Application of Perfusate With Human-Derived Oxygen Carrier Solution Under Subnormothermic Machine Perfusion for Donation After Cardiac Death Liver Grafts in Pigs.

Oxygenation is necessary for aerobic metabolism, which maintains adenosine triphosphate within the graft organ. In recent years, some studies have demonstrated that subnormothermic machine perfusion (SNMP) with hemoglobin-based oxygen carriers has the potential to improve oxygen metabolism. OBJECTIVE: The aim of this study was to evaluate the effectiveness of perfusate with human-derived hemoglobin vesicles (HbV) under SNMP in a pig model of donation after cardiac death. MATERIALS AND METHODS: In this study, pig livers were procured with a warm ischemic time of 60 minutes and were preserved in 3 groups for 240 minutes. The preservation conditions were as follows: 4°C cold storage (Group 1); SNMP with University of Wisconsin perfusate alone (Group 2); and SNMP (21°C) with University of Wisconsin solution and HbV (hemoglobin, 0.6 mg/dL) perfusate (Group 3). All livers were perfused for 120 minutes using pig autologous blood machine perfusion (reperfusion phase). We investigated the aspartate transaminase level and hemodynamics (portal vein resistance and oxygen consumption) in the preservation and reperfusion phases. A histologic study (hematoxylin-eosin staining) was performed after 240 minutes of preservation. RESULTS: The portal vein resistance of Group 3 was not increased in comparison with Group 2. During preservation, the oxygen consumption of Group 3 was higher than that of Group 2. However, the level of aspartate transaminase did not differ between Groups 2 and 3. CONCLUSION: The present study revealed that perfusate with HbV increased the oxygen consumption of the donor liver during SNMP.

Ex Vivo Reperfusion Model to Evaluate Utility of Machine Preservation for Porcine Liver Donated After Cardiac Death.

BACKGROUND: Machine perfusion (MP) techniques are expected to prove useful for preserving the organ viability and recovering organ function for organ transplantation. Furthermore, an accurate assessment of organ viability using MP is important for expanding the donor criteria. In this study, an ex vivo reperfusion model (ERM) simulating transplantation using diluted autologous blood under normothermic conditions was evaluated for its utility of MP under subnormothermic conditions for livers donated after cardiac death (DCD). METHODS: The liver preservation methods for DCD porcine livers were evaluated using the ERM. This investigation was performed using a novel perfusion system developed by our research group. Porcine livers were procured with a warm ischemia time (WIT) of 60 minutes. The organs were then preserved using subnormothemic machine perfusion (SNMP) or static cold storage (CS) for 4 hours. We also compared these tissues with SNMP livers procured under a WIT of 0 minutes. After the preservation, the livers were reperfused for 2 hours using the ERM with diluted autologous blood oxygenated by a membrane oxygenator under NMP conditions. Reperfusion was evaluated based on perfusion flow dynamics and outflow of deviating enzymes. RESULTS: In the early stages of reperfusion, pressure in the blood vessels increased sharply in the CS group. Furthermore, the amount of aspartate aminotransferase accumulation was lower in the SNMP group than in the other groups. These results suggest ischemia-reperfusion injury is suppressed in SNMP conditions. CONCLUSION: An ERM has use in evaluating the utility of MP for the DCD liver.

Optimum Perfusate Volume of Purified Subnormothermic Machine Perfusion for Porcine Liver Donated After Cardiac Death.

INTRODUCTION: Subnormothermic machine perfusion (SNMP) shows some advantages for the preservation of grafts donated after cardiac death (DCD) and improvements in machine perfusion (MP) technology are important to enhance organ preservation outcomes for liver transplantation. In this study, we focused on purified subnormothermic machine perfusion (PSNMP) and volumes of perfusate removed to substitute for purification and replaced by modified University of Wisconsin-gluconate after the start of perfusion and investigated, in particular, the optimum perfusate purification volume. Several purification volumes under SNMP were compared. In addition, the perfusate purification during MP was indicated as a potential technique to enhance the organ quality of DCD grafts and extended-criteria donors. METHODS: The PSNMP at several volumes (0.5 L, 1.5 L, and 3 L) were compared with regular SNMP without any purification treatment (untreated control). In the PSNMP group, all perfusate was removed to substitute for purification of the perfusate by modified University of Wisconsin-gluconate solution after the start of perfusion. After removing the perfusate, new perfusate with the same components was perfused to preserve the porcine livers obtained under warm ischemia for 60 minutes using SNMP at 22°C porcine liver for 4 hours. RESULTS: The concentrations of aspartate aminotransferase and lactate dehydrogenase in the untreated group were significantly higher during perfusion compared to those of the intervention group. There are no significant differences among the volume conditions of the purification groups. CONCLUSIONS: The optimal volume of perfusate purification was confirmed with a simple experimental comparison between untreated and PSNMP conditions.

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.

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.