A Method for Reduction of Bioburden in Bone Allografts

DESCRIPTION (provided by applicant): A new method of bone tissue terminal sterilization using supercritical CO2 is proposed for accomplishing industrially acceptable levels of bacterial inactivation. Preliminary experiments reveal that unlike gamma-irradiation, supercritical CO2 does not reduce the mechanical strength of bone. Recent events related to unsafe tissue supplies highlight the need for a technology that can terminally sterilize tissue while maintaining the essential properties of the tissue. The tissue banking industry has invested in costly clean room technologies, complicated and unvalidated non-terminal disinfection techniques to respond to impending FDA regulation. Our preliminary evidence suggests that sterilization using our proprietary method is a viable solution to this ongoing dilemma. The specific aims of this proposal are: 1. To develop a procedure for terminal sterilization of bone tissues with supercritical carbon dioxide. 2. To analyze post-sterilization bone tissue samples for potential material alterations and compare them with untreated and gamma irradiated samples. Introduction of CO2 sterilization to the tissue bank industry can be accomplished quickly once a satisfactory set of tests with bioindicators is accomplished. There is still no FDA sterilization regulation in the tissue bank industry today. Current gamma sterilization has about a 3 log reduction of the B. pumilus bio-indicator from a 106bioburden. Higher doses of gamma can severely weaken bone to an unusable condition. Current work at NovaSterilis has accomplished sterilization of spiked bone tissue by demonstrating total inactivation of the bioindicators: B. subtilis and stearothermophilus endospores. The long-term objective of this project is to develop a commercially viable sterilization method that would be compatible with human bone tissues processed for transplantation where cell viability is not a concern and would eventually replace gamma radiation sterilization. The new CO2 based sterilization technology produces no environmentally hazardous byproducts, and should be readily transferred to the biomedical industry. The commercial sterilization reactor would use carbon dioxide in a closed-system (similar to many CO2 -based extraction systems) where used CO2 would be purified and reused again (complete recycling system).