Study On Prophylaxis Of GVHD Afte Nonmyeloablative Bone Marrow Transplantation In H-2 Haploidentical Murine Model

Nonmyeloablative allogeneic hematopoietic stem cell transplantation (NST) is brought forward recent years. It is a modified transplant technology, which induced stable hematopoietic mixed chimerism and tolerance through immunosuppressive and nonmyeloablative regimen. HLA haploidentical transplantation has a high incidence and severity of GVHD (graft-versus-host disease). In order to reduce the incidence and severity of GVHD, study on HLA haploidentical NST is a important task for us.Our experiment used a P-*F1 transplant model, donors were C57BL/6J mice, recipients were C57BL/6JxBALB/C hybridized mice. Nonmyeloablative regimen consists of fludarabine, arabinoside cytosin, cyclophosphamide and 2Gy total body irradiation. The experimental mice were divided into five groups: Group 1 was only given nonmyeloablative conditioning, which was not infused donor stern cell; Group 2 mice was transplanted, which was not given prophylaxis of GVHD, Group 3,4,5 were given CSA(Cyclosporin A) + MTX (Methenyltetrahydrofolate), CSA+MMF (Mycophenolate Mofetil), CSA+MTX+MMF for prophylaxis of GVHD respectively.The results showed that Group 1 regained its hematopoietic recovery on day 14 post transplant. FCM(flow cytometry) assay indicated donor-derived cell could be inspected on day 4 post transplant, the proportion of chimerism increased gradually, reached a high peak (88.0%) and kept more than 60% stably on 45 days in the groups with prophylaxis of GVHD. 75% mice without prophylaxis of GVHD showed the typical signs of aGVHD, the clinical GVHD score was 4.0. The morbidity and mortality of GVHD and clinical GVHD score for mice were 40%, 62.5% and 2.6 (CSA+MTX), 33.3%, 60% and 2.4 (CSA+MMF), and 26.7%, 50% and 2.3 (CSA+MTX+MMF ), respectively. Compared to the group without prophylaxis of GVHD, there wasobviously statistical different (p<0.05).According to the pathologic evidence , Group 2 had II-IV GVHD and Group 3,4,5 had I-IIGVHD.In conclusion, our preparative regimen was nonmyeloablative and well-toleranced, which could obtain the survival grafts stably. The mice had typical signs of GVHD without prophylaxis of GVHD. MMF +CSA+MTX was the best combination in prevention GVHD. H-2 haploidentical murine GVHD model with NST was successfully established.