Mechanical mechanisms for thrombosis in microvessels

The hypothesis that thrombus can be induced in curved vessels due to mechanical stimuli was tested both experimentally and computationally. Our in vivo experiments on rat mesentery showed that thrombi could be formed in non-injured stretched/curved microvessels (post-capillary venules, 20-50 micrometer in diameter), and they were initiated at the inner side of the curvature. To investigate the mechanical mechanisms of the thrombus formation, we performed 3-D computational simulation using commercial software, FLUENT. Vessels with different curvatures (90deg and 180deg) as well as different shaped-cross sections (circular and elliptic) were considered. Our computational results demonstrated that the shear rate and shear rate gradient at the inner side of the curve were higher than those at the opposite side. The differences became larger in more bended and elliptic-shaped microvessels. This suggested that higher shear rate and shear rate gradient are two of the factors that initiate the thrombosis in curved post-capillary venules. Our results are consistent with others in branched venules [1].