Response of human endothelial cells to the vortex flow in an immediately expanding flow chamber

Abstract

Complex blood flow patterns play a significant role in atherogenesis. Multiple studies have reported that early lesion occurs primarily in the regions of flow separation, vortex, and complex flow patterns. To elucidate these dynamic factors in detail and at a cellular level, the responses of endothelial cells to complex flow patterns should be investigated. In this study, an immediately expanding flow chamber was designed to investigate the effects of vortex and shear stress gradient on the morphological response of cultured endothelial cells. In the flow chamber, a pair of vortices were observed in the immediately expanding area. The shear stress profile and streamline were confirmed through computational fluid dynamics analysis. Human umbilical vein endothelial cells (HUVECs) were cultured on a cell culture dish, and the dish was set in the flow channel. The shear stress in the outlet and main flow regions was set to 2 Pa, and HUVECs were exposed to the flow for 24 h. After flow exposure, the F-actin structure and cell morphology of HUVECs were observed. After exposure to shear stress for 24 h in the central region, HUVECs showed elongation and alignment parallel to the flow direction, accompanied by the development of actin stress fibers. In contrast, the HUVECs exposed to the flow in the vortex region were randomly oriented and exhibited the formation of stress fibers; thus, it can be concluded that the vortex flow suppressed the flow-induced morphological remodeling of cells and induced the inflammatory response of HUVECs.