Emergency whole-tank transfer of cord blood units after cryogenic failure: A safe rescue strategy

Cryogenic storage of cord blood units (CBUs) is critical to ensure long-term viability and safety. Loss of vacuum in liquid nitrogen (LN₂) tanks is an exceptionally rare but high-risk event that may lead to accelerated LN₂ evaporation and potential warming of stored units.

We describe an emergency rescue transfer following suspected vacuum loss in a BioArchive cryogenic tank at a public cord blood bank. The tank contained 2880 CBUs, including 14 directed units. Progressive LN₂ consumption suggested structural failure, and in situ repair was not feasible. A rapid transfer procedure using a backup BioArchive-compatible tank was performed with the assistance of the manufacturer. The maneuver involved crane-assisted repositioning of the tank under the robotic system and was completed in 40 s. Continuous temperature monitoring confirmed stable vapor-phase conditions throughout the procedure. Six CBUs stored in upper tank positions (worst-case exposure) were evaluated post-thaw. Cell recovery, viability, and clonogenic capacity were preserved and met release criteria for transplantation.

Emergency transfer of CBUs during cryogenic tank malfunction is feasible and can be performed safely without compromising product quality when executed under controlled conditions. This report provides practical guidance for managing rare but critical storage failures in cord blood banking using BioArchive system.