Abstract 13 Long-Term Stability of Dus Cord Blood Units After >29 Years of Cryopreservation: Follow-Up Data from the José Carreras Cord Blood Bank

INTRODUCTION: The José Carreras Cord Blood Bank (CBB) located in Düsseldorf stores 21215 active cryopreserved cord blood units (CBUs) and has released 1476 CBUs for allogeneic transplantation. The success of transplantations, but also the generation of cells for regenerative medicine for e.g. iPSC reprogramming, significantly depends on the quality of the cryopreserved CBUs after thaw. OBJECTIVES: Therefore, typical parameters like cell count, recovery and viability are analysed from thawed CBUs yearly by a stability monitoring program according to the FACT standards. The longest cryopreservation period in liquid nitrogen tested to date is 338 months (>29 years) for unseparated units and 300 months (25 years) for volume-reduced units that are licensed by the Paul-Ehrlich Institute. METHODS: A retrospective analysis of unseparated CBUs processed from 1993-1997, CBUs processed from 1998-2005 by manual volume-reduction and CBUs processed since 2005 by automated volume-reduction applying the Sepax100 system was performed. In consideration of the distinct processing methods, storage time and existing follow-up data of released transplants, this approach should demonstrate the high CBU quality and proof the long-term engrafting capability of CBUs cryopreserved in liquid nitrogen. RESULTS: According to the CBB stability program means of TNC count (16.32±2.61 x 10(8)), TNC recovery after thaw (106.8±13.91%, above 100% due to earlier applied cell-count method), TNC viability (88.91±5.01%), CD34(+)7AAD(-) viability (90.73±3.69%), CD45(+)7AAD(-) viability (69.09±5.38%) and CFC count (7.10±2.45 x 10(6)) were determined after >29 years of cryopreservation for unseparated CBUs. In volume-reduced CBUs the mean TNC count (9.37±2.14 x 10(8)), TNC recovery (97.78±3.70%), TNC viability (84.22±10.02%), CD34(+)7AAD(-) viability (88.11±5.16%), CD45(+)7AAD(-) viability (73.67±8.31%) and CFC count (1.37±0.59 x 10(6)) were determined after 25 years of cryopreservation. DISCUSSION: In addition, these relevant parameters were retrospectively analyzed for released transplants in correlation to the storage time. The follow-up data of recipients from CBUs demonstrate an earlier engraftment of volume-reduced CBUs as compared to unseparated CBUs in accordance to an increased TNC count over time. With regard to applied processing methods, engraftment time and patient age (children and adults) this retrospective analysis confirms the high quality of old CBUs stored in the liquid phase at -196°C.