Impact of Subnormothermic Machine Perfusion Preservation in Severely Steatotic Rat Livers: A Detailed Assessment in an Isolated Setting

Abstract

The current drastic shortage of donor organs has led to acceptance of extended-criteria donors for transplantation, despite higher risk of primary nonfunction. Here, we report the impact of subnormothermic machine perfusion (SMP) preservation on the protection of >50% macrosteatotic livers. Dietary hepatic steatosis was induced in Wistar rats via 2-day fasting and subsequent 3-day re-feeding with a fat-free, carbohydrate-rich diet. This protocol induces 50-60% macrovesicular steatosis, which should be discarded when preserved via cold storage (CS). The fatty livers were retrieved and preserved for 4 h using either CS in histidine-tryptophan-ketoglutarate or SMP in polysol solution. Graft functional integrity was evaluated via oxygenated ex vivo reperfusion for 2 h at 37°C. SMP resulted in significant reductions in not only parenchymal alanine aminotransferase (p < 0.001), but also mitochondrial glutamate dehydrogenase (p < 0.001) enzyme release. Moreover, portal venous pressure (p = 0.047), tissue adenosine triphosphate (p = 0.001), bile production (p < 0.001), high-mobility group box protein-1 (p < 0.001), lipid peroxidation, and tissue glutathione were all significantly improved by SMP. Electron microscopy revealed that SMP alleviated deleterious alterations of sinusoidal microvasculature and hepatocellular mitochondria, both of which are characteristic disadvantages associated with steatosis. SMP could protect 50-60% macrosteatotic livers from preservation/reperfusion injury, and may thus represent a new means for expanding available donor pools.

Hydrogen Flush After Cold Storage as a New End‐Ischemic Ex Vivo Treatment for Liver Grafts Against Ischemia/Reperfusion Injury

“…Whole liver grafts were retrieved as detailed elsewhere . Briefly, rats were anesthetized with isoflurane (Escain, Mylan, Osaka, Japan) via a small animal anesthetizer (MK‐A110; Muromachi Kikai Co., Ltd., Tokyo, Japan).…”

Opportunities for Therapeutic Intervention During Machine Perfusion

“…Interestingly, even HMP of steatotic rat livers improves bile production, liver ATP and liver oxygen consumption in a simulated reperfusion model, when compared to steatotic livers preserved by SCS [64]. Oxygenated SNMP of rat steatotic livers improves ALT release, ATP, bile production, lipid peroxidation and tissue glutathione compared to SCS preserved steatotic rat livers [65]. In spite of improvements of steatotic liver parameters on MP [64, 65], in depth metabolomics profiling of declined human livers during oxygenated SNMP revealed that steatotic livers still replenish their ATP and uptake oxygen less than even DCD livers.…”

“…Oxygenated SNMP of rat steatotic livers improves ALT release, ATP, bile production, lipid peroxidation and tissue glutathione compared to SCS preserved steatotic rat livers [65]. In spite of improvements of steatotic liver parameters on MP [64, 65], in depth metabolomics profiling of declined human livers during oxygenated SNMP revealed that steatotic livers still replenish their ATP and uptake oxygen less than even DCD livers. Moreover, steatotic livers have significantly more arterial resistance [26].…”

Representing Subnormothermic Machine Perfusion in Fatty Livers: The Complete Picture?

“…After reading "Impact of Subnormothermic Machine Perfusion Preservation in Severely Steatotic Rat Livers: A Detailed Assessment in an Isolated Setting" by Okamura et al, we wish to bring to your attention previously published results about the use of subnormothermic machine perfusion (SMP) in marginal organs such as steatotic livers given that due consideration of such data is missing in the discussion section of this report (1). This is particularly surprising because, in 2009, an editorial published on Liver Transplantation (2) by Thomas van Gulik highlighted the protective effects of machine perfusion (MP) performed for the first time at 20°C by using fatty livers.…”