Scanning Electron Microscopy Findings of Machine Perfused Liver Graft After Warm Ischemia Between Hypothermic and Rewarming Machine Perfusion in Pigs.

BACKGROUND: The 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. METHODS: Porcine 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. RESULTS: A 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. CONCLUSIONS: An 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.

Applicability of Combined Use of Extracorporeal Support and Temperature-Controlled Machine Perfusion Preservation for Liver Procurement of Donors After Cardiac Death in Pigs.

BACKGROUND: The use of grafts from donors after cardiac death (DCD) would greatly contribute to the expansion of the donor organ pool. The objective of this study is to determine the benefits of extracorporeal membrane oxygenation (ECMO) and subnormothermic machine perfusion (MP) with rewarming in a large animal model of DCD liver. METHODS: After cardiac arrest, the abdominal aorta and the inferior vena cava were cannulated and connected to an ECMO circuit. Porcine livers were perfused in situ with ECMO at 22°C for 60 minutes after 60 minutes of cardiac death. Then the livers were perfused for 4 hours by MP as a graft viability test. In group 1, non-in situ ECMO and grafts were preserved hypothermic MP. In group 2, non-in situ ECMO and grafts were preserved subnormothermic rewarming MP. In group 3, we used ECMO and subnormothermic rewarming MP. To assess potential methods and effect, effluent enzymes were measured. Portal vein and hepatic artery pressure during MP were evaluated. RESULTS: Effluent enzyme of AST, alanine aminotransferase and LDH as viability markers were significantly low (aspartate aminotransferase, 2899, 2292, and 972 IU/L; alanine aminotransferase, 134, 140, and 72 IU/L; and lactate dehydrogenase, 4354, 4455, and 1855 IU/L in each group, respectively). Portal vein and hepatic artery pressure during preservation came down smoothly in group 3 compared with group 1. CONCLUSIONS: The combined use of in situ subnormothermic ECMO and machine preservation with rewarming is more essential for the recovery and resuscitating function of DCD liver grafts.

Regulated Oxygenation of Rewarming Machine Perfusion for Porcine Donation After Cardiac Death Liver Transplantation.

INTRODUCTION: Machine perfusion (MP) is particularly expected to preserve and resuscitate an organ obtained from extended criteria donors or donation after cardiac death to expand the donated organ pool for organ transplantation. This method requires to be investigated an optimal preservation condition. The aim of this study is investigation of the optimal oxygenation conditions under rewarming MP (RMP). METHODS: Porcine livers were perfused with an RMP system developed by our research group. All livers were procured under warm ischemia time of 60 minutes, and preserved in static cold storage for 2 hours, and perfused for 2 hours using the RMP. For group 1, the livers were supplied with oxygen constantly through perfusate. For group 2, the livers were supplied with oxygen increasingly with controlling flow rates and oxygen concentration. Effluent enzymes were obtained during perfusion preservation. RESULTS: The average levels of alanine aminotransferase were lower in group 2 than in group 1 during RMP, and also decreasing the hepatic artery pressures after 60 minutes. CONCLUSIONS: Regulated oxygenation of RMP has possibility to improve the graft preservation for liver transplantation.

Subnormothermic Machine Perfusion Preservation With Rewarming for Donation After Cardiac Death Liver Grafts in Pigs.

BACKGROUND: The use of grafts from donors after cardiac death (DCD) would greatly contribute to the expansion of the donor organ pool. However, the implementation of such a strategy requires the development of novel preservation methods to recover from changes owing to warm ischemia. The aim of this study was to evaluate the effectiveness of subnormothermic machine perfusion (MP) preservation with rewarming for porcine DCD liver grafts for transplantation. METHODS: Porcine livers were perfused with newly developed MP system. The livers were perfused for 4 hours with modified University of Wisconsin gluconate solution. Group 1 grafts were preserved with no warm ischemia time (WIT) and hypothermic MP (HMP) for 4 hours. Group 2 grafts were preserved with WIT 60 minutes and HMP for 4 hours. Group 3 grafts were preserved with WIT 60 minutes and rewarming up to 25°C by MP (RMP) for 4 hours. RESULTS: The aspartate aminotransferase and lactate dehydrogenase in the effluent maintained at lower level in group 3 compared with group 2. However, tissue ATP levels did not recover in groups 2 and 3. Histologically, the fatty degenerate and swelling of the hepatocyte was slightly seen in all groups. The normal structure of the hepatocellular cords, the bile duct and the sinusoid endothelium were preserved in all groups. CONCLUSIONS: Potentially, subnormothermic preservation with rewarming is expected to help the recovery of function for DCD liver grafts.