Contribution of stem cells to skeletal muscle regeneration.

Stem cells for skeletal muscle originate from dermomyotome of the embryo. The early marker of these cells is expression of both transcription factors Pax3 and Pax7 (Pax3+/Pax7+ cells). The skeletal muscles in the adult organism have a remarkable ability to regenerate. Skeletal muscle damage induces degenerative phase, followed by activation of inflammatory and satellite cells. The satellite cells are quiescent myogenic precursor cells located between the basal membrane and the sarcolemma of myofiber and they are characterized by Pax7 expression. Activation of the satellite cells is regulated by muscle growth and chemokines. Apart from the satellite cells, a population of adult stem cells (muscle side population--mSP) exists in the skeletal muscles. Moreover, the cells trafficking from different tissues may be involved in the regeneration of damaged muscle. Trafficking of cells in the process of damaged muscle regeneration may be traced in the SCID mice.