Bone Marrow Mesenchymal Stem Cells In Combination With H-2 Haploidentical Bone Marrow Transplantation For Treatment Of Acute Radiation Sickness In Mice Experimental Research

The severe bone marrow type of acute radiation syndrome (ARS) is paroxysmal, rapidly aggravated, and short-term died demerits. That of the myelosuppression, immune suppression and multiple organ injuries are the most important lethal factors. The hematopoietic stem cells transplantation (HSCT) is the crucial measure for the ARS. The HLA haplotype matched HSCT (haplo-SCT) is as to a management when shortage identical HLA donor. But haplo-SCT has many demerits such as slow haematopoiesis recovery, immune suppression, conditioning and GVHD complication increasing mortality. Mesenchymal stem cells (MSCs) are adherent cells capable of self renewal and multilineage differentiation, improving hematopoiesis and immunomodulation. So the HSCT with MSCs infusion maybe a optimal management for the svere bone marrow type of ARS.In our experiments, the cultural method of MSCs of mice was reformed with percollgradient separation, adherent culture, optimized cells culture fluid and serum, and replace midium procedure. Peripheral blood cells counts, apoptosis, cell cycle, GM-CFU and F-CFU of bone marrow cells and pathologic variety of medulla were observed in mice with MSCs treatment after sublethal dose of total body irradiation(TBI). We studied the mechanisms of MSCs enhancing the hematopoiesis in bone marrow from above results. We found MSCs reduced p53 protein expressing by immunohistochemistry, reduced cell apoptosis, accelerated cells cycle switching, enhanced the recovery of tissue radiation injuries of thymus, spleen and bone marrow of sublethal dosage radiation mice, thus protected the radiated mice.MSCs improved peripheral blood cells recovery, especially increased thrombopoiesis in bone marrows, decurtated myelosurppression stage, reduced infection and hemorrage complications, extended the survival time of mice with H-2 haploid matched bone marrow tansplantation(haplo-BMT) after 8Gy TBI. MSCs also had therapeutic effects to mice after 10Gy TBI by survival experiments. And the safe as well as effective dosages of MSCs were selected by three dosages of MSCs treating experiments. The sry-gene chimerism of bone marrows, spleen and thymus of the receiptor, T-lymphocyte subpopulation of peripheral blood cells, ConA and LPS induced T and B cells proliferation activity tests, Mixed lymphocyte reaction between the donor and the receiptor and the third part, the incidence rate of GVHD and survival analysis were observed in mice after 8Gy TBI with MSCs and haplo-BMT treatment together. These results indicated that MSCs improved stem cells engraftment, promoted lymphcytes and humoral immunity recovery, decreased incidence of GVHD and increased survivals.MSCs increased the IL-10 serum densities, decreased the IL-2, TNF-a serum densities, and MSCs with CM-Dil marked distributed in mice body after 8Gy TBI with haplo-BMT, which proved MSCs repaired injuries organs and prevented multiple organs failure.In a word, MSCs play the immune and hematopoiesis organ radioprotection, improve hematopoietic recovery, promoted lymphcyte and humoral immunity recovery, decreased incidence of GVHD, blocked the MOF occurrence and increased survivals of the ARS mice after haplo-BMT. MSCs and HLA haploid matched hematopoietic stem cells co-transplantation will become an effective method in treating the severe degree ARS in the future.