As a major contributor to cardiac diseases, thrombosis, a pathological process in which the formation of a blood clot restricts blood flow, is a leading cause of mortality worldwide. A central event in thrombosis involves thrombin-mediated cleavage of soluble fibrinogen into fibrin monomers, which polymerize into an insoluble fibrin mesh that forms the thrombus. While the risk of thrombosis increases markedly with age, the underlying cellular mechanisms linking aging and thrombus formation remain incompletely understood. Here, we identify a potential mechanism whereby cellular senescence in cardiac cells exacerbates thrombus formation via increased thrombin generation and impairs fibrinolysis, together promoting a pro-thrombotic state. We examined the pro-thrombotic phenotype of doxorubicin-induced senescence of human cardiac fibroblasts and cardiac endothelial cells. In both cell types, senescence accelerated and amplified fibrinogen polymerization. Treatment with a thrombin inhibitor reduced this polymerization and the cleavage of a thrombin-specific substrate by senescent cells, implicating thrombin as a key mediator of their pro-thrombotic phenotype. Complementary to their procoagulant effects, senescent cells also impaired thrombus resolution by suppressing plasminogen activation and downstream fibrinolysis. Gene expression analysis revealed senescence-associated upregulation of procoagulant and antifibrinolytic mediators, consistent with the observed functional effects. Finally, we show that the senescence-mediated polymerization of fibrinogen is dose dependent and attenuated by the senostatic agent, rapamycin. Collectively, these findings establish a direct mechanistic link between cellular senescence and thrombosis in cardiac cells, highlighting senescence as a potential therapeutic target in age-related thrombotic disease.
