Thrombopoietin: the primary regulator of platelet production.

Although the term thrombopoietin was first used nearly 40 years ago to describe the humoral regulator of platelet production, doubts surrounding its existence remained until the molecule was cloned 3 years ago. Using the recombinant protein, several investigators have shown that thrombopoietin influences all aspects of megakaryocyte development, from the hematopoietic stem cell to the mature platelet. The present review focuses on the discovery and characterization of this hormone, the initial stages of its clinical development, and some important yet unanswered questions of its molecular and cellular physiology. (Trends Endocrinol Metab 1997;8:45-50). (c) 1997, Elsevier Science Inc.