Storing Tissue Safely

Tissue Services currently provides tissue in 3 formats, freeze dried, frozen and cryopreserved in gas phase nitrogen. All tissue should undergo stock management to ensure the oldest product (with the closest expiry) is used first (this may not necessarily be the most recent delivery). Donated human tissue is a valuable resource and so should be used appropriately and wastage should be minimised, hence stock levels should be kept to a minimum to avoid time expiry. Expired tissue must not be used and must be discarded (customers must not use tissue for non-transplant purposes without prior arrangement as lawful consent may not be in place). Storage temperatures, further information and expiry date is given on pack inserts. The EU Tissue and Cells Directive requires that storage is documented in Standard Operating Procedures, hence these must be in place. Tissue Services recommend, where possible, that blood transfusion laboratories assume responsibility for this task as these types of department are familiar with the need to track products, are equipped with the storage and tracking of human derived material, are familiar with the reporting of adverse events and reactions and they are audited to quality systems e.g. CPA.

Freeze dried tissue e.g. bone

This tissue has undergone a freeze drying process, meaning it does not need special storage temperatures. This means normal ambient or room temperature is all that is required and no monitoring or alarm systems are required. The packaging must be kept dry and must not be exposed to direct sunlight as this can make the packaging brittle and prone to damage. Tissue Services therefore recommends that the tissue is stored in a secure, controlled access, dark, dry place e.g. a drawer or cupboard. The expiry date is indicated on the pack (normally 3 years from donation).

Frozen tissue e.g. bone, tendons, amnion

This tissue must be stored in a dedicated, alarmed freezer/refrigerator. This means a compartment with:

  • Continual temperature recording (e.g. chart recorder or electronic format) which should be checked and authorised against the required temperature limit at least once per week.
  • An audible and visual alarm that indicates when the freezer is out of specification – this alarm must be in a place, or linked to a system, that is manned 24/7.
  • A system in place to respond to alarms 24/7 (either in a 24/7 manned location or linked to an on-call system).

The temperature for storage will depend on the tissue:

  • Bone and tendons need to be stored below -40°C for the full shelf life (3 years from donation). However they can be stored between -20° and -40°C for up to 3 months. When you place your order Tissue Services will ask you for the temperature of the freezer you are intending to use, to ensure the correct labelling and expiry date is printed on the product prior to supply. Once thawed, tissues can be placed in a +4°C refrigerator for up to 24 hours. Do not re-freeze.
  • Amnion must be stored below -40°C as the high concentration glycerol it is stored in liquefies above this temperature. Once thawed, they can be placed in a +4°C refrigerator for up to 24 hours. Do not re-freeze.

Cryopreserved tissue e.g. skin, heart valves

This tissue is stored in vapour phase nitrogen at below -135°C at Tissue Services and is usually supplied in dry ice (-79°C). It should not be returned to nitrogen storage (if you need to do this, please seek advice from Tissue Services). This product can be stored in a dedicated alarmed freezer running at -80°C (please see requirements above in frozen tissue section) until the expiry date (permitted 6 months storage). Once thawed, it can be placed in a +4°C refrigerator for up to 24 hours. Do not re-freeze.

National Order Line:
0845 607 6820

National Fax Line:
0845 607 6819

Tissue Services

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