The economic impact of machine perfusion technology in liver transplantation

Introduction: Several clinical studies have demonstrated the safety, feasibility, and efficacy of machine perfusion in liver transplantation, although its economic outcomes are still underexplored. This review aimed to examine the costs related to machine perfusion and its associated outcomes.Methods: Expert opinion of several groups representing different machine perfusion modalities. Critical analysis of the published literature reporting the economic outcomes of the most used techniques of machine perfusion in liver transplantation (normothermic and hypothermic ex situ machine perfusion and in situ normothermic regional perfusion).Results: Machine perfusion costs include disposable components of the perfusion device, perfusate components, personnel and facility fees, and depreciation of the perfusion device or device lease fee. The limited current literature suggests that although this upfront cost varies between perfusion modalities, its use is highly likely to be cost-effective. Optimization of the donor liver utilization rate, local conditions of transplant programs (long waiting list times and higher MELD scores), a decreased rate of complications, changes in logistics, and length of hospital stay are potential cost savings points that must highlight the expected benefits of this intervention. An additional unaccounted factor is that machine perfusion optimizing donor organ utilization allows patients to be transplanted earlier, avoiding clinical deterioration while on the waiting list and the costs associated with hospital admissions and other required procedures.Conclusion: So far, the clinical benefits have guided machine perfusion implementation in liver transplantation. Albeit there is data suggesting the economic benefit of the technique, further investigation of its costs to healthcare systems and society and associated outcomes is needed.</p

Development of Clinical Criteria for Functional Assessment to Predict Primary Nonfunction of High-Risk Livers Using Normothermic Machine Perfusion

Increased use of high-risk allografts is critical to meet the demand for liver transplantation. We aimed to identify criteria predicting viability of organs, currently declined for clinical transplantation, using functional assessment during normothermic machine perfusion (NMP). Twelve discarded human livers were subjected to NMP following static cold storage. Livers were perfused with a packed red cell-based fluid at 37°C for 6 hours. Multilevel statistical models for repeated measures were employed to investigate the trend of perfusate blood gas profiles and vascular flow characteristics over time and the effect of lactate-clearing (LC) and non-lactate-clearing (non-LC) ability of the livers. The relationship of lactate clearance capability with bile production and histological and molecular findings were also examined. After 2 hours of perfusion, median lactate concentrations were 3.0 and 14.6 mmol/L in the LC and non-LC groups, respectively. LC livers produced more bile and maintained a stable perfusate pH and vascular flow &gt;150 and 500 mL/minute through the hepatic artery and portal vein, respectively. Histology revealed discrepancies between subjectively discarded livers compared with objective findings. There were minimal morphological changes in the LC group, whereas non-LC livers often showed hepatocellular injury and reduced glycogen deposition. Adenosine triphosphate levels in the LC group increased compared with the non-LC livers. We propose composite viability criteria consisting of lactate clearance, pH maintenance, bile production, vascular flow patterns, and liver macroscopic appearance. These have been tested successfully in clinical transplantation. In conclusion, NMP allows an objective assessment of liver function that may reduce the risk and permit use of currently unused high-risk livers.</p

Discarded livers tested by normothermic machine perfusion in the VITTAL trial:Secondary end points and 5-year outcomes

Normothermic machine perfusion (NMP) enables pretransplant assessment of high-risk donor livers. The VITTAL trial demonstrated that 71% of the currently discarded organs could be transplanted with 100% 90-day patient and graft survivals. Here, we report secondary end points and 5-year outcomes of this prospective, open-label, phase 2 adaptive single-arm study. The patient and graft survivals at 60 months were 82% and 72%, respectively. Four patients lost their graft due to nonanastomotic biliary strictures, one caused by hepatic artery thrombosis in a liver donated following brain death, and 3 in elderly livers donated after circulatory death (DCD), which all clinically manifested within 6 months after transplantation. There were no late graft losses for other reasons. All the 4 patients who died during the study follow-up had functioning grafts. Nonanastomotic biliary strictures developed in donated after circulatory death livers that failed to produce bile with pH &gt;7.65 and bicarbonate levels &gt;25 mmol/L. Histological assessment in these livers revealed high bile duct injury scores characterized by arterial medial necrosis. The quality of life at 6 months significantly improved in all but 4 patients suffering from nonanastomotic biliary strictures. This first report of long-term outcomes of high-risk livers assessed by normothermic machine perfusion demonstrated excellent 5-year survival without adverse effects in all organs functioning beyond 1 year (ClinicalTrials.gov number NCT02740608).</p

Manipulation of lipid metabolism during normothermic machine perfusion: Effect of defatting therapies on donor liver functional recovery.

BACKGROUND Strategies to increase steatotic donor livers' utilisation are required to tackle the mortality on the transplant waiting list. We aimed to test the efficacy of pharmacological enhancement of the lipid metabolism of human livers during ex-situ normothermic machine perfusion to promote defatting and improve the functional recovery of the organs. METHODS Ten livers discarded because of steatosis were allocated to a defatting group that had the perfusate supplemented with a combination of drugs to enhance lipid metabolism or a control group that received perfusion fluid with vehicle only. Steatosis was assessed using tissue homogenate and histological analysis. Markers for lipid oxidation and solubilisation, oxidative injury, inflammation and biliary function were evaluated by ELISA, immunohistochemistry and in-gel protein detection. RESULTS Treatment reduced tissue triglycerides by 38% and macrovesicular steatosis by 40% over 6 hours. This effect was driven by increased solubilisation of triglycerides (p=0.04); and mitochondrial oxidation as assessed by increased ketogenesis (p=0.008) and adenosine triphosphate synthesis (p=0.01) associated with raised levels of the enzymes ACOX-1, CPT1A and acetyl-CoA synthetase. Concomitantly, defatted livers exhibited enhanced metabolic functional parameters such as urea production (p=0.03), lower vascular resistance, lower release of alanine aminotransferase (p=0.049) and higher bile production (p=0.008) with a higher bile pH (p=0.03). The treatment downregulated the expression of markers for oxidative injury, activation of immune cells (CD-14; CD-11b) and reduced the release of inflammatory cytokines in the perfusate (TNF-α; IL-1β). CONCLUSION Pharmacological enhancement of intracellular lipid metabolism during normothermic machine perfusion decreased the lipid content of human livers within 6 hours. It also improved the intracellular metabolic support to the organs leading to successful functional recovery and decreased expression of markers of reperfusion injury. This article is protected by copyright. All rights reserved

Assessment of the cytotoxicity of the defatting cocktail to human cells of the liver via MTT assay.

<p>Panel A: the toxicity of the defatting cocktail was tested in primary human hepatocytes and results showed a significant improvement of 11% in viability of the defatting treatment group compared with the fatty vehicle control group. Panel B: Treatment of human intra-hepatic endothelial cells (HIEC) with the drugs had no effect on cell viability compared with the control groups. Panel C: treatment of cholangiocytes with the defatting cocktail did not demonstrate any cytotoxic effect to the cells and indicated a slight improvement in viability compared to the control groups. Panels D and E: Phase contrast microscopy showing representative images of HIEC (Panel D) and cholangiocytes (Panel E) at different time points. No gross modifications in cell integrity were observed in either cell type which was consistent and supportive of the MTT data. Data report the median of three separate experiments performed in quadruplicate and errors bars the interquartile range. Comparisons performed using two-tailed t-test. * = p<0.05.</p

Defatting of fat loaded primary human hepatocytes (PHH).

<p>Panel A: The positive are of oil red O of the defatting treatment group was reduced by 28% in comparison with the vehicle control group over 24 hours and 54% over 48 hours. Panel B: Intracellular triglyceride levels of the defatting treatment group were reduced by 32% within 24 hours of treatment and 35% within 48 hours, in comparison with the fatty vehicle control group. Panel C: Oil red O staining picture of PHH of the defatting group at the end of the 48 hours of treatment. There is a predominance of small lipid droplets in the cytoplasm of the cells and the nucleus is in its usual position. Series 2: shows a series of oil red O staining pictures from PHH in culture at different time points of the experiments. Panel D shows lean cells in culture, after the incubation with fatty acids they become loaded with fat (panel E). Those fat loaded PHH were then incubated with only the vehicle of the drugs for 48 hours and the lipid content decreased over time (panel F) or had the defatting treatment that showed the significant higher decrease in the area of oil red O (panel G). Data report the median of three separate experiments performed in quadruplicate and errors bars the interquartile range. Comparisons performed using two-tailed t-test. * = p<0.05.</p

Study design.

<p>Series 1: Isolated primary human hepatocytes (PHH) were left in standard media for 2 days and then received media supplemented with fatty acids. After 2 days of fat loading the fatty PHH were allocated to the defatting treatment group where the media was supplemented with the defatting cocktail of drugs, and the control groups, the standard control group and the vehicle control group that received vehicle only. Lean hepatocytes were kept in standard culture conditions throughout the experimental period. The experimentation period lasted for two days thereafter. Series 2: Human intra-hepatic endothelial cells (HIEC) and cholangiocytes were immuno-magnetically separated with Dynabeads conjugated with cell-specific monoclonal antibody. The cells were left in culture for 2 days in standard media to reach confluence and then were allocated to the intervention group that received the defatting cocktail and the control groups, the standard control group and the vehicle control group that had the media supplemented with the vehicle only. The experimentation period lasts for two days thereafter.</p

Results of fat loading of primary human hepatocytes.

<p>Panel A: The supplementation of the media with the combination of fatty acids resulted in a cell viability rate of 81% after 48 hours of incubation. Panel B: Oil red O staining image of PHH at the end of the fat loading period. There is predominance of large lipid droplets displacing the nucleus of the cells to the periphery (black arrow). Panel C: At the end of 48 hours of fatting load there was a significant increase of 14-fold of the positive area of oil red O. Panel D: Intracellular triglycerides increased 8-fold within 48 hours of incubation with fatty acids. Data report the median of three separate experiments performed in quadruplicate and errors bars the interquartile range. Comparisons performed using two-tailed t-test. * = p<0.05.</p

Release of total ketones in the supernatants.

<p>Fat loaded primary human hepatocytes that had the defatting treatment showed an increase in cell culture supernatant levels of total ketone bodies of 1.22-fold over 24 hours and 1.40-fold over 48 hours. Data reports the median of three separate experiments performed in quadruplicate and errors bars the interquartile range. Comparisons performed using two-tailed t-test. * = p<0.05.</p