Thrombopoietin Level and Bone Marrow Megakaryocyte Colony Formation in Various Diseases with Thrombocytopenia

Cho, Jin Sun; Choe, Byung Kyu; Cho, Yoon Jung; Kim, Heung Sik; Kang, Chin Moo

Abstract

PURPOSE: Thrombocytopenia is a serious life threatening consequence in patients with bone marrow failure syndrome. Thrombopoietin (TPO), recently cloned by several groups has been shown to be a key regulation of megakaryopoiesis and thrombopoiesis. Recent studies have demonstrated a positive or negative relationship between TPO levels and platelet counts due to underlying disease states. To clarify the role of TPO in thrombocytopenic condition we determined plasma TPO levels and megakaryocyte colony assay. METHPDS: TPO levels were measured in thrombocytopenic patient with aplastic anemia, chemotherapy induced bone marrow failure, idiopathic thrombocytopenic purpura (ITP) and in newborn by ELISA (QuantikineTM, R&D System, USA). Controls were short statured normal children with normal platelet counts. Plasma was preserved in 20oC until test. CFU-mega was determined by MegaCultTM (Stem Cell Tech. Inc., Canada). Ficoll separated mononuclear cells were cultured for 10~12 days with TPO or stem cell factor (SCF) in 37degrees C 5% CO2 atmosphere, colonies were fixed, stained and examined with inverted microscope. Results were analysed by Student-t test.
RESULTS
TPO levels were markedly increased in aplastic anemia and chemotherapy induced thrombocytopenia compared to those of normal controls. Patients with ITP had decreased level of plasma TPO. There was inverse relationship between platelet count and TPO levels for patients with aplastic anemia and chemotherapy induced thrombocytopenia. There was no definite relationship between platelet counts and TPO levels but inverse relationship between platelet counts and PDW levels in neonates was noted. The levels of TPO were increased after improvement of platelet in thrombocytopenic neonate. Megakaryocyte colonies were increased in the mononuclear cells of the patients with ITP and chemotherapy induced thrombocytopenia. There was little colony formation in aplastic anemia. TPO had no definite effect in megakaryocyte colony formation but SCF increased colony formation.
CONCLUSION
TPO levels were increased in aplastic anemia and chemotherapy induced thrombocytopenia but decreased in ITP. There was inverse relationship between platelet count and TPO levels in aplastic anemia and chemotherapy induced thrombocytopenia. Thus TPO could be useful for differentiate the etiology of thrombocytopenia. Megakaryocyte colony was increased in ITP and chemotherapy induced thrombocytopenia, but decreased in aplastic anemia. SCF was effective in megakaryocyte colony formation. TPO and SCF will be helpful to increase platelet in thrombocytopenic patients. However, further study will be needed.