Feasibility of Unfrozen Sub-zero Storage of Mammalian Tissues with Insect Anti-Fr

DESCRIPTION (provided by applicant): The long term goal is the development of better, longer hypothermic storage conditions for liver transplants than currently possible in clinical practice using novel insect antifreeze proteins. Hypothermic injury result s in vascular dysfunction during liver storage, therefore vascular tissue models will be employed in this Phase I SBIR proposal. Blood vessel rings, derived from rabbit jugular veins and carotid arteries, will be employed because they will permit dissectio n of hypothermic storage effects upon the morphology and functional viability of vessels and because these studies can be performed with the small quantities of insect-derived antifreeze proteins that can be produced with our current manufacturing methods. Scale up of antifreeze protein production to achieve the quantities required for livers is not possible within the economic limitations of a Phase I SBIR proposal. The use of hypothermia as the principal means to suppress metared with controls without ant ifreeze proteins in order to increase the duration of hypothermic storage. The test temperature, -10xC, was selected on the basis of the greater non-colligative freezing point depression produced by the insect antifreeze peptides that provide almost an ord er of magnitude greater activity compared with other previously described antifreeze proteins derived from other sources. The insect-derived antifreeze proteins will inhibit ice nucleation at -10xC permitting mammalian tissue storage at much lower levels o f endogenous metabolic activity. These storage conditions should lead to longer hypothermic storage periods for tissues and organs. In this Phase I SBIR proposal insect-derived antifreeze protein formulations, selected from research studies on thermal hyst eresis by our consultant, Professor John Duman, and controls will be compared employing rabbit venous and arterial tissue models and a panel of assays for evaluation of the histopathology and physioloan livers in a subsequent Phase II SBIR proposal. PUBLIC H HEALTH RELEVANCE: Livers destined for transplantation are currently stored using static cold storage in a chemically defined solution at 4xC for periods of up to 6 hours. However, the application of static cold storage has proven to be insufficient to fu lfill the organ demand for patients with irreversible liver failure, because marginal livers can not be preserved optimally, for long enough, by static cold storage to permit organ evaluation to occur. These limitations should be overcome by use of a lower , sub-zero hypothermic temperature (-10xC) to further reduce metabolism in combination with insect-derived antifreeze proteins to inhibit ice nucleation resulting in increased availability of organs for transplant.