NIV Congres

Background and aims Ischemia and reperfusion injury (IRI) of the liver graft is an important factor determining long-term transplantation success. At different stages of graft procurement, transportation and directly post-engraftment, ischemic injury of the graft can occur. Due to a lack of biomarkers however, it remains difficult to assess graft quality and the degree of ischemic injury during liver transplantation. Recently, hepatocyte and cholangiocyte-derived microRNAs (HDmiRs and CDmiRs) have been identified as sensitive markers for liver injury in patients’ serum after liver transplantation. The aim of this study was to investigate whether HDmiRs and CDmiRs in serum can accurately assess the amount of hepatic IRI in a porcine model.

Methods Ten female Yorkshire pigs were subjected to hepatic IRI using a total vascular exclusion model by clamping the hepatic artery, portal vein and hepatic veins for 30 minutes. Two vascular probes continuously monitored the absence of blood flow during ischemia. Serum and liver biopsies were collected prior to ischemia and up to 90 minutes after reperfusion. Samples were tested for levels of AST, ALT, gamma-GT, total bilirubin and LDH. Through real-time qPCR serum samples were analysed for HDmiRs HDmiR-122 & HDmiR-148a, and CDmiRs CDmiR-30e & CDmiR-222. As control miRNAs, the muscle-derived miR-133a and blood-derived miR-191 were analysed.

Results Both HDmiRs and CDmiRs were detectable in porcine serum. Of the conventional injury markers, only AST showed an elevation in serum with a maximum of three-fold after reperfusion (64 ± 30 U/L at baseline vs. 64 ± 10 U/L at reperfusion and 135 ± 50 at 60 minutes after reperfusion, P=0.012). In contrast to this, serum HDmiR- and CDmiR-levels were already significantly higher at time of reperfusion (4.9 ± 3.7 fold change, P=0.02) and their levels remained elevated longer after reperfusion compared to AST, reaching up to 90-fold (32.7 ± 29.9 fold change). MiRNA-191 and miR-133a, which served as control miRNAs, showed neither significant changes after ischemia/reperfusion, suggesting that our findings are related to hepatic IRI.

Conclusion In this study we demonstrate that microRNAs are an early and sensitive serum marker for hepatic IRI in pigs. To further investigate the correlation between miRNA release in serum and tissue damage, pre- and post-reperfusion biopsies will be analysed on liver and bile duct histology and miRNA expression levels.