Introduction: Combination of reduced temperature and oxygenation via machine perfusion during liver allograft preservation has the potential to induce profound effects on hepatocyte bioenergetics and metabolism. The aim of this study was to evaluate changes in central carbohydrate metabolism in liver allografts subjected to SNMP. Methods: 12 porcine livers were procured and preserved for 9 hours with either SNMP or cold storage (CS). In SNMP group, livers were perfused at 21[deg]C with a novel hemoglobin-based oxygen carrier. Perfusate samples were obtained from both groups and assessed for concentrations of 173 metabolites involved in central carbohydrate metabolism. Liver biopsies were obtained every 3 hours from both groups and the expression of 25,000 genes was assessed in SNMP livers by microarrays. Results: In central carbohydrate metabolism, glucose (p<0.001), fructose (p<0.001), and pyruvate (p=0.03) were all significantly elevated in the SNMP group compared to the CS group. Among Krebs cycle intermediates, citrate (p=0.04) and alpha ketoglutarate (αKG, p=0.003) were elevated in the SNMP group, whereas succinate (p<0.001) was higher in the CS group. Intermediates and side products in the pentose phosphate metabolism pathway were uniformly higher in the SNMP group, including 6-phosphogluconate (↑2.3-fold, p=0.02), arabitol (↑20.2-fold, p=0.003), threitol (↑12.5-fold, p=0.002), and seduheptulse-7-phosphate (↑3.45-fold, p=0.04). Microarray data from the SNMP cohort revealed shifts in bioenergetic gene expression during machine perfusion. A modest reduction (0-30%) in gene expression was identified for most glycolytic, gluconeogenic, and Krebs cycle enzymes. An exception was phosphoenolpyruvate carboxykinase, which doubled in expression during SNMP (p<0.05). Among enzymes associated with glycogen metabolism, expression of phosphoglucomutase and inorganic pyrophosphatase decreased (70%) while glycogen synthase kinase had modest upregulation (120%) during machine perfusion. Conclusion: SNMP results in significant alterations in liver metabolism compared to those subjected to CS. SNMP may promote changes in gluconeogenesis, glycogenolysis, and glycogenesis pathways. In addition, alterations of key central metabolic intermediates (αKG, succinate) that affect critical enzymes involved in maintenance of epigenomic integrity as well as the hypoxia-inducible factor pathway were observed. This suggests a potential mechanism for alterations in gene expression.

CITATION INFORMATION: Banan B, Cyr A, Lopez R, Michalopoulos G, Fontes P. Alterations in Central Carbohydrate Metabolism in Porcine Liver Allografts Preserved with a Subnormothermic Machine Perfusion (SNMP) System. Am J Transplant. 2016;16 (suppl 3).

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