Tissue-resident mesenchymal stem/progenitor cells in skeletal muscle: collaborators or saboteurs?

Abstract

Although the regenerative potential of adult skeletal muscle is maintained by satellite cells, other stem/progenitor cell populations also reside in skeletal muscle. These heterogeneous cellular pools with mesenchymal lineage potentially play important roles in tissue homeostasis, with reciprocal collaborations between these cells and satellite cells appearing critical for effective regeneration. However, in disease settings, these mesenchymal stem/progenitors adopt a more sinister role - likely providing a major source of fibrosis, fatty tissue and extracellular matrix protein deposition in dystrophic tissue. Development of therapies for muscle degeneration therefore requires complete understanding of the multiple cell types involved and their complex interactions.

Keywords: fibro/adipogentic progenitors; mesenchymal stem cells; muscular dystrophy; myogenesis; regenerative medicine; satellite cells; skeletal muscle; stem cells; tissue regeneration.

Fig. 1

Illustration of the various populations of tissue-resident progenitors in skeletal muscle: PICs (PW1⁺/Pax7⁻ interstitial cells, green), FAPs/MSCs (fibroadipogenic progenitors/mesenchymal stem/progenitor cells, blue), vessel-associated pericytes (yellow) and satellite cells (orange) beneath the basal lamina.