Host: The Japan Radiation Research Society
Co-host: City of Kitakyushu, University of Occupational and Environmental Health, Japan
Placental/umbilical cord blood-derived mesenchymal stem cell-like stromal cells were applied to a regenerative ex vivo expansion of X-irradiated human CD34+ cells in a serum-free liquid culture supplemented with a combination of interleukine-3 plus stem cell factor plus thrombopoietin. The total number of cells and of lineage-committed myeloid hematopoietic progenitor cells generated in the co-culture of both non-irradiated and X-irradiated cells with stromal cells was significantly higher than those in the stroma-free culture. In addition, the number of CD34+ cells and CD34+/CD38- cells, immature hematopoietic stem/progenitor cells also increased more than the stroma-free culture. The stromal cells produced various types of cytokines, although there was little difference between the co-cultures of non-irradiated and X-irradiated cells with stromal cells. Furthermore, when X-irradiated cells came in contact with stromal cells for 16 hr before cytokine stimulation, a similar degree of hematopoiesis obtained in the results of non-irradiated cells stroma-free culture was observed, thus suggesting the critical role of cell-to-cell interaction. Since the efficient expansion of stem cells derived from radiation casualties provides a suitable cell source for autologous cell therapy, the present results showed the efficacy of human CB-derived mesenchymal stem cell-like stromal cells for the regenerative expansion of hematopoietic stem/progenitor cells exposed to irradiation.
