Physiology and preclinical studies of thrombopoietin.

Until recently, the molecular basis for the control of platelet production was largely unknown. In the past year, several groups have obtained complementary DNA for thrombopoietin, the substance first theorized nearly 40 years ago to regulate this process. Cellular and molecular studies have confirmed many of the properties previously attributed to this molecule, and have revealed some surprises. It is now clear that thrombopoietin is the critical regulator of platelet production. Detailed study of the molecule will likely yield important physiologic insights into megakaryocyte biology, and its application to states of iatrogenic and natural marrow failure will almost certainly provide therapeutic advances.