(448f) Platelet Aggregation at Sites of Vascular Injury

Platelet aggregation at sites of vascular injury is necessary for hemostasis and arterial thrombosis and occurs via plateletâ??platelet adhesion, tethering and rolling on the injured endothelium, a critical initial step in blood clot formation. Smaller platelet size yielded less mural thrombus mass and smaller emboli, either with or without RBCs. Aggregation of platelets is accelerated by shear rate during blood flow. Adhesion of platelets to each other and platelets to RBC depend on collisions of elastic platelets to deformable RBC in a hydrodynamic flow with Johnson-Kendall-Roberts (JKR) models. In this way the cohesive impulse, required for the hard-sphere model, is calculated together with other parameters, namely the collision duration and the coefficient of restitution. Aggregate morphology, elastic modulus and surface energy are critical in determining adhesion to straight and tortuous capillary walls and to Red Blood Cells for required optimizing coagulation. Model predictions on platelet to platelet collisions and of platelets to the capillary wall showed that platelet size, platelet Youngâ??s modulus and shear rate are most significant variables controlling capillary aggregation and thrombus. Results are compared with available experimental results.