Predictor parameters of liver viability during porcine normothermic ex situ liver perfusion in a model of liver transplantation with marginal grafts.

Normothermic ex situ liver perfusion (NEsLP) offers the opportunity to assess biomarkers of graft function and injury. We investigated NEsLP parameters (biomarkers and markers) for the assessment of liver viability in a porcine transplantation model. Grafts from heart-beating donors (HBD), and from donors with 30 minutes (donation after cardiac death [DCD]30'), 70 minutes (DCD70'), and 120 minutes (DCD120') of warm ischemia were studied. The HBD, DCD30', and DCD70'-groups had 100% survival. In contrast, 70% developed primary nonfunction (PNF) and died in the DCD120'-group. Hepatocellular function during NEsLP showed low lactate (≤1.1 mmol/L) in all the groups except the DCD120'-group (>2 mmol/L) at 4 hours of perfusion (P = .04). The fold-urea increase was significantly lower in the DCD120'-group (≤0.4) compared to the other groups (≥0.65) (P = .01). As for cholangiocyte function, bile/perfusate glucose ratio was significantly lower (<0.6) in all the groups except the DCD120'-group (≥0.9) after 3 hours of perfusion (<0.01). Bile/perfusate Na+ ratio was significantly higher (≥1.2) after 3 hours of perfusion in all the groups except for the DCD120'-group (≤1) (P < .01). Three hours after transplantation, the DCD120'-group had a significantly higher international normalized ratio (>5) compared to the rest of the groups (≤1.9) (P = .02). Rocuronium levels were higher at all the time-points in the animals that developed PNF during NEsLP and after transplantation. This study demonstrates that biomarkers and markers of hepatocellular and cholangiocyte function during NEsLP correlate with the degree of ischemic injury and posttransplant function.

Elevated Preoperative Serum Bilirubin Improves Reperfusion Injury and Survival Postliver Transplantation.

BACKGROUND: The cytoprotective effects of hemeoxygenase-1 and its product biliverdin/bilirubin are widely acknowledged in experimental transplant medicine. However, its potentially beneficial effect during organ reperfusion is not established. METHODS: In a matched study, we compared markers of reperfusion injury (alanine aminotransferase/aspartate aminotransferase) and transplantation outcome (complication rates, liver function, and survival) between recipient groups with "normal" versus "increased" preoperative bilirubin values. Groups were matched for donor and recipient age, liver disease, year of transplantation, and recipient's preoperative condition (modified model for end-stage liver disease score excluding bilirubin). RESULTS: The postoperative transaminase peak was significantly higher when comparing the "normal" to the "increased" bilirubin group (maximum aspartate aminotransferase "normal" 2013 [325-13 210] U/L vs "increased" 1360 [221-15 460] U/L, P = 0.006; maximum alanine aminotransferase "normal" 1151 [82-6595] U/L vs "increased" 820 [66-5382] U/L, P = 0.01). Grafts in the "increased" bilirubin group had faster recovery of graft function with faster decrease in international normalized ratio at days 3 and 7 posttransplantation in the "increased" vs "normal" bilirubin group. Although long-term functional parameters (international normalized ratio and bilirubin posttransplantation) as well as surgical and biliary complication rates were similar in both groups, 1-year survival rates were significantly higher in the group with increased preoperative bilirubin (graft survival, "normal" 86% vs "increased" 97%; P = 0.006). CONCLUSIONS: Increased bilirubin levels of liver graft recipients before transplantation are associated with reduced reperfusion injury and improved survival after transplantation.