Tenascin-C from the tissue microenvironment promotes muscle stem cell maintenance and function through Annexin A2.

Skeletal muscle regeneration occurs through the finely timed activation of resident muscle stem cells (MuSC). Following injury, MuSC exit quiescence, undergo myogenic commitment, and regenerate the muscle. This process is coordinated by tissue microenvironment cues, however the underlying mechanisms regulating MuSC function are still poorly understood. Here, we demonstrate that the extracellular matrix protein Tenascin-C (TnC) promotes MuSC self-renewal and function. Mice lacking TnC exhibit reduced number of MuSC, and defects in MuSC self-renewal, myogenic commitment, and repair. We show that fibro-adipogenic progenitors are the primary cellular source of TnC during regeneration, and that MuSC respond through the surface receptor Annexin A2. We further demonstrate that TnC declines during aging, leading to impaired MuSC function. Aged MuSC exposed to soluble TnC show a rescued ability to both migrate and self-renew in vitro. Overall, our results highlight the pivotal role of TnC during muscle repair in healthy and aging muscle.