Skeletal muscle has a remarkable regenerative capacity, which is conferred by a pool of resident stem cells, known as satellite cells. After damage, satellite cells proliferate, differentiate, and fuse to form new or repair existing multinucleated myofibers. However, after surgical or traumatic loss of a critical mass of muscle, also known as volumetric muscle loss 1 (VML), this endogenous regenerative competence is overwhelmed. Rather VML has been shown to induce robust scar deposition, fibrotic supplantation, loss of function, and serious morbidity 2. These outcomes have been postulated to result from the ablation of resident regenerative progenitors in addition to connective tissue and basement membrane, which provide structural, biochemical, and mechanical cues to guide regeneration 3. Regenerative therapies that aim to restore these elements, such as autologous tissue or stem cell transfer 3 from an uninjured site, or implantation of an instructive scaffold 4 that recruits and guides reparative cells, have yielded incomplete recovery of muscle volume, strength, and function.

The development of successful regenerative therapies for VML has been hindered by an incomplete understanding of the molecular phenomena driving and mediating injury repair. In this issue of Cell Death and Discovery, Aguilar et al. 5 addresses this issue by characterizing the pathophysiologic response to VML using a multi-scale approach, and contrasting those results to surgical implantation of a regenerative therapy (minced muscle grafts-MMGs). The investigators tracked the molecular phenomenology after VML over 56 days using muscle function testing, histology, and gene expression