TGFBI Facilitates Myogenesis and Limits Fibrosis in Mouse Skeletal Muscle Regeneration.

Skeletal muscles are essential for movement and support but are vulnerable to injury. Muscle regeneration relies on the extracellular matrix (ECM), which regulates key cellular processes. Transforming growth factor β-induced (TGFBI), an ECM component involved in cell adhesion, migration, and tissue development, has not been investigated in skeletal muscle regeneration. Here, we examined the role of TGFBI using Tgfbi knockout (KO) mice and C2C12 myoblasts. In vitro, C2C12 cells were treated with recombinant TGFBI following snake venom (SV)-induced injury, and myogenic differentiation and fusion were evaluated by quantitative real-time PCR (qRT-PCR) and Western blotting. In vivo, acute muscle injury was induced by SV injection into the tibialis anterior muscles of 12-week-old wild-type and Tgfbi KO mice, with regeneration assessed by histology and qRT-PCR. TGFBI was absent in uninjured muscle and C2C12 cells but was upregulated after injury. Recombinant TGFBI enhanced myogenic differentiation and restored SV-induced downregulation of myogenic and fusion markers. Although phenotypically normal under physiological conditions, Tgfbi KO mice exhibited impaired regeneration, characterized by persistent immature myofibers, elevated inflammatory cytokines, reduced myogenic marker expression, and increased fibrosis. These findings reveal TGFBI as a key regulator of skeletal muscle repair and a potential therapeutic target for muscle-related disorders.