Use of severely steatotic grafts in liver transplantation: a matched case-control study

Early living donor liver transplantation for alcohol-associated hepatitis: Status in the era of increasing demand, unmet needs, and future considerations

Hazardous alcohol consumption is the leading cause of liver disease worldwide. Alcohol-associated hepatitis (AH) is an acute and serious presentation of alcohol-associated liver disease that is associated with high short-term mortality. Medical management remains limited to corticosteroid therapy and intensive nutrition but improves survival in <50% of individuals. Liver transplantation (LT) is increasingly recognized as a treatment option for many patients with AH and may lead to greater survival benefits than medical management alone. The rate of waitlistings and LTs for AH has doubled in recent years, especially in the United States. Several studies from the West have reported early LT for AH to be successful, where deceased donor LT is the norm. The challenges of LT in living donor centers, particularly for those with AH, are unique and have previously not been discussed in depth. In this review, we aim to discuss the challenges unique to LDLT with respect to candidate and donor selection, ethical considerations, disparities in LDLT, post-LT alcohol relapse, and measures to prevent them while also addressing the definitions and outcomes of early-living donor liver LT for AH.

Comprehensive Evaluation of Human Donor Liver Viability with Polarization-Sensitive Optical Coherence Tomography

Human liver transplantation is severely constrained by a critical shortage of donor livers, with approximately one quarter of patients on the waiting list dying due to the scarcity of viable organs. Current liver viability assessments, which rely on invasive pathological methods, are hampered by limited sampling from biopsies, particularly in marginal livers from extended criteria donors (ECD) intended to expand the donor pool. Consequently, there is a pressing need for more comprehensive and non-invasive evaluation techniques to meet the escalating demand for liver transplants. In this study, we propose the use of polarization-sensitive optical coherence tomography (PS-OCT) to perform a thorough viability evaluation across the entire surface of donor livers. PS-OCT imaging was conducted on multiple regions, achieving near-complete coverage of the liver surface, and the findings were cross-validated with histopathological evaluations. The analysis of hepatic parameters derived from pathology highlighted tissue heterogeneity. Leveraging machine learning and texture analysis, we quantified hepatic steatosis, fibrosis, inflammation, and necrosis, and established strong correlations (≥ 80%) between PS-OCT quantifications and pathological assessments. PS-OCT offers a non-invasive assessment of liver viability by quantifying hepatic parenchymal parameters across the entire donor liver, significantly complementing current pathological analysis. These results suggest that PS-OCT provides a robust, non-invasive approach to assessing donor liver viability, which could potentially decrease the discard rate of higher risk livers, thereby expanding the donor pool and reducing the inadvertent use of those livers unsuitable for transplantation.

Development and validation of a model for early survival prediction following liver transplantation based on donor and recipient characteristics

BACKGROUND

Circulating cytokine levels not only correlate with the progression of liver disease but also serve as indicators for the infection status of the body. Growing evidence points to the connection between donor cytokines and graft function following transplantation. This study set out to explore the clinical significance of donor cytokines in predicting liver transplantation prognosis.

METHODS

Data from 172 deceased donor liver transplantations conducted between 2017 and 2022, with available donor serum cytokine information, were collected. The subjects were randomly divided into estimation (n = 120) and validation (n = 52) groups to establish and validate the model. The newly developed SA10 score was compared against established models EAD, MEAF, L-GrAFT7, and L-GrAFT10.

RESULTS

Donor IL-10, along with donor age and recipient AST peak value within the first 7 days post-operation, was identified as an independent factor associated with recipient survival and was incorporated into the SA10 score. SA10 exhibited robust predictive capability, particularly for 1-month survival (AUC = 0.90, 95% CI = 0.84-0.96), outperforming EAD (AUC = 0.75, 95% CI = 0.60-0.90, p = 0.04) and L-GrAFT7 (AUC = 0.65, 95% CI = 0.49-0.81, p < 0.01). Comparable performance was observed between SA10, MEAF, and L-GrAFT10.

CONCLUSION

Donor IL-10 independently influences recipient survival, with the SA10 score demonstrating comparable and even superior predictive ability compared to existing models.

Overweight Impacts Histological Disease Activity of De Novo Metabolic Dysfunction-Associated Steatotic Liver Disease After Liver Transplantation

BACKGROUND AND AIMS

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a leading indication for liver transplantation (LT), but also occurs after LT. The prevalence of de novo MASLD (dnMASLD) after LT, based on both surveillance (svLbx) and indication biopsies (indLbx), is unknown. Furthermore, the impact of the distinct cardiometabolic risk factors on histological disease activity has not been assessed. We aimed to evaluate the prevalence of dnMASLD and the association between the cardiometabolic risk factors and histological disease activity.

METHODS

We performed a retrospective single-center study in a LT cohort with indLbx and svLbx. Patients with NAFLD before LT were excluded.

RESULTS

We analyzed 249 patients who underwent either svLbx or indLbx. Forty-eight (19.2%) had either dnMASLD (n = 26/249, 10.4%) or metabolic dysfunction associated steatohepatitis (dnMASH) (n = 22/249, 8.8%). Although dnMASLD/dnMASH was more frequent in indLbx (35.1%, p < 0.01), still 16.5% of patients with svLbx had dnMASLD/dnMASH. While overweight (p < 0.01) and diabetes (p = 0.01) were more frequent in patients with dnMASH, only overweight was associated with histological disease activity in the multivariate analysis. No impact of dnMASLD on the overall survival was observed.

CONCLUSION

While dnMASLD is more frequent in patients with indLBX, it also occurs in 16.5% of patients without signs of graft dysfunction. Overweight has the strongest impact on histological disease activity and should be monitored carefully after LT.

Comparing Different Methods for the Diagnosis of Liver Steatosis: What Are the Best Diagnostic Tools?

BACKGROUND

Due to the ongoing organ shortage, marginal grafts with steatosis are more frequently used in liver transplantation, leading to higher occurrences of graft dysfunction. A histological analysis is the gold standard for the quantification of liver steatosis (LS), but has its drawbacks: it is an invasive method that varies from one pathologist to another and is not available in every hospital at the time of organ procurement. This study aimed to compare non-invasive diagnostic tools to a histological analysis for the quantification of liver steatosis.

METHODS

Male C57BL6J mice were fed with a methioninecholine-deficient (MCD) diet for 14 days or 28 days to induce LS, and were compared to a control group of animals fed with a normal diet. The following non-invasive techniques were performed and compared to the histological quantification of liver steatosis: magnetic resonance spectroscopy (MRS), CARS microscopy, 99mTc MIBI SPECT imaging, and a new near-infrared spectrometer (NIR-SG1).

RESULTS

After 28 days on the MCD diet, an evaluation of LS showed ≥30% macrovesicular steatosis. High correlations were found between the NIR-SG1 and the blinded pathologist analysis (R2 = 0.945) (p = 0.001), and between the CARS microscopy (R2 = 0.801 (p < 0.001); MRS, R2 = 0.898 (p < 0.001)) and the blinded pathologist analysis. The ROC curve analysis showed that the area under the curve (AUC) was 1 for both the NIR-SG1 and MRS (p = 0.021 and p < 0.001, respectively), while the AUC = 0.910 for the Oil Red O stain (p < 0.001) and the AUC = 0.865 for the CARS microscopy (p < 0.001). The AUC for the 99mTc MIBI SPECT was 0.640 (p = 0.013), and this was a less discriminating technique for LS quantification.

CONCLUSIONS

The best-performing non-invasive methods for LS quantification are MRS, CARS microscopy, and the NIR-SG1. The NIR-SG1 is particularly appropriate for clinical practice and needs to be validated by clinical studies on liver grafts.

Clinical Application of Infrared Spectroscopy in Liver Transplantation for Rapid Assessment of Lipid Content in Liver Graft

Liver transplantation (LT) is a major treatment for patients with end-stage liver diseases. Steatosis is a significant risk factor for primary graft nonfunction and associated with poor long-term graft outcomes. Traditionally, the evaluation of steatosis is based on frozen section examination to estimate the percentage of hepatocytes containing lipid vesicles. However, this visual evaluation correlates poorly with the true lipid content. This study aimed to address the potential of infrared (IR) microspectroscopy for rapidly estimating lipid content in the context of LT and assessing its impact on survival. Clinical data were collected for >20 months from 58 patients who underwent transplantation. For each liver graft, macrovacuolar steatosis and microvesicular steatosis were evaluated through histologic examination of frozen tissue section. Triglycerides (TG) were further quantified using gas phase chromatography coupled with a flame ionization detector (GC-FID) and estimated by IR microspectroscopy. A linear relationship and significant correlation were observed between the TG measured by GC-FID and those estimated using IR microspectroscopy (R2 = 0.86). In some cases, microvesicular steatosis was related to high lipid content despite low levels of macrovacuolar steatosis. Seven patients experienced posttransplantation liver failure, including 5 deceased patients. All patients underwent transplantation with grafts containing significantly high TG levels. A concentration of 250 nmol/mg was identified as the threshold above which the risk of failure after LT significantly increased, affecting 35% of patients. Our study established a strong correlation between LT outcomes and lipid content. IR microspectroscopy proved to be a rapid and reliable approach for assessing the lipid content in clinical settings.

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.

Assessment of large droplet fat in frozen sections of donor liver biopsies: utility and interobserver variability of the newly described Banff method compared to a simplified Average of Fields method

AIMS

There is great variability in the assessment and reporting of fat in frozen sections of donor liver biopsies. The Banff Working Group has proposed a novel method and definition for scoring large droplet fat (LDF) in donor liver biopsies. This study compares the Banff method with a simpler Average of Fields (AF) method and evaluates the impact of different LDF definitions.

METHODS

Three pathologists assessed percentage of LDF (LDF%) in 10 donor liver biopsies using Banff and AF methods, applying the Banff LDF definition (cell distention with a single droplet larger than adjacent hepatocytes). Additionally, LDF% by the AF method was compared using two LDF definitions: Banff definition versus LDF definition 2 (single fat droplet occupying greater than half of a hepatocyte with nuclear displacement).

RESULTS

Intraobserver concordance between the Banff and AF methods was similar for all three pathologists (kappa 0.76-1). Both methods exhibited 70% interobserver concordance, and there was substantial agreement (kappa 0.68) in the LDF% among the three pathologists for both methods. Comparing the two LDF definitions, results were significantly lower with the Banff definition; LDF >50% was observed in four cases with LDF definition 2 but none of the cases with the Banff definition.

CONCLUSIONS

There is high interobserver and intraobserver concordance of LDF% between the Banff and AF methods. LDF% determined by the Banff definition was lower than with LDF definition 2, and needs to be validated based on graft outcome before it can be recommended for clinical use.

Exploring the effects of epigallocatechin gallate on lipid metabolism in the rat steatotic liver during normothermic machine perfusion: Insights from lipidomics and RNA sequencing

BACKGROUND

Hepatic steatosis is the leading cause of discarded liver grafts. Defatting steatotic liver grafts using drug combinations during ex vivo normothermic machine perfusion (NMP) has been reported. However, the effectiveness of NMP in reducing fat content using epigallocatechin gallate (EGCG) as a single defatting agent and its effect on lipid metabolism are poorly investigated.

METHODS

In this study, an NMP system was set up to perfuse a steatotic liver from a rat model with 10 mM EGCG. Livers without EGCG served as NMP controls, whereas static cold-preserved livers in the University of Wisconsin medium were used as static cold storage controls. Liver enzyme, reactive oxygen species (ROS), histology, and lipid content assessments were conducted post-perfusion, complemented by lipidomics, RNA sequencing, and western blotting to determine the lipid metabolism changes.

RESULTS

EGCG during NMP reduced hepatocellular injury markers and defatted steatotic liver grafts. Additionally, we observed a significant increase in triglyceride (TG) content in the perfusate post-NMP in the NMP + EGCG group, suggesting TG output from the liver. Furthermore, lipidomics analysis revealed that EGCG primarily affected metabolites involved in glycerophospholipid (GP) and glycerolipid (GL) metabolism. Further, the RNA sequencing indicated the modulation of these metabolic pathways via ECGC, which was associated with the downregulated Lpin1 and Gpat3 expression.

CONCLUSIONS

EGCG defats steatotic livers as a single defatting agent during NMP by promoting GL and GP metabolism via decreasing Lpin1 and Agpat9 levels.

Fluorescence confocal microscopy on liver specimens for full digitization of transplant pathology

Fluorescence confocal microscopy (FCM) is a rapidly evolving tool that provides real-time virtual HE images of native tissue. Data about the potential of FCM as an alternative to frozen sections for the evaluation of donor liver specimens are lacking so far. The aim of the current study was to determine the value of FCM in liver specimens according to the criteria of the German Society for Organ Procurement. In this prospective study, conventional histology and FCM scans of 50 liver specimens (60% liver biopsies, 26% surgical specimens, and 14% donor samples) were evaluated according to the German Society for Organ Procurement. A comparison of FCM scans and conventional frozen sections revealed almost perfect levels of agreement for cholangitis (κ = 0.877), fibrosis (κ = 0.843), and malignancy (κ = 0.815). Substantial levels of agreement could be obtained for macrovesicular steatosis (κ = 0.775), inflammation (κ = 0.763), necrosis (κ = 0.643), and steatohepatitis (κ = 0.643). Levels of agreement were moderate for microvesicular steatosis (κ = 0.563). The strength of agreement between frozen sections and FCM was superior to the comparison of conventional HE and FCM imaging. We introduce FCM as a potential alternative to the frozen section that may represent a novel approach to liver transplant pathology where timely feedback is crucial and the deployment of human resources is becoming increasingly difficult.

Development of a portable device to quantify hepatic steatosis in potential donor livers

An accurate estimation of liver fat content is necessary to predict how a donated liver will function after transplantation. Currently, a pathologist needs to be available at all hours of the day, even at remote hospitals, when an organ donor is procured. Even among expert pathologists, the estimation of liver fat content is operator-dependent. Here we describe the development of a low-cost, end-to-end artificial intelligence platform to evaluate liver fat content on a donor liver biopsy slide in real-time. The hardware includes a high-resolution camera, display, and GPU to acquire and process donor liver biopsy slides. A deep learning model was trained to label and quantify fat globules in liver tissue. The algorithm was deployed on the device to enable real-time quantification and characterization of fat content for transplant decision-making. This information is displayed on the device and can also be sent to a cloud platform for further analysis.

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.

A Review of Machine Perfusion Strategies in Liver Transplantation

The acceptance of liver transplantation as the standard of care for end-stage liver diseases has led to a critical shortage of donor allografts. To expand the donor organ pool, many countries have liberalized the donor criteria including extended criteria donors and donation after circulatory death. These marginal livers are at a higher risk of injury when they are preserved using the standard static cold storage (SCS) preservation techniques. In recent years, research has focused on optimizing organ preservation techniques to protect these marginal livers. Machine perfusion (MP) of the expanded donor liver has witnessed considerable advancements in the last decade. Research has showed MP strategies to confer significant advantages over the SCS techniques, such as longer preservation times, viability assessment and the potential to recondition high risk allografts prior to implantation. In this review article, we address the topic of MP in liver allograft preservation, with emphasis on current trends in clinical application. We discuss the relevant clinical trials related to the techniques of hypothermic MP, normothermic MP, hypothermic oxygenated MP, and controlled oxygenated rewarming. We also discuss the potential applications of ex vivo therapeutics which may be relevant in the future to further optimize the allograft prior to transplantation.

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.

The Impact of CT-Assessed Liver Steatosis on Postoperative Complications After Pancreaticoduodenectomy for Cancer

INTRODUCTION

Liver steatosis (LS) has been increasingly described in preoperative imaging of patients undergoing pancreaticoduodenectomy (PD). The aim of this study was to assess the impact of preoperative LS on complications after PD and identify possible contributors to LS development in this specific cohort.

METHODS

Pancreatic head adenocarcinoma (PDAC) patients scheduled for PD, with preoperative CT-imaging available were included in the study. LS was defined as mean liver density lower than 45 Hounsfield units. Patients showing preoperative LS were matched for patient age, gender, BMI, ASA score, neoadjuvant treatment, and vascular and multivisceral resections, based on propensity scores in a 1:2 ratio to patients with no LS. The primary outcome was postoperative complication severity at 90 days as measured by the comprehensive complication index (CCI) RESULTS: Overall, 247 patients were included in the study. Forty-three (17%) patients presented with LS at preoperative CT-scan. After matching, the LS group included 37 patients, whereas the non-LS group had 74 patients. LS patients had a higher mean (SD) CCI, 29.7 (24.5) versus 19.5 (22.5), p = 0.035, and a longer length of hospital stay, median [IQR] 12 [8-26] versus 8 [7-13] days, p = 0.006 compared with non-LS patients. On multivariate analysis, variables independently associated with CCI were: LS (16% increase, p = 0.048), male sex (19% increase, p = 0.030), ASA score ≥ 3 (26% increase, p = 0.002), fistula risk score (FRS) (28% increase for each point of FRS, p = 0.001) and vascular resection (20% increase, p = 0.019).

CONCLUSION

Preliminary evidence suggests that preoperative LS assessed by CT-scan influences complication severity in patients undergoing PD for PDAC.

A Novel Digital Algorithm for Identifying Liver Steatosis Using Smartphone-Captured Images

Access to lifesaving liver transplantation is limited by a severe organ shortage. One factor contributing to the shortage is the high rate of discard in livers with histologic steatosis. Livers with <30% macrosteatosis are generally considered safe for transplant. However, histologic assessment of steatosis by a pathologist remains subjective and is often limited by image quality. Here, we address this bottleneck by creating an automated digital algorithm for calculating histologic steatosis using only images of liver biopsy histology obtained with a smartphone.

Identification and Isolation of Type II NKT Cell Subsets in Human Blood and Liver

Background

Steatotic livers are more prone to rejection, but are often transplanted owing to the shortage of available organs. Type II NKT (T2NKT) cells are liver-resident lymphocytes that react to lipids presented by CD1d. The role of T2NKT cells in rejection of fatty liver transplants is unclear, partly because of a lack of T2NKT cell markers and their very low frequency in blood. Here, we quantify human T2NKT cells in blood and liver tissue by flow cytometry and provide a strategy for their enrichment and expansion.

Methods

Human T2NKT cells were identified as CD3⁺ CD56⁺ CD161⁺ TCR-γᵹ^- TCRVα7.2^- and TCRVα24^- cells. T2NKT cells were enriched from blood by sequential positive selection using CD56 and CD3 microbeads. These were subsequently FACS-sorted to purity then expanded in vitro for 3 weeks using anti-CD3/CD28 beads and TGF-β1.

Results

The frequency of human T2NKT cells in blood was very low (0.8 ± 0.4% of CD3⁺ T cells) but they were a more abundant population in liver (6.3 ± 0.9%). Enriched T2NKT cells expressed the transcription factor PLZF. A novel subset of FoxP3⁺ T2NKT cells was discovered in blood and liver tissue. T2NKT cells were expanded in culture by 15- to 28-fold over 3 weeks, during which time they maintained expression of all identifying markers, including PLZF and FoxP3.

Conclusions

Our work defines new strategies for identifying and isolating T2NKT cells from human blood and liver tissue. We showed that this rare population can be expanded in vitro in order to obtain experimentally amenable cell numbers. Further, we identified a novel T2NKT cell subset that stably expresses FoxP3, which might play a role in regulating innate-like lymphocyte responses in steatotic liver transplants.

Artificial intelligence for prediction of donor liver allograft steatosis and early post-transplantation graft failure

BACKGROUND

Donor livers undergo subjective pathologist review of steatosis before transplantation to mitigate the risk for early allograft dysfunction (EAD). We developed an objective, computer vision artificial intelligence (CVAI) platform to score donor liver steatosis and compared its capability for predicting EAD against pathologist steatosis scores.

METHODS

Two pathologists scored digitized donor liver biopsy slides from 2014 to 2019. We trained four CVAI platforms with 1:99 training:prediction split. Mean intersection-over-union (IU) characterized CVAI model accuracy. We defined EAD using liver function tests within 1 week of transplantation. We calculated separate EAD logistic regression models with CVAI and pathologist steatosis and compared the models' discrimination and internal calibration.

RESULTS

From 90 liver biopsies, 25,494 images trained CVAI models yielding peak mean IU = 0.80. CVAI steatosis scores were lower than pathologist scores (median 3% vs 20%, P < 0.001). Among 41 transplanted grafts, 46% developed EAD. The median CVAI steatosis score was higher for those with EAD (2.9% vs 1.9%, P = 0.02). CVAI steatosis was independently associated with EAD after adjusting for donor age, donor diabetes, and MELD score (aOR = 1.34, 95%CI = 1.03-1.75, P = 0.03).

CONCLUSION

The CVAI steatosis EAD model demonstrated slightly better calibration than pathologist steatosis, meriting further investigation into which modality most accurately and reliably predicts post-transplantation outcomes.

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.

A Novel Multidrug Combination Mitigates Rat Liver Steatosis Through Activating AMPK Pathway During Normothermic Machine Perfusion

BACKGROUND

Hepatic steatosis is now the leading cause of liver discards in deceased donors. Previous studies [Yarmush formula (Y) defatting] have successfully reduced the fat content by treating rat steatotic livers on extracorporeal normothermic machine perfusion (NMP) with a multidrug combination including the GW compounds that were linked to an increased risk of carcinogenesis.

METHODS

We developed a novel multidrug combination by replacing the GW compounds with 2 polyphenols, epigallocatechin-3-gallate (E) and resveratrol (R). Sixteen rat livers were placed on NMP and assigned to control, Y defatting, Y + E + R defatting, or Y'-GW + E + R defatting groups (Y'-GW = 90% dose-reduced Y defatting, n = 4/group).

RESULTS

All livers in defatting groups had significant decreases in hepatic triglyceride content at the end of the experiment. However, livers treated with our novel Y'-GW + E + R combination had evidence of increased metabolism and less hepatocyte damage and carcinogenic potential. Our Y'-GW + E + R combination had increased phosphorylation of AMP-activated protein kinase (P = 0.019) and acetyl-CoA carboxylase (P = 0.023) compared with control; these were not increased in Y + E + R group and actually decreased in the Y group. Furthermore, the Y'-GW + E + R group had less evidence of carcinogenic potential with no increase in AKT phosphorylation compared with control (P = 0.089); the Y (P = 0.031) and Y + E + R (P = 0.035) groups had striking increases in AKT phosphorylation. Finally, our Y'-GW + E + R showed less evidence of hepatocyte damage with significantly lower perfusate alanine aminotransferase (P = 0.007) and aspartate aminotransferase (P = 0.014) levels.

CONCLUSIONS

We have developed a novel multidrug combination demonstrating promising defatting efficacy via activation of the AMP-activated protein kinase pathway with an optimized safety profile and reduced hepatotoxicity during ex vivo NMP.

Ischemic Preconditioning for Liver Transplantation: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

In recent decades, liver transplantation (LTx) has increased the survival and quality of life of patients with end-stage organ failure. Unfortunately, LTx is limited due to the shortage of donors. A lot of effort is put into finding new ways to reduce ischemia-reperfusion injury (IRI) in liver grafts to increase the number of suitable organs procured from expanded-criteria donors (ECD). The aim of this study was to systematically review the literature reporting LTx outcomes when using ischemic preconditioning (IPC) or remote ischemic preconditioning (RIPC) to reduce IRI in liver grafts.

METHODS

A literature search was performed in the MEDLINE, Web of Science, and EMBASE databases. The following combination was used: "Liver" OR "Liver Transplantation" AND "Ischemic preconditioning" OR "occlusion" OR "clamping" OR "Pringle." The following outcome data were retrieved: the rates of graft primary nonfunction (PNF), retransplantation, graft loss, and mortality; stay in hospital and the intensive care unit; and postoperative serum liver damage parameters.

RESULTS

The initial search retrieved 4,522 potentially relevant studies. After evaluating 17 full-text articles, a total of 9 randomized controlled trials (RCTs) were included (7 IPC and 2 RIPC studies) in the qualitative synthesis; the meta-analysis was only performed on the data from the IPC studies. RIPC studies had considerable methodological differences. The meta-analysis revealed the beneficial effect of IPC when comparing postoperative aspartate aminotransferase (AST) corresponding to a statistically lower mortality rate in the IPC group (odds ratio [OR] 0.51; 95% confidence interval [CI] 0.27-0.98; p = 0.04).

CONCLUSION

IPC lowers postoperative AST levels and reduces the mortality rate; however, data on the benefits of RIPC are lacking.

Contemporary strategies to assess and manage liver donor steatosis: a review

PURPOSE OF REVIEW

Due to a persistent shortage of donor livers, attention has turned toward ways of utilizing marginal grafts, particularly those with steatosis, without incurring inferior outcomes. Here we review the evaluation and utilization of steatotic liver allografts, highlight recently published data, and discuss novel methods of graft rehabilitation.

RECENT FINDINGS

Although severe liver allograft (>60%) steatosis has been associated with inferior graft and recipient outcomes, mild (<30%) steatosis has not. There is ongoing debate regarding safe utilization of grafts with moderate (30-60%) steatosis. Presently, no established protocols for evaluating steatosis in donor candidates or utilizing such grafts exist. Liver biopsy is accepted as the gold standard technique, though noninvasive methods have shown promise in accurately predicting steatosis. More recently, machine perfusion has been shown to enhance ex situ liver function and reduce steatosis, emerging as a potential means of optimizing steatotic grafts prior to transplantation.

SUMMARY

Steatotic liver allografts constitute a large proportion of deceased donor organs. Further work is necessary to define safe upper limits for the acceptable degree of steatosis, develop standardized evaluation protocols, and establish utilization guidelines that prioritize safety. Machine perfusion has shown promise in rehabilitating steatotic grafts and offers the possibility of expanding the deceased donor pool.

Pilot study of a noninvasive real-time optical backscatter probe in liver transplantation

Transplantation of severely steatotic donor livers is associated with early allograft dysfunction and poorer graft survival. Histology remains the gold standard diagnostic of donor steatosis despite the lack of consensus definition and its subjective nature. In this prospective observational study of liver transplant patients, we demonstrate the feasibility of using a handheld optical backscatter probe to assess the degree of hepatic steatosis and correlate the backscatter readings with clinical outcomes. The probe is placed on the surface of the liver and emits red and near infrared light from the tip of the device and measures the amount of backscatter of light from liver tissue via two photodiodes. Measurement of optical backscatter (Mantel-Cox P < 0.0001) and histopathological scoring of macrovesicular steatosis (Mantel-Cox P = 0.046) were predictive of 5-year graft survival. Recipients with early allograft dysfunction defined according to both Olthoff (P = 0.0067) and MEAF score (P = 0.0097) had significantly higher backscatter levels from the donor organ. Backscatter was predictive of graft loss (AUC 0.75, P = 0.0045). This study demonstrates the feasibility of real-time measurement of optical backscatter in donor livers. Early results indicate readings correlate with steatosis and may give insight to graft outcomes such as early allograft dysfunction and graft loss.

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.

Practical model to identify liver transplant recipients at low risk of postoperative haemorrhage, bile leakage and ascites

Background

This study aimed to identify a subgroup of recipients at low risk of haemorrhage, bile leakage and ascites following liver transplantation (LT).

Methods

Factors associated with significant postoperative ascites (more than 10 ml/kg on postoperative day 5), bile leakage and haemorrhage after LT were identified using three separate multivariable analyses in patients who had LT in 2010–2019. A model predicting the absence of all three outcomes was created and validated internally using bootstrap procedure.

Results

Overall, 944 recipients underwent LT. Rates of ascites, bile leakage and haemorrhage were 34.9, 7.7 and 6.0 per cent respectively. The 90-day mortality rate was 7.0 per cent. Partial liver graft (relative risk (RR) 1.31; P = 0.021), intraoperative ascites (more than 10 ml/kg suctioned after laparotomy) (RR 2.05; P = 0.001), malnutrition (RR 1.27; P = 0.006), portal vein thrombosis (RR 1.56; P = 0.024) and intraoperative blood loss greater than 1000 ml (RR 1.39; P = 0.003) were independently associated with postoperative ascites and/or bile leak and/or haemorrhage, and were introduced in the model. The model was well calibrated and predicted the absence of all three outcomes with an area under the curve of 0.76 (P = 0.001). Of the 944 patients, 218 (23.1 per cent) fulfilled the five criteria of the model, and 9.6 per cent experienced postoperative ascites (RR 0.22; P = 0.001), 1.8 per cent haemorrhage (RR 0.21; P = 0.033), 4.1 per cent bile leak (RR 0.54; P = 0.048), 40.4 per cent severe complications (RR 0.70; P = 0.001) and 1.4 per cent 90-day mortality (RR 0.13; P = 0.004).

Conclusion

A practical model has been provided to identify patients at low risk of ascites, bile leakage and haemorrhage after LT; these patients could potentially qualify for inclusion in non-abdominal drainage protocols.

Etiology of Liver Steatosis Influences the Severity of Ischemia/Reperfusion Injury and Survival After Liver Transplantation in Rats

Liver steatosis is a leading cause of graft disposal in liver transplantation, though the degree of steatosis is often the single factor determining acceptability of the graft. We investigated how the cause of liver steatosis affects graft function in rat orthotopic liver transplantation (OLT). OLT was performed using 2 types of steatotic liver grafts: the fasting and hyperalimentation (FHA) model and the methionine- and choline-deficient diet models. The FHA and 4-week feeding of a methionine- and choline-deficient diet (MCDD4wk) groups showed similar liver triglyceride levels without signs of steatohepatitis. Therefore, the 2 groups were compared in the following experiment. With 6-hour cold storage, the 7-day survival rate after OLT was far worse in the FHA than in the MCDD4wk group (0% versus 100%, P = 0.002). With 1-hour cold storage, the FHA group showed higher aspartate aminotransferase and alanine aminotransferase levels and histological injury scores in zones 1 and 2 at 24 hours after reperfusion than the normal liver and MCDD4wk groups. Intrahepatic microcirculation and tissue adenosine triphosphate levels were significantly lower in the FHA group after reperfusion. Hepatocyte necrosis, sinusoidal endothelial cell injury, and abnormal swelling of the mitochondria were also found in the FHA group after reperfusion. Tissue malondialdehyde levels were higher in the MCDD4wk group before and after reperfusion. However, the grafts up-regulated several antioxidant enzymes soon after reperfusion. Even though the degree of steatosis was equivalent, the 2 liver steatosis models possessed quite unique basal characteristics and showed completely different responses against ischemia/reperfusion injury and survival after transplantation. Our results demonstrate that the degree of fat accumulation is not a single determinant for the usability of steatotic liver grafts.

Review of Current Machine Perfusion Therapeutics for Organ Preservation

Because of the high demand of organs, the usage of marginal grafts has increased. These marginal organs have a higher risk of developing ischemia-reperfusion injury, which can lead to posttransplant complications. Ex situ machine perfusion (MP), compared with the traditional static cold storage, may better protect these organs from ischemia-reperfusion injury. In addition, MP can also act as a platform for dynamic administration of pharmacological agents or gene therapy to further improve transplant outcomes. Numerous therapeutic agents have been studied under both hypothermic (1-8°C) and normothermic settings. Here, we review all the therapeutics used during MP in different organ systems (lung, liver, kidney, heart). The major categories of therapeutic agents include vasodilators, mesenchymal stem cells, antiinflammatory agents, antiinfection agents, siRNA, and defatting agents. Numerous animal and clinical studies have examined MP therapeutic agents, some of which have even led to the successful reconditioning of discarded grafts. More clinical studies, especially randomized controlled trials, will need to be conducted in the future to solidify these promising results and to define the role of MP therapeutic agents in solid organ transplantation.

Donor PNPLA3 and TM6SF2 Variant Alleles Confer Additive Risks for Graft Steatosis After Liver Transplantation

BACKGROUND

The rs58542926 polymorphism in transmembrane 6 superfamily member 2 (TM6SF2) is a genetic factor predisposing to nonalcoholic fatty liver disease. We aimed to explore the effect of recipient and donor TM6SF2 rs58542926 genotypes on liver graft fat content after liver transplantation.

METHODS

Steatosis was evaluated in liver biopsies from 268 adult recipients. The influence of recipient and donor TM6SF2 genotypes, patatin-like phospholipase domain-containing 3 (PNPLA3) rs738409 genotypes, and nongenetic factors on the steatosis grade assessed 6-30 months after transplantation was analyzed by ordinal logistic regression.

RESULTS

The presence of the TM6SF2 c.499A allele in the donor (P = 0.014), PNPLA3 c.444G allele in the donor (P < 0.001), posttransplant body mass index (P < 0.001), and serum triglycerides (P = 0.047) independently predicted increased liver fat content on multivariable analysis, whereas noncirrhotic liver disease, as an indication for liver transplantation, was associated with lower risk of steatosis (P = 0.003). The effects of the donor TM6SF2 A and PNPLA3 G alleles were additive, with an odds ratio of 4.90 (95% confidence interval, 2.01-13.00; P < 0.001), when both minor alleles were present compared with an odds ratio of 2.22 (95% confidence interval, 1.42-3.61; P = 0.002) when only one of these alleles was present.

CONCLUSIONS

The donor TM6SF2 c.499A allele is an independent risk factor of liver graft steatosis after liver transplantation that is additive to the effects of donor PNPLA3 c.444G allele.

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

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.

Association of post-reperfusion syndrome and ischemia-reperfusion injury with acute kidney injury after liver transplantation

BACKGROUND

Acute kidney injury (AKI) is frequently observed after orthotopic liver transplantation (OLT) even in patients with previously normal renal function. In this study, we investigated the impact of factors such graft steatosis, post-reperfusion syndrome (PRS), and hepatic ischemia reperfusion injury (HIRI) on the development of AKI after OLT in adult patients.

METHODS

We retrospectively examined consecutive adult patients who underwent OLT at our institution between July 2011 and June 2017. AKI was diagnosed based on the criteria proposed by the International Kidney Disease Improving Global Outcomes (KDIGO) workgroup. Peak aspartate aminotransferase (AST) level within 72 hours after OLT was used as a surrogate marker for HIRI. Graft steatosis was diagnosed by histopathological examination using specimens biopsied intraoperatively at the end of transplantation procedure and categorized as <10%, 10%-20%, 20%-30%, and ≥30% of hepatic steatosis.

RESULTS

Out of 386 patients, 141 (37%) developed AKI (KDIGO stage 1:71 patients; stage 2:29 patients; stage 3:41 patients). Multivariable logistic regression analysis revealed that cold ischemic time (P = .012) and HIRI (P = .007) were independent risk factors for post-OLT AKI. Multivariable analysis also revealed that graft steatosis was associated with HIRI but not directly with AKI. PRS was not associated with HIRI or AKI in the multivariable analyses.

CONCLUSION

Our results indicate that greater severity of liver graft injury during transplantation negatively affects renal function after OLT. As expected, the severity of liver graft steatosis contributes to accelerated liver injury occurring during the transplantation procedure.

Outcome for Pediatric Recipients of Macrosteatotic Liver Grafts From Living Donors

In deceased donor liver transplantation, a donor liver with moderate (>30%) macrosteatosis used to be considered inappropriate for grafting. We examined the outcomes of children who underwent living donor liver transplantation (LDLT) at the National Center for Child Health and Development whose donor livers had moderate-to-severe macrosteatosis. Twelve children were enrolled who had received a moderate-to-severe macrosteatotic liver graft and underwent liver biopsy soon after LDLT. The primary diseases were biliary atresia in 7 patients, acute liver failure in 3 patients, glycogen storage disease type 1 in 1 patient, and primary sclerosing cholangitis in 1 patient. Median age was 11 months. There were 4 recipients who received grafts from their fathers, and 8 received grafts from their mothers. Median donor age was 35.5 years. We compared the degree of donor liver steatosis with the results of graft liver biopsies that were collected 4-105 days after LDLT. The levels of donor liver macrovesicular steatosis were moderate (34%-66%) in 9 patients and severe (>66%) in 3 patients. The nonalcoholic fatty liver disease activity score was 3 in 7 patients and 4 in 5 patients. Shortly after LDLT, 11 of 12 patients showed improvement in steatosis compared with the donor livers. One biopsy specimen taken 22 days after LDLT showed 60% macrosteatosis, which was the same as that in the donor liver. However, this patient was alive and well 6 years after LDLT. One patient died after LDLT because of infection and respiratory failure. The levels of steatosis of the donor liver grafts improved soon after LDLT in children, and the outcomes of children receiving a moderate-to-severe macrosteatotic liver from their parents were excellent.

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.

Liver Steatosis in Brain-Dead Donors: Progression Pattern and Affecting Factors

OBJECTIVES

No study has investigated the short-term effect of acute insulin resistance on liver steatosis in critically ill condition. We analyzed the effects of critically ill conditions of brain-dead donors (BDDs) on the development and progression of liver steatosis to investigate the influencing factors.

METHODS

This study was conducted retrospectively between January 2003 and December 2017. BDDs were for organ procurement. BDDs with body mass indexes (BMIs) < 18.5 kg/m² and ≥ 30 kg/m² were excluded. Liver steatosis was defined as ≥5% of the fat vacuole. The serum glucose level (SGL) was used to reflect insulin resistance.

RESULTS

Of the 179 BDDs, 87 (48.6%) had liver steatosis. BMI (r = 0.176, P = .019) and SGL (r = 0.267, P < .001) were correlated with steatosis. The length of the predonation period (LPDP) was negatively correlated with steatosis (r = -0.379, P < .001). BMI (odds ratio 1.266, P = .002), SGL ≥180 mg/dL (odds ratio 2.825, P = .003), and LPDP (odds ratio 0.885, P = .001) were independent risk factors for liver steatosis.

CONCLUSION

Liver steatosis is related to the SGL and BMI. Liver steatosis develops acutely in the early phase of critical illness and patients recover gradually.

Higher thresholds for the utilization of steatotic allografts in liver transplantation: Analysis from a U.S. national database

Background

Historically, liver allografts with >30% macrosteatosis (MaS) on donor biopsy have been associated with early allograft dysfunction and worse graft survival; however, successful outcomes have been reported in small cohorts. This study proposes an elevated MaS threshold for organ utilization without detriment to graft survival.

Methods

The UNOS Standard Transplant Analysis and Research database was evaluated for transplants between 2006–2015. Graft survival up to 1-year was evaluated by Kaplan-Meier (KM) survival analyses, and by univariate and multivariable logistic regression analyses, including donor and recipient characteristics. Odds ratios (OR) with 95% confidence intervals (CI) for risk of graft loss are reported.

Results

Thirty-day risk of graft loss was increased with MaS as low as 10–19% (OR [95% CI] 1.301 [1.055–1.605], p<0.0001) and peaked with MaS 50–59% (2.921 [1.672–5.103]). At 1-year, risk of graft loss remained elevated with MaS 40–49% (1.465 [1.002–2.142]) and MaS 50–59% (1.978 [1.281–3.056], p = 0.0224). Multivariable models were created for Lower and Higher MELD recipients and MaS cutoffs were established. In Lower MELD recipients, organs with ≥50% MaS had increased risk of graft loss at 30 days (2.451 [1.541–3.897], p = 0.0008) and 1-year post-transplant (1.720 [1.224–2.418], p = 0.0125). Higher MELD recipients had increased risk of graft loss at 30 days with allografts showing MaS ≥40% (4.204 [1.440–5.076], p = 0.0016). At 1-year the risk remained increased, but MaS was not significant predictor of graft loss.048 [1.131–3.710], p = 0.0616). In both MELD cohorts, organs with MaS levels below threshold had similar survival to those transplanted without a donor biopsy.

Conclusions

In conjunction with recipient selection, organs with MaS up to 50% may be safely used without detriment to outcomes.

Non-alcoholic fatty liver disease after liver transplantation in patients with non-alcoholic steatohepatitis and cryptogenic cirrhosis: the impact of pre-transplant graft steatosis

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) may occur in liver transplant recipients. This study aimed to investigate the prevalence and risk factors of NAFLD after liver transplantation in patients with NASH and cryptogenic cirrhosis, focusing on the impact of graft steatosis.

METHODS

Patients with NASH and cryptogenic cirrhosis who had undergone liver transplantation in Shiraz transplant center between March 2010 and March 2017 were included. NAFLD was diagnosed after liver transplantation using ultrasonography and transient elastography.

RESULTS

73 patients with NASH and 389 with cryptogenic cirrhosis were included. NAFLD was diagnosed in 33 patients (56.9%) in NASH group and 96 patients (26.7%) in cryptogenic group (OR: 3.61; CI: 2.04-6.39; P-Value < 0.001), using ultrasound. Obesity and post-transplant hyperlipidemia were independent predictors of NAFLD after liver transplantation (P < 0.05). NAFLD was diagnosed in 32.9% of patients with graft macrosteatosis compared to 29.9% in patients without graft macrosteatosis (OR: 1.51; 95%CI: 0.755-1.753). 28% of the patients with macrosteatosis ≥30% had NAFLD after liver transplantation compared to 31.4% with macrosteatosis <30% (OR: 1.175; 95% CI: 0.346-2.091).

CONCLUSION

Liver graft steatosis before transplantation was not associated with the occurrence of NAFLD after liver transplantation.

The role of deceased donor liver biopsy: An analysis of 5449 liver transplant recipients

BACKGROUND

No standard exists for the use of deceased donor liver biopsy during procurement. We sought to evaluate liver biopsy and the impact of findings on outcomes and graft utilization.

METHODS

A prospective observational study of donors after neurologic determination of death was conducted from 02/2012-08/2017 (16 OPOs). Donor data were collected through the UNOS Donor Management Goals Registry Web Portal and linked to the Scientific Registry of Transplant Recipients (SRTR) for recipient outcomes. Recipients of biopsied donor livers (BxDL) were studied and a Cox proportional hazard analysis was used to identify independent predictors of 1-year graft survival.

RESULTS

Data from 5449 liver transplant recipients were analyzed, of which 1791(33%) received a BxDL. There was no difference in graft or patient survival between the non-BxDL and BxDL recipient groups. On adjusted analysis of BxDL recipients, macrosteatosis (21%-30%[n = 148] and >30%[n = 92]) was not found to predict 1-year graft survival, whereas increasing donor age (HR1.02), donor Hispanic ethnicity (HR1.62), donor INR (HR1.18), and recipient life support (HR2.29) were.

CONCLUSIONS

Excellent graft and patient survival can be achieved in recipients of BxDL grafts. Notably, as demonstrated by the lack of effect of macrosteatosis on survival, donor to recipient matching may contribute to these outcomes.

Implications of Nonalcoholic Steatohepatitis as the Cause of End-Stage Liver Disease Before and After Liver Transplant

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease. Nonalcoholic steatohepatitis (NASH) is the clinically aggressive variant of NAFLD and has a propensity for fibrosis progression and cirrhosis. The prevalence of NAFLD and NASH is projected to increase rapidly in the near future and dramatically add to the already substantial health care burden. Cirrhosis and end-stage liver disease resulting from NASH is now the fastest growing indication for liver transplant (LT) in the United States. Patients with NASH cirrhosis have higher prevalence of cardiometabolic diseases. Following LT, recurrence of NAFLD and NASH is common.

An integrated perfusion machine preserves injured human livers for 1 week

The ability to preserve metabolically active livers ex vivo for 1 week or more could allow repair of poor-quality livers that would otherwise be declined for transplantation. Current approaches for normothermic perfusion can preserve human livers for only 24 h. Here we report a liver perfusion machine that integrates multiple core physiological functions, including automated management of glucose levels and oxygenation, waste-product removal and hematocrit control. We developed the machine in a stepwise fashion using pig livers. Study of multiple ex vivo parameters and early phase reperfusion in vivo demonstrated the viability of pig livers perfused for 1 week without the need for additional blood products or perfusate exchange. We tested the approach on ten injured human livers that had been declined for transplantation by all European centers. After a 7-d perfusion, six of the human livers showed preserved function as indicated by bile production, synthesis of coagulation factors, maintained cellular energy (ATP) and intact liver structure.

Livers are stored long term in a sophisticated perfusion system.

Rapid Decrease in Liver Graft Steatosis in the Early Post-transplant Period: A Blinded and Randomized Study

AIMS

Previous research suggests a rapid post-transplant decrease in liver steatosis. With increased use of liver grafts with steatosis, better understanding of this post-transplant change will facilitate successful liver transplantation. This study compares liver reperfusion biopsies with early post-transplant surveillance biopsies to evaluate and quantitate change in steatosis.

METHODS

All liver grafts with ≥ 10% steatosis were extracted for analysis. Allograft biopsies on day 0 and day 3 post-transplant were randomly read, in a blinded fashion, by a single, experienced liver pathologist. Ten non-steatotic grafts were interspersed as controls. Slides were scored for macro-, micro-, and total steatosis.

RESULTS

Overall, 151 subjects with steatosis were available for study. A decrease in steatosis was seen for most grafts: microvesicular (69%), macrovesicular (64%), and total steatosis (77%). There was a greater decrease in steatosis for grafts with high baseline steatosis (> 40% baseline steatosis with -30% reduction; 20%-39% baseline steatosis with -15% reduction; and < 20% baseline steatosis with -5% reduction).

CONCLUSIONS

These results confirm a marked post-transplant decrease in steatosis that occurs within 3 to 5 days for most liver grafts with steatosis. These findings support the continued use of liver grafts with steatosis as this pathology appears to resolve quickly after transplant.

Serum miR-33a is associated with steatosis and inflammation in patients with non-alcoholic fatty liver disease after liver transplantation

Background & aims

MiR-33a has emerged as a critical regulator of lipid homeostasis in the liver. Genetic deficiency of miR-33a aggravates liver steatosis in a preclinical model of non-alcoholic fatty liver disease (NAFLD), and relative expression of miR-33a is increased in the livers of patients with non-alcoholic steatohepatitis (NASH). It was unknown whether miR-33a is detectable in the serum of patients with NAFLD. We sought to determine whether circulating miR-33a is associated with histological hepatic steatosis, inflammation, ballooning or fibrosis, and whether it could be used as a serum marker in patients with NAFLD/NASH.

Methods

We analysed circulating miR-33a using quantitative PCR in 116 liver transplant recipients who underwent post-transplant protocol liver biopsy. Regression analysis was used to determine association of serum miR-33a with hepatic steatosis, inflammation, ballooning and fibrosis in liver biopsy.

Results

Liver graft steatosis and inflammation, but not ballooning or fibrosis, were significantly associated with serum miR-33a, dyslipidemia and insulin resistance markers on univariate analysis. Multivariate analysis showed that steatosis was independently associated with serum miR-33a, ALT, glycaemia and waist circumference, whereas inflammation was independently associated with miR-33a, HbA1 and serum triglyceride levels. Receiver operating characteristic analysis showed that exclusion of serum miR-33a from multivariate analysis resulted in non-significant reduction of prediction model accuracy of liver steatosis or inflammation.

Conclusions

Our data indicate that circulating miR-33a is an independent predictor of liver steatosis and inflammation in patients after liver transplantation. Although statistically significant, its contribution to the accuracy of prediction model employing readily available clinical and biochemical variables was limited in our cohort.

[Donor liver histology : Joint recommendations of the DGP, DTG and DSO]

BACKGROUND

The indications, implementation and reporting of liver biopsies for deceased organ donation are not mandatory or regulated. Reliable data on outcome quality and prognostic relevance are therefore not available. Defined standards are thus required to enable meaningful studies and to ensure high data quality of a national transplantation registry.

OBJECTIVE

Presentation of a synopsis of available studies and literature-based recommendations.

RESULTS AND CONCLUSION

Against the background of an organ shortage and a growing number of older donors, pretransplantation liver histology is of significant relevance to guide clinical decision making. With the joint recommendations of the German Transplantation Society (DTG), the German Society of Pathology (DGP) and the German Organ Transplantation Foundation (DSO) standardized procedures are defined for the first time.

The impact of postreperfusion syndrome during liver transplantation using livers with significant macrosteatosis

The impact of postreperfusion syndrome (PRS) during liver transplantation (LT) using donor livers with significant macrosteatosis is largely unknown. Clinical outcomes of all patients undergoing LT with donor livers with moderate macrosteatosis (30%-60%) (N = 96) between 2000 and 2017 were compared to propensity score matched cohorts of patients undergoing LT with donor livers with mild macrosteatosis (10%-29%) (N = 96) and no steatosis (N = 96). Cardiac arrest at the time of reperfusion was seen in eight (8.3%) of the patients in the moderate macrosteatosis group compared to one (1.0%) of the patients in the mild macrosteatosis group (P = .02) and zero (0%) of the patients in the no steatosis group (P = .004). Patients in the moderate macrosteatosis group had a higher rate of PRS (37.5% vs 18.8%; P = .004), early allograft dysfunction (EAD) (76.4% vs 25.8%; P < .001), renal dysfunction requiring continuous renal replacement therapy following transplant (18.8% vs 8.3%; P = .03) and return to the OR within 30 days (24.0% vs 7.3%; P = .002), than the no steatosis group. Both long-term patient (P = .30 and P = .08) and graft survival (P = .15 and P = .12) were not statistically when comparing the moderate macrosteatosis group to the mild macrosteatosis and no steatosis groups. Recipients of LT using livers with moderate macrosteatosis are at a significant increased risk of PRS. If patients are able to overcome the initial increased perioperative risk of using these donor livers, long-term graft survival does not appear to be different than matched recipients receiving grafts with no steatosis.

The dawn of liver perfusion machines

PURPOSE OF REVIEW

Despite high demand, a severe shortage of suitable allografts limits the use of liver transplantation for the treatment of end-stage liver disease. The transplant community is turning to the utilization of high-risk grafts to fill the void. This review summarizes the reemergence of ex-vivo machine perfusion for liver graft preservation, including results of recent clinical trials and its specific role for reconditioning DCD, steatotic and elderly grafts.

RECENT FINDINGS

Several phase-1 clinical trials demonstrate the safety and feasibility of machine perfusion for liver graft preservation. Machine perfusion has several advantages compared with static cold storage and may provide superior transplantation outcomes, particularly for marginal grafts. Ongoing multicenter trials aim to confirm the results of preclinical and pilot studies and establish the clinical utility of ex-vivo liver machine perfusion.

SUMMARY

Mounting evidence supports the benefits of machine perfusion for preservation of liver grafts. Thus, machine perfusion is a promising strategy to expand the donor pool by reconditioning and assessing viability of DCD, elderly and steatotic grafts during the preservation period. Additionally, machine perfusion will serve as a platform to facilitate graft intervention and modification to further optimize marginal grafts.

The Impact of Steatosis on the Outcome of Liver Transplantation: A Meta-Analysis

Background and Aims

Liver transplantation is one of the most effective treatments for end-stage liver disease as well as for cases of acute liver failure. Facing organ donor shortage, liver transplant teams had to use marginal organs. Thus, increasing availability is a key concern of donor liver grafts including steatotic livers. However, the use of steatotic liver is still controversial. The aim of this systematic review and meta-analysis was to analyze the impact of steatosis on the outcome of liver transplantation.

Methods

We searched PubMed, Cochrane Library, Embase, Web of knowledge, and so on for studies published through May 31, 2018, in which patients experienced liver transplantation using fatty liver. All studies extracted outcome indicators, and we draw conclusions by contrasting outcome indicators in different groups of steatosis. Odds ratios and 95% confidence intervals were calculated. P<0.05 was considered as statistically significant difference.

Results

19 publications were included. There was no significant difference between the group of no steatosis and mild group in primary nonfunction rate (P=0.605) or early graft dysfunction rate (P=0.44). The PNF rate was significantly higher in moderate group (P=0.003) and severe group (P <0.001) compared with that in no steatosis group. The same results were seen in early graft dysfunction rate. However, graft survival rate and patient survival rate did not differ between groups.

Conclusions

Livers with mild steatosis, even with moderate or severe steatosis, could be suitable donor under strict control of transplant conditions.