Unrelated Versus Related Donors Cord Blood Transplantation for Children with Non-Malignant Hematologic Diseases.

Allogeneic umbilical cord blood stem cell transplantation (CBT) has been accepted worldwide for curative therapy of many serious hematologic disorders for nearly two decades. To evaluate efficacy and outcomes of unrelated versus related donor CBT in Thai children with non-malignant diseases and to assess feasibility of using cord blood (CB) units cryopreserved in Thai National Cord Blood Bank, we retrospectively reviewed all children undergoing such transplants in our institute from February 2002 to July 2006. There were eligible 11 patients categorized into unrelated group (n=4, 3 male and 1 female) and related donors group (n=7, 6 male and 1 female). Median age and weight were 4 years 9 months (range 1 year 3 months-11 years 9 months), 17.3 kg (range 7.8–55 kg) and 7 years (range 1 year 6 months-14 years 10 months), 19.6 kg (range 13.1–30 kg), respectively. There were 2 cases of β-thalassemia/hemoglobin E, 1 of Wiskott-Aldrich syndrome (WAS), and 1 of severe aplastic anemia (SAA) in unrelated donors group, while every case in related group was diagnosed β-thalassemia/hemoglobin E. 4 unrelated donors consisted of 2 one-HLA-A-allele, 1 one-HLA-B-antigen, and 1 two-HLA-A-B-antigen mismatched cord blood units, while 7 related donors consisted of 5 HLA-identical, 1 two-allele mismatched, and 1 haploidentical siblings. Myeloablative conditioning regimen consisted of busulfan, cyclophosphamide, and anti-thymocyte globulin (ATG) for WAS and thalassemia patients. Fludarabine, ATG, and melphalan were used for the SAA girl because of precedent multiple transfusion received. Cyclosporine was used as graft-vs-host disease (GvHD) prophylaxis in every case. Median numbers of infused mononuclear cells and CD34+ cells of the unrelated donors group were 3.3×10⁷/kg (range 2.4–44) and 2.75×10⁵/kg (range 2.26–25), compared to 1.9×10⁷/kg (range 1.5–3.4), and 1.06×10⁵/kg (range 0.2–5.3) of the related group. Median times to neutrophil and platelet engraftments in each group were 15 and 37 days, compared to 22 and 43 days, respectively. 6 complete donor engraftments were achieved from 3 unrelated CB units and from 3 related sibling donors, however 2 mixed-chimerism status with donor predominance were present from related group. The remaining 1 case of the unrelated group and 2 of the related group did not engrafted, subsequently one case (thalassemia) resumed autologous recovery and unfortunately two cases (thalassemia and SAA) died due to neutropenic septicemia. Acute GvHD occurred in 2 unrelated (skin, gut, liver involvement grade IV (n=1); skin, gut grade II (n=1)) and 1 related (skin involvement grade II) CBT recipients. After immunosuppressive therapy the GvHD lesions were completely resolved in all but one thalassemia boy who suffered from severe fatal grade IV GvHD and eventually died. Median follow-up time for surviving patients was 30 months (range 4–53). Overall and disease-free survival in unrelated donor CBT (n=4) recipients were 50% (n=2) and 50% (n=2), compared to in related donor (n=7) 85.71% (n=6) and 71.43% (n=5), respectively. To date the boy with WAS has been cured by unrelated CBT for more than 4 years. Umbilical cord blood provides a reasonable option for source of hematopoietic stem cells to do transplantation for treatment non-malignant hematologic diseases and the outcome in our study is relatively well and comparable to other studies.