Platelet thrombus formation by upstream activation and downstream adhesion of platelets in a microfluidic system

Platelet activation causes platelet aggregation and their adhesion to the vascular wall. In the circulatory environment, platelet activation and adhesion might not occur at the same site. In this study, we developed a microfluidic platform to examine platelet adhesion and aggregation under pathophysiological shear flow. Upstream platelet activation was conducted either using agonists or by shear flow, whereas downstream platelet adhesion was induced using collagen-coated microbeads packed in a tube. Adopting microbeads, activated platelets led to rapid occlusion and blood flow arrest. The degree of platelet adhesion and aggregation was monitored by measuring the blood migration distance, allowing a flow-through in the microchannel until it was blocked. Downstream platelet adhesion was strongly dependent on the upstream activation parameters including shear rate ranges between 754 and 2400 s^-1, shearing time greater than 10 s, and incubation time greater than 20 s. Furthermore, through the integration of various leading-edge technical elements, the present system produced comprehensive real-time results of platelet-associated thrombus formation. Thus, this disposable device might help examine platelet dysfunction for preoperative patients and antiplatelet therapy in the clinic.