Limiting Factors Analysis in Validation of a CryoShipper & a CryoExtra Freezer for Cryo-samples Related to the Abu Dhabi Bone Marrow Transplantation Program

Abstract

<i>Introduction: </i>CryoShipper and CryoFreezer tanks were designed to safely transport and store biological material at cryogenic temperatures. An adverse warming event may occur if the CryoShipper is tilted during transit if temperature and proper levels of liquid nitrogen (LN2) vapors are not maintained. Storing cryogenic hematopoietic stem cell samples for a short or long time requires validating all pieces of equipment employed in a bone marrow transplant program. <i>Objective:</i> To determine the limitations of the <i>MVE CryoShipper CX</i> and the <i>Thermo Fisher</i> <i>CryoExtra™ Cryogenic tank</i> for the Abu Dhabi Bone Marrow Transplantation Program. <i>Methods:</i> The MVE <i>CryoShipper CX</i> was weighted and primed with LN2, and the excess was removed. After stabilizing the temperature, the shipper was tilted onto its side for 24, 72, and 96 hours. The temperature was monitored and recorded at 15 minutes intervals using a <i>Datalogger</i>. After returning to the correct upright position, the dry shipper temperature was also observed for five days after refilling with LN2 to evaluate the secure timing of a shipment. For an LN2 filled <i>CryoExtra</i> tank, dual control of the LN2 level and the temperature was done using manual measurement and automatic display. Later, vials and a bag from three healthy donors’ frozen white blood cell buffy coat samples were kept inside and defrosted daily to measure total mononuclear cell counts CD45+/7AAD cells viability by flow cytometry for five days. <i>Results:</i> The <i>CryoShipper</i> maintained cryogenic temperatures below -150°C for the entire duration of each analysis. A maximum temperature of -182.7°C was reached during the 24-hour tilt experiment from the temperature probe. The <i>CryoExtra 0140</i> freezer temperature was always between -184°C / -194.2°C, and LN2 levels coincided in both measuring methods during the time slot. Stored and defrosted cells keep their % of viability and absolute number over the expected reference range and compare mean+/-standard deviation (SD) between them without assessing the statistical difference with p≥0.05. The defrosted cells’ mean viability of 83.12%, SD±9.04, and a mean of 1,781 cell/µL, SD±1,215. <i>Conclusion: </i>Our modern dry shipper controls much of the vapor within the shipper. The <i>CryoShipper</i> can withstand being tilted during transit for 96 hours without risks of an adverse warming event. The <i>CryoExtra 0140</i> tank its performance was under the established parameters. Both types of cryogenic devices can be used for the safe cryopreservation of cell samples keeping all the security measures and controls as advised.