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

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.

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.

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) > 0.5×109/L, and the average time of 15.0d for platelet count was more than 20×109/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).

Allo-HSCT is safe and effective in patients with SAA and has great clinical perspective.