Conference Proceeding

Normothemic machine perfusion of liver grafts promotes the liver regeneration and inhibits tissue inflammation

Dr. Wayel Jassem,
Consultant, King's College Hospital, London, UK

In liver transplantation ischaemia / reperfusion (I/R) injury is associated with an inflammatory response, which has an impact on graft and patient outcome.

Dr. Wayel Jassem graduated from University of Ancona, Italy where he was also trained in General Surgery. He obtained an MD degree working on hepatic ischemia/re-perfusion in rodents in 1996. Between 1997 and 1999 he was a transplant Fellow at Nuffield Department of Surgery, University of Oxford, where he worked on cellular and molecular consequences of brain death on donor organs and normothermic perfusion systems for organs prior to transplantation. He moved to King’s College Hospital to be trained in liver transplantation and liver surgery. He has a PhD degree from University of London, investigating gene expression associated with ischemia and ischemic preconditioning in clinical liver transplantation. He performed the first phase one clinical trial in humans using normothermic machine perfusion in liver transplantation. Currently he is a Consultant Surgeon at King’s and his main interest is living donor liver transplantation and optimization of liver for transplantation.

Background & aim: In liver transplantation ischaemia / reperfusion (I/R) injury is associated with an inflammatory response, which has an impact on graft and patient outcome. Ex-vivo normothermic machine perfusion (NMP) to donor livers prior to transplantation has the potential to attenuate I/R injury, allowing to improve the function of transplanted livers and possibly to permit the use of more allografts. We carried out a first clinical study to assess the safety and performance of NMP in reserving liver allografts. We assessed the impact of NMP on patient / graft outcome, cellular and gene expression profiling of liver tissue and compared those with graft preserved with cod storage (CS).
Methods: All samples were obtained from liver allografts used for phase I clinical trial, using Organanox device. Liver biopsies were performed pre- and two hours post-perfusion for both NMP and CS conditions. Liver tissues were collected from 12 grafts donated after brain death (DBD) and 2 donated after cardiac death (DCD) and compared to 12 CS grafts, including 12 DBD and 2 DCD grafts, which were age and gender matched to NMP grafts. mRNA was extracted from liver tissues using Trizol reagent and gene expression was assessed using Illumina WG-ADSL array containing probes for 44,000 transcripts and the level of gene expression was evaluated by gene set enrichment analysis. The expression pattern of a group of 7 genes was quantified using real-time TaqMan PCR experiments.
Results: Median NMP time was 9.3 (3.5–18.5) h versus median cold ischaemia time of 8.9 (4.2–11.4) h. Thirty-day graft survival was similar (100% NMP vs. 97.5% control, p = 1.00). Median peak aspartate aminotransferase (AST) in the first 7 days was significantly lower in the NMP group (417 IU [84–4681]) versus (902 IU [218–8786], p = 0.03). Comparing gene expression between pre- and post-reperfusion biopsies, 398 genes in NMP and 382 in CS showed significant increased expression. Among these genes, 153 were common in both conditions. Decreased gene expression was seen in 276 genes in NMP grafts and 160 CS grafts, only 36 genes were in common. Genes upregulated after NMP were mainly those involved in tissue regeneration, tissue growth/repair and those involved in control of inflammation. In contrast, upregulated genes in CS were mainly those implicated in inflammation, apotosis and activation of coagulation. Expression pattern of a set of 7 genes was defined by qPCR: IRF1 was decreased, levels of IL-1 and ICAM-1 post-perfusion were lower in NMP grafts compared to CS grafts. There was no difference in gene expression level for IL-10, IFNg, SOCS1 and TGF-b.
Conclusion: 1) grafts preserved with NMP has lower pick of AST, indicating less tissue damage 2) The gene expression pattern is significantly different between NMP and CS liver grafts; 3) at an early stage post-perfusion, NMP promotes tissue repairing/generation and controls inflammation process; 4) long term benefit of NMP should be defined in future investigation.

Published: 28 April 2017