Microparticles in Three Dimensional Thrombus Formation

Abstract

Thrombosis is the formation of a blood clot under pathological conditions. The growth of thrombi may be accelerated by the presence of circulating cell-derived vesicles, termed microparticles (MPs). Previous studies have primarily focused on platelet deposition whereas research regarding MP transport has not been studied under controlled flow conditions. The purpose of this study was to understand MP deposition within platelet thrombi under different flow conditions in order to predict and their possible role in thrombosis. This study utilized perfusion chambers with well-defined flow conditions to visualize platelet or platelet and MP deposition from whole human blood using confocal microscopy. The two devices produced parallel, streamlined flow or recirculating flow. Platelet thrombi formation did not consistently increase with increasing wall shear rate, likely due to reduced platelet aggregation on monomeric collagen. MP deposition within platelet thrombi, however, increased with increasing wall shear rate. Platelet thrombi surface area was increased in the recirculation zone, as expected. However, there was no clear difference in MP deposition within thrombi in the recirculation zone. Donor to donor variability indicates that additional studies may be required in order to demonstrate differences. In addition, MPs counts and deposition location may provide greater insight as compared to surface area.