[Allogeneic stem cell transplantation for 8 patients with malignant infantile osteopetrosis in China].

OBJECTIVE: Osteopetrosis is a rare genetic disorder and the malignant infantile osteopetrosis (MIOP) is the worst subtype of this disease. Seventy percent of patients die in six years of life without proper treatment. Hematopoietic stem cell transplantation (HSCT) offers the only chance of cure for MIOP.

METHOD: Retrospective analysis was performed on 8 patients with MIOP who underwent HSCT in Beijing Children's Hospital during the period from 2006 to 2011.

RESULT: Eight cases (4 male and 4 female, mean age at HSCT 13.5 months) were diagnosed as malignant infantile osteopetrosis. Conditioning regimen included fludarabine, busulfan and cyclophosphamide. All patients received cyclosporin for prophylaxis of graft vs. host disease (GvHD). A UMD recipient underwent CD34(+) cell selection. ATG/ALG, mycophenolate mofetil (MMF) and methotrexate (MTX) used for recipients with unrelated cord donor (2) and recipients with haplo-identical donors (5). Average time for neutrophil engraftment was 15.7 day (9 - 36), platelet engraftment was 43.3 day (10 - 68). The patients were followed up from 47 days to 5 years, 1 patient died of post-transplant complications. Seven cases presented better in clinical manifestation. Acute GvHD I°-II° was observed in 6 patients, III°-IV° in 2 patients. It was controlled by anti-GvHD therapy.

CONCLUSION: Non-allogenic stem cell transplantation treatment of infantile MIOP showed high survival rate and restoration of hematopoiesis in haploid transplant patients, therefore, non-allogenic HSCT may be an option to treat MIOP in children.