Myoblast transplantation: a possible surgical treatment for a severe pediatric disease

Rapamycin represses myotube hypertrophy and preserves viability of C2C12 cells during myogenesis in vitro

BACKGROUND

Rapamycin (RAPA) has been successfully used for myoblast allotransplantation in X chromosome-linked muscular dystrophy mice. However, the mechanism of skeletal myogenesis, particularly in starved condition by RAPA, remains elusive. For this reason, we investigated the effect of RAPA on C2C12 myogenesis in serum-starved condition.

METHODS

Serum-free treated C2C12 cells were mimicked as skeletal myogenesis in nutrition shortage microenvironment. A methylthiazoletetrazolium (MTT) assay was used to investigate different RAPA concentrations on serum-free treated C2C12 cells and the following assays were used to detect the characteristic of C2C12 myogenesis by RAPA in vitro.

RESULTS

We found that 150 ng/mL of RAPA did not significantly suppress the viability of C2C12 differentiated cells by MTT assay. The RAPA concentration could protect myoblast serum-starved cells effectively from apoptosis through flow cytometry and retain myogenic regulatory factors through quantitative polymerase chain reaction analysis. However, RAPA significantly suppressed cell migration in wound healing assay (P<0.05). Morphological analyses indicated that RAPA also significantly suppressed myotube hypertrophy in serum-starved C2C12 cells. Western blot analysis revealed that the ratio of phosphate extracellular signal-regulated kinase/extracellular signal-regulated kinase and the protein level of p-Akt decreased in the proliferation medium and in the differentiation medium, respectively.

CONCLUSION

These findings suggest that myoblast cells are sensitive to RAPA under a serum-starved microenvironment. As an immunosuppressive agent, RAPA shall be used as a considering dosage and as a safe strategy for future myoblast allotransplantation.

Generation of skeletal muscle cells from embryonic and induced pluripotent stem cells as an in vitro model and for therapy of muscular dystrophies

Muscular dystrophies (MDs) are a heterogeneous group of inherited disorders characterized by progressive muscle wasting and weakness likely associated with exhaustion of muscle regeneration potential. At present, no cures or efficacious treatments are available for these diseases, but cell transplantation could be a potential therapeutic strategy. Transplantation of myoblasts using satellite cells or other myogenic cell populations has been attempted to promote muscle regeneration, based on the hypothesis that the donor cells repopulate the muscle and contribute to its regeneration. Embryonic stem cells (ESCs) and more recently induced pluripotent stem cells (iPSCs) could generate an unlimited source of differentiated cell types, including myogenic cells. Here we review the literature regarding the generation of myogenic cells considering the main techniques employed to date to elicit efficient differentiation of human and murine ESCs or iPSCs into skeletal muscle. We also critically analyse the possibility of using these cellular populations as an alternative source of myogenic cells for cell therapy of MDs.