Disruptive effect of impinging jet flow environment on the integrity of endothelial monolayer

Abnormal hemodynamic conditions caused by a blood jet flow impinging on the aortic wall have been considered to be involved in the pathogenesis of aortic disease. Aortic diseases are generally accompanied by dysfunction and damage of the endothelial cells (ECs) lining the inner surface of blood vessels; however, the details of the effect of impinging jet flow on ECs remain unclear. In the present study, we investigated the effect of impinging jet flow conditions on the integrity of an EC monolayer. Human aortic ECs were exposed to an impinging jet flow with a maximum wall shear stress (WSS) of 18.6 Pa for 2 h in a newly developed cylindrical T-shaped flow chamber. Consequently, the ECs were detached only in the region where the WSS and normal flow velocity immediately above the wall were high. Decreased expression of the intercellular junction molecule, PECAM-1, was also observed in this region. Multiple regression analysis revealed that EC density and PECAM-1 expression were significantly correlated with not only the WSS and WSS gradient but also the normal flow velocity. Our findings suggest that the distinctive mechanical environment under an impinging jet flow may disrupt endothelial integrity.