Thrombopoietin: its role in platelet disorders and as a new drug in clinical medicine

The cloning and characterization of thrombopoietin and its receptor Mpl in the past few years has been a major advance in haematology. It opens new wa ys of studying congenital and acquired platelet disorders, leading to new i nsights in the pathogenesis and treatment of this group of diseases. The Tpo level of the blood appears to be a useful marker for the differenti ation between thrombocytopenia due to peripheral destruction and that due t o thrombocytopoietic failure. No simple clinical parameter exist for this i mportant differential diagnostic problem. When recombinant thrombopoietin becomes available for therapy it will rapid ly become the drug of choice for many of our patients. However, because of all the legal and commercial issues at stake it is expected that it will st ill take a few more years before general availability is realized. Short pe ptides with Tpo activity (Cwirla et al, 1997; Kimura et al, 1997), which ca n be synthesized chemically, may form a more easily obtainable alternative.