Feasibility and limits of bone marrow mononuclear cell expansion following irradiation

Purpose: To define the ability of bone marrow mononuclear cells (BMMNC) to expand after irradiation and to determine the amount of apoptosis in irradiated expanded cells. Materials and methods: Non-human primate BMMNC were irradiated in vitro at doses ranging from 0 to 4 Gy and were cultured during 1 week in the presence of interleukin 3, interleukin 6, stem cell factor, thrombopoietin and fms-like tyrosine kinase-3 ligand. The expansion yield of BMMNC, colony-forming cells and CD34+ cells were compared with non-irradiated control cultures. Apoptosis in expanded cells was also defined by annexin V/propidium iodine staining. Results: Irradiation of BMMNC up to 1 Gy did not modify the ability of haematopoietic cells to expand. At higher doses, expansion of haematopoietic cells is reduced as compared with non-irradiated cultures but it remains significant. This reduction in expansion of BMMNC was related to radiation-induced apoptosis. Conclusion: The results suggest that it is possible to expand haematopoietic cells after irradiation doses at least up to 2 Gy. This suggests a possible use of cell therapy for the treatment of radiation accident victims.