Distinguishing endothelial responses to impinging flow, elevated wall shear stress and wall shear stress gradient

Cerebral aneurysms develop at sites where flow impinges on the vessel wall and accelerates downstream, producing high Wall Shear Stress Gradients (WSSGs) and Wall Shear Stresses (WSSs) exceeding 100 dynes/cm(2) [1]. To distinguish endothelial cell (EC) responses to impinging flow, high WSSG, high WSS, and hypertension, two novel in vitro systems were used: A tapered cell chamber that produced WSS values from 20-160 dynes/cm(2) revealed that EC proliferation increases with WSS and high systemic pressure inhibits this proliferation. In a second chamber, a flow jet impinged on a monolayer of ECs creating distinct regions: stagnation, high WSSG combined with high WSS, and persistent high WSS. Results suggest that ECs proliferate in the stagnation region and migrate downstream to the high WSS and high positive WSSG regions.