Botulinum Toxin Type A Inhibits α-Smooth Muscle Actin and Myosin II Expression in Fibroblasts Derived From Scar Contracture

Background: Scar contracture (SC) is one of the most common complications resulting from major burn injuries. Numerous treatments are currently available but they do not always yield excellent therapeutic results. Recent reports suggest that botulinum toxin type A (BTXA) is effective at reducing SC clinically, but the molecular mechanism for this action is unknown. alpha-Smooth muscle actin (alpha-SMA) and myosin II are the main components of stress fibers, which are the contractile structures of fibroblasts. The effects of BTXA on alpha-SMA and myosin II in SC are still unknown. This study aimed to explore the effect of BTXA on alpha-SMA and myosin II expression in fibroblasts derived from SC and to elucidate its actual mechanism further. Methods: Fibroblasts were isolated from tissue specimens of SC. Fibroblasts were cultured in Dulbecco modified Eagle medium with different concentrations of BTXA and their proliferation was analyzed through the tetrazolium-based colorimetric method at 1, 4, and 7 days. Proteins of alpha-SMA and myosin II were checked using Western blot in fibroblasts treated with different concentrations of BTXA at 1, 4, and 7 days. Results: Fibroblasts without BTXA treatment had a higher proliferation than that in other groups, which indicated that the proliferation of fibroblasts was significantly inhibited by BTXA (P < 0.05). Proteins of alpha-SMA and myosin II between fibroblasts with BTXA and fibroblasts without BTXA are statistically significant (P < 0.05). Conclusions: These results suggest that BTXA effectively inhibited the growth of fibroblasts derived from SC and reduced the expression of alpha-SMA and myosin II, which provided theoretical support for the application of BTXA to control SC.