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Radiation Sterilization in Tissue Banking

The use of preserved human connective tissue grafts such as bone, cartilage, tendons, skin and amnion has increased tremendously in several disciplines over the last several years. The highest demand is for musculoskeletal allografts which are commonly used for reconstructive surgery in orthopaedics and traumatology. The general purpose of tissue banks is to provide safe and effective allografts for transplantation. The risk of infectious disease transmission with human tissue grafts is a major concern in tissue banking practice. Non-sterilised, fresh or frozen bone allografts collected under aseptic conditions have been associated with transmission of viral infections such as HIV, hepatitis C and B viruses (HCV, HBV) and bacterial infections.

To minimize the hazard of infectious disease transmission, several steps should be undertaken: careful donor screening and selection, proper tissue procurement, processing, preservation, storage and distribution. Even if these procedures are done under aseptic conditions, the possibility of bacterial and viral disease transmission of donor origin cannot be excluded. Therefore, sterilisation of tissue allografts is strongly recommended. Several methods have been applied for sterilisation or decontamination of human tissue grafts including chemicals, heat, UV and ionizing radiation.

Ionizing radiation has been used to sterilize tissue allografts on a large scale. Radiation-sterilisation is a low temperature process, which can be applied when the more commonly used heat sterilisation would cause unacceptable damage to products. The sterilisation efficiency of ionising radiation lies in its good penetrability inside matter (especially gamma rays and X-rays) and its high effectiveness in the inactivation of micro-organisms. It allows for sterilisation of materials in final wrapping.

Controversies exist regarding the optimal dosage required since radiation may also compromise tissue allograft integrity and/or its biological function. Currently several studies initiated by the IAEA are underway to find and validate the optimal dose for several tissues providing graft sterility without compromising tissue allograft integrity/biological function for clinical applications.