Assessment of liver graft quality during hypothermic oxygenated perfusion: the first international validation study.

BACKGROUND AND AIM: While it is currently assumed that liver assessment is only possible during normothermic machine perfusion (NMP), there is uncertainty regarding a reliable and quick prediction of graft injury during ex situ hypothermic oxygenated perfusion (HOPE). We therefore intended to test, in an international liver transplant cohort, recently described mitochondrial injury biomarkers measured during HOPE before liver transplantation. STUDY DESIGN: Perfusate samples of human livers from 10 centers in 7 countries with HOPE-experience were analyzed for released mitochondrial compounds, i.e. flavin mononucleotide (FMN), NADH, purine derivates and inflammatory markers. Perfusate FMN was correlated with graft loss due to primary non-function or symptomatic non-anastomotic biliary strictures (NAS), and kidney failure, as well as liver injury after transplantation. Livers deemed unsuitable for transplantation served as negative control. RESULTS: We collected 473 perfusate samples of human DCD (n=315) and DBD livers (n=158). Fluorometric assessment of FMN in perfusate was validated by mass spectrometry (R=0.7011,p<0.0001). Graft loss due to primary non-function or cholangiopathy was predicted by perfusate FMN values (c-statistic mass spectrometry 0.8418 (95%CI 0.7466-0.9370,p<0.0001), c-statistic fluorometry 0.7733 (95%CI 0.7006-0.8461,p<0.0001). Perfusate FMN values were also significantly correlated with symptomatic NAS and kidney failure, and superior in prediction of graft loss when compared to conventional scores derived from donor and recipient parameters, such as the donor risk index and the balance of risk score. Mitochondrial FMN values in liver tissues of non-utilized livers were low, and inversely correlated to high perfusate FMN values and purine metabolite release. CONCLUSIONS: This first international study validates the predictive value of the mitochondrial co-factor FMN, released from complex I during HOPE, and may therefore contribute to a better risk stratification of injured livers before implantation. IMPACT AND IMPLICATIONS: Analysis of 473 perfusates, collected from 10 international centers during hypothermic oxygenated perfusion (HOPE), revealed that mitochondria derived flavin mononucleotide (FMN) values in perfusate is predictive for graft loss, cholangiopathy, and kidney failure after liver transplantation. This result is of high clinical relevance, as recognition of graft quality is urgently needed to improve the safe utilization of marginal livers. Ex-situ machine perfusion approaches, such as HOPE, are therefore likely to increase the number of useable liver grafts.

Exercise training as an intervention for frailty in cirrhotic patients on the liver transplant waiting list: A systematic review.

BACKGROUND: The existing literature suggests that exercise for cirrhotic patients is safe and favours significant improvement to their physical capacity. However, exercise training for this population and how to deliver activities, especially in severe stages of the disease and while waiting for a liver transplant (LT), remain undefined. AIM: To review the existing exercise prescriptions for cirrhotic patients on the waiting list for LT, their results for frailty evolution and their effect on clinical outcomes. METHODS: A systematic review was performed following the Preferred Reporting Review and Meta-Analysis guidelines and searching the PubMed, MEDLINE, and Scopus databases. The keyword "liver transplant" was used in combination with the free terms "frailty" and "exercise" for the literature review. Clinical studies that evaluated the effect of a regular training program, independent of supervision or the duration or intensity of physical exercise, in cirrhotic patients on the waiting list for LT were reviewed. The data on safe physical activity prescriptions following Frequency, Intensity, Time, and Type recommendations were extracted and summarised. RESULTS: Nine articles met the inclusion criteria for this review. Various instruments for frailty assessment were used, frequently in combination. Five studies prescribed physical activity for patients, one in-person and four to be performed remotely and unsupervised. The remaining four studies only used a self-report instrument to assess the level of physical activity. None reported adverse events related to exercise training. The exercise frequency mainly varied from daily to a minimum of twice per week. The intensity depended on frailty and included increasing levels of activity. The type of exercise was predominantly a combination of aerobic and resistance training. The duration of exercise varied from 4 to 12 wk. Three articles evaluated the effect of the exercise program on clinical outcomes, reporting a reduction in 90-d readmission rates post-transplant and improved frailty scores, as well as improved survival of cirrhotic patients waiting for LT. CONCLUSION: Routine frailty assessment is essential for this population. Although more robust evidence is required, the prescription of exercise is safe and can improve patients' functional capacity, improving pre- and post-LT outcomes.

Establishing a HOPE Program in a Real-life Setting: A Brazilian Case Series.

Background: Although hypothermic oxygenated perfusion (HOPE) improves posttransplant outcomes, setting up machine perfusion programs may be subjected to specific obstacles under different conditions. This study aims to describe the establishment of HOPE in a real-life setting in Brazil. Methods: Extended criteria donors in donation after brain death organs preserved by HOPE were accepted for higher-risk candidates needing expedited transplantation, perceived as those who would benefit most from the technique because of its limited availability. Extended criteria donors was defined by the Eurotransplant criteria. High-risk transplant candidates were characterized by suboptimal surgical conditions related to the recipient or the procedure. Results: Six HOPE-preserved grafts were transplanted from February 2022 to August 2022. The mean donor risk index was 1.7 (SD 0.5). One organ was severely steatotic, and 3 had an anticipated cold ischemia time above 12 h. Recipients' mean model for end-stage liver disease was 28.67 (SD 6.79), with 1 case of retransplant, 1 of refractory ascites, and 1 of acute-on-chronic liver failure. The mean cold ischemia time was 5 h 42 min (SD 82 min), HOPE 6 h 3 min (SD 150 min), and total preservation time 11 h 46 min (SD 184 min). No case had early allograft dysfunction. The mean length of hospital stay was 10 d with 100% graft and patient survival and no ischemic cholangiopathies at a median follow-up of 15 mo (min 12, max 18). Costs and country-specific legal regulations for device utilization were the major hurdles to implementing the program. Conclusion: We presented a pathway to introduce and rationalize the use of HOPE in a scenario of challenging donor-recipient matching with good results. These findings may aid in implementing machine perfusion programs, especially in settings with limited resources or complex transplant logistics.

Eleven hours of hypothermic oxygenated machine perfusion (HOPE) for complex liver retransplantation: A case report.

This case report describes the longest reported HOPE treatment ever for an extended criteria donor organ in donation after brain death performed to enable the transplantation of a surgically complex retransplant case. Although further evidence is required, HOPE may facilitate liver retransplantation, expanding the donor organ pool and reducing time constraints on the operation.

Extended criteria brain-dead organ donors: Prevalence and impact on the utilisation of livers for transplantation in Brazil.

BACKGROUND: Despite its association with higher postoperative morbidity and mortality, the use of extended criteria donor (ECD) livers for transplantation has increased globally due to the high demand for the procedure. AIM: To investigate the prevalence of ECD in donation after brain death (DBD) and its impact on organ acceptance for transplantation. METHODS: Retrospective analysis of DBD organ offers for liver transplantation between 2017 and 2020 in a high-volume transplant centre. The incidence of the Eurotransplant risk factors to define an ECD (ET-ECD) among DBD donors and the likelihood of organ acceptance over the years were analysed. The relationship between organ refusal for transplantation, the occurrence, and the number of ET-ECD was assessed by simple and multiple logistic regression adjustment. RESULTS: A total of 1619 organ donors were evaluated. Of these, 78.31% (n = 1268) had at least one ET-ECD criterion. There was an increase in the acceptance of ECD DBD organs for transplantation (1 criterion: from 23.40% to 31.60%; 2 criteria: from 13.10% to 27.70%; 3 criteria: From 6.30% to 13.60%). For each addition of one ET-ECD variable, the estimated chance of organ refusal was 64.4% higher (OR 1.644, 95%CI 1.469-1.839, P < 0.001). Except for the donor serum sodium > 165 mmol/L (P = 0.310), all ET-ECD criteria increased the estimated chance of organ refusal for transplantation. CONCLUSION: A high prevalence of ECD DBD was observed. Despite the increase in their utilisation, the presence and the number of extended donor criteria were associated with an increased likelihood of their refusal for transplantation.

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.

Current and future perspectives on acute-on-chronic liver failure: Challenges of transplantation, machine perfusion, and beyond.

Acute-on-chronic liver failure (ACLF) is a syndrome that occurs in patients with chronic liver disease and is characterized by acute decompensation, organ failure and high short-term mortality. Partially due to the lack of universal diagnostic criteria, the actual ACLF prevalence remains unclear; nevertheless, it is expected to be a highly prevalent condition worldwide. Earlier transplantation is an effective protective measure for selected ACLF patients. Besides liver trans-plantation, diagnosing and treating precipitant events and providing supportive treatment for organ failures are currently the cornerstone of ACLF therapy. Although new clinical specific therapies have been researched, more studies are necessary to assess safety and efficacy. Therefore, future ACLF management strategies must consider measures to improve access to liver transplantation because the time window for this life-saving therapy is frequently narrow. Thus, an urgent and global discussion about allocation and prioritization for transplantation in critically ill ACLF patients is needed because there is evidence suggesting that the current model may not portray their waitlist mortality. In addition, while donor organ quality is meant to be a prognostic factor in the ACLF setting, recent evidence suggests that machine perfusion of the liver may be a safe tool to improve the donor organ pool and expedite liver transplantation in this scenario.

Risk adjusted assessment of individual surgeon's pancreatic fistula outcomes.

BACKGROUND: Post-operative pancreatic fistula (POPF) is a major cause of morbidity following pancreatoduodenectomy. The risk of POPF varies between individuals and thus assessment without risk adjustment is crude. However, despite the availability of numerous scores to determine risk, no study has provided a risk adjusted assessment of POPF outcomes. METHODS: The observed and risk adjusted occurrence of POPF from consecutive patients operated upon by eight surgeons were recorded. Surgeons varied in experience from newly appointed (n = 5) to established (n = 3). CUSUM (cumulative sum) analysis was used to assess performance. RESULTS: 104 POPF occurred among 519 patients (20.0%). The occurrence of POPF was significantly lower among experienced surgeons (20/186, 10.7% vs 84/333, 25.2%; p < 0.001). Following risk adjustment surgeons observed 16.6 fewer to 6.5 excess POPF per 100 patients than predicted. Analysis of the CUSUM plots demonstrated the experienced surgeons performed steadily with a gradual reduction in observed POPF compared to what was predicted. The new surgeon's performance was less consistent and evidence of a learning curve was observed with steady improvement occurring after 50-70 patients. CONCLUSIONS: Risk adjusted assessment of POPF demonstrates differences between experienced and less experienced surgeons. This method could be used to audit practice and observe effects of changes to technique.

Manipulation of Lipid Metabolism During Normothermic Machine Perfusion: Effect of Defatting Therapies on Donor Liver Functional Recovery.

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 1ß). 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.

Retrieval Practice or Overall Donor and Recipient Risk: What Impacts on Outcomes After Donation After Circulatory Death Liver Transplantation in the United Kingdom?

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.

Multivariable analysis of predictors of unplanned hospital readmission after pancreaticoduodenectomy: development of a validated risk score.

BACKGROUND: Unplanned hospital readmission after pancreaticoduodenectomy (PD) is usually due to surgical complications and has significant clinical and economic impact. This study developed a risk score to predict 30-day readmission after PD. METHODS: Patients undergoing PD between 2009 and 2016 were reviewed from a prospective database. Predictors of readmission were identified using a multivariable logistic regression model, from which a points-based risk scoring system was derived. RESULTS: 81 of 518 patients (15.6%) were readmitted within 30 days. History of cardiac disease ([odds ratio] OR = 2.12; 95% CI: 1.12-4.56), CRP>140 mg/L on post-operative day 3 (OR = 2.34; 95% CI: 1.37-4.35) and comprehensive complication index >14 (OR = 1.74; 95% CI: 1.03-2.85) were independent predictors of readmission. The regression coefficients were used to generate a risk score with excellent calibration (p = 0.917) and good discrimination (c-index = 0.65; 95% CI: 0.58-0.71; p < 0.001). Patients were categorised as low, moderate and high risk, with readmission rates of 6.4%, 13.4% and 23.0% respectively (p < 0.001). CONCLUSION: The risk score identifies patients at high risk of readmission after pancreaticoduodenectomy. Such patients may benefit from pre-discharge imaging and/or enhanced follow-up, which may potentially reduce the impact of readmissions.

An effective protocol for pharmacological defatting of primary human hepatocytes which is non-toxic to cholangiocytes or intrahepatic endothelial cells.

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 ß-oxidation whilst being non-toxic to PHH, HIEC or cholangiocytes.

Ex situ machine perfusion as a tool to recondition steatotic donor livers: Troublesome features of fatty livers and the role of defatting therapies. A systematic review.

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.