Clinical applications of haploidentical hematopoietic stem cell transplantation in severe aplastic anemia

OBJECTIVE: The purpose of this study was to investigate the efficacy and safety of haploidentical allogeneic hemopoietic stem cell transplantation (allo-HSCT) in severe aplastic anemia (SAA) and prophylaxis of complications involved. PATIENTS AND METHODS: 8 patients with clinically diagnosed SAA (5 cases of SAA-I and 3 cases of SAA-II) were recruited, with the parents as the donors of hemopoietic stem cells. The conditioning regimen before HSCT included cyclophosphamide, fludarabine, pig anti-human lymphocyte immune globulin (p-ALG) and/or total body irradiation (TBI). The recipients received short-term methotrexate (MTX), mycophenolate mofetil (MMF), and cyclosporin A (CsA) for graft versus host disease (GVHD) prophylaxis. Subsequent to successful allo-HSCT, the hematopoietic reconstitution was observed, coupled with periodical surveillance of the chimerism rate, the occurrence, and severity of postoperative complications as infection, GVHD, veno-occlusive disease (VOD), hemorrhagic cystitis (HC), cytomegalovirus (CMV) as well as the long-term survival rate, etc. RESULTS: We found that hematopoietic reconstruction was achieved in all of the 8 patients with the average time of 14.8d for absolute neutrophil count (ANC) > 0.5x10(9)/L, and the average time of 15.0d for platelet count was more than 20x109/L. Follow-up for 1 month later revealed that DNA chimeric rate of donor cells was 95%-100%. The complications were aGVHD in 7 cases including 5 cases of grade I-II (62.5%), 1 case of grade III (12.5%) and 1 case of grade IV (12.5%), as well as chronic graft versus host disease (cGVHD) in 2 patients, including 1 case (12.5%) localized in the oral cavity and 1 case (12.5%) with extensive type cGVHD in the whole body skin. No VOD or HC was observed, and no transplantation-related death occurred at median following-up of 8.5 months (2 to 18 months). CONCLUSIONS: Allo-HSCT is safe and effective in patients with SAA and has great clinical perspective.