Ex vivo expansion of megakaryocytic cells

The use of platelet transfusion to ensure the recovery of thrombopoiesis in patients constitutes high-cost support. The identification and cloning of recombinant human thrombopoietin (TPO) and the development of efficient met hods of purification of hematopoietic stem cells and progenitor cells have ameliorated the development of strategies of ex vivo expansion of megakaryo cyte (MK) progenitor cells and mature MKs. Synergistic combinations of cyto kines including TPO, interleukin (IL)-1, IL-3, IL-11, stem cell factor, and FLT-3 ligand induce the ex vivo expansion of colony-forming unit-MK progen itors and MKs from cytokine-mobilized peripheral blood cells, bone marrow a nd cord blood CD34(+) cells. Depending on the various culture conditions, i e, combinations of growth factors, initial concentration of CD34+, serum or serum-free cultures, and/or oxygen tensions, the expansion-fold of MKs and their progenitor cells vary greatly. The clinical applications of the rein fusion of ex vivo-generated MK cells have been investigated successfully in cancer patients following high-dose chemotherapy. This review reports the latest information concerning ex vivo expansion of MKs and the current stat us of clinical trials. Int J Hematol. 2000;71:203-210 (C) 2000 The Japanese Society of Hematology.