A Clinical Analysis Of Non-myeloablative Allogeneic Bone Marrow Combined With Peripheral Blood Hematopoietic Stem Cell Transplantation For Severe Aplastic Anemia

Aplastic anemia is a disorder of bone marrow failure cuased by many factors,which is characterized by pancytopenia and the low proliferation.of bone marrow.The diagnosis of SAA need meet the following standard: The proliferation degree of bone marrow <25% of normal or <50% with normal hematopoietic cells <30%,and 2 or 3 of the following peripheral blood cell parameters:①neutrophil counts <0.5×10^9/L;②absolute reticulocytes counts <40×10^9/L or transfusion dependence;③platelet counts <20×10^9/L.Neutrophils counts <0.2×10^9/L is very severe aplastic anemia.Recent experimental results show that T cell-mediated immune attack hematopoietic stem cells (HSC) is the pathological basis of AA,the effec of immunosuppressive therapy (immunosupressive therapy, IST) precisely support this theory.SAA has poor clinical prognosis and high mortality with the natural course of 6 months or so.Allogeneic bone marrow transplantation and immunosuppressive therapy are Currently available treatments of SAA. As we know immunosuppressive therapy has high recurrence rate,bone marrow transplantation can cure SAA.However,the major hurdles that needs to be overcome in the allo-genetic transplantation setting are graft rejection,chronic graft-versus-host disease (a / cGVHD),conditioning regimen-related complications and higher mortality rates of bone marrow suppression.With conditioning regimen having been improved,such as irradiation T cyclophosphamide(CTX) and anti-lymphocyte globulin(ALG),the engraftment increased in ten years recently.But the incidence of transplant-related complications increased also, resulting in little change in the overall outcome.This study used lower dose nonmyeloablative conditioning methods,,allogeneic bone marrow Combined with peripheral blood mobilized by G-CSF stem cell transplantation to treat 17 patients with SAA, and aims to observe the short and long term efficacy of this method.Methods: The conditioning regimen: 14 patients were treated with cyclophosphamide (CTX) 60mg / (kg.d)×2d and anti-lymphocyte globulin (ALG) 40mg / (kg ? d) or anti-thymocyte ball protein (ATG) 6.25mg / (kg ? d)×4d intravenous drip. The other 3 patients with a history of hepatitis B treated with fludarabine (Flu) 35mg / (m2. d)×6d, CTX 60mg / (kg.d)×2d and ATG 2.5mg / (kg ? d)×3d intravenous drip.Short methotrexate (+1 d 15mg / m2, +3, +6, +11 d 10mg / m2) combined with cyclosporin A (CSA) was administeced as GVHD prophylaxis.Oral prednisone was used to prevent serum sickness.G-CSF (5ug / (kg.d)×5d was used to mobilize peripheral blood stem cell. Donor injected with G-CSF 5ug / (kg. D) for 5days.We used a blood cell separator to collect G-CSF-mobilized peripheral blood stem cell and collected the iliac bone marrow in the sterile operating room. The numbers of MNC, CD34 cells in the collection peripheral blood stem cells were 4.88 (5.66-8.06)×10^9/kg,2.99 (0.92-9.06)×10^9//kg respectively. In the bone marrow were 1.13 (0.54-1.86)×10^9//kg,2.06 (0.35-5.65)×10^9//kg.The total infused numbers of MNC, CD34 cells was 6.18 (3.38-10.55) * 10 ^ 6/kg, 3.36 (1.26-14.20) * 10 ^ 8/kgrespectively.Microsatellite loci DNA fingerprinting,sex chromosomes and ABO blood group were used for testing situations for those implants. Results: 16 patients got hematopoietic reconstitution in a short time.Time to neutrophil engraftment was 14.5(2-32) d.The median time to platelet engraftment was 32.5 (5-109) d.5 patients got peripheral blood stem cells infusion again because of Pancytopenia or thrombocytopenia after transplantation.The detail complications of this group patients are the following:acute GVHD (II degree),chronic GVHD (extensive type) both 1 case ,empyema 2 cases, sepsis 4 cases, cytomegalovirus viremia10 cases, fungal infection 7 cases.One patient with HbeAb(+)HBcAb(+)HBsAb(+) before transplantation converted into HbeAg(+) HBcAb(+) HBsAg(+ ) after fifteen days'transplantation. Till marth 2011,with a median follow-up of 28 months ,13(76.5%)patients were survival. of The expected 5-year survival rate is about 82%.by Kaplan-Meier survival analysis.Two male patients had birth normal child after transplantation. All female patients still keep normal menstrual cycle after transplantation.Conclusion: 1.The method of nonmyeloablative preconditioning has low toxicity.The patients can tolerant better and will have high quality of life after transplantation with this method. 2. The method of nonmyeloablative preconditioning can form a stable chimerism that can reduce the incidence of GVHD and gaft rejection after transplantation. 3.DSI can help donor cells to implant into patients'bone marrow fastly and induce MC into CC.4. The G-CSF-mobilized PBSC has abundant CD34+ cells that can speed hematopoietic recovery and can reduce bleeding and early mortality; Bone marrow stromal cells can help the body to recover hematopoietic microenvironment and reduce the incidence of GVHD. Transplantation with both can improve effect.5.The transplantation-related infection remains high, which may relate with immunization treatment or infection before transplantation.