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Background: Liver disease is the third leading cause of premature death in the UK. Transplantation is the only successful treatment for end-stage liver disease but is limited by a shortage of suitable donor organs. As a result, up to 20% of patients on liver transplant waiting lists die before receiving a transplant. A third of donated livers are not suitable for transplant, often due to steatosis. Hepatic steatosis, which affects 33% of the UK population, is strongly associated with obesity, an increasing problem in the potential donor pool. We have recently tested defatting interventions during normothermic machine perfusion (NMP) in discarded steatotic human livers that were not transplanted. A combination of therapies including forskolin (NKH477) and L-carnitine to defat liver cells and lipoprotein apheresis filtration were investigated. These interventions resulted in functional improvement during perfusion and reduced the intrahepatocellular triglyceride (IHTG) content. We hypothesise that defatting during NMP will allow more steatotic livers to be transplanted with improved outcomes., Methods: In the proposed multi-centre clinical trial, we will randomly assign 60 livers from donors with a high-risk of hepatic steatosis to either NMP alone or NMP with defatting interventions. We aim to test the safety and feasibility of the defatting intervention and will explore efficacy by comparing ex-situ and post-reperfusion liver function between the groups. The primary endpoint will be the proportion of livers that achieve predefined functional criteria during perfusion which indicate potential suitability for transplantation. These criteria reflect hepatic metabolism and injury and include lactate clearance, perfusate pH, glucose metabolism, bile composition, vascular flows and transaminase levels. Clinical secondary endpoints will include proportion of livers transplanted in the two arms, graft function; cell-free DNA (cfDNA) at follow-up visits; patient and graft survival; hospital and ITU stay; evidence of ischemia-reperfusion injury (IRI); non-anastomotic biliary strictures and recurrence of steatosis (determined on MRI at 6 months)., Discussion: This study explores ex-situ pharmacological optimisation of steatotic donor livers during NMP. If the intervention proves effective, it will allow the safe transplantation of livers that are currently very likely to be discarded, thereby reducing waiting list deaths., Trial Registration: ISRCTN ISRCTN14957538. Registered in October 2022., (© 2024. The Author(s).)

Dynamic organ preservation is a relatively old technique which has regained significant interest in the last decade. Machine perfusion (MP) techniques are applied in various fields of solid organ transplantation today. The first clinical series of ex situ MP in liver transplantation was presented in 2010. Since then, the number of research and clinical applications has substantially increased. Despite the notable beneficial effect on organ quality and recipient outcome, MP is still not routinely used in liver transplantation. Based on the enormous need to better preserve organs and the subsequent demand to continuously innovate and develop perfusion equipment further, this technology is also beneficial to test and deliver future therapeutic strategies to livers before implantation. This article summarizes the various challenges observed during the current shift from static to dynamic liver preservation in the clinical setting. The different organ perfusion strategies are discussed first, together with ongoing clinical trials and future study design. The current status of research and the impact of costs and regulations is highlighted next. Factors contributing to costs and other required resources for a worldwide successful implementation and reimbursement are presented third. The impact of research on cost-utility and effectivity to guide the tailored decision-making regarding the optimal perfusion strategy is discussed next. Finally, this article provides potential solutions to the challenging field of innovation in healthcare considering the various social and economic factors and the role of clinical, regulatory, and financial stakeholders worldwide., Competing Interests: J.V.G. consults for and received grants from Organ Recovery Systems (Itasca, IL) and consults for GATT Technologies. The other authors declare no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

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 >7.65 and bicarbonate levels >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)., (Copyright © 2023 American Association for the Study of Liver Diseases.)

Extended duration of normothermic machine perfusion (NMP) provides opportunities to resuscitate suboptimal donor livers. This intervention requires adequate oxygen delivery typically provided by a blood-based perfusion solution. Methaemoglobin (MetHb) results from the oxidation of iron within haemoglobin and represents a serious problem in perfusions lasting > 24 h. We explored the effects of anti-oxidant, N-acetylcysteine (NAC) on the accumulation of methaemoglobin. NMP was performed on nine human donor livers declined for transplantation: three were perfused without NAC (no-NAC group), and six organs perfused with an initial NAC bolus, followed by continuous infusion (NAC group), with hourly methaemoglobin perfusate measurements. In-vitro experiments examined the impact of NAC (3 mg) on red cells (30 ml) in the absence of liver tissue. The no-NAC group sustained perfusions for an average of 96 (range 87-102) h, universally developing methaemoglobinaemia (≥ 2%) observed after an average of 45 h, with subsequent steep rise. The NAC group was perfused for an average of 148 (range 90-184) h. Only 2 livers developed methaemoglobinaemia (peak MetHb of 6%), with an average onset of 116.5 h. Addition of NAC efficiently limits formation and accumulation of methaemoglobin during NMP, and allows the significant extension of perfusion duration., (© 2023. The Author(s).)

With the increasing number of accepted candidates on waiting lists worldwide, there is an urgent need to expand the number and the quality of donor livers. Dynamic preservation approaches have demonstrated various benefits, including improving liver function and graft survival, and reducing liver injury and post-transplant complications. Consequently, organ perfusion techniques are being used in clinical practice in many countries. Despite this success, a proportion of livers do not meet current viability tests required for transplantation, even with the use of modern perfusion techniques. Therefore, devices are needed to further optimise machine liver perfusion - one promising option is to prolong machine liver perfusion for several days, with ex situ treatment of perfused livers. For example, stem cells, senolytics, or molecules targeting mitochondria or downstream signalling can be administered during long-term liver perfusion to modulate repair mechanisms and regeneration. Besides, today's perfusion equipment is also designed to enable the use of various liver bioengineering techniques, to develop scaffolds or for their re-cellularisation. Cells or entire livers can also undergo gene modulation to modify animal livers for xenotransplantation, to directly treat injured organs or to repopulate such scaffolds with "repaired" autologous cells. This review first discusses current strategies to improve the quality of donor livers, and secondly reports on bioengineering techniques to design optimised organs during machine perfusion. Current practice, as well as the benefits and challenges associated with these different perfusion strategies are discussed., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

The widespread uptake of different machine perfusion (MP) strategies for liver transplant has been driven by an effort to minimize graft injury. Damage to the cholangiocytes during the liver donation, preservation, or early posttransplant period may result in stricturing of the biliary tree and inadequate biliary drainage. This problem continues to trouble clinicians, and may have catastrophic consequences for the graft and patient. Ischemic injury, as a result of compromised hepatic artery flow, is a well-known cause of biliary strictures, sepsis, and graft failure. However, very similar lesions can appear with a patent hepatic artery and these are known as ischemic type biliary lesions (ITBL) that are attributed to microcirculatory dysfunction rather than main hepatic arterial compromise. Both the warm and cold ischemic period duration appear to influence the onset of ITBL. All of the commonly used MP techniques deliver oxygen to the graft cells, and therefore may minimize the cholangiocyte injury and subsequently reduce the incidence of ITBL. As clinical experience and published evidence grows for these modalities, the impact they have on ITBL rates is important to consider. In this review, the evidence for the three commonly used MP strategies (abdominal normothermic regional perfusion [A-NRP], hypothermic oxygenated perfusion [HOPE], and normothermic machine perfusion [NMP] for ITBL prevention has been critically reviewed. Inconsistencies with ITBL definitions used in trials, coupled with variations in techniques of MP, make interpretation challenging. Overall, the evidence suggests that both HOPE and A-NRP prevent ITBL in donated after circulatory death grafts compared to cold storage. The evidence for ITBL prevention in donor after brain death grafts with any MP technique is weak., Competing Interests: Conflict-of-interest statement: The funding provided for normothermic machine perfusion consumables generously donated by the Ann Fox Foundation, under the umbrella of University Hospital Birmingham Charities., (©The Author(s) 2023. Published by Baishideng Publishing Group Inc. All rights reserved.)

In situ normothermic regional perfusion (NRP) and ex situ normothermic machine perfusion (NMP) aim to improve the outcomes of liver transplantation (LT) using controlled donation after circulatory death (cDCD). NRP and NMP have not yet been compared directly. In this international observational study, outcomes of LT performed between 2015 and 2019 for organs procured from cDCD donors subjected to NRP or NMP commenced at the donor center were compared using propensity score matching (PSM). Of the 224 cDCD donations in the NRP cohort that proceeded to asystole, 193 livers were procured, resulting in 157 transplants. In the NMP cohort, perfusion was commenced in all 40 cases and resulted in 34 transplants (use rates: 70% vs. 85% [p = 0.052], respectively). After PSM, 34 NMP liver recipients were matched with 68 NRP liver recipients. The two cohorts were similar for donor functional warm ischemia time (21 min after NRP vs. 20 min after NMP; p = 0.17), UK-Donation After Circulatory Death risk score (5 vs. 5 points; p = 0.38), and laboratory Model for End-Stage Liver Disease scores (12 vs. 12 points; p = 0.83). The incidence of nonanastomotic biliary strictures (1.5% vs. 2.9%; p > 0.99), early allograft dysfunction (20.6% vs. 8.8%; p = 0.13), and 30-day graft loss (4.4% vs. 8.8%; p = 0.40) were similar, although peak posttransplant aspartate aminotransferase levels were higher in the NRP cohort (872 vs. 344 IU/L; p < 0.001). NRP livers were more frequently allocated to recipients suffering from hepatocellular carcinoma (HCC; 60.3% vs. 20.6%; p < 0.001). HCC-censored 2-year graft and patient survival rates were 91.5% versus 88.2% (p = 0.52) and 97.9% versus 94.1% (p = 0.25) after NRP and NMP, respectively. Both perfusion techniques achieved similar outcomes and appeared to match benchmarks expected for donation after brain death livers. This study may inform the design of a definitive trial., (© 2022 The Authors. Liver Transplantation published by Wiley Periodicals LLC on behalf of American Association for the Study of Liver Diseases.)

Normothermic machine perfusion (NMP) allows objective assessment of donor liver transplantability. Several viability evaluation protocols have been established, consisting of parameters such as perfusate lactate clearance, pH, transaminase levels, and the production and composition of bile. The aims of this study were to assess 3 such protocols, namely, those introduced by the teams from Birmingham (BP), Cambridge (CP), and Groningen (GP), using a cohort of high-risk marginal livers that had initially been deemed unsuitable for transplantation and to introduce the concept of the viability assessment sensitivity and specificity. To demonstrate and quantify the diagnostic accuracy of these protocols, we used a composite outcome of organ use and 24-month graft survival as a surrogate endpoint. The effects of assessment modifications, including the removal of the most stringent components of the protocols, were also assessed. Of the 31 organs, 22 were transplanted after a period of NMP, of which 18 achieved the outcome of 24-month graft survival. The BP yielded 94% sensitivity and 50% specificity when predicting this outcome. The GP and CP both seemed overly conservative, with 1 and 0 organs, respectively, meeting these protocols. Modification of the GP and CP to exclude their most stringent components increased this to 11 and 8 organs, respectively, and resulted in moderate sensitivity (56% and 44%) but high specificity (92% and 100%, respectively) with respect to the composite outcome. This study shows that the normothermic assessment protocols can be useful in identifying potentially viable organs but that the balance of risk of underuse and overuse varies by protocol., (© 2021 The Authors. Liver Transplantation published by Wiley Periodicals LLC on behalf of American Association for the Study of Liver Diseases.)

Competing Interests: Conflict of interests disclosure DFM holds shares in the OrganOx Limited company. None of the other authors have any conflict of interest to disclose.

The increasing disparity between the number of patients listed for transplantation and the number of suitable organs has led to the increasing use of extended criteria donors (ECDs). ECDs are at increased risk of developing ischaemia reperfusion injury and greater risk of post-transplant complications. Ischaemia reperfusion injury is a major complication of organ transplantation defined as the inflammatory changes seen following the disruption and restoration of blood flow to an organ-it is a multifactorial process with the potential to cause both local and systemic organ failure. The utilisation of machine perfusion under normothermic (37 degrees Celsius) and hypothermic (4-10 degrees Celsius) has proven to be a significant advancement in organ preservation and restoration. One of the key benefits is its ability to optimise suboptimal organs for successful transplantation. This review is focused on examining ischaemia reperfusion injury and how machine perfusion ameliorates the graft's response to this.

Purpose of Review: To summarize key studies in liver preservation published over the last 3 years and evaluate benefits and limitations of the different perfusion techniques. Selected experimental applications that may be translated to the clinical use will be also discussed., Recent Findings: Normothermic machine perfusion (NMP) has transitioned into clinical practice. Viability assessment is a reliable tool for clinical decision-making, and safety of the back-to-base approach has facilitated adoption of the technology. Data supporting well tolerated use of declined livers after NMP and new protocols selecting complex recipients aim to improve access to suitable organs. Hypothermic machine perfusion (HMP) is showing promising clinical results by decreasing biliary complications in recipients' receiving organs donated after circulatory death (DCD) and improving early graft function in extended criteria organs. Long-term data of HMP on DCD livers shows improved graft survival over standard SCS. Novel approaches utilizing sequential HMP--NMP or ischaemia-free preservation aim to improve outcomes of extended criteria organs., Summary: Machine perfusion for organ transplantation has become an established technique but the field is rapidly evolving. Ongoing research focuses on evaluation of the intervention efficacy and finding optimal indications to use each perfusion strategy according to graft type and clinical scenario., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Ex situ donor liver machine perfusion is a promising tool to assess organ viability prior to transplantation and platform to investigate novel therapeutic interventions. However, the wide variability in donor and graft characteristics between individual donor livers limits the comparability of results. We investigated the hypothesis that the development of a split liver ex situ machine perfusion protocol provides the ideal comparative controls in the investigation of machine perfusion techniques and therapeutic interventions, thus leading to more comparable results. Methods: Four discarded human donor livers were surgically split following identification and separation of right and left inflow and outflow vessels. Each lobe, on separate perfusion machines, was subjected to normothermic perfusion using an artificial hemoglobin-based oxygen carrier solution for 6 h. Metabolic parameters as well as hepatic artery and portal vein perfusion parameters monitored. Results: Trends in hepatic artery and portal vein flows showed a general increase in both lobes throughout each perfusion experiment, even when normalized for tissue weight. Progressive decreases in perfusate lactate and glucose levels exhibited comparable trends in between lobes. Conclusion: Our results demonstrate comparability between right and left lobes when simultaneously subjected to normothermic machine perfusion. In the pre-clinical setting, this model provides the ideal comparative controls in the investigation of therapeutic interventions., Competing Interests: JA is a clinical research fellow at the Queen Elizabeth Hospital in Birmingham and employed by University Hospitals Birmingham. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Attard, Osei-Bordom, Boteon, Wallace, Ronca, Reynolds, Perera, Oo, Mergental, Mirza and Afford.)

Background: Hepatic artery stenosis (HAS) following liver transplantation results in hypoperfusion and ischemic damage to the biliary tree. This study aimed to investigate how vascular intervention, liver function test derangement, and time point of HAS onset influence biliary complications., Methods: A single-center retrospective study of adult patients that underwent primary liver transplantation. Patients were grouped according to the presence or absence of HAS and then into early (≤90 d) or late (>90 d) subgroups. Biliary complications comprised anastomotic (AS) or non ASs (NASs)., Results: Computed tomography angiography confirmed HAS was present in 39 of 1232 patients (3.2%). This occurred at ≤90 and >90 days in 20 (1.6%) and 19 (1.5%), respectively. The incidence of biliary strictures (BSs) in the group with HAS was higher than the group without (13/39; 33% versus 85/1193; 7.1%, P = 0.01). BS occurred in 8/20 (40.0%) and 5/19 (26.3%) of the early and late groups, respectively. The need for biliary intervention increased if any liver function test result was ≥3× upper limit of normal ( P = 0.019)., Conclusions: BS occurs at a significantly higher rate in the presence of HAS. Onset of HAS at ≤90 or ≥90 days can both be associated with morbidity. Significant liver function test derangement at HAS diagnosis indicates a higher likelihood of biliary intervention for strictures., Competing Interests: The authors declare no funding or conflicts of interest., (Copyright © 2020 The Author(s). Transplantation Direct. Published by Wolters Kluwer Health, Inc.)

Background: Aberrant hepatic arterial anatomy may be seen in up to 30% of liver grafts, and reconstruction prolongs the cold ischemic time or the arterialization times. If normothermic machine preservation (NMP) is used to preserve liver grafts, the presence of aberrant arterial anatomy poses a challenge. Dual arterial cannulation is a temporary solution to enable effective perfusion, until optimal circumstances are met for arterial reconstruction, without compromising ischemia time. To date the technical and logistical feasibility of arterial reconstruction ex situ and during NMP has not been reported., Methods: Series of 5 cases from the Consortium for Organ Preservation in Europe randomized controlled trial in which grafts with arterial anatomic variations were reconstructed while organs were perfused on NMP., Results: One donor after cardiac death and 4 donor after brain death livers with arterial anatomical variations reconstructed while on NMP were included. All patients survived transplantation, spending 1-7 d in intensive care unit and discharged home after 5-15 d. None of the cases developed early allograft dysfunction or any early technical complications. At follow-up, there were no late hepatic artery thrombosis, stenosis, or any other vascular-related complication. Four of 5 patients underwent magnetic resonance cholangiopancreatography at 6 mo with no evidence of ischemic cholangiopathy., Conclusions: The case series described above suggests that ex vivo arterial reconstruction surgery on liver grafts while on board the NMP device is feasible, safe, and effective., Competing Interests: P.F. is cofounder, Chief Medical Officer, and consultant to OrganOX Limited and also holds shares in the company. D.M. holds minor shares in OrganOX Limited. The other authors declare no conflicts of interest., (Copyright © 2020 The Author(s). Transplantation Direct. Published by Wolters Kluwer Health, Inc.)

Background: Pre-clinical research with multi-potent adult progenitor cells (MAPC® cells, Multistem, Athersys Inc., Cleveland, Ohio) suggests their potential as an anti-inflammatory and immunomodulatory therapy in organ transplantation. Normothermic machine perfusion of the liver (NMP-L) has been proposed as a way of introducing therapeutic agents into the donor organ. Delivery of cellular therapy to human donor livers using this technique has not yet been described in the literature. The primary objectives of this study were to develop a technique for delivering cellular therapy to human donor livers using NMP-L and demonstrate engraftment. Methods: Six discarded human livers were perfused for 6 h at 37°C using the Liver Assist (Organ Assist, Groningen). 50 × 106 CMPTX-labeled MAPC cells were infused directly into the right lobe via the hepatic artery (HA, n = 3) or portal vein (PV, n = 3) over 20 min at different time points during the perfusion. Perfusion parameters were recorded and central and peripheral biopsies were taken at multiple time-points from both lobes and subjected to standard histological stains and confocal microscopy. Perfusate was analyzed using a 35-plex multiplex assay and proteomic analysis. Results: There was no detrimental effect on perfusion flow parameters on infusion of MAPC cells by either route. Three out of six livers met established criteria for organ viability. Confocal microscopy demonstrated engraftment of MAPC cells across vascular endothelium when perfused via the artery. 35-plex multiplex analysis of perfusate yielded 13 positive targets, 9 of which appeared to be related to the infusion of MAPC cells (including Interleukin's 1b, 4, 5, 6, 8, 10, MCP-1, GM-CSF, SDF-1a). Proteomic analysis revealed 295 unique proteins in the perfusate from time-points following the infusion of cellular therapy, many of which have strong links to MAPC cells and mesenchymal stem cells in the literature. Functional enrichment analysis demonstrated their immunomodulatory potential. Conclusion: We have demonstrated that cells can be delivered directly to the target organ, prior to host immune cell population exposure and without compromising the perfusion. Transendothelial migration occurs following arterial infusion. MAPC cells appear to secrete a host of soluble factors that would have anti-inflammatory and immunomodulatory benefits in a human model of liver transplantation., (Copyright © 2020 Laing, Stubblefield, Wallace, Roobrouck, Bhogal, Schlegel, Boteon, Reynolds, Ting, Mirza, Newsome, Mergental and Afford.)

There is a limited access to liver transplantation, however, many organs are discarded based on subjective assessment only. Here we report the VITTAL clinical trial (ClinicalTrials.gov number NCT02740608) outcomes, using normothermic machine perfusion (NMP) to objectively assess livers discarded by all UK centres meeting specific high-risk criteria. Thirty-one livers were enroled and assessed by viability criteria based on the lactate clearance to levels ≤2.5 mmol/L within 4 h. The viability was achieved by 22 (71%) organs, that were transplanted after a median preservation time of 18 h, with 100% 90-day survival. During the median follow up of 542 days, 4 (18%) patients developed biliary strictures requiring re-transplantation. This trial demonstrates that viability testing with NMP is feasible and in this study enabled successful transplantation of 71% of discarded livers, with 100% 90-day patient and graft survival; it does not seem to prevent non-anastomotic biliary strictures in livers donated after circulatory death with prolonged warm ischaemia.

Liver ischaemia-reperfusion injury (IRI) is an intrinsic part of the transplantation process and damages the parenchymal cells of the liver including hepatocytes, endothelial cells and cholangiocytes. Many biomarkers of IRI have been described over the past two decades that have attempted to quantify the extent of IRI involving different hepatic cellular compartments, with the aim to allow clinicians to predict the suitability of donor livers for transplantation. The advent of machine perfusion has added an additional layer of complexity to this field and has forced researchers to re-evaluate the utility of IRI biomarkers in different machine preservation techniques. In this review, we summarise the current understanding of liver IRI biomarkers and discuss them in the context of machine perfusion.

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 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., Methods: Ten 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., Results: The 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., Conclusion: The 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., Competing Interests: The machine perfusion research was funded by the Queen Elizabeth Hospital Birmingham Charity’s Liver Foundation UK. YLB is funded by the NIHR Wellcome Trust. Hemopure® was provided free of charge by Hemoglobin Oxygen Therapeutics LLC. The company has not had any role in the study design, data collection, analysis, interpretation or manuscript preparation. The authors are employees of the University Hospital Birmingham or the University of Birmingham and none of them received any payment or have any conflict of interest related to this manuscript. This does not alter the authors’ adherence to PLOS ONE policies on sharing data and materials.

Liver transplantation is an effective intervention for end-stage liver disease, fulminant hepatic failure, and early hepatocellular carcinoma. Yet, there is marked patient-to-patient variation in liver transplantation outcomes. This calls for novel diagnostics to enable rational deployment of donor livers. Metabolomics is a postgenomic high-throughput systems biology approach to diagnostic innovation in clinical medicine. We report here an original systematic review of the metabolomic studies that have identified putative biomarkers in the context of liver transplantation. Eighteen studies met the inclusion criteria that involved sampling of blood ( n  = 4), dialysate fluid ( n  = 4), bile ( n  = 5), and liver tissue ( n  = 5). Metabolites of amino acid and nitrogen metabolism, anaerobic glycolysis, lipid breakdown products, and bile acid metabolism were significantly different in transplanted livers with and without graft dysfunction. However, criteria for defining the graft dysfunction varied across studies. This systematic review demonstrates that metabolomics can be deployed in identification of metabolic indicators of graft dysfunction with a view to implicated molecular mechanisms. We conclude the article with a horizon scanning of metabolomics technology in liver transplantation and its future prospects and challenges in research and clinical practice.

Clinical adoption of normothermic machine perfusion (NMP) may be facilitated by simplifying logistics and reducing costs. This can be achieved by cold storage of livers for transportation to recipient centers before commencing NMP. The purpose of this study was to assess the safety and feasibility of post-static cold storage normothermic machine perfusion (pSCS-NMP) in liver transplantation. In this multicenter prospective study, 31 livers were transplanted. The primary endpoint was 30-day graft survival. Secondary endpoints included the following: peak posttransplant aspartate aminotransferase (AST), early allograft dysfunction (EAD), postreperfusion syndrome (PRS), adverse events, critical care and hospital stay, biliary complications, and 12-month graft survival. The 30-day graft survival rate was 94%. Livers were preserved for a total of 14 hours 10 minutes ± 4 hours 46 minutes, which included 6 hours 1 minute ± 1 hour 19 minutes of static cold storage before 8 hours 24 minutes ± 4 hours 4 minutes of NMP. Median peak serum AST in the first 7 days postoperatively was 457 U/L (92-8669 U/L), and 4 (13%) patients developed EAD. PRS was observed in 3 (10%) livers. The median duration of initial critical care stay was 3 days (1-20 days), and median hospital stay was 13 days (7-31 days). There were 7 (23%) patients who developed complications of grade 3b severity or above, and 2 (6%) patients developed biliary complications: 1 bile leak and 1 anastomotic stricture with no cases of ischemic cholangiopathy. The 12-month overall graft survival rate (including death with a functioning graft) was 84%. In conclusion, this study demonstrates that pSCS-NMP was feasible and safe, which may facilitate clinical adoption., (Copyright © 2019 by the American Association for the Study of Liver Diseases.)

Background: Normothermic machine perfusion (NMP) of liver grafts is increasingly being incorporated in clinical practice. Current evidence has shown NMP plays a role in reconditioning the synthetic and energy capabilities of grafts. Intraoperative coagulation profile is a surrogate of graft quality and preservation status; however, to date this aspect has not been documented., Methods: The liver transplantation recipients who received NMP liver grafts in the QEHB between 2013 and 2016 were compared in terms of intraoperative thromboelastography characteristics (R time, K time, α-angle, maximum amplitude, G value, and LY30) to a propensity score-matched control group, where the grafts were preserved by traditional static cold storage (SCS)., Results: After propensity matching, none of the thromboelastography characteristics were found to differ significantly between the 72 pairs of SCS and NMP organs when measured preimplantation. However, postimplantation, NMP organs had significantly shorter K time (median: 2.8 vs 3.6 min, P = 0.010) and R + K time (11.4 vs 13.7 min, P = 0.016), as well as significantly larger α-angle (55.9° vs 44.8°, P = 0.002), maximum amplitude (53.5 vs 49.6 mm, P = 0.044), and G values (5.8 vs 4.9k dynes/cm, P = 0.043) than SCS organs. Hyperfibrinolysis after implantation was also mitigated by NMP, with fewer patients requiring aggressive factor correction during surgery (LY30 = 0, NMP vs SCS: 83% vs 60%, P = 0.004). Consequently, NMP organs required significantly fewer platelet units to be transfused during the transplant procedure (median: 0 vs 5, P = 0.001)., Conclusions: In this study, we have shown that NMP liver grafts return better coagulation profiles intraoperatively, which could be attributed to the preservation of liver grafts under physiological conditions.

Strategies to increase the use of steatotic donor livers 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. Because of steatosis, 10 livers were discarded and were allocated either to a defatting group that had the perfusate supplemented with a combination of drugs to enhance lipid metabolism or to a control group that received perfusion fluid with vehicle only. Steatosis was assessed using tissue homogenate and histological analyses. Markers for lipid oxidation and solubilization, oxidative injury, inflammation, and biliary function were evaluated by enzyme-linked immunosorbent assay, immunohistochemistry, and in-gel protein detection. Treatment reduced tissue triglycerides by 38% and macrovesicular steatosis by 40% over 6 hours. This effect was driven by increased solubility of the triglycerides (P = 0.04), and mitochondrial oxidation as assessed by increased ketogenesis (P = 0.008) and adenosine triphosphate synthesis (P = 0.01) were associated with increased levels of the enzymes acyl-coenzyme A oxidase 1, carnitine palmitoyltransferase 1A, and acetyl-coenzyme A 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 down-regulated the expression of markers for oxidative injury as well as activation of immune cells (CD14; CD11b) and reduced the release of inflammatory cytokines in the perfusate (tumor necrosis factor α; interleukin 1β). In 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., (Copyright © 2019 The Authors. Liver Transplantation published by Wiley Periodicals, Inc., on behalf of the American Association for the Study of Liver Diseases.)

Parameters of retrieval surgery are meticulously documented in the United Kingdom, where up to 40% of livers are donation after circulatory death (DCD) donations. This retrospective analysis focuses on outcomes after transplantation of DCD livers, retrieved by different UK centers between 2011 and 2016. Donor and recipient risk factors and the donor retrieval technique were assessed. A total of 236 DCD livers from 9 retrieval centers with a median UK DCD risk score of 5 (low risk) to 7 points (high risk) were compared. The majority used University of Wisconsin solution for aortic flush with a median hepatectomy time of 27-44 minutes. The overall liver injury rate appeared relatively high (27.1%) with an observed tendency toward more retrieval injuries from centers performing a quicker hepatectomy. Among all included risk factors, the UK DCD risk score remained the best predictor for overall graft loss in the multivariate analysis (P < 0.001). In high-risk and futile donor-recipient combinations, the occurrence of liver retrieval injuries had negative impact on graft survival (P = 0.023). Expectedly, more ischemic cholangiopathies (P = 0.003) were found in livers transplanted with a higher cumulative donor-recipient risk. Although more biliary complications with subsequent graft loss were found in high-risk donor-recipient combinations, the impact of the standardized national retrieval practice on outcomes after DCD liver transplantation was minimal., (Copyright © 2018 by the American Association for the Study of Liver Diseases.)

Background: Strategies for successful transplantation are much needed in the era of organ shortage, and there has been a resurgence of interest on the impact of revascularization time (RT) on outcomes in liver transplantation (LT)., Methods: All primary LT performed in Birmingham between 2009 and 2014 (n = 678) with portal reperfusion first were stratified according to RT (<44 minutes vs ≥44 minutes) and graft quality (standard liver graft [SLG], Donor Risk Index < 2.3 vs marginal liver graft [MLG], Donor Risk Index ≥ 2.3)., Results: Revascularization time of 44 minutes or longer resulted in significantly greater incidence of early allograft dysfunction (EAD) (29% vs 47%, P < 0.001), posttransplant acute kidney injury (AKI) (39% vs 60%, P < 0.001), and new-onset AKI (37% vs 56%, P < 0.001), along with poor long-term outcome (3-year graft survival 92% vs 83%, P = 0.001; 3-year patient survival 87% vs 79%, P = 0.004). On multivariable analysis, RT ≥ 44 was a significant independent predictor of EAD, renal dysfunction, and overall graft survival, but not patient survival. The cumulative effect of prolonged revascularization in marginal grafts (MLG) resulted in the worst transplant outcome compared with all other groups, which could be mitigated by rapid revascularization (SLG, SLG, MLG vs MLG; EAD 24%, 39%, 39% vs 69%; AKI 32%, 46%, 51% vs 70%; 3-year graft survival 94%, 87%, 88% vs 70%, respectively; each P < 0.001). Factors associated with lack of abdominal space, larger grafts, and surgical skills were predictive of RT ≥ 44., Conclusions: Shorter graft revascularization is a protective factor in LT, particularly in the setting of graft marginality. Careful graft-recipient matching and emphasis on surgical expertise may aid in achieving better outcomes in LT.

Hypothermic oxygenated perfusion (HOPE) and normothermic perfusion are seen as distinct techniques of ex situ machine perfusion of the liver. We aimed to demonstrate the feasibility of combining both techniques and whether it would improve functional parameters of donor livers into transplant standards. Ten discarded human donor livers had either 6 hours of normothermic perfusion (n = 5) or 2 hours of HOPE followed by 4 hours of normothermic perfusion (n = 5). Liver function was assessed according to our viability criteria; markers of tissue injury and hepatic metabolic activity were compared between groups. Donor characteristics were comparable. During the hypothermic perfusion phase, livers down-regulated mitochondrial respiration (oxygen uptake, P = 0.04; partial pressure of carbon dioxide perfusate, P = 0.04) and increased adenosine triphosphate levels 1.8-fold. Following normothermic perfusion, those organs achieved lower tissue expression of markers of oxidative injury (4-hydroxynonenal, P = 0.008; CD14 expression, P = 0.008) and inflammation (CD11b, P = 0.02; vascular cell adhesion molecule 1, P = 0.05) compared with livers that had normothermic perfusion alone. All livers in the combined group achieved viability criteria, whereas 40% (2/5) in the normothermic group failed (P = 0.22). In conclusion, this study suggests that a combined protocol of hypothermic oxygenated and normothermic perfusions might attenuate oxidative stress, tissue inflammation, and improve metabolic recovery of the highest-risk donor livers compared with normothermic perfusion alone., (Copyright © 2018 The Authors. Liver Transplantation published by Wiley Periodicals, Inc. on behalf of American Association for the Study of Liver Diseases.)

Ischemia/reperfusion injury (IRI) is the main cause of complications following liver transplantation. Reactive oxygen species (ROS) were thought to be the main regulators of IRI. However, recent studies demonstrate that ROS activate the cytoprotective mechanism of autophagy promoting cell survival. Liver IRI initially damages the liver endothelial cells (LEC), but whether ROS-autophagy promotes cell survival in LEC during IRI is not known. Primary human LEC were isolated from human liver tissue and exposed to an in vitro model of IRI to assess the role of autophagy in LEC. The role of autophagy during liver IRI in vivo was assessed using a murine model of partial liver IRI. During IRI, ROS specifically activate autophagy-related protein (ATG) 7 promoting autophagic flux and the formation of LC3B-positive puncta around mitochondria in primary human LEC. Inhibition of ROS reduces autophagic flux in LEC during IRI inducing necrosis. In addition, small interfering RNA knockdown of ATG7 sensitized LEC to necrosis during IRI. In vivo murine livers in uninjured liver lobes demonstrate autophagy within LEC that is reduced following IRI with concomitant reduction in autophagic flux and increased cell death. In conclusion, these findings demonstrate that during liver IRI ROS-dependent autophagy promotes the survival of LEC, and therapeutic targeting of this signaling pathway may reduce liver IRI following transplantation., (© 2018 by the American Association for the Study of Liver Diseases.)

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 >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., (© 2018 by the American Association for the Study of Liver Diseases.)

Long-standing research has shown that increased lipid content in donor livers is associated with inferior graft outcomes posttransplant. The global epidemic that is obesity has increased the prevalence of steatosis in organ donors, to the extent that it has become one of the main reasons for declining livers for transplantation. Consequently, it is one of the major culprits behind the discrepancy between the number of donor livers offered for transplantation and those that go on to be transplanted. Steatotic livers are characterized by poor microcirculation, depleted energy stores because of an impaired capacity for mitochondrial recovery, and a propensity for an exaggerated inflammatory response following reperfusion injury culminating in poorer graft function postoperatively. Ex situ machine perfusion, currently a novel method in graft preservation, is showing great promise in providing a tool for the recovery and reconditioning of marginal livers. Hence, reconditioning these steatotic livers using machine perfusion has the potential to increase the number of liver transplants performed. In this review, we consider the problematic issues associated with fatty livers in the realm of transplantation and discuss pharmacological and nonpharmacological options that are being developed to enhance recovery of these organs using machine perfusion and defatting strategies., (© 2018 The American Society of Transplantation and the American Society of Transplant Surgeons.)

Background: Causes of severe cholestasis after liver transplantation (LT) are multi-factorial. Although the etiology is predictable in some, others culminate in graft/patient loss without a definitive cause identified. Severe cholestasis is usually associated with overlapped histological findings of rejection and biliary features, and diagnostic interpretation may pose a challenge., Methods: This is 10-year retrospective analysis of patients with unexplained severe cholestasis resulting in death/graft loss within 90 days of LT. Of 1 583 LT during the study period, 90-day graft failure occurred in 129 (8%) cases; a total of 45 (3%) patients had unresolving severe cholestasis (bilirubin, >100 μmol/L; alkaline phosphatase, >400 UI/L after 15 days from LT), excluding those due to primary nonfunction/sepsis/vascular causes (n = 84). Demographics, allograft biopsies, radiological investigations, and clinical outcome were analyzed., Results: All patients had persistent abnormal liver biochemistry. Doppler ultrasound scan was normal in all cases. Thirty-five (78%) recipients had at least 1 allograft biopsy (2 [1-9]). On the first biopsy, 22 (63%) patients had acute rejection, 4 (18%) early-chronic rejection, 12 (34%) antibody-mediated rejection. In subsequent biopsies chronic rejection was evident in 5 (14%) cases. Donor-specific antibodies were detected in all patients tested. Biliary anatomy was studied in detail in 9 (20%) patients, all presenting biliary strictures. The majority (n = 39; 87%) died within 32 (10-91) days, only survivors were from retransplantation (n = 3;6.5%) and biliary intervention (n = 3;6.5%)., Conclusions: Unresolving severe cholestasis after LT is a key parameter predicting patient/allograft outcome. Histologically, rejection seems to overlap with biliary strictures; hence, allograft biopsy with signs of rejection should not be a reason to overlook biliary problems, in particular when biliary features are present. Only extensive radiological investigation/intervention or retransplantation prevents patient/allograft loss.

While majority of liver transplants worldwide continue to be performed using deceased donor organs, the demands for donor livers continues to exceed the current supply. In an attempt to maximize the number of potentially usable donor livers and expand the current donor pool, there is intense global research by various groups exploring the role of machine perfusion in the liver transplantation, particularly with respect to the machine perfusion of extended-criteria liver donors. In this review, the authors summarize the current field of machine perfusion strategies as applied to deceased donor liver transplantation and how therapeutic targeting of the liver sinusoidal endothelial cell may improve the quality of donor livers., Competing Interests: Disclosure The authors report no conflicts of interest in this work., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Introduction: Pharmacological defatting of rat hepatocytes and hepatoma cell lines suggests that the same method could be used to ameliorate macrovesicular steatosis in moderate to severely fatty livers. However there is no data assessing the effects of those drugs on primary human liver cells. We aimed to determine the effectiveness of a pharmacological cocktail in reducing the in vitro lipid content of primary human hepatocytes (PHH). In addition we sought to determine the cytotoxicity of the cocktail towards non-parenchymal liver cells., Methods: Steatosis was induced in PHH by supplementation with a combination of saturated and unsaturated free fatty acids. This was followed by addition of a defatting drug cocktail for up to 48 hours. The same experimental method was used with human intra-hepatic endothelial cells (HIEC) and human cholangiocytes. MTT assay was used to assess cell viability, triglyceride quantification and oil red O staining were used to determine intracellular lipids content whilst ketone bodies were measured in the supernatants following experimentation., Results: Incubation of fat loaded PHH with the drugs over 48 hours reduced the intracellular lipid area by 54%, from 12.85% to 5.99% (p = 0.002) (percentage of total oil red O area), and intracellular triglyceride by 35%, from 28.24 to 18.30 nmol/million of cells (p<0.001). Total supernatant ketone bodies increased 1.4-fold over 48 hours in the defatted PHH compared with vehicle controls (p = 0.002). Moreover incubation with the drugs for 48 hours increased the viability of PHH by 11%, cholangiocytes by 25% whilst having no cytotoxic effects on HIEC., Conclusion: These data demonstrate that pharmacological intervention can significantly decrease intracellular lipid content of PHH, increase fatty acids β-oxidation whilst being non-toxic to PHH, HIEC or cholangiocytes., Competing Interests: The authors have declared that no competing interests exist.

Liver transplantation is a highly successful treatment, but is severely limited by the shortage in donor organs. However, many potential donor organs cannot be used; this is because sub-optimal livers do not tolerate conventional cold storage and there is no reliable way to assess organ viability preoperatively. Normothermic machine perfusion maintains the liver in a physiological state, avoids cooling and allows recovery and functional testing. Here we show that, in a randomized trial with 220 liver transplantations, compared to conventional static cold storage, normothermic preservation is associated with a 50% lower level of graft injury, measured by hepatocellular enzyme release, despite a 50% lower rate of organ discard and a 54% longer mean preservation time. There was no significant difference in bile duct complications, graft survival or survival of the patient. If translated to clinical practice, these results would have a major impact on liver transplant outcomes and waiting list mortality.

Background: Loco-regional complications of transarterial chemoembolization (TACE) may adversely affect technical aspects of the liver transplantation (LT). This study reviewed the impact of those complications on postoperative outcomes encompassing implications on graft selection., Methods: A retrospective, propensity score matching (1:1) analysis accounting for donor and recipient confounders was performed on a dataset of patients undergoing LT for hepatocellular carcinoma. Outcomes of patients who had TACE (TACE-group) were compared with those who did not (NoTACE-group)., Results: A total of 57 matched pairs were analyzed. TACE achieved effective tumor control (Pre-TACE vs Post-TACE; Median: 44 mm [interquartile range: 43-50] vs 17 mm [0-36]; P = .002) on imaging follow-up. TACE group had, at the hepatectomy, higher incidence of ischemia-related complications (adhesions of the necrotic tumor, cholecystitis, and/or bile duct necrosis) (40.4% vs 10.5%; P = .001). Overall major post-LT complications rate (Dindo-Clavien ≥3) were similar (P = .134). Those in the TACE group with donors after circulatory death (DCD) had 4.6% 90-day mortality and 54.3% major complication rate compared to 6.9% and 77.3% (P = .380 and P = .112, respectively)., Conclusion: TACE was an effective bridging procedure that may complicate LT inducing ischemic-related complications; nevertheless, it has not shown repercussions on mortality or morbidity after the procedure, even using donors after circulatory death., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: In the United Kingdom, up to 20% of liver graft offers are not used for transplantation, and the reasons for graft refusal are multifactorial and not consistent among transplant units., Methods: Liver grafts previously declined by other transplant centers in the United Kingdom but transplanted in our unit in Birmingham between 2011 and 2015 were analyzed. According to the indicated reason for previous declines, liver grafts were categorized into 3 refusal groups: "quality," "logistics," and "other reasons." Results were compared with a matched, low-risk cohort of livers primarily accepted and transplanted at our center., Results: During the study period, 206 livers (donation after brain death: n = 141 (68.4%); donation after circulatory arrest: n = 65 (31.6%) were transplanted, which were previously discarded by a median of 4 other UK centers. The majority of declines were donor quality (n = 102; 49.5%), refusals followed by logistics (n = 45; 21.8%), and other reasons (n = 59; 28.6%). Transplantation from both graft types (donation after brain death and donation after circulatory arrest) and all 3 refusal groups achieved equally good outcomes with an overall low complication rate. The incidence of primary nonfunction (2.4% vs 1.7%; P = 0.5483), in-hospital mortality (6.3% vs 4.1%; P = 0.2293) and 3-year graft (82.5% vs 84.1%; P = 0.6872) and patient (85.4% vs 87.6%; P = 0.8623) survival was comparable between livers previously declined and livers primarily accepted and transplanted at our center., Conclusions: Transplantation of declined livers can achieve comparable outcomes to primary liver low-risk graft offers. Previous refusal should not be taken as a barrier to use the graft, and with appropriate recipient selection, more lives could be saved.

Background & Aims: Primary non-function and ischaemic cholangiopathy are the most feared complications following donation-after-circulatory-death (DCD) liver transplantation. The aim of this study was to design a new score on risk assessment in liver-transplantation DCD based on donor-and-recipient parameters., Methods: Using the UK national DCD database, a risk analysis was performed in adult recipients of DCD liver grafts in the UK between 2000 and 2015 (n = 1,153). A new risk score was calculated (UK DCD Risk Score) on the basis of a regression analysis. This is validated using the United Network for Organ Sharing database (n = 1,617) and our own DCD liver-transplant database (n = 315). Finally, the new score was compared with two other available prediction systems: the DCD risk scores from the University of California, Los Angeles and King's College Hospital, London., Results: The following seven strongest predictors of DCD graft survival were identified: functional donor warm ischaemia, cold ischaemia, recipient model for end-stage liver disease, recipient age, donor age, previous orthotopic liver transplantation, and donor body mass index. A combination of these risk factors (UK DCD risk model) stratified the best recipients in terms of graft survival in the entire UK DCD database, as well as in the United Network for Organ Sharing and in our own DCD population. Importantly, the UK DCD Risk Score significantly predicted graft loss caused by primary non-function or ischaemic cholangiopathy in the futile group (>10 score points). The new prediction model demonstrated a better C statistic of 0.79 compared to the two other available systems (0.71 and 0.64, respectively)., Conclusions: The UK DCD Risk Score is a reliable tool to detect high-risk and futile combinations of donor-and-recipient factors in DCD liver transplantation. It is simple to use and offers a great potential for making better decisions on which DCD graft should be rejected or may benefit from functional assessment and further optimization by machine perfusion., Lay Summary: In this study, we provide a new prediction model for graft loss in donation-after-circulatory-death (DCD) liver transplantation. Based on UK national data, the new UK DCD Risk Score involves the following seven clinically relevant risk factors: donor age, donor body mass index, functional donor warm ischaemia, cold storage, recipient age, recipient laboratory model for end-stage liver disease, and retransplantation. Three risk classes were defined: low risk (0-5 points), high risk (6-10 points), and futile (>10 points). This new model stratified best in terms of graft survival compared to other available models. Futile combinations (>10 points) achieved an only very limited 1- and 5-year graft survival of 37% and less than 20%, respectively. In contrast, an excellent graft survival has been shown in low-risk combinations (≤5 points). The new model is easy to calculate at the time of liver acceptance. It may help to decide which risk combination will benefit from additional graft treatment, or which DCD liver should be declined for a certain recipient., (Copyright © 2017 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.)

Advanced donor age has been identified as a risk factor when combined with donor warm ischemia time (WIT), eg, in donation after circulatory death (DCD). In several countries, DCD livers older than 60 years are not considered suitable due to concerns related to poor graft function and development of ischemic cholangiopathy. In this study, we evaluate outcomes after DCD liver transplantation using grafts from donors older than 60 years. We analyzed outcomes after DCD liver transplantation (n = 315), comparing donors > 60 years (n = 93) and donors ≤ 60 years (n = 222) from our center between 2005 and 2015. End points included graft function and complications and patient and graft survival. Multivariate risk analysis was performed to define further key factors that predicted inferior outcome. Donor age at the cutoff 60 years failed to stratify patient and graft survival. The rate of vascular, biliary, and overall complications was comparably low in both cohorts, and the median comprehensive complication index was 42.7 points, independent from the donor age. Second, donor body mass index (BMI) above a threshold of 25 kg/m 2 significantly impacted on graft and patient survival at any donor age, whereas donor WIT and cold ischemia times were not predictive for graft loss. In conclusion, older DCD donors can be successfully used for liver transplantation with good longterm outcomes when further risk factors are limited. Additional risk is transmitted by an increased donor BMI regardless of donor age. Liver Transplantation 24 352-362 2018 AASLD., (© 2017 by the American Association for the Study of Liver Diseases.)

Purpose of the Review: Machine perfusion (MP) is a novel technology recently introduced in liver transplantation, redefining the current practice of organ preservation and pushing the limits of high-risk liver utilisation. This review highlights the key benefits of machine perfusion over conventional static cold storage (SCS), demonstrated in human liver research and clinical transplants., Recent Findings: The first clinical trials have demonstrated both safety and feasibility of MP. The most recent transplant series and result from a randomised trial suggest the technology is superior to SCS. The key benefits include extended period of organ preservation, decreased incidence of early allograft dysfunction and reduction of biliary complications. Normothermic liver perfusion allows viability testing to guide transplantability of the highest-risk organs. This technology also provides opportunities for therapeutic interventions to improve liver function and quality in organs that are currently declined for clinical use., Summary: Machine perfusion is likely to transform the liver preservation pathway and to improve utilisation of high-risk grafts., Competing Interests: Compliance with Ethical StandardsThe authors declare that they have no conflict of interest.This article does not contain any studies with human or animal subjects performed by any of the authors.

Ischaemia-reperfusion injury (IRI) is the leading cause of injury seen in the liver following transplantation. IRI also causes injury following liver surgery and haemodynamic shock. The first cells within the liver to be injured by IRI are the liver sinusoidal endothelial cells (LSEC). Recent evidence suggests that LSEC co-ordinate and regulates the livers response to a variety of injuries. It is becoming increasingly apparent that the cyto-protective cellular process of autophagy is a key regulator of IRI. In particular LSEC autophagy may be an essential gatekeeper to the development of IRI. The recent availability of liver perfusion devices has allowed for the therapeutic targeting of autophagy to reduce IRI. In particular normothermic machine liver perfusion (NMP-L) allow the delivery of pharmacological agents to donor livers whilst maintaining physiological temperature and hepatic flow rates. In this review we summarise the current understanding of endothelial autophagy and how this may be manipulated during NMP-L to reduce liver IRI., Competing Interests: Conflict-of-interest statement: No potential conflicts of interest relevant to this article were reported.