The impact on the bioenergetic status and oxidative-mediated tissue injury of a combined protocol of hypothermic and normothermic machine perfusion using an acellular haemoglobin-based oxygen carrier: The cold-to-warm machine perfusion of the liver.

Yuri L Boteon,Hynek Mergental,Richard W Laing,Amanda Smith,Paolo Muiesan,M Thamara Pr Perera,Andrea Schlegel,Simon C Afford,Gary Reynolds,Joseph Attard,Ricky H Bhogal,Darius F Mirza,Lorraine Wallace

doi:10.1371/journal.pone.0224066

Abstract

IntroductionThe combination of hypothermic and normothermic machine perfusion (HMP+NMP) of the liver provides individual benefits of both techniques, improving the rescue of marginal organs. The aim of this study was to investigate the effect on the bioenergetic status and the oxidative-mediated tissue injury of an uninterrupted combined protocol of HMP+NMP using a single haemoglobin-based oxygen carrier (HBOC)-based perfusate.MethodsTen discarded human donor livers had either 2 hours of dual hypothermic oxygenated perfusion (D-HOPE) with sequential controlled rewarming (COR) and then NMP using the HBOC-based perfusate uninterruptedly (cold-to-warm group); or 2 hours of hypothermic oxygenated perfusion (HOPE) with an oxygen carrier-free perfusate, followed by perfusate exchange and then NMP with an HBOC-based perfusate. Markers of liver function, tissue adenosine triphosphate (ATP) levels and tissue injury were systematically assessed.ResultsThe hypothermic phase downregulated mitochondrial respiration and increased ATP levels in both groups. The cold-to-warm group presented higher arterial vascular resistance during rewarming/NMP (p = 0.03) with a trend of lower arterial flow (p = 0.09). At the end of NMP tissue expression of markers of reactive oxygen species production, oxidative injury and inflammation were comparable between the groups.ConclusionThe uninterrupted combined protocol of HMP+NMP using an HBOC-based perfusate—cold-to-warm MP—mitigated the oxidative-mediated tissue injury and enhanced hepatic energy stores, similarly to an interrupted combined protocol; however, it simplified the logistics of this combination and may favour its clinical applicability.

Highlights

The combination of hypothermic and normothermic machine perfusion (HMP+normothermic MP (NMP)) of the liver provides individual benefits of both techniques, improving the rescue of marginal organs
The uninterrupted combined protocol of hypothermic MP (HMP)+NMP using an haemoglobin-based oxygen carrier (HBOC)-based perfusate— cold-to-warm MP—mitigated the oxidative-mediated tissue injury and enhanced hepatic energy stores, to an interrupted combined protocol; it simplified the logistics of this combination and may favour its clinical applicability
Haemoglobin levels of the HBOC-perfusate were comparable between the start and end of the hypothermic phase (D-hypothermic oxygenated perfusion (HOPE)) (53.2 [44.7–65.6] vs. 52.8 [42.5–64.7] g/dL, p = 0.59)

Summary

Introduction

The combination of hypothermic and normothermic machine perfusion (HMP+NMP) of the liver provides individual benefits of both techniques, improving the rescue of marginal organs. The inability to utilise a red blood cell-based perfusate during HMP, owing to the risk of sludging [12] and haemolysis [9] at hypothermia as well as the need for an oxygen carrier during NMP, imposes the need for perfusate exchange during the perfusion process if one wishes to combine both techniques, as it was previously done by our research group [8]. This interruption in the perfusion process adds an unnecessary ischaemic time to the organs, which may hinder the implementation of the combined protocol of HMP and NMP

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