is made, all the cells in the liver will have that single A to G change made, Kathiresan says. Then the liver cells divide and give rise to future liver cells, but every time the cell divides that change, the new G is carried forward.

Additionally, Verve is pursuing its second gene editing program to eliminate ANGPTL3, a gene that raises both LDL and blood triglycerides. In 2010, Kathiresan's research team learned that people who had that gene completely switched off had LDL and triglyceride levels of about 20 and were very healthy with no heart attacks. The goal of Verves medication will be to switch off that gene, too, as an option for additional LDL or triglyceride lowering.

Success with our first drug, VERVE-101, will give us more confidence to move forward with our second drug, Kathiresan says. And it opens up this general idea of making [genomic] spelling changes in the liver to treat other diseases.

The approach is less ethically concerning than other gene editing technologies because it applies somatic editing that affects only the individual patient, whereas germline editing in the patients sperm or egg, or in an embryo, gets passed on to children. Additionally, gene editing therapies receive the same comprehensive amount of testing for side effects as any other medicine.

We need to continue to advance our approach and tools to make sure that we have the absolute maximum ability to detect off-target effects, says Euan Ashley, professor of medicine and genetics at Stanford University and founding director of its Center for Inherited Cardiovascular Disease. Ashley and his colleagues at Stanfords Clinical Genomics Program and beyond are increasingly excited about the promise of gene editing.

We can offer precision diagnostics, so increasingly were able to define the disease at a much deeper level using molecular tools and sequencing, he continues. We also have this immense power of reading the genome, but were really on the verge of taking advantage of the power that we now have to potentially correct some of the variants that we find on a genome that contribute to disease.

He adds that while the gene editing medicines in development to correct genomes are ahead of the delivery mechanisms needed to get them into the body, particularly the heart and brain, hes optimistic that those arent too far behind.

It will probably take a few more years before those next generation tools start to get into clinical trials, says Ashley, whose book, The Genome Odyssey, was published last year. The medications might be the sexier part of the research, but if you cant get it into the right place at the right time in the right dose and not get it to the places you dont want it to go, then that tool is not of much use.

Medical experts consider knocking out the PCSK9 gene in patients with the fairly common genetic disorder of familial hypercholesterolemia roughly one in 250 people a potentially safe approach to gene editing and an effective means of significantly lowering their LDL cholesterol.

Nurse Erin McGlennon has an Implantable Cardioverter Defibrillator and takes medications, but she is also hopeful that a gene editing medication will be developed in the near future.

Erin McGlennon

Mary McGowan, MD, chief medical officer for The Family Heart Foundation in Pasadena, CA, sees the tremendous potential for VERVE-101 and believes patients should be encouraged by the fact that this kind of research is occurring and how much Verve has accomplished in a relatively short time. However, she offers one caveat, since even a 60 percent reduction in LDL wont completely eliminate the need to reduce the remaining amount of LDL.

This technology is very exciting, she said, but we want to stress to our patients with familial hypercholesterolemia that we know from our published research that most people require several therapies to get their LDL down., whether that be in primary prevention less than 100 mg/dl or secondary prevention less than 70 mg/dl, So Verves medication would be an add-on therapy for most patients.

Dr. Kathiresan concurs: We expect our medicine to lower LDL cholesterol by about 60 percent and that our patients will be on background oral medications, including statins that lower LDL cholesterol.

Several leading research centers are investigating gene editing treatments for other types of cardiovascular diseases. Elizabeth McNally, Elizabeth Ward Professor and Director at the Center for Genetic Medicine at Northwestern Universitys Feinberg School of Medicine, pursues advanced genetic correction in neuromuscular diseases such as Duchenne muscular dystrophy and spinal muscular atrophy. A cardiologist, she and her colleagues know these diseases frequently have cardiac complications.

Even though the field is driven by neuromuscular specialists, its the first therapies in patients with neuromuscular diseases that are also expected to make genetic corrections in the heart, she says. Its almost like an afterthought that were potentially fixing the heart, too.

Another limitation McGowan sees is that too many healthcare providers are not yet familiar with how to test patients to determine whether or not they carry genetic mutations that need to be corrected. We need to get more genetic testing done, she says. For example, thats the case with hypertrophic cardiomyopathy, where a lot of the people who probably carry that diagnosis and have never been genetically identified at a time when genetic testing has never been easier.

One patient who has been diagnosed with hypertrophic cardiomyopathy also happens to be a nurse working in research at Genentech Pharmaceutical, now a member of the Roche Group, in South San Francisco. To treat the disease, Erin McGlennon, RN, has an Implantable Cardioverter Defibrillator and takes medications, but she is also hopeful that a gene editing medication will be developed in the near future.

With my condition, the septum muscles are just growing thicker, so Im on medicine to keep my heart from having dangerous rhythms, says McGlennon of the disease that carries a low risk of sudden cardiac death. So, the possibility of having a treatment option that can significantly improve my day-to-day functioning would be a major breakthrough.

McGlennon has some control over cardiovascular destiny through at least one currently available technology: in vitro fertilization. Shes going through it to ensure that her children won't express the gene for hypertrophic cardiomyopathy.

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Podcast: Has the First 150-Year-Old Already Been Born - Leaps

Cell and gene therapies are poised to have a major impact on the landscape of modern medicine, carrying the potential to treat an array of different diseases with unmet clinical need.

However, the number of approved, clinically adopted cell and gene therapies is mere compared to the amount that are currently in development. A major barrier for the translation of such therapies is the safe integration of therapeutic genes into the human genome. The insertion of therapeutic genes bears the risk of off target effects, or integration of the gene into an unintended location.

A number of different strategies have been proposed to mitigate this effect. The most recent body of work comes from a collaboration between Harvards Wyss Institute for Biologically Inspired Engineering, Harvard Medical School (HMS) and the ETH Zurich in Switzerland.

Published in Cell Report Methods, the research focused on identifying safe spots in the genome. These locations, known as genomic safe harbors (GSHs), are areas in the genome that meet the following criteria: they can be accessed easily by genome-editing strategies, are within a safe distance from genes that possess functional properties and permit expression of a therapeutic gene, only once it has landed in the harbor. A simple analogy is deciding which harbor to dock a boat there are many considerations, and these depend on the type of boat you are sailing, the weather conditions and ease of access.

The research team adopted computational strategies that enabled the identification of 2,000 predicted GSHs. From this initial identification, they successfully validated two of the sites both in vitro and in vivo using reporter proteins.

Technology Networks interviewed the studys first author, Dr. Erik Aznauryan, research fellow in the laboratory of Professor George Church at Harvard Medical School. Aznauryan dives into further detail on the history of GSH research, the methods adopted to validate the GSH sites and the potential applications of this research.

Molly Campbell (MC): Can you talk about the history of genomic safe harbor research, and how they were discovered?

Erik Aznauryan (EA): Three genomic sites were empirically identified in previous studies to support stable expression of genes of interest in human cells: AAVS1, CCR5 and hRosa26. All these examples were established without any a-priori safety assessment of the genomic loci they reside in.

Attempts have been made to identify human GSH sites that would satisfy various safety criteria, thus avoiding the disadvantages of existing sites. One approach developed by Sadelain and colleagues used lentiviral transduction of beta-globin and green fluorescence protein genes into induced pluripotent stem cells (iPSCs), followed by the assessment of the integration sites in terms of their linear distance from various coding and regulatory elements in the genome, such as cancer genes, miRNAs and ultraconserved regions.

They discovered one lentiviral integration site that satisfied all of the proposed criteria, demonstrating sustainable expression upon erythroid differentiation of iPSCs. However, global transcriptome profile alterations of cells with transgenes integrated into this site were not assessed. A similar approach by Weiss and colleagues used lentiviral integrations in Chinese hamster ovary (CHO) cells to identify sites supporting long-term protein expression for biotechnological applications (e.g., recombinant monoclonal antibody production). Although this study led to the evaluation of multiple sites for durable, high-level transgene expression in CHO cells, no extrapolation to human genomic sites was carried out.

Another study aimed at identifying GSHs through bioinformatic search of mCreI sites regions targeted by monomerized version of I-CreI homing endonuclease found and characterized in green algae as capable to make targeted staggered double-strand DNA breaks residing in loci that satisfy GSH criteria. Like previous work, several stably expressing sites were identified and proposed for synthetic biology applications in humans. However, local and global gene expression profiling following integration events in these sites have not been conducted.

All these potential GSH sites possess a shared limitation of being narrowed by lentiviral- or mCreI-based integration mechanisms. Additionally, safety assessments of some of these identified sites, as well as previously established AAVS1, CCR5 and Rosa26, were carried out by evaluating the differential gene expression of genes located solely in the vicinity of these integration sites, without observing global transcriptomic changes following integration.

A more comprehensive bioinformatic-guided and genome-wide search of GSH sites based on established criteria, followed by experimental assessment of transgene expression durability in various cell types and safety assessment using global transcriptome profiling would, thus, lead to the identification of a more reliable and clinically useful genomic region.

MC: If GSHs do not encode proteins, or RNAs with functions in gene expression, or other cellular processes what is their function in the genome?

EA: In addition to protein coding, functional RNA coding, regulatory and structural regions of the human genome, other less well understood and inactive DNA regions exist.

A large proportion of the human genome seems to have evolved in the presence of a variety of integrating viruses which, as they inserted their DNA into the eukaryotic genome over the course of million years, lead to an establishment of vast non-coding elements that we continue to carry to this day. Furthermore, partial duplications of functional human genes have resulted in the formation of inactive pseudogenes, which occupy space in the genome yet are not known to bear cellular functions.

Finally, functional roles of some non-coding portions of the human genome are not well understood yet. Our search of safe harbors was conducted using existing annotation of the human genome, and as more components of it are deciphered the identification of genomic regions safe for gene insertion will become more informed.

MC: Are you able to discuss why some regions of the genome were previously regarded as GSHs but are now recognized as non-GSHs?

EA: In the absence of other alternatives, AAVS1, CCR5 and hRosa26 sites were historically called GSHs, as they supported the expression of genes of interest in a variety of cell types and were suitable for use in a research setting.

Their caveats (mainly, location within introns of functional genes, closely surrounded by other known protein coding genes as well as oncogenes) however prevent them from being used for clinical applications. Therefore, in our paper we dont call them GSHs, and refer to our newly discovered sites as GSHs.

MC: You thoroughly scanned the genome to identify candidate loci for further study as potential GSHs. Can you discuss some of the technological methods you adopted here, and why?

EA: We used several publicly available databases to identify genomic coordinates of structural, regulatory and coding components of the human genome according to the GSH criteria we outlined in the beginning of our study (outside genes, oncogenes, lncRNAs etc.,). We used these coordinates and bioinformatic tools such as command lines bedtools to exclude these genomic elements as well as areas adjacent to them. This left us with genomic regions putative GSHs from which we could then experimentally validate by inserting reporter and therapeutic genes into them followed by transcriptomic analysis of GSH-integrated vs non-integrated cells.

MC: You narrowed down your search to test five, and then two GSHs. Can you expand on your choice of reporter gene when assessing two GSHs in cell lines?

EA: Oftentimes in research you go with what is available or what is of the most interest to the lab you are currently working in.

Our case was not an exception, and we initially (up until the T cell work) used the mRuby reporter gene as it was widely available and extensively utilized and validated in our lab at ETH Zurich back then.

When I moved to the Wyss Institute at Harvard, I began collaborating with Dr. Denitsa Milanova, who was interested in testing these sites in the context of skin gene therapy particularly the treatment of junctional epidermolysis bullosa caused by mutations in various anchor proteins connecting different layers of skin, among which is the LAMB3 gene. For this reason, we decided to express this gene in human dermal fibroblasts, together with green fluorescent protein to have a visualizable confirmation of expression. We hope we would be able to translate this study into clinics.

MC: Can you describe examples of how GSHs can be utilized in potential therapeutics?

EA: Current cell therapy approaches rely on random insertion of genes of interest into the human genome. This can be associated with potential side effects including cancerous transformation of therapeutic cells as well as eventual silencing of the inserted gene.

We hope that current cell therapies will eventually transition to therapeutic gene insertions precisely into our GSHs, which will alleviate both described concerns. Specific areas of implementation may involve safer engineering of T cells for cancer treatment: insertion of genes encoding receptors targeting tumor cells or cytokines capable of enhancing anti-tumor response.

Additionally, these sites can be used for the engineering of skin cells for therapeutic (as discussed earlier with the LAMB3 example) as well as anti-aging applications, such as expression of genes that result in youthful skin phenotype.

Finally, given the robustness of gene expression from our identified sites, they can be used for industry-scale bio-manufacturing: high-yield production of proteins of interest in human cell lines for subsequent extraction and therapeutic applications (e.g., production of clotting factors for patients with hemophilias).

MC: Are there any limitations to the research at this stage?

EA: A primary limitation to this study is the low frequency of genomic integration events using CRISPR-based knock-in tools. This means that cells in which the gene of interest successfully integrated into the GSH must be pulled out of the vastly larger population of cells without this integration.

These isolated cells would then be expanded to generate homogenous population of gene-bearing cells. Such pipeline is not ideal for a clinical setting and improvements in gene integration efficiencies are needed to help this technology easier translate into clinics.

Our lab is currently working on developing genome engineering tools which would eventually allow to integrate large genes into GSHs with high precision and efficiency.

MC: What impact might this study have on the cell and gene therapy development space?

EA: This study will hopefully lead to many researchers in the field testing our sites, validating them in other therapeutically relevant cell types and eventually using them in research as well as in clinics as more reliable, durable and safe alternatives to current viral based random gene insertion methods.

Additionally, since in our work we shared all putative GSHs identified by our computational pipeline, we hope researchers will attempt to test sites we havent validated yet by implementing the GSH evaluation pipeline that we outlined in the paper. This will lead to identification of more GSHs with perhaps even better properties for clinical translation or bio-manufacturing.

MC: What are your next steps in advancing this work?

We hope to one day translate our successful in vitro skin results and start using these GSHs in an in vivo context.

Additionally, we are looking forward to improving integration efficiencies into our GSHs, which would further support clinical transition of our sites.

Finally, we will evaluate the usability of our GSHs for large-scale production of therapeutically relevant proteins, thus ameliorating the pipeline of manufacturing of biologics.

Dr. Erik Aznauryan was speaking to Molly Campbell, Senior Science Writer for Technology Networks.

Link:
Sailing the Genome in Search of Safe Harbors - Technology Networks

Genome Editing Market: Snapshot

Genome editing tools have come a long way from the mid-twentieth century. In 1970s and 1980s, gene targeting was done using largely homologous combination, but was only possible in mice. Since then, the expanding science of genetic analysis and manipulation extended to all types of cells and organisms. Advent of new tools helped scientists achieve targeted DNA double-strand break (DSB) in the chromosome, and is a key pivot on which revenue generation in the genome editing market prospered. New directions for programmable genome editing emerged in the decades of the twenty-first century, expanding the arena.

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Cutting-edge platforms at various points in time continue to enrich genome editing market. Various classes of nucleases emerged, most notable of which is CRISPR-Cas. Research labs around the world have extensively used the platforms in making DSBs at any target of choice. Aside from this, agricultural sciences and medical sectors make substantial use of zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs) in genome editing. Strides made in stem cell therapies, particularly in rectifying an aberrant mutation, have boosted the growth of the genome editing market. Genetic diseases such as muscular dystrophy and sickle cell disease present an incredible revenue prospect in the genome editing market. Ongoing research on novel vectors and non-vector approaches are expected to bolster the outlook of the market.

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Genomic editing refers to the strategies and techniques implemented for the modification of target genetic information of any living organism. Genome editing involves gene modification at specific areas through recombinant technology, which increases precision in insertion and decreases cell toxicity. Current advancement in genome editing is based on programmable nucleases. The genome editing market is presently witnessing significant growth due to increase in R&D expenditure, rise in government funding for genomic research, technological advancements, and growth in production of genetically modified crops. Companies have made significant investments in R&D in the past few years to develop cutting-edge technologies, such as, CRISPR and TALEN. For instance, Thermo Fisher Scientific is investing significantly in the development of its CRISPR technology for providing better efficiency and accuracy in research and also to fulfil the unmet demands in research and therapeutics. Cas9 protein and FokI protein have been combined to form a dimeric CRISPR/Cas9 RNA-guided FokI nucleases system, which is expected to have wide range of genome editing applications.

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The genome editing market is growing rapidly due to its application in a large number of areas, such as mutation, therapeutics, and agriculture biotechnology. Genome editing techniques offer large opportunities in crop improvement. However, the real potential of homologous recombination for crop improvement in targeted gene replacement therapy is yet to be realized. Homologous recombination is expected to be used as an effective methodology for crop improvement, which is not possible through transgene addition. Rise in the number of diseases and applications is likely to expand the scope of genome editing in the near future. It includes understanding the role of specific genes and processes of organ specific stem cells, such as, neural stem cells and spermatogonial stem cells. Genome editing has a significant scope to treat genetically affected cells, variety of cancers, and agents of infectious diseases such as viruses, bacteria, parasites, etc. However, genetic alteration of human germline for medicinal purpose has been debated for years. Ethical issues, comprising concern for animal welfare, can arise at all stages of generation and life span of genetically engineered animal.

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The global genome editing market can be segmented based on technology, application, end-user, and geography. In terms of technology, the genome editing market can be categorized into CRISPR, TALEN, ZFN, and other technologies. Bioinformatics has eased the process of data analysis through various technological applications. On the basis of application, the global genome editing market can be classified cell-line engineering, animal genome engineering, plant genome engineering, and others. Based on end-user, the genome editing market can be segmented into pharmaceutical and biotechnological companies and academic and clinical research organizations. In terms of region, the global genome editing market can be segmented into North America, Europe, Asia Pacific, Latin America, and Middle East & Africa. North America is projected to continue its dominance in the global genome editing market owing to high government funding for research on genetic modification in the region. Asia Pacific is a rapidly growing genome editing market due to rise in investments by key players in the region. Rise in drug discovery and development activities, coupled with increasing government initiatives toward funding small and start-up companies in the biotechnology and life sciences industry, is a major factor expected to drive the genome editing market in North America during the forecast period. Players should invest in the emerging economies and the countries of Asia-Pacific like China, South Korea, Australia, India and Singapore in which the genome editing market is expected to grow at rapid pace in future, due to growing funding in research.

Key players operating in the global genome editing market are CRISPR Therapeutics, Thermo Fisher Scientific, GenScript Corporation, Merck KgaA, Sangamo Therapeutics, Inc., Horizon Discovery Group, Integrated DNA Technologies, New England Biolabs, OriGene Technologies, Lonza Group, and Editas Medicine.

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Topical antibiotics have emerged as a popular drug class for the treatment and management of a range of medical conditions. Among different indications such as the skin, eye, and Bromhidrosis, the use of topical antibiotics to fight bacterial skin infection has witnessed consistent growth over the past few decades a trend that is expected to continue over the upcoming years. Research and development activities around the world are likely to fuel the growth of the global topical antibiotics market, as new topical antibiotics continue to enter the market. While the growing popularity of antiseptics could potentially hinder market growth, the growing awareness pertaining to the benefits of topical antibiotics is anticipated to boost the demand.

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Genome Editing Market: Rise in drug discovery and development activities to drive the market - BioSpace

Introduction

Given the multi-lineage differentiation abilities of mesenchymal stem cells (MSCs) isolated from different tissues and organs, MSCs have been widely used in various medical fields, particularly regenerative medicine.13 The representative sources of MSCs are bone marrow, adipose, periodontal, muscle, and umbilical cord blood.410 Interestingly, slight differences have been reported in the characteristics of MSCs depending on the different sources, including their population in source tissues, immunosuppressive activities, proliferation, and resistance to cellular aging.11 Bone marrow-derived MSCs (BM-MSCs) are the most intensively studied and show clinically promising results for cartilage and bone regeneration.11 However, the isolation procedures for BM-MSCs are complicated because bone marrow contains a relatively small fraction of MSCs (0.0010.01% of the cells in bone marrow).12 Furthermore, bone marrow aspiration to harvest MSCs in human bones is a painful procedure and the slower proliferation rate of BM-MSCs is a clinical limitation.13 In comparison with BM-MSCs, adipose-derived MSCs (AD-MSCs) are relatively easy to collect and can produce up to 500 times the cell population of BM-MSCs.14 AD-MSCs showed a greater ability to regenerate damaged cartilage and bone tissues with increased immunosuppressive ability.14,15 Umbilical cord blood-derived MSCs (UC-MSCs) proliferate faster than BM-MSCs and are resistant to significant cellular aging.11

MSCs have been investigated and gained worldwide attention as potential therapeutic candidates for incurable diseases such as arthritis, spinal cord injury, and cardiac disease.3,1623 In particular, the inherent tropism of MSCs to inflammatory sites has been thoroughly studied.24 This inherent tropism, also known as homing ability, originates from the recognition of various chemokine sources in inflamed tissues, where profiled chemokines are continuously secreted and the MSCs migrate to the chemokines in a concentration-dependent manner.24 Rheumatoid arthritis (RA) is a representative inflammatory disease that primarily causes inflammation in the joints, and this long-term autoimmune disorder causes worsening pain and stiffness following rest. RA affects approximately 24.5 million people as of 2015, but only symptomatic treatments such as pain medications, steroids, and nonsteroidal anti-inflammatory drugs (NSAIDs), or slow-acting drugs that inhibit the rapid progression of RA, such as disease-modifying antirheumatic drugs (DMARDs) are currently available. However, RA drugs have adverse side effects, including hepatitis, osteoporosis, skeletal fracture, steroid-induced arthroplasty, Cushings syndrome, gastrointestinal (GI) intolerance, and bleeding.2527 Thus, MSCs are rapidly emerging as the next generation of arthritis treatment because they not only recognize and migrate toward chemokines secreted in the inflamed joints but also regulate inflammatory progress and repair damaged cells.28

However, MSCs are associated with many challenges that need to be overcome before they can be used in clinical settings.2931 One of the main challenges is the selective accumulation of systemically administered MSCs in the lungs and liver when they are administered intravenously, leading to insufficient concentrations of MSCs in the target tissues.32,33 In addition, most of the administered MSCs are typically initially captured by macrophages in the lungs, liver, and spleen.3234 Importantly, the viability and migration ability of MSCs injected in vivo differed from results previously reported as favorable therapeutic effects and migration efficiency in vitro.35

To improve the delivery of MSCs, researchers have focused on chemokines, which are responsible for MSCs ability to move.36 The chemokine receptors are the key proteins on MSCs that recognize chemokines, and genetic engineering of MSCs to overexpress the chemokine receptor can improve the homing ability, thus enhancing their therapeutic efficacy.37 Genetic engineering is a convenient tool for modifying native or non-native genes, and several technologies for genetic engineering exist, including genome editing, gene knockdown, and replacement with various vectors.38,39 However, safety issues that prevent clinical use persist, for example, genome integration, off-target effects, and induction of immune response.40 In this regard, MSC mimicking nanoencapsulations can be an alternative strategy for maintaining the homing ability of MSCs and overcoming the current safety issues.4143 Nanoencapsulation involves entrapping the core nanoparticles of solids or liquids within nanometer-sized capsules of secondary materials.44

MSC mimicking nanoencapsulation uses the MSC membrane fraction as the capsule and targeting molecules, that is chemokine receptors, with several types of nanoparticles, as the core.45,46 MSC mimicking nanoencapsulation consists of MSC membrane-coated nanoparticles, MSC-derived artificial ectosomes, and MSC membrane-fused liposomes. Nano drug delivery is an emerging field that has attracted significant interest due to its unique characteristics and paved the way for several unique applications that might solve many problems in medicine. In particular, the nanoscale size of nanoparticles (NPs) enhances cellular uptake and can optimize intracellular pathways due to their intrinsic physicochemical properties, and can therefore increase drug delivery to target tissues.47,48 However, the inherent targeting ability resulting from the physicochemical properties of NPs is not enough to target specific tissues or damaged tissues, and additional studies on additional ligands that can bind to surface receptors on target cells or tissues have been performed to improve the targeting ability of NPs.49 Likewise, nanoencapsulation with cell membranes with targeting molecules and encapsulation of the core NPs with cell membranes confer the targeting ability of the source cell to the NPs.50,51 Thus, MSC mimicking nanoencapsulation can mimic the superior targeting ability of MSCs and confer the advantages of each core NP. In addition, MSC mimicking nanoencapsulations have improved circulation time and camouflaging from phagocytes.52

This review discusses the mechanism of MSC migration to inflammatory sites, addresses the potential strategy for improving the tropism of MSCs using genetic engineering, and discusses the promising therapeutic agent, MSC mimicking nanoencapsulations.

The MSC migration mechanism can be exploited for diverse clinical applications.53 The MSC migration mechanism can be divided into five stages: rolling by selectin, activation of MSCs by chemokines, stopping cell rolling by integrin, transcellular migration, and migration to the damaged site (Figure 1).54,55 Chemokines are secreted naturally by various cells such as tumor cells, stromal cells, and inflammatory cells, maintaining high chemokine concentrations in target cells at the target tissue and inducing signal cascades.5658 Likewise, MSCs express a variety of chemokine receptors, allowing them to migrate and be used as new targeting vectors.5961 MSC migration accelerates depending on the concentration of chemokines, which are the most important factors in the stem cell homing mechanism.62,63 Chemokines consist of various cytokine subfamilies that are closely associated with the migration of immune cells. Chemokines are divided into four classes based on the locations of the two cysteine (C) residues: CC-chemokines, CXC-chemokine, C-chemokine, and CX3 Chemokine.64,65 Each chemokine binds to various MSC receptors and the binding induces a chemokine signaling cascade (Table 1).56,66

Table 1 Chemokine and Chemokine Receptors for Different Chemokine Families

Figure 1 Representation of stem cell homing mechanism.

The mechanisms underlying MSC and leukocyte migration are similar in terms of their migratory dynamics.55 P-selectin glycoprotein ligand-1 (PSGL-1) and E-selectin ligand-1 (ESL-1) are major proteins involved in leukocyte migration that interact with P-selectin and E-selectin present in vascular endothelial cells. However, these promoters are not present in MSCs (Figure 2).53,67

Figure 2 Differences in adhesion protein molecules between leukocytes and mesenchymal stem cells during rolling stages and rolling arrest stage of MSC. (A) The rolling stage of leukocytes starts with adhesion to endothelium with ESL-1 and PSGL-1 on leukocytes. (B) The rolling stage of MSC starts with the adhesion to endothelium with Galectin-1 and CD24 on MSC, and the rolling arrest stage was caused by chemokines that were encountered in the rolling stage and VLA-4 with a high affinity for VACM present in endothelial cells.

Abbreviations: ESL-1, E-selectin ligand-1; PSGL-1, P-selectin glycoprotein ligand-1 VLA-4, very late antigen-4; VCAM, vascular cell adhesion molecule-1.

The initial rolling is facilitated by selectins expressed on the surface of endothelial cells. Various glycoproteins on the surface of MSCs can bind to the selectins and continue the rolling process.68 However, the mechanism of binding of the glycoprotein on MSCs to the selectins is still unclear.69,70 P-selectins and E-selectins, major cell-cell adhesion molecules expressed by endothelial cells, adhere to migrated cells adjacent to endothelial cells and can trigger the rolling process.71 For leukocyte migration, P-selectin glycoprotein ligand-1 (PSGL-1) and E-selectin ligand-1 (ESL-1) expressed on the membranes of leukocytes interact with P-selectins and E-selectins on the endothelial cells, initiating the process.72,73 As already mentioned, MSCs express neither PSGL-1 nor ESL-1. Instead, they express galectin-1 and CD24 on their surfaces, and these bind to E-selectin or P-selectin (Figure 2).7476

In the migratory activation step, MSC receptors are activated in response to inflammatory cytokines, including CXCL12, CXCL8, CXCL4, CCL2, and CCL7.77 The corresponding activation of chemokine receptors of MSCs in response to inflammatory cytokines results in an accumulation of MSCs.58,78 For example, inflamed tissues release inflammatory cytokines,79 and specifically, fibroblasts release CXCL12, which further induces the accumulation of MSCs through ligandreceptor interaction after exposure to hypoxia and cytokine-rich environments in the rat model of inflammation.7982 Previous studies have reported that overexpressing CXCR4, which is a receptor to recognize CXCL12, in MSCs improves the homing ability of MSCs toward inflamed sites.83,84 In short, cytokines are significantly involved in the homing mechanism of MSCs.53

The rolling arrest stage is facilitated by integrin 41 (VLA-4) on MSC.85 VLA-4 is expressed by MSCs which are first activated by CXCL-12 and TNF- chemokines, and activated VLA-4 binds to VCAM-1 expressed on endothelial cells to stop the rotational movement (Figure 2).86,87

Karp et al categorized the migration of MSCs as either systemic homing or non-systemic homing. Systemic homing refers to the process of migration through blood vessels and then across the vascular endothelium near the inflamed site.67,88 The process of migration after passing through the vessels or local injection is called non-systemic homing. In non-systemic migration, stem cells migrate through a chemokine concentration gradient (Figure 3).89 MSCs secrete matrix metalloproteinases (MMPs) during migration. The mechanism underlying MSC migration is currently undefined but MSC migration can be advanced by remodeling the matrix through the secretion of various enzymes.9093 The migration of MSCs to the damaged area is induced by chemokines released from the injured site, such as IL-8, TNF-, insulin-like growth factor (IGF-1), and platelet-derived growth factors (PDGF).9496 MSCs migrate toward the damaged area following a chemokine concentration gradient.87

Figure 3 Differences between systemic and non-systemic homing mechanisms. Both systemic and non-systemic homing to the extracellular matrix and stem cells to their destination, MSCs secrete MMPs and remodel the extracellular matrix.

Abbreviation: MMP, matrix metalloproteinase.

RA is a chronic inflammatory autoimmune disease characterized by distinct painful stiff joints and movement disorders.97 RA affects approximately 1% of the worlds population.98 RA is primarily induced by macrophages, which are involved in the innate immune response and are also involved in adaptive immune responses, together with B cells and T cells.99 Inflammatory diseases are caused by high levels of inflammatory cytokines and a hypoxic low-pH environment in the joints.100,101 Fibroblast-like synoviocytes (FLSs) and accumulated macrophages and neutrophils in the synovium of inflamed joints also express various chemokines.102,103 Chemokines from inflammatory reactions can induce migration of white blood cells and stem cells, which are involved in angiogenesis around joints.101,104,105 More than 50 chemokines are present in the rheumatoid synovial membrane (Table 2). Of the chemokines in the synovium, CXCL12, MIP1-a, CXCL8, and PDGF are the main ones that attract MSCs.106 In the RA environment, CXCL12, a ligand for CXCR4 on MSCs, had 10.71 times higher levels of chemokines than in the normal synovial cell environment. MIP-1a, a chemokine that gathers inflammatory cells, is a ligand for CCR1, which is normally expressed on MSC.107,108 CXCL8 is a ligand for CXCR1 and CXCR2 on MSCs and induces the migration of neutrophils and macrophages, leading to ROS in synovial cells.59 PDGF is a regulatory peptide that is upregulated in the synovial tissue of RA patients.109 PDGF induces greater MSC migration than CXCL12.110 Importantly, stem cells not only have the homing ability to inflamed joints but also have potential as cell therapy with the anti-apoptotic, anti-catabolic, and anti-fibrotic effect of MSC.111 In preclinical trials, MSC treatment has been extensively investigated in collagen-induced arthritis (CIA), a common autoimmune animal model used to study RA. In the RA model, MSCs downregulated inflammatory cytokines such as IFN-, TNF-, IL-4, IL-12, and IL1, and antibodies against collagen, while anti-inflammatory cytokines, such as tumor necrosis factor-inducible gene 6 protein (TSG-6), prostaglandin E2 (PGE2), transforming growth factor-beta (TGF-), IL-10, and IL-6, were upregulated.112116

Table 2 Rheumatoid Arthritis (RA) Chemokines Present in the Pathological Environment and Chemokine Receptors Present in Mesenchymal Stem Cells

Genetic engineering can improve the therapeutic potential of MSCs, including long-term survival, angiogenesis, differentiation into specific lineages, anti- and pro-inflammatory activity, and migratory properties (Figure 4).117,118 Although MSCs already have an intrinsic homing ability, the targeting ability of MSCs and their derivatives, such as membrane vesicles, which are utilized to produce MSC mimicking nanoencapsulation, can be enhanced.118 The therapeutic potential of MSCs can be magnified by reprogramming MSCs via upregulation or downregulation of their native genes, resulting in controlled production of the target protein, or by introducing foreign genes that enable MSCs to express native or non-native products, for example, non-native soluble tumor necrosis factor (TNF) receptor 2 can inhibit TNF-alpha signaling in RA therapies.28

Figure 4 Genetic engineering of mesenchymal stem cells to enhance therapeutic efficacy.

Abbreviations: Sfrp2, secreted frizzled-related protein 2; IGF1, insulin-like growth factor 1; IL-2, interleukin-2; IL-12, interleukin-12; IFN-, interferon-beta; CX3CL1, C-X3-C motif chemokine ligand 1; VEGF, vascular endothelial growth factor; HGF, human growth factor; FGF, fibroblast growth factor; IL-10, interleukin-10; IL-4, interleukin-4; IL18BP, interleukin-18-binding protein; IFN-, interferon-alpha; SDF1, stromal cell-derived factor 1; CXCR4, C-X-C motif chemokine receptor 4; CCR1, C-C motif chemokine receptor 1; BMP2, bone morphogenetic protein 2; mHCN2, mouse hyperpolarization-activated cyclic nucleotide-gated.

MSCs can be genetically engineered using different techniques, including by introducing particular genes into the nucleus of MSCs or editing the genome of MSCs (Figure 5).119 Foreign genes can be transferred into MSCs using liposomes (chemical method), electroporation (physical method), or viral delivery (biological method). Cationic liposomes, also known as lipoplexes, can stably compact negatively charged nucleic acids, leading to the formation of nanomeric vesicular structure.120 Cationic liposomes are commonly produced with a combination of a cationic lipid such as DOTAP, DOTMA, DOGS, DOSPA, and neutral lipids, such as DOPE and cholesterol.121 These liposomes are stable enough to protect their bound nucleic acids from degradation and are competent to enter cells via endocytosis.120 Electroporation briefly creates holes in the cell membrane using an electric field of 1020 kV/cm, and the holes are then rapidly closed by the cells membrane repair mechanism.122 Even though the electric shock induces irreversible cell damage and non-specific transport into the cytoplasm leads to cell death, electroporation ensures successful gene delivery regardless of the target cell or organism. Viral vectors, which are derived from adenovirus, adeno-associated virus (AAV), or lentivirus (LV), have been used to introduce specific genes into MSCs. Recombinant lentiviral vectors are the most widely used systems due to their high tropism to dividing and non-dividing cells, transduction efficiency, and stable expression of transgenes in MSCs, but the random genome integration of transgenes can be an obstacle in clinical applications.123 Adenovirus and AAV systems are appropriate alternative strategies because currently available strains do not have broad genome integration and a strong immune response, unlike LV, thus increasing success and safety in clinical trials.124 As a representative, the Oxford-AstraZeneca COVID-19 vaccine, which has been authorized in 71 countries as a vaccine for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which spread globally and led to the current pandemic, transfers the spike protein gene using an adenovirus-based viral vector.125 Furthermore, there are two AAV-based gene therapies: Luxturna for rare inherited retinal dystrophy and Zolgensma for spinal muscular atrophy.126

Figure 5 Genetic engineering techniques used in the production of bioengineered mesenchymal stem cells.

Clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 were recently used for genome editing and modification because of their simpler design and higher efficiency for genome editing, however, there are safety issues such as off-target effects that induce mutations at sites other than the intended target site.127 The foreign gene is then commonly transferred into non-integrating forms such as plasmid DNA and messenger RNA (mRNA).128

The gene expression machinery can also be manipulated at the cytoplasmic level through RNA interference (RNAi) technology, inhibition of gene expression, or translation using neutralizing targeted mRNA molecules with sequence-specific small RNA molecules such as small interfering RNA (siRNA) or microRNA (miRNA).129 These small RNAs can form enzyme complexes that degrade mRNA molecules and thus decrease their activity by inhibiting translation. Moreover, the pre-transcriptional silencing mechanism of RNAi can induce DNA methylation at genomic positions complementary to siRNA or miRNA with enzyme complexes.

CXC chemokine receptor 4 (CXCR4) is one of the most potent chemokine receptors that is genetically engineered to enhance the migratory properties of MSCs.130 CXCR4 is a chemokine receptor specific for stromal-derived factor-1 (SDF-1), also known as CXC motif chemokine 12 (CXCL12), which is produced by damaged tissues, such as the area of inflammatory bone destruction.131 Several studies on engineering MSCs to increase the expression of the CXCR4 gene have reported a higher density of the CXCR4 receptor on their outer cell membrane and effectively increased the migration of MSCs toward SDF-1.83,132,133 CXC chemokine receptor 7 (CXCR7) also had a high affinity for SDF-1, thus the SDF-1/CXCR7 signaling axis was used to engineer the MSCs.134 CXCR7-overexpressing MSCs in a cerebral ischemia-reperfusion rat hippocampus model promoted migration based on an SDF-1 gradient, cooperating with the SDF-1/CXCR4 signaling axis (Figure 6).37

Figure 6 Engineered mesenchymal stem cells with enhanced migratory abilities.

Abbreviations: CXCR4, C-X-C motif chemokine receptor 4; CXCR7, C-X-C motif chemokine receptor 7; SDF1, stromal cell-derived factor 1; CXCR1, C-X-C motif chemokine receptor 1; IL-8, interleukin-8; Aqp1, aquaporin 1; FAK, focal adhesion kinase.

CXC chemokine receptor 1 (CXCR1) enhances MSC migratory properties.59 CXCR1 is a receptor for IL-8, which is the primary cytokine involved in the recruitment of neutrophils to the site of damage or infection.135 In particular, the IL-8/CXCR1 axis is a key factor for the migration of MSCs toward human glioma cell lines, such as U-87 MG, LN18, U138, and U251, and CXCR1-overexpressing MSCs showed a superior capacity to migrate toward glioma cells and tumors in mice bearing intracranial human gliomas.136

The migratory properties of MSCs were also controlled via aquaporin-1 (Aqp1), which is a water channel molecule that transports water across the cell membrane and regulates endothelial cell migration.137 Aqp1-overexpressing MSCs showed enhanced migration to fracture gap of a rat fracture model with upregulated focal adhesion kinase (FAK) and -catenin, which are important regulators of cell migration.138

Nur77, also known as nerve growth factor IB or NR4A1, and nuclear receptor-related 1 (Nurr1), can play a role in improving the migratory capabilities of MSCs.139,140 The migrating MSCs expressed higher levels of Nur77 and Nurr1 than the non-migrating MSCs, and overexpression of these two nuclear receptors functioning as transcription factors enhanced the migration of MSCs toward SDF-1. The migration of cells is closely related to the cell cycle, and normally, cells in the late S or G2/M phase do not migrate.141 The overexpression of Nur77 and Nurr1 increased the proportion of MSCs in the G0/G1-phase similar to the results of migrating MSCs had more cells in the G1-phase.

MSC mimicking nanoencapsulations are nanoparticles combined with MSC membrane vesicles and these NPs have the greatest advantages as drug delivery systems due to the sustained homing ability of MSCs as well as the advantages of NPs. Particles sized 10150 nm have great advantages in drug delivery systems because they can pass more freely through the cell membrane by the interaction with biomolecules, such as clathrin and caveolin, to facilitate uptake across the cell membrane compared with micron-sized materials.142,143 Various materials have been used to formulate NPs, including silica, polymers, metals, and lipids.144,145 NPs have an inherent ability, called passive targeting, to accumulate at specific sites based on their physicochemical properties such as size, surface charge, surface hydrophilicity, and geometry.146148 However, physicochemical properties are not enough to target specific tissues or damaged tissues, and thus active targeting is a clinically approved strategy involving the addition of ligands that can bind to surface receptors on target cells or tissues.149,150 MSC mimicking nanoencapsulation uses natural or genetically engineered MSC membranes to coat synthetic NPs, producing artificial ectosomes and fusing them with liposomes to increase their targeting ability (Figure 7).151 Especially, MSCs have been studied for targeting inflammation and regenerative drugs, and the mechanism and efficacy of migration toward inflamed tissues have been actively investigated.152 MSC mimicking nanoencapsulation can mimic the well-known migration ability of MSCs and can be equally utilized without safety issues from the direct application of using MSCs. Furthermore, cell membrane encapsulations have a wide range of functions, including prolonged blood circulation time and increased active targeting efficacy from the source cells.153,154 MSC mimicking encapsulations enter recipient cells using multiple pathways.155 MSC mimicking encapsulations can fuse directly with the plasma membrane and can also be taken up through phagocytosis, micropinocytosis, and endocytosis mediated by caveolin or clathrin.156 MSC mimicking encapsulations can be internalized in a highly cell type-specific manner that depends on the recognition of membrane surface molecules by the cell or tissue.157 For example, endothelial colony-forming cell (ECFC)-derived exosomes were shown CXCR4/SDF-1 interaction and enhanced delivery toward the ischemic kidney, and Tspan8-alpha4 complex on lymph node stroma derived extracellular vesicles induced selective uptake by endothelial cells or pancreatic cells with CD54, serving as a major ligand.158,159 Therefore, different source cells may contain protein signals that serve as ligands for other cells, and these receptorligand interactions maximized targeted delivery of NPs.160 This natural mechanism inspired the application of MSC membranes to confer active targeting to NPs.

Figure 7 Mesenchymal stem cell mimicking nanoencapsulation.

Cell membrane-coated NPs (CMCNPs) are biomimetic strategies developed to mimic the properties of cell membranes derived from natural cells such as erythrocytes, white blood cells, cancer cells, stem cells, platelets, or bacterial cells with an NP core.161 Core NPs made of polymer, silica, and metal have been evaluated in attempts to overcome the limitations of conventional drug delivery systems but there are also issues of toxicity and reduced biocompatibility associated with the surface properties of NPs.162,163 Therefore, only a small number of NPs have been approved for medical application by the FDA.164 Coating with cell membrane can enhance the biocompatibility of NPs by improving immune evasion, enhancing circulation time, reducing RES clearance, preventing serum protein adsorption by mimicking cell glycocalyx, which are chemical determinants of self at the surfaces of cells.151,165 Furthermore, the migratory properties of MSCs can also be transferred to NPs by coating them with the cell membrane.45 Coating NPs with MSC membranes not only enhances biocompatibility but also maximizes the therapeutic effect of NPs by mimicking the targeting ability of MSCs.166 Cell membrane-coated NPs are prepared in three steps: extraction of cell membrane vesicles from the source cells, synthesis of the core NPs, and fusion of the membrane vesicles and core NPs to produce cell membrane-coated NPs (Figure 8).167 Cell membrane vesicles, including extracellular vesicles (EVs), can be harvested through cell lysis, mechanical disruption, and centrifugation to isolate, purify the cell membrane vesicles, and remove intracellular components.168 All the processes must be conducted under cold conditions, with protease inhibitors to minimize the denaturation of integral membrane proteins. Cell lysis, which is classically performed using mechanical lysis, including homogenization, sonication, or extrusion followed by differential velocity centrifugation, is necessary to remove intracellular components. Cytochalasin B (CB), a drug that affects cytoskeletonmembrane interactions, induces secretion of membrane vesicles from source cells and has been used to extract the cell membrane.169 The membrane functions of the source cells are preserved in CB-induced vesicles, forming biologically active surface receptors and ion pumps.170 Furthermore, CB-induced vesicles can encapsulate drugs and NPs successfully, and the vesicles can be harvested by centrifugation without a purification step to remove nuclei and cytoplasm.171 Clinically translatable membrane vesicles require scalable production of high volumes of homogeneous vesicles within a short period. Although mechanical methods (eg, shear stress, ultrasonication, or extrusion) are utilized, CB-induced vesicles have shown potential for generating membrane encapsulation for nano-vectors.168 The advantages of CB-induced vesicles versus other methods are compared in Table 3.

Table 3 Comparison of Membrane Vesicle Production Methods

Figure 8 MSC membrane-coated nanoparticles.

Abbreviations: EVs, extracellular vesicles; NPs, nanoparticles.

After extracting cell membrane vesicles, synthesized core NPs are coated with cell membranes, including surface proteins.172 Polymer NPs and inorganic NPs are adopted as materials for the core NPs of CMCNPs, and generally, polylactic-co-glycolic acid (PLGA), polylactic acid (PLA), chitosan, and gelatin are used. PLGA has been approved by FDA is the most common polymer of NPs.173 Biodegradable polymer NPs have gained considerable attention in nanomedicine due to their biocompatibility, nontoxic properties, and the ability to modify their surface as a drug carrier.174 Inorganic NPs are composed of gold, iron, copper, and silicon, which have hydrophilic, biocompatible, and highly stable properties compared with organic materials.175 Furthermore, some photosensitive inorganic NPs have the potential for use in photothermal therapy (PTT) and photodynamic therapy (PDT).176 The fusion of cell membrane vesicles and core NPs is primarily achieved via extrusion or sonication.165 Cell membrane coating of NPs using mechanical extrusion is based on a different-sized porous membrane where core NPs and vesicles are forced to generate vesicle-particle fusion.177 Ultrasonic waves are applied to induce the fusion of vesicles and NPs. However, ultrasonic frequencies need to be optimized to improve fusion efficiency and minimize drug loss and protein degradation.178

CMCNPs have extensively employed to target and treat cancer using the membranes obtained from red blood cell (RBC), platelet and cancer cell.165 In addition, membrane from MSC also utilized to target tumor and ischemia with various types of core NPs, such as MSC membrane coated PLGA NPs targeting liver tumors, MSC membrane coated gelatin nanogels targeting HeLa cell, MSC membrane coated silica NPs targeting HeLa cell, MSC membrane coated PLGA NPs targeting hindlimb ischemia, and MSC membrane coated iron oxide NPs for targeting the ischemic brain.179183 However, there are few studies on CMCNPs using stem cells for the treatment of arthritis. Increased targeting ability to arthritis was introduced using MSC-derived EVs and NPs.184,185 MSC membrane-coated NPs are proming strategy for clearing raised concerns from direct use of MSC (with or without NPs) in terms of toxicity, reduced biocompatibility, and poor targeting ability of NPs for the treatment of arthritis.

Exosomes are natural NPs that range in size from 40 nm to 120 nm and are derived from the multivesicular body (MVB), which is an endosome defined by intraluminal vesicles (ILVs) that bud inward into the endosomal lumen, fuse with the cell surface, and are then released as exosomes.186 Because of their ability to express receptors on their surfaces, MSC-derived exosomes are also considered potential candidates for targeting.187 Exosomes are commonly referred to as intracellular communication molecules that transfer various compounds through physiological mechanisms such as immune response, neural communication, and antigen presentation in diseases such as cancer, cardiovascular disease, diabetes, and inflammation.188

However, there are several limitations to the application of exosomes as targeted therapeutic carriers. First, the limited reproducibility of exosomes is a major challenge. In this field, the standardized techniques for isolation and purification of exosomes are lacking, and conventional methods containing multi-step ultracentrifugation often lead to contamination of other types of EVs. Furthermore, exosomes extracted from cell cultures can vary and display inconsistent properties even when the same type of donor cells were used.189 Second, precise characterization studies of exosomes are needed. Unknown properties of exosomes can hinder therapeutic efficiencies, for example, when using exosomes as cancer therapeutics, the use of cancer cell-derived exosomes should be avoided because cancer cell-derived exosomes may contain oncogenic factors that may contribute to cancer progression.190 Finally, cost-effective methods for the large-scale production of exosomes are needed for clinical application. The yield of exosomes is much lower than EVs. Depending on the exosome secretion capacity of donor cells, the yield of exosomes is restricted, and large-scale cell culture technology for the production of exosomes is high difficulty and costly and isolation of exosomes is the time-consuming and low-efficient method.156

Ectosome is an EV generated by outward budding from the plasma membrane followed by pinching off and release to the extracellular parts. Recently, artificially produced ectosome utilized as an alternative to exosomes in targeted therapeutics due to stable productivity regardless of cell type compared with conventional exosome. Artificial ectosomes, containing modified cargo and targeting molecules have recently been introduced for specific purposes (Figure 9).191,192 Artificial ectosomes are typically prepared by breaking bigger cells or cell membrane fractions into smaller ectosomes, similar size to natural exosomes, containing modified cargo such as RNA molecules, which control specific genes, and chemical drugs such as anticancer drugs.193 Naturally secreted exosomes in conditioned media from modified source cells can be harvested by differential ultracentrifugation, density gradients, precipitation, filtration, and size exclusion chromatography for exosome separation.194 Even though there are several commercial kits for isolating exosomes simply and easily, challenges in compliant scalable production on a large scale, including purity, homogeneity, and reproducibility, have made it difficult to use naturally secreted exosomes in clinical settings.195 Therefore, artificially produced ectosomes are appropriate for use in clinical applications, with novel production methods that can meet clinical production criteria. Production of artificially produced ectosomes begins by breaking the cell membrane fraction of cultured cells and then using them to produce cell membrane vesicles to form ectosomes. As mentioned above, cell membrane vesicles are extracted from source cells in several ways, and cell membrane vesicles are extracted through polycarbonate membrane filters to reduce the mean size to a size similar to that of natural exosomes.196 Furthermore, specific microfluidic devices mounted on microblades (fabricated in silicon nitride) enable direct slicing of living cells as they flow through the hydrophilic microchannels of the device.197 The sliced cell fraction reassembles and forms ectosomes. There are several strategies for loading exogenous therapeutic cargos such as drugs, DNA, RNA, lipids, metabolites, and proteins, into exosomes or artificial ectosomes in vitro: electroporation, incubation for passive loading of cargo or active loading with membrane permeabilizer, freeze and thaw cycles, sonication, and extrusion.198 In addition, protein or RNA molecules can be loaded by co-expressing them in source cells via bio-engineering, and proteins designed to interact with the protein inside the cell membrane can be loaded actively into exosomes or artificial ectosomes.157 Targeting molecules at the surface of exosomes or artificial ectosomes can also be engineered in a manner similar to the genetic engineering of MSCs.

Figure 9 Mesenchymal stem cell-derived exosomes and artificial ectosomes. (A) Wound healing effect of MSC-derived exosomes and artificial ectosomes,231 (B) treatment of organ injuries by MSC-derived exosomes and artificial ectosomes,42,232234 (C) anti-cancer activity of MSC-derived exosomes and artificial ectosomes.200,202,235

Most of the exosomes derived from MSCs for drug delivery have employed miRNAs or siRNAs, inhibiting translation of specific mRNA, with anticancer activity, for example, miR-146b, miR-122, and miR-379, which are used for cancer targeting by membrane surface molecules on MSC-derived exosomes.199201 Drugs such as doxorubicin, paclitaxel, and curcumin were also loaded into MSC-derived exosomes to target cancer.202204 However, artificial ectosomes derived from MSCs as arthritis therapeutics remains largely unexplored area, while EVs, mixtures of natural ectosomes and exosomes, derived from MSCs have studied in the treatment of arthritis.184 Artificial ectosomes with intrinsic tropism from MSCs plus additional targeting ability with engineering increase the chances of ectosomes reaching target tissues with ligandreceptor interactions before being taken up by macrophages.205 Eventually, this will decrease off-target binding and side effects, leading to lower therapeutic dosages while maintaining therapeutic efficacy.206,207

Liposomes are spherical vesicles that are artificially synthesized through the hydration of dry phospholipids.208 The clinically available liposome is a lipid bilayer surrounding a hollow core with a diameter of 50150 nm. Therapeutic molecules, such as anticancer drugs (doxorubicin and daunorubicin citrate) or nucleic acids, can be loaded into this hollow core for delivery.209 Due to their amphipathic nature, liposomes can load both hydrophilic (polar) molecules in an aqueous interior and hydrophobic (nonpolar) molecules in the lipid membrane. They are well-established biomedical applications and are the most common nanostructures used in advanced drug delivery.210 Furthermore, liposomes have several advantages, including versatile structure, biocompatibility, low toxicity, non-immunogenicity, biodegradability, and synergy with drugs: targeted drug delivery, reduction of the toxic effect of drugs, protection against drug degradation, and enhanced circulation half-life.211 Moreover, surfaces can be modified by either coating them with a functionalized polymer or PEG chains to improve targeted delivery and increase their circulation time in biological systems.212 Liposomes have been investigated for use in a wide variety of therapeutic applications, including cancer diagnostics and therapy, vaccines, brain-targeted drug delivery, and anti-microbial therapy. A new approach was recently proposed for providing targeting features to liposomes by fusing them with cell membrane vesicles, generating molecules called membrane-fused liposomes (Figure 10).213 Cell membrane vesicles retain the surface membrane molecules from source cells, which are responsible for efficient tissue targeting and cellular uptake by target cells.214 However, the immunogenicity of cell membrane vesicles leads to their rapid clearance by macrophages in the body and their low drug loading efficiencies present challenges for their use as drug delivery systems.156 However, membrane-fused liposomes have advantages of stability, long half-life in circulation, and low immunogenicity due to the liposome, and the targeting feature of cell membrane vesicles is completely transferred to the liposome.215 Furthermore, the encapsulation efficiencies of doxorubicin were similar when liposomes and membrane-fused liposomes were used, indicating that the relatively high drug encapsulation capacity of liposomes was maintained during the fusion process.216 Combining membrane-fused liposomes with macrophage-derived membrane vesicles showed differential targeting and cytotoxicity against normal and cancerous cells.217 Although only a few studies have been conducted, these results corroborate that membrane-fused liposomes are a potentially promising future drug delivery system with increased targeting ability. MSCs show intrinsic tropism toward arthritis, and further engineering and modification to enhance their targeting ability make them attractive candidates for the development of drug delivery systems. Fusing MSC exosomes with liposomes, taking advantage of both membrane vesicles and liposomes, is a promising technique for future drug delivery systems.

Figure 10 Mesenchymal stem cell membrane-fused liposomes.

MSCs have great potential as targeted therapies due to their greater ability to home to targeted pathophysiological sites. The intrinsic ability to home to wounds or to the tumor microenvironment secreting inflammatory mediators make MSCs and their derivatives targeting strategies for cancer and inflammatory disease.218,219 Contrary to the well-known homing mechanisms of various blood cells, it is still not clear how homing occurs in MSCs. So far, the mechanism of MSC tethering, which connects long, thin cell membrane cylinders called tethers to the adherent area for migration, has not been clarified. Recent studies have shown that galectin-1, VCAM-1, and ICAM are associated with MSC tethering,53,220 but more research is needed to accurately elucidate the tethering mechanism of MSCs. MSC chemotaxis is well defined and there is strong evidence relating it to the homing ability of MSCs.53 Chemotaxis involves recognizing chemokines through chemokine receptors on MSCs and migrating to chemokines in a gradient-dependent manner.221 RA, a representative inflammatory disease, is associated with well-profiled chemokines such as CXCR1, CXCR4, and CXCR7, which are recognized by chemokine receptors on MSCs. In addition, damaged joints in RA continuously secrete cytokines until they are treated, giving MSCs an advantage as future therapeutic agents for RA.222 However, there are several obstacles to utilizing MSCs as RA therapeutics. In clinical settings, the functional capability of MSCs is significantly affected by the health status of the donor patient.223 MSC yield is significantly reduced in patients undergoing steroid-based treatment and the quality of MSCs is dependent on the donors age and environment.35 In addition, when MSCs are used clinically, cryopreservation and defrosting are necessary, but these procedures shorten the life span of MSCs.224 Therefore, NPs mimicking MSCs are an alternative strategy for overcoming the limitations of MSCs. Additionally, further engineering and modification of MSCs can enhance the therapeutic effect by changing the targeting molecules and loaded drugs. In particular, upregulation of receptors associated with chemotaxis through genetic engineering can confer the additional ability of MSCs to home to specific sites, while the increase in engraftment maximizes the therapeutic effect of MSCs.36,225

Furthermore, there are several methods that can be used to exploit the targeting ability of MSCs as drug delivery systems. MSCs mimicking nanoencapsulation, which consists of MSC membrane-coated NPs, MSC-derived artificial ectosomes, and MSC membrane-fused liposomes, can mimic the targeting ability of MSCs while retaining the advantages of NPs. MSC-membrane-coated NPs are synthesized using inorganic or polymer NPs and membranes from MSCs to coat inner nanosized structures. Because they mimic the biological characteristics of MSC membranes, MSC-membrane-coated NPs can not only escape from immune surveillance but also effectively improve targeting ability, with combined functions of the unique properties of core NPs and MSC membranes.226 Exosomes are also an appropriate candidate for use in MSC membranes, utilizing these targeting abilities. However, natural exosomes lack reproducibility and stable productivity, thus artificial ectosomes with targeting ability produced via synthetic routes can increase the local concentration of ectosomes at the targeted site, thereby reducing toxicity and side effects and maximizing therapeutic efficacy.156 MSC membrane-fused liposomes, a novel system, can also transfer the targeting molecules on the surface of MSCs to liposomes; thus, the advantages of liposomes are retained, but with targeting ability. With advancements in nanotechnology of drug delivery systems, the research in cell-mimicking nanoencapsulation will be very useful. Efficient drug delivery systems fundamentally improve the quality of life of patients with a low dose of medication, low side effects, and subsequent treatment of diseases.227 However, research on cell-mimicking nanoencapsulation is at an early stage, and several problems need to be addressed. To predict the nanotoxicity of artificially synthesized MSC mimicking nanoencapsulations, interactions between lipids and drugs, drug release mechanisms near the targeted site, in vivo compatibility, and immunological physiological studies must be conducted before clinical application.

This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF-2019M3A9H1103690), by the Gachon University Gil Medical Center (FRD2021-03), and by the Gachon University research fund of 2020 (GGU-202008430004).

The authors report no conflicts of interest in this work.

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Stem Cell Mimicking Nanoencapsulation for Targeting Arthrit | IJN - Dove Medical Press

Medical science is starting to license and use drugs and procedures that change the genetic code inside the bodys cells, and to correct the bad code that can give rise to conditions such as cancer and the auto-immune diseases. Since HIV is a disease that results from a virus inserting such a piece of bad code into our genes, such therapies could be used to snip out that code and effect a cure.

This was what attendees at last months International AIDS Society Conference on HIV Science (IAS 2021) heard at the workshop on curing HIV. The workshop opened with two introductory talks by Professor Hans-Peter Kiem, the chair of gene therapy at the Fred Hutchinson Cancer Research Center in Seattle in the US (the Fred Hutch) and, in a joint presentation, by the Fred Hutchs Dr Jennifer Adair and Dr Cissy Kityo of the Joint Clinical Research Centre (JCRC) in Kampala, Uganda.

The latter talk was a sign of acknowledgement that, while the prospects for genetic medicine are brighter than ever before, their expense and sophistication do not fit well with the global epidemiology of HIV, which mainly affects the worlds poorest and most disadvantaged communities. Despite this, Fred Hutch and JCRC have embarked upon a joint research programme to develop within the next few years a genetic therapy treatment for HIV that could be realistically scaled up for use in lower-income settings.

A unit of heredity, that determines a specific feature of the shape of a living organism. This genetic element is a sequence of DNA (or RNA, for viruses), located in a very specific place (locus) of a chromosome.

A type of experimental treatment in which foreign genetic material (DNA or RNA) is inserted into a person's cells to prevent or fight disease.

To eliminate a disease or a condition in an individual, or to fully restore health. A cure for HIV infection is one of the ultimate long-term goals of research today. It refers to a strategy or strategies that would eliminate HIV from a persons body, or permanently control the virus and render it unable to cause disease. A sterilising cure would completely eliminate the virus. A functional cure would suppress HIV viral load, keeping it below the level of detection without the use of ART. The virus would not be eliminated from the body but would be effectively controlled and prevented from causing any illness.

The body's mechanisms for fighting infections and eradicating dysfunctional cells.

In cell biology, a structure on the surface of a cell (or inside a cell) that selectively receives and binds to a specific substance. There are many receptors. CD4 T cells are called that way because they have a protein called CD4 on their surface. Before entering (infecting) a CD4 T cell (that will become a host cell), HIV binds to the CD4 receptor and its coreceptor.

HIV cure research pioneer Dr Paula Cannon of the University of Southern California, chairing the session, said: After several decades of effort and false starts, gene therapies now hold out promise for diseases that were previously untreatable.

Hans-Peter Kiem acknowledged the pivotal role of community advocacy in supporting cure research, noting that his project, defeatHIV, was one of the first beneficiaries of a grant from the Martin Delaney Collaboratories, named after the celebrated US treatment activist who died in 2009.

The other factor that gave impetus to HIV cure research was, of course, the announcement that someone had been cured: Timothy Ray Brown, whose HIV elimination was first announced in 2008 and who came forward publicly in 2010. He died in 2019 from the leukaemia whose treatment led to his HIV cure but by then had had 13 years of post-HIV life. He had survived long enough to talk with Adam Castillejo, the second person cured of HIV, and encourage him to come forward too.

Timothy and Adams stories showed that HIV could be cured, and with a crude form of gene therapy too: cancer patients, they were both given bone marrow transplants from donors whose T-cells lacked the gene for the CCR5 receptor, which is necessary for nearly all HIV infection.

But there have only been two cures for two reasons: firstly, bone marrow transplant is itself a very risky procedure involving deleting and replacing the entire immune system of already sick patients. In 2014 Browns doctor, Gero Hutter, reported that Timothy Ray Brown was only one of out of eight patients on whom the procedure had been tried, but that all the others had died.

Secondly, compatible bone marrow donors are hard to come by as it is, and restricting them to the 1% or so of people who lack the CCR5 receptor, all of them of northern European ancestry, means very few people could benefit from this approach. Attempting transplant with T-cells that do not lack CCR5, in the hope that replacing the immune system with cells from a person without cancer will also get rid of their HIV anyway, has produced temporary periods of undetectable HIV off therapy, but the virus has always come back.

(People like Brown and Castillejo, whose HIV infection was cured by medical intervention, need to be distinguished from people who seem to have spontaneously cured themselves, such as Loreen Willenberg: such people are of course of great interest to cure researchers, but the trick is to make it happen consistently in other people.)

Brown and Castillejos cures, as transplants, were so-called allogenic, meaning that the HIV-resistant cells came from another person. Better would be autogenic transplants, in which immune system cells are taken from a person with HIV, genetically altered in the lab dish to make them resistant to HIV, and then re-introduced. This type of procedure written about for aidsmap as long ago as 2011 by treatment advocate Matt Sharp, who underwent one.

The repertoire of gene therapies is not restricted to CCR5 deletion. Gene therapy is immensely versatile, and could be used in a number of ways.

Instead of using gene therapy to make cells resistant to HIV, it could directly repair defective genes in cells by means of cut-and-paste technology such as CRISPR/Cas9. This is already being used in trials for some genetic conditions such as cystic fibrosis and sickle-cell anaemia. Given that HIV-infected cells are also defective in the sense that they contain lengths of foreign DNA that shouldnt be there, they are amenable to the same molecular editing. Early trials have produced promising results but the challenge, as it has been in a lot of gene therapy, is to ensure that the cells containing DNA are almost entirely eliminated.

One way of doing this is not to delete the HIV DNA from infected cells but to preferentially kill off the cells themselves by creating so-called chimeric antigen receptor (CAR) T-cells. These are T-lymphocytes whose genes have been modified so that their usual receptors such as CD4 or CD8 have been replaced with receptors attuned very specifically to antigens (foreign or unusual proteins) displayed by infected cells and cancer cells. A couple of CAR cell therapies are already licensed for cancers; the problem with HIV is that the reservoir cells do not display immune-stimulating antigens on their surfaces. This means that CAR T-cells would have to be used alongside drugs such as PD-1 inhibitors that stop the cells retreating into their quiescent reservoir phase, an approach demonstrated at IAS 2021.

A couple of other approaches could be used to produce either vaccines or cures. One is to engineer B-cells so they produce broadly neutralising antibodies. A way of tweaking them to do this, called germline targeting, is covered was also discussed at IAS 2021, but if we manage to generate B-cells that can do this, we could then in theory directly edit their genes to make them do the same thing.

"Timothy Ray Brown and Adam Castillejo were both given bone marrow transplants from donors whose T-cells lacked the gene for the CCR5 receptor."

The other way is to induce cells to make viral antigens or virus-like particles that the immune system then reacts to. Scientists have been working on this technique for 20 years and it triumphed last year when the Pfizer and Moderna vaccines against the SARS-CoV-2 virus had over 90% success in suppressing symptomatic COVID-19. These vaccines are not genetic engineering in the sense of altering the genome of cells; rather, they introduce a product of the genetic activation in cells, the messenger RNA that is produced when genes are read and which is sent out into the rest of the cell to tell it to make proteins.

However because HIV is more variable and less immunogenic than SARS-CoV-2, the vaccine induced by the RNA would have to be something that looked much more like a whole virus than just the bare spike protein induced by the Pfizer and Moderna vaccines. If there was such a vaccine could be used both therapeutically as well as in prevention, by stimulating an immune reaction to activated HIV-infected cells. Moderna have announced they will now resume the HIV vaccine research they were working on when COVID-19 hit.

The problem with all these more gentle procedures is that it has proved difficult to replace all the HIV-susceptible cells with the HIV-resistant or HIV-sensitised ones: although engraftment takes place, meaning that the autologous cells are not rejected by the body and are able to establish a population for some time (in some animal experiments, replacing as much as 90% of the native immune cells), eventually the unaltered immune cells tend to win out because the introduced cells lack the deep reservoir of replenishing cells.

Kiem said that the way scientists have been trying to get round this is to only select and alter so-called haematopoeic stem cells (HSCs). These rare and long-lived cells, found in the bone marrow, are the replenishing reservoir of the immune system. They differentiate when they reproduce and give rise to all the immune cells that do different things: CD4 and CD8 T-lymphocytes, B-cells that make antibodies, macrophages that engulf pathogens, dendritic cells, monocytes, natural killer cells, and others.

Altering HSCs genetically so that they are able to fight HIV in one way or another could in theory give rise to a persistent, HIV-resistant immune system. They could in theory lie in wait and be ready to produce effector cells of various types. They would be ready when a new HIV infection comes along (if used as a vaccine) or when HIV viral rebound happens and there is detectable virus in the body (if used as part of a cure). If a person with CAR-engineered stem cells could have repeated cycles of treatment interruption, their HIV reservoir could in theory slowly be deleted.

"Gene therapies are astonishingly expensive."

As mentioned above, although genetic medicine shows enormous promise, the complexity and expense of its techniques means that at present it is unlikely to benefit most people who really need it.

Hans-Peter Kiem said that currently about 60 million people have conditions that could benefit from gene therapy. The vast majority of these either have HIV (37 million) or haemoglobinopathies blood-malformation diseases such as sickle-cell anaemia and thalassaemia that are also concentrated in the lower-income world (20 million).

Dr Jennifer Adair, one of the first researchers to have proposed collaboration on gene therapies for HIV with African institutes, said that gene therapies have already been licensed for conditions such as thalassaemia, spinal muscular atrophy, T-cell lymphoma and a form of early-onset blindness.

But they are astonishingly expensive. The worlds most expensive drug tag goes, depending on which source you read, either to Zynteglo, a genetic medicine correcting malformed beta-haemoglobin and licensed in the US for thalassaemia, or Zolgensma, a drug licensed in Europe and given to children to correct the defective gene that results in spinal muscular atrophy.

Both cost about 1.8 million for a single dose. The price is not just due to the cost of the complex engineering used to make them, but because they are used to treat rare diseases and so have a small market.

At present the technology need to engineer autogenic genetically engineered cells is, if anything, even more expensive and complex than that needed to introduce allogenic cells. It can involve in the region of ten staff and a workspace of 50 square metres per patient. Recently a so-called gene therapy in a box has been made available that can reduce the area needed to produce autogenic genetically-engineered cells from 50 to less than one square metre, and the staff need to one or two, But what is really needed is genetic engineering in a shot; a therapy similar to a vector or RNA vaccine that can be introduced as an injection and produces the genetic changes needed within the body.

Undaunted by the challenges, the US National Institutes of Health are collaborating with the Bill and Melinda Gates foundation to work on a combined programme of HIV and sickle-cell-anaemia genetic therapy (given that something that works for one could be adapted to work with the other).

And the Fred Hutchinson Center has teamed up with the Joint Clinical Research Centre in Uganda with the very ambitious goal of making a genetic therapy that would be at least ready for human testing within two years in an African setting, and that could be scaled up to be economical for Africa if successful.

Dr Cissy Kityo of JCRC in Uganda told the conference that as of 2020, there were 373 trials of gene therapy products registered, of which 35 were in phase III efficacy trials. The global budget for regenerative medicine, which includes genetic therapy and related techniques, was $19.9 billion, having jumped by 30% since the previous year. The US Food and Drug Administration projects that based on the current rate of progress and the development pipeline, they may be licensing around 100 gene-therapy products a year by 2025.

This branch of medicine is no longer exotic, she said. Now steps have to be taken to trial gene therapies in the people who needed them most, and to turn the exotic into the affordable, she added.

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Could gene therapies be used to cure more people with HIV? - aidsmap

DetailsCategory: DNA RNA and CellsPublished on Tuesday, 03 August 2021 10:03Hits: 951

Off-the-Shelf CAR T-cell Product Candidate Derived from Clonal Master iPSC Line with Novel CD19-specific 1XX CAR Integrated into TRAC Locus

Phase 1 Clinical Study will Evaluate Three Dosing Regimens of FT819 for Patients with Advanced B-cell Leukemias and Lymphomas

SAN DIEGO, CA, USA I August 02, 2021 I Fate Therapeutics, Inc. (NASDAQ: FATE), a clinical-stage biopharmaceutical company dedicated to the development of programmed cellular immunotherapies for patients with cancer, announced today that the first patient has been treated with FT819, an off-the-shelf chimeric antigen receptor (CAR) T-cell therapy targeting CD19+ malignancies. FT819 is the first-ever CAR T-cell therapy derived from a clonal master induced pluripotent stem cell (iPSC) line, a renewable cell source that enables mass production of high quality, allogeneic CAR T cells with greater product consistency, off-the-shelf availability, and broader patient accessibility. FT819 is engineered with several first-of-kind features designed to improve the safety and efficacy of CAR T-cell therapy.

Remarkable clinical outcomes have been achieved through treatment with patient-derived CAR T-cell therapy, however, next-generation approaches are necessary to reach more patients who are in need of these highly-effective therapies, said Scott Wolchko, President and Chief Executive Officer of Fate Therapeutics. Treatment of the first-ever patient with FT819 ushers in a new era for off-the-shelf CAR T-cell therapy, with the potential to overcome the real-world limitations of existing patient- and donor-derived therapeutic approaches and unlock the full potential of CAR T-cell therapy. We would like to thank our collaborators at Memorial Sloan Kettering Cancer Center, whose partnership over the past five years has profoundly contributed to this landmark achievement.

FT819 was designed to specifically address several limitations associated with the current generation of patient- and donor-derived CAR T-cell therapies. Under a collaboration with Memorial Sloan Kettering Cancer Center (MSK) led by Michel Sadelain, M.D., Ph.D., Director, Center for Cell Engineering and Head, Gene Expression and Gene Transfer Laboratory, the Company incorporated several first-of-kind features into FT819 including:

The multi-center Phase 1 clinical trial of FT819 is designed to determine the recommended Phase 2 dose and schedule of FT819 and assess its safety and clinical activity in adult patients with relapsed/refractory acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL), and B-cell lymphomas (BCL). Three treatment regimens will be independently evaluated for each type of malignancy in dose escalation: Regimen A as a single dose of FT819; Regimen B as a single dose of FT819 with IL-2 cytokine support; and Regimen C as three fractionated doses of FT819. For each indication and regimen, dose-expansion cohorts may be enrolled to further evaluate the clinical activity of FT819. The first patient with relapsed / refractory ALL was enrolled in Regimen A and received a dose of 90 million cells.

At the 24th American Society of Gene & Cell Therapy Annual Meeting held in May 2021, the Company presented preclinical data demonstrating that FT819 exhibits uniform 1XX CAR expression with complete elimination of endogenous TCR expression. The product candidate was shown to contain a stem- and central-memory T-cell phenotype, and had high-level expression of the activation marker CD25 and the trafficking marker CXCR4 and very low-level expression of the checkpoint proteins PD1, TIM3, CTLA4 and LAG3. Additionally, data from functional assessments showed that FT819 had potent antigen-specific cytolytic activity in vitro against CD19-expressing leukemia and lymphoma cell lines comparable to that of healthy donor-derived CAR T cells, and persisted and maintained tumor clearance in the bone marrow in an in vivo disseminated xenograft model of lymphoblastic leukemia.

Pursuant to a license agreement with MSK, Fate Therapeutics has an exclusive license for all human therapeutic use to U.S. Patent No. 10,370,452, which covers compositions and uses of effector T cells expressing a CAR, where such T cells are derived from a pluripotent stem cell including an iPSC. In addition to the patent rights licensed from MSK, the Company owns an extensive intellectual property portfolio that broadly covers compositions and methods for the genome editing of iPSCs using CRISPR and other nucleases, including the use of CRISPR to insert a CAR in the TRAC locus for endogenous transcriptional control.

Fate Therapeutics haslicensedintellectual propertyfrom MSK on which Dr. Sadelain is aninventor.As a result of the licensing arrangement, MSK has financial interests related to Fate Therapeutics.

About Fate Therapeutics iPSC Product PlatformThe Companys proprietary induced pluripotent stem cell (iPSC) product platform enables mass production of off-the-shelf, engineered, homogeneous cell products that are designed to be administered with multiple doses to deliver more effective pharmacologic activity, including in combination with other cancer treatments. Human iPSCs possess the unique dual properties of unlimited self-renewal and differentiation potential into all cell types of the body. The Companys first-of-kind approach involves engineering human iPSCs in a one-time genetic modification event and selecting a single engineered iPSC for maintenance as a clonal master iPSC line. Analogous to master cell lines used to manufacture biopharmaceutical drug products such as monoclonal antibodies, clonal master iPSC lines are a renewable source for manufacturing cell therapy products which are well-defined and uniform in composition, can be mass produced at significant scale in a cost-effective manner, and can be delivered off-the-shelf for patient treatment. As a result, the Companys platform is uniquely designed to overcome numerous limitations associated with the production of cell therapies using patient- or donor-sourced cells, which is logistically complex and expensive and is subject to batch-to-batch and cell-to-cell variability that can affect clinical safety and efficacy. Fate Therapeutics iPSC product platform is supported by an intellectual property portfolio of over 350 issued patents and 150 pending patent applications.

About FT819FT819 is an investigational, universal, off-the-shelf, T-cell receptor (TCR)-less CD19 chimeric antigen receptor (CAR) T-cell cancer immunotherapy derived from a clonal master induced pluripotent stem cell (iPSC) line, which is engineered with the following features designed to improve the safety and efficacy of CAR19 T-cell therapy: a novel 1XX CAR signaling domain, which has been shown to extend T-cell effector function without eliciting exhaustion; integration of the CAR19 transgene directly into the T-cell receptor alpha constant (TRAC) locus, which has been shown to promote uniform CAR19 expression and enhanced T-cell potency; and complete bi-allelic disruption of TCR expression for the prevention of graft-versus-host disease (GvHD). FT819 demonstrated antigen-specific cytolytic activity in vitro against CD19-expressing leukemia and lymphoma cell lines comparable to that of primary CAR T cells, and persisted and maintained tumor clearance in the bone marrow in an in vivo disseminated xenograft model of lymphoblastic leukemia (Valamehr et al. 2020). FT819 is being investigated in a multi-center Phase 1 clinical trial for the treatment of relapsed / refractory B-cell malignancies, including B-cell lymphoma, chronic lymphocytic leukemia, and acute lymphoblastic leukemia (NCT04629729).

About Fate Therapeutics, Inc.Fate Therapeutics is a clinical-stage biopharmaceutical company dedicated to the development of first-in-class cellular immunotherapies for patients with cancer. The Company has established a leadership position in the clinical development and manufacture of universal, off-the-shelf cell products using its proprietary induced pluripotent stem cell (iPSC) product platform. The Companys immuno-oncology pipeline includes off-the-shelf, iPSC-derived natural killer (NK) cell and T-cell product candidates, which are designed to synergize with well-established cancer therapies, including immune checkpoint inhibitors and monoclonal antibodies, and to target tumor-associated antigens using chimeric antigen receptors (CARs). Fate Therapeutics is headquartered in San Diego, CA. For more information, please visit http://www.fatetherapeutics.com.

SOURCE: Fate Therapeutics

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Fate Therapeutics Announces Treatment of First Patient in Landmark Phase 1 Clinical Trial of FT819, the First-ever iPSC-derived CAR T-Cell Therapy |...

Scientists say that base editing proved itself efficient in correcting a mutation in patient cells with the monogenic disease Alpha-1 antitrypsin deficiency (AATD). The disorder is a common inherited disease that affects the liver and the lungs.

Base editing is different from other forms of editing, including CRISPR, because the base editors do not induce a break in the DNA, which helps prevent double strand breaks, potential off-target editing, and unwanted mutations during cell repair.

Researchers at Boston Medical Center and Boston University used patient-derived liver cells (iHeps) that mimic the biology of liver hepatocytes, the main producers of alpha-1 antitrypsin protein in the body. The base editing technology corrected the Z mutation responsible for AATD and reduced the effects of the disease in the hepatocytes, demonstrating successful base editing in human cells.

The study (Adenine Base Editing Reduces Misfolded Protein Accumulation and Toxicity in Alpha-1 Antitrypsin Deficient Patient iPSC-Hepatocytes), published inMolecular Therapy,can help pave the way for future human trials, according to the research team.

AATD is most commonly caused by the Z mutation, a single base substitution that leads to AAT protein misfolding and associated liver and lung disease. In this study, we apply adenine base editors to correct the Z mutation in patient-induced pluripotent stem cells (iPSCs) and iPSC-derived hepatocytes (iHeps), wrote the investigators.

We demonstrate that correction of the Z mutation in patient iPSCs reduces aberrant AAT accumulation and increases its secretion. Adenine base editing (ABE) of differentiated iHeps decreases ER stress in edited cells as demonstrated by single-cell RNA sequencing. We find ABE to be highly efficient in iPSCs and do not identify off-target genomic mutations by whole genome sequencing.

These results reveal the feasibility and utility of base-editing to correct the Z mutation in AATD patient cells.

This study shows the successful application of base editing technology to correct the mutation responsible for AATD in liver cells derived from patients with this disease, said Andrew Wilson, MD, a pulmonologist at Boston Medical Center and an associate professor of medicine at the Boston University School of Medicine, who served as the studys corresponding author. I am hopeful that these results will create a pathway to use this technology to help patients with AATD and other monogenic diseases.

Base editors created by Beam Therapeutics were applied to induced pluripotent stem cells (iPS cells) from patients with AATD, and then again in hepatocytes that were derived from iPS cells. This was done to study the correction of the Z mutation of the gene responsible for AATD in human cells.

The Z mutation in the SERPINA1 gene is responsible for causing chronic, progressive lung and liver disease in AATD. In patients with AATD, the mutant AAT proteins misfold and form aggregates of protein that build up inside the hepatocytes and cause damage.

For this study, researchers started with mutant (ZZ) iPSCs created from a patient with AATD. After the base editing process was completed, the DNA from the edited cells was sequenced to determine if the SERPINA1 gene had been corrected. Clonal populations of cells with either one (MZ) or both copies (MM) of the corrected gene were expanded and then differentiated over the course of 25 days to generate hepatocytes.

After sequencing the entire genome of the edited cells, there was no evidence of inadvertent mutations in the genome from the base editors, and the misfolding and associated protein buildup was partially corrected in MZ cells and completely in MM normal cells.

The process was repeated using hepatocytes derived from the mutant iPSCs. Two base editors were used in different conditions to test the efficiency of this process. In the best conditions, about 50% of the mutant genes were successfully edited. The cells were then analyzed to see if they still appeared hepatic and if there were fewer signs of the disease in the edited cells, compared to mutant ZZ cells.

Findings showed the base editing did not alter the hepatic program, and the liver cells still expressed hepatic genes and proteins at normal levels. In addition, there was less accumulation of aggregated misfolded Z AAT protein, showing less evidence of disease in the edited cells.

While augmentation therapy has been shown to slow the progression of lung disease in AATD patients, there are currently no treatments available for AATD-associated liver disease. Emerging treatment strategies have focused on the correction of the Z mutation.

Base editing is being evaluated as a treatment modality for a variety of monogenic diseases, according to the scientists. Alpha-1 antitrypsin deficiency is a prime target for base editing, likely to be one of the earlier diseases in which base editors are tried in human studies. Additional disease targets include retinal disease, hereditary tyrosinemia, sickle cell anemia, progeria, cystic fibrosis, and others.

Findings of this study suggest that future research may explore the usefulness of base-editors in editing other quiescent cell populations. Additionally, it has recently been shown that base-editors can edit RNA in addition to DNA in immortalized cell lines and warrants further investigation.

By quiescent, we are referring to differentiated cells (in this case hepatocytes) that are not stem cells or cells that are actively dividing. Basically, [we are talking about] any differentiated cell type, Wilson toldGEN. This is relevant because many of the cell types in the body that you would want to target are already differentiated cells. It is in many cases easier to edit an actively dividing cell, which is why we mention this. There are many examples of a differentiated cell type in the body, such as cardiac cells, lung cells, skin cells, etc., that you might want to target.

One of the major things researchers worry about in the field of gene editing is the possibility of off-target effectsunintended consequences of applying the editing machinery.

The most likely off-target effect, in this case, would be editing of DNA somewhere in the genome other than what we intended to edit, continued Wilson. When we looked by whole genome sequencing, we didnt see evidence of this in iPS cells. However, in addition to editing DNA, it has been reported that base editors can also edit RNA. This could have unintended consequences even if the DNA sequence isnt changed.

We didnt look in this study to see if this occurred, which is why we mentioned itjust to be up front about possible unintended consequences/toxicities that could be present and that we didnt exclude. It isnt something specific to our study or gene of interest but generalizable to the entire field of base editing.

See more here:
Base Editing as Therapy for Common Inherited Lung and Liver Disease Shows Promise - Clinical OMICs News

CRISPR is revolutionary. Its also a total brute.

The classic version of the gene editing wunderkind literally slices a gene to bits just to turn it off. Its effective, yes. But its like putting an electrical wire through a paper shredder to turn off a misbehaving light bulb. Once the wires are cut, theres no going back.

Why not add a light switch instead?

This month, a team from the University of California, San Francisco (UCSF) reimagined CRISPR to do just that. Rather than directly acting on genesirrevocably dicing away or swapping genetic lettersthe new CRISPR variant targets the biological machinery that naturally turns genes on or off.

Translation? CRISPR can now flip a light switch to control geneswithout ever touching them directly. It gets better. The new tool, CRISPRoff, can cause a gene to stay silent for hundreds of generations, even when its host cells morph from stem cells into more mature cells, such as neurons. Once the sleeping beauty genes are ready to wake up, a complementary tool, CRISPRon, flips the light switch back on.

This new technology changes the game so now youre basically writing a change [into genes] that is passed down, said author Dr. Luke Gilbert. In some ways we can learn to create a version 2.0 of CRISPR-Cas9 that is safer and just as effective.

The crux is something called epigenetics. Its a whole system of chemicals and proteins that controls whether a gene is turned on or off.

If that sounds confusing, lets start with what genes actually look like inside a cell and how they turn on. By turning on, I mean that genes are made into proteinsthe stuff that builds our physical form, controls our metabolism, and makes us tick along as living, breathing humans.

Genes are embedded inside DNA chains that wrap very tightly around a core proteinkind of like bacon-wrapped asparagus. For genes to turn on, the first step is that they need a bunch of proteins to gently yank the DNA chain off the asparagus, so that the genes are now free-floating inside their cellular space capsule, called the nucleus.

Once that chunk of bacon-y DNA is free, more proteins rush over to grab onto the gene. Theyll then roll down the genes nucleotides (A, T, C, and G) like a lawn mower. Instead of mulch, however, this biological machine spews out a messenger that tells the cell to start making proteinsmRNAs. (Yup, the same stuff that makes some of our Covid-19 vaccines.) mRNA directs our cells protein factory to start production, and voil, that gene is now turned on!

Anything that disrupts this process nukes the genes ability to turn into proteins, essentially shutting it off. Its enormously powerfulbecause one single epigenetic machine can control hundreds or thousands of genes. Its a master light switch for the genome.

The team started with a CRISPR system that has a neutered Cas9. This means that the protein normally involved in cutting a gene, Cas9, can no longer snip DNA, even when tethered to the correct spot by the other component, the guide RNA bloodhound. They then tacked on a protein thats involved in switching off genes to this version of CRISPR.

Heres the clever part: the protein is designed to hijack a natural epigenetic process for switching genes off. Genes are often shut down through a natural process called methylation. Normally, the process is transient and reversible on a gene. CRISPRoff commandeers this process, in turn shutting down any targeted gene but for a far longer period of timewithout physically ripping the gene apart.

Thanks to epigenetics enhancing power, CRISPRoff lets researchers go big. In one experiment targeting over 20,000 genes inside immortalized human kidney cells with CRISPRoff, the team was able to reliably shut those genes off.

Not satisfied with a one-way street, the team next engineered a similar CRISPR variant, with a different epigenetics-related protein, dubbed CRISPRon. In cells inside petri dishes, CRISPRon was able to override CRISPRoff, and in turn, flip the genes back on.

We now have a simple tool that can silence the vast majority of genes, said study author Dr. Jonathan Weissman. We can do this for multiple genes at the same time without any DNA damage and in a way that can be reversed.

Even crazier, the off switch lasted through generations. When the team turned off a gene related to the immune system, it persisted for 15 monthsafter about 450 cellular generations.

The edits also lasted through a fundamental transformation, that is, a cells journey from an induced pluripotent stem cell (iPSC) to a neuron. iPSCs often start as skin cells, and are rejuvenated into stem cells through a chemical bath, when they then take a second voyage to become neurons. This process often wipes away epigenetic changes. But to the authors surprise, CRISPRoffs influence remained through the transformations. In one experiment, the team found that shutting off a gene related to Alzheimers in iPSCs also reduced the amount of subsequently encoded toxic proteins in the resulting neurons.

What we showed is that this is a viable strategy for silencing Tau and preventing that protein from being expressed, said Weissman, highlighting just one way CRISPRoffand controlling the epigenome in generalcan alter medicine.

This isnt the first time someones tried to target the epigenome with CRISPR. The same team previously experimented with another set of CRISPR variants that tried the same thing. The difference between the two is time and stability. With the previous setup, scientists struggled to keep the light switch off for a single generation. The new one has no trouble maintaining any changes through multiple divisionsand transformationsin the genome.

A reliable CRISPR tool for epigenetics is insanely powerful. Although we have drugs that work in similar ways, theyre far less accurate and come with a dose of side effects. For now, however, CRISPRoff and CRISPRon only work in cells in petri dishes, and the next step towards genomic supremacy would be to ensure they work in living beings.

If thats the case, it could change genetic editing forever. From reprogramming biological circuits in synthetic biology to hijacking or reversing ones to prevent disease, epigenetic reprogramming offers a way to do it all without ever touching a gene, nixing the threat of mutationswhile leading to lasting effects through generations.

I think our tool really allows us to begin to study the mechanism of heritability, especially epigenetic heritability, which is a huge question in the biomedical sciences, said study author Dr. James Nuez.

Image Credit: nobeastsofierce/Shutterstock.com

Read more:
A New CRISPR Tool Flips Genes On and Off Like a Light Switch - Singularity Hub