Roles of Cytoskeletal Components for the Orientation and the Permeability of Cultured Endothelial Cells Exposed to Shear Stress

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Porcine aortic endothelial cells (PAECs) were cultured and exposed to shear stress using the parallel plate flow chamber. The elongation and orientation of the cells were observed as compared to controls. This effect was highly dependent on such parameters as the level of shear stress and the duration of exposure. Staining of actin filament of endothelial cells showed changes in cytoskeletal structure prior to morphological changes of cell shape at an early stage of shear stress loading. After the flow experiment the mechanical properties were studied using the micropipette technique. The cells exposed to shear stress demonstrated a mechanical stiffness was significantly greater than that of control cells. The influence of shear stress on endothelial cell mechanical stiffness may be related to alteration in cytoskeletal structure. Using the same technique actin filaments were also shown to play important roles in viscoelastic behavior of the cells.Effects of extracellular matrices (ECM … More s) on the cell shape and the cytoskeletal structure were analyzed on PAECs. The components of ECM used were type IV collagen, heparan sulfate, chondroitin sulfate and dermatan sulfate. The PAECs cultured on the mixed ECMs showed marked elongation and segmental orientation with randomly distributed cell axis even under a no-flow condition. The actin filaments were mostly observed in parallel with the cell axis. These findings suggest that ECM is one of the most important factors that acts together with shear stress to induce the variation of endothelial cell configuration in vivo.Using the fluorescent dye-light technique platelet adhesion was found to be induced on PAECs and the platelet deposition grew on the light-irradiated area of the cells. In this in vitro thrombus model, a scanning electron microscopy showed that the platelets directly adhered to PAECs without the denudation.Experiments on the permeability through PAECs are still continued while we have tried to remodel the apparatus. Less