Durable Cord Blood Cell Engraftment in a Patient with Severe Aplastic Anemia after a Matched Sibling Bone Marrow Transplantation and an Unrelated Cord Blood Transplantation.

OBJECTIVE: Severe aplastic anemia (SAA) is a fatal bone marrow failure disease. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) with a matched sibling donor is the first-line treatment for older SAA patients. However, the number of CD34+ cells collected from a matched donor is often lower than expected. To overcome the problem, this study was conducted to combine a matched sibling donor with an unrelated cord blood transplantation for the treatment of a patient with SAA. CASE REPORT: A 45-year-old male patient with SAA was treated with a sibling-matched allo-HSCT. Due to the low amount of donor CD34+ cells, an unrelated umbilical cord blood stem cell transplantation (UCBT) with 9/10 HLA matching was subsequently carried out. Successful hematopoietic reconstitution was achieved by the dual transplantation. Unexpectedly, beginning in the fourth month after transplantation, the sibling donor chimerism was transformed to a stable and complete UCB source. CONCLUSION: This study provides evidence that UCB-derived HSCs have a higher capacity for hematopoietic reconstitution, suggesting that UCB plus an HLA-matched sibling donor is a good alternative for older patients with SAA.