Future of platelet transfusion therapy. (A) Because of numerous concerns about donor-derived platelets, stem cell–derived platelets may be a potential source for transfusion. (B) Instead of generating platelets from human embryonic or induced pluripotent stem cells ex vivo, Wang et al demonstrated that ex vivo–derived human megakaryocytes infused into mice can release functional platelets into the circulation. Professional illustration by Luk Cox, Somersault18:24.