Skeletal muscle aging – Stem cells in the spotlight

•During aging signaling pathways important during development are upregulated in muscle stem cells.•Aged muscle stem cells show mitochondrial dysfunction and reduced autophagic activity.•Systemic changes and changes in the stem cell niche impair muscle stem cell function in the aged. Aging is characterized by a progressive decline in tissue and organ function often linked to a reduced stem cell functionality, a cell population important for regeneration. Skeletal muscle mass and regenerative capacity decrease with advancing age. Muscle stem cells, also termed satellite cells, are a prerequisite for regeneration of skeletal muscle. Their functionality declines with increasing age, driven by intrinsic changes and changes in the stem cell niche. Here, we discuss the current understanding how muscle stem cells are affected during aging. The aging associated alterations include among others upregulation of developmental pathways in aged muscle stem cells and changes in the extracellular matrix.