Recombinant human IGF-1 has been successfully used to treat them. This protein is released into the blood where it serves as the precursor for angiotensin . How angiotensin is manufactured, and the role it plays in maintaining blood pressure is described in the discussion of the kidney hormone renin . Thrombopoietin is a protein of 332 amino acids. It stimulates precursor cells in the bone marrow to differentiate into megakaryocytes .
Megakaryocytes generate platelets , essential to blood clotting .
A segment of thrombopoietin, manufactured by recombinant DNA technology , is now available for human therapy. It already shows promise in quickly restoring normal platelet counts in patients who have undergone chemotherapy.