Advanced Therapy Medicinal Products (ATMPs) based on somatic cells expanded
, with or without genetic modification, is a rapidly growing area of drug development, even more so following the marketing ...approval of several such products. ATMPs are produced according to Good Manufacturing Practice (GMP) in authorized laboratories. Potency assays are a fundamental aspect of the quality control of the end cell products and ideally could become useful biomarkers of efficacy
. Here we summarize the state of the art with regard to potency assays used for the assessment of the quality of the major ATMPs used clinic settings. We also review the data available on biomarkers that may substitute more complex functional potency tests and predict the efficacy
of these cell-based drugs.
Satellite cells are responsible for skeletal muscle regeneration. Upon activation, they proliferate as transient amplifying myoblasts, most of which fuse into regenerating myofibers. Despite their ...remarkable differentiation potential, these cells have limited migration capacity, which curtails clinical use for widespread forms of muscular dystrophy. Conversely, skeletal muscle perivascular cells have less myogenic potential but better migration capacity than satellite cells. Here we show that modulation of Notch and PDGF pathways, involved in developmental specification of pericytes, induces perivascular cell features in adult mouse and human satellite cell-derived myoblasts. DLL4 and PDGF-BB-treated cells express markers of perivascular cells and associate with endothelial networks while also upregulating markers of satellite cell self-renewal. Moreover, treated cells acquire trans-endothelial migration ability while remaining capable of engrafting skeletal muscle upon intramuscular transplantation. These results extend our understanding of muscle stem cell fate plasticity and provide a druggable pathway with clinical relevance for muscle cell therapy.
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•DLL4 and PDGF-BB change satellite cell morphology, proliferation, and differentiation•DLL4 and PDGF-BB induce both perivascular and satellite cell gene expression•Treated satellite cells acquire perivascular cell properties and improved migration•Human satellite cell-derived myoblasts respond to DLL4 and PDGF-BB treatment
Gerli and Moyle and colleagues show that treatment with molecules involved in developmental specification of pericytes (DLL4 and PDGF-BB) alters satellite cell fate and provides them with features potentially relevant for novel cell therapy protocols.
The aim of this study was to verify whether macrophages influence the fate of transplanted mesoangioblasts--vessel-associated myogenic precursors--in a model of sterile toxin-induced skeletal muscle ...injury. We have observed that in the absence of macrophages, transplanted mesoangioblasts do not yield novel fibers. Macrophages retrieved from skeletal muscles at various times after injury display features that resemble those of immunoregulatory macrophages. Indeed, they secrete IL-10 and express CD206 and CD163 membrane receptors and high amounts of arginase I. We have reconstituted the muscle-associated macrophage population by injecting polarized macrophages before mesoangioblast injection: alternatively activated, immunoregulatory macrophages only support mesoangioblast survival and function. This action depends on the secretion of IL-10 in the tissue. Our results reveal an unanticipated role for tissue macrophages in mesoangioblast function. Consequently, the treatment of muscle disorders with mesoangioblasts should take into consideration coexisting inflammatory pathways, whose activation may prove crucial for its success.
Duchenne muscular dystrophy (DMD) is a common X-linked disease characterized by widespread muscle damage that invariably leads to paralysis and death. There is currently no therapy for this disease. ...Here we report that a subpopulation of circulating cells expressing AC133, a well-characterized marker of hematopoietic stem cells, also expresses early myogenic markers. Freshly isolated, circulating AC133(+) cells were induced to undergo myogenesis when cocultured with myogenic cells or exposed to Wnt-producing cells in vitro and when delivered in vivo through the arterial circulation or directly into the muscles of transgenic scid/mdx mice (which allow survival of human cells). Injected cells also localized under the basal lamina of host muscle fibers and expressed satellite cell markers such as M-cadherin and MYF5. Furthermore, functional tests of injected muscles revealed a substantial recovery of force after treatment. As these cells can be isolated from the blood, manipulated in vitro, and delivered through the circulation, they represent a possible tool for future cell therapy applications in DMD disease or other muscular dystrophies.
Duchenne muscular dystrophy (DMD) is a common X-linked disease characterized by widespread muscle damage that invariably leads to paralysis and death. There is currently no therapy for this disease. ...Here we report that a subpopulation of circulating cells expressing AC133, a well-characterized marker of hematopoietic stem cells, also expresses early myogenic markers. Freshly isolated, circulating AC133
+
cells were induced to undergo myogenesis when cocultured with myogenic cells or exposed to Wnt-producing cells in vitro and when delivered in vivo through the arterial circulation or directly into the muscles of transgenic
scid/mdx
mice (which allow survival of human cells). Injected cells also localized under the basal lamina of host muscle fibers and expressed satellite cell markers such as M-cadherin and MYF5. Furthermore, functional tests of injected muscles revealed a substantial recovery of force after treatment. As these cells can be isolated from the blood, manipulated in vitro, and delivered through the circulation, they represent a possible tool for future cell therapy applications in DMD disease or other muscular dystrophies.
Cell-transplantation therapies have attracted attention as treatments for skeletal-muscle disorders; however, such research has been severely limited by poor cell survival. Tissue engineering offers ...a potential solution to this problem by providing biomaterial adjuvants that improve survival and engraftment of donor cells.
In this study, we investigated the use of intra-muscular transplantation of mesoangioblasts (vessel-associated progenitor cells), delivered with an injectable hydrogel biomaterial directly into the tibialis anterior (TA) muscle of acutely injured or dystrophic mice. The hydrogel cell carrier, made from a polyethylene glycol-fibrinogen (PF) matrix, is polymerized in situ together with mesoangioblasts to form a resorbable cellularized implant.
Mice treated with PF and mesoangioblasts showed enhanced cell engraftment as a result of increased survival and differentiation compared with the same cell population injected in aqueous saline solution.
Both PF and mesoangioblasts are currently undergoing separate clinical trials: their combined use may increase chances of efficacy for localized disorders of skeletal muscle.
Duchenne muscular dystrophy is a relatively common disease that affects skeletal muscle, leading to progressive paralysis and death. There is currently no resolutive therapy. We have developed a ...treatment in which we combined the effects of nitric oxide with nonsteroidal antiinflammatory activity by using HCT 1026, a nitric oxide-releasing derivative of flurbiprofen. Here, we report the results of long-term (1-year) oral treatment with HCT 1026 of two murine models for limb girdle and Duchenne muscular dystrophies (α-sarcoglycan-null and mdx mice). In both models, HCT 1026 significantly ameliorated the morphological, biochemical, and functional phenotype in the absence of secondary effects, efficiently slowing down disease progression. HCT 1026 acted by reducing inflammation, preventing muscle damage, and preserving the number and function of satellite cells. HCT 1026 was significantly more effective than the corticosteroid prednisolone, which was analyzed in parallel. As an additional beneficial effect, HCT 1026 enhanced the therapeutic efficacy of arterially delivered donor stem cells, by increasing 4-fold their ability to migrate and reconstitute muscle fibers. The therapeutic strategy we propose is not selective for a subset of mutations; it provides ground for immediate clinical experimentation with HCT 1026 alone, which is approved for use in humans; and it sets the stage for combined therapies with donor or autologous, genetically corrected stem cells.
Early activation of myogenesis in the somite depends on signals from surrounding tissues. Canonical β-catenin dependent Wnt signalling preferentially activates
Myf5. We now show, in explant ...experiments with presomitic mesoderm, that the expression of another myogenic determination factor, MyoD, depends on non-canonical Wnt signalling, probably emanating from the dorsal ectoderm. Inhibitors of PKC block MyoD expression, indicating that the intracellular Wnt pathway depends on this kinase. In the absence of Myf5 and Mrf4, this activation is only minorily affected and we identify Pax3 as the transcriptional mediator responsible for MyoD expression. When embryos expressing a constitutively active form of Pax3, PAX3–FKHR, are used for these studies in the presence of PKC inhibitors, MyoD expression is not affected, suggesting that Wnt signalling acts on the transcriptional activity of Pax3.
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