Inhibiting biomechanical platelet aggregation to prevent arterial thrombosis without compromising hemostasis

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Project Summary/Abstract Arterial thrombosis, which describes the formation of abnormal blood clots in the artery, is a highly fatal disease that claims ~500,000 American lives per year. A symbolic feature of arterial thrombosis is the elevated shear rate and shear force generated by stenosis, which facilitates platelet aggregation towards vessel occlusion. Unfortunately, current therapeutic strategies are ineffective in inhibiting the prothrombotic effects of the pathological blood flow, and have a major risk of excessive bleeding. The overall objective of this proposal is to establish a mechanism-driven strategy to better treat arterial thrombosis. Our lab's previous works and my research identified that the prothrombotic effects of pathological blood flow result from a phenomenon called “biomechanical platelet aggregation”, in which mechanical force drives platelets to crosslink. Von Willebrand factor (VWF) is a plasma protein that mediates platelet crosslinking by binding to platelet receptor GPIbα. In my preliminary study, I worked on an artificially designed triple-residue VWF mutation named `M13', which inhibited VWF in mediating biomechanical platelet aggregation and shear-induced thrombogenesis, but did not affect platelet adhesion or hemostasis. Based on these findings, I hypothesize that: biomechanical platelet aggregation is a key factor to arterial thrombosis, and its inhibition can suppress arterial thrombosis without compromising hemostasis. I propose 4 aims to step-by-step establish anti-thrombotic approaches targeting the biomechanical platelet aggregation. Aim 1 will combine biomechanics and hematology assays to study the mechanism underlying M13's function in inhibiting biomechanical platelet aggregation but not adhesion. Aim 2 will establish a microfluidic-based assay that concurrently assesses platelet adhesion and shear-induced thrombogenesis, which allows the screening of anti-thrombotics targeting biomechanical platelet aggregation. In Aim 3, a monoclonal antibody against VWF, NMC4, was identified to be functionally aligned with my anti-thrombotic strategy. I will collaborate with my postdoctoral lab and use NMC4 as a prototype to design and produce anti-thrombotic agents. A 3-step screening procedure will be established to select candidate agents with the best functional performance. Lastly in Aim 4, I will expand my anti-thrombotic strategy to another platelet receptor also important to biomechanical platelet aggregation: integrin αIIbβ3. I will explore the efficacy and safety of inhibiting both VWF- and αIIbβ3-mediated biomechanical platelet aggregation in treating arterial thrombosis exacerbated by diabetes. Overall, this research will be accomplished in the setting of a comprehensive career development program designed to help me achieve my career goal as an independent researcher in the interdisciplinary field of vascular biology, mechanobiology and bioengineering. During the K99 phase, I will continue to gain expertise in biochemical, preclinical and translational approaches. My mentor, collaborators and consultants will together guide me in the steps towards successful transition to independence over the course of the award period.