Differences in megakaryocyte expansion potential between CD34(+) stem cells derived from cord blood, peripheral blood, and bone marrow from adults and children

Objective. Reinfusion of ex vivo expanded autologous megakaryocytes togethe r with stem cell transplantation may be useful to prevent or reduce the per iod of chemotherapy-induced thrombocytopenia. We compared the megakaryocyte expansion potential of CD34(+) stem cells derived from different sources: cord blood (CB), peripheral blood (PB), bone marrow from adults (ABM), and bone marrow from children (ChBM), Three different growth factor combination s were tested to identify the best combination for each of the sources. Materials and Methods. CD34(+) cells were isolated from CB, PB, ABM, or ChB M and cultured in an in vitro liquid culture system in the presence of thro mbopoietin (Tpo), Tpo + interleukin (IL-1), or Tpo + IL-3, After 8 days, pr oliferation was determined and the cultured cells were identified with line age-specific surface markers by flow cytometry, Results. Cultures with ChBM-derived CD34(+) cells showed the lowest Level o f expansion of megakaryocytes and gave rise to more profound formation of m yeloid and monocytic cells. In cultures with BM- or PB-derived cells, prese nce of IL-3 reduced the number of immature megakaryocytes (CD34(+)CD41(+) c ells). However, in CB cultures, the number of CD34(+)CD41(+) cells was high est in cultures with Tpo + IL-3. Overall, cultures with CB CD34(+) cells yi elded the highest number of megakaryocytes, but these cells showed reduced ploidization and lower level of CD41 expression, suggesting less maturation . Conclusions. Each of the different CD34(+) cell sources responded different ly to cytokine stimulation, For PB and ABM, the cytokine combination Tpo IL-I is most suitable to obtain high numbers of both immature and mature me gakaryocytes for transfusion purposes. For CB, Tpo + IL-3 is better. (C) 20 00 International Society for Experimental Hematology, Published by Elsevier Science Inc.