Criteria for storage of cord blood units at Japan's largest cord blood bank

Abstract

AbstractBackground and ObjectivesIn Japan, cord blood transplantations exceed those done with adult‐sourced unrelated stem cells. This study analyses cord blood (CB) storage criteria to maintain high‐quality CB units.Materials and MethodsThe Kanto‐Koshinetsu Cord Blood Bank received 29,795 units from 2014 to 2021, mostly >60 mL, and 5486 (18.4%) were stored as transplantable units. We investigated the mother's gestational period, CB volume, total nucleated cells (TNCs), CD34+ cells, total colony‐forming units (CFUs), time from collection to reception and cryopreservation, cell viability, and the reasons for not storing a unit.ResultsThe average time from collection to reception of 29,795 units was 18.0 h. The most common reason for not storing a CB unit was low cell numbers (pre‐processing TNC count <1.2 billion), accounting for 67.9% of the units received. There was no correlation between the CB volume and the CD34+ cell count. The shorter the gestational period, the lower the TNC count, but the higher the CD34+ cell count. There was no correlation between the time from collection to cryopreservation, within a 36‐h time limit, and the CD34+ cell recovery rate.ConclusionWe could accept units with a TNC count <1.2 billion and a CB volume <60 mL from a gestational period of 38 weeks or less if we did a pre‐processing CD34+ cell count. This would secure more units rich in CD34+ cells.