Platelet-endothelial crosstalk drives distinct endothelial dysfunction in bicuspid aortic valve disease

Background: Bicuspid aortic valves (BAV) predispose individuals to premature development of aortic stenosis (AS). The abnormal hemodynamic environment of BAV affects both platelets and valvular endothelial cells (VECs), but whether platelet-derived signals contribute to valve morphology-specific endothelial dysfunction remains unknown. Methods: Platelets and VECs were obtained from patients with BAVs or tricuspid aortic valves (TAVs) undergoing valve replacement for AS. Platelets were activated to generate platelet releasate (PR). PR composition and its effects on VECs were investigated using complementary molecular, multi-omic, functional, and computational approaches. Results: BAV and TAV patients exhibited markedly distinct PR profiles, which translated into differential endothelial responses. Strikingly, BAV-derived PR elicited a substantially more pronounced endothelial dysfunction phenotype, characterized by widespread molecular reprogramming and functional alterations. Integrated multi-omics uncovered mitochondrial dysfunction as a central feature of BAV PR-induced endothelial injury, accompanied by activation of pathways spanning endothelial remodeling, migration, and immune-cell recruitment. These molecular signatures translated into mitochondrial depolarization, altered mitochondrial dynamics, enhanced VEC migration, and increased neutrophil adhesion and chemotaxis. Finally, computational ligand-receptor and ligand-target analyses identified candidate signaling axes linking platelet-derived mediators to endothelial reprogramming, highlighting potential therapeutic targets. Conclusions: We provide the first direct evidence that platelet activation contributes to AS initiation through the induction of endothelial dysfunction and that these effects are amplified in BAV. These findings identify platelet-VEC crosstalk as a previously unrecognized mechanism linking abnormal valve hemodynamics to disease onset. Targeting platelet-derived mediators may represent a novel therapeutic strategy for AS, specifically in BAV.