Improving the function of liver grafts exposed to warm ischemia by the leuven drug protocol: Exploring the molecular basis by microarray

BACKGROUND DATA: Livers that have been exposed to a period of warm ischemia (WI) prior to transplantation (Tx) have an increased risk of primary non function (PNF), graft dysfunction and ischemic type biliary strictures all associated with Ischemia Reperfusion Injury (IRI). Our multifactorial biological modulation approach (Leuven Drug Protocol [LDP]) has been shown to eliminate PNF, improve liver function, reduce bile salt toxicity and increase recipient survival after transplantation of WI/IRI-damaged porcine livers. AIM: The identification of the molecular mechanisms responsible for the hepatoprotective effect of the LDP. METHODS: Porcine livers were exposed to 45' WI, cold stored (4hrs), transplanted and either modulated (LDP-group, n = 3) or not (controls, n = 4). In the LDP-group, donor livers were flushed with streptokinase and epoprostenol prior to cold perfusion; recipients received IV glycine, α1-acid-glycoprotein, MAPKinase-inhibitor FR167653, α-tocopherol, glutathione and apotransferrine upon graft reperfusion. Liver samples were taken before WI and 1 hour after reperfusion. Gene expression was determined by microarray and molecular pathways and key regulatory genes were identified. RESULTS: The number of differentially expressed genes between baseline and 1 hr after reperfusion was 686 in the LDP-group and 325 in controls. The extra genes in the LDP group belonged predominantly to molecular pathways related to cytokine activity, apoptosis and cell proliferation. We identified 7 genes (IL6, IL8, JUN, MMP1, PTGS2/COX2, SERPINE1 and STAT3) that were suppressed in the LDP group. These genes could be linked - in part - to the drugs administered. New potential drugs targets were identified based on (i) genes induced in the control group but left unaffected in the LDP group and (ii) by predicted interactions according to literature. CONCLUSIONS: The Leuven Drug Protocol primarily results in the suppression of inflammation regulating genes in IRI. Furthermore, the microarray technique helped to identify additional gene targets. Liver Transpl, 2011. © 2011 AASLD.