OBJECTIVETo explore the hematopoietic reconstitution potential of mesenchymal derived stem like cells.

METHODSWe transplanted bone marrow mesenchymal derived stem like cells into lethally irradiated BALB/c mice. Hematopoietic cells were derived from the non-adherent bone marrow cells 24 hours after initial culture while murine mesenchymal derived stem like cells from bone marrow of donor mice were cultured for 10 days before the transplantation.

RESULTSAll mice of group 1 and 3 died in 7-8 days post irradiation following transplantation, while all the mice from group 2 and 4 survived. The time course of hematopoietic reconstitution was then observed. The peripheral blood and bone marrow cell count recovered in the MSC + G-CSF transplanted group and the BM transplanted group after 3 weeks. Interestingly, CFU-GM number in the MSC + G-CSF transplanted group increased significantly after 2 weeks and even more than that in the BM transplanted group after 3 weeks while as CFU-GM colony dropped 2 weeks after in the BM transplanted group. Spleen colony (CFU-S) number and size of the MSC + G-CSF transplanted group was significantly greater than the BM transplanted group. Furthermore, PCR analysis was performed using peripheral blood cells to determine if any male-derived cells were present. No male-derived cells were found in any of the mice from group 1 and 3. Y-chromosome-specific src gene was found to be dominant in the MSC + G-CSF transplanted group and the BM transplanted group by week 4 post transplantation. In addition, we demonstrated that induction with G-CSF lead to CFU-GM colony formation from MSC compartment in vitro.

CONCLUSIONThese results indicate that under stimulation of G-CSF, mesenchymal derived stem like cells might differentiate into hematopoietic primitive stem cells in vivo and have the capacity to re-establish hematopoiesis in lethally irradiated mice. This study should provide an alternative transplantation treatment for malignancy.