Influence of fluid shear stress on cultured vascular endothelial cells

: Vascular endothelial cells modulate their functions in response to hemodynamic forces such as fluid shear stress. In the present study, we applied shear to cultured bovine aortic endothelial cells (EC) by using a saecially designed apparatus and examined the effects of their homogenate and conditioned medium on such EC and smooth muscle cell (SMC) functions as adhesion, growth, migration or collagen synthesis. Cultured bovine aortic SMC were stimulated to adhere to wells and grow in the presence of EC conditioned medium. This conditioned medium had no effect on EC adhesion and growth. The activities of stimulating SMC adhesion and growth were almost the same in both EC conditioned medium obtained from static cultures and shear-loaded cultures. Studies with filters in a modified Boyden chamber showed that shear-loaded EC homogenate yielded stimulated SMC migration. Also shear-loaded EC cell layer contained increased amount of collagen compared with static EC cell layer. These observations indicate that:(a) EC secrets the substances which stimulate SMC adhesion and growth, but these functions are not affected by shear stress application, (b) EC produces SMC migration stimulators in response to shear stress, and (c) shear stress can enhance EC collagen synthesis. These results are relevant to EC response to hemodynamic forces and its role in the localization of atherosclerotic lesions in vivo.