Storage conditions and expiration periods must be supported by validation. Historical data, experience and documented literature are acceptable as evidence of validation. Any new processing or significant changes to existing processing are subject to pre-authorisation by the HTA.
Tissue must be subjected to one of the following treatments, as soon as possible and within 24 hours of retrieval:
In the case of tissue taken from heart-beating donors in the operating theatre at the time of organ retrieval, this period may be extended to 48 hours.
Tissue with terminal antimicrobial processing must be subjected to one of the treatments detailed in the above section within 24 hours of retrieval with a maximum of 72 hours following death. A summary of the guidance regarding temperature/time relationships contained in these guidelines is given in Tables 21.1 and 21.2.
Table 21.1 Temperature/time relationships for banked tissues from living donors
Retrieved tissue |
Must be placed at an ambient temperature of 0–10°C within 4 hours of retrieval. |
Bacteriostasis |
Freezing tissue to at least –20°C within 24 hours of retrieval can be used as a bacteriostatic treatment. |
Long-term storage |
Bone from living donors may be stored at –20°C or lower for up to 6 months or at –40°C or lower for up to 5 years. Temporary storage of frozen living donor bone between –20°C and –40°C is limited to 6 months in total. Grafts stored at this temperature must then be transferred to –40°C or colder to give an expiry of up to a maximum of 5 years from donation. |
Transportation and local storage |
Must be transported and stored locally prior to clinical use, at –20°C or lower in order to have the designated expiry (specified above). |
Table 21. 2 Temperature/time relationships for banked tissues from deceased donors
Retrieval | For eyes, retrieval must be completed within 24 hours after death and the body should preferably be refrigerated For all other tissues, if the body has not been refrigerated, procurement of tissues must be completed within 12 hours after death. If the body has been refrigerated within 6 hours of death procurement should preferably start within 24 hours and must be completed within 48 hours of death. |
Retrieved tissue |
Must be placed at an ambient temperature of 0–10°C within 4 hours of retrieval. |
Bacteriostasis |
Freezing tissue to at least –20°C within 24 hours of retrieval (or up to a maximum of 72 hours of death) can be used as a bacteriostatic treatment. |
Long-term storage |
Frozen* non-viable tissue may be stored: |
Transportation and local storage |
Frozen* tissues must be transported and stored locally prior to clinical use, at –20°C or lower in order to have the designated expiry (specified above). |
For the purposes of this guidance, the following definitions apply: * Frozen tissue – tissue frozen and stored under conditions unlikely to be compatible with preservation of cells. ** Cryopreserved tissue – tissue treated with a cryoprotectant and/or cooled at a controlled rate in order to preserve cells. |
It is the responsibility of the designated medical officer or designated microbiologist to develop written policies regarding the selection and conduct of tests for bacterial and fungal contamination and the acceptance criteria for specific tissues.
Where tissues are shown to carry viable bacteria or fungi they may be suitable for clinical use (e.g. skin grafts) depending on microbial types and densities of growth on culture. For other tissues the material may be approved for use provided that a validated antimicrobial processing technique is used.