Development of Novel Flow Chamber to Study Endothelial Cell Morphology: Effects of Shear Flow with Uniform Spatial Gradient on Distribution of Focal Adhesion*

Fluid shear stress (SS) is well known to cause morphological changes in vascular endothelial cells (ECs) accompanied by alteration in actin cytoskeletal structure and distribution of focal adhesions. Recent studies have shown that spatial SS gradient also has effects on EC morphology, but the detailed mechanisms of EC responses to SSG remain unclear. In the present study, we sought morphological responses of ECs under SS and uniform SSG condition using a newly developed flow chamber. Confluent ECs were exposed to SS with SSG for 24 hours. Focal adhesions of the EC under SS without SSG were localized in the cell periphery. In contrast, focal adhesions were expressed not only in the periphery but also in interior portion of cells after exposure to SS with SSG. Unlike ECs exposure to SS developed thick actin filaments aligned to the direction of flow no development of thick actin filaments but thin and short filaments were observed in ECs after 24-hour exposure to SS with SSG. Since the distribution of focal adhesion is of critical importance for development of actin filaments and cell morphological changes, these results suggest that SSG suppresses redistribution of focal adhesions, resulting in the inhibition of EC morphological changes and development of thick actin filaments in responseto flow.