Transplantation of highly purified CD34+ progenitor cells from alternative donors in children with refractory severe aplastic anaemia

Without transplantation from a human leucocyte antigen-identical family donor, refractory severe aplastic anaemia (SAA) has an unfavourable prognosis. Conventional transplantation from a matched unrelated donor carries a high rate of mortality. We transplanted large numbers of highly purified CD34 + cells from matched unrelated (n = 4), mismatched unrelated (n = 4) and mismatched related (n = 1) donors into nine children with refractory SAA. The grafts consisted of granulocyte colony-stimulating factor-mobilized peripheral positively selected CD34 + cells. A median of 15.1 x 10 6 /kg CD34 + stem cells and 11 x 10 3 /kg CD3 + T-lymphocytes were infused. No additional pharmacological graft versus host disease (GVHD) prophylaxis was given. At a median follow-up of 47 (range 37-72) months, eight patients (89%) were in complete remission with >90% donor chimaerism and no evidence of GVHD. One patient died on day +238 as a consequence of GVHD. The use of highly purified mobilized CD34 + stem cells warrants further clinical exploration in children with refractory SAA.