Platelets are crucial players in hemostasis and thrombosis, but also contribute to immune regulation and host defense, using different receptors, signaling pathways and effector functions, respectively. Whether distinct subsets of platelets specialize in these diverse tasks is insufficiently understood. Here, we employed an in vivo pulse-labelling method in Mus musculus models for tracking in vivo platelet ageing and its functional implications. Using in vitro and in vivo assays, we reveal …