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Reinjection of ex vivo expanded non-human primate bone marrow mononucleated cells (BMMNC) strongly reduces radiation-induced aplasia


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Jean Marc Bertho, Johanna Frick, Christelle Demarquay, Alain Chapel, Nicolas Dudoignon, François Trompier, Jocelyne Aigueperse, Dominique Thierry 31st Annual Meeting of "International Society for experimental haematology" - Montreal,Canada, 5-9 juillet 2002.

Résumé

Ex vivo expansion of hematopoietic cells is a promising approach for the treatment of pan-cytopenia. Numerous protocols have been studied, most of them starting from purified CD34+ hematopoietic cells. However, the ex vivo expansion of total BMMNC may present some advantages. BMMNC contain all differentiation stages present in the bone marrow, including precursor cells able to generate rapidly mature circulating cells, but also immature cells, able to ensure a long-term hematopoietic recovery. Moreover, BMMNC also contain accessory cells, including mesenchymal stem cells, which can sustain hematopoietic recovery. In order to assess the therapeutic efficacy of ex vivo expanded BMMNC, we have set up a non-human primate model. Two ex vivo expansion protocols for BMMNC were studied. The first consisted of a 7-day culture in the presence of SCF, Flt3-ligand, TPO, IL-3 and IL-6, which induced preferentially the expansion of immature hematopoietic cells (3.1±1.4, 10.0±5.1, 2.2±1.9 and 1.0±0.3 fold expansion for MNC, CFU-GM, BFU-E and LTC-IC respectively). The second was with the same cytokine combination supplemented with G-CSF with an increased duration of culture up to 14 days and induced mainly the production of mature hematopoietic cells (17.2±11.7 fold expansion for MNC and no detectable BFU-E and LTC-IC) although expansion of CFU-GM (13.7±18.8 fold) and CD34+ cells (5.2±1.4 fold) was also observed. Results showed the presence of mesenchymal stem cells and cells from the lymphoid and the megakaryocytic lineages in 7 day expanded BMMNC. To test the ability of ex vivo expanded cells to sustain hematopoietic recovery after radiation-induced aplasia, 6 non-human primates were irradiated at a supra lethal dose of 8 Gy and received the product of either 7 day (24 hours after irradiation) or 14 day (8 days after irradiation) expanded BMMNC. Results showed that the 7 day ex vivo expanded BMMNC shortened the period and the severity of pan cytopenia and improved hematopoietic recovery, while the 14 day ex vivo expanded BMMNC mainly produced a transfusion-like effect during 8 days, followed by hematopoietic recovery. These results suggest that ex vivo expanded BMMNC during 7 days may be highly efficient in the treatment of radiation-induced aplasia.