How are muscle cells formed by stem cells?

Answer 1

In postnatal muscle, skeletal muscle precursors (myoblasts) can be derived

from satellite cells (reserve cells located on the surface of mature myofibers) or from cells

lying beyond the myofiber, e.g., interstitial connective tissue or bone marrow. Both of

these classes of cells may have stem cell properties. In addition, the heretical idea that postmitotic myonuclei lying within mature myofibers might be able to re-form myoblasts or

stem cells is examined and related to recent observations for similar post-mitotic cardiomyocytes. In adult hearts (which previously were not considered capable of repair), the role of

replicating endogenous cardiomyocytes and the recruitment of other (stem) cells into cardiomyocytes for new cardiac muscle formation has recently attracted much attention. The

relative contribution of these various sources of precursor cells in postnatal muscles and

the factors that may enhance stem cell participation in the formation of new skeletal and

cardiac muscle in vivo are the focus of this review. We concluded that, although many endogenous cell types can be converted to skeletal muscle, the contribution of non-myogenic

cells to the formation of new postnatal skeletal muscle in vivo appears to be negligible.

Whether the recruitment of such cells to the myogenic lineage can be significantly enhanced

by specific inducers and the appropriate microenvironment is a current topic of intense interest. However, dermal fibroblasts appear promising as a realistic alternative source of exogenous myoblasts for transplantation purposes. For heart muscle, experiments showing the

participation of bone marrow-derived stem cells and endothelial cells in the repair of damaged cardiac muscle are encouraging.