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 between 1 and 24 hours. Before and after flow exposure, the shape index and the angle of cell orientation to flow direction of each cell were measured. In the experiment under sparse condition, 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 no morphological difference between cells under the no-flow condition and those after exposure to shear stress was observed. In the experiment under colony condition, cells in the center portion of the colony were round and randomly oriented under the no-flow condition. After exposure to shear stress for 24 hours, cells in the center portion were elongated and aligned with the flow direction, although cells in the periphery were randomly oriented. From these results, we concluded that the degree of cell-to-cell contact affects the morphological response of endothelial cells to fluid-imposed shear stress.