Combined umbilical cord blood and bone marrow transplantation in the treatment of β-thalassemia major

The authors report on three children with β-thalassemia major, class II, III, and III according to the Pesaro classification, with a body weight of 16, 62, and 50 kg, respectively, who received grafts using both umbilical cord blood (UCB) and bone marrow (BM) stem cells from their HLA-matched siblings. The number of UCB nucleated cells collected was 2 x 10⁷/kg, 1.2 x 10⁷/kg, and 2.5 x 10⁷/kg, respectively; and was considered insufficient to secure engraftment. The authors increased the number of hematopoetic progenitors by harvesting BM from the same donors. All 3 patients showed prompt engraftment with neutrophil recovery on days 17, 18, and 17 post- transplant, respectively, and platelet recovery on days 19, 25, and 22 post- transplant, respectively. One patient had remarkably increased HbF of values 31, 19, and 12% at 3, 6, and 12 months post-transplant, respectively, which, were accompanied by an increase in the (G)γ / (A)γ ratio, suggesting UCB- derived hematopoetic reconstitution. All patients are alive and transfusion independent 23, 18, and 16 months post-transplant, respectively. For patients with homozygous β-thalassemia who are at high risk of graft failure, either because of major prior alloimmunization or an insufficient amount of UCB stem cells, combined transplantation with UCB and BM could offer a quick and safe alternative therapy.