Expanded Impacts of Platelet Functions: Beyond Hemostasis and Thrombosis

Platelets are very small (2 μm) anucleate hematologic effector cells [1] with a lifespan of approximately 8–10 days [2]. Platelets are traditionally well known for their primary functions in thrombosis and hemostasis [3]. The hemostasis function was first identified by Osler in 1873, who described platelets as a “blood plaque” in the white thrombus [1]. In physiologic states, platelets are not accessible to subendothelial structures such as collagen fibers or von-Willebrand factor [4]. However, when the vessel wall is injured, the subendothelial structures are exposed, resulting in the initiation of platelet adhesion [3,4]. This interaction consequently triggers signal cascades in platelets to seal the thrombus leak at the site of vascular injury [4]. Thus, platelets have long been simply regarded as the main components of bleeding control [3,4]. In addition to this primary role of preventing blood loss from an injured vessel, the thrombus prevents the dissemination of foreign pathogens into the organism [4]