Pre- and postconditioning effects of metformin in rat donor livers

Background: Pre- or reconditioning of donor livers can improve organ quality prior to transplantation. The aim of this study was to investigate whether metformin as pre- or reconditioning agent is able to reduce preservation injury in rat donor livers and improve hepatobiliary function during ex situ normothermic machine perfusion (NMP). Methods: To study the preconditioning effects of metformin, metformin was administered via oral gavage 12 and 2 hours before the hepatectomy. To assess the reconditioning effects of metformin, in 2 other groups, metformin was added to the NMP perfusion fluid in two different concentrations (30 and 300 mg/L). In the reference group, no pre- or reconditioning was carried out. In all groups, rat donor livers were preserved for 4 hours in preservation fluid on melting ice. Thereafter, NMP was performed for viability assessment. Results: Preconditioning improved ATP production and hepatobiliary function (assessed by total bile production, biliary bilirubin and bicarbonate) and significantly lowered levels of lactate and glucose during NMP. On the other hand, metformin preconditioning did not reduce markers for hepatobiliary injury such as AST, ALT, LDH, caspase-3 activity, TBARS or biliary gamma-GT and LDH. Reconditioning with metformin did not improve hepatobiliary function or reduce injury markers during NMP. Conclusion: Preconditioning of rat donor livers with metformin improves hepatobiliary function but does not reduce preservation injury as assessed during 3 hours of NMP. Reconditioning with metformin showed no beneficial effects.