Effect Of In-vitro Simulated Physiological Shear Stress On Endothelial Cells

Hematologic diseases,cardiovascular diseases,cancers are closely related to the blood flow shear stress.Sickle cell disease,a kind of hematologic diseases,is mainly caused by shape-change of red blood cells.Many cardiovascular diseases are caused by thrombosis or atherosclerosis.And the blood flow shear stress will change significantly around these plaques.Endothelial cells,the main component of the blood vessel wall,are susceptible to shear stress and participate in maintaining blood vessel homeostasis.Exploring the effect of shear stress on endothelial cells is of great significance for the study of the above diseases.In this paper,we designed a microfluidic device to simulate the physiological flow shear stress.And human umbilical vein endothelial cells(HUVECs)were cultured in this microfluidic chip.Then the effects of shear stress on the HUVECs were studied,including,morphology,arrangement and adhesion.We designed a microfluidic chip with real-time adjustment of large-scale shear stress.We obtained the multiple relationship between the maximum value and the minimum value of the shear stress in the chip by theoretical analysis and numerical simulation.The precise microfluidic chips were manufactured by techniques such as photolithography and soft etching.HUVECs were cultured in the microfluidic chip,and the optimal concentration(100%)and optimal incubation time(>3 hours)of the fetal bovine serum for the cells cultured in the microfluidic chip were obtained,which ensures the normal growth of HUVECs in the microfluidic chip.HUVECs.were exposed to different shear stresses(16.3,8.3,3.9,0.8,0.217,0.065,0 dyn/cm~2).By taking time-lapse photographs and analyzing the phase contrast photos,we could conclude that cells became elongated and arranged along the direction of the fluid shear stress after exposure to the shear stress of 16.7dyn/cm~2 for 24 hours.While the arrangement and morphology of cells cultured under other shear stress(3.9,0.8,0.217,0.065,0 dyn/cm~2)are similar to those under static culture.At the same time,this article verifies that would detach with step-increased shear stress,and cells would detach in 2 minutes if the shear stress reach 420 dyn/cm~2 or more.The microfluidic device developed in this article for simulating physiological flow shear stress in vitro is an innovation.It could generate a wide range of fluid shear stress,and the study of the response of endothelial cells to shear stress will be significant for understanding various cardiovascular disease.