Primary non-function is frequently associated with fatty liver allografts and high mortality after re-transplantation

Long-Term Outcomes of Recipients of Liver Transplants from Living Donors Treated with a Very Low-Calorie Diet

The increasing prevalence of steatotic liver disease (SLD) in potential living donors is concerning, as it limits donor's availability amid rising demand. OPTIFAST very low-calorie diet (VLCD), a meal replacement product, effectively reduces weight and hepatic steatosis before transplantation. However, data on the outcomes of recipients of VLCD-treated donors are lacking. We conducted a single-center, retrospective study on 199 living donor liver transplant recipients at Toronto General Hospital, Canada, between January 2015 and January 2020. We compared the 1-year posttransplant outcomes between recipients who received organs from donors treated with VLCD (N = 34) for either weight loss or steatosis reduction, with those who did not require treatment (N = 165). Our analysis revealed no statistically significant differences in the rates of postoperative complications (23% vs 32.4%, p=0.3) or intensive care unit stays (70.9% vs 70.6%, p=1) between recipients of non-VLCD and VLCD grafts. Following adjusted multivariate logistic regression, receipt of VLCD grafts was not associated with increased hospital length of stay. In addition, one-year mortality did not differ between the two groups (4.2% non-VLCD recipients vs 2.9% VLCD recipients, p=0.6). OPTIFAST VLCD treatment for liver donors demonstrates positive and safe outcomes in recipients, expanding the pool of potential living donors for increased organ availability.

Dysfunctional Cori and Krebs cycle and inhibition of lactate transporters constitute a mechanism of primary nonfunction of fatty liver allografts

Orthotopic liver transplantation (OLT) is a lifesaving procedure. However, grafts may fail due to primary nonfunction (PNF). In the past, we demonstrated PNFs to be mainly associated with fatty allografts, and given its unpredictable nature, the development of a disease model is urgently needed. In an effort to investigate mechanism of fatty allograft-associated PNFs, we induced fatty liver disease in donor animals by feeding rats a diet deficient in methionine and choline (MCD). We performed OLT with allografts of different grades of hepatic steatosis and compared the results to healthy ones. We assessed liver function by considering serum biochemistries, and investigated genome wide responses following OLT of healthy and fatty allograft-associated PNFs. Furthermore, we performed immunohistochemistry to evaluate markers of oxidative stress and reperfusion injury, inflammation, glycolysis and gluconeogenesis, lactate transport, and its utilization as part of the Cori cycle. Strikingly, PNFs are strictly lipid content dependent. Nonetheless, a fat content of ≤17% and an increase in the size of hepatocytes of ≤11% (ballooning) greatly improved outcome of OLTs and the hepatic microcirculation. Mechanistically, PNFs arise from a dysfunctional Cori cycle with complete ablation of the lactate transporter SLC16A1. Thus, lipid-laden hepatocytes fail to perform gluconeogenesis via lactate reutilization, and the resultant hyperlactatemia and lactic acidosis causes cardiac arrhythmogenicity and death. Furthermore, the genomic and immunohistochemistry investigations underscore a dysfunctional Krebs cycle with impaired energy metabolism in lipid-burdened mitochondria. Together, we show fatty allografts to be highly vulnerable towards ischemia/reperfusion-injury, and stabilizing the Cori cycle is of critical importance to avert PNFs.

Has the risk of liver re-transplantation improved over the two decades?

BACKGROUND

Despite advancements in liver transplantation (LT) over the past two decades, liver re-transplantation (re-LT) presents challenges. This study aimed to assess improvements in re-LT outcomes and contributing factors.

METHODS

Data from the United Network for Organ Sharing database (2002-2021) were analyzed, with recipients categorized into four-year intervals. Trends in re-LT characteristics and postoperative outcomes were evaluated.

RESULTS

Of 128,462 LT patients, 7254 received re-LT. Graft survival (GS) for re-LT improved (91.3%, 82.1%, and 70.8% at 30 days, 1 year, and 3 years post-LT from 2018 to 2021). However, hazard ratios (HRs) for GS remained elevated compared to marginal donors including donors after circulatory death (DCD), although the difference in HRs decreased in long-term GS. Changes in re-LT causes included a reduction in hepatitis C recurrence and an increase in graft failure post-primary LT involving DCD. Trends identified included recent decreased cold ischemic time (CIT) and increased distance from donor hospital in re-LT group. Meanwhile, DCD cohort exhibited less significant increase in distance and more marked decrease in CIT. The shortest CIT was recorded in urgent re-LT group. The highest Model for End-Stage Liver Disease score was observed in urgent re-LT group, while the lowest was recorded in DCD group. Analysis revealed shorter time interval between previous LT and re-listing, leading to worse outcomes, and varying primary graft failure causes influencing overall survival post-re-LT.

DISCUSSION

While short-term re-LT outcomes improved, challenges persist compared to DCD. Further enhancements are required, with ongoing research focusing on optimizing risk stratification models and allocation systems for better LT outcomes.

Low C-reactive Protein and Urea Distinguish Primary Nonfunction From Early Allograft Dysfunction Within 48 Hours of Liver Transplantation

Primary nonfunction (PNF) is a life-threatening complication of liver transplantation (LT), but in the early postoperative period, it can be difficult to differentiate from early allograft dysfunction (EAD). The aim of this study was to determine if serum biomarkers can distinguish PNF from EAD in the initial 48 h following LT.

Materials and Methods

A retrospective study of adult patients that underwent LT between January 2010 and April 2020 was performed. Clinical parameters, absolute values and trends of C-reactive protein (CRP), blood urea, creatinine, liver function tests, platelets, and international normalized ratio in the initial 48 h after LT were compared between the EAD and PNF groups.

Results

There were 1937 eligible LTs, with PNF and EAD occurring in 38 (2%) and 503 (26%) patients, respectively. A low serum CRP and urea were associated with PNF. CRP was able to differentiate between the PNF and EAD on postoperative day (POD)1 (20 versus 43 mg/L; P < 0.001) and POD2 (24 versus 77; P < 0.001). The area under the receiver operating characteristic curve (AUROC) of POD2 CRP was 0.770 (95% confidence interval [CI] 0.645-0.895). The urea value on POD2 (5.05 versus 9.0 mmol/L; P = 0.002) and trend of POD2:1 ratio (0.71 versus 1.32 mmol/L; P < 0.001) were significantly different between the groups. The AUROC of the change in urea from POD1 to 2 was 0.765 (95% CI 0.645-0.885). Aspartate transaminase was significantly different between the groups, with an AUROC of 0.884 (95% CI 0.753-1.00) on POD2.

Discussion

The biochemical profile immediately following LT can distinguish PNF from EAD; CRP, urea, and aspartate transaminase are more effective than ALT and bilirubin in distinguishing PNF from EAD in the initial postoperative 48 h. Clinicians should consider the values of these markers when making treatment decisions.

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.

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.

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

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

Primary Nonfunction and Early Allograft Dysfunction after Liver Transplantation

BACKGROUND

Despite continuous progress in the field of liver transplantation, considerable proportion of patients still suffer from the postoperative graft dysfunction. Clinically, it presents as early allograft dysfunction (EAD), and its more severe form defined as primary nonfunction (PNF). Posttransplant liver dysfunction translates into significantly worse treatment outcomes.

SUMMARY

Both entities are multifactorial, with donor (graft), recipient, and procedure-related factors playing the key roles. Ischemia-reperfusion injury is a major driver of their development. So far, various noninvasive (pharmacological) and invasive strategies have been tested to mitigate its negative effects. This article pre-sents the current approach to diagnosis, prediction, and management of EAD and PNF.

KEY MESSAGES

Different pharmacological interventions may be considered to improve graft function after liver transplantation. Machine perfusion seems to be the most effective method at the moment.

Primary Nonfunction of the Liver Allograft

Severe allograft dysfunction, as opposed to the expected immediate function, following liver transplantation is a major complication, and the clinical manifestations of such that lead to either immediate retransplant or death are the catastrophic end of the spectrum. Primary nonfunction (PNF) has declined in incidence over the years, yet the impact on patient and healthcare teams, and the burden on the organ pool in case of the need for retransplant should not be underestimated. There is no universal test to define the diagnosis of PNF, and current criteria are based on various biochemical parameters surrogate of liver function; moreover, a disparity remains within different healthcare systems on selecting candidates eligible for urgent retransplantation. The impact on PNF from traditionally accepted risk factors has changed somewhat, mainly driven by the rising demand for organs, combined with the concerted approach by clinicians on the in-depth understanding of PNF, optimal graft recipient selection, mitigation of the clinical environment in which a marginal graft is reperfused, and postoperative management. Regardless of the mode, available data suggest machine perfusion strategies help reduce the incidence further but do not completely avert the risk of PNF. The mainstay of management relies on identifying severe allograft dysfunction at a very early stage and aggressive management, while excluding other identifiable causes that mimic severe organ dysfunction. This approach may help salvage some grafts by preventing total graft failure and also maintaining a patient in an optimal physiological state if retransplantation is considered the ultimate patient salvage strategy.

Controlled attenuation parameter measured using transient elastography for the noninvasive assessment of macrovesicular steatosis in potential living liver donors

PURPOSE

This study aimed to determine the diagnostic performance of the controlled attenuation parameter (CAP) measured using transient elastography (TE) for assessing macrovesicular steatosis (MaS) in potential living liver donors using same-day biopsy as a reference standard.

METHODS

This retrospective study included 204 living liver donor candidates who underwent TE and liver biopsy on the same day between July 2013 and June 2014. The histologic degree of MaS was determined. The area under the receiver operating characteristic curve (AUROC) was used to evaluate the performance of CAP for diagnosing MaS of >10%, and the optimal cutoff value was identified using the maximal Youden index.

RESULTS

Based on liver biopsy, 185 subjects had MaS of ≤10% and 19 had MaS of >10%. The CAP value was significantly correlated with the percentage of MaS on liver biopsy (r=0.635, P<0.001), and the median CAP value was significantly higher in subjects with MaS of >10% than in those with MaS of ≤10% (300 dB/m vs. 209 dB/m, P<0.001). The AUROC for diagnosing MaS of >10% by CAP was 0.938 (95% confidence interval, 0.896 to 0.967), and a CAP of >259 dB/m yielded a sensitivity of 84.2% and a specificity of 92.4%.

CONCLUSION

The CAP measured using TE was significantly correlated with MaS and accurately detected substantial MaS in potential living liver donors. The CAP is a promising tool for the noninvasive diagnosis of MaS and may be used to screen unsuitable living liver donor candidates.

Moderately Macrosteatotic Livers Have Acceptable Long-Term Outcomes but Higher Risk of Immediate Mortality

BACKGROUND AND AIMS

Liver transplantation is the most effective treatment for end-stage liver disease (ESLD). Whether moderately macrosteatotic livers (30%-60%) represent a risk for worsened graft function is controversial. The uncertainty, in large part, is owing to the heterogeneous steatosis grading. Our aim was to determine the short- and long-term outcomes of moderately macrosteatotic allografts that were graded according to a standardized institutional protocol.

METHODS

We performed a retrospective analysis of transplants performed between 1994 and 2014. All patients with allografts biopsied pretransplantation were included. Relevant donor and recipient variable were recorded. Moderately macrosteatotic livers were compared with mildly macrosteatotic and nonsteatotic livers. Primary outcomes of interest were patient survival at 90 days, 1 year, and 5 years. Cox regression analyses were carried out to compare survival between the 2 groups.

RESULTS

We compared 65 allografts with moderate macrosteatosis and 810 with no or mild macrosteatosis. Patients with moderately macrosteatotic allografts were 2.69 times as likely to die within the first 90 days after transplant (75.1% vs 91.6% survival) after adjusting for donor age, donor race, recipient age, recipient race, recipient body mass index, recipient diabetes, presence of hepatocellular carcinoma, days on waitlist, Model for End-Stage Liver Disease (MELD) score at transplantation, cold ischemia time. However, for recipients who survive 90 days, moderately macrosteatotic allografts had comparable long-term survival.

CONCLUSION

Our study shows that moderate macrosteatosis is a strong predictor of early but not late mortality. Further studies are needed to distinguish the specific cohort of patients for whom moderately macrosteatotic allografts will lead to acceptable outcomes.

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

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Detection of early allograft dysfunction at 30 min of reperfusion in liver transplantation: An intraoperative diagnostic tool with real time assessment of graft function

INTRODUCTION

During the anhepatic phase of liver transplantation (LT), fibrinolytic activity increases, since the liver clears tissue plasminogen activator (tPA). We hypothesize that patients who fail to reduce fibrinolytic activity following graft reperfusion will have an increased rate of early allograft dysfunction (EAD).

METHODS

Assessment of fibrinolysis in liver transplant recipients was quantified with thrombelastography (TEG) LY30. Changes in LY30 were assessed after graft reperfusion. The 30-min post-reperfusion LY30 was subtracted from the anhepatic LY30 quantifying fibrinolytic changes (delta-LY30).

RESULTS

Seventy-three primary LT patients were included in the analysis. Receiver operating characteristic curve (ROC) analysis identified an inflection point of delta-LY30-5.3% as a risk factor for EAD. EAD occurred in 44% of these patients compared to 5% in high delta-LY30 (p = 0.002).

CONCLUSION

LT recipients that develop hyperfibrinolysis who fail to reduce fibrinolytic activity 30 min after graft reperfusion had an EAD rate 8-fold higher than patients who had a large reduction in LY30 following reperfusion.

Rescue Hepatectomy and Anhepatic Phase Management After Primary Nonfunction in a Liver Transplant

Primary nonfunction is a rare but lethal complication that occurs in a small number of liver transplants. When primary nonfunction occurs, the only definite treatment is retransplant; however, another liver might not be readily available at that time. Hence, a surgeon should be aware of the various options available at hand for patient care during the time interval between the primary nonfunction and retransplant. Here, we describe the management strategy that was devised to take care of an unstable anhepatic patient in the intensive care unit, care of the patient during anhepatic phase, and successful outcome with a second liver transplant. Our index patient was a recipient of a liver donated after cardiac death. While in the operating room, after reperfusion of the liver, the patient had right heart dysfunction leading to hemodynamic instability and congestion of the liver, which culminated in primary nonfunction. Graft hepatectomy had to be done on postoperative day 1 because of deteriorating condition of the patient, and the patient was maintained in anhepatic phase in the intensive care unit for 27 hours.

Tissue Inhibitor of Metalloproteinase 3 Deficiency Disrupts the Hepatocyte E-Cadherin/β-Catenin Complex and Induces Cell Death in Liver Ischemia/Reperfusion Injury

Tissue inhibitor of metalloproteinase (TIMP) 3 is a naturally occurring inhibitor of a broad range of proteases, with key roles in extracellular matrix turnover and in the pathogenesis of various diseases. In this study, we investigated the response of mice lacking TIMP3 (TIMP3-/-) to hepatic ischemia/reperfusion injury (IRI). We report here that TIMP3-/- mice showed an enhanced inflammatory response, exacerbated organ damage, and further impaired liver function after IRI when compared with their wild-type littermates. Loss of TIMP3 led to the cleavage and shedding of E-cadherin during hepatic IRI; the full-length 120-kDa E-cadherin and the ratio of 38-kDa C-terminal fragment/120-kDa E-cadherin were decreased and increased, respectively, in TIMP3-/- livers after IRI. Moreover, GI254023X, a potent inhibitor of a disintegrin and metalloprotease (ADAM) 10, was capable of partially rescuing the expression of E-cadherin in the TIMP3-null hepatocytes. The proteolysis of E-cadherin in the TIMP3-/- livers was also linked to the loss of β-catenin from the hepatocyte membranes and to an increased susceptibility to apoptosis after liver IRI. In a similar fashion, depression of the E-cadherin/β-catenin complex mediated by TIMP3 deletion and knockdown of β-catenin by small interfering RNA were both capable of inducing caspase activation in isolated hepatocytes subjected to H₂ O₂ oxidative stress. Hence, these results support a protective role for TIMP3 expression in sheltering the hepatocyte E-cadherin/β-catenin complex from proteolytic processing and inhibiting apoptosis after hepatic IRI.

Conceptual changes in small-for-size graft and small-for-size syndrome in living donor liver transplantation

Early series in living donor liver transplantation (LDLT) in adults demonstrated a lower safe limit of graft volume standard liver volume ratio 25%–45%. A subsequent worldwide large LDLT series proposed a 0.8 graft recipient weight ratio (GRWR) to define small-for-size graft (SFSG) in adult LDLT. Thereafter, researchers identified innate and inevitable factors including changes in liver volume during imaging studies and graft shrinkage due to perfusion solution. Although the definition of small-for-size syndrome (SFSS) advocated in the 2000s was mainly based on prolonged cholestasis and ascites output, the term SFSS was inadequate to describe clinical manifestations possibly caused by multiple factors. Thus, the term “early allograft dysfunction (EAD),” characterized by total bilirubin >10 mg/dL or coagulopathy with international normalized ratio >1.6 on day 7, has become prevalent to describe graft dysfunction including SFSS after LDLT. Although various efforts have been made to overcome EAD in LDLT, graft selection to maintain an expected GRWR >0.8 and full venous drainage, as well as inflow modulation using splenic artery ligation, have become standard in recent LDLT.

[High donor age for liver transplantation : Tackling organ scarcity in Germany]

BACKGROUND

Liver transplantation is the only curative treatment option for patients with end-stage liver disease; however, the 40% decline of available organ donors in recent years in Germany necessitates the optimization of available resources and possibly extending the criteria to older donors.

MATERIAL AND METHODS

All 2652 livers made available to the Charité Universitätsmedizin Berlin from 2010 to 2016 were retrospectively analyzed and the clinical outcome of 526 liver transplantations during this time frame were evaluated.

RESULTS

The median age of donors of transplanted organs increased from 49.3 years in 2010 to 57.3 years in 2016 (p = 0.02). Organs from donors ≥65 years were more frequently discarded than organs from younger donors (n = 344, 18.4% vs. n = 220, 28.1%; p = 0.005). Moreover, the older donors had higher rates of diabetes mellitus and hepatic steatosis. Organs from older donors had a higher donor risk index (2.8 vs. 2.2; p < 0.001) and were transplanted more often in patients with preserved liver function and hepatocellular carcinoma and liver cirrhosis (n = 121, 74.7% of indications). The 3‑year survival after liver transplantation from donors ≥65 and ≥80 years old was not significantly reduced in comparison to younger donors; however, there was an increased retransplantation rate (28.6%; p = 0.005) after transplantation of organs from donors ≥80 years old.

CONCLUSION

Despite conservative organ acceptance there were higher rates of retransplantation after transplantation from very old donors. In the light of an increasing scarcity of suitable organs this mandates caution and highlights the need for adequate assessment instruments for marginal donor organs before transplantation.

Graft Risk Index After Liver Transplant: Internal and External Validation of a New Spanish Indicator

OBJECTIVES

Scarcity of liver grafts has led to the use of marginal donors, consequently increasing the number of complications posttransplant. To prevent this situation, several indicators have been developed. However, important differences remain among countries. Here, we compared an early-risk liver transplant indicator based on the Spanish Liver Transplant Registry, called the Graft Risk Index, versus the US donor risk index and the Eurotransplant donor risk index.

MATERIALS AND METHODS

The new indicator was based on prospectively collected data from 600 adult liver transplants performed in our center. We considered 2 events to compare the indexes: graft survival and rejection-free graft survival, with Cox proportional regression for analyses. Power to predict graft survival was evaluated by calculating the receiver operating characteristic area under the curve.

RESULTS

We found no differences between the US and Eurotransplant donor risk indexes in prediction of patients with and without early graft failure. With regard to early survival, only the Graft Risk Index allowed better survival discrimination, in which survival progressively decreased with values ≥ 3 (with probability of graft survival at 1 month of 68%; 95% confidence interval, 46.2-82.5). This increase in risk was significant compared with the standard group (hazard ratio of 10.15; 95% confidence interval, C 3.91- 26.32; P < .001). We calculated powers of prediction of 0.52 (95% confidence interval, 0.43-0.62), 0.54 (95% confidence interval, 0.45-0.65), and 0.69 (95% confidence interval, 0.61-0.77) for donor risk index, Eurotransplant donor risk index, and early Graft Risk Index, respectively.

CONCLUSIONS

Neither the US donor risk index nor the Eurotransplant donor risk index was valid for our Spanish liver donation and transplant program. Therefore, an indicator to predict posttransplant graft survival that is adapted to our environment is necessary. This national Graft Risk Index can be a useful tool to optimize donor-recipient matching.

Systematic Evaluation of the Safety Threshold for Allograft Macrovesicular Steatosis in Cadaveric Liver Transplantation

Background: Currently, 30% macrovesicular steatosis (MaS) content is usually assigned empirically as the boundary between “use” and “refuse” a donor liver for liver transplantation (LT); however, this cut-off is questionable due to the lack of systemic evidence of the efficiency relative to prognosis prediction. Clinicians have tried to identify the threshold for optimized utilization of marginal steatotic allografts, but controversy exists among different studies.

Aim: Our study aimed to systematically determine an acceptable donor MaS content cut-off without incurring extra risk in liver transplantation, using meta-analysis.

Methods: The relevant literature reporting the relationship between MaS content and post-transplant mortality/morbidity was searched and retrieved in Pubmed, Embase, and ISI Web of Science.

Results: Nine studies were enrolled into the final analysis. A categorical comparison revealed that patients who received allografts with moderate steatosis (MaS content >30%) had significantly higher risks of graft failure/dysfunction, but not of mortality. Dose-response analysis showed that donor MaS content affected the graft failure/dysfunction in a non-linear relationship. Risks associated with MaS content in terms of poorer outcomes were independent of other risk covariates for liver transplantation. A non-significant increase in risk of inferior post-transplant outcomes was observed in patients who received allografts with a MaS content <35%. The risks of post-transplant graft failure and dysfunction increased with severe donor MaS content infiltration, without a consistent relationship.

Conclusions: The threshold of allograft MaS content can be safely extended to 35% without additional risk burden on post-transplant inferior outcomes. Clarification on “the effects of stratification” for MaS content can provide theoretical evidence for further optimal utilization of marginal steatotic allografts in liver transplantation.

Evaluation of a micro-spectrometer for the real-time assessment of liver graft with mild-to-moderate macrosteatosis: A proof of concept study

BACKGROUND & AIMS

Liver macrosteatosis (MS) is a major predictor of graft dysfunction after transplantation. However, frozen section techniques to quantify steatosis are often unavailable in the context of procurements, and the findings of preoperative imaging techniques correlate poorly with those of permanent sections, so that the surgeon is ultimately responsible for the decision. Our aim was to assess the accuracy of a non-invasive pocket-sized micro-spectrometer (PSM) for the real-time estimation of MS.

METHODS

We prospectively evaluated a commercial PSM by scanning the liver capsule. A double pathological quantification of MS was performed on permanent sections. Initial calibration (training cohort) was performed on 35 livers (MS ≤60%) and an algorithm was created to correlate the estimated (PSM) and known (pathological) MS values. A second assessment (validation cohort) was then performed on 154 grafts.

RESULTS

Our algorithm achieved a coefficient of determination R2 = 0.81. Its validation on the second cohort demonstrated a Lin's concordance coefficient of 0.78. Accuracy reached 0.91%, with reproducibility of 86.3%. The sensitivity, specificity, positive and negative predictive values for MS ≥30% were 66.7%, 100%, 100% and 98%, respectively. The PSM could predict the absence (<30%)/presence (≥30%) of MS with a kappa coefficient of 0.79. Neither graft weight nor height, donor body mass index nor the CT-scan liver-to-spleen attenuation ratio could accurately predict MS.

CONCLUSION

We demonstrated that a PSM can reliably and reproducibly assess mild-to-moderate MS. Its low cost and the immediacy of results may offer considerable added-value decision support for surgeons. This tool could avoid the detrimental and prolonged ischaemia caused by the pathological examination of (potentially) marginal grafts. This device now needs to be assessed in the context of a large-scale multicentre study.

LAY SUMMARY

Macro-vacuolar liver steatosis is a major prognostic factor for outcomes after liver transplantation. However, it is often difficult for logistical reasons to get this estimation during procurement. Therefore, we developed an algorithm for a commercial, portable and affordable spectrometer to accurately estimate this content in a real-time fashion. This device could be of great interest for clinical decision-making to accept or discard a potential human liver graft.

Assessment of Liver Graft Steatosis: Where Do We Stand?

The growing number of patients on waiting lists for liver transplantation and the shortage of organs have forced many centers to adopt extended criteria for graft selection, moving the limit of acceptance for marginal livers. Steatotic grafts that were, in the past, considered strictly unacceptable for transplantation because of the high risk of early nonfunction are now considered as a potential resource for organ implementation. Several methods to diagnose, measure, classify, and stage steatosis exist, but none can be considered qualitatively and quantitatively "the ideal method" to date. Clinical, biological, and imaging data can be very helpful to estimate graft steatosis, but histology still remains the gold standard. There is an increasing need for rapid and reliable tools to assess graft steatosis. Herein, we present a comprehensive review of the approaches that are currently used to quantify steatosis in liver grafts.

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.

Graft Dysfunction and Management in Liver Transplantation

Graft dysfunction of the liver allograft manifests across a spectrum in both timing posttransplantation and clinical presentation. This can range from mild transient abnormalities of liver tests to acute liver failure potentially leading to graft failure. The causes of graft dysfunction can be divided into those resulting in early and late graft dysfunction. Although nonspecific, liver biochemistry abnormalities are still the mainstay investigation used in monitoring for dysfunction. This article provides a summary of the main causes and management strategies for liver graft dysfunction in the early through late posttransplant stages.

Graft survival after liver transplantation: an approach to a new Spanish risk index

INTRODUCTION

several indicators are available to assess liver graft survival, including the American DRI and the European ET-DRI. However, there are significant differences between transplant programs of different countries, and the previously mentioned indicators might be not valid in our setting.

OBJECTIVES

the aim of the study was to describe a new national liver graft risk indicator based on the results obtained from the Registro Español de Trasplante Hepático (RETH) and to validate the DRI and ET-DRI indicators.

METHODS

the RETH includes a Cox analysis of factors associated with graft survival; the graft risk index (GRI) indicator was defined based on these results. The variables considered are dependent upon the donation conditions (age, cause of death, blood compatibility and cold ischemia time) and the transplant recipient (age, underlying disease, hepatitis C virus, transplant number, UNOS status and surgical technique). A logistic regression curve was obtained and graft survival curves were calculated by stratification. Precision was assessed using the ROC analysis.

RESULTS

a GRI of 1 represents a probability of graft loss of 23.25%; each point increase in the GRI score multiplies this probability by 1.33. The best discrimination of GRI was obtained by stratification. The DRI ROC area was 0.54 (95% CI, 0.50-0.59) and the ET-DRI ROC area was 0.56 (95% CI, 0.51-0.61), compared to 0.70 (95% CI, 0.65-0.73) (p < 0.0001) for the GRI.

CONCLUSIONS

both the DRI and ET-DRI do not seem to be useful in our setting. Hence a national indicator is more desirable. The GRI requires a national study in order to further streamline and assess this indicator.

Optimizing Livers for Transplantation Using Machine Perfusion versus Cold Storage in Large Animal Studies and Human Studies: A Systematic Review and Meta-Analysis

Background

Liver allograft preservation frequently involves static cold storage (CS) and machine perfusion (MP). With its increasing popularity, we investigated whether MP was superior to CS in terms of beneficial outcomes.

Methods

Human studies and large animal studies that optimized livers for transplantation using MP versus CS were assessed (PubMed/Medline/EMBASE). Meta-analyses were conducted for comparisons. Study quality was assessed according to the Newcastle-Ottawa quality assessment scale and SYRCLE's risk of bias tool.

Results

Nineteen studies were included. Among the large animal studies, lower levels of lactate dehydrogenase (SMD -3.16, 95% CI -5.14 to -1.18), alanine transferase (SMD -2.46, 95% CI -4.03 to -0.90), and hyaluronic acid (SMD -2.48, 95% CI -4.21 to -0.74) were observed in SNMP-preserved compared to CS-preserved livers. NMP-preserved livers showing lower level of hyaluronic acid (SMD -3.97, 95% CI -5.46 to -2.47) compared to CS-preserved livers. Biliary complications (RR 0.45, 95% CI 0.28 to 0.73) and early graft dysfunction (RR 0.56, 95% CI 0.34 to 0.92) also significantly reduced with HMP preservation in human studies. No evidence of publication bias was found.

Conclusions

MP preservation could improve short-term outcomes after transplantation compared to CS preservation. Additional randomized controlled trials (RCTs) are needed to develop clinical applications of MP preservation.

Molecular hydrogen protects against ischemia-reperfusion injury in a mouse fatty liver model via regulating HO-1 and Sirt1 expression

Fatty liver has lower tolerance against ischemia-reperfusion (I/R) injury in liver operations, including liver transplantation. Seeking to ameliorate liver injury following I/R in fatty liver, we examined the protective effect of hydrogen (H₂) saline on I/R liver injury in a methionine and choline-deficient plus high fat (MCDHF) diet-induced fatty liver mouse model. Saline containing 7 ppm H₂ was administrated during the process of I/R. Livers were obtained and analyzed. Primary hepatocytes and Kupffer cells (KCs) were obtained from fatty liver and subjected to hypoxia/reoxygenation. Apoptosis-related proteins and components of the signaling pathway were analyzed after treatment with hydrogen gas. The MCDHF I/R group showed higher levels of AST and ALT in serum, TUNEL-positive apoptotic cells, F4/80 immunopositive cells, mRNA levels of inflammatory cytokines, constituents of the signaling pathway, pro-apoptotic molecules in liver, and KCs and/or primary hepatocytes, compared to the control group. In contrast, H₂ treatment significantly suppressed the signs of I/R injury in fatty liver. Moreover, the expression of Bcl-2, HO-1, and Sirt1 in liver, KCs, and hepatocytes by hydrogen gas were increased, whereas caspase activation, Bax, and acetylation of p53 were suppressed by hydrogen gas. These results demonstrated that H₂ treatment ameliorated I/R liver injury in a fatty liver model by reducing hepatocyte apoptosis, inhibiting macrophage activation and inflammatory cytokines, and inducing HO-1 and Sirt1 expression. Taken togather, treatment with H₂ saline may have a protective effect and safe therapeutic activity during I/R events, such as in liver transplantation with fatty liver.

Assessment of liver ischemia reperfusion injury in mice using hepatic T2 mapping: Comparison with histopathology

BACKGROUND

Liver ischemia reperfusion injury (IRI) occurs during liver surgery or transplantation resulting in an inflammatory response, tissue damage, and functional impairment of the organ.

PURPOSE

To assess the feasibility of T₂ mapping for noninvasive quantification of liver edema after partial liver IRI in mice.

STUDY TYPE

Prospective, experimental study.

ANIMAL MODEL

Partial liver IRI was induced in C57BL/6-mice by transient clamping of the left lateral and median liver lobes for 35 (n = 8), 45 (n = 6), 60 (n = 17), or 90 minutes (n = 5). For comparison, healthy C57BL/6-mice were examined as controls (n = 9).

FIELD STRENGTH/SEQUENCE

Functional liver MRI was performed on a 7T scanner using a respiratory-triggered multiecho spin-echo sequence.

ASSESSMENT

Healthy control mice and mice with partial liver IRI on day 1 after surgery, and additionally on day 7 in a subgroup with 60 minutes IRI (n = 8) were examined. Maps of T₂ relaxation time of liver tissue were used to assess distribution, severity of tissue edema (mean T₂ time), and the percentage of edematous liver tissue.

STATISTICAL TEST

One-way analysis of variance (ANOVA) with Tukey's honest significant difference (HSD), paired t-tests, Pearson's test for correlation of MRI parameters with levels of liver enzymes, and histopathology, receiver operating characteristic (ROC) analysis.

RESULTS

Significant tissue edema induced by liver IRI as compared to the control group was detected by increased mean T₂ times in groups with 60 minutes (P < 0.001) and 90 minutes IRI (P < 0.001). The percentage of edematous liver tissue significantly increased with longer ischemia times (controls 3.4 ± 0.4%, 35 minutes 5.3 ± 0.6%, 45 minutes 23.3 ± 7.6%, 60 minutes 39.7 ± 3.6%, 90 minutes 51.3 ± 4.5%). Mean T₂ times and the percentage of edematous liver tissue significantly correlated with elevation of liver enzymes (P < 0.001), histological evidence of liver injury (r = 0.80 and r = 0.82, P < 0.001), and neutrophil infiltration (r = 0.70 and r = 0.74, P < 0.001). In the subgroup with follow-up, the severity (P < 0.01) and extent of liver edema decreased significantly over time (P < 0.01).

DATA CONCLUSION

T₂ mapping allows quantification and follow-up of liver injury in mice.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;48:1586-1594.

Nonalcoholic fatty liver disease and liver transplantation - Where do we stand?

Nonalcoholic fatty liver disease/nonalcoholic steatohepatitis (NAFLD/NASH) is a challenging and multisystem disease that has a high socioeconomic impact. NAFLD/NASH is a main cause of macrovesicular steatosis and has multiple impacts on liver transplantation (LT), on patients on the waiting list for transplant, on post-transplant setting as well as on organ donors. Current data indicate new trends in the area of chronic liver disease. Due to the increased incidence of metabolic syndrome (MetS) and its components, NASH cirrhosis and hepatocellular carcinoma caused by NASH will soon become a major indication for LT. Furthermore, due to an increasing incidence of MetS and, consequently, NAFLD, there will be more steatotic donor livers and less high quality organs available for LT, in addition to a lack of available liver allografts. Patients who have NASH and are candidates for LT have multiple comorbidities and are unique LT candidates. Finally, we discuss long-term grafts and patient survival after LT, the recurrence of NASH and NASH appearing de novo after transplantation. In addition, we suggest topics and areas that require more research for improving the health care of this increasing patient population.

Grade of donor liver microvesicular steatosis does not affect the postoperative outcome after liver transplantation

BACKGROUND

The potential effect of graft steatosis on the postoperative liver function is discussed controversially. The present study aimed to evaluate the effect of the donor liver microvesicular steatosis on the postoperative outcome after liver transplantation.

METHODS

Ninety-four patients undergoing liver transplantation at the University Hospital Aachen were included in this study. The patient cohort was divided into three groups according to the grade of microvesicular steatosis (MiS): MiS <30% (n=27), MiS 30%-60% (n=41) and MiS >60% (n=26). The outcomes after liver transplantation were evaluated, including the 30-day and 1-year patient and graft survival rates and the incidences of early allograft dysfunction (EAD) and primary nonfunction (PNF).

RESULTS

The incidences of EAD and PNF did not differ significantly between the groups. We observed 5 cases of PNF, one occurred in the MiS <30% group and 4 in the MiS 30%-60% group. The 30-day and 1-year graft survivals did not differ significantly between groups. The 30-day patient survival rates were 100% in all groups. The 1-year patient survival rates were 94.4% in the MiS <30% group, 87.9% in the MiS 30%-60% group and 90.9% in the MiS >60% group.

CONCLUSION

Microvesicular steatosis of donor livers has no negative effect on the postoperative outcome after liver transplantation.