The use of back-up units to enhance the safety of unrelated donor cord blood transplantation.

The inability to obtain additional stem cells is a disadvantage of unrelated donor cord blood transplantation (CBT). Moreover, in the event of problems with unit shipment, compromised unit quality, thaw mishaps, or graft failure, the time to secure a back-up graft could be unacceptable. Emergent shipment of 1 to 2 back-up units that have been previously typed and reserved could overcome this limitation. However, the advantages of this approach are not established. Therefore, we present our use of back-up units over a 5.5-year period. Six of 121 CBT recipients (5%) required back-up unit infusion. Indications included shipment mishaps (n = 2), poor unit viability (n = 2), significant infusion reaction (n = 1), and graft failure (n = 1). Lack of back-up units would have caused transplantation delay or infusion of inferior-quality units. Five of the 6 patients achieved sustained donor engraftment. We demonstrate that back-up units are emergently required in a significant minority of patients, supporting the incorporation of at least 1 back-up unit in cord blood (CB) selection algorithms to enhance CBT safety.