Abstract 7: Influence of Long-term Storage of Cryopreserved Automated Volume-Reduced Cord Blood Units Until 20 Years: Analysis From Barcelona Cord Blood Bank, Spain.

Abstract Introduction Barcelona Cord Blood Bank (BCBB) program started for CB units (CBU) donations in 1991. In 2002, Automated Volume-Reduced method was introduced applying the closed System (Sepax®, Cytiva). In order to ensure the quality of cryopreserved units after long-term storage, CBB programs evaluate cell recovery, progenitor cells functionality such as viability and Colony forming unit (CFU), and myeloid recovery after cord blood transplant (CBT). Objectives This retrospective study investigated quality parameters of CBUs stored for 1-20 years processed by automated volume-reduced and cryopreserved and stored in Bioarchive® system, (Thermogenesis) showing the effect of cryopreservation on variables measured both pre- and post-thaw. Additionally, we analyzed engraftment after CBT transplantation according to CBU time storage. Methods CBUs used for transplantation between2002 to 2022 were included in the study. To evaluate the influence of long-term storage of cryopreserved CBUs, Kruskal-Wallis correlation test between quality variables was performed. We studied correlation between pre-cryopreservation and post-thaw values (recovery) of TNC and CD34+ counts, CD45+ and CD34+ viability, CFU and CFU-FM counts. Additionally, myeloid engraftment was evaluated categorizing whole population in 3 groups according CBU storage duration: short-term (≤ 2 years), medium-term ( 2 and ≤ 5 years) and long-term ( 5 years). Results A total of 1577 CBUs with a median of 3.9 (range 1.3-20 years) of cryopreservation storage were evaluated. The median of TNC and CD34+ recovery, CD45+ and CD34+ recovery, CFU and CFU-GM recovery were 81.7%, 79.9%, 54.4%, 73.3%, 58.2% and 26.5%, respectively. Analysis demonstrated a non-significance decreased in CD34+ counts recovery, infused CD34 + 7AAD-viability and CFU-GM counts (P = 0.12, P = 0.28 and P = 0.96, Figure 1), respectively. Neutrophil engraftment at 42 days after CBT was found significantly faster for short-term stored CBUs (98%; CI95%, 96-99%, P = 0.015, Figure 1). No significance difference was found in platelet engraftment at 60 days between CBUs storage time groups (P = 0.5). Discussion Most quality parameters results evaluating CBUs demonstrated no significance decrease up to 20 years of cryopreservation meaning likely successful clinical transplantation of CBUs following long-term storage. Long-term cryopreserved CBUs continue to fulfil release FACT-Netcord requirements.