Platelet Heterogeneity in Aging and Cancer: A Single-cell Atlas Reveals Subtype-specific Roles in Metastasis

Background Platelets are increasingly recognized as versatile regulators of aging, immunity, and cancer, yet their functional heterogeneity has remained poorly defined. Methods We performed the first large-scale single-cell RNA sequencing of 28,192 platelets from healthy, aged, metastatic, and treated mice, using the BD Rhapsody platform. Results Our analysis reveals four conserved and functionally distinct platelet subtypes: hemostatic platelet (HP), immunothrombotic platelet (ITP), neuron-like platelet (NLP), and platelet-erythrocyte aggregate (PEA). Among these, a the Tpm2- high HP subcluster drove aging-associated lung metastasis via cytoskeletal remodeling. The ITP subtype served as a signaling hub for immunothrombosis, with an ITP-Bridge subpopulation coordinating immune-adherent platelets via Ppbp-Cxcl2 and the Thbs1-Cd47 checkpoint axes. Strikingly, AAV-mediated m Pf4 gene therapy redirected the NLP subtype from a pro-thrombotic phenotype toward a neuron-like state, mitigating age-related functional decline. Conclusions This study provides the first comprehensive roadmap of platelet heterogeneity, linking subtypes to aging and metastasis, and proposing PF4 -based intervention and cytoskeletal targets for diagnosis and therapy.