Acceleration of skeletal muscle regeneration in a rat skeletal muscle injury model by local injection of human peripheral blood-derived CD133-positive cells.

Muscle injuries in sport activities can pose challenging problems in traumatology and sports medicine. The best treatment for muscle injury has not been clearly established except for the conservative treatment that is routinely performed. We investigated the potential of human adult CD133+ cells to contribute to skeletal muscle regeneration in an athymic rat model. We tested whether CD133+ cells locally transplanted to the skeletal muscle lacerated models could (a) induce vasculogenesis/angiogenesis, (b) differentiate into endothelial and myogenic lineages, and (c) finally promote histological and functional skeletal myogenesis. Granulocyte colony stimulating factor-mobilized peripheral blood (PB) CD133+ cells, PB mononuclear cells, or phosphate-buffered saline was locally injected after creating a muscle laceration in the tibialis anterior muscle in athymic rats. After treatment, histological and functional skeletal myogenesis was observed significantly in the CD133+ group. The injected CD133+ cells differentiated into endothelial and myogenic lineages. Using real-time polymerase chain reaction analysis, we found that the gene expressions related to microenvironment conduction for host angiogenesis, fibrosis, and myogenesis were ideally up/downregulated. Our results show that CD133+ cells have the potential to enhance the histological and functional recovery from skeletal muscle injury rather via indirect contribution to environment conduction for muscular regeneration. It would be relatively easy to purify this cell fraction from PB, which could be a feasible and attractive autologous candidate for skeletal muscle injuries in a clinical setting. These advantages could accelerate the progression of cell-based therapies for skeletal muscle injuries from laboratory to clinical implementation.