Terminal sterilization of tendon allografts to the same levels called for in medical devices is currently all but non-existent. Terminal sterilization using ethylene oxide gas leaves toxic residues and negatively impacts the probability of positive outcomes following ACL surgeries. Gamma irradiation is used to sterilize grafts but at the irradiation levels sufficient to achieve sterilization the tendon is rendered unusable because separation of collagen bundles and denatured proteins result in significant weakening of the graft. An ideal method for sterilization of tendon allograft material would be one that is terminal, non-toxic, retains the essential properties of the allograft, and is validated to achieve sterility assurance level of 10-6 (the same level required for medical devices). Our preliminary experiments indicate that sterilization by our supercritical CO2 process represents a viable solution to answer the pressing need to terminally sterilize tendon allograft material. We request support to develop a validated terminal sterilization process for tendon allografts utilizing supercritical CO2. The specific aims of this proposal are (1) To develop a procedure for terminal sterilization of tendon tissues with supercritical carbon dioxide; (2) To analyze post-sterilization tendon tissue samples for potential biomechanical alterations and compare them with untreated. The long-term objective of this project is to develop a commercially viable terminal sterilization method that would be compatible with human soft tissues and would eventually add a terminal sterilization component to current tissue bank practices. Phase II studies will consist of comprehensive testing to verify inactivation of viral and fungal contaminates in tendon as well as tests using animal models to evaluate histological and biomechanical changes in supercritical CO2 sterilized implanted allograft tendons through the phases of graft necrosis, revascularization, fibroblast invasion and collagen synthesis. Furthermore this technology may be expanded for use in other tissues where donor cell viability is not a concern. [unreadable] [unreadable] [unreadable]