Indicators of Liver Viability in the Ex Vivo Perfused Human Liver.

Abstract

Machine perfusion of the liver is rapidly gaining support for the recovery and preservation of grafts injured by long warm ischemia (WI). A major advantage of machine perfusion at warm temperatures is the ability to assess the viability of the liver pre-transplantation. However, the best indicators need to be identified to accurately assess the liver during perfusion. To this end, we perfused 20 human livers discarded for transplantation with varying durations of warm ischemia (range 14-54 minutes) in our subnormothermic perfusion system. We monitored the liver by assessment of blood gas analysis, bile flow, biochemical markers of function (albumin, urea) and injury (alanine aminotransferase, alkaline phosphatase), tissue analysis (ATP), clearance of indocyanine green (ICG), and (electron-)microscopy. These parameters were correlated to characteristics of the donor and WI of the liver. We show here that metabolic and liver function parameters are sustained or improved during perfusion, with an increase in oxygen consumption, albumin and urea output and overall sustained bile production. Minimal injury was observed biochemically or microscopically. ATP content of the liver tissue improved significantly (61.1 to 204.3 p=0.012). ATP content showed a good correlation with WIT (r2=.83, p=.0045). As ATP measurement requires tissue biopsy non-invasive and real-time parameter are preferred. Not the total production of bile, but whether bile production increased during perfusion correlated best with the low WIT (p<0.006)(Figure). A positive correlation with WIT was also found between the release of alanine aminotransferase (ALT) (r2=.58, p=.016) and clearance of ICG (r2=.95, p=.002). In conclusion, ATP content, sustained bile production and ALT and clearance of ICG are best correlated to WIT and may be useful as indicators of liver quality. Ongoing work aims to formulate predictive scores using these and other parameters of viability that can predict transplant outcome.Figure: No Caption available.DISCLOSURES:Izamis, M.: Other, Author of patent, A patent exists including the technology described. Uygun, K.: Other, Author on patent, A patent exists including the technology described.