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Normothermic ex vivo kidney perfusion (NEVKP) has demonstrated superior outcomes for donation-after-cardiovascular death grafts compared with static cold storage (SCS). To determine the mechanisms responsible for this, we performed an unbiased genome-wide microarray analysis., Methods: Kidneys from 30-kg Yorkshire pigs were subjected to 30 min of warm ischemia followed by 8 h of NEVKP or SCS, or no storage, before autotransplantation. mRNA expression was analyzed on renal biopsies on postoperative day 3. Gene set enrichment analysis was performed using hallmark gene sets, Gene Ontology, and pathway analysis., Results: The gene expression profile of NEVKP-stored grafts closely resembled no storage kidneys. Gene set enrichment analysis demonstrated enrichment of fatty acid metabolism and oxidative phosphorylation following NEVKP, whereas SCS-enriched gene sets were related to mitosis, cell cycle checkpoint, and reactive oxygen species ( q  < 0.05). Pathway analysis demonstrated enrichment of lipid oxidation/metabolism, the Krebs cycle, and pyruvate metabolism in NEVKP compared with SCS ( q  < 0.05). Comparison of our findings with external data sets of renal ischemia-reperfusion injury revealed that SCS-stored grafts demonstrated similar gene expression profiles to ischemia-reperfusion injury, whereas the profile of NEVKP-stored grafts resembled recovered kidneys., Conclusions: Increased transcripts of key mitochondrial metabolic pathways following NEVKP storage may account for improved donation-after-cardiovascular death graft function, compared with SCS, which promoted expression of genes typically perturbed during IRI., Competing Interests: The authors declare no funding or conflicts of interest., (Copyright © 2021 The Author(s). Transplantation Direct. Published by Wolters Kluwer Health, Inc.)

Background: Human albumin/dextran (HA-D), bovine-gelatin (BG), and packed red blood cells plus plasma have been used in European and North-American clinical trials of normothermic ex situ liver perfusion (NEsLP). We compared the effects of these perfusates in a porcine model during NEsLP and after transplantation., Methods: Porcine livers were retrieved 30 minutes after circulatory death. After 5 hours of NEsLP, grafts were transplanted. Three groups (n = 6) were assessed (HA-D vs BG vs whole blood [WB]). One group of static cold storage (SCS) was evaluated for comparison with the perfusion groups. Hemodynamic variables, liver and endothelial injury, and function were assessed during NEsLP and posttransplantation., Results: Hepatic artery flow was higher since the beginning of NEsLP in the HA-D group (HA-D, 238 ± 90 mL/min vs BG, 97 ± 33 mL/min vs WB, 148 ± 49 mL/min; P = 0.01). Hyaluronic acid was lower in the HA-D at the end of perfusion (HA-D, 16.28 ± 7.59 ng/μL vs BG, 76.05 ± 15.30 ng/μL vs WB, 114 ± 46 ng/μL; P < 0.001). After transplant, aspartate aminotransferase was decreased in the HA-D group when compared with the rest of the groups (HA-D, 444 ± 226 IU/L vs BG, 1033 ± 694 IU/L vs WB, 616 ± 444 IU/L vs SCS, 2235 ± 1878 IU/L). At 5 hours after transplant, lactate was lower in the HA-D group (HA-D, 3.88 ± 1.49 mmol/L vs BG, 7.79 ± 2.68 mmol/L vs WB, 8.16 ± 3.86 mmol/L vs SCS, 9.06 ± 3.54 mmol/L; P = 0.04). International Normalized Ratio was improved in HA-D group compared to the rest of the groups (HA-D, 1.23 ± 0.30 vs BG, 1.63 ± 0.20 vs WB, 1.50 ± 0.31 vs SCS, 1.97 ± 1.55; P = 0.03) after transplantation. In contrast, BG displayed lower aspartate aminotransferase levels during NEsLP (HA-D, 183 ± 53 IU/L vs BG, 142 ± 52 IU/L vs WB, 285 ± 74 IU/L; P = 0.01) and less cleaved-caspase-3 staining (HA-D, 2.05 ± 0.73% vs BG, 0.95 ± 1.14% vs WB, 1.74 ± 0.54% vs SCS, 7.95 ± 2.38%) compared with the other groups. On the other hand, the bile from the WB showed higher pH (HA-D, 7.54 ± 0.11 vs BG, 7.34 ± 0.37 vs WB, 7.59 ± 0.18) and lower glucose levels (HA-D, 0.38 ± 0.75 mmol/L vs BG, 1.42 ± 1.75 mmol/L vs WB, 0 ± 0 mmol/L) by the end of perfusion., Conclusions: Overall HA-D displayed more physiologic conditions during NEsLP that were reflected in less graft injury and improved liver function and survival after transplantation. Optimization of the perfusates based on the beneficial effects found with these different solutions would potentially improve further the outcomes through the use of NEsLP in marginal grafts., Competing Interests: The authors declare no conflicts of interest.

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., Competing Interests: The authors declare no funding or conflicts of interest.