Bootcongres

Background Donation after circulatory death (DCD) inevitably results in warm ischemic damage which varies in its extent and affects early graft function and -survival due to an increased risk of ischemic cholantiopathy. Hypothermic machine perfusion (HMP) may optimize DCD graft quality and allows objective assessment of graft quality and viability before transplantation. Recently, human hepatocyte and cholangiocyte-derived miRNAs (HDmiRs & CDmiRs) measured during static cold storage were shown to be predictive markers for biliary injury. The aim of this study was to investigate whether HDmiRs and CDmiRs can be measured in perfusates during HMP to assess graft injury in a porcine DCD model. Methods Porcine livers were subjected to warm ischemia (WI; 0-120 min) and subsequently HMP preserved for 4h. Then, normothermic perfusion was applied for 2h to assess graft function. Perfusates were collected during graft HMP and analysed on AST levels and by RT-qPCR on HDmiR-122 and CDmiR-222. Biopsies collected during HMP and normothermic perfusion were scored for morphology. Results Cholangiocyte abundance of CDmiR-222 was confirmed by comparing expresson levels in n=24 liver biopsies and n=8 extrahepatic bile duct biopsies (8-fold enriched). Both HDmiRs and CDmiRs were detectable in perfusates during HMP. At start of HMP, levels of AST and HDmiR-122 were significantly elevated in grafts subjected to 60 min WI compared to livers that were not subjected to WI (P<0.05). During HMP, perfusate levels of AST gradually increased, but after 1h of HMP levels of AST could not significantly discriminate between grafts that were subjected to various WI times. In contrast, HDmiR-122 levels after 1h HMP showed better discriminative power between grafts with various times of WI (P<0.01) and stronger correlated with hepatocyte morphology in paired biopsy samples taken during HMP (P=0.005, R=0.359). After 1h of HMP, levels of CDmiR-222 showed best discriminative capacity for WI time (P≤0.01). 

Conclusion This study demonstrates the superior discriminative power of released HDmiRs and CDmiRs in perfusates during HMP of DCD liver grafts, compared to conventional transaminase levels to assess warm ischemic injury. In particular the capacity of CDmiR-222 to sensitively distinguish grafts with various WI times corresponds with the fact that cholangiocytes are less tolerant for WI and indicates that CDmiRs are potential markers to evaluate the degree of biliary injury in DCD grafts.