Selective expansion of normal haemopoietic progenitors from chronic myelogenous leukaemia marrow |
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Authors: | Miriam Fogli,Marilina Amabile,Giovanni Martinelli,Alessandra Fortuna,Damiano Rondelli,Marina Ratta,Antonio Curti,Sante Tura,& Roberto M. Lemoli |
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Affiliation: | Institute of Haematology and Medical Oncology 'Seràgnoli', University of Bologna, Bologna, Italy |
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Abstract: | CD34+ and CD34+ DR? cells from the bone marrow (BM) of chronic-phase chronic myelogenous leukaemia (CML) patients at diagnosis were tested for their colony-forming ability in response to early and intermediate-late colony stimulating factors (CSFs). Molecular analysis revealed that 55.6 ± 9% SD of CD34+DR? colonies, in which actin and ABL mRNA were detectable, expressed the product of the BCR-ABL gene. The percentage and the clonogenic efficiency of CML DR? cells were significantly lower than those of comparable DR? cells from normal donors. However, clonogenic assays using recombinant human CSFs demonstrated a remarkable proliferation of CML cells when stimulated by SCF, IL-11 and IL-3, used as single factors in the presence of erythropoietin (EPO) and was almost entirely due to erythroid progenitors. Conversely, optimal stimulation of CD34+DR? cells from normal donors required co-incubation with three or more CSFs. Stroma-noncontact long-term cultures were then established in the presence of exogenous CSFs and human irradiated allogeneic stromal layers or the murine stromal cell line M2-10B4, engineered to produce G-CSF and IL-3. In these cultures the combination of SCF and IL-3 induced a 25.4 ± 5 SD, 40 ± 6 SD and 20.5 ± 6 SD fold increase of colony-forming unit cells (CFU-C), at weeks 2, 4 and 5, respectively. At the same time-points the number of primitive long-term culture initiating cells (LTC-IC) showed a 4 ± 2 SD, 3.3 ± 1.5 SD and 2.3 ± 1 SD fold increase compared to baseline values. BCR-ABL mRNA analysis of single colonies demonstrated that 27 ± 9% SD and 7 ± 3% SD CFU-C at weeks 4 and 5, respectively, expressed the fusion gene, whereas leukaemic LTC-IC disappeared from the culture by week 2. These results suggest that leukaemic CD34+DR? cells have a different pattern of response to CSFs than normal cells. In addition, we established culture conditions which allow selective expansion of benign haemopoietic cells coexisting with leukaemic progenitors. |
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Keywords: | chronic myelogenous leukaemia stem cells normal progenitors ex-vivo expansion CSFs |
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