13th Congress of the International Society for Organ Donation and Procurement (ISODP)Experimental modelsScanning Electron Microscopy Findings of Machine Perfused Liver Graft After Warm Ischemia Between Hypothermic and Rewarming Machine Perfusion in Pigs

•The use of grafts from donors after cardiac death would greatly contribute to the expansion of the donor organ pool.•A novel machine perfusion preservation system to control the perfusate temperatures from hypothermic to subnormothermic conditions is presented.•Scanning electron microscopy of tissue samples from a liver biopsy can clearly show the internal structures of intracellular organelles compared to transmission electron microscopy.

BackgroundThe shortage of organ donors is a universal problem. Use of grafts from donors after cardiac death would greatly contribute to the expansion of the donor organ pool. The two major methods of preservation are cold storage and machine perfusion (MP) preservation, and each has its own advantages. Several studies have reported the relative merits of MP for the preservation for grafts from donors after cardiac death. In this study, we used scanning electron microscopy (SEM) to assess the damage to the liver between hypothermic and rewarming preservation conditions.MethodsPorcine livers were perfused with a newly developed MP system. The livers were perfused for 4 hours with a modified University of Wisconsin solution-gluconate solution. In group 1, grafts were preserved with warm ischemic time for 60 minutes and hypothermic machine perfusion (HMP) for 4 hours. In group 2, grafts were preserved with warn ischemic time for 60 minutes and had rewarming up to 22°C by MP (RMP) for 4 hours.ResultsA significant enlargement of the mitochondria were observed in both the HMP and RMP groups under higher magnification, Additionally, vacuoles appeared occasionally in hepatocytes in the RMP for 4 hours group, but not in the HMP for 4 hours group.ConclusionsAn analysis by scanning electron microscope appears to be useful to evaluate the levels of damage of hepatocytes compared with transmission electron microscopy, and further study is needed to analyze the significance of the appearance of swelling of mitochondria and vacuolization during preservation.