Role of blood shear stress in the regulation of vascular smooth muscle cell migration

Smooth muscle cell (SMC) migration from the media to the intima of blood ve ssels contributes to neointimal formation and atherogenesis, Here, we demon strate how blood shear stress regulates vascular SMC migration in the encap sulating tissue of a micro-cylinder implanted in the center of the rat vena cava with the micro-cylinder perpendicular to blood flow In this model, th e micro-cylinder was exposed to a laminar flow with a known shear stress fi eld in the leading region and a vortex flow in the trailing region, After s urgery, the micro-cylinder was encapsulated by a thrombus-like tissue withi n one day, followed by SMC migration from the vena cava to the encapsulatin g tissue from day 3 to 20, SMC migration was time-dependent with a peak mig ration speed at day 5. At each given time (excluding day 1), blood shear st ress exerts an inhibitory effect on SMC migration with significantly suppre ssed SMC migration in the laminar flow region than in the stagnation, separ ation, and vortex flow regions. SMCs were relatively parallel to the shear stress direction in high shear stress regions, whereas perpendicular to the shear stress direction in low shear stress regions, These results suggest that blood shear stress plays a role in regulating SMC migration and orient ation in this model.