*Purpose: The current status of organ transplantation demands consideration of extended criteria (ECD) brain dead donors (DBD) as well as donation after circulatory death (DCD) organs for clinical use. Development of methods for improving preservation and viability of organs is critical for effective utilization of such donor organs. Studies show that even during hypothermic preservation, there is metabolic activity which results in depletion of adenosine triphosphate (ATP) stores, leading to apoptosis and tissue necrosis. Additional oxygen may support the mitochondrial synthesis of ATP and delay the injury process. Perfluorocarbons (PFC) are non-polar fluorine saturated polycarbons capable of dissolving and carrying significantly greater concentration of oxygen than whole blood. They adequately oxygenate tissue in the absence of red blood cells. Our hypothesis was that storage of deceased donor organs by adding oxygenated PFC, will improve tissue viability, prolong preservation time, decrease cellular injury and potentially increase utilization of organs. Aim- To determine if oxygenated pure PFC or adding oxygenated PFC to the standard University of Wisconsin (UW) solution during cold storage can support better organ preservation.

*Methods: Porcine kidneys were subjected to a 60 min warm ischemic injury to mimic a DCD organ scenario. The organs were flushed and stored at 4° C in pure PFC or a 5% PFC+UW emulsion with intermittent flushing via the cannulated renal artery for 40 hrs. Tissue oxygen tension and decay curves are captured with continuous real time computer monitoring using Licox oxygen and temperature probes (Integra®LICOX). Tissue samples were collected after flush (baseline), 24hr and 40hr time points and stored at -80° C. Renal tubular injury was assessed using paraffin sections stained with hematoxylin & eosin (H&E) and graded as mild, moderate or severe. Immunohistochemistry using TUNEL assay was used to evaluate apoptosis. All tissue slides were reviewed and reported by an expert histopathologist.

*Results: 10 male Yorkshire pigs were used as per approved Institutional Animal Care and Use Committee (IACUC) protocols. The organs were stored in either a static pure PFC (n=5) or a 5% PFC+ UW emulsion (n=5). 50% oxygen was continuously bubbled into the preservation solution. The kidney tissue oxygen concentration (PtO2) stabilized and reached a baseline 0.0 mmHg within 15 min after placement of licox probes. Despite a 300-400 mmHg oxygen concentration in pure PFC solution there was no passive diffusion of oxygen into tissue during static preservation. However, when kidneys were flushed with oxygenated 5% PFC + UW, the PtO2 transiently rose from 0.0 mmHg to 20 mmHg and slowly returned to baseline 0.0 mmHg. There was only mild tubular injury with less than 5% apoptosis after 40hr cold storage in both pure PFC and 5% PFC+UW emulsion. Further molecular analysis of ischemic injury markers is pending.

*Conclusions: PFC, has unique properties to support organ preservation. Newer generation PFC is stable in an emulsion form and can function as effective oxygen carrier. These biologically inert molecules may have significant role in preservation of ECD organs in a static and dynamic setting.

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