Platelet generation in vivo and in vitro

Platelets play crucial roles in hemostasis, thrombosis, and immunity, but our understanding of their complex biogenesis (thrombopoiesis) is currently incomplete. Deeper insight into the mechanisms of platelet biogenesis inside and outside the body is fundamental for managing hematological disorders as well as development of novel cell-based therapies. Here we address current understanding of in vivo thrombopoiesis, including mechanisms of platelet generation from megakaryocytes (proplatelet formation, cytoplasmic fragmentation and membrane budding) and their physiological location. Progress has been made replicating these processes in vitro for potential therapeutic application, notably in platelet transfusion and bioengineering of platelets for novel targeted therapies. Current platelet-generating systems and their limitations, particularly yield, scalability, and functionality, are discussed. Finally, we highlight current controversies and challenges in the field that need to be addressed to achieve full understanding of these processes, in vivo and in vitro.