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Efficient myogenic differentiation of murine dermal Sca-1 (−) cells via initial aggregation culture.

Stem cells from various organs have been shown to regenerate muscle cells. Among them, skin-derived cells are promising because of their easy accessibility. We separated murine dermal cells into Sca-1 (+) and (−) fractions and investigated which of them could differentiate into muscle cells. After the cells were aggregated for 4 days and cultured on a collagen type I-coated plate for 7–10 days, the Sca-1 (−) fraction had expanded into many myoblastic cells, but the Sca-1 (+) fraction had not. Initial commitment to the myogenic lineage appeared to start during the aggregation. Sca-1 (−) cells proliferated exponentially and maintained their ability to differentiate into skeletal muscle cells within 7–10 days. About 60% of the cells showed positive staining for skeletal fast myosin heavy chain. Transplantation experiments revealed that the myoblastic cells arising after several passages were successfully engrafted into damaged host muscle. In conclusion, we have found that murine dermal Sca-1 (−) cells differentiate into muscle cells in vitro and in vivo after using an initial aggregation procedure. Their high differentiation efficiency and proliferation ability will offer substantial advantages for stem cell research.