Muscles have a pool of stem cells which provides a source for muscle growth and for regeneration of injured muscles. The stem cells must reside in special niches of the muscle for efficient growth and repair. The developmental biologists Dr. Dominique Br-hl and Prof. Carmen Birchmeier of the Max Delbr-ck Center for Molecular Medicine (MDC) Berlin-Buch have elucidated how these stem cells colonize these niches. At the same time, they show that the stem cells weaken when, due to a mutation, they locate outside of the muscle fibers instead of in their stem cell niches.
Muscle stem cells, also called satellite cells, colonize a niche that is located between the plasma membrane of the muscle cell and the surrounding basal lamina. Already in newborns these niches contain satellite cells from which both muscle cells and new stem cells can be generated.
In the present study Dr. Br-hl and Professor Birchmeier showed that mouse muscle progenitor cells lacking components of the Notch signaling pathway cannot colonize their niche. Instead the muscle progenitor cells locate in tissue between the muscle fibers.