Validation of cold chain shipping environment for transport of allografts as part of a human tissue bank returns policy

Human tissue is shipped to surgeons in the UK in either a freeze-dried or frozen state. To ensure quality and safety of the tissue, frozen tissue must be shipped in insulated containers such that tissue is maintained at an appropriate temperature. UK Blood Transfusion Service regulations state “Transportation systems must be validated to show maintenance of the required storage temperature” and also state that frozen, non-cryopreserved tissue “must be transported… at −20 °C or lower” (Guidelines for the Blood Transfusion Services in the United Kingdom, 8th Edn. 2013). To maintain an expiry date for frozen tissue longer than 6 months, the tissue must be maintained at a temperature of −40 °C or below. The objective of this study was to evaluate and validate the capability of a commercially available insulated polystyrene carton (XPL10), packed with dry ice, to maintain tissue temperature below −40 °C. Tissue temperature of a single frozen femoral head or a single frozen Achilles tendon, was recorded over a 4-day period at 37 °C, inside a XPL10 carton with dry ice as refrigerant. The data demonstrate that at 37 °C, the XPL10 carton with 9.5 kg of dry ice maintained femoral head and tendon tissue temperature below −55 °C for at least 48 h; tissue temperature did not rise above −40 °C until at least 70 h. Data also indicated that at a storage temperature lower than 37 °C, tissue temperature was maintained for longer periods.