Post-Release Breakage Rate of Cryopreserved Cord Blood Products (CB) Shipped to 135 Transplant Centers from a Single Cord Blood Bank.
Authors: Law Ping , Wang Brian , Gindy Laura , McCarter Matt , Hernandez Jerry , Bolanos Rafael , Hwee Susanna , Chen Joshua , Chen Albert , Lew Matt , Chow Tiffany , Petz Lawrence , Chow Robert 
Published: April 2020

CB are becoming a common source of hematopoietic stem cells for transplantation. CB are collected, cryopreserved, and then transported to transplant centers (TC) in dry shippers. Recently, McKenna et al, reported that the breakage rate of CB received at a single TC was approximately 3.5% or 24 out of 679 CB (Transfusion48:1138; 2008). The CB were procured from various banks where units were processed using different procedures and stored in different freezing bags. In this report, we took instead the single cord blood bank approach and calculated the CB breakage rate from a single bank (StemCyte) with all units processed using an identical procedure (plasma depletion without RBC reduction) and cryopreserved in one type of container (Cryocyte-250). Between Nov 2001 and July 2008, we received feedback from TC on 597 CB shipped (using dry shippers and standardized procedures) to 135 TC – 54 US (425 units) and 81 non-US (172 units). Median volume in each cryopreserved bag was 75 ml (range: 51–100) containing 1.62 × 109 median total nucleated cell (TNC) (0.42 – 4.77 × 109) and stored in vapor phase of liquid nitrogen (LN) freezers for a median of 33 months (2 to 87). The CB were inspected to be free of defects prior to shipment. A total of 5 CB were reported to be “broken” (breakage rate of 0.8%) by the receiving TC, which is significantly lower than the published value of 3.5% (p=0.0013, test of proportions). For 4 units, initial inspection after receipt by TC revealed no issues, and breakage was discovered during thawing or infusion (small cracks or leaks) and all were infused. No infection or other serious adverse events related to the breakage were reported by the TC. For the 5th CB, breakage occurred at the point of heat-seal between the segment and the Cryocyte bag and the unit was not infused. The TC reported dropping of this CB when the dry shipper lid was opened, which likely caused the break. Characteristics of the CB with breakages are shown in Table 1 and appeared to be similar for all shipped units. Investigation of the CB at the originating bank included a detailed review of processing records and shipping histories, and no abnormalities were noted. The CB with breakages were collected from different hospitals at different times, processed by different technologists, and stored in the vapor phase of different LN freezers. The Cryocyte bags were from different lots and no other breakages were reported from other CB processed and cryopreserved at the same time using the same lots of reagents and bags. It is not known whether the significantly higher breakage rate reported in the literature may be the result of variables such as using different freezing bags, processing procedures, lack of pre-release inspection, or liquid phase LN storage. In conclusion, our results from a single bank showed that CB breakage rate (post release) was low and the broken products have no discernibly different characteristics from other shipped units; therefore, the breakages appeared to be isolated and random post-release events.

Table 1: Characteristics of CB with post-release breakage

TNC × 10−9 Median (Range) Volume per bag Storage time (months) All CB 1.62 (0.42 – 4.89) 75 (51 – 100) 33 (2 – 87) CB#1 (Crack) 2.35 57 17 CB#2 (Leak) 1.34 75 35 CB#3 (Leak) 0.59 75 25 CB#4 (Crack) 1.11 75 26 CB#5 (Seal) 1.32 53.5 33