Cell Structure Controls Endothelial Cell Migration under Fluid Shear Stress

Cobblestone-shaped endothelial cells in confluent monolayers undergo triphasic mechanotaxis in response to steady unidirectional shear stress, but cells that are elongated and aligned on micropatterned substrates do not change their migration behavior in response to either perpendicular or parallel flow. Whether mechanotaxis of micropatterned endothelial cell layers is suppressed by elongated cytoskeletal structure or limited availability of adhesion area remains unknown. In this study, cells were examined on wide (100–200 μm) micropatterned lines after onset of shear stress. Cells in center regions of the lines exhibited cobblestone morphology and triphasic mechanotaxis behavior similar to that in unpatterned monolayers, whereas cells along the edges migrated parallel to the line axis regardless of the flow direction. When scratch wounds were created perpendicular to the micropatterned lines, the cells became less elongated before migrating into the denuded area. In sparsely populated lines oriented perpendicular to the flow direction, elongated cells along the upstream edge migrated parallel to the edge for 7 h before migrating parallel to the shear stress direction, even though adhesion area existed in the downstream direction. Thus, cytoskeletal structure and not available adhesion area serves as the dominant factor in determining whether endothelial mechanotaxis occurs in response to shear stress.