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 improved risk/benefit ratios for 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 (iPMS) 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, iPMS caused localized reductions of platelet [Ca²⁺]_i 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 slided 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.

Conclusions: 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 towards a rheologically favourable setpoint, without compromising the structural integrity of thrombus subregions that are critical for hemostasis.