How blood flow shapes neointima

Blood flow and associated fluid shear stress play a role in the regulation of vascular morphogenesis during embryonic development and adaptive alterations in response to physiological and pathological stimuli. Various flow patterns, including laminar and vortex flow, in association with different levels of fluid shear stress are present in the vascular system. As fluid shear stress negatively regulates the mitogenic activities of vascular cells and molecular transport processes in the circulator system, nonuniform shear stress exerts profound effects on the formation of thrombus and neointima. In this study, we showed, by using an experimental model of polymeric cylinder implantation to the rat vena cava, that fluid shear stress controlled the development of thrombus and neointima. The degree of thrombus/neointima development was inversely correlated to the shear stress level, resulting in the formation of thrombus/neointima with a shear stress-dependent geometry and size. Furthermore, shear stress gradients controlled smooth muscle cell migration from the host-vessel media to the thrombus/neointima via the mediation of cell density gradients established under the influence of nonuniform shear stress. This paper addresses how nonuniform fluid shear stress controls the formation of thrombus/neointima and smooth muscle cell migration.