Liver Transplantation Today: Where We Are Now and Where We Are Going

Demographic Trends in Liver Transplant Survivors After 3 Decades of Program Implementation: The Impact of Cohort and Period Effects on Life Expectancy

Background

Demographic analyses may reveal current patterns of change in the outcomes of rapidly developing medical procedures because they incorporate the period perspective.

Methods

We analyzed the changes in size, age structure, and hospitalizations in the population of liver transplantation (LT) survivors in our center during the last 30 y (n = 1114 patients) and generated projections, including life expectancy (LE), considering cohort and period effects. Life tables were used to project the complete LE (overall 1990-2020 experience), the cohort LE (according to the decade of surgery: 1990-2000, 2000-2010, and 2010-2020), and the period LE (current 2015-2020 experience).

Results

The population of LT recipients in follow-up continued to experience progressive growth and aging since 1990 (492 patients [41.9% >65 y] in 2020), and the magnitude of these phenomena may double in the next 30 y. However, the number of admissions and days of admission has been decreasing. The complete LE at LT was 12.4 y, whereas the period LE was 15.8 y. The cohort LE (limited to 10 y) was 5.3, 6.3, and 7.3 y for the 1990-2000, 2000-2010, and 2010-2020 cohorts, respectively.

Conclusions

The target population of our medical care after LT is growing and aging. The prevalence of both of these phenomena is expected to increase in the coming years and is associated with a current improvement in LE. However, the hospitalization burden associated with LT survivors is declining. The period effect should be considered for generating up-to-date information on these current trends, which are crucial when designing health policies for LT survivors.

A modular simulation framework for organ allocation

BACKGROUND

We describe and validate a new simulation framework addressing important limitations of the Simulated Allocation Models (SAMs) long used to project population effects of transplant policy changes.

METHODS

We developed the Computational Open-source Model for Evaluating Transplantation (COMET), an agent-based model simulating interactions of individual donors and candidates over time to project population outcomes. COMET functionality is organized into interacting modules. Donors and candidates are synthetically generated using data-driven probability models which are adaptable to account for ongoing or hypothetical donor/candidate population trends and evolving disease management. To validate the first implementation of COMET, COMET-Lung, we attempted to reproduce lung transplant outcomes for U.S. adults from 2018-2019 and in the 6 months following adoption of the Composite Allocation Score (CAS) for lung transplant.

RESULTS

Simulated (median [Interquartile Range, IQR]) vs observed outcomes for 2018-2019 were: 0.162 [0.157, 0.167] vs 0.170 waitlist deaths per waitlist year; 1.25 [1.23, 1.28] vs 1.26 transplants per waitlist year; 0.115 [0.112, 0.118] vs 0.113 post-transplant deaths per patient year; 202 [102, 377] vs 165 nautical miles travel distance. The model accurately predicted the observed precipitous decrease in transplants received by type O lung candidates in the six months following CAS implementation.

CONCLUSIONS

COMET-Lung closely reproduced most observed outcomes. The use of synthetic populations in the COMET framework paves the way for examining possible transplant policy and clinical practice changes in populations reflecting realistic future states. Its flexible, modular nature can accelerate development of features to address specific research or policy questions across multiple organs.

Serum from patients with cirrhosis undergoing liver transplantation induces permeability in human pulmonary microvascular endothelial cells ex vivo

Introduction

Patients with cirrhosis undergoing liver transplantation frequently exhibit systemic inflammation, coagulation derangements, and edema, indicating endothelial dysfunction. This syndrome may worsen after ischemia-reperfusion injury of the liver graft, coincident with organ dysfunction that worsens patient outcomes. Little is known about changes in endothelial permeability during liver transplantation. We hypothesized that sera from these patients would increase permeability in cultured human endothelial cells ex vivo.

Methods

Adults with cirrhosis presenting for liver transplantation provided consent for blood collection during surgery. Sera were prepared at five time points spanning the entire operation. The barrier function of human pulmonary microvascular endothelial cells in culture was assessed by transendothelial resistance measured using the ECIS ZΘ system. Confluent cells from two different endothelial cell donors were stimulated with human serum from liver transplant patients. Pooled serum from healthy men and purified inflammatory agonists served as controls. The permeability response to serum was quantified as the area under the normalized resistance curve. Responses were compared between time points and analyzed for associations with clinical characteristics of liver transplant patients and their grafts.

Results

Liver transplant sera from all time points during surgery-induced permeability in both endothelial cell lines. The magnitude of permeability change was heterogeneous between patients, and there were differences in the effects of sera on the two endothelial cell lines. In one of the cell lines, the severity of liver disease was associated with greater permeability at the start of surgery. In the same cell line, serum collected 15 min after liver reperfusion induced significantly more permeability as compared to that collected at the start of surgery. Early postreperfusion sera from patients undergoing living donor transplants induced more permeability than sera from deceased donor transplants. Sera from two exemplary cases of patients on preoperative dialysis, and one patient with an unexpectedly long warm ischemia time of the liver graft, induced exaggerated and prolonged endothelial permeability.

Discussion

Serum from patients with cirrhosis undergoing liver transplantation induces permeability of cultured human pulmonary microvascular endothelial cells. Increased endothelial permeability during liver transplantation may contribute to organ injury and present a target for future therapeutics.

Research progress on the role of mitochondria in the process of hepatic ischemia-reperfusion injury

During liver ischemia-reperfusion injury, existing mechanisms involved oxidative stress, calcium overload, and the activation of inflammatory responses involve mitochondrial injury. Mitochondrial autophagy, a process that maintains the normal physiological activity of mitochondria, promotes cellular metabolism, improves cellular function, and facilitates organelle renewal. Mitochondrial autophagy is involved in oxidative stress and apoptosis, of which the PINK1-Parkin pathway is a major regulatory pathway, and the deletion of PINK1 and Parkin increases mitochondrial damage, reactive oxygen species production, and inflammatory response, playing an important role in mitochondrial quality regulation. In addition, proper mitochondrial permeability translational cycle regulation can help maintain mitochondrial stability and mitigate hepatocyte death during ischemia-reperfusion injury. This mechanism is also closely related to oxidative stress, calcium overload, and the aforementioned autophagy pathway, all of which leads to the augmentation of the mitochondrial membrane permeability transition pore opening and cause apoptosis. Moreover, the release of mitochondrial DNA (mtDNA) due to oxidative stress further aggravates mitochondrial function impairment. Mitochondrial fission and fusion are non-negligible processes required to maintain the dynamic renewal of mitochondria and are essential to the dynamic stability of these organelles. The Bcl-2 protein family also plays an important regulatory role in the mitochondrial apoptosis signaling pathway. A series of complex mechanisms work together to cause hepatic ischemia-reperfusion injury (HIRI). This article reviews the role of mitochondria in HIRI, hoping to provide new therapeutic clues for alleviating HIRI in clinical practice.

National Trends in Utilization of Normothermic Machine Perfusion in DCD Liver Transplantation

Background

In liver transplantation, advances in ex situ normothermic machine perfusion (NMP) have improved outcomes compared with traditional static cold storage (SCS) in donation after circulatory death (DCD) organs. We aimed to characterize trends in the utilization of NMP versus SCS in DCD liver transplantation in the United States.

Methods

This retrospective cohort study used data from the United Network for Organ Sharing database to identify recipient-donor adult liver transplant pairs from DCD donors from January 2016 to June 2022. Utilization of NMP and changes in donor risk index (DRI) and components between NMP and SCS were assessed across transplant year eras (2016-2018, 2019-2020, and 2021-2022). Statistical comparisons were made using the Kruskal-Wallis test or the chi-square test.

Results

A total of 3937 SCS and 127 NMP DCD donor transplants were included. Utilization of NMP ranged from ~0.4% to 3.5% from 2016 to 2021 and rose significantly to 11.2% in early 2022. Across transplant eras, median DRI increased significantly for SCS and NMP, but the magnitude of the increase was larger for NMP. With NMP DCDs, there were significant increases in median donor age, national share proportion, and "cold ischemic time" over time. Finally, there was a shift toward including higher DRI donors and higher model for end-stage liver disease score transplant recipients with NMP in later transplant eras.

Conclusions

In recent years, NMP utilization has increased and expanded to donors with higher DRI and recipients with higher model for end-stage liver disease score at transplant, suggesting increasing familiarity and risk tolerance with NMP technology. As NMP remains a relatively new technique, ongoing study of patient outcomes, organ allocation practices, and utilization patterns is critical.

Improve the prediction of liver transplant mortality based on pre-transplant factors: A multi-center study from China: Mortality prediction of LT

AIMS

To designed a new model using pre-transplant data to predict post-transplant mortality for Chinese population and compared its performance to that of existing models.

METHODS

In this multicenter study, 544 recipients of liver transplants for non-tumor indications were enrolled in the training group and 276 patients in the validation group. The new Simplified Mortality Prediction Scores (SMOPS) model was compared to the MELD and four existing models using the C-statistic.

RESULTS

SMOPS model used 6 independent pre-transplantation risk factors screened from the training group (chronic liver failure/organ failure scores, fever > 37.6 ℃, ABO blood-type compatibility, arterial lactate level, leukocyte count and re-transplantation). The SMOPS accurately predicted patients' 30-day, 90-day and 365-day mortality following liver transplantation, and its' scores were more accurate than those of the other models. The SMOPS generated four levels of risk: low risk (<10 points), moderate risk (11-20 points), high risk (21-25 points) and futile risk (≥26 points). The survival within all risk levels was not different between MELD=40 and MELD<40. The survival within moderate-, high- or extreme-risk ALF was not different between ALF and non-ALF.

CONCLUSION

The SMOPS model uses pre-transplant risk factors to stratify post-transplant survival and is superior to current models for Chinese population, and has the potential to contribute to improvements in organ-allocation policies.

Current Understanding of Marginal Grafts in Liver Transplantation

End-stage liver disease (ESLD), stemming from a spectrum of chronic liver pathologies including chronic liver failure, acute cirrhosis decompensation and hepatocellular carcinoma, imposes a significant global healthcare burden. Liver transplantation (LT) remains the only treatment for ESLD. However, the escalating mortality on transplant waitlists has prompted the utilization of marginal liver grafts in LT procedures. These grafts primarily encompass elderly livers, steatotic livers, livers from donation after circulatory death, split livers and those infected with the hepatitis virus. While the expansion of the donor pool offers promise, it also introduces concomitant risks. These encompass graft failure, biliary and cardiovascular complications, the recurrence of liver disease and reduced patient and graft survival. Consequently, various established strategies, ranging from improved donor-recipient matching to surgical interventions, have emerged to mitigate these risks. This article undertakes a comprehensive assessment of the current landscape, evaluating the viability of diverse marginal liver grafts. Additionally, it synthesizes approaches aimed at enhancing the quality of such marginal liver grafts. The overarching objective is to augment the donor pool and ameliorate the risk factors associated with the shortage of liver grafts.

Perioperative Cardiovascular Risk Assessment and Management in Liver Transplant Recipients: A Review of the Literature Merging Guidelines and Interventions

Liver transplantation (LT) is the second most performed solid organ transplant. Coronary artery disease (CAD) is a critical consideration for LT candidacy, particularly in patients with known CAD or risk factors, including metabolic dysfunction associated with steatotic liver disease. The presence of severe CAD may exclude patients from LT; therefore, precise preoperative evaluation and interventions are necessary to achieve transplant candidacy. Cardiovascular complications represent the earliest nongraft-related cause of death post-transplantation. Timely intervention to reduce cardiovascular events depends on adequate CAD screening. Coronary disease screening in end-stage liver disease is challenging because standard noninvasive CAD screening tests have low sensitivity due to hyperdynamic state and vasodilatation. As a result, there is overuse of invasive coronary angiography to exclude severe CAD. Coronary artery calcium scoring using a computed tomography scan is a tool for the prediction of cardiovascular events, and can be used to achieve risk stratification in LT candidates. Recent literature shows that qualitative assessment on both noncontrast- and contrast-enhanced chest computed tomography can be used instead of calcium score to assess the presence of coronary calcium. With increasing prevalence, protocols to address CAD in LT candidates must be reconsidered. Percutaneous coronary intervention could allow a shorter duration of dual-antiplatelet therapy in simple lesions, with safer perioperative outcomes. Hybrid coronary revascularization is an option for high-risk LT candidates with multivessel disease nonamenable to percutaneous coronary intervention. The objective of this review is to evaluate existing methods for preoperative cardiovascular risk stratification, and to describe interventions before surgery to optimize patient outcomes and reduce cardiovascular event risk.

Creating synthetic populations in transplantation: A Bayesian approach enabling simulation without registry re-sampling

Computer simulation has played a pivotal role in analyzing alternative organ allocation strategies in transplantation. The current approach to producing cohorts of organ donors and candidates for individual-level simulation requires directly re-sampling retrospective data from a transplant registry. This historical data may reflect outmoded policies and practices as well as systemic inequities in candidate listing, limiting contemporary applicability of simulation results. We describe the development of an alternative approach for generating synthetic donors and candidates using hierarchical Bayesian network probability models. We developed two Bayesian networks to model dependencies among 10 donor and 36 candidate characteristics relevant to waitlist survival, donor-candidate matching, and post-transplant survival. We estimated parameters for each model using Scientific Registry of Transplant Recipients (SRTR) data. For 100 donor and 100 candidate synthetic populations generated, proportions for each categorical donor or candidate attribute, respectively, fell within one percentage point of observed values; the interquartile ranges (IQRs) of each continuous variable contained the corresponding SRTR observed median. Comparisons of synthetic to observed stratified distributions demonstrated the ability of the method to capture complex joint variability among multiple characteristics. We also demonstrated how changing two upstream population parameters can exert cascading effects on multiple relevant clinical variables in a synthetic population. Generating synthetic donor and candidate populations in transplant simulation may help overcome critical limitations related to the re-sampling of historical data, allowing developers and decision makers to customize the parameters of these populations to reflect realistic or hypothetical future states.

Improving the radiological diagnosis of hepatic artery thrombosis after liver transplantation: Current approaches and future challenges

Hepatic artery thrombosis (HAT) is a devastating vascular complication following liver transplantation, requiring prompt diagnosis and rapid revascularization treatment to prevent graft loss. At present, imaging modalities such as ultrasound, computed tomography, and magnetic resonance play crucial roles in diagnosing HAT. Although imaging techniques have improved sensitivity and specificity for HAT diagnosis, they have limitations that hinder the timely diagnosis of this complication. In this sense, the emergence of artificial intelligence (AI) presents a transformative opportunity to address these diagnostic limitations. The develo pment of machine learning algorithms and deep neural networks has demon strated the potential to enhance the precision diagnosis of liver transplant com plications, enabling quicker and more accurate detection of HAT. This article examines the current landscape of imaging diagnostic techniques for HAT and explores the emerging role of AI in addressing future challenges in the diagnosis of HAT after liver transplant.

Optimizing nutrition in hepatic cirrhosis: A comprehensive assessment and care approach

Cirrhosis is considered a growing cause of morbidity and mortality, which represents a significant public health problem. Currently, there is no effective treatment to reverse cirrhosis. Treatment primarily centers on addressing the underlying liver condition, monitoring, and managing portal hypertension-related complications, and evaluating the potential for liver transplantation in cases of decompensated cirrhosis, marked by rapid progression and the emergence of complications like variceal bleeding, hepatic encephalopathy, ascites, malnutrition, and more. Malnutrition, a prevalent complication across all disease stages, is often underdiagnosed in cirrhosis due to the complexities of nutritional assessment in patients with fluid retention and/or obesity, despite its crucial impact on prognosis. Increasing emphasis has been placed on the collaboration of nutritionists within hepatology and Liver transplant teams to deliver comprehensive care, a practice that has shown to improve outcomes. This review covers appropriate screening and assessment methods for evaluating the nutritional status of this population, diagnostic approaches for malnutrition, and context-specific nutrition treatments. It also discusses evidence-based recommendations for supplementation and physical exercise, both essential elements of the standard care provided to cirrhotic patients.

Integrated multi-omic analysis identifies fatty acid binding protein 4 as a biomarker and therapeutic target of ischemia-reperfusion injury in steatotic liver transplantation

BACKGROUND AND AIMS

Due to a lack of donor grafts, steatotic livers are used more often for liver transplantation (LT). However, steatotic donor livers are more sensitive to ischemia-reperfusion (IR) injury and have a worse prognosis after LT. Efforts to optimize steatotic liver grafts by identifying injury targets and interventions have become a hot issue.

METHODS

Mouse LT models were established, and 4D label-free proteome sequencing was performed for four groups: normal control (NC) SHAM, high-fat (HF) SHAM, NC LT, and HF LT to screen molecular targets for aggravating liver injury in steatotic LT. Expression detection of molecular targets was performed based on liver specimens from 110 donors to verify its impact on the overall survival of recipients. Pharmacological intervention using small-molecule inhibitors on an injury-related target was used to evaluate the therapeutic effect. Transcriptomics and metabolomics were performed to explore the regulatory network and further integrated bioinformatics analysis and multiplex immunofluorescence were adopted to assess the regulation of pathways and organelles.

RESULTS

HF LT group represented worse liver function compared with NC LT group, including more apoptotic hepatocytes (P < 0.01) and higher serum transaminase (P < 0.05). Proteomic results revealed that the mitochondrial membrane, endocytosis, and oxidative phosphorylation pathways were upregulated in HF LT group. Fatty acid binding protein 4 (FABP4) was identified as a hypoxia-inducible protein (fold change > 2 and P < 0.05) that sensitized mice to IR injury in steatotic LT. The overall survival of recipients using liver grafts with high expression of FABP4 was significantly worse than low expression of FABP4 (68.5 vs. 87.3%, P < 0.05). Adoption of FABP4 inhibitor could protect the steatotic liver from IR injury during transplantation, including reducing hepatocyte apoptosis, reducing serum transaminase (P < 0.05), and alleviating oxidative stress damage (P < 0.01). According to integrated transcriptomics and metabolomics analysis, cAMP signaling pathway was enriched following FABP4 inhibitor use. The activation of cAMP signaling pathway was validated. Microscopy and immunofluorescence staining results suggested that FABP4 inhibitors could regulate mitochondrial membrane homeostasis in steatotic LT.

CONCLUSIONS

FABP4 was identified as a hypoxia-inducible protein that sensitized steatotic liver grafts to IR injury. The FABP4 inhibitor, BMS-309403, could activate of cAMP signaling pathway thereby modulating mitochondrial membrane homeostasis, reducing oxidative stress injury in steatotic donors.

The effects of venovenous bypass use in liver transplantation with piggyback technique: a propensity score-weighted analysis

Venovenous bypass (VVB) use during liver transplantation (LT) is notably variable among the centres and it is actually restricted to surgically complex cases, severely unstable recipients or grafts from high-risk donors. Historically, VVB was associated with the classical LT with caval cross clamping, while not much is known about the safety of this technique applied to piggyback LT. This retrospective observational study evaluated the effects of VVB applied to piggyback LT on mortality, hospital outcomes, postoperative graft and other organ dysfunction. We retrospectively collected data about recipient status, surgical complexity and graft quality of all the piggyback LTs performed at the Transplant Unit of IRCCS Azienda Ospedaliero-Universitaria di Bologna, Italy, from January 2012 to December 2022. A propensity score (PS) was built taking into account the variables possibly associated with either VVB choice and the investigated outcomes with the average treatment overlap method. PS-weighted general linear models (GLMs) were developed to investigate the adjusted effect of VVB use on the selected outcomes. The final analysis included 874 LT cases, of whom 74 (8.5%) underwent VVB. The effective sample sizes after PS-weighting were 280.2 and 64.3 patients in the no-VVB and VVB groups, respectively. PS-weighted GLMs did not show any differences regarding hospital and graft-related outcomes. However, significantly higher odds ratios for serum creatinine > 2 mg/dL and AKIN stage 2 or 3 during the first 24 h after ICU admission together with a higher renal replacement therapy need during ICU stay were reported for VVB exposure in the weighted analyses. This study suggests similar mortality and length of stay but a higher risk for postoperative acute kidney injury in patients undergoing piggyback LT with VVB.

Salvianolic acid B attenuates liver fibrosis by targeting Ecm1 and inhibiting hepatocyte ferroptosis

Hepatocyte ferroptosis promotes the pathogenesis and progression of liver fibrosis. Salvianolic acid B (Sal B) exerts antifibrotic effects. However, the pharmacological mechanism and target has not yet been fully elucidated. In this study, liver fibrosis was induced by CCl4 in wild-type mice and hepatocyte-specific extracellular matrix protein 1 (Ecm1)-deficient mice, which were separately treated with Sal B, ferrostatin-1, sorafenib or cilengitide. Erastin- or CCl4-induced hepatocyte ferroptosis models with or without Ecm1 gene knockdown were evaluated in vitro. Subsequently, the interaction between Ecm1 and xCT and the binding kinetics of Sal B and Ecm1 were determined. We found that Sal B significantly attenuated liver fibrosis in CCl4-induced mice. Ecm1 deletion in hepatocytes abolished the antifibrotic effect of Sal B. Mechanistically, Sal B protected against hepatocyte ferroptosis by upregulating Ecm1. Further research revealed that Ecm1 as a direct target for treating liver fibrosis with Sal B. Interestingly, Ecm1 interacted with xCT to regulate hepatocyte ferroptosis. Hepatocyte ferroptosis in vitro was significantly attenuated by Sal B treatment, which was abrogated after knockdown of Ecm1 in LO2 cells. Therefore, Sal B alleviates liver fibrosis in mice by targeting up-regulation of Ecm1 and inhibiting hepatocyte ferroptosis. The interaction between Ecm1 and xCT regulates hepatocyte ferroptosis.

Survival following liver transplantation: A population-based nested case-control study

BACKGROUND

Liver transplantation is the gold standard treatment for end-stage liver disease. This study evaluates post-transplantation survival compared with the general population by quantifying standardized mortality ratios in a nested case-control study.

METHODS

Controls were noninstitutionalized United States inhabitants from the National Longitudinal Mortality Study. Cases underwent liver transplantation from 1990 to 2007 identified through the Organ Procurement and Transplantation Network database. Propensity matching (5:1, nearest neighbor, caliper 0.1) identified controls based on age, sex, race, and state. The primary endpoint was 10-year survival.

RESULTS

62,788 cases were matched to 313,381 controls. The overall standardized mortality ratio was 2.46 (95% CI ​= ​2.44-2.48). The standardized mortality ratio was higher for males (2.59 vs. 2.25) and Hispanic patients (4.80). Younger patients and those transplanted earlier (1990-1995) had higher standardized mortality ratios.

CONCLUSIONS

Liver recipients have a standardized mortality ratio 2.46 times higher than the general population. Long-term mortality has declined over time.

Role of Transjugular Intrahepatic Portosystemic Shunt in the Liver Transplant Setting

Liver transplantation is currently the only curative therapy for patients with liver cirrhosis. Not all patients in the natural course of the disease will undergo transplantation, but the majority of them will experience portal hypertension and its complications. In addition to medical and endoscopic therapy, a key role in managing these complications is played by the placement of a transjugular intrahepatic portosystemic shunt (TIPS). Some indications for TIPS placement are well-established, and they are expanding and broadening over time. This review aims to describe the role of TIPS in managing patients with liver cirrhosis, in light of liver transplantation. As far as it is known, TIPS placement seems not to affect the surgical aspects of liver transplantation, in terms of intraoperative bleeding rates, postoperative complications, or length of stay in the Intensive Care Unit. However, the placement of a TIPS "towards transplant" can offer advantages in terms of ameliorating a patient's clinical condition at the time of transplantation and improving patient survival. Additionally, the TIPS procedure can help preserve the technical feasibility of the transplant itself. In this context, indications for TIPS placement at an earlier stage are drawing particular attention. However, TIPS insertion in decompensated patients can also lead to serious adverse events. For these reasons, further studies are needed to make reliable recommendations for TIPS in the pre-transplant setting.

Mothers' experiences of caring for their children with liver transplantation: From sorrow to new determination

This study aims to understand mothers' dynamic experiences of caring for their children with liver transplant. A descriptive phenomenological qualitative approach was applied to this study. A total of seven mothers participated in this study. Data were collected from April 2020 to June 2020 through face-to-face interviews. Data analysis was performed using Giorgi's phenomenological method. By grouping general meaning units, 8 themes and 19 subthemes were derived. Eight themes are as follows: sorrow and distress of accepting a child's diagnosis; difficulties in deciding to undergo liver transplantation; negative emotions before and after transplant; the support system before and after liver transplantation; achieving a sense of trust toward healthcare providers; new concerns about the child's life after undergoing liver transplantation; appreciation of the experience; and new determination and expectations for future life. This study can contribute to the guideline that describes the role and daily life experiences of caregiving for other parents whose children undergo liver transplantation and nurses who work with impacted families. Healthcare providers can refer to the results to provide liver transplantation childcare and hospital-based support groups for child's family to improve nurses' communication skills.

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.

Heme Oxygenase-1-Modified BMMSCs Activate AMPK-Nrf2-FTH1 to Reduce Severe Steatotic Liver Ischemia-Reperfusion Injury

BACKGROUND

Ischemia-reperfusion injury (IRI) is an important cause of graft dysfunction post-liver transplantation, where donor liver with severe steatosis is more sensitive to IRI. Liver IRI involves ferroptosis and can be alleviated by heme oxygenase-1-modified bone marrow mesenchymal stem cells (HO-1/BMMSCs).

AIMS

To explore the role and mechanism of HO-1/BMMSCs in severe steatotic liver IRI.

METHODS

A severe steatotic liver IRI rat model and a hypoxia/reoxygenation (H/R) of severe steatosis hepatocyte model were established. Liver and hepatocyte damage was evaluated via liver histopathology and cell activity. Ferroptosis was evaluated through ferroptosis indexes. Nuclear factor erythroid 2-related factor 2 (Nrf2) was knocked down in severe steatotic hepatocytes. The role of Nrf2 and AMPK in HO-1/BMMSC inhibition of ferroptosis was examined using the AMP-activated protein kinase (AMPK) pathway inhibitor Compound C.

RESULTS

The HO-1/BMMSCs alleviated severe steatotic liver IRI and ferroptosis. HO-1/BMMSCs promoted ferritin heavy chain 1(FTH1), Nrf2, and phosphorylated (p)-AMPK expression in the H/R severe steatotic hepatocytes. Nrf2 knockdown decreased FTH1 expression levels but did not significantly affect p-AMPK expression levels. The protective effect of HO-1/BMMSCs against H/R injury in severe steatotic hepatocytes and the inhibitory effect on ferroptosis were reduced. Compound C decreased p-AMPK, Nrf2, and FTH1 expression levels, weakened the HO-1/BMMSC protective effect against severe steatotic liver IRI and H/R-injured severe steatotic hepatocytes, and reduced the inhibition of ferroptosis.

CONCLUSIONS

Ferroptosis was involved in HO-1/BMMSC reduction of severe steatotic liver IRI. HO-1/BMMSCs protected against severe steatotic liver IRI by inhibiting ferroptosis through the AMPK-Nrf2-FTH1 pathway. HO-1/BMMSCs activate AMPK, which activates Nrf2, promotes its nuclear transcription, then promotes the expression of its downstream protein FTH1, thereby inhibiting ferroptosis and attenuating severe steatotic liver IRI in rats. Glu: glutamic acid; Cys: cystine; GSH: glutathione; GPX4: glutathione peroxidase 4; HO-1/BMMSCs: HO-1-modified BMMSCs; Fer-1: ferrostatin-1; DFO: deferoxamine; FTH1: ferritin heavy chain1; p-AMPK: phosphorylated AMP-activated protein kinase; Nrf2: nuclear factor erythroid 2-related factor 2; IRI: ischemia-reperfusion injury; MCD: methionine-choline deficiency.

Defatting of Human Livers During Long-Term e x situ Normothermic Perfusion: Novel Strategy to Rescue Discarded Organs for Transplantation

OBJECTIVE

To develop a protocol for the defatting of steatotic liver grafts during long-term ex situ normothermic machine perfusion.

BACKGROUND

Despite the alarming increase in donor organ shortage, the highly prevalent fatty liver grafts are often discarded due to the risk of primary nonfunction. Effective strategies preventing such outcomes are currently lacking. An exciting new avenue is the introduction of ex situ normothermic machine perfusion (NMP), enabling a liver to remain fully functional for up to 2 weeks and providing a unique window of opportunity for defatting before transplantation.

METHODS

Over a 5-year period, 23 discarded liver grafts and 28 partial livers from our resection program were tested during ex situ normothermic machine perfusion. The steatosis degree was determined on serial biopsies by expert pathologists, and triglyceride contents were measured simultaneously.

RESULTS

Of 51 liver grafts, 20 were steatotic, with up to 85% macrovesicular steatosis, and were perfused for up to 12 days. Ten livers displayed marked (5 of which almost complete) loss of fat, while the other 10 did not respond to long-term perfusion. Successful defatting was related to prolonged perfusion, automated glucose control, circadian nutrition, and L-carnitine/fenofibrate supplementation. Pseudopeliotic steatosis and the associated activation of Kupffer/stellate cells were unexpected processes that might contribute to defatting. Synthetic and metabolic functions remained preserved for most grafts until perfusion ended.

CONCLUSION

Ex situ long-term perfusion effectively reduces steatosis while preserving organ viability and may in the future allow transplantation of primarily unusable high-risk grafts, significantly increasing the number of organs available for transplantation.

Whole Liver Derived Acellular Extracellular Matrix for Bioengineering of Liver Constructs: An Updated Review

Biomaterial templates play a critical role in establishing and bioinstructing three-dimensional cellular growth, proliferation and spatial morphogenetic processes that culminate in the development of physiologically relevant in vitro liver models. Various natural and synthetic polymeric biomaterials are currently available to construct biomimetic cell culture environments to investigate hepatic cell-matrix interactions, drug response assessment, toxicity, and disease mechanisms. One specific class of natural biomaterials consists of the decellularized liver extracellular matrix (dECM) derived from xenogeneic or allogeneic sources, which is rich in bioconstituents essential for the ultrastructural stability, function, repair, and regeneration of tissues/organs. Considering the significance of the key design blueprints of organ-specific acellular substrates for physiologically active graft reconstruction, herein we showcased the latest updates in the field of liver decellularization-recellularization technologies. Overall, this review highlights the potential of acellular matrix as a promising biomaterial in light of recent advances in the preparation of liver-specific whole organ scaffolds. The review concludes with a discussion of the challenges and future prospects of liver-specific decellularized materials in the direction of translational research.

Survival Benefit of Solid-Organ Transplantation: 10-Year Update

IMPORTANCE

Transplantation has transformed into a burgeoning field that is rapidly evolving to optimize organ distribution and survival outcomes. The years since 2012 (the last comprehensive study) have seen changes in transplantation, such as advances in immunotherapy and novel indices, that necessitate an updated analysis of survival benefit.

DESIGN

Our goal was to determine the survival benefit for solid-organ transplants in the United Network for Organ Sharing (UNOS) database for a three decade period and provide updates on advancements since 2012. Our retrospective analysis examined data containing U.S. patient records from September 1, 1987, to September 1, 2021.

RESULTS

We found that 3,430,272 life-years were saved over our transplant period (4.33 life-years saved per patient); kidney-1,998,492 life-years; liver -767,414; heart-435,312; lung-116,625; pancreas-kidney-123,463; pancreas-30,575; intestine-7901. After matching, 3,296,851 life-years were saved. Life-years saved and median survival increased for all organs between 2012 and 2021. Compared to 2012, median survival increased in kidney (from 12.4 to 14.76 years), liver (from 11.6 to 14.59), heart (9.5 to 11.73), lung (5.2 to 5.63), pancreas-kidney (from 14.5 to 16.88), pancreas (from 13.3 to 16.10). When compared to 2012, the percent transplanted increased in kidney, liver, heart, lung, and intestine, while pancreas-kidney and pancreas show decreased percent transplanted.

CONCLUSION

Our study underscores the tremendous survival benefits of solid organ transplantation (over 3.4 million life-years saved) and shows improvements since 2012. Our study also highlights areas of transplantation, notably pancreas transplants, that may necessitate reinvigorated attention.

Geographic disparities in access to liver transplantation

Since the Final Rule regarding transplantation was published in 1999, organ distribution policies have been implemented to reduce geographic disparity. While a recent change in liver allocation, termed acuity circles, eliminated the donor service area as a unit of distribution to decrease the geographic disparity of waitlisted patients to liver transplantation, recently published results highlight the complexity of addressing geographic disparity. From geographic variation in donor supply, as well as liver disease burden and differing model for end-stage liver disease (MELD) scores of candidates and MELD scores necessary to receive liver transplantation, to the urban-rural disparity in specialty care access, and to neighborhood deprivation (community measure of socioeconomic status) in liver transplant access, addressing disparities of access will require a multipronged approach at the patient, transplant center, and national level. Herein, we review the current knowledge of these disparities-from variation in larger (regional) to smaller (census tract or zip code) levels to the common etiologies of liver disease, which are particularly affected by these geographic boundaries. The geographic disparity in liver transplant access must balance the limited organ supply with the growing demand. We must identify patient-level factors that contribute to their geographic disparity and incorporate these findings at the transplant center level to develop targeted interventions. We must simultaneously work at the national level to standardize and share patient data (including socioeconomic status and geographic social deprivation indices) to better understand the factors that contribute to the geographic disparity. The complex interplay between organ distribution policy, referral patterns, and variable waitlisting practices with the proportion of high MELD patients and differences in potential donor supply must all be considered to create a national policy strategy to address the inequities in the system.

Donor hepatic artery reconstruction based on human embryology: A case report

BACKGROUND

Embryonic hepatic artery anatomy simplifies its identification during liver transplantation. Injuries to the donor hepatic artery can cause complications in this process. The hepatic artery's complex anatomy in adults makes this step challenging; however, during embryonic development, the artery and its branches have a simpler relationship. By restoring the embryonic hepatic artery anatomy, surgeons can reduce the risk of damage and increase the procedure's success rate. This approach can lead to improved patient outcomes and lower complication rates.

CASE SUMMARY

In this study, we report a case of donor liver preparation using a donor hepatic artery preparation based on human embryology. During the preparation of the hepatic artery, we restored the anatomy of the celiac trunk, superior mesenteric artery, and their branches to the state of the embryo at 5 wk. This allowed us to dissect the variant hepatic artery from the superior mesenteric artery and left gastric artery during the operation. After implanting the donor liver into the recipient, we observed normal blood flow in the donor hepatic artery, main hepatic artery, and variant hepatic artery, without any leakage.

CONCLUSION

Donor hepatic artery preparation based on human embryology can help reduce the incidence of donor hepatic artery injuries during liver transplantation.

Role of Kupffer cells in tolerance induction after liver transplantation

Currently, liver transplantation has reached a level of maturity where it is considered an effective treatment for end-stage liver disease and can significantly prolong the survival time of patients. However, acute and chronic rejection remain major obstacles to its efficacy. Although long-term use of immunosuppressants can prevent rejection, it is associated with serious side effects and significant economic burden for patients. Therefore, the investigation of induced immune tolerance holds crucial theoretical significance and socio-economic value. In fact, the establishment of immune tolerance in liver transplantation is intricately linked to the unique innate immune system of the liver. Kupffer cells, as a crucial component of this system, play a pivotal role in maintaining the delicate balance between inflammatory response and immune tolerance following liver transplantation. The important roles of different functions of Kupffer cells, such as phagocytosis, cell polarization, antigen presentation and cell membrane proteins, in the establishment of immune tolerance after transplantation is comprehensively summarized in this paper. Providing theoretical basis for further study and clinical application of Kupffer cells in liver transplantation.

Ex Vivo Perfusion of Porcine Pancreas and Liver Sourced from Commercial Abattoirs after Circulatory Death as a Research Resource: A Methodological Study

BACKGROUND

Machine perfusion (MP) is increasingly used for human transplant organ preservation. The use of MP for research purposes is another opportunity for this technology. The porcine pancreas and liver are similar in anatomical size and function to their human counterparts, making them an excellent resource for research, but they have some important differences from human organs which can influence their research use. In this paper, we describe a technique developed and tested for the retrieval of porcine organs for use in research on perfused viable organs.

METHODS

Whole-organ porcine pancreata and livers were harvested at a commercial abattoir, following standard slaughterhouse processes. The standard slaughterhouse process involved a thoracotomy and mid-line laparotomy, and all the thoracoabdominal organs were removed. The pancreas, fixed in the retroperitoneum, was carefully dissected from its attachments to the surrounding structures, and tissue planes between the pancreas, spleen, duodenum, and colon were meticulously identified and dissected. Vessel exposure and division: The aorta, portal vein (PV), hepatic vein (HV), and hepatic artery (HA) were dissected and isolated, preserving the input and output channels for the liver and pancreas. A distal 3 cm of the aorta was preserved and divided and served as the input for the pancreas perfusions. The liver, PV, HV, and HA were preserved and divided to preserve the physiological channels of the input (PV and HA) and output (HV) for the liver perfusions. The porcine hepatic and pancreas anatomy shares significant resemblance with the gross anatomy found in humans, and this was taken into consideration when designing the perfusion circuitry. The porcine pancreas and spleen shared a common blood supply, with branches arising from the splenic artery. The organs were flushed with cold, heparinised normal saline and transported in a temperature-regulated receptacle maintained at a core temperature between 4 and 8 °C, in line with the standards of static cold storage (SCS), to a dedicated perfusion lab and perfused using our novel perfusion machine with autologous, heparinised porcine blood, also collected at the abattoir.

The Practice of Fast-Track Liver Transplant Anesthesia

Prior to the 1990s, prolonged postoperative intubation and admission to the intensive care unit was considered the standard of care following liver transplantation. Advocates of this practice speculated that this time allowed patients to recover from the stress of major surgery and allowed their clinicians to optimize the recipients' hemodynamics. As evidence in the cardiac surgical literature on the feasibility of early extubation grew, clinicians began applying these principles to liver transplant recipients. Further, some centers also began challenging the dogma that patients need to be cared for in the intensive care unit following liver transplantation and instead transferred patients to the floor or stepdown units immediately following surgery, a technique known as "fast-track" liver transplantation. This article aims to provide a history of early extubation for liver transplant recipients and offer practical advice on how to select patients that may be able to bypass the intensive care unit and be recovered in a non-traditional manner.

Alcohol-related hepatitis: A review article

Alcohol-related hepatitis (ARH) is a unique type of alcohol-associated liver disease characterized by acute liver inflammation caused by significant alcohol use. It ranges in severity from mild to severe and carries significant morbidity and mortality. The refinement of scoring systems has enhanced prognostication and guidance of clinical decision-making in the treatment of this complex disease. Although treatment focuses on supportive care, steroids have shown benefit in select circumstances. There has been a recent interest in this disease process, as coronavirus disease 2019 pandemic led to substantial rise in cases. Although much is known regarding the pathogenesis, prognosis remains grim due to limited treatment options. This article summarizes the epidemiology, genetics, pathogenesis, diagnosis and treatment of ARH.

Long term outcomes after normothermic machine perfusion in liver transplantation -experience at a single North American centre

Normothermic machine perfusion (NMP) has emerged as a valuable tool in the preservation of liver allografts before transplantation. Randomized trials have shown that replacing static cold storage (SCS) with NMP reduces allograft injury and improves graft utilization. The University of Alberta's liver transplant program was one of the early adopters of NMP in North America. Herein, we describe our seven-year experience applying NMP to extend preservation time in liver transplantation using a 'back-to-base' approach. From 2015 to 2021, 79 livers were transplanted following NMP compared to 386 after SCS only. NMP livers were preserved for a median time of 847min compared to 288.5min in the SCS cohort (p<0.0001). Despite this, we observed significantly improved 30-day graft survival (p=0.030), though no differences in long term patient survival, major complications or biliary or vascular complications. We also found that while SCS time was strongly associated with increased graft failure at one year in the SCS cohort (p=0.006), there was no such association amongst NMP livers (p=0.171). Our experience suggests that NMP can safely extend the total preservation time of liver allografts without increasing complications.

Surgical resection for large hepatocellular carcinoma and those beyond BCLC: systematic review with proposed management algorithm

BACKGROUND

Hepatocellular carcinoma (HCC) accounts for the sixth most common cancer and ranks third in mortality worldwide with inhomogeneity in terms of resection for advanced-stage disease.

METHODS

A systematic review of published literature using the PubMed, Medline, and Google Scholar databases from 1995 to 2020 was conducted to identify studies that reported outcomes of resection for solitary HCC > 10 cm, BCLC B/C, and multinodular HCC. Our aim was to assess overall survival for resection, identify poor prognostic factors, and to compare it to trans-arterial chemotherapy (TACE) where data was available.

RESULTS

Eighty-nine articles were included after a complete database search in the systematic review as per our predefined criteria. Analysis revealed a 5-year overall survival of 33.5% for resection of HCC > 10 cm, 41.7% for BCLC B, 23.3% for BCLC C, and 36.6% for multinodular HCC. Peri-operative mortality ranged from 0 to 6.9%. Studies comparing resection versus TACE for BCLC B/C had a survival of 40% versus 17%, respectively.

CONCLUSION

Our systematic review justifies hepatic resection wherever feasible for hepatocellular carcinomas > 10 cm, BCLC B, BCLC C, and multinodular tumors. In addition, we identified and proposed an algorithm with five poor prognostic criteria in this group of patients who may benefit from adjuvant TACE.

Mortality Outcomes by Fibrosis Stage in Nonalcoholic Fatty Liver Disease: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

Fibrosis is a key determinant of clinical outcomes in nonalcoholic fatty liver disease (NAFLD), but time-dependent risk of mortality has not been reported in previous meta-analyses. We performed an updated time-to-event meta-analysis to provide robust estimates for all-cause and liver-related mortality in biopsy-confirmed NAFLD with comparisons between fibrosis stages.

METHODS

Medline and Embase databases were searched to include cohort studies reporting survival outcomes by fibrosis stage in biopsy-proven NAFLD. Survival estimates were pooled using reconstructed individual participant data. Conventional meta-analysis was conducted to pool adjusted hazard ratios (HRs) using DerSimonian and Laird random effects model.

RESULTS

A total of 14 articles involving 17,301 patients with NAFLD were included. All-cause mortality at 1, 5, and 10 years for stage 0 to 2 fibrosis was 0.1%, 3.3%, and 7.7% vs 0.3%, 20.6%, and 41.5% for stage 4 fibrosis. Compared with stage 0 fibrosis, all-cause mortality increased with fibrosis stage: stage 2; HR, 1.46 (95% confidence interval [CI], 1.08-1.98), stage 3; HR, 1.96 (95% CI, 1.41-2.72), and stage 4; HR, 3.66 (95% CI, 2.65-5.05). Risk for liver-related mortality increased exponentially as fibrosis stage increased: stage 2; HR, 4.07 (95% CI, 1.44-11.5), stage 3; HR, 7.59 (95% CI, 2.80-20.5), and stage 4; HR, 15.1 (95% CI, 5.27-43.4). Stage 3 to 4 fibrosis had a higher all-cause (HR, 3.32) and liver-related mortality (HR, 10.40) compared with stage 0 to 2 fibrosis, whereas stage 4 fibrosis had higher all-cause (HR, 2.67; 95% CI, 1.47-4.83) and liver-related mortality (HR, 2.57; 95% CI, 1.22-5.42) vs stage 3 fibrosis.

CONCLUSIONS

Risk of all-cause and liver-related mortality increases substantially with fibrosis stage. These data have important implications for prognostication and trial design.

Preservation of Mitochondrial Health in Liver Ischemia/Reperfusion Injury

Liver ischemia-reperfusion injury (LIRI) is a major cause of the development of complications in different clinical settings such as liver resection and liver transplantation. Damage arising from LIRI is a major risk factor for early graft rejection and is associated with higher morbidity and mortality after surgery. Although the mechanisms leading to the injury of parenchymal and non-parenchymal liver cells are not yet fully understood, mitochondrial dysfunction is recognized as a hallmark of LIRI that exacerbates cellular injury. Mitochondria play a major role in glucose metabolism, energy production, reactive oxygen species (ROS) signaling, calcium homeostasis and cell death. The diverse roles of mitochondria make it essential to preserve mitochondrial health in order to maintain cellular activity and liver integrity during liver ischemia/reperfusion (I/R). A growing body of studies suggest that protecting mitochondria by regulating mitochondrial biogenesis, fission/fusion and mitophagy during liver I/R ameliorates LIRI. Targeting mitochondria in conditions that exacerbate mitochondrial dysfunction, such as steatosis and aging, has been successful in decreasing their susceptibility to LIRI. Studying mitochondrial dysfunction will help understand the underlying mechanisms of cellular damage during LIRI which is important for the development of new therapeutic strategies aimed at improving patient outcomes. In this review, we highlight the progress made in recent years regarding the role of mitochondria in liver I/R and discuss the impact of liver conditions on LIRI.

Induction of liver transplant immune tolerance in an outbred rat strain model using tacrolimus

BACKGROUND

Orthotopic liver transplantation is the only option for patients with end-stage liver disease and hepatocellular carcinoma. Post-transplant immunosuppressive therapy is important to prevent graft failure. We investigated the effectiveness of tacrolimus (FK506) and their mechanisms for liver transplant immune tolerance in an outbred rat LT model.

RESULTS

To investigate the therapeutic effect of the FK506 on outbred rat LT model, FK506 and postoperative therapy were administered subcutaneously once or twice daily to transplanted rats. Histopathological and immunohistochemical analyses were conducted for all groups. The regulation of inflammatory cytokine signaling in the spleen was analyzed by flow cytometry. FK506 attenuated allograft rejection and increased survival in rat orthotopic liver transplantation models. The FK506-treated group had reduced serum levels of alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase. Furthermore, FK506 decreased the expression of inflammatory cytokines and the activation of pathogenic Th1 and Th17 cells in the liver.

CONCLUSIONS

Taken together, we revealed that FK506 ameliorated strong allograft rejection in outbred liver transplantation model by anti-inflammatory effect and inhibitory peroperty of pathogenic T cells.

Effects of transjugular intrahepatic portosystemic shunt on abdominal muscle mass in patients with decompensated cirrhosis

BACKGROUND

Sarcopenia is a common finding in patients with decompensated cirrhosis without effective therapy. We aimed to examine whether a transjugular portosystemic shunt (TIPS) could improve the abdominal muscle mass assessed by cross-sectional images in patients with decompensated cirrhosis and to investigate the association of imaging-defined sarcopenia with the prognosis of such patients.

METHODS

In this retrospective observational study, we enrolled 25 Decompensated cirrhosis patients aged >20 who received TIPS for the control of variceal bleeding or refractory ascites between April 2008 and April 2021. All of them underwent preoperative computed tomography or magnetic resonance imaging, which was used to determine psoas muscle (PM) and paraspinal muscle (PS) indices at the third lumbar vertebra. First, we compared baseline muscle mass with muscle mass at 6 and 12 months after TIPS placement and analyzed PM- and PS-defined sarcopenia to predict mortality.

RESULTS

Among 25 patients, 20 (80.0%) and 12 (48.0%) had PM- and PS-defined sarcopenia, respectively, at baseline. In total, 16 and 8 patients were followed up for 6 and 12 months, respectively. All imaging-based muscle measurements performed 12 months after TIPS placement were significantly greater than the baseline measurements (all p < 0.05). Unlike patients with PS-defined sarcopenia (p = 0.529), patients with PM-defined sarcopenia had poorer survival than did patients without (p = 0.036).

CONCLUSIONS

PM mass in patients with decompensated cirrhosis may increase by 6 or 12 months after TIPS placement and imply a better prognosis. Patients with preoperative PM-defined sarcopenia may suggest poorer survival.

miR-449a ameliorates acute rejection after liver transplantation via targeting procollagen-lysine1,2-oxoglutarate5-dioxygenase 1 in macrophages

Acute rejection (AR) is an important factor that leads to poor prognosis after liver transplantation (LT). Macrophage M1-polarization is an important mechanism in AR development. MicroRNAs play vital roles in disease regulation; however, their effects on macrophages and AR remain unclear. In this study, rat models of AR were established following LT, and macrophages and peripheral blood mononuclear cells were isolated from rats and humans, respectively. We found miR-449a expression to be significantly reduced in macrophages and peripheral blood mononuclear cells. Overexpression of miR-449a not only inhibited the M1-polarization of macrophages in vitro but also improved the AR of transplant in vivo. The mechanism involved inhibiting the noncanonical nuclear factor-kappaB (NF-κB) pathway. We identified procollagen-lysine1,2-oxoglutarate5-dioxygenase 1 (PLOD1) as a target gene of miR-449a, which could reverse miR-449a's inhibition of macrophage M1-polarization, amelioration of AR, and inhibition of the NF-κB pathway. Overall, miR-449a inhibited the NF-κB pathway in macrophages through PLOD1 and also inhibited the M1-polarization of macrophages, thus attenuating AR after LT. In conclusion, miR-449a and PLOD1 may be new targets for the prevention and mitigation of AR.

Assessing Donor Liver Quality and Restoring Graft Function in the Era of Extended Criteria Donors

Liver transplantation (LT) is the final treatment option for patients with end-stage liver disease. The increasing donor shortage results in the wide usage of grafts from extended criteria donors across the world. Using such grafts is associated with the elevated incidences of post-transplant complications including initial nonfunction and ischemic biliary tract diseases, which significantly reduce recipient survival. Although several clinical factors have been demonstrated to impact donor liver quality, accurate, comprehensive, and effective assessment systems to guide decision-making for organ usage, restoration or discard are lacking. In addition, the development of biochemical technologies and bioinformatic analysis in recent years helps us better understand graft injury during the perioperative period and find potential ways to restore graft function. Moreover, such advances reveal the molecular profiles of grafts or perfusate that are susceptible to poor graft function and provide insight into finding novel biomarkers for graft quality assessment. Focusing on donors and grafts, we updated potential biomarkers in donor blood, liver tissue, or perfusates that predict graft quality following LT, and summarized strategies for restoring graft function in the era of extended criteria donors. In this review, we also discuss the advantages and drawbacks of these potential biomarkers and offer suggestions for future research.

Liver transplantation in gastroenteropancreatic neuroendocrine tumors

Neuroendocrine tumors are part of a heterogeneous group of tumors located in organs such as the gastrointestinal tract (GIT), lungs, thymus, thyroid, and adrenal glands. The most prevalent sites are the small intestine, cecal appendix, and pancreas. More than 50% of these tumors are associated with metastases at the time of diagnosis. Neuroendocrine tumors are classified according to the degree of cell differentiation and the histopathological proliferation index of the lesion. Neuroendocrine tumors can be well differentiated or poorly differentiated. G3 tumors are characterized by Ki-67 expression greater than 20% and can be either well differentiated (G3 NET) or poorly differentiated (G3 NEC). Neuroendocrine carcinoma (NEC G3) is subdivided into small-cell and large-cell types. When neuroendocrine tumors present clinical and compressive symptoms, carcinoid syndrome is evident. Carcinoid syndrome occurs when the tumor produces neuroendocrine mediators that cannot be metabolized by the liver due to either the size of the tumor or their secretion by the liver itself. Several therapeutic strategies have been described for the treatment of metastatic neuroendocrine tumors, including curative or palliative surgical approaches, peptide receptor radionuclide therapy, percutaneous therapy, systemic chemotherapy, and radiotherapy. Liver surgery is the only approach that can offer a cure for metastatic patients. Liver metastases must be completely resected, and in this context, orthotopic liver transplantation has gained prominence for yielding very promising outcomes in selected cases. The aim of this study is to review the literature on OLT as a form of treatment with curative intent for patients with gastroenteropancreatic neuroendocrine tumors with liver metastasis.

The impact of perceived donor liver quality on post-transplant outcome

BACKGROUND

We analysed the impact of perceived liver donor quality on transplant recipient outcomes.

METHODS

this prospective cohort study included all deceased liver donors during 2008-2018 in the Swiss Transplant Cohort Study. Perceived low-quality liver donors were defined when refused for ≥5 top listed recipients or for all recipients in at least one centre before being transplanted. The effect of liver donor quality on relisting or recipient death at 1 week and 1 year after transplantation was analysed using Kaplan-Meier and Cox proportional hazard models. A 1:3 matching was also performed using a recipient score.

RESULTS

Of 973 liver donors, 187 (19.2%) had perceived poor-quality. Males, obesity, donation after circulatory death and alanine aminotransferase values were significantly associated with perceived poor-quality, with no significant effect of the perceived quality on re-listing or death within the first week and first year post-transplant [(aHR) = 1.45, 95% CI: (0.6, 3.5), P = 0.41 and aHR = 1.52 (95% CI 0.98-2.35), P = 0.06], adjusting by recipient age and gender, obesity, diabetes, prior liver transplantation and model for end-stage liver disease (MELD) score. At 1 year, prior liver transplantation and higher MELD score associated with higher risk of re-listing or death.

CONCLUSION

Comparable post-transplant outcomes with different perceived quality liver donors stresses the need to improve donor selection in liver transplantation.

Graft-to-recipient weight ratio exerts nonlinear effects on prognosis by interacting with donor liver macrosteatosis

Aim

To investigate the interactions between the graft-to-recipient weight ratio (GWRWR) and other risk factors responsible for inferior allograft outcomes.

Methods

A total of 362 patients who received liver transplantation (LT) were enrolled. Indicators such as graft/recipient weight and other prognostic factors were collected. Comparisons of indicators and survival analysis were performed in groups categorized by the GWRWR. Interactions of large-for-size grafts (LFSGs) with graft macrosteatosis (MaS) were evaluated in terms of relative excess risk caused by interaction (RERI) and attributable proportion (AP). Cytoscape visualized the role of LFSGs in the risk profile for poor prognosis.

Results

Based on the GWRWR, LT cases can be categorized into three subgroups, standard (1%-2.5%), optimal (2.5%-3.0%), and inferior prognosis (>3.0%). Survival analysis confirmed clear separations in cases categorized by the above-defined limits on the GWRWR (P < 0.05). LFSGs caused inferior prognosis by initiating positive interactions with MaS severity.

Conclusion

The GWRWR exerted nonlinear effects on prognosis in deceased donor LT cases. LFSGs (GWRWR > 3.0%) caused inferior outcomes, while grafts sized within (2.5%-3.0%) had optimal post-transplant prognosis. MaS increased the risk of poor prognosis by exerting positive synergistic effects on LFSGs.

Treatment of acquired transthyretin amyloidosis in domino liver transplantation

BACKGROUND

Domino liver transplantation (DLT) has been commonly used during the last two decades to partly meet the high need for liver transplants. However, the recipients of grafts from patients with noncirrhotic inherited metabolic disorders may ultimately develop metabolic syndrome, and management is usually intricate, being complicated by the underlying initial disorder, other comorbidities, and post-transplantation conditions.

CASE

We report here the management and the outcome in a patient with acquired transthyretin amyloidosis after DLT and significant comorbidities. Final treatment with a transthyretin gene silencing agent, patisiran, was well tolerated and resulted in remission of the aggravating neurological deficits in a follow-up period of 2 years.

CONCLUSIONS

The case presented here supports the concept that patisiran can target the hepatocytes producing the mutated transthyretin in acquired transthyretin amyloidosis, as efficiently as in hereditary transthyretin amyloidosis (hATTR), and can be used to treat patients with transthyretin amyloidosis after DLT.

Novel Benchmark Values for Redo Liver Transplantation: Does the Outcome Justify the Effort?

OBJECTIVE

To define benchmark cutoffs for redo liver transplantation (redo-LT).

BACKGROUND

In the era of organ shortage, redo-LT is frequently discussed in terms of expected poor outcome and wasteful resources. However, there is a lack of benchmark data to reliably evaluate outcomes after redo-LT.

METHODS

We collected data on redo-LT between January 2010 and December 2018 from 22 high-volume transplant centers. Benchmark cases were defined as recipients with model of end stage liver disease (MELD) score ≤25, absence of portal vein thrombosis, no mechanical ventilation at the time of surgery, receiving a graft from a donor after brain death. Also, high-urgent priority and early redo-LT including those for primary nonfunction (PNF) or hepatic artery thrombosis were excluded. Benchmark cutoffs were derived from the 75th percentile of the medians of all benchmark centers.

RESULTS

Of 1110 redo-LT, 373 (34%) cases qualified as benchmark cases. Among these cases, the rate of postoperative complications until discharge was 76%, and increased up to 87% at 1-year, respectively. One-year overall survival rate was excellent with 90%. Benchmark cutoffs included Comprehensive Complication Index CCI ® at 1-year of ≤72, and in-hospital and 1-year mortality rates of ≤13% and ≤15%, respectively. In contrast, patients who received a redo-LT for PNF showed worse outcomes with some values dramatically outside the redo-LT benchmarks.

CONCLUSION

This study shows that redo-LT achieves good outcome when looking at benchmark scenarios. However, this figure changes in high-risk redo-LT, as for example in PNF. This analysis objectifies for the first-time results and efforts for redo-LT and can serve as a basis for discussion about the use of scarce resources.

Current Approaches in the Allocation of Liver Transplantation

In recent decades, important advances have been made in the field of liver transplantation. One of the major problems remaining in this area is the small number of donors. Thus, recent data bring multiple updates of the indications and contraindications of this therapeutic method. The main goal is to increase the number of patients who can benefit from liver transplantation, a therapeutic method that can improve life expectancy and the quality of life of patients with end-stage liver disease. Another goal in the management of these patients is represented by the optimal care of those on the waiting list during that period. A multidisciplinary team approach is necessary to obtain the best results for both the donor and the recipient.

Clinical effects of cluster technology optimization and innovations on laparoscopic splenectomy and azygoportal disconnection: a single-center retrospective study with 500 consecutive cases

BACKGROUND

In Asia, laparoscopic splenectomy and azygoportal disconnection (LSD) has been widely regarded as a preferential treatment modality for cirrhotic portal hypertension (PH). However, LSD involves high surgical risk, technical challenges, and many potential postoperative complications. Technology optimization and innovation in LSD aiming to solve to these difficulties has scarcely been reported. In this retrospective study, we aimed to evaluate the clinical therapeutic effect of our cluster technology optimization and innovation on LSD for PH.

METHODS

From February 2012 to January 2020, 500 patients with cirrhosis who had esophagogastric variceal bleeding and hypersplenism underwent LSD in our department. According to different operation periods, patients were divided into the early-, intermediate-, and late-period groups. We collected information regarding clinical characteristics of all patients as well as their preoperative and postoperative follow-up data.

RESULTS

Compared with the early-period group, operation time and postoperative hospital stay were all significantly different and gradually declined from the intermediate- and late-period groups, respectively (all P &lt; 0.05). Intraoperative blood loss of these three groups was gradually decreased, with significant differences (P &lt; 0.05). The incidences of delayed gastric emptying and diarrhea in the late-period group were all significantly lower than those in the early- and intermediate-period groups, respectively (all P &lt; 0.05). Compared with the early-period group, the incidence of variceal re-bleeding was significantly lower in the intermediate- and late-period groups (all P &lt; 0.05).

CONCLUSION

Our cluster technology optimization and innovation of LSD not only contributed to faster recovery and fewer complications but also enhanced surgical safety for patients. It is worth promoting this approach among patients with EVB and hypersplenism secondary to cirrhotic PH.

Machine learning predicts portal vein thrombosis after splenectomy in patients with portal hypertension: Comparative analysis of three practical models

BACKGROUND

For patients with portal hypertension (PH), portal vein thrombosis (PVT) is a fatal complication after splenectomy. Postoperative platelet elevation is considered the foremost reason for PVT. However, the value of postoperative platelet elevation rate (PPER) in predicting PVT has never been studied.

AIM

To investigate the predictive value of PPER for PVT and establish PPER-based prediction models to early identify individuals at high risk of PVT after splenectomy.

METHODS

We retrospectively reviewed 483 patients with PH related to hepatitis B virus who underwent splenectomy between July 2011 and September 2018, and they were randomized into either a training (n = 338) or a validation (n = 145) cohort. The generalized linear (GL) method, least absolute shrinkage and selection operator (LASSO), and random forest (RF) were used to construct models. The receiver operating characteristic curves (ROC), calibration curve, decision curve analysis (DCA), and clinical impact curve (CIC) were used to evaluate the robustness and clinical practicability of the GL model (GLM), LASSO model (LSM), and RF model (RFM).

RESULTS

Multivariate analysis exhibited that the first and third days for PPER (PPER1, PPER3) were strongly associated with PVT [odds ratio (OR): 1.78, 95% confidence interval (CI): 1.24-2.62, P = 0.002; OR: 1.43, 95%CI: 1.16-1.77, P < 0.001, respectively]. The areas under the ROC curves of the GLM, LSM, and RFM in the training cohort were 0.83 (95%CI: 0.79-0.88), 0.84 (95%CI: 0.79-0.88), and 0.84 (95%CI: 0.79-0.88), respectively; and were 0.77 (95%CI: 0.69-0.85), 0.83 (95%CI: 0.76-0.90), and 0.78 (95%CI: 0.70-0.85) in the validation cohort, respectively. The calibration curves showed satisfactory agreement between prediction by models and actual observation. DCA and CIC indicated that all models conferred high clinical net benefits.

CONCLUSION

PPER1 and PPER3 are effective indicators for postoperative prediction of PVT. We have successfully developed PPER-based practical models to accurately predict PVT, which would conveniently help clinicians rapidly differentiate individuals at high risk of PVT, and thus guide the adoption of timely interventions.

How Old Is Old? An Age-Stratified Analysis of Elderly Liver Donors above 65

In liver transplantation, older donor age is a well-known risk factor for dismal outcomes, especially due to the high susceptibility of older grafts to ischemia-reperfusion injury. However, whether the factors correlating with impaired graft and patient survival following the transplantation of older grafts follow a linear trend among elderly donors remains elusive. In this study, liver transplantations between January 2006 and May 2018 were analyzed retrospectively. Ninety-two recipients of grafts from donors ≥65 years were identified and divided into two groups: (1) ≥65–69 and (2) ≥ 70 years. One-year patient survival was comparable between recipients of grafts from donors ≥65–69 and ≥70 years (78.9% and 70.0%). One-year graft survival was 73.1% (donor ≥65–69) and 62.5% (donor ≥ 70), while multivariate analysis revealed superior one-year graft survival to be associated with a donor age of ≥65–69. No statistically significant differences were found for rates of primary non-function. The influence of donor age on graft and patient survival appears not to have a distinct impact on dismal outcomes in the range of 65–70 years. The impact of old donor age needs to be balanced with other risk factors, as these donors provide grafts that offer a lifesaving graft function.

Relatively Poor Long-term Outcomes Following Liver Transplantation for NASH in the United States

BACKGROUND

Nonalcoholic steatohepatitis (NASH) continues to increase in frequency as an indication for liver transplantation (LT). Data on long-term outcomes for these patients are limited. We aimed to compare long-term patient and graft survival in patients undergoing LT for NASH in the United States to other indications.

METHODS

We analyzed data from the Scientific Registry of Transplant Recipients of adult patients who underwent primary deceased-donor LT from January 1, 2005, to December 31, 2019.

RESULTS

NASH has increased as an indication for LT by 4.5-fold, from 5.2% in 2005 to 23.4% in 2019. Patient (61.2%) and graft survival (59.2%) at 10 y are significantly poorer for NASH than for all other indications other than alcohol. Patients transplanted for NASH have higher body mass index (32.2 versus 27.6) and greater frequency of diabetes (13% versus 11.6%) than any other indication (P < 0.001). Portal vein thrombosis, location in intensive care unit, dialysis, and pre-LT diabetes (P < 0.001 for all) are independently predictive of patient death and graft loss. Body mass index is not predictive. NASH patients undergoing simultaneous liver kidney have markedly worse 10-y patient and graft survival than liver-only (52.3% versus 62.1%). Graft loss was attributed to recurrence of NASH in <1% of patients.

CONCLUSIONS

LT for NASH is associated with relatively poor long-term patient and graft survival when compared with patients transplanted for other indications, NASH patients undergoing simultaneous liver kidney have the worst long-term outcomes.

Small-For-Size Syndrome and Graft Inflow Modulation Techniques in Liver Transplantation

BACKGROUND

Partial liver transplantation has recently been proposed to alleviate organ shortages. However, transplantation of a small-for-size graft is associated with an increased risk of posttransplant hepatic dysfunction, commonly referred to as small-for-size syndrome (SFSS). This review describes the etiology, pathological features, clinical manifestations, and diagnostic criteria of SFSS. Moreover, we summarize strategies to improve graft function, focusing on graft inflow modulation techniques. Finally, unmet needs and future perspectives are discussed.

SUMMARY

In fact, posttransplant SFSS can be attributed to various factors such as preoperative status of the recipients, surgical techniques, donor age, and graft quality, except for graft size. With targeted improvement measures, satisfactory clinical outcomes can be achieved in recipients at increased risk of SFSS. Given the critical role of relative portal hyperperfusion in the pathogenesis of SFSS, various pharmacological and surgical treatments have been established to reduce or partially divert excessive portal inflow, and recipients will benefit from individualized therapeutic regimens after careful evaluation of benefits against potential risks. However, there remain unmet needs for further research into different aspects of SFSS to better understand the correlation between portal hemodynamics and patient outcomes.

KEY MESSAGES

Contemporary transplant surgeons should consider various donor and recipient factors and develop case-specific prevention and treatment strategies to improve graft and recipient survival rates.

Predictors of portal vein thrombosis after laparoscopic splenectomy and azygoportal disconnection in hepatitis B cirrhosis: a prospective study

BACKGROUND

The thrombosis of the main and intrahepatic branches of the portal vein (TMIP) is potentially lethal and deemed a common complication following laparoscopic splenectomy and azygoportal disconnection (LSD) in patients with cirrhosis and portal hypertension (PH). The predictors of TMIP after LSD remain unclear. The aim of this prospective study was to explore the predictive and risk factors for TMIP after LSD in cirrhotic patients with PH caused only by hepatitis B virus.

METHODS

From September 2014 to March 2017, we enrolled 115 patients with hepatitis B cirrhosis and PH who successfully underwent LSD. Patients were subdivided into a TMIP group and a non-TMIP group. Univariate and multivariate logistic regression analysis was conducted on 24 items of demographic and preoperative data, to explore the risk factors of TMIP.

RESULTS

Twenty-nine (25.22%) patients developed TMIP on postoperative day (POD) 7 and 26 (22.81%) patients developed TMIP on POD 30. From POD 7 to POD 30, 12 patients who did not have TMIP at POD 7 were newly diagnosed with TMIP, with portal vein diameter 15.05 ± 2.58 mm. Another 14 patients in whom TMIP had resolved had portal vein diameter 14.02 ± 1.76 mm. Univariate analysis and multivariate logistic regression revealed that portal vein diameter ≥ 13 mm [relative risk (RR) 5.533, 95% confidence interval (CI) 1.222-25.042; P = 0.026] and portal vein diameter ≥ 15 mm (RR 3.636, 95% CI 1.466-9.021; P = 0.005) were significant independent risk factors for TMIP on POD 7 and 30, respectively.

CONCLUSION

Portal vein diameter ≥ 13 mm and ≥ 15 mm were significant independent predictors for TMIP after LSD in patients with hepatitis B cirrhosis and PH on POD 7 and POD 30, respectively.

TRIAL REGISTRATION

We registered our research at https://www.

CLINICALTRIALS

gov/ . The name of research registered is "Warfarin Prevents Portal Vein Thrombosis in Patients After Laparoscopic Splenectomy and Azygoportal Disconnection." The trial registration identifier at clinicaltrials.gov is NCT02247414.