Are human and mouse satellite cells really the same?

Abstract

Satellite cells are quiescent cells located under the basal lamina of skeletal muscle fibers that contribute to muscle growth, maintenance, repair, and regeneration. Mouse satellite cells have been shown to be muscle stem cells that are able to regenerate muscle fibers and self-renew. As human skeletal muscle is also able to regenerate following injury, we assume that the human satellite cell is, like its murine equivalent, a muscle stem cell. In this review, we compare human and mouse satellite cells and highlight their similarities and differences. We discuss gaps in our knowledge of human satellite cells, compared with that of mouse satellite cells, and suggest ways in which we may advance studies on human satellite cells, particularly by finding new markers and attempting to re-create the human satellite cell niche in vitro.

Figure 1

Model of satellite cell activation and progression through the myogenic program. Quiescent satellite cells, underneath the basal lamina of muscle fibers, express Pax7 and Myf5. Upon activation, they upregulate MyoD and divide to produce a pool of muscle precursor cells (mpc). Satellite cell progeny then follow one of two fates. They may downregulate MyoD and self-renew to give rise to a Pax7+ satellite cell. Alternatively, they may differentiate, downregulating Pax7, Myf5, and MyoD and expressing MRF4 and myogenin, eventually fusing either to form new or to repair damaged myofibers.