Grade of deceased donor liver macrovesicular steatosis impacts graft and recipient outcomes more than the Donor Risk Index

Indocyanine green: A novel marker for assessment of graft quality during ex situ normothermic machine perfusion of human livers

BACKGROUND

Ex situ machine perfusion facilitates the assessment of livers prior to transplantation. However, currently available markers of liver function poorly predict long-term graft function. Indocyanine green (ICG) is a liver-specific dye which, although common in vivo, has never been comprehensively evaluated for the assessment of graft quality during ex situ machine perfusion. This study aimed to assess the utility of ICG in the ex situ setting.

METHODS

Using a customized long-term perfusion system, human livers that were not suitable for transplantation were perfused using a red cell-based perfusate. ICG was delivered into the perfusate on days 0, 1, and 4 to assess ICG clearance (spectrophotometric absorbance at 805 nm) and ICG fluorescence (near-infrared camera).

RESULTS

Sixteen partial livers were perfused for a median duration of 172 h (7.2 days). On day 0, the median ICG perfusate disappearance rate (PDR) was 7.5%/min and the median ICG retention at 15 min was 9.9%. Grafts that survived ≥7 days had a significantly higher median ICG PDR on day 0 (14.5%/min vs. 6.5%/min, p = 0.005) but not on days 1 or 4. ICG perfusion demonstrated that long-surviving grafts had a significantly lower median red-value (89.8 vs. 118.6, p = 0.011) and a significantly lower median blue-value (12.9 vs. 22.6, p = 0.045) than short-surviving grafts.

CONCLUSION

ICG is a novel marker for the assessment of liver function during ex situ normothermic machine perfusion. ICG PDR and quantitative ICG perfusion can distinguish between long- and short-surviving grafts and demonstrate the utility of ICG in the assessment of graft quality prior to transplant.

Steatotic Donor Transplant Livers: Preservation Strategies to Mitigate against Ischaemia-Reperfusion Injury

Liver transplantation (LT) is the only definitive treatment for end-stage liver disease, yet the UK has seen a 400% increase in liver disease-related deaths since 1970, constrained further by a critical shortage of donor organs. This shortfall has necessitated the use of extended criteria donor organs, including those with evidence of steatosis. The impact of hepatic steatosis (HS) on graft viability remains a concern, particularly for donor livers with moderate to severe steatosis which are highly sensitive to the process of ischaemia-reperfusion injury (IRI) and static cold storage (SCS) leading to poor post-transplantation outcomes. This review explores the pathophysiological predisposition of steatotic livers to IRI, the limitations of SCS, and alternative preservation strategies, including novel organ preservation solutions (OPS) and normothermic machine perfusion (NMP), to mitigate IRI and improve outcomes for steatotic donor livers. By addressing these challenges, the liver transplant community can enhance the utilisation of steatotic donor livers which is crucial in the context of the global obesity crisis and the growing need to expand the donor pool.

Overcoming the hurdles of steatotic grafts in liver transplantation: Insights into survival and prognostic factors

With increasing metabolic dysfunction-associated steatotic liver disease, the use of steatotic grafts in liver transplantation (LT) and their impact on postoperative graft survival (GS) needs further exploration. Analyzing adult LT recipient data (2002-2022) from the United Network for Organ Sharing database, outcomes of LT using steatotic (≥30% macrosteatosis) and nonsteatotic donor livers, donors after circulatory death, and standard-risk older donors (age 45-50) were compared. GS predictors were evaluated using Kaplan-Meier and Cox regression analyses. Of the 35,345 LT donors, 8.9% (3,155) were fatty livers. The initial 30-day postoperative period revealed significant challenges with fatty livers, demonstrating inferior GS. However, the GS discrepancy between fatty and nonfatty livers subsided over time ( p = 0.10 at 5 y). Long-term GS outcomes showed comparable or even superior results in fatty livers relative to nonsteatotic livers, conditional on surviving the initial 90 postoperative days ( p = 0.90 at 1 y) or 1 year ( p = 0.03 at 5 y). In the multivariable Cox regression analysis, the high body surface area (BSA) ratio (≥1.1) (HR 1.42, p = 0.02), calculated as donor BSA divided by recipient BSA, long cold ischemic time (≥6.5 h) (HR 1.72, p < 0.01), and recipient medical condition (intensive care unit hospitalization) (HR 2.53, p < 0.01) emerged as significant adverse prognostic factors. Young (<40 y) fatty donors showed a high BSA ratio, diabetes, and intensive care unit hospitalization as significant indicators of a worse prognosis ( p < 0.01). Our study emphasizes the initial postoperative 30-day survival challenge in LT using fatty livers. However, with careful donor-recipient matching, for example, avoiding the use of steatotic donors with long cold ischemic time and high BSA ratios for recipients in the intensive care unit, it is possible to enhance immediate GS, and in a longer time, outcomes comparable to those using nonfatty livers, donors after circulatory death livers, or standard-risk older donors can be anticipated. These novel insights into decision-making criteria for steatotic liver use provide invaluable guidance for clinicians.

Effectiveness of metformin for the reversal of cold-ischemia-induced damage in hepatosteatosis

BACKGROUND

Primary dysfunction and rejection are more common in donor liver tissues with steatosis. AMP-activated protein kinase (AMPK) assumes organ-protective functions during ischemia. Metformin was used for the activation of AMPK in hepatocytes. The aim of this study is to investigate the effectiveness of metformin administration for the reversal of cold-ischemia-induced damage in hepatosteatosis.

MATERIAL AND METHODS

Seven-week-old C7BL56 male-mice (n = 109) were separated into four groups depending on diet type and metformin use. A specific diet model was followed for 10 weeks to induce hepatosteatosis. A group of the animals was administered with metformin for the last four weeks via oral gavage. After resection, the liver tissues were perfused and kept for 0-6-12-24 h in the UW solution. Histopathological examinations were performed, and Western blot was utilized to analyze p-AMPK and AMPK expression levels.

RESULTS

Hepatosteatosis decreased significantly with metformin. The steatotic liver group had more prominent pericentral inflammation, necrosis as well as showing a decreased and more delayed AMPK response than the non-fat group. All these alterations could be corrected using metformin.

CONCLUSION

Metformin can increase the resistance of livers with hepatosteatosis to cold-ischemia-induced damage, which in turn may pave the way for successful transplantation of fatty living-donor livers.

Improved assessment of donor liver steatosis using Banff consensus recommendations and deep learning algorithms

BACKGROUND & AIMS

The Banff Liver Working Group recently published consensus recommendations for steatosis assessment in donor liver biopsy, but few studies reported their use and no automated deep-learning algorithms based on the proposed criteria have been developed so far. We evaluated Banff recommendations on a large monocentric series of donor liver needle biopsies by comparing pathologists' scores with those generated by convolutional neural networks (CNNs) we specifically developed for automated steatosis assessment.

METHODS

We retrospectively retrieved 292 allograft liver needle biopsies collected between January 2016 and January 2020 and performed steatosis assessment using a former intra-institution method (pre-Banff method) and the newly introduced Banff recommendations. Scores provided by pathologists and CNN models were then compared, and the degree of agreement was measured with the intraclass correlation coefficient (ICC).

RESULTS

Regarding the pre-Banff method, poor agreement was observed between the pathologist and CNN models for small droplet macrovesicular steatosis (ICC: 0.38), large droplet macrovesicular steatosis (ICC: 0.08), and the final combined score (ICC: 0.16) evaluation, but none of these reached statistically significance. Interestingly, significantly improved agreement was observed using the Banff approach: ICC was 0.93 for the low-power score (p <0.001), 0.89 for the high-power score (p <0.001), and 0.93 for the final score (p <0.001). Comparing the pre-Banff method with the Banff approach on the same biopsy, pathologist and CNN model assessment showed a mean (±SD) percentage of discrepancy of 26.89 (±22.16) and 1.20 (±5.58), respectively.

CONCLUSIONS

Our findings support the use of Banff recommendations in daily practice and highlight the need for a granular analysis of their effect on liver transplantation outcomes.

IMPACT AND IMPLICATIONS

We developed and validated the first automated deep-learning algorithms for standardized steatosis assessment based on the Banff Liver Working Group consensus recommendations. Our algorithm provides an unbiased automated evaluation of steatosis, which will lay the groundwork for granular analysis of steatosis's short- and long-term effects on organ viability, enabling the identification of clinically relevant steatosis cut-offs for donor organ acceptance. Implementing our algorithm in daily clinical practice will allow for a more efficient and safe allocation of donor organs, improving the post-transplant outcomes of patients.

Focusing on Ischemic Reperfusion Injury in the New Era of Dynamic Machine Perfusion in Liver Transplantation

Liver transplantation is the most effective treatment for end-stage liver disease. Transplant indications have been progressively increasing, with a huge discrepancy between the supply and demand of optimal organs. In this context, the use of extended criteria donor grafts has gained importance, even though these grafts are more susceptible to ischemic reperfusion injury (IRI). Hepatic IRI is an inherent and inevitable consequence of all liver transplants; it involves ischemia-mediated cellular damage exacerbated upon reperfusion and its severity directly affects graft function and post-transplant complications. Strategies for organ preservation have been constantly improving since they first emerged. The current gold standard for preservation is perfusion solutions and static cold storage. However, novel approaches that allow extended preservation times, organ evaluation, and their treatment, which could increase the number of viable organs for transplantation, are currently under investigation. This review discusses the mechanisms associated with IRI, describes existing strategies for liver preservation, and emphasizes novel developments and challenges for effective organ preservation and optimization.

Implementation of a liver health check in people with type 2 diabetes

As morbidity and mortality related to potentially preventable liver diseases are on the rise globally, early detection of liver fibrosis offers a window of opportunity to prevent disease progression. Early detection of non-alcoholic fatty liver disease allows for initiation and reinforcement of guidance on bodyweight management, risk stratification for advanced liver fibrosis, and treatment optimisation of diabetes and other metabolic complications. Identification of alcohol-related liver disease provides the opportunity to support patients with detoxification and abstinence programmes. In all patient groups, identification of cirrhosis ensures that patients are enrolled in surveillance programmes for hepatocellular carcinoma and portal hypertension. When considering early detection strategies, success can be achieved from applying ad-hoc screening for liver fibrosis in established frameworks of care. Patients with type 2 diabetes are an important group to consider case findings of advanced liver fibrosis and cirrhosis, as up to 19% have advanced fibrosis (which is ten times higher than the general population) and almost 70% have non-alcoholic fatty liver disease. Additionally, patients with type 2 diabetes with alcohol use disorders have the highest proportion of liver-related morbidity of people with type 2 diabetes generally. Patients with type 2 diabetes receive an annual diabetes review as part of their routine clinical care, in which the health of many organs are considered. Yet, liver health is seldom included in this review. This Viewpoint argues that augmenting the existing risk stratification strategy with an additional liver health check provides the opportunity to detect advanced liver fibrosis, thereby opening a window for early interventions to prevent end-stage liver disease and its complications, including hepatocellular carcinoma.

Deep Learning-Based Survival Analysis for Receiving a Steatotic Donor Liver Versus Waiting for a Standard Liver

BACKGROUND

An emerging strategy to expand the donor pool is the use of a steatotic donor liver (SDLs; ≥ 30% macrosteatosis on biopsy). With the obesity epidemic and prevalence of nonalcoholic fatty liver disease, SDLs have been reported in 59% of all deceased donors. Many potential candidates need to decide whether to accept an SDL offer or remain on the waitlist for a nonsteatotic donor liver (non-SDL). The objective of this study was to compare the survival of accepting an SDL vs using a non-SDL after waiting various times.

METHODS

Using data from the United States' organ procurement and transplantation network, deep survival learning predictive models were built to compare post-decision survival after accepting an SDL vs waiting for a non-SDL. The comparison subjects contain simulated 20,000 different scenarios of a candidate either accepting an SDL immediately or receiving a non-SDL after waiting various times. The research variables were selected using the LASSO-Cox and Random Survival Forest (RSF) models. The Cox proportional hazards and RSF models were also comparatively included for survival prediction. In addition, personalized survival curves for randomly selected candidates were generated.

RESULT

Deep survival learning outperformed Cox proportional hazards and RSF in predicting the survival of liver transplants. Among the simulations, 25% to 30% of scenarios demonstrated a higher 3-year survival post-decision for candidates accepting an SDL than waiting and receiving a non-SDL. The difference was only 1.43% in 3-year survival post-decision between accepting an SDL and waiting 260 days (mean waitlist time) for a non-SDL. As the number of days on the waitlist increases, the difference in survival between accepting SDLs and waiting for non-SDLs decreases.

CONCLUSIONS

Appropriately used SDLs could expand the donor pool and relieve the candidates' unmet need for donor livers, which presents long-term survival benefits for recipients.

Liver transplantation in Latin America: reality and challenges

Healthcare systems in Latin America are broadly heterogeneous, but all of them are burdened by a dramatic rise in liver disease. Some challenges that these countries face include an increase in patients requiring a transplant, insufficient rates of organ donation, delayed referral, and inequitable or suboptimal access to liver transplant programs and post-transplant care. This could be improved by expanding the donor pool through the implementation of education programs for citizens and referring physicians, as well as the inclusion of extended criteria donors, living donors and split liver transplantation. Addressing these shortcomings will require national shifts aimed at improving infrastructure, increasing awareness of organ donation, training medical personnel, and providing equitable access to care for all patients.

de Moraes T, Fragoso GR. Prospective Study to Analyze the Concordance Between a Standardized Visual Method With Pathology to stratify Nonalcoholic Fatty Liver Disease in Cadaveric Liver Grafts Evaluated for Transplantation

Background

The main challenge of liver transplantation is the discrepancy in demand and availability. Marginal grafts or full organs from donors with expansion criteria have been considered to reduce the shortage and assist a greater number of patients. Nonalcoholic fatty liver disease (NAFLD) is one of the most important defining criteria for expanded criteria organs. The present study proposes that an organized visual analysis method could correctly identify and classify NAFLD and organ viability without the need for liver biopsy and its logistical concerns.

Methods

Pictures from the grafts were taken at a standardized method (same distance, light conditions, and register device) before and after the perfusion. The visual liver score (VLS) was applied by transplant surgeons; biopsies of the grafts were analyzed by a pathologist in a double-blind design. Score performance and interobserver agreement for NAFLD detection and grading, as graft viability evaluation, were calculated.

Results

Fifty-seven grafts were analyzed. At least 1 previous expansion criterion was presented by 59.64% of donors. The prevalence of NAFLD was 94.73%, with 31.57% borderline nonalcoholic steatohepatitis and 5.26% nonalcoholic steatohepatitis. Steatosis was identified with 48.68% (preperfusion) and 64.03% (postperfusion) accuracy. NAFLD stratification was performed with 49.53% (preperfusion) and 46.29% (postperfusion) accuracy. Viability related to NAFLD was identified with 51.96% (preperfusion) and 48.52% (postperfusion) accuracy. Interobserver agreement was moderate for total VLS and poor for individual components of VLS.

Conclusions

Although a standardized method was not reliable enough for visual evaluation of NALFD compared with pathology, efforts should be made to expand access to biopsy. Further studies are needed to understand whether the VLS needs to be adapted or even excluded in the liver transplant scenario, to assess the importance of ectoscopy related to posttransplant clinical outcomes, and to determine its role in graft selection.

Japanese national survey on declined liver allografts from brain-dead donors: High decline rate but promising outcomes in allografts with moderate steatosis

Aim

Liver allografts from brain-dead donors, which were declined and were eventually not transplanted due to accompanying marginal factors, have never been surveyed in Japan. We surveyed the declined allografts and discussed the graft potential focusing on various marginal factors.

Methods

We collected data on brain-dead donors between 1999 and 2019 from the Japan Organ Transplant Network. We divided their liver allografts into declined (nontransplanted) and transplanted ones, and then characterized declined ones focusing on their timepoints of decline and accompanying marginal factors. For each marginal factor, we calculated the decline rate from the number of declined and transplanted allografts, and assessed the 1-year graft survival rate from transplanted allografts.

Results

A total of 571 liver allografts were divided into 84 (14.7%) declined and 487 (85.3%) transplanted ones. In the declined allografts, a majority was declined after laparotomy (n = 55, 65.5%), most of which had steatosis and/or fibrosis (n = 52). Out of the moderate steatotic (without F ≥ 2 fibrosis) allografts (n = 33), 21 were declined and 12 were transplanted, leading to a 63.6% decline rate. The latter 12 achieved a 92.9% 1-year graft survival rate after transplantation. Comparison of donor background showed no significant difference between the declined and transplanted allografts.

Conclusion

Pathological abnormalities of steatosis/fibrosis seem to be the most common donor factor leading to graft decline in Japan. Allografts with moderate steatosis were highly declined; however, transplanted ones achieved promising outcomes. This national survey highlights the potential utility of liver allografts with moderate steatosis.

How to Preserve Steatotic Liver Grafts for Transplantation

Liver allograft steatosis is a significant risk factor for postoperative graft dysfunction and has been associated with inferior patient and graft survival, particularly in the case of moderate or severe macrovesicular steatosis. In recent years, the increasing incidence of obesity and fatty liver disease in the population has led to a higher proportion of steatotic liver grafts being used for transplantation, making the optimization of their preservation an urgent necessity. This review discusses the mechanisms behind the increased susceptibility of fatty livers to ischemia-reperfusion injury and provides an overview of the available strategies to improve their utilization for transplantation, with a focus on preclinical and clinical evidence supporting donor interventions, novel preservation solutions, and machine perfusion techniques.

Gamma-glutamyltransferase predicts macrovesicular liver graft steatosis - an analysis of discarded liver allografts in Finland

OBJECTIVE

Liver-transplantation activity is limited by the shortage of grafts. Donor-liver macrovesicular steatosis predisposes to ischemia-reperfusion injury and is associated with reduced graft survival. The increasing prevalence of fatty-liver disease underlines the importance of identifying macrovesicular steatosis in potential donor livers. We analyzed liver grafts discarded for transplantation, and particularly the role of gamma-glutamyltransferase (GGT) in predicting graft steatosis.

METHODS

One-hundred sixty rejected cadaveric-donor liver grafts were studied. Donor selection was based on clinical data, and macroscopic graft inspection. Discarded grafts were biopsied at procurement of non-liver organs.

RESULTS

The most common reasons for discarding the graft were abnormal liver tests, ultrasound-verified steatosis and history of harmful alcohol use. GGT correlated moderately with macrovesicular steatosis (r = 0.52, p < 0.001), but poorly with microvesicular steatosis (r = 0.36, p < 0.001). Increased correlation between GGT and macrovesicular steatosis was observed among alcohol abusers (r = 0.67, p < 0.001). Area under the curve (AUC) of GGT for predicting >30% macrovesicular steatosis was 0.79 (95% CI 0.71-0.88), and for >60% steatosis, 0.79 (95% CI 0.68-0.90). The optimal GGT-cut off for detecting >30% and >60% macrovesicular steatosis were, respectively, 66 U/L (sensitivity 76% and specificity 68%) and 142 U/L (sensitivity 66% and specificity 83%). Among alcohol users, a GGT value >90 U/L showed 100% sensitivity for >60% macrovesicular steatosis. AUC for GGT in predicting fibrosis Stages 2-4 was 0.82 (95% CI 0.71-0.92, p < 0.001, optimal cut off 68, sensitivity 92%, specificity 61%).

CONCLUSIONS

Abnormal liver values, steatosis and harmful alcohol use were the main reasons for discarding liver-graft offers in Finland. GGT proved useful in predicting moderate and severe liver graft macrovesicular steatosis.

Characterization of hepatic steatosis using controlled attenuation parameter and MRI-derived proton density fat fraction in living donor liver transplantation

BACKGROUND

The increasingly favorable outcomes of live donor liver transplant warrant development of screening techniques to expand current donor pool. Transient elastography (TE) with controlled attenuation parameter (CAP) is accessible and has promising diagnostic performance in non-obese individuals. Here, we demonstrate its utility in grading donor steatosis for risk assessment in living liver donors (LLD).

STUDY DESIGN

In a prospective study of LLD and recipients, accuracy was determined using MRI-derived proton density fat fraction (PDFF) as reference.

RESULTS

One hundred and one LLD underwent TE, 95 of whom had available PDFF. Median CAP and MRI-PDFF were 233 dB/m (206-270) and 2.9% (2.3-4.0), respectively. A CAP threshold of 270 dB/m captured all steatosis which was present in 13 (13%) LLD (AUROC .942, 100% sensitivity and 83% specificity). Performance further improved when excluding obese LLD and limiting analysis to M-probe (AUROC .971 and .974, respectively, with 87% specificity). There was no difference in CAP and MRI-PDFF between LLD and nondonors (P = .26 and .21, respectively). Early allograft dysfunction was observed in one recipient (CAP 316, PDFF 9.5%), zero underwent retransplant, and one died from sepsis.

CONCLUSION

The specific role of CAP in living liver donation warrants further study, beginning with its use as screening tool across peripheral clinics.

How useful is the machine perfusion in liver transplantation? An answer from a national survey

Machine perfusion (MP) has been shown worldwide to offer many advantages in liver transplantation, but it still has some gray areas. The purpose of the study is to evaluate the donor risk factors of grafts, perfused with any MP, that might predict an ineffective MP setting and those would trigger post-transplant early allograft dysfunction (EAD). Data from donors of all MP-perfused grafts at six liver transplant centers have been analyzed, whether implanted or discarded after perfusion. The first endpoint was the negative events after perfusion (NegE), which is the number of grafts discarded plus those that were implanted but lost after the transplant. A risk factor analysis for NegE was performed and marginal grafts for MP were identified. Finally, the risk of EAD was analyzed, considering only implanted grafts. From 2015 to September 2019, 158 grafts were perfused with MP: 151 grafts were implanted and 7 were discarded after the MP phase because they did not reach viability criteria. Of 151, 15 grafts were lost after transplant, so the NegE group consisted of 22 donors. In univariate analysis, the donor risk index >1.7, the presence of hypertension in the medical history, static cold ischemia time, and the moderate or severe macrovesicular steatosis were the significant factors for NegE. Multivariate analysis confirmed that macrosteatosis >30% was an independent risk factor for NegE (odd ratio 5.643, p = 0.023, 95% confidence interval, 1.27–24.98). Of 151 transplanted patients, 34% experienced EAD and had worse 1- and 3-year-survival, compared with those who did not face EAD (NoEAD), 96% and 96% for EAD vs. 89% and 71% for NoEAD, respectively (p = 0.03). None of the donor/graft characteristics was associated with EAD even if the graft was moderately steatotic or fibrotic or from an aged donor. For the first time, this study shows that macrovesicular steatosis >30% might be a warning factor involved in the risk of graft loss or a cause of graft discard after the MP treatment. On the other hand, the MP seems to be useful in reducing the donor and graft weight in the development of EAD.

Growing challenge of post-liver transplantation non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is one of the leading causes of chronic liver disease, cirrhosis, and hepatocellular carcinoma worldwide, with an estimated prevalence of 25%. Post-liver transplantation (LT) recurrent or de novo hepatic steatosis is a common complication in recipients, irrespective of transplantation indication. Risk factors for graft steatosis mainly include obesity, immunosuppression, donor steatosis, and genetic factors. Liver transplant recipients are at high risk of developing insulin resistance, new-onset diabetes, and post-transplantation metabolic syndrome that is highly associated with immunosuppressive treatment. Post-LT NAFLD is often underdiagnosed due to the poor sensitivity of most routine imaging methods. The gold standard for the diagnosis of hepatic steatosis is liver biopsy, which is, however, limited to more complex cases due to its invasive nature. There is no approved pharmacotherapy in NAFLD. Lifestyle modification remains the cornerstone in NAFLD treatment. Other treatment strategies in post-LT NAFLD include lifestyle modifications, pharmacotherapy, bariatric surgery, and tailored immunosuppression. However, these approaches originate from recommendations in the general population, as there is scarce data regarding the safety and efficacy of current management strategies for NAFLD in liver transplant patients. Future prospective studies are required to achieve tailored treatment for these patients.

Normothermic Machine Perfusion—Improving the Supply of Transplantable Livers for High-Risk Recipients

The effectiveness of liver transplantation to cure numerous diseases, alleviate suffering, and improve patient survival has led to an ever increasing demand. Improvements in preoperative management, surgical technique, and postoperative care have allowed increasingly complicated and high-risk patients to be safely transplanted. As a result, many patients are safely transplanted in the modern era that would have been considered untransplantable in times gone by. Despite this, more gains are possible as the science behind transplantation is increasingly understood. Normothermic machine perfusion of liver grafts builds on these gains further by increasing the safe use of grafts with suboptimal features, through objective assessment of both hepatocyte and cholangiocyte function. This technology can minimize cold ischemia, but prolong total preservation time, with particular benefits for suboptimal grafts and surgically challenging recipients. In addition to more physiological and favorable preservation conditions for grafts with risk factors for poor outcome, the extended preservation time benefits operative logistics by allowing a careful explant and complicated vascular reconstruction when presented with challenging surgical scenarios. This technology represents a significant advancement in graft preservation techniques and the transplant community must continue to incorporate this technology to ensure the benefits of liver transplant are maximized.

Development of a risk score model for 1‐year graft loss after adult deceased donor liver transplantation in Japan based on a 20‐year nationwide cohort

Aim

Using nationwide data collected over the past 20 years, we aimed to investigate deceased donor liver transplantation (DDLT) outcomes to develop a unique risk model that can be used to establish a standard for organ acceptance in Japan.

Methods

Data were collected for 449 recipients aged ≥18 years who underwent DDLT between 1999 and 2019. Least absolute shrinkage and selection operator (LASSO) regression analysis was utilized to develop an original risk score model for 1‐year graft loss (termed the Japan Risk Index [JRI]). We developed risk indices according to recipient, donor, and surgery components (termed JRI‐R, D, and S, respectively). The JRI was validated via a 5‐fold cross‐validation. We also compared DDLT outcomes and risk indices among Era1 (−2011), Era2 (−2015), and Era3 (−2019).

Results

The 1‐year graft survival rate was 89.5% and improved significantly, reaching 84.7%, 87.6%, and 93.9% in Era1, Era2, and Era3, respectively. The JRI was calculated as JRI‐R (re‐transplantation, Model for End‐Stage Liver Disease score, medical condition in intensive care unit) × JRI‐D (age, catecholamine index, maximum sodium, maximum total bilirubin) × JRI‐S (total ischemic time) × 0.84. The risk model achieved a mean C‐statistic value of 0.81 in the validation analysis. The risk index was significantly lower in Era3 than in Era2.

Conclusion

Changes in the risk index over time indicated that avoiding risks contributed to the improved outcomes in Era3. The JRI is unique to adult DDLT in Japan and may be useful as a reference for organ acceptance in the future.

A Clinical Tool to Guide Selection and Utilization of Marginal Donor Livers With Graft Steatosis in Liver Transplantation

Supplemental Digital Content is available in the text.

Background.

Donor liver biopsy (DLBx) in liver transplantation provides information on allograft quality; however, predicting outcomes from these allografts remains difficult.

Methods.

Between 2006 and 2015, 16 691 transplants with DLBx were identified from the Standard Transplant Analysis and Research database. Cox proportional hazard regression analyses identified donor and recipient characteristics associated with 30-d, 90-d, 1-y, and 3-y graft survival. A composite model, the Liver Transplant After Biopsy (LTAB) score, was created. The Mini-LTAB was then derived consisting of only donor age, macrosteatosis on DLBx, recipient model for end-stage liver disease score, and cold ischemic time. Risk groups were identified for each score and graft survival was evaluated. P values <0.05 were considered significant.

Results.

The LTAB model used 14 variables and 5 risk groups and identified low-, mild-, moderate-, high-, and severe-risk groups. Compared with moderate-risk recipients, severe-risk recipients had increased risk of graft loss at 30 d (hazard ratio, 3.270; 95% confidence interval, 2.568-4.120) and at 1 y (2.258; 1.928-2.544). The Mini-LTAB model identified low-, moderate-, and high-risk groups. Graft survival in Mini-LTAB high-risk transplants was significantly lower than moderate- or low-risk transplants at all time points.

Conclusions.

The LTAB and Mini-LTAB scores represent guiding principles and provide clinically useful tools for the successful selection and utilization of marginal allografts in liver transplantation.

An Update on Usage of High-Risk Donors in Liver Transplantation

The ideal management for end stage liver disease, acute liver failure, and hepatocellular carcinoma (HCC), within specific criteria, is liver transplantation (LT). Over the years, there has been a steady increase in the candidates listed for LT, without a corresponding increase in the donor pool. Therefore, due to organ shortage, it has been substantially difficult to reduce waitlist mortality among patients awaiting LT. Thus, marginal donors such as elderly donors, steatotic donors, split liver, and donors after cardiac death (DCD), which were once not commonly used, are now considered. Furthermore, it is encouraging to see the passing of Acts, such as the HIV Organ Policy Equity (HOPE) Act, enabling further research and development in utilizing HIV grafts. Subsequently, the newer antivirals have aided in successful post-transplant period, especially for hepatitis C positive grafts. However, currently, there is no standardization, and protocols are center specific in the usage of marginal donors. Therefore, studies with longer follow ups are required to standardize its use.

Prediction of Graft Survival Post-liver Transplantation by L-GrAFT Risk Score Model, EASE Score, MEAF Scoring, and EAD

Background: Early allograft dysfunction (EAD) is correlated with poor patient or graft survival in liver transplantation. However, the power of distinct definitions of EAD in prediction of graft survival is unclear. Methods: This retrospective, single-center study reviewed data of 677 recipients undergoing orthotopic liver transplant between July 2015 and June 2020. The following EAD definitions were compared: liver graft assessment following transplantation (L-GrAFT) risk score model, early allograft failure simplified estimation score (EASE), model for early allograft function (MEAF) scoring, and Olthoff criteria. Risk factors for L-GrAFT₇ high risk group were evaluated with univariate and multivariable logistic regression analysis. Results: L-GrAFT₇ had a satisfied C-statistic of 0.87 in predicting a 3-month graft survival which significantly outperformed MEAF (C-statistic = 0.78, P = 0.01) and EAD (C-statistic = 0.75, P < 0.001), respectively. L-GrAFT₁₀, EASE was similar to L-GrAFT₇, and they had no statistical significance in predicting survival. Laboratory model for end-stage liver disease score and cold ischemia time are risk factors of L-GrAFT₇ high-risk group. Conclusion: L-GrAFT₇ risk score is capable for better predicting the 3-month graft survival than the MEAF and EAD in a Chinese cohort, which might standardize assessment of early graft function and serve as a surrogate endpoint in clinical trial.

A proof of concept study on real-time LiMAx CYP1A2 liver function assessment of donor grafts during normothermic machine perfusion

No single reliable parameter exists to assess liver graft function of extended criteria donors during ex-vivo normothermic machine perfusion (NMP). The liver maximum capacity (LiMAx) test is a clinically validated cytochromal breath test, measuring liver function based on 13CO2 production. As an innovative concept, we aimed to integrate the LiMAx breath test with NMP to assess organ function. Eleven human livers were perfused using NMP. After one hour of stabilization, LiMAx testing was performed. Injury markers (ALT, AST, miR-122, FMN, and Suzuki-score) and lactate clearance were measured and related to LiMAx values. LiMAx values ranged between 111 and 1838 µg/kg/h, and performing consecutive LiMAx tests during longer NMP was feasible. No correlation was found between LiMAx value and miR-122 and FMN levels in the perfusate. However, a significant inverse correlation was found between LiMAx value and histological injury (Suzuki-score, R = − 0.874, P < 0.001), AST (R = − 0.812, P = 0.004) and ALT (R = − 0.687, P = 0.028). Furthermore, a significant correlation was found with lactate clearance (R = 0.683, P = 0.043). We demonstrate, as proof of principle, that liver function during NMP can be quantified using the LiMAx test, illustrating a positive correlation with traditional injury markers. This new breath-test application separates livers with adequate cytochromal liver function from inadequate ones and may support decision-making in the safe utilization of extended criteria donor grafts.

Combined Effect of Deceased Donor Macrovesicular and Microvesicular Steatosis on Liver Transplantation Outcomes: Analysis of SRTR Data Between 2010 and 2018

BACKGROUND

Because of the rising prevalence of obesity, the use of steatotic grafts in orthotopic liver transplantation is becoming increasingly obligatory. The purpose of this study was to determine the relative distribution of microvesicular steatosis (MiS) burden across categories of macrovesicular steatosis (MaS) and the effect of biopsy-sourced MaS and MiS on graft failure, recipient death, and retransplantation.

METHODS

We performed a retrospective analysis of 13,889 adults with deceased donor liver transplantations from the Scientific Registry of Transplant Recipients between 2010 and 2018. Multivariable Cox proportional hazards models were run to examine the independent and combined effects of MaS and MiS on major transplantation outcomes.

RESULTS

Recipients had a mean age of 56.5 years and a body mass index (BMI) of 29.2 kg/m²; 70% were men, and 74% were non-Hispanic white. Considering the independent effect of MaS, recipients of livers with 30% to 60% MaS had 97% and 129%, 71% and 81%, 39% and 43%, and 40% and 19% increased risks of graft failure and death at 1 month, 3 months, 1 year, and 3 years post-transplantation, respectively. Considering the combined effects of MaS and MiS, 16% to 60% MaS increased the risk of graft failure and recipient death regardless of MiS burden within the first 3 months post-transplantation. These risks were also increased among recipients of livers with 5% to 15% MaS and the additional burden of 16% to 60% MiS.

CONCLUSIONS

Our findings suggest that risk threshold of adverse transplantation outcomes owing to steatosis appears to be lower than previously recognized and currently practiced. These risks must be weighed and mitigated against the duress of organ shortage and saving lives.

Assessment of Donor Liver Pathology Predicts Survival After Liver Transplantation: A Retrospective Cohort Study

BACKGROUND

The aims of this study were to investigate the pathologic manifestation of pretransplant biopsy and to provide an accurate assessment method for liver graft of China Donation after Citizen's Death (CDCD).

METHODS

A retrospective analysis was performed based on clinical and biopsy data of 96 CDCD liver transplantations completed between January 2012 and December 2017. The pretransplant pathologic sections were semiquantitatively scored according to Banff Schema recommendations on liver allograft pathology. Graft overall survival (OS) and early allograft dysfunction (EAD) rates were observed.

RESULTS

The histologic analysis of the 96 CDCD liver graft biopsy specimens was summarized, including portal area neutrophilic infiltrate, macrovesicular steatosis, microvesicular steatosis, and hepatocellular swelling. Among these pathologic characteristics, only portal area neutrophilic infiltrate ≥20% was an independent risk factor for graft survival, although it has limited effect on the recipient's short-term prognosis.

CONCLUSIONS

We found that portal area neutrophilic infiltrate ≥20% was an independent risk factors for long-term graft survival. According to this criterion, we can identify liver transplant recipients at risk for poor prognosis and make timely interventions.

Liver Transplantation With Grafts From Super Obese Donors

There are limited data on liver transplant (LT) outcomes with grafts from super obese donors. The present study aims to evaluate a unique cohort of recipients following LT using grafts from donors with body mass index (BMI) ≥50.

Methods

Patients receiving grafts from donors with BMI ≥50 and BMI <50 from 2010 to 2019 were identified. A 1:2 case-control match was conducted to compare outcomes between the groups. Survival was analyzed using the Kaplan-Meier curves.

Results

Six hundred sixty-five adult LTs were performed in the study period. Eighteen patients receiving a graft from a donor with BMI ≥50 were identified and matched to 36 patients receiving a graft from a donor with BMI <50. Grafts from male donors were significantly lower in the donor BMI ≥50 group when compared with the donor BMI <50 group (16.7% versus 66.7%, P = 0.001). Liver biopsy was performed in 77.8% of grafts in the donor BMI ≥50 group, whereas only in 38.8% of the grafts in the donor BMI <50 group (P = 0.007). Recipients in the donor BMI ≥50 group had a significantly higher diagnosis rate of hepatocellular carcinoma pretransplant versus the donor BMI <50 group (38.9% versus 8.3%, respectively; P = 0.006). Major complications within 30 d did not differ statistically between groups. Biliary complications within the first 30 d were equal among groups (16.7%). Subanalysis comparing the super obese donor group versus the nonobese donor group showed no differences in terms of postoperative complications, readmission rate, graft rejection, or major complications including the need for reoperation, retransplantation, or mortality. Graft and patient survival at 1-, 3-, and 5-y graft were similar between the donor BMI ≥50 group versus donor BMI <50 group (94%/89%/89% versus 88%/88%/88%, P = 0.89, and 94%/94%/94% versus 88%/88%/88%, P = 0.48, respectively).

Conclusions

LT with carefully selected grafts from super obese donors can be safely performed with outcomes comparable with non-super obese donor livers. Therefore, these types of grafts could represent a safe means to expand the donor pool.

The Propensity of the Human Liver to Form Large Lipid Droplets Is Associated with PNPLA3 Polymorphism, Reduced INSIG1 and NPC1L1 Expression and Increased Fibrogenetic Capacity

In nonalcoholic steatohepatitis animal models, an increased lipid droplet size in hepatocytes is associated with fibrogenesis. Hepatocytes with large droplet (Ld-MaS) or small droplet (Sd-MaS) macrovesicular steatosis may coexist in the human liver, but the factors associated with the predominance of one type over the other, including hepatic fibrogenic capacity, are unknown. In pre-ischemic liver biopsies from 225 consecutive liver transplant donors, we retrospectively counted hepatocytes with Ld-MaS and Sd-MaS and defined the predominant type of steatosis as involving ≥50% of steatotic hepatocytes. We analyzed a donor Patatin-like phospholipase domain-containing protein 3 (PNPLA3) rs738409 polymorphism, hepatic expression of proteins involved in lipid metabolism by RT-PCR, hepatic stellate cell (HSC) activation by α-SMA immunohistochemistry and, one year after transplantation, histological progression of fibrosis due to Hepatitis C Virus (HCV) recurrence. Seventy-four livers had no steatosis, and there were 98 and 53 with predominant Ld-MaS and Sd-MaS, respectively. In linear regression models, adjusted for many donor variables, the percentage of steatotic hepatocytes affected by Ld-MaS was inversely associated with hepatic expression of Insulin Induced Gene 1 (INSIG-1) and Niemann-Pick C1-Like 1 gene (NPC1L1) and directly with donor PNPLA3 variant M, HSC activation and progression of post-transplant fibrosis. In humans, Ld-MaS formation by hepatocytes is associated with abnormal PNPLA3-mediated lipolysis, downregulation of both the intracellular cholesterol sensor and cholesterol reabsorption from bile and increased hepatic fibrogenesis.

Changing trends in liver transplantation indications in Saudi Arabia: from hepatitis C virus infection to nonalcoholic fatty liver disease

Background

Several trend analyses on liver transplantation (LT) indications have been published in the U.S. and in other countries, but there are limited data on LT indication trends in Saudi Arabia (SA), especially since the availability of direct-acting antivirals (DAAs) treatment for hepatitis C virus (HCV). This study aimed to analyze trends in the frequency of LT indications among LT recipients in SA over a 19-year period and examine associations between etiologic-specific trends and clinicodemographic characteristics.

Methods

This retrospective study analyzed clinical and surgical data of adult patients (n = 1009) who underwent LT at the King Faisal Specialist Hospital & Research Center (Riyadh, SA) between 2001 and 2019. Spearman’s rank correlation, Poisson regression, and Joinpoint regression analysis were employed to assess changes in LT etiologic trends.

Results

In the first period (2001–2010), the main LT indications were HCV (41.9%) and hepatitis B virus (HBV) (21.1%), but nonalcoholic steatohepatitis (NASH) (29.7%) surpassed HCV (23.7%) as the leading LT indication in the second period (2011–2019); and the trends were significant in correlation analyses [incidence rate ratio (IRR) = 1.09 (1.06–1.13) for NASH; IRR = 0.93 (0.91–0.95) for HCV]. In the Joinpoint regression analysis, increases in NASH from 2006 to 2012 (+ 32.1%) were statistically significant, as were the decreases in HCV from 2004 to 2007 (− 19.6%) and from 2010 to 2019 (− 12.1%). Similar patterns were observed in LT etiological comparisons before and after the availability of DAAs and within hepatocellular carcinoma stratifications.

Conclusions

Trends in the epidemiology of LT indications among LT recipients in SA have changed over a 19-year period. Most notably, NASH has eclipsed HCV in the country due to the effective treatment strategies for HCV. These trends in NASH now need an aggressive public health response to minimize and avert future onset of additional clinical and economic strains on health care systems and LT centers in SA.

Changing Trends in Liver Transplantation: Challenges and Solutions

Despite improvements in postliver transplant outcomes through refinements in perioperative management and surgical techniques, several changing trends in liver transplantation have presented challenges. Mortality on the waitlist remains high. In the United States, Europe, and the United Kingdom, there is an increasing need for liver transplantation, primarily as a result of increased incidence of nonalcoholic steatohepatitis-related cirrhosis and cancer indications. Meanwhile, donor suitability has decreased, as donors are often older and have more comorbidities. Despite a mismatch between organ need and availability, many organs are discarded. Notwithstanding this, many solutions have been developed to overcome these challenges. Innovative techniques in allograft preservation, viability assessment, and reconditioning have allowed the use of suboptimal organs with adequate results. Refinements in surgical procedures, including live donor liver transplantations, have increased the organ pool and are decreasing the time and mortality on the waitlist. Despite many challenges, a similar number of solutions and prospects are on the horizon. This review seeks to explore the changing trends and challenges in liver transplantation and highlight possible solutions and future directions.

Ex-Vivo Pharmacological Defatting of the Liver: A Review

The ongoing organ shortage has forced transplant teams to develop alternate sources of liver grafts. In this setting, ex-situ machine perfusion has rapidly developed as a promising tool to assess viability and improve the function of organs from extended criteria donors, including fatty liver grafts. In particular, normothermic machine perfusion represents a powerful tool to test a liver in full 37 °C metabolism and add pharmacological corrections whenever needed. In this context, many pharmacological agents and therapeutics have been tested to induce liver defatting on normothermic machine perfusion with promising results even on human organs. This systematic review makes a comprehensive synthesis on existing pharmacological therapies for liver defatting, with special focus on normothermic liver machine perfusion as an experimental ex-vivo translational model.

Defatting strategies in the current era of liver steatosis

Liver steatosis is emerging as a major cause of chronic liver disease worldwide, mainly due to the increasing rate of obesity, type 2 diabetes, and metabolic syndrome. Because of the increased incidence of liver steatosis, many organs are currently declined for transplantation despite high demand and waiting list mortality. Defatting strategies have recently emerged as a means of rapidly reducing liver steatosis to expand the pool of available organs. This review summarises advances in defatting strategies in experimental and human models of liver steatosis over the last 20 years.

Shorter Survival after Liver Pedicle Clamping in Patients Undergoing Liver Resection for Hepatocellular Carcinoma Revealed by a Systematic Review and Meta-Analysis

Simple Summary

Hepatocellular carcinoma (HCC) is the most prevalent tumor of the liver and represents the second most common cause of oncological-related deaths worldwide. Despite all progress made in the field, surgical resection or liver transplantation are, at the moment, the only curative therapies available. Liver resection, especially for large, central tumors, are at risk of important bleeding. Significative hemorrhage during HCC resections have been linked to an increased rate of post-operative complications and tumor recurrence. Therefore, hepatic pedicle clamping during surgery has been used in order to reduce the bleeding risks. However, this method induces ischemia/reperfusion injuries, which has also been associated with tumor recurrence. For this reason, we aimed to evaluate if pedicle clamping is indeed associated with tumor recurrence and shorter survival, by performing a systematic review of the literature and meta-analysis.

Abstract

Liver pedicle clamping minimizes surgical bleeding during hepatectomy. However, by inducing ischemia-reperfusion injury to the remnant liver, pedicle clamping may be associated with tumor recurrence in the regenerating liver. Hepatocellular carcinoma (HCC) having a high rate of recurrence, evidences demonstrating an eventual association with pedicle clamping is strongly needed. We did a systematic review of the literature until April 2020, looking at studies reporting the impact of liver pedicle clamping on long-term outcomes in patients undergoing liver resection for HCC. Primary and secondary outcomes were overall survival (OS) and disease-free survival, respectively. Results were obtained by random-effect meta-analysis and expressed as standardized mean difference (SMD). Eleven studies were included, accounting for 8087 patients. Results of seven studies were pooled in a meta-analysis. Findings indicated that, as compared to control patients who did not receive liver pedicle clamping, those who did had a significantly shorter OS (SMD = −0.172, 95%CI: −0.298 to −0.047, p = 0.007, I² = 76.8%) and higher tumor recurrence rates (odds ratio 1.36 1.01 to 1.83. p = 0.044, I² = 50.7%). This meta-analysis suggests that liver pedicle clamping may have a deleterious impact on long-term outcomes. An individual patient-data meta-analysis of randomized trials evaluating liver pedicle clamping is urgently needed.

Ex vivo machine perfusion: current applications and future directions in liver transplantation

BACKGROUND

Liver transplantation is the only curative treatment option for end-stage liver disease; however, its use remains limited due to a shortage of suitable organs. In recent years, ex vivo liver machine perfusion has been introduced to liver transplantation, as a means to expand the donor organ pool.

PURPOSE

To present a systematic review of prospective clinical studies on ex vivo liver machine perfusion, in order to assess current applications and highlight future directions.

METHODS

A systematic literature search of both PubMed and ISI web of science databases as well as the ClinicalTrials.gov registry was performed.

RESULTS

Twenty-one articles on prospective clinical trials on ex vivo liver machine perfusion were identified. Out of these, eight reported on hypothermic, eleven on normothermic, and two on sequential perfusion. These trials have demonstrated the safety and feasibility of ex vivo liver machine perfusion in both standard and expanded criteria donors. Currently, there are twelve studies enrolled in the clinicaltrials.gov  registry, and these focus on use of ex vivo perfusion in extended criteria donors and declined organs.

CONCLUSION

Ex vivo liver machine perfusion seems to be a suitable strategy to expand the donor pool for liver transplantation and holds promise as a platform for reconditioning diseased organs.

Cardiovascular involvement after liver transplantation: role of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis

Patients submitted to liver transplantation (LT) are exposed to high risk of cardiovascular (CV) complications which are the main determinants of both short-term and long-term morbidity and mortality in LT. Non-alcoholic fatty liver disease (NAFLD) is a very frequent condition in general population and is associated with a high risk of cardiovascular disease (CVD) which represents the first cause of death of these patients. NAFLD is predicted to become the first indication to LT and nowadays is also frequently detected in patients submitted to LT for other indications. Thus, the risk of CVD in patients submitted to LT is forecasted to increase in the next years. In this review the extent of CV involvement in patients submitted to LT and the role of NAFLD, either recurring after transplantation or as de novo presentation, in increasing CV risk is analysed. The risk of developing metabolic alterations, including diabetes, hypertension, dyslipidemia and weight gain, all manifestations of metabolic syndrome, occurring in the first months after LT, is depicted. The different presentations of cardiac involvement, represented by early atherosclerosis, coronary artery disease, heart failure and arrhythmias in patients with NAFLD submitted to LT is described. In addition, the tools to detect cardiac alterations either before or after LT is reported providing the possibility for an early diagnosis of CVD and an early therapy able to reduce morbidity and mortality for these diseases. The need for long-term concerted multidisciplinary activity with dietary counseling and exercise combined with drug treatment of all manifestations of metabolic syndrome is emphasized.

Sequential Protocol Biopsies Post-Liver Transplant From Donors With Moderate Macrosteatosis: What Happens to the Fat?

The number of steatotic deceased donor livers encountered has continued to rise as a result of the obesity epidemic. Little is known about the histological characteristics of moderately macrosteatotic livers over time in the recipient following liver transplantation (LT). All recipients undergoing LT at Mayo Clinic Florida with donor livers with moderate macrosteatosis (30%-60%) from 2000-2017 were identified (n = 96). Routine protocol liver biopsies were performed 1-week and 6-months following LT. All liver donor and protocol biopsies were read by an experienced liver pathologist. Of the 96 moderate macrosteatosis LTs, 70 recipients had post-LT protocol liver biopsies available and comprised the study cohort. Median donor allograft macrosteatosis at the time of transplant was 33% (IQR, 30%-40%) compared with 0% (IQR, 0%-2%) at 1-week (P < 0.001) and 0% (IQR, 0%-0%) at 6-months (P < 0.001) following LT. Biopsies at 1-week post-LT displayed pericentral necrosis in 57.1% of recipients and lipopeliosis in 34.3% of recipients. In the 6-month post-LT biopsies, cholestasis was seen in 3 (4.3%) of the recipients, whereas grade 2 fibrosis was seen in 6 recipients (8.6%). Graft survival at 5 years in the present cohort was 74.0%. Moderate macrosteatosis (30%-60%) in the donor allograft demonstrates complete reversal on liver biopsies performed as early as 7 days following LT and remains absent at 6-months following LT. Both pericentral necrosis and lipopeliosis are common features on day 7 biopsies. Despite these encouraging findings, the perioperative risks of using these livers (postreperfusion cardiac arrest and primary nonfunction) should not be understated. Long-term graft survival is acceptable in patients who are able to overcome the immediate perioperative risk of using moderately steatotic donor livers.

Clear mortality gap caused by graft macrosteatosis in Chinese patients after cadaveric liver transplantation

BACKGROUND

Liver transplantation (LT) is one of the most effective surgical treatment for patients with end-stage liver disease. Steatosis is a contributor for inferior graft quality. But its impact and safety on transplantation was less assessed in Chinese patients.

METHODS

Graft steatosis and related information involved in recipients, donors and surgical procedures were retrospectively collected from 239 patients.

RESULTS

Donor macrosteatosis (MaS) caused about 2.14 and 2.80 folds of increment on patient and graft mortality. Dose-response analysis revealed prominent risk of grafts on overall patient/organ mortality when MaS content exceeded 10% (P<0.05). Noteworthy, deaths were only observed in MaS group when concurrent with extremely higher post-transplant alanine aminotransferase (ALT, 64%). However, microsteatosis (MiS) grafts didn't affect outcomes after LT. In a cohort of Chinese patients, MaS had comprehensive effects on post-transplant outcomes with relatively lower safety threshold at 10%. Mortality gap caused by MaS grafts was observed in patients with severer ischemia reperfusion injury.

CONCLUSIONS

Our study revealled the graft MaS affected the post-transplant outcomes in lower risk cutoff in Chinese patients. Further study is worthy to validate these results and investigate inner mechanism under the phenomenon.

Differential Impact of Extended Criteria Donors After Brain Death or Circulatory Death in Adult Liver Transplantation

Using grafts from extended criteria donors (ECDs) and donation after circulatory death (DCD) donors is a strategy to address organ shortage in liver transplantation (LT). We studied the characteristics and outcomes of ECD and DCD grafts. We retrospectively studied consecutive adults who underwent deceased donor LT between 2006 and 2019. ECD was defined using modified Eurotransplant criteria. Our primary outcomes were graft and patient survival. A total of 798 grafts were used for LT, of which 93.1% were donation after brain death (DBD; 59.9% were also ECD) and 6.9% were DCD grafts (49.1% were also ECD). Among DBD graft recipients, donors having >33% liver steatosis or 3 ECD criteria resulted in poorer graft survival. Otherwise ECD graft recipients had similar graft and patient survival compared with non-ECD graft recipients. DCD graft recipients also had similar patient survival compared with DBD recipients. However, DCD grafts from an ECD appeared to have worse outcomes. DCD graft recipients experienced higher rates of early allograft dysfunction (50.9% versus 24.7%; P < 0.001) and ischemic biliopathy (16.4% versus 1.5%; P < 0.001) compared with DBD graft recipients. Use of DBD grafts from ECDs did not impact outcomes unless there was significant donor steatosis or 3 Eurotransplant criteria were met. DCD graft recipients have similar patient survival compared with DBD graft recipients as long as the donor was not an ECD. We recommend that DBD donors with 3 or more ECD features or >33% steatosis and DCD donors with any ECD features be used with caution in adult LT.

Update on liver transplantation-newer aspects

Liver transplantation (LT) remains the only therapeutic option offering gold standard treatment for end-stage liver disease (ESLD) and acute liver failure (ALF), as well as for certain early-stage liver tumors. Currently, the greatest challenge facing LT is the simple fact that there are not enough adequate livers for all the potential patients that could benefit from LT. Despite efforts to expand the donor pool to include living and deceased donors, organ shortage is still a major problem in many countries. To solve this problem, the use of marginal liver grafts has become an inevitable choice. Although the definition of marginal grafts or criteria for expanded donor selection has not been clarified yet, they are usually defined as grafts that may potentially cause primary nonfunction, impaired function, or late loss of function. These include steatotic livers, older donors, donors with positive viral serology, split livers, and donation after cardiac death (DCD). Therefore, to get the best outcome from these liver grafts, donor-recipient selection should be vigilant. Alcohol- related liver disease (ALD) is one of the most common indications for LT in Europe and North America. Traditionally, LT for alcoholic liver disease was kept limited for patients who have achieved 6 months of abstinence, in part due to social and ethical concerns regarding the use of a limited resource. However, the majority of patients with severe alcoholic hepatitis who fail medical therapy will not live long enough to meet this requirement. Besides, the initial results of early liver transplantation (ELT) without waiting for 6 months of abstinence period are satisfactory in severe alcoholic hepatitis (SAH). It will be important to take care of these patients from a newer perspective.

7-T MRI of explanted liver and ex-vivo pancreatic specimens: prospective study protocol of radiological-pathological correlation feasibility (the EXLIPSE project)

The study focuses on radiological-pathological correlation between imaging of ex vivo samples obtained by a 7-T scanner and histological examination. The specimens will be derived from native explanted cirrhotic livers, liver grafts excluded from donation because of severe steatosis, and primary pancreatic tumours. Magnetic resonance imaging (MRI) examinations will be performed within 24 h from liver or pancreatic lesion surgical removal. The MRI protocol will include morphological sequences, quantitative T1, T2, and fat-, water-fraction maps with Cartesian k-space acquisition, and multiparametric methods based on a transient-state “MRI fingerprinting”. Finally, the specimen will be fixed by formalin. Qualitative imaging analysis will be performed by two independent blinded radiologists to assess image consistency score. Quantitative analysis will be performed by drawing regions of interest on different tissue zones to measure T1 and T2 relaxation times as well as fat- and water-fraction. The same tissue areas will be analysed by the pathologists. This study will provide the possibility to improve our knowledge about qualitative and quantitative abdominal imaging assessment at 7 T, by correlating imaging characteristics and the corresponding histological composition of ex vivo specimens, in order to identify imaging biomarkers. Trial registration: ClinicalTrials.gov: 13646. Registered 9 July 2019—retrospectively registered

Use of Artificial Intelligence as an Innovative Method for Liver Graft Macrosteatosis Assessment

The worldwide implementation of a liver graft pool using marginal livers (ie, grafts with a high risk of technical complications and impaired function or with a risk of transmitting infection or malignancy to the recipient) has led to a growing interest in developing methods for accurate evaluation of graft quality. Liver steatosis is associated with a higher risk of primary nonfunction, early graft dysfunction, and poor graft survival rate. The present study aimed to analyze the value of artificial intelligence (AI) in the assessment of liver steatosis during procurement compared with liver biopsy evaluation. A total of 117 consecutive liver grafts from brain-dead donors were included and classified into 2 cohorts: ≥30 versus <30% hepatic steatosis. AI analysis required the presence of an intraoperative smartphone liver picture as well as a graft biopsy and donor data. First, a new algorithm arising from current visual recognition methods was developed, trained, and validated to obtain automatic liver graft segmentation from smartphone images. Second, a fully automated texture analysis and classification of the liver graft was performed by machine-learning algorithms. Automatic liver graft segmentation from smartphone images achieved an accuracy (Acc) of 98%, whereas the analysis of the liver graft features (cropped picture and donor data) showed an Acc of 89% in graft classification (≥30 versus <30%). This study demonstrates that AI has the potential to assess steatosis in a handy and noninvasive way to reliably identify potential nontransplantable liver grafts and to avoid improper graft utilization.

Deep learning quantification of percent steatosis in donor liver biopsy frozen sections

Background

Pathologist evaluation of donor liver biopsies provides information for accepting or discarding potential donor livers. Due to the urgent nature of the decision process, this is regularly performed using frozen sectioning at the time of biopsy. The percent steatosis in a donor liver biopsy correlates with transplant outcome, however there is significant inter- and intra-observer variability in quantifying steatosis, compounded by frozen section artifact. We hypothesized that a deep learning model could identify and quantify steatosis in donor liver biopsies.

Methods

We developed a deep learning convolutional neural network that generates a steatosis probability map from an input whole slide image (WSI) of a hematoxylin and eosin-stained frozen section, and subsequently calculates the percent steatosis. Ninety-six WSI of frozen donor liver sections from our transplant pathology service were annotated for steatosis and used to train (n = 30 WSI) and test (n = 66 WSI) the deep learning model.

Findings

The model had good correlation and agreement with the annotation in both the training set (r of 0.88, intraclass correlation coefficient [ICC] of 0.88) and novel input test sets (r = 0.85 and ICC=0.85). These measurements were superior to the estimates of the on-service pathologist at the time of initial evaluation (r = 0.52 and ICC=0.52 for the training set, and r = 0.74 and ICC=0.72 for the test set).

Interpretation

Use of this deep learning algorithm could be incorporated into routine pathology workflows for fast, accurate, and reproducible donor liver evaluation.

Funding

Mid-America Transplant Society

Metabonomic Profile of Macrosteatotic Allografts for Orthotopic Liver Transplantation in Patients With Initial Poor Function: Mechanistic Investigation and Prognostic Prediction

BACKGROUND

Our previous study revealled amplified hazardous effects of macrosteatosis (MaS) on graft failure (GF) in recipients with severe liver damage in short post-operative days, with vague mechanism inside.

AIM

We aimed to uncover the molecular mechanism of donor MaS on GF, and construct the predictive model to monitor post-transplant prognosis based on "omics" perspective.

METHODS

Ultra-performance liquid chromatography coupled to mass spectrometry metabolomic analysis was performed in allograft tissues from 82 patients with initial poor function (IPF) from multi-liver transplant (LT) centers. Pathway analysis was performed by on-line toolkit Metaboanalyst (v 3.0). Predictive model was constructed based on combinative metabonomic and clinical data extracted by stepwised cox proportional analysis.

RESULTS

Principle component analysis (PCA) analysis revealled stratification on metabolic feature in organs classified by MaS status. Differential metabolits both associated with MaS and GF were significantly enriched on pathway of glycerophospholipid metabolism (P < 0.05). Phosphatidylcholine (PC) and phosphatidylethanolamine (PE) involved in glycerophospholipid metabolism was significantly decreased in cases with MaS donors and GF (P < 0.05). Better prediction was observed on graft survival by combinative model (area under the curve = 0.91) and confirmed by internal validation.

CONCLUSION

Metabonomic features of allografts can be clearly distinguished by MaS status in patients with IPF. Dysfunction on glycerophospholipid metabolism was culprit to link donor MaS and final GF. Decrement on PC and PE exerted the fatal effects of MaS on organ failure. Metabonomic data might help for monitoring long-term graft survival after LT.

Outcomes After Declining a Steatotic Donor Liver for Liver Transplant Candidates in the United States

BACKGROUND

Steatotic donor livers (SDLs, ≥30% macrosteatosis on biopsy) are often declined, as they are associated with a higher risk of graft loss, even though candidates may wait an indefinite time for a subsequent organ offer. We sought to quantify outcomes for transplant candidates who declined or accepted an SDL offer.

METHODS

We used Scientific Registry of Transplant Recipients offer data from 2009 to 2015 to compare outcomes of 759 candidates who accepted an SDL to 13 362 matched controls who declined and followed candidates from the date of decision (decline or accept) until death or end of study period. We used a competing risk framework to understand the natural history of candidates who declined and Cox regression to compare postdecision survival after declining versus accepting (ie, what could have happened if candidates who declined had instead accepted).

RESULTS

Among those who declined an SDL, only 53.1% of candidates were subsequently transplanted, 23.8% died, and 19.4% were removed from the waitlist. Candidates who accepted had a brief perioperative risk period within the first month posttransplant (adjusted hazard ratio [aHR]: 2.493.494.89, P < 0.001), but a 62% lower mortality risk (aHR: 0.310.380.46, P < 0.001) beyond this. Although the long-term survival benefit of acceptance did not vary by candidate model for end-stage liver disease (MELD), the short-term risk period did. MELD 6-21 candidates who accepted an SDL had a 7.88-fold higher mortality risk (aHR: 4.807.8812.93, P < 0.001) in the first month posttransplant, whereas MELD 35-40 candidates had a 68% lower mortality risk (aHR: 0.110.320.90, P = 0.03).

CONCLUSIONS

Appropriately selected SDLs can decrease wait time and provide substantial long-term survival benefit for liver transplant candidates.

Minimizing Risks of Liver Transplantation With Steatotic Donor Livers by Preferred Recipient Matching

BACKGROUND

Donor livers with ≥30% macrosteatosis (steatotic livers) represent a possible expansion to the donor pool, but are frequently discarded as they are associated with an increased risk of mortality and graft loss. We hypothesized that there are certain recipient phenotypes that would tolerate donor steatosis well, and are therefore best suited to receive these grafts.

METHODS

Using national registry data from the Scientific Registry of Transplant Recipients between 2006 and 2017, we compared 2048 liver transplant recipients of steatotic livers with 69 394 recipients of nonsteatotic (<30%) livers. We identified recipient factors that amplified the impact of donor steatosis on mortality and graft loss using interaction analysis, classifying recipients without these factors as preferred recipients. We compared mortality and graft loss with steatotic versus nonsteatotic livers in preferred and nonpreferred recipients using Cox regression.

RESULTS

Preferred recipients of steatotic livers were determined to be first-time recipients with a model for end-stage liver disease 15-34, without primary biliary cirrhosis, and not on life support before transplant. Preferred recipients had no increased mortality risk (hazard ratio [HR]: 0.921.041.16; P = 0.5) or graft loss (HR: 0.931.031.15; P = 0.5) with steatotic versus nonsteatotic livers. Conversely, nonpreferred recipients had a 41% increased mortality risk (HR: 1.171.411.70; P < 0.001) and 39% increased risk of graft loss (HR: 1.161.391.66; P < 0.001) with steatotic versus nonsteatotic livers.

CONCLUSIONS

The risks of liver transplantation with steatotic donor livers could be minimized by appropriate recipient matching.

Early Allograft Dysfunction Following Liver Transplant: Impact of Obesity, Diabetes, and Red Blood Cell Transfusion

PURPOSE

We examined the role of obesity and intraoperative red blood cell (RBC) and platelet transfusion in early allograft dysfunction (EAD) following liver transplantation (LT).

METHODS

This is a retrospective analysis of 239 adult deceased-donor LT recipients over a 10-year period. EAD was defined by Olthoff's criteria. Data collection included donor (D) and recipient (R) age, body mass index (BMI) ≥ 35 kg/m², diabetes mellitus, allograft macrosteatosis, and intraoperative (RBC) and platelet administration. We employed logistic regression to evaluate associations of these factors with EAD. Results are presented as odds ratios (OR) and 95% confidence intervals (CI) with corresponding P values. A P ≤ .05 was considered statistically significant.

RESULTS

EAD occurred in 85 recipients (36%). Macrosteatosis data were available for 199 donors. In the multivariate analyses, BMI-D ≥ 35 kg/m² increased the odds of developing EAD by 156% in the entire cohort (OR 2.56, 95% CI 1.09-6.01) and by 187% in recipients with macrosteatosis data (n = 199, OR 2.87, 95% CI 1.15-7.15). Each unit of RBCs increased the odds for EAD by 8% (OR 1.08, 95% CI 1.02-1.14) and, for the subgroup of 238 recipients with macrosteatosis data, by 9% (OR 1.09, 95% CI 1.02-1.16).

CONCLUSION

We found a significant independent association of donor obesity and intraoperative RBC transfusion with EAD but no such association for platelet administration, MELD score, age, recipient obesity, and diabetes.

NAFLD Epidemiology, Emerging Pharmacotherapy, Liver Transplantation Implications and the Trends in the United States

Nonalcoholic fatty liver disease (NAFLD) is a hepatic manifestation of metabolic syndrome. The spread of obesity worldwide in pandemic proportions has led to a rapid rise of NAFLD in developed and developing countries alike. There are no approved pharmacological agents to treat steatohepatitis or advanced fibrosis but obeticholic acid recently has shown some promise in phase III trial. Currently, NAFLD is the number one etiology for simultaneous liver and kidney transplantation in the USA, second most common indication for liver transplantation (LT) and projected to become number one very soon. LT for NAFLD poses unique challenges, as these patients are generally older, obese and more likely to have a number of metabolic risk factors. Bariatric surgery is an option and can be considered if a structured weight loss program does not achieve the sustained weight loss goal. Comprehensive cardiovascular risk assessment and aggressive management of comorbid conditions are crucial in the LT evaluation process to improve post-transplant survival. Recurrent nonalcoholic steatohepatitis after LT is not uncommon, and thus warrants primary and secondary prevention strategies through a multidisciplinary approach. Prevalence of NAFLD in a donor population is a unique and growing concern that limits the access to quality liver grafts.

Links between donor macrosteatosis, interleukin-33 and complement after liver transplantation

BACKGROUND

As prevalence of nonalcoholic fatty liver disease increases in the population, livers with steatosis will continue to infiltrate the donor pool. Safe utilization of these extended criteria grafts is paramount given the increased risk associated with their use in transplantation. Prognostic factors that can predict liver dysfunction immediately after transplantation with macrosteatotic grafts are lacking.

AIM

To understand the relationship between interleukin-33 (IL-33) and complement in recipients immediately following liver reperfusion as a marker of liver dysfunction.

METHODS

Cohort consisted of patients who received a liver transplant from September 2016–September 2019 at our institution. Clinical variables were retrospectively extracted from the electronic medical record. Back-table donor biopsies were obtained with donor steatosis percentage retrospectively determined by a board-certified pathologist. Blood samples were available immediately following liver transplantation. Quantification of plasma IL-33 and complement proteins, C3a and C5a, were determined by enzyme-linked immunosorbent assay. For mRNA expression, RNA was extracted from donor biopsies and used against a 780 gene panel.

RESULTS

Cohort consisted of 99 donor and recipients. Donor median age was 45 years and 55% male. Recipients had a median age of 59 years with 62% male. The main etiologies were alcoholic hepatitis, nonalcoholic steatohepatitis, and hepatocellular carcinoma. Median MELD-Na at transplant was 21. Donors were grouped based on moderate macrosteatosis (≥ 30%). Recipients implanted with moderate macrosteatotic grafts had significantly higher peak alanine aminotransferase/aspartate aminotransferase (P < 0.001 and P < 0.004), and increased incidence of early allograft dysfunction (60% compared to 18%). Circulating IL-33 levels were significantly elevated in recipients of ≥ 30% macrosteatotic grafts (P < 0.05). Recipients with detectable levels of circulating IL-33 immediately following reperfusion had significantly higher alanine aminotransferase/aspartate aminotransferase (P < 0.05 and P < 0.01). Activated complement (C3a and C5a) were elevated in recipients implanted with moderate macrosteatotic grafts. RNA expression analysis of donor biopsies revealed moderate steatotic grafts upregulated genes inflammatory processes while downregulated hepatocyte-produced complement factors.

CONCLUSION

Circulating IL-33 and activated complement levels immediately following liver reperfusion in recipients of moderate macrosteatotic grafts may identify which patients are at risk of early allograft dysfunction.

Fully automated quantitative assessment of hepatic steatosis in liver transplants

BACKGROUND

The presence of macro- and microvesicular steatosis is one of the major risk factors for liver transplantation. An accurate assessment of the steatosis percentage is crucial for determining liver graft transplantability, which is currently based on the pathologists' visual evaluations on liver histology specimens.

METHOD

The aim of this study was to develop and validate a fully automated algorithm, called HEPASS (HEPatic Adaptive Steatosis Segmentation), for both micro- and macro-steatosis detection in digital liver histological images. The proposed method employs a hybrid deep learning framework, combining the accuracy of an adaptive threshold with the semantic segmentation of a deep convolutional neural network. Starting from all white regions, the HEPASS algorithm was able to detect lipid droplets and classify them into micro- or macrosteatosis.

RESULTS

The proposed method was developed and tested on 385 hematoxylin and eosin (H&E) stained images coming from 77 liver donors. Automated results were compared with manual annotations and nine state-of-the-art techniques designed for steatosis segmentation. In the TEST set, the algorithm was characterized by 97.27% accuracy in steatosis quantification (average error 1.07%, maximum average error 5.62%) and outperformed all the compared methods.

CONCLUSIONS

To the best of our knowledge, the proposed algorithm is the first fully automated algorithm for the assessment of both micro- and macrosteatosis in H&E stained liver tissue images. Being very fast (average computational time 0.72 s), this algorithm paves the way for automated, quantitative and real-time liver graft assessments.

Use of machine perfusion in livers showing steatosis prior to transplantation: a systematic review

BACKGROUND

The role of machine perfusion (MP) in the evaluation of liver grafts with macrovesicular steatosis (MaS) remains ill-defined as only a limited number of studies has been reported. The objective of the current study was to provide a systematic review to evaluate the role of MP in the setting of MaS livers.

METHODS

A systematic review, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was performed. Eligible articles published up to April 2019 were included using the MEDLINE, Scopus, and Google Scholar databases.

RESULTS

Among the 422 articles screened, only 16 papers met the inclusion criteria. A total of 54 cases of MP use before liver transplantation were included. Sixteen (29.6%) grafts were from donors after circulatory death. In 22 (40.7%) cases, hypothermic machine perfusion was performed. Normothermic machine perfusion was done in the remaining 32 (59.3%) cases. According to the histological results of the donor core biopsy, a MaS value < 30% was observed in 41 (75.9%) cases, whereas 13 (24.1%) patients had moderate-to-severe (≥ 30%) MaS. Following categorization of the pooled population according to the presence of moderate-to-severe (≥ 30%) MaS in the donor graft, no differences were noted in terms of post-transplant death or severe complications following MP. There was no correlation between the proportion of MaS in the donor graft relative to post-transplant peak ALT among patients treated with MP. Among the entire pooled cohort, there was also no correlation between MaS values and ALT peak (R = 0.13; P = 0.42).

CONCLUSIONS

MP appears to be feasible and safe in MaS livers. Experience to date has been very limited, and the benefit of MP remains not determined. Prospective studies will need to define better the potential effect of "defatting" drugs used during the perfusion process on MaS.