ABSTRACTThe CD34 antigen is present at all differentiation stages of hematopoietic cells, from immature progenitor cells to committed precursor cells. In vivo, transplantation of CD34+ cells is sufficient to allow hematopoietic recovery after myeloablative chemotherapy, but a neutropenic period of 9–12 days still exists, even when hematopoietic growth factors are given posttransplantation. After ex vivo expansion cultures in the presence of cytokines, CD34+ cells can generate mature precursor cells in a stroma-free liquid culture system. This could lead to a shortening of the aplasia duration, but the persistence of primitive progenitor cells in the expanded CD34+ compartment remains to be demonstrated. In this study, CD34+ cells were isolated from eight peripheral blood (PB) and eight cord blood (CB) samples using either Isolex™ 50 (n= 6), Ceprate™ LC CD34 kit (n= 6), or Microcellector™ T-25 Stem Cell kit (n= 4). We have evaluated the functional potential of CD34+ cells after 7 days of ex vivo expansion culture in the presence of 500 UI/ml of interleukin-1 (IL-1), 10 ng/ml of IL-3, and 10 ng/ml of stem cell factor (SCF). The expansions of nucleated cells, granulocyte-macrophage colony-stimulating factor (GM-CSF)-responsive committed precursors, IL-1 + IL-3 + SCF + erythropoietin (EPO)-responsive multilineage progenitors, and 5-fluorouracil (5-FU)-resistant quiescent progenitor were 8-fold, 59-fold, 4.4-fold, and 2.2-fold, respectively. There was no significant difference in the amplification/expansion parameters between cultures initiated with CD34+ cells from PBSC or CB. Our data confirm that cytokine-mediated ex vivo expansion of blood CD34+ cells can produce large numbers of committed precursors and does not significantly affect the compartment containing more immature progenitors. Cytokine-mediated expansion could be of great interest in autologous transplantation to decrease the duration of marrow
展开▼
