Myogenic differentiation potential of an oral mucosa-derived progenitor population

Objectives: Adult mesenchymal stem cells have been reported to form skeletal muscle in vitro. Myogenesis is characterized by a period of myoblast proliferation, followed by expression of muscle-specific proteins and subsequent fusion to form multinucleated myotubes, which can be identified via morphology (phase-contrast) and immunohistochemistry (muscle-specific proteins). Within the oral mucosa lamina propria (OMLP) a fraction of cells have been demonstrated to express gene markers of pluripotency, supporting a hypothesis that there exists a progenitor cell population that may have the potential to differentiate down a variety of lineages including muscle.

Methods: Progenitor cells (PCs) were derived by a fibronectin differential adhesion protocol. Clones were cultured in a myogenic media to stimulate cellular differentiation/fusion. Base-line characterisation of undifferentiated clones and post-differentiation populations were investigated at the RNA and protein-level.

Results: In their undifferentiated state OMLP PCs lacked expression of the myogenic marker Desmin. On culture in myogenic medium enriched with IGF-1 and glucocorticoids (hydrocortisone, dexamethasone), there was induction of expression of Desmin. Morphologically, populations noticeably altered to a large, more flattened phenotype displaying numerous filopodia, this is not however characteristic of myotubes as evidenced by those features observed during the differentiation of the C2C12 mouse myoblast cell line.

Conclusions: The expression of Desmin indicates that through a modified cell culture method it is possible to drive OMLP cells toward a myogenic pathway. Despite experimentation with several in vitro culture media conditions we have not yet visualised the myotube phenotype. Work is required to refine the requirements for cell fusion. The production of a stable myoblast population with the ability to form myotubes would enable the development of in vitro methods for culturing skeletal muscle for research purposes. In addition, it could also prove invaluable as a source of cells for muscle transplantation and regenerative therapies.