The proliferation of neointimal smooth muscle cells cultured from rabbit aortic explants 15 weeks after de-endothelialization by a balloon catheter.

Endothelial denudation of rabbit aorta induces smooth muscle cell (SMC) migration and proliferation, resulting in a thickened neointima, showing features in common with atherosclerotic lesions. The SMC proliferation has been reported as a transient healing process, which regresses when the neointima is covered by regenerated endothelium. In this study, we examined the cellular proliferation of neointimal SMC, derived from denuded and from re-endothelialized areas of aortic explants. The results show that the neointimal SMC retain a higher rate of proliferation, even 15 weeks after a single endothelial injury by a balloon catheter. Neointimal SMC release more PDGF-AB and TGF-beta 1, which may play a mitogenic role for SMC proliferation. The data demonstrating that injury-induced stimulation of neointimal SMC proliferation is a persistent process, emphasize the importance of injury mechanisms of atherogenesis.