A recent study on cryo preserved grafts has been undertaken by Dr Pavel Mericka et al who performed a detailed evaluation of the factors around the discard of cryopreserved vascular allografts. The study looked at those manufactured in 2014 and 2015 at the Tissue Bank department of the University Hospital. This tissue bank, operational since 1952, have been cryopreserving specimens since the 1980's using, inter alia, Planer freezers. In the study, all vascular grafts transported to the unit for processing and cryopreservation were included. This amounted to 78 vessels collected from 28 donors. In 2014, 57 vessels were collected, and in 2015, 30.
All the tissue vessels were collected aseptically during multi-organ harvests from deceased donors, aseptically processed in a clean room, cryopreserved in medium containing 10% DMSO and stored in the vapour phase of liquid nitrogen.
The researchers were looking at factors causing discard which included: contra indications of tissue post collection; deviation from the SOPs, problems in processing and storage and microbial contamination and in addition any severe adverse reactions by the graft recipient. The results from the total of 30 grafts not released for clinical use showed that microbial contamination occurred in 22 cases and was the largest cause. In their conclusions the authors point to these results confirming previous experiences - that the most frequent cause of tissue discard was microbial contamination. They do emphasise though the possibility of occurrence of other causes such as contraindication of tissue harvest found at autopsy or unexplained adverse reaction in the recipient of an organ originating from the same donor which should not be neglected.
The Havel Králové Tissue Bank is an institutional member of the European Association of Tissue Banks and annually delivers around 1000 grafts that are used in University and county hospitals as well as in surgeons' private practices.