EFFECTS OF DISTURBED FLOW ON ENDOTHELIAL-CELLS

Atherosclerotic lesions tend to localize at curvatures and branches of the arterial system, where the local flow is often disturbed and irre gular (e.g., flow separation, recirculation, complex flow patterns, an d nonuniform shear stress distributions). The effects of such flow con ditions on cultured human umbilical vein endothelial cells (HUVECs) we re studied in vitro by using a vertical-step flow channel (VSF). Detai led shear stress distributions and flow structures have been computed by using the finite volume method in a general curvilinear Coordinate system. HUVECs in the reattachment areas with low shear stresses were generally rounded in shape. fn contrast, the cells under higher shear stresses were significantly elongated and aligned with the flow direct ion, even far those in the area with reversed flow. When HUVECs were s ubjected to shearing in VSF, their actin stress fibers reorganized in association with the morphological changes. The rate of DNA synthesis in the vicinity of the flow reattachment area was higher than that in the laminar flow area. These in vitro experiments have provided data f or the understanding of the in vivo responses of endothelial cells und er complex flow environments found in regions of prevalence of atheros clerotic lesions.