Effect of low wall shear stress on the morphology of endothelial cells and its evaluation indicators

This study is designed to explore the morphological changes of endothelial cells (ECs) under different levels of shear stress and find the effective evaluation indicators with in vivo and in vitro experiments.

Human umbilical vein endothelial cells (HUVECs) and Sprague-Dawley rats were used to study the effect of different shear stress which applied by means of parallel plate-flow chamber and abdominal aorta banding model on the morphology of endothelial cells. Then, fluorescence images were acquired by means of a confocal laser-scanning microscope. Finally, Cell morphological indicators were extracted by SRAD-MCW computer image processing algorithm for quantitative analysis.

1) The morphological changes of HUVECs were observed after exposure to shear stress for 6 h, the HUVECs were elongated and spindle-shaped. And the degree of cell deformability was different while the exposure time was different, then it became stable after 18 h. The HUVECs exposure to high shear stress (HSS) exhibited an ordered cell arrangement, while the HUVECs exposure to low shear stress (LSS) showed a disordered cell arrangement. 2) Traditional cell morphological indicators such as area, perimeter, long axis diameter, short axis diameter and orientation angle were not significantly different between the normal shear stress (NSS) group and the LSS group (P > 0.05), but the intercellular space characteristics such as the junction length per unit area and the triple points per unit area were significantly different (P < 0.05).

These results demonstrate that the size and duration of shear stress can affect the morphology and arrangement of endothelial cells. The commonly used evaluation indicators for studying the effect of shear stress on the morphology of endothelial cells, including area, perimeter, long axis diameter, short axis diameter and orientation angle, etc., had no significant statistical significance, while the intercellular space characteristics including the junction length per unit area and the triple points per unit area can be used as effective indicator to study the effect of shear stress on the morphology of endothelial cells.