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Free keywords:
FMN
Complex I
Hypothermic oxygenated perfusion
Normothermic oxygenated perfusion
Liver transplantation
Abstract:
Background:
Mitochondrial succinate accumulation has been suggested as key event for ischemia reperfusioninjury in mice. No specific data are however available on behavior of liver mitochondria duringex situmachine perfusion in clinical transplant models.
Methods:
We investigated mitochondrial metabolism of isolated perfused rat livers before transplantation.Livers were exposed to warm and cold ischemia to simulate donation after circulatory death (DCD) and organtransport. Subsequently, livers were perfused with oxygenated Belzer-MPS for 1h, at hypothermic or normo-thermic conditions. Various experiments were performed with supplemented succinate and/or mitochon-drial inhibitors. The perfusate, liver tissues, and isolated mitochondria were analyzed by mass-spectroscopyandfluorimetry. Additionally, rat DCD livers were transplanted after 1h hypothermic or normothermic oxy-genated perfusion. In parallel, perfusate samples were analysed during HOPE-treatment of human DCD liversbefore transplantation.
Findings:
Succinate exposure during rat liver perfusion triggered a dose-dependent release of mitochondrialFlavin-Mononucleotide (FMN) and NADH in perfusates under normothermic conditions. In contrast, perfus-ate FMN was 3-8 fold lower under hypothermic conditions, suggesting less mitochondrial injury during coldre-oxygenation compared to normothermic conditions. HOPE-treatment induced a mitochondrial reprog-ramming with uploading of the nucleotide pool and effective succinate metabolism. This resulted in a clearsuperiority after liver transplantation compared to normothermic perfusion. Finally, the degree of mitochon-drial injury during HOPE of human DCD livers, quantified by perfusate FMN and NADH, was predictive forliver function.
Interpretation:
Mitochondrial injury determines outcome of transplanted rodent and human livers. Hypothermicoxygenated perfusion improves mitochondrial function, and allows viability assessment of liver grafts beforeimplantation.
Funding:
detailed information can be found in Acknowledgments.
