Review Vascular Wall Growth Control: The Role of the Endothelium

It is now generally accepted that abnormalgrowth of smooth muscle cells plays a central and characteristic role in the development of atherosclerotic lesions. We need to know the identity of the factors and mechanisms that stim-ulate this abnormal growth.1" * In contrast, issues surrounding control of endothelial growth are dif-ferent and less obvious. There is no evidence that excess growth of endothelium contributes to the formation of lesions. There is evidence, how-ever, that endothelial injury leads to proliferation and migration of smooth muscle cells into lesions as a result of the release of platelet-derived growth factor at sites where endothelial continuity is disrupted.1'2 Moreover, loss of endo-thelial integrity is also crucial to thrombosis an