Characteristics of Satellite Cells and Multipotent Adult Stem Cells in the Skeletal Muscle

Under resting conditions skeletal muscle is a stable tissue with a low turnover rate. Upon injury it has the ability to undergo regeneration, preventing the loss of muscle mass and function. Recent research demonstrated that satellite cells, the stem cells of adult skeletal muscle, are indispensible for muscle regeneration. Satellite cells are generated during embryonic development and persist in adult muscle. They are characterized by the expression of Pax7 and their location underneath the basal lamina of muscle fibers. In resting skeletal muscle satellite cells are mostly quiescent. They become activated during regeneration and fuse to each other generating new fibers or repair damaged ones. Satellite cells are a heterogeneous population based on the expression of two transcription factors, Myf5 and MyoD. This chapter gives an overview on satellite cell function, their heterogeneity, regulation and embryonic origin.