Regulated and dysregulated muscle regeneration. In regulated muscle regeneration, a transient inflammatory response occurs upon injury, which includes the chemotaxis of growth factors, cytokines, macrophages, and fibroblasts. This is followed by the activation and proliferation of satellite cells. Once activated, myoblasts differentiate into myocytes, and then fuse together to form myofibers, which exhibit central nuclei. This process is primarily orchestrated by the expression of the myogenic regulatory factors. In dysregulated muscle regeneration, there is a persistent inflammatory response and overexpression of proteins such as transforming growth factor-beta1 (TGF-β1) and myostatin, which promote the formation of fibrotic tissue to replace damaged myofibers.