Morphological responses of cultured bovine aortic endothelial cells to fluid-imposed shear stress under sparse and colony conditions

The morphological responses of cultured bovine aortic endothelial cells to fluid-imposed shear stress under sparse and colony conditions were studied. Applied shear stress was controlled to 2 Pa and the exposure time was set to be between 1 and 24 hours. Before and after flow exposure, the shape index and the angle of cell orientation to flow direction of each individual cell were measured. In the experiment under sparse conditions, the shape index was 0.33±0.13 (mean±SD) and cells almost randomly distributed under the no-flow condition. This randomness continued following application of shear stress for 24 hours, and a morphological difference between the cells under no-flow conditions and after exposure to shear stress was not observed. In the experiment under colony conditions, the cells in the center portion of the colony were round and were randomly oriented under no-flow conditions. After exposure to shear stress for 24 hours, the cells in the center portion were elongated and aligned with the flow direction, although the cells on the periphery were randomly oriented. From these results, we conclude that the degree of cell to cell contact may affect the morphological response of endothelial cells to fluid-imposed shear stress.