Long-Term Stability of Cord Blood Units After 29 Years of Cryopreservation: Follow-Up Data From the Jose Carreras Cord Blood Bank

The Jose Carreras Cord Blood Bank (CBB) located in Dusseldorf as of today stores 21 215 active cryopreserved cord blood units (CBUs) applicable as a source for hematopoietic stem cell (HSC) transplantation. Since the success of transplantation outcomes is mainly dependent on the cord blood quality, typical parameters are evaluated by a Stability Monitoring Program specified by the FACT Standards. The longest expiration time determined to date is 29 years for unseparated units, 25 years for manual and 18 years for automated volume-reduced units licensed by the Paul-Ehrlich Institute. According to the CBB stability program TNC count, TNC recovery, TNC viability, CD34+7AAD- viability, CD45+7AAD- viability and CFC count were determined for all 3 processing methods applied over time. As a measure of stability, unseparated units (processed 1993-1998) revealed a mean TNC viability of 88.91 +/- 5.01% after 29 years of cryopreservation versus manual volume-reduced CBUs (processed 1998-2005) with a mean of 84.22 +/- 10.02% after 25 years of cryopreservation versus automated volume-reduced CBUs (processed since 2005) with a mean of 88.64.91 +/- 3.91% after 18 years of cryopreservation. In addition, these relevant parameters were retrospectively analyzed for released transplants in correlation to the storage time. Moreover, the follow-up data of recipients from CBUs cryopreserved directly (unseparated) versus CBUs cryopreserved after manual versus automated volume-reduction are presented here demonstrating an earlier engraftment in both volume-reduced groups as compared to unseparated CBUs. By this retrospective analysis, key questions are discussed regarding cord blood parameters in relation to processing methods, engraftment, and patient age (children and adults). Graphical Abstract