Aldehyde dehydrogenase activity in cryopreserved cord blood cells for quality assessment prior to transplantation.

In umbilical cord blood transplantation (UCBT), the number of cluster of differentiation (CD)34+ cells and colony‑forming units (CFUs) in the cord blood (CB) graft positively correlate with patient survival. Therefore, these parameters are currently used for quality assessment of the cryopreserved CB cells in the attached segment that is considered representative of the CB in the main bag prior to UCBT. Since aldehyde dehydrogenase (ALDH) activity is high in hematopoietic stem cells, the number of ALDH‑bright (ALDHbr) cells was examined in comparison with the number of CD34+ cells and CFUs for the quality assessment of CB units. In the cryopreserved main bag, the number of ALDHbr cells in the CB unit exhibited positive correlation with the number of CD34+ cells, and with CFU‑granulocytes/macrophages and total CFU counts. Furthermore, the concentration of ALDHbr cells in the cryopreserved attached segment was not significantly different compared to that of the main bag, suggesting that the attached segment is representative of the main bag. In conclusion, the present study suggested that ALDHbr cell counts in the cryopreserved attached segments may serve as a quality assessment indicator for CB units prior to UCBT.