The basic fibroblast growth factor-saporin mitotoxin impairs in vivo skeletal regeneration following injury

Basic fibroblast growth factor (bFGF) is known to promote the proliferation of myogenic cells in vitro and has been detected in regenerating muscle in vivo. We attempted to modify in vivo post-injury muscle regeneration by acting through the potential involvement of bFGF and the presence of bFGF receptors on regenerating myogenic cells. For this purpose, bFGF conjugated to saporin, a potent mitotoxin, was injected in denervated-devascularized extensor digitorum longus of mice. Cytotoxicity occurred in the regeneration process, as shown by the significantly reduced number and the smaller diameter of the regenerating myotubes, probably determined by the binding of the toxic conjugate to bFGF receptors of myogenic cells. This study describes a suitable in vivo model to develop this specifically-mediated cytotoxicity, which offers new perspectives for acting on muscle regeneration disorders.