Are there more tricks in the bag for treating thrombocytopenia?

Abstract

Thrombocytopenia, an abnormally low number of circulating platelets, results from inadequate platelet production, splenic platelet sequestration, or accelerated platelet clearance. Platelet transfusions are now the cornerstone for treating thrombocytopenia. With an ever-expanding demand for platelets, and with many patients having an inadequate response to platelet transfusions, new strategies are needed to treat thrombocytopenia. In this issue of the JCI, Fuentes et al. present provocative data regarding the use of direct megakaryocyte infusions as a novel approach to manage this vexing clinical problem.

Figure 1. Megakaryocytopoiesis and platelet production.

(A) A model for megakaryocytopoiesis demonstrates the progressive increase in size as megakaryocytes mature in the marrow, with mature megakaryocytes developing cytoplasmic projections called proplatelets. Platelet release occurs from the ends of proplatelet projections, with at least some platelet release occurring directly in the marrow circulation from proplatelet projections that extrude through the marrow’s fenestrated vasculature. (B) Fuentes et al. (19) have demonstrated that infused mature megakaryocytes release platelets into the circulation, thereby increasing circulating platelet counts, and that these platelets contribute to hemostasis at the site of vascular injury.