Mechanical Characterization of Vascular Endothelial Cells Exposed to Fluid Shear Stress

Abstract

Vascular endothelial cells are constantly exposed to shear stress generated by blood flow and respond by exhibiting alterations in morphology and cytoskeletal structures as well as by modulating cell physiological functions. Since endothelial cell responses to fluid shear stress have been implicated in the localization of atherosclerosis, the effects of fluid shear stress on endothelial cell morphology and functions have been exclusively studied. Interestingly, atherosclerosis occurs primarily at branching and curving regions of arterial walls, where endothelial cells would experience complex blood flow patterns. So far, a lot of efforts have been made to study endothelial mechanotransduction to flow, indicating the fact that after applying fluid shear stress, endothelial cells exhibit marked elongation and orientation in the direction of flow. The need for experimental techniques for studying endothelial cell responses to flow has lead to the development of different types of flow chambers. Conventional flow chambers include a cone-and-plate flow chamber and a parallel-plate flow chamber, while more recently, microfluidic flow chambers have emerged with a great potential for a high throughput analysis. In this chapter, many types of flow chambers are first summarized. Stiffness change of sheared endothelial cells has been be of great interest in particular for mechanical engineering researchers because endothelial cells may change their morphology and cytoskeletal structures in response to fluid shear stress. Therefore, AFM (Atomic Force Microscopy) stiffness measurement of sheared endothelial cells is then described. Lastly, stiffness change of sheared endothelial cell nuclei measured with a pipette aspiration test is also presented.