Muscle regeneration following injury can be modified in vivo by immune neutralization of basic fibroblast growth factor, transforming growth factor β1 or insulin-like growth factor I

Previous in vitro studies pointed out the role played by several growth factors (basic fibroblast growth factor or bFGF, transforming growth factor beta-1 or TGFβ1, insulin-like growth factor-I or IGF-I) on the proliferation, the differentiation and the fusion of myogenic precursor cells. We attempted to modify the muscle regeneration which follows the denervation-devascularization of extensor digitorum longus in mice, by acting on the growth factors which are possibly involved in this process. The injection of neutralizing antibodies against either bFGF or IGF-I into the muscle at the time of lesion reduced the number and diameter of regenerating myofibres, suggesting a delay in proliferation and/or fusion of activated satellite cells. The neutralization of TGFβ1 led to an increased number of small regenerating myofibres, which would be due to the promoting effects of the remaining growth factors (i.e. bFGF and IGF-I) on myoblast proliferation. These contrasted results strongly suggest that the growth factors regulate in vivo muscle regeneration and would be accessible tools for future therapy of muscular disorders.