Confining thrombus morphospace through targeted inhibition of platelet mechanosensory signaling.

Abstract

BACKGROUND: While current antiplatelets protect against thrombosis, their clinical utility is limited by an elevated risk of bleeding. OBJECTIVES: To understand how structure-function relations in the hemostatic system may be leveraged into improve risk/benefit ratios of antiplatelet therapies. METHODS: We developed a deep learning-based framework to track the activities of large numbers of platelets in vivo, enabling a detailed comparative assessment of the effects of therapeutic interventions on the evolving structural hierarchy of the hemostatic response. RESULTS: Unlike conventional antiplatelets targeting paracrine signaling, selective pharmaceutical inhibition of platelet mechanosensory signaling via PI3KC2α preserved the initial build-up of thrombi following vascular injury to high-flow mesenteric veins. However, as this burst of hemostatic activity subsided, inhibition of platelet mechanosensory signaling caused localized reductions of platelet intracellular calcium ion levels ([Ca]) in shear-exposed peripheral thrombus subregions, inhibiting the formation of platelet clusters capable of withstanding the drag forces of the blood flow. As a consequence, platelets in these subregions detached, became elongated, and/or slid along the thrombus surface. On a macrostructural level, this selective destabilization prevented sustained physical expansion of thrombi outside the perimeters of vascular injuries while preserving platelet packing density in thrombus subregions close to vascular injuries. CONCLUSION: Collectively, our results highlight platelet mechanosensory signaling as a significant driver of sustained platelet population growth after the initial agonist-driven phase of thrombus expansion. We show that pharmaceutical targeting of this pathway enforced the convergence of thrombus growth trajectories toward a rheologically favorable setpoint without compromising the structural integrity of thrombus subregions that are critical for hemostasis.