Robust inflammatory and fibrotic signaling following volumetric muscle loss: a barrier to muscle regeneration

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.