Guidelines on processing and clinical use of skin allografts

Processing methods used for banking of skin for subsequent therapeutic use depend on whether the skin is to retain viability or not. For viable skin grafts, sterilisation techniques cannot be applied, however antibiotics and antimycotics may be used to disinfect the tissue with respect to bacteria and fungi. Nevertheless, strict standards are applied to avoid disease transmission from donor to recipient involving donor medical history, donor testing for viral diseases, aseptic retrieval and processing, and control of storage temperature. Cryopreservation is the preferred method for long term storage of viable skin grafts. If viability is not required, then additional long term preservation methods may be used including deep-freezing, freeze-drying or high concentration solute preservation. All three methods work by reducing water activity. In addition it is possible to apply certain sterilisation techiques that have been shown not to damage the tissue. It is important that sterilisation methods are validated in accordance with precise definitions of sterilisation, and for the initial levels of “bioburden” expected to be present immediately prior to application of the sterilisation method. The application of improved and refined methodologies in accordance with defined standards has ensured improved graft performance while reducing risk to the recipient.