The Effect Of Transplanted Bone Marrow Stromal Cells On Repairing Of Hemopoietic Injury In Exposed Mice

In 1968, Friedenstein found that in the marrow there were not only hemopoietic cells which suspended to grow but also some fiber-like cells which adhered to grow. The latter ones were similar to fibroblasts in shape, but they can differentiate to bone-like or cartilage-like colonies, so he called these cells Marrow Stromal Cells (MSC). Researches indicated that in different inductions, MSC can differentiate to many kinds of cells such as bone, cartilage, tendon, muscle, fat, neuron and so on. Thus, MSC has become the ideal target cells for tissue engineering, cell and gene therapy. Acute radiation hemopoiesis injury refers to the injury of hemopoiesis system which is caused by large dose of radiation in a short time. Such serious radiation can destroy the DNA structure directly or indirectly, and then causes injuries in many systems, such as hemopoiesis system, nervous system, dermal system and so on. Acute radiation injures the hemopoiesis system most severely. After radiation, the amount of hemopoiesis cells in lymphoid node, spleen and marrow decrease sharply. The insufficiency of White Blood Cel(lWBC) and Red Blood Cel(lRBC)can cause many clinical symptoms like bleeding and infection. Meanwhile, acute radiation also injures the hemopoiesis stromal cells and causes severe damage of hemopoietic microenvironment. With the decrease of hemopoiesis cells and the damage of hemopoietic microenvironment, hemopoiesis injury can not be repaired promptly. Research found that MSC is of great importance in the process of recovery after severe radiation hemopoiesis injury, for it promotes Hemopoiesis Stem Cell (HSC) to locate in the injury places quickly. Besides, the extracellular matrix and cytokine offered by MSC can also promote the proliferation and differentiation of HSC, and then participate the repair of hemopoiesis injury.Our experiments studied the hemopoiesis effect of allogeneil graft of Marrow Stromal Cell (MSC)on radiation injured Mice, observed the distribution of Marrow Stromal Cell (MSC) which were marked with fluorescence agent Hoechst33342 in vitro and then transplanted into acute radiated mice, and revealed the hemopoietic reconstitution in allogeneic MSC transplantation.1. Culture MSC in vitro, transplant MSC to radiated BALB/c mice via intravenous injection. The White Blood Cell(WBC), Red Blood Cell(RBC), Platelet(PLT), Hemoglobin(HGB)and Colony Forming Unit (CFU-S)were observed after MSC transplantation. Result: the WBC, RBC, PLT and HGB of the transplant-group are significantly higher than those of the radiated -group(WBC,PLT,HGB:P<0.01;RBC :P<0.05), the CFU-S of the transplant-group is also higher than that of radiated-group(P<0.01).2. Separate the femoral bones of mice, douche out the bone marrow with DMEM, gather the cell suspension and centrifuge them twice, then culture MSC in vitro, mark the MSC with Hoechst33342 at final concentration of 10μg/ml. 30 minutes later, gather the MSC and transplant them into radiated mice via intravenous injection, each mouse was injected with 2×105 MSC. Observe whether the marked MSC distribute in the hearts, livers, spleens, lungs and kidneys of radiated mice or not at time points of 1w, 2w and 3w after MSC transplantation. Results: After being marked with Hoechst33342, the nuceluses of MSC were in bright blue light. All mice of MSC-transplant-group survived until execution, but three mice of Non-MSC-transplant-group died during the three weeks; and few of marked MSC were found in hearts, livers, lungs and kidneys in the frozen section at each time point, but a huge number of marked MSC were found on the surface of spleens. And at 9th day, spleen colonies formed.Our experiments show that allogeneil graft of Marrow Stromal Cell can induce hemopoietis stem cell to locate in the spleen and form colonies, can significantly increase the peripheral blood cells, and promote the early hemopoietic reconstitution after radiation injury. Additionally, transplanted MSC can not only live inside the radiated mice, but also specially immigrate to the injured site, and participate the reconstitution of hemopoiesis after acute radiation injury.