Declining liver utilization for transplantation in the United States and the impact of donation after cardiac death

Safety and use of late-turndown liver allografts to increase rate of transplantation

BACKGROUND

The demand for liver transplants (LT) in the United States far surpasses the availability of allografts. New allocation schemes have resulted in occasional difficulties with allograft placement and increased intraoperative turndowns. We aimed to evaluate the outcomes related to use of late-turndown liver allografts.

METHODS

A review of prospectively collected data of LTs at a single center from July 2019 to July 2023 was performed. Late-turndown placement was defined as an open offer 6 h prior to donation, intraoperative turndown by primary center, or post-cross-clamp turndown.

RESULTS

Of 565 LTs, 25.1% (n = 142) received a late-turndown liver allograft. There were no significant differences in recipient age, gender, BMI, or race (all p > 0.05), but MELD was lower for the late-turndown LT recipient group (median 15 vs 21, p < 0.001). No difference in 30-day, 6-month, or 1-year survival was noted on logistic regression, and no difference in patient or graft survival was noted on Cox proportional hazard regression. Late-turndown utilization increased during the study from 17.2% to 25.8%, and median waitlist time decreased from 77 days in 2019 to 18 days in 2023 (p < 0.001).

CONCLUSION

Use of late-turndown livers has increased and can increase transplant rates without compromising post-transplant outcomes with appropriate selection.

Bile acid and nonalcoholic steatohepatitis: Molecular insights and therapeutic targets

BACKGROUND

Nonalcoholic steatohepatitis (NASH) has been the second most common cause of liver transplantation in the United States. To date, NASH pathogenesis has not been fully elucidated but is multifactorial, involving insulin resistance, obesity, metabolic disorders, diet, dysbiosis, and gene polymorphism. An effective and approved therapy for NASH has also not been established. Bile acid is long known to have physiological detergent function in emulsifying and absorbing lipids and lipid-soluble molecules within the intestinal lumen. With more and more in-depth understandings of bile acid, it has been deemed to be a pivotal signaling molecule, which is capable of regulating lipid and glucose metabolism, liver inflammation, and fibrosis. In recent years, a plethora of studies have delineated that disrupted bile acid homeostasis is intimately correlated with NASH disease severity.

AIMS

The review aims to clarify the role of bile acid in hepatic lipid and glucose metabolism, liver inflammation, as well as liver fibrosis, and discusses the safety and efficacy of some pharmacological agents targeting bile acid and its associated pathways for NASH.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Bile acid has a salutary effect on hepatic metabolic disorders, which can ameliorate liver fat accumulation and insulin resistance mainly through activating Takeda G-protein coupled receptor 5 and farnesoid X receptor. Moreover, bile acid also exerts anti-inflammation and anti-fibrosis properties. Furthermore, bile acid has great potential in nonalcoholic liver disease stratification and treatment of NASH.

Donor Diabetes and Steatosis Affects Recipient Survival Following Liver Transplantation Based on Etiology of Liver Cirrhosis

BACKGROUND

Liver transplantation (LT) offers patients with decompensated cirrhosis the best chance at long-term survival. With the rising prevalence of diabetes, further clarity is needed on the impact of receiving a liver allograft from a donor with diabetes on post-LT outcomes. This study aims to evaluate the impact of donor diabetes on clinical outcomes after LT.

METHODS

This is a retrospective analysis of the United Network for Organ Sharing registry data of LT recipients from January 1, 2000, to December 31, 2021. Outcomes analysis was performed using Cox proportional model for all-cause mortality and graft failure. Confounding was reduced by coarsened exact matching causal inference analysis.

RESULTS

Of 66 960 donors identified, 7178 (10.7%) had diabetes. Trend analysis revealed a longitudinal increase in the prevalence of donor diabetes ( P  < 0.001). Importantly, donor diabetes was associated with increased all-cause mortality (hazard ratio [HR]: 1.13; 95% confidence interval [CI], 1.07-1.19; P  < 0.001) and graft failure (HR: 1.16; 95% CI, 1.11-1.22; P  < 0.001). Receiving donor organ with diabetes reduced graft survival in patients who received LT for nonalcoholic steatohepatitis cirrhosis (HR: 1.26; 95% CI, 1.13-1.41; P  < 0.001) but not other etiologies of cirrhosis.

CONCLUSIONS

Donor diabetes was associated with worse outcomes post-LT, particularly in patients receiving LT for nonalcoholic steatohepatitis cirrhosis. Future studies are needed to better understand the mechanism underlying this association to develop better risk stratification and clinical practice to improve the outcomes of the transplanted patients.

Impact of Median MELD at Transplant Minus 3 National Policy on Quality of Transplanted Livers for Patients With and Without Hepatocellular Carcinoma

BACKGROUND

Patients with hepatocellular carcinoma (HCC) have been overprioritized in the deceased donor liver allocation system. The United Network for Organ Sharing adopted a policy in May 2019 that limited HCC exception points to the median Model for End-Stage Liver Disease at transplant in the listing region minus 3. We hypothesized this policy change would increase the likelihood to transplant marginal quality livers into HCC patients.

METHODS

This was a retrospective cohort study of a national transplant registry, including adult deceased donor liver transplant recipients with and without HCC from May 18, 2017, to May 18, 2019 (prepolicy) to May 19, 2019, to March 1, 2021 (postpolicy). Transplanted livers were considered of marginal quality if they met ≥1 of the following: (1) donation after circulatory death, (2) donor age ≥70, (3) macrosteatosis ≥30% and (4) donor risk index ≥95th percentile. We compared characteristics across policy periods and by HCC status.

RESULTS

A total of 23 164 patients were included (11 339 prepolicy and 11 825 postpolicy), 22.7% of whom received HCC exception points (prepolicy versus postpolicy: 26.1% versus 19.4%; P = 0.03). The percentage of transplanted donor livers meeting marginal quality criteria decreased for non-HCC (17.3% versus 16.0%; P < 0.001) but increased for HCC (17.7% versus 19.4%; P < 0.001) prepolicy versus postpolicy. After adjusting for recipient characteristics, HCC recipients had 28% higher odds of being transplanted with marginal quality liver independent of policy period (odds ratio: 1.28; confidence interval, 1.09-1.50; P < 0.01).

CONCLUSIONS

The median Model for End-Stage Liver Disease at transplant in the listing region minus 3 policy limited exception points and decreased the quality of livers received by HCC patients.

Transplant Candidate Outcomes After Declining a DCD Liver in the United States

BACKGROUND

In the context of the organ shortage, donation after circulatory death (DCD) provides an opportunity to expand the donor pool. Although deceased-donor liver transplantation from DCD donors has expanded, DCD livers continue to be discarded at elevated rates; the use of DCD livers from older donors, or donors with comorbidities, is controversial.

METHODS

Using US registry data from 2009 to 2020, we identified 1564 candidates on whose behalf a DCD liver offer was accepted ("acceptors") and 16 981 candidates on whose behalf the same DCD offers were declined ("decliners"). We characterized outcomes of decliners using a competing risk framework and estimated the survival benefit (adjusted hazard ratio [95% confidence interval]) of accepting DCD livers using Cox regression.

RESULTS

Within 10 y of DCD offer decline, 50.9% of candidates died or were removed from the waitlist before transplantation with any type of allograft. DCD acceptors had lower mortality compared with decliners at 10 y postoffer (35.4% versus 48.9%, P < 0.001). After adjustment for candidate covariates, DCD offer acceptance was associated with a 46% reduction in mortality (0.54 [0.49-0.61]). Acceptors of older (age ≥50), obese (body mass index ≥30), hypertensive, nonlocal, diabetic, and increased risk DCD livers had 44% (0.56 [0.42-0.73]), 40% (0.60 [0.49-0.74]), 48% (0.52 [0.41-0.66]), 46% (0.54 [0.45-0.65]), 32% (0.68 [0.43-1.05]), and 45% (0.55 [0.42-0.72]) lower mortality risk compared with DCD decliners, respectively.

CONCLUSIONS

DCD offer acceptance is associated with considerable long-term survival benefits for liver transplant candidates, even with older DCD donors or donors with comorbidities. Increased recovery and utilization of DCD livers should be encouraged.

The trends in cost associated with liver transplantation in the US: Analysis of weighted hospital data

This study aims to evaluate recent annualized trends in the cost-burden of inpatient hospitalizations associated with liver transplantation (LT) in the US as stratified by patient demographics and medical characteristics. From 2016 to 2019 National Inpatient Sample was used to select patients who underwent LT, from which the weighted charge estimates were derived and converted to admission costs using inflation-adjusted charge-to-cost ratios. The adjusted values were stratified using select patient variables and graphed across the respective years to derive goodness-of-fit for each trend (expressed with R2 and p -values). From 2016 to 2019, the estimated total number of LT-related hospitalizations in the US were 6685, 7075, 7260, and 7815 cases respectively. There was a general increase in the total cost of LT-related hospitalizations over the years: $945.75, $1010.23, $1052.46, and $1143.84 in millions of dollars (0.98, 0.01). Furthermore, positive trends in total cost were observed in the following strata: patients aged 35-49 (0.92, 0.04) and above 65 (0.91, 0.05), Whites (0.99, 0.01), those with congestive heart failure (0.98, 0.01), ≥2 comorbidities (0.97, 0.02), hepatic encephalopathy (0.93, 0.04), and those with private insurance (0.93, 0.04), as well as LT performed in the Northeast (0.94, 0.03), Midwest (0.92, 0.04), and South (0.91, 0.04). Total cost associated with hepatitis C declined significantly (0.94, 0.03). With respect to mean costs, positive trends were observed in the following strata: those with other or cryptogenic liver disease (0.93, 0.03), ≥2 comorbidities (0.96, 0.02), and LT performed in the Northeast region (0.93, 0.04). The number of liver transplants performed in the US, as well as the associated costs, are rising. Given the apparent rising costs in specific patient populations, economic and public health policies must focus on cost containment within these groups to ensure appropriate usage of resources.

The Current Role and Future Applications of Machine Perfusion in Liver Transplantation

The relative paucity of donor livers suitable for transplantation has sparked innovations to preserve and recondition organs to expand the pool of transplantable organs. Currently, machine perfusion techniques have led to the improvement of the quality of marginal livers and to prolonged cold ischemia time and have allowed for the prediction of graft function through the analysis of the organ during perfusion, improving the rate of organ use. In the future, the implementation of organ modulation might expand the scope of machine perfusion beyond its current usage. The aim of this review was to provide an overview of the current clinical use of machine perfusion devices in liver transplantation and to provide a perspective for future clinical use, including therapeutic interventions in perfused donor liver grafts.

Warm Ischemia Induces Spatiotemporal Changes in Lysophosphatidylinositol That Affect Post-Reperfusion Injury in Normal and Steatotic Rat Livers

Warm ischemia-reperfusion injury is a prognostic factor for hepatectomy and liver transplantation. However, its underlying molecular mechanisms are unknown. This study aimed to elucidate these mechanisms and identify the predictive markers of post-reperfusion injury. Rats with normal livers were subjected to 70% hepatic warm ischemia for 15, 30, or 90 min, while those with steatotic livers were subjected to 70% hepatic warm ischemia for only 30 min. The liver and blood were sampled at the end of ischemia and 1, 6, and 24 h after reperfusion. The serum alanine aminotransferase (ALT) activity, Suzuki injury scores, and lipid peroxidation (LPO) products were evaluated. The ALT activity and Suzuki scores increased with ischemic duration and peaked at 1 and 6 h after reperfusion, respectively. Steatotic livers subjected to 30 min ischemia and normal livers subjected to 90 min ischemia showed comparable injury. A similar trend was observed for LPO products. Imaging mass spectrometry of normal livers revealed an increase in lysophosphatidylinositol (LPI (18:0)) and a concomitant decrease in phosphatidylinositol (PI (18:0/20:4)) in Zone 1 (central venous region) with increasing ischemic duration; they returned to their basal values after reperfusion. Similar changes were observed in steatotic livers. Hepatic warm ischemia time-dependent acceleration of PI (18:0/20:4) to LPI (18:0) conversion occurs initially in Zone 1 and is more pronounced in fatty livers. Thus, the LPI (18:0)/PI (18:0/20:4) ratio is a potential predictor of post-reperfusion injury.

Changing liver utilization and discard rates in clinical transplantation in the ex-vivo machine preservation era

Liver transplantation is a well-established treatment for many with end-stage liver disease. Unfortunately, the increasing organ demand has surpassed the donor supply, and approximately 30% of patients die while waiting for a suitable liver. Clinicians are often forced to consider livers of inferior quality to increase organ donation rates, but ultimately, many of those organs end up being discarded. Extensive testing in experimental animals and humans has shown that ex-vivo machine preservation allows for a more objective characterization of the graft outside the body, with particular benefit for suboptimal organs. This review focuses on the history of the implementation of ex-vivo liver machine preservation and how its enactment may modify our current concept of organ acceptability. We provide a brief overview of the major drivers of organ discard (age, ischemia time, steatosis, etc.) and how this technology may ultimately revert such a trend. We also discuss future directions for this technology, including the identification of new markers of injury and repair and the opportunity for other ex-vivo regenerative therapies. Finally, we discuss the value of this technology, considering current and future donor characteristics in the North American population that may result in a significant organ discard.

Risk factors in deceased donor liver transplantation: a single centre experience

Deceased brain-dead donor liver transplantation (LT) is a high-risk intervention. The outcome depends on a large number of modifiable and non-modifiable factors. Objective: to analyze our own experience and identify preoperative and perioperative prognostic factors for poor outcomes in LT. Materials and methods. The study included 301 liver transplants performed between January 2016 and December 2021. Donor and recipient characteristics, intraoperative data, perioperative characteristics including laboratory test data, and the nature and frequency of complications were used for the analysis. Results. The 1-, 3- and 5-year recipient survival rates were 91.8%, 85.1%, and 77.9%, respectively; graft survival rates were 90.4%, 83.7%, and 76.7%, respectively. The most significant predictors of poor outcome of LT on the recipient side were biliary stents (HR 7.203, p < 0.01), acutely decompensated cirrhosis (HR 2.52, p = 0.02); in the postoperative period, non-surgical infectious complications (HR 4.592, p < 0.01) and number of reoperations (HR 4.063, p < 0.01). Donor creatinine level (HR 1.004, p = 0.01, one factor analysis; HR 1.004, p = 0.016, multivariate analysis) was the only reliable prognostic negative factor. Conclusion. LT taking into account established risk factors will improve surgery outcomes and help personalize the therapy for each patient.

Normothermic liver machine perfusion as a dynamic platform for regenerative purposes: What does the future have in store for us?

Liver transplantation has become an immense success; nevertheless, far more recipients are registered on waiting lists than there are available donor livers for transplantation. High-risk, extended criteria donor livers are increasingly used to reduce the discrepancy between organ demand and supply. Especially for high-risk livers, dynamic preservation using machine perfusion can decrease post-transplantation complications and may increase donor liver utilisation by improving graft quality and enabling viability testing before transplantation. To further increase the availability of donor livers suitable for transplantation, new strategies are required that make it possible to use organs that are initially too damaged to be transplanted. With the current progress in experimental liver transplantation research, (long-term) normothermic machine perfusion may be used in the future as a dynamic platform for regenerative medicine approaches, enabling repair and regeneration of injured donor livers. Currently explored therapeutics such as defatting cocktails, RNA interference, senolytics, and stem cell therapy may assist in the repair and/or regeneration of injured livers before transplantation. This review will provide a forecast of the future utility of normothermic machine perfusion in decreasing the imbalance between donor liver demand and supply by enabling the repair and regeneration of damaged donor livers.

Walnut green husk ethanol extract improves gut microbiota and their metabolites associated with NLRP3 in non-alcoholic steatohepatitis

Increasing studies have shown that walnut green husk (WGH) has obvious effects on reducing lipid, resisting oxidation, and protecting the liver. However, the mechanism by which WGH can prevent high-fat diet (HFD)-induced non-alcoholic steatohepatitis (NASH) remains unclear. This study is aimed at investigating the effects of WGH ethanol extract (WGHE) on NLRP3-related biochemical indicators and the diversity and metabolism of gut microbiota in HFD-induced NASH rats. WGHE was administered to HFD-induced NASH rats for 6 weeks. The results showed that WGHE could decrease the levels of blood and liver TC, TG, LDL-C, AST, and ALT and the levels of liver indices, including IL-1β, IL-6, TNF-α, TGF-β, FFA, VLDL, caspase-1, ASC, and NLRP3, while it could increase the levels of HDL-C. The pathological damage to liver tissues was significantly reduced. Moreover, WGHE could reduce the Firmicutes/Bacteroidetes (F/B) ratio and the relative abundances of potentially harmful bacteria, such as Lachnospiraceae and Christensenellaceae, and increase that of potentially beneficial bacteria, such as norank_f__Muribaculaceae. These bacteria were associated with NASH and most of them were significantly associated. A total of 23 gut bacteria and 31 metabolites were significantly altered by HFD, which was reversed by WGHE. The common functional pathways, including lipid metabolism and steroid biosynthesis, were identified through the analysis of KEGG metabolic pathways. In addition, the changes in gut microbiota, such as unclassified_f__Lachnospiraceae, unclassified_g__Blautia, and unclassified_g__Desulfovibrio, were associated with the changes in key intestinal metabolites, such as arachidonoyl amine, xanthine, and 25,26-epoxy-1α-hydroxyvitamin D3. In conclusion, WGHE could mitigate HFD-induced NASH in rats by interfering with the NLRP3-related gut microbiota and their metabolites.

Hyperspectral imaging for quantitative assessment of hepatic steatosis in human liver allografts

INTRODUCTION

In liver transplantation (LT), steatosis is commonly judged to be a risk factor for graft dysfunction, and quantitative assessment of hepatic steatosis remains crucial. Liver biopsy as the gold standard for evaluation of hepatic steatosis has certain drawbacks, i.e. invasiveness, and intra- and inter-observer variability. A non-invasive, quantitative modality could replace liver biopsy and eliminate these disadvantages, but has not yet been evaluated in human LT.

METHODS

We performed a pilot study to evaluate the feasibility and accuracy of hyperspectral imaging (HSI) in the assessment of hepatic steatosis of human liver allografts for transplantation. Thirteen deceased donor liver allografts were included in the study. The degree of steatosis was assessed by means of conventional liver biopsy as well as HSI, performed at the end of backtable preparation, during normothermic machine perfusion (NMP), and after reperfusion in the recipient.

RESULTS

Organ donors were 51 [30-83] years old, and 61.5% were male. Donor body mass index was 24.2 [16.5-38.0] kg/m2. The tissue lipid index (TLI) generated by HSI at the end of back-table preparation correlated significantly with the histopathologically assessed degree of overall hepatic steatosis (R2 = 0.9085, p<0.0001); this was based on a correlation of TLI and microvesicular steatosis (R2 = 0.8120; p<0.0001). There is also a linear relationship between the histopathologically assessed degree of overall steatosis and TLI during NMP (R2 = 0.5646; p = 0.0031) as well as TLI after reperfusion (R2 = 0.6562; p = 0.0008).

CONCLUSION

HSI may safely be applied for accurate assessment of hepatic steatosis in human liver grafts. Certainly, TLI needs further assessment and validation in larger sample sizes. This article is protected by copyright. All rights reserved.

Pretransplant Patient Education in Solid-organ Transplant: A Narrative Review

Education for pretransplant, solid-organ recipient candidates aims to improve knowledge and understanding about the transplant process, outcomes, and potential complications to support informed, shared decision-making to reduce fears and anxieties about transplant, inform expectations, and facilitate adjustment to posttransplant life. In this review, we summarize novel pretransplant initiatives and approaches to educate solid-organ transplant recipient candidates. First, we review approaches that may be common to all solid-organ transplants, then we summarize interventions specific to kidney, liver, lung, and heart transplant. We describe evidence that emphasizes the need for multidisciplinary approaches to transplant education. We also summarize initiatives that consider online (eHealth) and mobile (mHealth) solutions. Finally, we highlight education initiatives that support racialized or otherwise marginalized communities to improve equitable access to solid-organ transplant. A considerable amount of work has been done in solid-organ transplant since the early 2000s with promising results. However, many studies on education for pretransplant recipient candidates involve relatively small samples and nonrandomized designs and focus on short-term surrogate outcomes. Overall, many of these studies have a high risk of bias. Frequently, interventions assessed are not well characterized or they are combined with administrative and data-driven initiatives into multifaceted interventions, which makes it difficult to assess the impact of the education component on outcomes. In the future, well-designed studies rigorously assessing well-defined surrogate and clinical outcomes will be needed to evaluate the impact of many promising initiatives.

Offer Acceptance Patterns for Liver Donors Aged 70 and Older

Despite a documented survival benefit, older liver donor (OLD, age ≥70) graft offers are frequently declined, with utilization worsening over the last decade. To understand how offer acceptance varies by center, we studied 1113 eventually transplanted OLD grafts from 2009 to 2017 using Scientific Registry of Transplant Recipients (SRTR) data and random-intercept multilevel logistic regression. To understand how center-level acceptance of OLD graft offers might be associated with waitlist and posttransplant outcomes, we studied all adult, actively listed, liver-only candidates and recipients during the study period using Poisson regression (transplant rate), competing risks regression (waitlist mortality), and Cox regression (posttransplant mortality). Among 117 centers, OLD offer acceptance ranged from 0 (23 centers) to 95 acceptances, with a median odds ratio of 2.88. Thus, a candidate may be three times as likely to receive an OLD graft simply by listing at a different center. Centers in the highest quartile (Q4) of OLD acceptance (accepted 39% of OLD offers) accepted more nationally shared organs (Q4 versus Q1: 14.1% versus 0.0%, P < 0.001) and had higher annual liver transplant volume (Q4 versus Q1: 80 versus 21, P < 0.001). After adjustment, nationally shared OLD offers (adjusted odds ratio [aOR]: 0.16, 95% confidence interval [CI]: 0.13-0.20) and offers to centers with higher median Model for End-Stage Liver Disease (MELD) at transplant (aOR: 0.74, 95% CI: 0.62-0.87) were less likely to be accepted. OLD offers to centers with higher annual transplant volume were more likely to be accepted (aOR: 1.21, 95% CI: 1.14-1.30). Additionally, candidates listed at centers within the highest quartile of OLD graft offer acceptance had higher deceased donor liver transplantation (DDLT) rates (adjusted incidence rate ratio: 1.45, 95% CI: 1.41-1.50), lower waitlist mortality (adjusted subhazard ratio: 0.76, 95% CI: 0.72-0.76), and similar posttransplant survival (adjusted hazard ratio: 0.93, 95% CI: 0.86-1.01) when compared with those listed at centers in the lowest quartile of OLD graft offer acceptance. The wide variation in OLD offer acceptance supports the need for optimizing the organ offer process and efficiently directing OLD offers to centers more likely to use them.

Long-term Outcomes of Pediatric Living Versus Deceased Donor Liver Transplantation Recipients: A Systematic Review and Meta-analysis

Living donor liver transplantation (LDLT) emerged in the 1980s as a viable alternative to scarce cadaveric organs for pediatric patients. However, pediatric waitlist mortality remains high. Long-term outcomes of living and deceased donor liver transplantation (DDLT) are inconsistently described in the literature. Our aim was to systematically review the safety and efficacy of LDLT after 1 year of transplantation among pediatric patients with all causes of liver failure. We searched the MEDLINE, Medline-in-Process, MEDLINE Epub Ahead of Print, Embase + Embase Classic (OvidSP), and Cochrane (Wiley) from February 1, 1947 to February 26, 2020, without language restrictions. The primary outcomes were patient and graft survival beyond 1 year following transplantation. A meta-analysis of unadjusted and adjusted odds and hazard ratios was performed using a random-effects model. A total of 24 studies with 3677 patients who underwent LDLT and 9098 patients who underwent DDLT were included for analysis. In patients with chronic or combined chronic liver failure and acute liver failure (ALF), 1-year (odds ratio [OR], 0.68; 95% confidence interval [CI], 0.53-0.88), 3-year (OR, 0.73; 95% CI, 0.61-0.89), 5-year (OR, 0.71; 95% CI, 0.57-0.89), and 10-year (OR, 0.42; 95% CI, 0.18-1.00) patient and 1-year (OR, 0.50; 95% CI, 0.35-0.70), 3-year (OR, 0.55; 95% CI, 0.37-0.83), 5-year (OR, 0.5; 95% CI, 0.32-0.76), and 10-year (OR, 0.26; 95% CI, 0.14-0.49) graft survival were consistently better in LDLT recipients compared with those in DDLT recipients. In patients with ALF, no difference was seen between the 2 groups except for 5-year patient survival (OR, 0.60; 95% CI, 0.38-0.95), which favored LDLT. Sensitivity analysis by era showed improved survival in the most recent cohort of patients, consistent with the well-described learning curve for the LDLT technique. LDLT provides superior patient and graft survival outcomes relative to DDLT in pediatric patients with chronic liver failure and ALF. More resources may be needed to develop infrastructures and health care systems to support living liver donation.

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.

A systematic review and meta-analyses of regional perfusion in donation after circulatory death solid organ transplantation

In donation after circulatory death (DCD), (thoraco)abdominal regional perfusion (RP) restores circulation to a region of the body following death declaration. We systematically reviewed outcomes of solid organ transplantation after RP by searching PubMed, Embase, and Cochrane libraries. Eighty-eight articles reporting on outcomes of liver, kidney, pancreas, heart, and lung transplants or donor/organ utilization were identified. Meta-analyses were conducted when possible. Methodological quality was assessed using National Institutes of Health (NIH)-scoring tools. Case reports (13/88), case series (44/88), retrospective cohort studies (35/88), retrospective matched cohort studies (5/88), and case-control studies (2/88) were identified, with overall fair quality. As blood viscosity and rheology change below 20 °C, studies were grouped as hypothermic (HRP, ≤20 °C) or normothermic (NRP, >20 °C) regional perfusion. Data demonstrate that RP is a safe alternative to in situ cold preservation (ISP) in uncontrolled and controlled DCDs. The scarce HRP data are from before 2005. NRP appears to reduce post-transplant complications, especially biliary complications in controlled DCD livers, compared with ISP. Comparisons for kidney and pancreas with ISP are needed but there is no evidence that NRP is detrimental. Additional data on NRP in thoracic organs are needed. Whether RP increases donor or organ utilization needs further research.

Recommendations for Donor and Recipient Selection and Risk Prediction: Working Group Report From the ILTS Consensus Conference in DCD Liver Transplantation

Although the utilization of donation after circulatory death donors (DCDs) for liver transplantation (LT) has increased steadily, much controversy remains, and no common acceptance criteria exist with regard to donor and recipient risk factors and prediction models. A consensus conference was organized by International Liver Transplantation Society on January 31, 2020, in Venice, Italy, to review the current clinical practice worldwide regarding DCD-LT and to develop internationally accepted guidelines. The format of the conference was based on the grade system. International experts in this field were allocated to 6 working groups and prepared evidence-based recommendations to answer-specific questions considering the currently available literature. Working group members and conference attendees served as jury to edit and confirm the final recommendations presented at the end of the conference by each working group separately. This report presents the final statements and recommendations provided by working group 2, covering the entire spectrum of donor and recipient risk factors and prediction models in DCD-LT.

Noninvasive Detection of Ischemic Vascular Damage in a Pig Model of Liver Donation After Circulatory Death

BACKGROUND AND AIMS

Liver graft quality is evaluated by visual inspection prior to transplantation, a process highly dependent on the surgeon's experience. We present an objective, noninvasive, quantitative way of assessing liver quality in real time using Raman spectroscopy, a laser-based tool for analyzing biomolecular composition.

APPROACH AND RESULTS

A porcine model of donation after circulatory death (DCD) with normothermic regional perfusion (NRP) allowed assessment of liver quality premortem, during warm ischemia (WI) and post-NRP. Ten percent of circulating blood volume was removed in half of experiments to simulate blood recovery for DCD heart removal. Left median lobe biopsies were obtained before circulatory arrest, after 45 minutes of WI, and after 2 hours of NRP and analyzed using spontaneous Raman spectroscopy, stimulated Raman spectroscopy (SRS), and staining. Measurements were also taken in situ from the porcine liver using a handheld Raman spectrometer at these time points from left median and right lateral lobes. Raman microspectroscopy detected congestion during WI by measurement of the intrinsic Raman signal of hemoglobin in red blood cells (RBCs), eliminating the need for exogenous labels. Critically, this microvascular damage was not observed during WI when 10% of circulating blood was removed before cardiac arrest. Two hours of NRP effectively cleared RBCs from congested livers. Intact RBCs were visualized rapidly at high resolution using SRS. Optical properties of ischemic livers were significantly different from preischemic and post-NRP livers as measured using a handheld Raman spectrometer.

CONCLUSIONS

Raman spectroscopy is an effective tool for detecting microvascular damage which could assist the decision to use marginal livers for transplantation. Reducing the volume of circulating blood before circulatory arrest in DCD may help reduce microvascular damage.

Consensus statement on normothermic regional perfusion in donation after circulatory death: report from the European Society for Organ Transplantation's Transplant Learning Journey

Normothermic regional perfusion (NRP) in donation after circulatory death (DCD) is a safe alternative to in situ cooling and rapid procurement. An increasing number of countries and centres are performing NRP, a technically and logistically challenging procedure. This consensus document provides evidence-based recommendations on the use of NRP in uncontrolled and controlled DCDs. It also offers minimal ethical, logistical and technical requirements that form the foundation of a safe and effective NRP programme. The present article is based on evidence and opinions formulated by a panel of European experts of Workstream 04 of the Transplantation Learning Journey project, which is part of the European Society for Organ Transplantation.

Comparison of results on the use of extended criteria liver doners for transplants in Espírito Santo

INTRODUCTION

liver Transplantation is currently the treatment of choice for several terminal liver diseases. Despite the increase in performed transplants, the waiting lists continue to increase. In order to expand the supply of organs, transplantation teams have started to use previously rejected livers for transplants because of an increased risk of unfavorable outcomes.

OBJECTIVE

to evaluate the use of livers of expanded criterion donators.

METHODS

retrospective study of medical records. The livers were classified as normal or expanded criteria. The groups were divided in low and high MELD. A multivariate analysis was performed through logistic regression.

RESULTS

there was no statistical difference regarding early, late and global mortality between the groups. Decreased survival was observed in patients with high MELD (higher or equal to 20) when they received grafts from expanded criterion donators. The association between the occurrence of cardiorespiratory arrest and presence of elevated total bilirubin in donators was associated with higher mortality rates in expanded criterion livers.

CONCLUSION

the overall results are similar, but expanded criteria liver donators was associated with higher mortality in patients with high MELD.

Changing Trends in Liver Transplantation: Challenges and Solutions

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

Changing trends of liver transplantation and mortality from non-alcoholic fatty liver disease

The rising tide of non-alcoholic fatty liver disease (NAFLD) associated with the obesity epidemic is a major international health concern. NAFLD is the leading global cause of liver disease with an estimated prevalence of 25% and is the fastest growing indication for liver transplantation (LT). The presence and severity of liver fibrosis is the only histologic predictor of clinical outcomes in this group. NAFLD poses several challenges in the peri-transplant setting including the management of multiple metabolic co-morbidities, post-transplant obesity and cardiovascular risk. However, post-LT outcomes in well-selected NAFLD patients appear similar to non-NAFLD indications, including in the setting of hepatocellular carcinoma (HCC). The rising prevalence of NAFLD may impact potential liver graft donors, which may in-turn adversely affect post-LT outcomes. This review outlines the current epidemiology, natural history and outcomes of NAFLD with a focus on pre- and post-liver transplant settings.

Microsteatosis in Livers From Donation After Circulatory Death Donors Is Associated With Inferior Outcomes Following Liver Transplantation

The acceptable threshold remains unknown for the percentage of macrosteatosis (MaS) and microsteatosis (MiS) to yield optimal outcomes after donation after circulatory death (DCD) liver transplantation (LT). The purpose of this analysis was to determine the impact of donor liver MaS and MiS on DCD LT outcomes. Using the Organ Procurement and Transplantation Network database, we analyzed pretransplant biopsy results from adult, solitary, DCD livers transplanted between January 1, 2006, and December 31, 2017. Kaplan-Meier analysis was used to assess graft and patient survival based on MaS and MiS severity. MiS was divided into the groups MiS ≤10% and >10%. MaS was divided into the groups MaS ≤15% and >15%. Of 7757 recovered DCD livers, 11.4% (n = 885) were biopsied and transplanted. Patients who received DCD livers with MaS >15% had significantly worse patient survival (P < 0.04), and those with MiS >10% demonstrated inferior graft and patient survival (P < 0.02). In multivariate analyses including known risk factors, both MaS >15% and MiS >10% were associated with increased risk of graft failure and patient mortality (P < 0.03). Recipient and donor age >60 years were also associated with increased risk of graft failure and patient death. This analysis demonstrates that MaS >15% and MiS >10% are additional risk factors for graft loss and patient mortality in DCD LT.

The trials and tribulations of liver allocation

Allocation policies are necessary to ensure a fair distribution of a scarce resource. The goal of any liver transplant allocation policy is to achieve the best possible outcomes for the waiting list population, irrespective of the indication for transplant, whilst maximizing organ utilization. Organ allocation for liver transplantation has evolved from simple centre-based approaches driven by local issues, to complex, evidence-based algorithm prioritizing according to need. Despite the rapid evolution of allocation policies, there remain a number of challenges and new approaches are required to ensure transparency and equity on the decision-making process and the best possible outcomes for patients on the waiting list. New ways of modelling, together with novel outcome criteria, will be required to enable a dynamic adaptability of the allocation policies to the ever changing demographics of the donor population and the changing landscape of indications for transplantation.

Portal venous repopulation of decellularised rat liver scaffolds with syngeneic bone marrow stem cells

Liver transplantation is the only life-saving treatment for end-stage liver failure but is limited by the organ shortage and consequences of immunosuppression. Repopulation of decellularised scaffolds with recipient cells provides a theoretical solution, allowing reliable and timely organ sourcing without the need for immunosuppression. Recellularisation of the vasculature of decellularised liver scaffolds was investigated as an essential prerequisite to the survival of other parenchymal components. Liver decellularisation was carried out by portal vein perfusion using a detergent-based solution. Decellularised scaffolds were placed in a sterile perfusion apparatus consisting of a sealed organ chamber, functioning at 37°C in normal atmospheric conditions. The scaffold was perfused via portal vein with culture medium. A total of 10⁷ primary cultured bone marrow stem cells, selected by plastic adherence, were infused into the scaffold, after which repopulated scaffolds were perfused for up to 30 days. The cultured stem cells were assessed for key marker expression using fluorescence-activated cell sorting (FACS), and recellularised scaffolds were analysed by light, electron and immunofluorescence microscopy. Stem cells were engrafted in portal, sinusoidal and hepatic vein compartments, with cell alignment reminiscent of endothelium. Cell surface marker expression altered following engraftment, from haematopoietic to endothelial phenotype, and engrafted cells expressed sinusoidal endothelial endocytic receptors (mannose, Fc and stabilin receptors). These results represent one step towards complete recellularisation of the liver vasculature and progress towards the objective of generating transplantable neo-organs.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Outcomes of endoscopic therapy in donation after cardiac death liver transplant biliary strictures

BACKGROUND

Biliary strictures after donation-after-cardiac-death (DCD) liver transplantation (LT) require multiple endoscopic retrograde cholangiopancreatographies (ERCP). The outcomes of endoscopic dilation and maximal stenting are not well-characterized in this high-risk population.

METHODS

DCD LT recipients who underwent LT and ERCP from 2012-2018 were selected. Anastomotic and non-anastomotic strictures were treated with balloon dilation and maximal stenting. A successful stent-free trial was defined as absence of biochemical, clinical or imaging evidence of strictures on follow-up exceeding 6 months. Adverse events were defined as unplanned admission or inpatient evaluation within 7 days of ERCP.

RESULTS

Forty-nine DCD LT recipients underwent ERCP and 34 patients were diagnosed with strictures (20 anastomotic). Stent-free trial was successful in 27 patients. Adverse events occurred after 20 ERCPs. Patients with anastomotic strictures required fewer stents (1.43 ± 1.37 vs 2.63 ± 1.66; P < 0.001), shorter procedure and fluoroscopy times (34.15 ± 20.9 vs 59.6 ± 30.7 minutes, P < 0.001; 5.99 ± 7.4 vs 14.73 ± 10.74 minutes, P < 0.001), fewer relapses (10% vs 57%, P = 0.003), shorter intervals between initial ERCP and stent-free success (136.9 ± 118.3 vs 399.56 ± 234.7; P = 0.003), and between LT and stent-free success (227.8 ± 171.9 vs 464.1 ± 224.6 days; P = 0.005) compared to non-anastomotic strictures.

CONCLUSION

Endoscopic dilation and maximal stenting resolves biliary strictures in DCD LT recipients with sustained success and relatively few adverse events.

Prevalence and Profile of Discarded Liver Donors in a Tertiary Health Service in Brazil From 2015 to 2018

BACKGROUND

Little has changed in donor management and liver utilization rates in Brazil over the last decade. With a growing demand for liver donations, organ waste is an important obstacle toward better patient care. The study of discarded donors helps to shed light on the possibilities of increasing organ usage, including by using extended criteria donors.

METHODS

We retrospectively analyzed all discarded liver donors in a high-volume Brazilian transplant center from January 2015 to December 2018. Pertinent clinical and laboratorial data were collected from the donors' electronic health records.

RESULTS

In our study period, there were 248 liver harvests, of which 67 (27.0%) were discarded. Most discarded donors were male (65.7%). More than three-quarters of donors were Caucasian (79.1%). Median donor body mass index was 26.27 kg/m², and most discarded donors presented no comorbidities. Donor liver injury tests were abnormal in 56 (83.5%) out of 67 discarded donors. Forty-three (64.1%) donors presented elevated transaminases. Alanine aminotransferase levels were elevated in 35 (52.2%) discarded donors, with a median value of 38 U/L. Half of all discarded livers were due to graft-related issues. Twenty-eight organs (41.79%) presented external pathologic alterations. Organ refusal due to donor clinical and laboratorial condition was reported in 24 cases.

CONCLUSION

It is clear there is a considerable issue of organ waste in Brazil, with the subjective judgment of graft quality and inadequate interpretation of donor's laboratorial exams leading to excessive denial of organs that could be fitted into extended criteria for donation.

Deregulation of the Purine Pathway in Pre-Transplant Liver Biopsies Is Associated with Graft Function and Survival after Transplantation

The current shortage of livers for transplantation has increased the use of marginal organs sourced from donation after circulatory death (DCD). However, these organs have a higher incidence of graft failure, and pre-transplant biomarkers which predict graft function and survival remain limited. Here, we aimed to find biomarkers of liver function before transplantation to allow better clinical evaluation. Matched pre- and post-transplant liver biopsies from DCD (n = 24) and donation after brain death (DBD, n = 70) were collected. Liver biopsies were analysed using mass spectroscopy molecular phenotyping. Discrimination analysis was used to parse metabolites differentiated between the two groups. Five metabolites in the purine pathway were investigated. Of these, the ratios of the levels of four metabolites to those of urate differed between DBD and DCD biopsies at the pre-transplantation stage (q < 0.05). The ratios of Adenosine monophosphate (AMP) and adenine levels to those of urate also differed in biopsies from recipients experiencing early graft function (EGF) (q < 0.05) compared to those of recipients experiencing early allograft dysfunction (EAD). Using random forest, a panel consisting of alanine aminotransferase (ALT) and the ratios of AMP, adenine, and hypoxanthine levels to urate levels predicted EGF with area under the curve (AUC) of 0.84 (95% CI (0.71, 0.97)). Survival analysis revealed that the metabolite classifier could stratify six-year survival outcomes (p = 0.0073). At the pre-transplantation stage, a panel composed of purine metabolites and ALT could improve the prediction of EGF and survival.

Transplant Outcomes of Donation After Circulatory Death Livers Recovered With Versus Without Premortem Heparin Administration

Premortem heparin administration during donation after circulatory death (DCD) organ recovery is thought to optimize liver perfusion. However, premortem heparinization is not universally practiced in the United States and limited data exist regarding its utility. US registry data were accessed between January 1, 2003, and March 10, 2017, and 2 cohorts were ascertained: (1) DCD donor livers recovered for transplantation (n = 5495) and (2) liver-only adult transplant recipients of DCD livers (n = 3754). Exclusions were donor unknown heparin status (n = 40), positive donor hepatitis B surface antigen (n = 4) and hepatitis C virus (n = 120) serologies, and for the outcomes analysis, livers placed outside the United States (n = 10). Discard rates and graft outcomes were examined from cohorts 1 and 2, respectively. Of 5495 DCD livers recovered for transplant, 589 (10.7%) donors did not receive premortem heparin (no heparin) and the remaining 4906 (89.3%) received heparin (heparin). Liver discard was similar between the no heparin (30.6%) and heparin groups (30.8%; P = 0.90). Heparin status was not associated with liver discard on multivariate analysis (adjusted odds ratio, 0.97; 95% confidence interval [CI], 0.80-1.18 P = 0.76). The cumulative probability of overall graft survival was lower in the no heparin group relative to the heparin group (P < 0.05), and this finding persisted on multivariate analysis. No heparin group transplants had an 18% higher hazard of overall graft failure compared with those that received heparin (adjusted hazard ratio, 1.18; 95% CI, 1.01-1.38; P < 0.05). In conclusion, organ recovery heparin administration status was not associated with liver discard. Failure to pretreat organ donors with premortem heparin correlates with worse liver transplant graft survival compared with heparin-treated livers.

Peri-transplant management of nonalcoholic fatty liver disease in liver transplant candidates

The incidence of non-alcoholic fatty liver disease (NAFLD) is rapidly growing, affecting 25% of the world population. Non-alcoholic steatohepatitis (NASH) is the most severe form of NAFLD and affects 1.5% to 6.5% of the world population. Its rising incidence will make end-stage liver disease (ESLD) due to NASH the number one indication for liver transplantation (LT) in the next 10 to 20 years, overtaking Hepatitis C. Patients with NASH also have a high prevalence of associated comorbidities such as type 2 diabetes, obesity, metabolic syndrome, cardiovascular disease, and chronic kidney disease (CKD), which must be adequately managed during the peritransplant period for optimal post-transplant outcomes. The focus of this review article is to provide a comprehensive overview of the unique challenges these patients present in the peritransplant period, which comprises the pre-transplant, intraoperative, and immediate postoperative periods.

Transcriptional changes during hepatic ischemia-reperfusion in the rat

There are few effective targeted strategies to reduce hepatic ischemia-reperfusion (IR) injury, a contributor to poor outcomes in liver transplantation recipients. It has been proposed that IR injury is driven by the generation of reactive oxygen species (ROS). However, recent studies implicate other mediators of the injury response, including mitochondrial metabolic dysfunction. We examined changes in global gene expression after transient hepatic ischemia and at several early reperfusion times to identify potential targets that could be used to protect against IR injury. Male Wistar rats were subjected to 30 minutes of 70% partial warm ischemia followed by 0, 0.5, 2, or 6 hours of reperfusion. RNA was extracted from the reperfused and non-ischemic lobes at each time point for microarray analysis. Identification of differentially expressed genes and pathway analysis were used to characterize IR-induced changes in the hepatic transcriptome. Changes in the reperfused lobes were specific to the various reperfusion times. We made the unexpected observation that many of these changes were also present in tissue from the paired non-ischemic lobes. However, the earliest reperfusion time, 30 minutes, showed a marked increase in the expression of a set of immediate-early genes (c-Fos, c-Jun, Atf3, Egr1) that was exclusive to the reperfused lobe. We interpreted these results as indicating that this early response represented a tissue autonomous response to reperfusion. In contrast, the changes that occurred in both the reperfused and non-ischemic lobes were interpreted as indicating a non-autonomous response resulting from hemodynamic changes and/or circulating factors. These tissue autonomous and non-autonomous responses may serve as targets to ameliorate IR injury.

Transplantation of high-risk donor livers after resuscitation and viability assessment using a combined protocol of oxygenated hypothermic, rewarming and normothermic machine perfusion: study protocol for a prospective, single-arm study (DHOPE-COR-NMP trial)

INTRODUCTION

Extended criteria donor (ECD) livers are increasingly accepted for transplantation in an attempt to reduce the gap between the number of patients on the waiting list and the available number of donor livers. ECD livers; however, carry an increased risk of developing primary non-function (PNF), early allograft dysfunction (EAD) or post-transplant cholangiopathy. Ischaemia-reperfusion injury (IRI) plays an important role in the development of these complications. Machine perfusion reduces IRI and allows for reconditioning and subsequent evaluation of liver grafts. Single or dual hypothermic oxygenated machine perfusion (DHOPE) (4°C-12°C) decreases IRI by resuscitation of mitochondria. Controlled oxygenated rewarming (COR) may further reduce IRI by preventing sudden temperature shifts. Subsequent normothermic machine perfusion (NMP) (37°C) allows for ex situ viability assessment to facilitate the selection of ECD livers with a low risk of PNF, EAD or post-transplant cholangiopathy.

METHODS AND ANALYSIS

This prospective, single-arm study is designed to resuscitate and evaluate initially nationwide declined ECD livers. End-ischaemic DHOPE will be performed for the initial mitochondrial and graft resuscitation, followed by COR of the donor liver to a normothermic temperature. Subsequently, NMP will be continued to assess viability of the liver. Transplantation into eligible recipients will proceed if all predetermined viability criteria are met within the first 150 min of NMP. To facilitate machine perfusion at different temperatures, a perfusion solution containing a haemoglobin-based oxygen carrier will be used. With this protocol, we aim to transplant extra livers. The primary endpoint is graft survival at 3 months after transplantation.

ETHICS AND DISSEMINATION

This protocol was approved by the medical ethical committee of Groningen, METc2016.281 in August 2016 and registered in the Dutch Trial registration number TRIAL REGISTRATION NUMBER: NTR5972, NCT02584283.

Projected increase in obesity and non-alcoholic-steatohepatitis-related liver transplantation waitlist additions in the United States

Nonalcoholic steatohepatitis (NASH) cirrhosis is the fastest growing indication for liver transplantation (LT) in the United States. We aimed to determine the temporal trend behind the rise in obesity and NASH-related additions to the LT waitlist in the United States and make projections for future NASH burden on the LT waitlist. We used data from the Organ Procurement and Transplantation Network database from 2000 to 2014 to obtain the number of NASH-related LT waitlist additions. The obese population in the United States from 2000 to 2014 was estimated using data from the U.S. Census Bureau and the National Health and Nutrition Examination Survey. Based on obesity trends, we established a time lag between obesity prevalence and NASH-related waitlist additions. We used data from the U.S. Census Bureau on population projections from 2016 to 2030 to forecast obesity estimates and NASH-related LT waitlist additions. From 2000 to 2014, the proportion of obese individuals significantly increased 44.9% and the number of NASH-related annual waitlist additions increased from 391 to 1,605. Increase in obesity prevalence was strongly associated with LT waitlist additions 9 years later in derivation and validation cohorts (R² = 0.9). Based on these data, annual NASH-related waitlist additions are anticipated to increase by 55.4% (1,354-2,104) between 2016 and 2030. There is significant regional variation in obesity rates and in the anticipated increase in NASH-related waitlist additions (P < 0.01). Conclusion: We project a marked increase in demand for LT for NASH given population obesity trends. Continued public health efforts to curb obesity prevalence are needed to reduce the projected future burden of NASH. (Hepatology 2017).

Predictors of Biliary Strictures After Liver Transplantation Among Recipients of DCD (Donation After Cardiac Death) Grafts

INTRODUCTION

Biliary strictures are a common complication among donation after cardiac death (DCD) liver transplantation (LT) recipients and may require multiple endoscopic retrograde cholangiopancreatography (ERCP) procedures. We evaluated the risk factors associated with development of biliary strictures in DCD LT recipients.

METHODS

DCD LT recipients who underwent transplantation from 2012 to 2017 were divided into 2 groups: (a) those with anastomotic or non-anastomotic biliary strictures who required ERCP ("stricture group") and (b) those who did not require ERCP or had cholangiograms without evidence of biliary strictures ("non-stricture group"). Clinical data, cholangiograms and laboratory values at day 0 and day 7 after LT were compared between the two groups.

RESULTS

Forty-nine of the 100 DCD LT recipients underwent ERCP. Thirty-four of these 49 LT recipients had evidence of anastomotic or non-anastomotic biliary strictures (stricture group), while the remaining 66 LT recipients comprised the non-stricture group. Donor age was significantly higher in stricture group compared to non-stricture group (49.2 ± 1.8 vs 42.8 ± 1.57 years, respectively; p = 0.01). The stricture group had a significantly higher total bilirubin at day 0 (3.5 ± 0.37 vs 2.6 ± 0.21 mg/dL; p = 0.02) and INR at day 7 (1.24 ± 0.06 vs 1.13 ± 0.01; p = 0.048) compared to the non-stricture group. Multi-variate analysis demonstrated significant association between biliary strictures and total bilirubin at day 0 of LT and age of donor.

CONCLUSION

Biliary strictures occur frequently in DCD LT recipients and may be associated with older age of donor. Hyperbilirubinemia immediately after transplant and higher INR in the first 7 days after transplant may predict subsequent development of biliary strictures.

Assessment of Trends in Transplantation of Liver Grafts From Older Donors and Outcomes in Recipients of Liver Grafts From Older Donors, 2003-2016

Importance

In light of the growing population of older adults in the United States, older donors (aged ≥70 years) represent an expansion of the donor pool; however, their organs are underused. Liver grafts from older donors were historically associated with poor outcomes and higher discard rates, but clinical protocols, organ allocation, and the donor pool have changed in the past 15 years.

Objective

To evaluate trends in demographics, discard rates, and outcomes among older liver donors and transplant recipients of livers from older donors in a large national cohort.

Design, Setting, and Participants

Prospective cohort study of 4127 liver grafts from older donors and 3350 liver-only recipients of older donor grafts and 78 990 liver grafts from younger donors (aged 18-69 years) and 64 907 liver-only recipients of younger donor grafts between January 1, 2003, and December 31, 2016, in the United States. The Scientific Registry of Transplant Recipients, which includes data on all transplant recipients in the United States that are submitted by members of the Organ Procurement and Transplantation Network, was used.

Exposures

Year of liver transplant and age of liver donor.

Main Outcomes and Measures

Odds of graft discard and posttransplant outcomes of all-cause graft loss and mortality.

Results

In this study, 4127 liver grafts from older donors were recovered for liver transplant across the study period (2003-2016); 747 liver grafts from older donors were discarded, and 3350 liver grafts from older donors were used for liver-only recipients. After adjusting for donor characteristics other than age and accounting for Organ Procurement Organization-level variation, liver grafts from older donors were more likely to be discarded compared with liver grafts from younger donors in 2003-2006 (adjusted odds ratio [aOR], 1.97; 95% CI, 1.68-2.31), 2007-2009 (aOR, 2.55; 95% CI, 2.17-3.01), 2010-2013 (aOR, 2.04; 95% CI, 1.68-2.46), and 2013-2016 (aOR, 2.37; 95% CI, 1.96-2.86) (P < .001 for all). Transplants of liver grafts from older donors represented a progressively lower proportion of all adult liver transplants, from 6.0% (n = 258 recipients) in 2003 to 3.2% (n = 211 recipients) in 2016 (P = .001). However, outcomes in recipients of grafts from older donors improved over time, with 40% lower graft loss risk (adjusted hazard ratio, 0.60; 95% CI, 0.53-0.68; P < .001) and 41% lower mortality risk (adjusted hazard ratio, 0.59; 95% CI, 0.52-0.68; P < .001) in 2010 through 2016 vs 2003 through 2009; these results were beyond the general temporal improvements in graft loss (interaction P = .03) and mortality risk (interaction P = .04) among recipients of liver grafts from younger donors.

Conclusions and Relevance

These findings show that from 2003 to 2016, liver graft loss and mortality among recipients of liver grafts from older donors improved; however, liver graft discard from older donors remained increased and the number of transplants performed with liver grafts from older donors decreased. Expansion of the donor pool through broader use of liver grafts from older donors might be reasonable.

Survival advantage for patients accepting the offer of a circulatory death liver transplant

BACKGROUND & AIMS

Donation after circulatory death (DCD) in the UK has tripled in the last decade. However, outcomes following DCD liver transplantation are worse than for donation after brainstem death (DBD) liver transplants. This study examines whether a recipient should accept a "poorer quality" DCD organ or wait longer for a "better" DBD organ.

METHODS

Data were collected on 5,825 patients who were registered on the elective waiting list for a first adult liver-only transplant and 3,949 patients who received a liver-only transplant in the UK between 1 January 2008 and 31 December 2015. Survival following deceased donor liver transplantation performed between 2008 and 2015 was compared by Cox regression modelling to assess the impact on patient survival of accepting a DCD liver compared to deferring for a potential DBD transplant.

RESULTS

A total of 953 (23%) of the 3,949 liver transplantations performed utilised DCD donors. Five-year post-transplant survival was worse following DCD than DBD transplantation (69.1% [DCD] vs. 78.3% [DBD]; p <0.0001: adjusted hazard ratio [HR] 1.65; 95% CI 1.40-1.94). Of the 5,798 patients registered on the transplant list, 1,325 (23%) died or were removed from the list without receiving a transplant. Patients who received DCD livers had a lower risk-adjusted hazard of death than those who remained on the waiting list for a potential DBD organ (adjusted HR 0.55; 95% CI 0.47-0.65). The greatest survival benefit was in those with the most advanced liver disease (adjusted HR 0.19; 95% CI 0.07-0.50).

CONCLUSIONS

Although DCD liver transplantation leads to worse transplant outcomes than DBD transplantation, the individual's survival is enhanced by accepting a DCD offer, particularly for patients with more severe liver disease. DCD liver transplantation improves overall survival for UK listed patients and should be encouraged.

LAY SUMMARY

This study looks at patients who require a liver transplant to save their lives; this liver can be donated by a person who has died either after their heart has stopped (donation after cardiac death [DCD]) or after the brain has been injured and can no longer support life (donation after brainstem death [DBD]). We know that livers donated after brainstem death function better than those after cardiac death, but there are not enough of these livers for everyone, so we wished to help patients decide whether it was better for them to accept an early offer of a DCD liver than waiting longer to receive a "better" liver from a DBD donor. We found that patients were more likely to survive if they accepted the offer of a liver transplant as soon as possible (DCD or DBD), especially if their liver disease was very severe.

Minimizing Risk Associated With Older Liver Donors by Matching to Preferred Recipients: A National Registry and Validation Study

BACKGROUND

Allografts from older liver donors (OLDs), 70 years or older are often discarded for fear of inferior outcomes. We previously identified "preferred recipients" who did not suffer the higher risk of graft loss and mortality associated with OLDs. Preferred recipients were first-time, non-status 1 registrants older than 45 years, body mass index less than 35, indication other than hepatitis C, and cold ischemia time less than 8 hours.

METHODS

We assessed the validity of the preferred recipient construct in a larger, more recent cohort (38 891 patients, 2006-2013). We compared recipients of OLD grafts to recipients of average liver donors (ALDs, age = 40-69) and ideal liver donors (ILDs, age = 18-39) grafts using multilevel Cox regression adjusting for recipient and transplant factors.

RESULTS

The use of OLD grafts in preferred recipients has increased from 2006 to 2013 (P = 0.02). Preferred recipients Model for End-Stage Liver Disease scores ranged 6 to 40. Preferred recipients had similar 5-year all-cause graft loss (ACGL) with OLD versus ALD and ILD grafts (25.4% vs 24.5% and 21.6%). Conversely, nonpreferred recipients had higher 5-year ACGL with OLD versus ALD and ILD grafts (41.4% vs 32.9% and 25.6%). After adjustment, preferred recipients had similar graft loss with OLD versus ALD grafts (hazard ratio [HR], 0.921.081.27; P = 0.3) and ILD grafts (HR, 0.981.161.39, P = 0.09); however, nonpreferred recipients had higher ACGL risk with OLD grafts versus ALD (HR, 1.281.411.56, P < 0.001) and ILD grafts (HR, 1.501.671.86, P < 0.001). Similar trends are seen with mortality.

CONCLUSIONS

Because preferred recipients comprise 43.3% (n = 2916) of the current waitlist and span the full range of Model for End-Stage Liver Disease scores, transplanted OLD allografts could be distributed without added risk of graft loss or mortality.

The impact of post-transplant diabetes mellitus on liver transplant outcomes

BACKGROUND

Post-transplant diabetes mellitus (PTDM) is common after liver transplantation (LT). Yet, how PTDM relates to graft outcomes and survival needs elucidation as more individuals are transplanted for nonalcoholic fatty liver disease (NAFLD).

METHODS

This single-center, retrospective study of adult LT recipients (2003-2016) identified PTDM incidence and associations with graft steatosis, rejection, and post-LT patient survival. Multivariable analysis investigated predictors of PTDM. Kaplan-Meier curves depicted patient survival 5 years post-LT.

RESULTS

Among 415 adult LT recipients, 23% had pre-LT DM and 13% were transplanted for NAFLD. PTDM incidence was 34.7%, 46.9%, and 56.2% and overall survival was 90%, 80.9%, and 71.7% at 1, 3, and 5 years, respectively. Over a third of non-NAFLD patients developed PTDM. Half of PTDM cases developed by 6 months and 75% by 12 months. The PTDM group had more rejection episodes compared to no PTDM (31.9% vs 21.8%, P = 0.055), with trends toward worse patient survival 5 years post-LT (log-rank test P = 0.254). Age was the only significant predictor of PTDM.

CONCLUSIONS

Post-transplant diabetes mellitus occurs rapidly in the post-LT period and is a significant problem for both NAFLD and non-NAFLD LT recipients. Age is a significant risk factor for PTDM. Outcomes trended toward increased rejection and worse survival among PTDM individuals, suggesting the benefit of early strategies targeting glucose control.

Liver Donations and Transplants in the State of Paraná, Brazil

BACKGROUND

The increase in the waiting list for a liver and the high mortality rate of patients with terminal liver disease represent serious public health problems in Brazil.

OBJECTIVE

To analyze donations and liver transplants in the State of Paraná, Brazil.

METHOD

A cross-sectional study was carried out with data from 3931 reports of deaths due to brain death and 8146 solid organ transplants made available by the State Transplant System of Paraná between 2011 and 2016. The data related to donation and liver transplantation were analyzed using descriptive statistics and inference.

RESULTS

A total of 751 (28.9%) liver donations were carried out. Of these, the greatest chance of effectiveness occurred in patients younger than 50 years OR: 1.94 (CI: 1.60-2.34; P < .01) and male OR: 1.27 (CI: 1.06-1.52; P < .01). A total of 720 (8.8%) liver transplants were performed, most of which were funded by the Unified Health System. There was a significant increase in donations and liver transplants over the years.

CONCLUSION

Donor numbers and liver transplants increased in the State but did not meet the need for the waiting list within the analyzed period.

Incidence and Impact of Acute Kidney Injury after Liver Transplantation: A Meta-Analysis

Background: The study’s aim was to summarize the incidence and impacts of post-liver transplant (LTx) acute kidney injury (AKI) on outcomes after LTx. Methods: A literature search was performed using the MEDLINE, EMBASE and Cochrane Databases from inception until December 2018 to identify studies assessing the incidence of AKI (using a standard AKI definition) in adult patients undergoing LTx. Effect estimates from the individual studies were derived and consolidated utilizing random-effect, the generic inverse variance approach of DerSimonian and Laird. The protocol for this systematic review is registered with PROSPERO (no. CRD42018100664). Results: Thirty-eight cohort studies, with a total of 13,422 LTx patients, were enrolled. Overall, the pooled estimated incidence rates of post-LTx AKI and severe AKI requiring renal replacement therapy (RRT) were 40.7% (95% CI: 35.4%–46.2%) and 7.7% (95% CI: 5.1%–11.4%), respectively. Meta-regression showed that the year of study did not significantly affect the incidence of post-LTx AKI (p = 0.81). The pooled estimated in-hospital or 30-day mortality, and 1-year mortality rates of patients with post-LTx AKI were 16.5% (95% CI: 10.8%–24.3%) and 31.1% (95% CI: 22.4%–41.5%), respectively. Post-LTx AKI and severe AKI requiring RRT were associated with significantly higher mortality with pooled ORs of 2.96 (95% CI: 2.32–3.77) and 8.15 (95%CI: 4.52–14.69), respectively. Compared to those without post-LTx AKI, recipients with post-LTx AKI had significantly increased risk of liver graft failure and chronic kidney disease with pooled ORs of 3.76 (95% CI: 1.56–9.03) and 2.35 (95% CI: 1.53–3.61), respectively. Conclusion: The overall estimated incidence rates of post-LTx AKI and severe AKI requiring RRT are 40.8% and 7.0%, respectively. There are significant associations of post-LTx AKI with increased mortality and graft failure after transplantation. Furthermore, the incidence of post-LTx AKI has remained stable over the ten years of the study.

Study protocol for a multicenter randomized controlled trial to compare the efficacy of end-ischemic dual hypothermic oxygenated machine perfusion with static cold storage in preventing non-anastomotic biliary strictures after transplantation of liver grafts donated after circulatory death: DHOPE-DCD trial

BACKGROUND

The major concern in liver transplantation of grafts from donation after circulatory death (DCD) donors remains the high incidence of non-anastomotic biliary strictures (NAS). Machine perfusion has been proposed as an alternative strategy for organ preservation which reduces ischemia-reperfusion injury (IRI). Experimental studies have shown that dual hypothermic oxygenated machine perfusion (DHOPE) is associated with less IRI, improved hepatocellular function, and better preserved mitochondrial and endothelial function compared to conventional static cold storage (SCS). Moreover, DHOPE was safely applied with promising results in a recently performed phase-1 study. The aim of the current study is to determine the efficacy of DHOPE in reducing the incidence of NAS after DCD liver transplantation.

METHODS

This is an international multicenter randomized controlled trial. Adult patients (≥18 yrs. old) undergoing transplantation of a DCD donor liver (Maastricht category III) will be randomized between the intervention and control group. In the intervention group, livers will be subjected to two hours of end-ischemic DHOPE after SCS and before implantation. In the control group, livers will be subjected to care as usual with conventional SCS only. Primary outcome is the incidence of symptomatic NAS diagnosed by a blinded adjudication committee. In all patients, magnetic resonance cholangiography will be obtained at six months after transplantation.

DISCUSSION

DHOPE is associated with reduced IRI of the bile ducts. Whether reduced IRI of the bile ducts leads to lower incidence of NAS after DCD liver transplantation can only be examined in a randomized controlled trial.

TRIAL REGISTRATION

The trial was registered in Clinicaltrials.gov in September 2015 with the identifier NCT02584283 .

Prevalence of Steatosis Hepatis in the Eurotransplant Region: Impact on Graft Acceptance Rates

Due to the shortage of liver allografts and the rising prevalence of fatty liver disease in the general population, steatotic liver grafts are considered for transplantation. This condition is an important risk factor for the outcome after transplantation. We here analyze the characteristics of the donor pool offered to the Charité – Universitätsmedizin Berlin from 2010 to 2016 with respect to liver allograft nonacceptance and steatosis hepatis. Of the 2653 organs offered to our center, 19.9% (n=527) were accepted for transplantation, 58.8% (n=1561) were allocated to other centers, and 21.3% (n = 565) were eventually discarded from transplantation. In parallel to an increase of the incidence of steatosis hepatis in the donor pool from 20% in 2010 to 30% in 2016, the acceptance rates for steatotic organs increased in our center from 22.3% to 51.5% in 2016 (p < 0.001), with the majority (86.9%; p > 0.001) having less than 30% macrovesicular steatosis hepatis. However, by 2016, the number of canceled transplantations due to higher grades of steatosis hepatis had significantly increased from 14.7% (n = 15) to 63.6% (42; p < 0.001). The rising prevalence of steatosis hepatis in the donor pool has led to higher acceptance rates of steatotic allografts. Nonetheless, steatosis hepatis remains a predominant phenomenon in discarded organs necessitating future concepts such as organ reconditioning to increase graft utilization.