Skeletal Muscle Stem Cells: Aging and Rejuvenation.

Stem cells are central for tissue homeostasis and regeneration after stress, and their function depends on interactions with neighboring niche cells. In skeletal muscle, the resident stem cells (also called satellite cells [SCs]) decline in number and function with age, leading to loss of regenerative capacity and, eventually, deterioration of muscle integrity and physiology. Aged SCs lose the capacity to preserve quiescence or to activate and expand upon injury, in part due to changes in the local and systemic environment. Here, we focus on the age-associated intrinsic changes of SCs and the causes of their cellular and molecular decline. We discuss results from single-cell omics technologies that have shed light on the interactions between SCs and niche cells and how far-reaching signals impact SC function. We present future perspectives on rejuvenating interventions to counter age-dependent regenerative decline and the open questions in muscle stem cell aging.