Expanding Postmortem Donor Pool Using Steatotic Liver Grafts: A New Look

Potential of Raman-Reflectance Combination in Quantifying Liver Steatosis and Fat Droplet Size: Evidence From Monte Carlo Simulations and Phantom Studies

This study explores a combined strategy of Raman and reflectance spectroscopy for quantifying liver fat content and fat droplet size, crucial in assessing donor livers. By using Monte Carlo simulations and experimental setups with oil-in-water phantoms, our findings indicate that Raman scattering can solely differentiate between varying fat contents. At the same time, reflectance intensity is influenced by both fat content and oil droplet size, with a more pronounced sensitivity to fat droplet size. This study demonstrates the efficacy of combined Raman and reflectance spectroscopy in assessing liver steatosis and fat droplet size, potentially aiding in assessing donor livers for transplantation.

Enhanced Artificial Intelligence Methods for Liver Steatosis Assessment Using Machine Learning and Color Image Processing: Liver Color Project

BACKGROUND

The use of livers with significant steatosis is associated with worse transplantation outcomes. Brain death donor liver acceptance is mostly based on subjective surgeon assessment of liver appearance, since steatotic livers acquire a yellowish tone. The aim of this study was to develop a rapid, robust, accurate, and cost-effective method to assess liver steatosis.

METHODS

From June 1, 2018, to November 30, 2023, photographs and tru-cut needle biopsies were taken from adult brain death donor livers at a single university hospital for the study. All the liver photographs were taken by smartphones then color calibrated, segmented, and divided into patches. Color and texture features were then extracted and used as input, and the machine learning method was applied. This is a collaborative project between Vall d'Hebron University Hospital and Barcelona MedTech, Pompeu Fabra University, and is referred to as LiverColor.

RESULTS

A total of 192 livers (362 photographs and 7240 patches) were included. When setting a macrosteatosis threshold of 30%, the best results were obtained using the random forest classifier, achieving an AUROC = 0.74, with 85% accuracy.

CONCLUSION

Machine learning coupled with liver texture and color analysis of photographs taken with smartphones provides excellent accuracy for determining liver steatosis.

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.

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

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

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

BACKGROUND

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

METHODS

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

RESULT

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

CONCLUSIONS

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

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

Aim

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

Methods

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

Results

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

Conclusion

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

Impact of Donor Liver Macrovesicular Steatosis on Deceased Donor Yield and Posttransplant Outcome

BACKGROUND

The Scientific Registry of Transplant Recipients (SRTR) had not traditionally considered biopsy results in risk-adjustment models, yet biopsy results may influence outcomes and thus decisions regarding organ acceptance.

METHODS

Using SRTR data, which includes data on all donors, waitlisted candidates, and transplant recipients in the United States, we assessed (1) the impact of macrovesicular steatosis on deceased donor yield (defined as number of livers transplanted per donor) and 1-y posttransplant graft failure and (2) the effect of incorporating this variable into existing SRTR risk-adjustment models.

RESULTS

There were 21 559 donors with any recovered organ and 17 801 liver transplant recipients included for analysis. Increasing levels of macrovesicular steatosis on donor liver biopsy predicted lower organ yield: ≥31% macrovesicular steatosis on liver biopsy was associated with 87% to 95% lower odds of utilization, with 55% of these livers being discarded. The hazard ratio for graft failure with these livers was 1.53, compared with those with no pretransplant liver biopsy and 0% to 10% steatosis. There was minimal change on organ procurement organization-specific deceased donor yield or program-specific posttransplant outcome assessments when macrovesicular steatosis was added to the risk-adjustment models.

CONCLUSIONS

Donor livers with macrovesicular steatosis are disproportionately not transplanted relative to their risk for graft failure. To avoid undue risk aversion, SRTR now accounts for macrovesicular steatosis in the SRTR risk-adjustment models to help facilitate use of these higher-risk organs. Increased recognition of this variable may also encourage further efforts to standardize the reporting of liver biopsy results.

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

Supplemental Digital Content is available in the text.

Background.

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

Methods.

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

Results.

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

Conclusions.

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Noninvasive Estimation of Hepatic Steatosis by Controlled Attenuation Parameter in Living Donor Liver Transplant

OBJECTIVES

Estimation of liver fat among living donor candidates is necessary before living donor liver transplant. This study aimed to investigate the usefulness of the controlled attenuation parameter compared with liver biopsy for pretransplant estimation of hepatic steatosis in living liver donors.

MATERIALS AND METHODS

In this retrospective study, we included all individuals who underwent transient elastography with controlled attenuation parameter and ultrasonography-guided liver biopsy as a part of donor evaluations before living donor liver transplant. Clinical and laboratory data of living donor candidates were reviewed and collected.

RESULTS

Of 49 donor candidates included in this study, 21 (42.9%) had different degrees of hepatic macrosteatosis. Of the 21 donor candidates who had hepatic steatosis in liver biopsy, 13 individuals were diagnosed to have steatosis in transient elastography. Of the 28 donor candidates without hepatic steatosis in liver biopsy, 26 individuals showed no steatosis in transient elastography (odds ratio: 21.12; 95% CI, 3.91- 114.08; P < .001). Controlled attenuation parameter was useful in discriminating presence (P = .001) and grade of hepatic steatosis (P = .009) compared with liver biopsy with good sensitivity and specificity.

CONCLUSIONS

The controlled attenuation parameter is a noninvasive method for detection of hepatic steatosis in living donor candidates and can be used as an adjunct to liver biopsy for screening of living donor candidates before liver transplant.

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.

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.

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.

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

Background

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

Methods

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

Results

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

Conclusions

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

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

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

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

Background and Aims

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

Methods

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

Results

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

Conclusions

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

Donor Small-Droplet Macrovesicular Steatosis Affects Liver Transplant Outcome in HCV-Negative Recipients

BACKGROUND

No data are available on liver transplantation (LT) outcome and donor liver steatosis, classified as large droplet macrovesicular (Ld-MaS), small-droplet macrovesicular (Sd-MaS), and true microvesicular (MiS), taking into account the recipient Hepatitis C virus (HCV) status.

AIM

We investigate the impact of allograft steatosis reclassified according to the Brunt classification on early graft function and survival after LT.

METHODS

We retrospectively reviewed 204 consecutive preischemia biopsies of grafts transplanted in our center during the period 2001-2011 according to recipient HCV status.

RESULTS

The median follow-up after LT was 7.5 years (range: 0.0-16.7). In negative recipients (n=122), graft loss was independently associated with graft Sd-MaS, in multivariable Cox regression models comprehending only pre-/intraoperative variables (HR=1.03, 95%CI=1.01-1.05; P=0.003) and when including indexes of early postoperative graft function (HR=1.04, 95%CI=1.02-1.06; P=0.001). Graft Sd-MaS>15% showed a risk for graft loss > 2.5-folds in both the models. Graft Sd-MaS>15% was associated with reduced graft ATP content and, only in HCV- recipients, with higher early post-LT serum AST peaks.

CONCLUSIONS

In HCV-negative recipients, allografts with >15% Sd-MaS have significantly reduced graft survival and show low ATP and higher AST peaks in the immediate posttransplant period. Donors with >15% Sd-MaS have significantly higher BMI, longer ICU stays, and lower PaO2.

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.

The "Skinny" on Assessment and Utilization of Steatotic Liver Grafts: A Systematic Review

The frequency at which steatotic deceased donor liver grafts are encountered will likely continue to increase. Utilization of liver grafts with moderate-to-severe steatosis for liver transplantation (LT) has been previously shown to be associated with increased rates of primary nonfunction and decreased recipient survival. In order to better inform clinical decision making and guide future research, critical evaluation of the literature on donor liver steatosis and posttransplantation outcome is needed. This literature review aims to provide the "skinny" on using deceased donor steatotic livers for LT.

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.

Impact of Graft Steatosis on Postoperative Complications after Liver Transplantation

Background  Steatotic grafts are more susceptible to ischemia-reperfusion injury than are normal grafts. Therefore, using steatotic grafts for liver transplantation (LT) is associated with high primary dysfunction and decreased survival rates. The aim of this study is to evaluate the impact of graft steatosis on post LT outcomes. Methods  A retrospective cohort analysis of 271 LT recipients from 2005 to 2016 was performed and patients were classified based on two types of steatosis, macrosteatosis (MaS), and microsteatosis (MiS). Each category was subdivided into three groups according to the degree of steatosis: no (< 5%), mild (≥5 to < 30%), and moderate (≥30 to ≤60%). The primary hospital stays and 6-month postoperative complications were analyzed by the Clavien-Dindo classification system. Additionally, patient and graft survivals were studied. Results  Significant differences were observed in grade III MaS ( p -value = 0.019) and grade V MiS ( p -value = 0.020). A high trend of early graft dysfunction was found in the moderate MaS and MiS groups; however, they were not statistically significant ( p -value = 0.199 and 0.282, respectively). Interestingly, the acute cellular rejection (ACR) rate was found to be inversely proportional to the degree of steatosis in both categories but it did not reach a significant level ( p -value = 0.161 and 0.111, respectively). Conclusion  Excellent post LT long-term outcomes using grafts with mild and moderate steatosis were determined. Further studies are needed to evaluate the newly proposed relationship between ACR and steatosis.

Short-term and long-term outcomes of liver transplantation using moderately and severely steatotic donor livers: A systematic review

BACKGROUND

The aim of this study was to perform a systemic review of the studies addressing the use of moderately and severely steatotic donor livers for liver transplantation.

METHODS

We searched the following electronic databases from January 1, 1989, to August 1, 2017: PubMed, EMBASE, Science Citation Index Expanded, and the Cochrane Library. In addition, reference lists were scanned to identify any additional reports. The quality of published papers was assessed. The main outcomes of the use of moderately and severely steatotic donor livers for liver transplantation, including primary nonfunction, short-term mortality, and long-term mortality, were extracted for pooled analysis.

RESULTS

Literature searches identified 16 studies that met the inclusion criteria. There were no randomized controlled studies, and all of the studies were retrospective or prospective case series. From a total of 3226 subjects (532 moderately and severely steatotic donor livers and 2694 controls), we found a significant increase in primary nonfunction [odds ratio (OR): 2.47, 95% confidence interval (95% CI): 1.44-4.27], and a trend of increase in 1-month patient mortality (OR: 1.90, 95% CI: 0.98-3.71) with the use of moderately and severely steatotic donor livers, whereas the 1-year mortality was relatively less influenced.

CONCLUSION

The use of moderately and severely steatotic livers is associated with unfavorable short-term outcomes, but long-term outcomes are relatively less influenced.

The impact of diet-induced hepatic steatosis in a murine model of hepatic ischemia/reperfusion injury

The prevalence of obesity-associated nonalcoholic fatty liver disease has significantly increased over the past decade, and end-stage liver disease secondary to nonalcoholic steatohepatitis has become 1 of the most common indications for liver transplantation. This both increases the demand for organs and decreases the availability of donor livers deemed suitable for transplantation. Although in the past many steatotic livers were discarded due to concerns over enhanced susceptibility to ischemia/reperfusion injury (IRI) and organ failure, the discrepancy between supply and demand has resulted in increasing use of expanded criteria donor organs including steatotic livers. However, it remains controversial whether steatotic livers can be safely used for transplantation and how best to improve the performance of steatotic grafts. We aimed to evaluate the impact of diet-induced hepatic steatosis in a murine model of IRI. Using a diet of high trans-fat, fructose, and cholesterol (HTF-C) and a diet high in saturated fats, sucrose, and cholesterol (Western diet), we were able to establish models of mixed macrovesicular and microvesicular steatosis (HTF-C) and microvesicular steatosis (Western). We found that the presence of hepatic steatosis, whether it is predominantly macrovesicular or microvesicular, significantly worsens IRI as measured by plasma alanine aminotransferase levels and inflammatory cytokine concentration, and histological evaluation for necrosis. Additionally, we report on a novel finding in which hepatic IRI in the setting of steatosis results in the induction of the necroptosis factors, receptor interacting protein kinase (RIPK) 3, RIPK1, and mixed-lineage kinase domain-like. These data lay the groundwork for additional experimentation to test potential therapeutic approaches to limit IRI in steatotic livers by using a genetically tractable system. Liver Transplantation 24 908-921 2018 AASLD.

Diaphragm Muscle Surface Electromyography in Patients Submitted to Liver Transplant and Eligible for Extubation

INTRODUCTION

Liver disease induces many organic and metabolic changes, leading to malnutrition and weight and muscular function loss. Surface electromyography is an easily applicable, noninvasive study, through which the magnitudes of the peaks on the charts depict voluntary muscle activity.

AIM

To evaluate the diaphragmatic surface electromyography of postoperative liver transplantation subjects.

METHODS

Subjects were patients who underwent liver transplantation and extubation in the Clinical Hospital of State University of Campinas. Electromyography data were collected with support pressure of ≤10 cm H₂O, Glasgow Coma Scale = 11, and minimum dosages of vasoactive drugs, and data were collected again 30 minutes after extubation. Signal collection was performed with sEMG System Brazil SAS1000V3 electromyograph and electrode stickers. Statistical analysis was performed using R software.

RESULTS

The average time of surgery was 345.36 ± 125.62 minutes. Time from spontaneous mode until extubation was 417.14 ± 362.97 minutes. The RMS (root mean square) values of the right and left domes in spontaneous mode with minimal ventilation parameters were 26.68 ± 10.92 and 26.55 ± 10.53, respectively, and the RMS values after extubation were 31.93 ± 18.69 to 34.62 ± 13.55, for right and left domes. The last calculated pretransplant Model for End-stage Liver Disease score averaged 19.64 ± 8.41.

CONCLUSION

There were significant differences between the RMS of the diaphragm domes under mechanical ventilation and after extubation, showing lower effectiveness of the diaphragm muscle against resistance, without the aid of positive pressure and the existing overload of the left dome.

Extended-criteria donors in liver transplantation Part II: reviewing the impact of extended-criteria donors on the complications and outcomes of liver transplantation

Extended-criteria donors (ECDs) have an impact on early allograft dysfunction (EAD), biliary complications, relapse of hepatitis C virus (HCV), and survivals. Early allograft dysfunction was frequently seen in grafts with moderate and severe steatosis. Donors after cardiac death (DCD) have been associated with higher rates of graft failure and biliary complications compared to donors after brain death. Extended warm ischemia, reperfusion injury and endothelial activation trigger a cascade, leading to microvascular thrombosis, resulting in biliary necrosis, cholangitis, and graft failure. The risk of HCV recurrence increased by donor age, and associated with using moderately and severely steatotic grafts. With the administration of protease inhibitors sustained virological response was achieved in majority of the patients. Donor risk index and EC donor scores (DS) are reported to be useful, to assess the outcome. The 1-year survival rates were 87% and 40% respectively, for donors with a DS of 0 and 3. Graft survival was excellent up to a DS of 2, however a DS >2 should be avoided in higher-risk recipients. The 1, 3 and 5-year survival of DCD recipients was comparable to optimal donors. However ECDs had minor survival means of 85%, 78.6%, and 72.3%. The graft survival of split liver transplantation (SLT) was comparable to that of whole liver orthotopic liver transplantation. SLT was not regarded as an ECD factor in the MELD era any more. Full-right-full-left split liver transplantation has a significant advantage to extend the high quality donor pool. Hypothermic oxygenated machine perfusion can be applied clinically in DCD liver grafts. Feasibility and safety were confirmed. Reperfusion injury was also rare in machine perfused DCD livers.

Donor Hepatic Steatosis Induce Exacerbated Ischemia-Reperfusion Injury Through Activation of Innate Immune Response Molecular Pathways

BACKGROUND

Severe liver steatosis is a known risk factor for increased ischemia-reperfusion injury (IRI) and poor outcomes after liver transplantation (LT). This study aimed to identify steatosis-related molecular mechanisms associated with IRI exacerbation after LT.

METHODS

Paired graft biopsies (n = 60) were collected before implantation (L1) and 90 minutes after reperfusion (L2). The LT recipients (n = 30) were classified by graft macrosteatosis: without steatosis (WS) of 5% or less (n = 13) and with steatosis (S) of 25% or greater (n = 17). Plasma samples were collected at L1, L2, and 1 day after LT (postoperative [POD]1) for cytokines evaluation. Tissue RNA was isolated for gene expression microarrays. Probeset summaries were obtained using robust multiarray average algorithm. Pairwise comparisons were fit using 2-sample t test. P values 0.01 or less were significant (false discovery rate <5%). Molecular pathway analyses were conducted using Ingenuity Pathway Analysis tool.

RESULTS

Significantly differentially expressed genes were identified for WS and S grafts after reperfusion. Comprehensive comparison analysis of molecular profiles revealed significant association of S grafts molecular profile with innate immune response activation, macrophage production of nitric oxide and reactive oxygen species, IL-6, IL-8, IL-10 signaling activation, recruitment of granulocytes, and accumulation of myeloid cells. Postreperfusion histological patterns of S grafts revealed neutrophilic infiltration surrounding fat accumulation. Circulating proinflammatory cytokines after reperfusion and 24 hours after LT concurred with intragraft-deregulated molecular pathways. All tested cytokines were significantly increased in plasma of S grafts recipients after reperfusion when compared with WS group at same time.

CONCLUSIONS

Increases of graft steatosis exacerbate IRI by exacerbation of innate immune response after LT. Preemptive strategies should consider it for safety usage of steatotic livers.

Excellent outcomes of liver transplantation using severely steatotic grafts from brain-dead donors

Liver grafts with macrovesicular steatosis of > 60% are considered unsuitable for deceased donor liver transplantation (DDLT) because of the unacceptably high risk of primary nonfunction (PNF) and graft loss. This study reports our experience in using such grafts from brain-dead donors. Prospectively collected data of DDLT recipient outcomes from 1991 to 2013 were retrospectively analyzed. Macrovesicular steatosis > 60% at postperfusion graft biopsy was defined as severe steatosis. In total, 373 patients underwent DDLT. Nineteen patients received severely steatotic grafts (ie, macrovesicular steatosis > 60%), and 354 patients had grafts with ≤ 60% steatosis (control group). Baseline demographics were comparable except that recipient age was older in the severe steatosis group (51 versus 55 years; P = 0.03). Median Model for End-Stage Liver Disease (MELD) score was 20 in the severe steatosis group and 22 in the control group. Cold ischemia time (CIT) was 384 minutes in the severe steatosis group and 397.5 minutes in the control group (P = 0.66). The 2 groups were similar in duration of stay in the hospital and in the intensive care unit. Risk of early allograft dysfunction (0/19 [0%] versus 1/354 [0.3%]; P>0.99) and 30-day mortality (0/19 [0%] versus 11/354 [3.1%]; P = 0.93) were also similar between groups. No patient developed PNF. The 1-year and 3-year overall survival rates in the severe steatosis group were both 94.7%. The corresponding rates in the control group were 91.8% and 85.8% (P = 0.55). The use of severely steatotic liver grafts from low-risk donors was safe, and excellent outcomes were achieved; however, these grafts should be used with caution, especially in patients with high MELD score. Keeping a short CIT was crucial for the successful use of such grafts in liver transplantation.

Donor Hepatic Steatosis and Outcome After Liver Transplantation: a Systematic Review

BACKGROUND

There is increasing need to expand availability of donor liver grafts, including steatotic livers. Steatotic liver is associated with poor outcome post-transplantation but with conflicting results in the literature. The aim of this systematic review was to evaluate the impact of steatotic livers on liver transplantation outcomes.

METHODS

An electronic search of OVID Medline and Embase databases was performed to identify clinical studies that reported outcomes of steatotic livers in liver transplantation. Data were extracted, and basic descriptive statistics were used to summarise data pooled from individual clinical studies.

RESULTS

Ninety-two articles were identified, of which 34 met the inclusion criteria, and stratified analysis were performed. There was a lack of standardised definition of primary non-function or impaired primary function amongst the studies and description of type of steatosis. Severely (>60%) steatotic grafts are associated with increased risk of poor graft function, whilst moderate-severe (>30%) steatotic grafts are associated with decreased graft survival.

CONCLUSIONS

Available evidence showed increased risk of poor graft outcome in moderate-severe steatotic livers. A large prospective multi-centred trial will be required to identify the true risks of steatotic livers. Consistent definition of primary non-function/impaired primary function and description of type of steatosis is also required.

Similar outcome after transplantation of moderate macrovesicular steatotic and nonsteatotic livers when the cold ischemia time is kept very short

BACKGROUND

Livers with moderate (30-60%) macrovesicular steatosis have been associated with poor outcome after transplantation. Aim of this study was to examine the outcome after transplantation of livers with moderate macrovesicular steatosis when the cold ischemia time (CIT) is kept very short.

METHODS

Postoperative outcome of 19 recipients of a moderate steatotic liver were compared with a matched control group of 95 recipients of a nonsteatotic liver graft (1:5 ratio). We studied graft/patient survival rates, incidences of primary nonfunction, postoperative complications (classified according to the Clavien-Dindo classification), first-week postoperative hepatic injury serum markers (AST/ALT), and liver function tests (PT time/bilirubin/lactate). In addition, we studied reversal of graft steatosis in follow-up biopsies.

RESULTS

Median CIT in livers with moderate steatosis and in controls was below 8 h in both groups. Although short- and long-term patient/graft survival rates and results of liver function tests were similar, serum markers of hepatic injury and postoperative complications (especially grade IVa) were significantly higher in recipients of a moderate steatotic liver. Reversal of steatosis was seen in 9 of the 11 (82%) recipients with follow-up liver biopsies.

CONCLUSION

Despite the association with severe postoperative complications, moderate macrovesicular steatotic livers can be used successfully for transplantation if the CIT is kept very short.

Comparison of the tolerance of hepatic ischemia/reperfusion injury in living donors: macrosteatosis versus microsteatosis

A safe use of intermittent hepatic inflow occlusion (IHIO) has been reported for living donor hepatectomy. However, it remains unclear whether the maneuver is safe in steatotic donors. In addition, the respective importance of macrosteatosis (MaS) and microsteatosis (MiS) is an important issue. Thus, we compared MiS and MaS with respect to the tolerance of hepatic ischemia/reperfusion (IR) injury induced by IHIO. One hundred forty-four donors who underwent a right hepatectomy were grouped according to the presence of MaS and MiS: a non-MaS group (n = 68) versus an MaS group (n = 76) and a non-MiS group (n = 51) versus an MiS group (n = 93). The coefficients of the regression lines between the cumulative IHIO time and the peak postoperative transaminase concentrations were used as surrogate parameters indicating the tolerance of hepatic IR injury. The coefficients were significantly greater for the MaS group versus the non-MaS group (4.12 ± 0.59 versus 2.22 ± 0.46 for alanine aminotransferase, P = 0.01). Conversely, the MiS and non-MiS groups were comparable. A subgroup analysis of donors who underwent IHIO for >30 minutes showed that MaS significantly increased the transaminase concentrations, whereas MiS had no impact. Also, IHIO for >30 minutes significantly increased the biliary complication rate for MaS donors (12.1% for ≤ 30 minutes versus 32.6% for >30 minutes, P = 0.04), whereas MiS donors were not affected. In conclusion, the tolerance of hepatic IR injury might differ between MaS livers and MiS livers. It would be rational to assign more clinical importance to MaS versus MiS. We further recommend limiting the cumulative IHIO time to 30 minutes or less for MaS donors undergoing right hepatectomy.

Improved access to histopathology using a digital system could increase the organ donor pool and improve allocation

Improvements in digital slide scanners have reached a stage that digital whole slide images (WSIs) can be used for diagnostic purposes. A digital system for histopathology, analogous to the systems used in radiology, would allow the establishment of networks of subspecialist histopathologists to provide a regional, national or even international rota to support out of hours histopathology for emergency frozen sections, urgent paraffin sections and to generally improve efficiencies with the provision of histopathology services. Such a system would promote appropriate organ utilization by allowing rapid characterization of unexpected lesions in the donor to determine whether donation should occur and further characterization of the organ, such as the degree of fibrosis in the kidney or steatosis in the liver, to determine whether the organ should be used. If introduced across Europe, this would promote safe and effective exchange of organs and support a cost efficient use of pathologist expertise. This review article outlines current issues with the provision of an urgent out of hours histopathology service and focuses on how such a service has the potential to increase organ donors, improve allocation, sharing and the use of available donor organs.

Effect of pure microsteatosis on transplant outcomes after living donor liver transplantation: a matched case-control study

Liver steatosis mostly exists in a mixed form of macrosteatosis (MaS) and microsteatosis (MiS). This coexistence is responsible for previous conflicting results regarding the importance of MiS in liver transplantation. We aimed to evaluate the independent effect of MiS on posttransplant outcomes with the exclusion of the confounding effect of MaS. Seventy-one living donors who had pure MiS (defined as an MiS degree > 5% without MaS) were matched 1:1 with control donors, and 66 recipients who received pure MiS grafts were matched 1:1 with control recipients on the basis of propensity scores. Matched variables included the donor age, remnant liver volume, cold ischemia time, graft-to-recipient weight ratio and Model for End-Stage Liver Disease score. The degree of pure MiS ranged from 5% to 50%. Donors in the control and pure MiS groups were comparable with respect to peak postoperative transaminase concentrations [alanine aminotransferase (ALT): 194 versus 176 IU/L, P = 0.61] and postoperative complications. Recipients in the control and pure MiS groups were comparable with respect to recipient (P = 0.15) and graft survival rates (P = 0.56) as well as peak postoperative transaminase concentrations (ALT: 266 versus 281 IU/L, P = 0.88), and graft regeneration rates at 2 weeks (61% versus 59%, P = 0.73). The 2 groups were also comparable with respect to major complications, primary graft dysfunction/nonfunction, intensive care unit/hospital stays, and metabolic diseases. In conclusion, MiS alone does not seem to impair the posttransplant outcomes of living donors and their recipients. The interaction between MiS and MaS, and the effect of a greater degree of MiS are the next important topics to be further evaluated in the mixed steatosis population.

Safe use of highly steatotic livers by utilizing a donor/recipient clinical algorithm

The aim of this study was to assess the long-term safety and clinical outcomes associated with the utilization of highly steatotic donor livers utilizing a specific donor/recipient matching algorithm. This was a prospective, observational, single-center, 10-yr follow-up study. Highly steatotic livers were utilized according to a donor/recipient algorithm that guided the surgeon to use highly steatotic donor organs judiciously in low-risk recipients. This study initially compared fat assessment based on frozen-section Ehrlich's hematoxylin and eosin (H&E) to reperfusion biopsy fat assessment and demonstrated that H&E is an insensitive analysis to determine degree of steatosis. Patients were divided into three groups based on donor steatosis (group 1: <30% steatosis, group 2: 30-60% steatosis, group 3: >60% steatosis), and clinical outcomes were assessed. One hundred and sixteen patients were included in the analysis. Patients that received severely steatotic livers (>60% fat) showed increased reperfusion liver injury and delayed return of liver function in the early postoperative period, demonstrated by biochemical markers. However, there were no differences in primary non-function, postoperative complications, length of stay, and patient and graft survival. Using rigorous donor/recipient matching through a detailed algorithm, these data demonstrate that normal liver allograft outcomes are not superior to those in highly steatotic grafts.

Prediction models of donor arrest and graft utilization in liver transplantation from maastricht-3 donors after circulatory death

Shortage of organs for transplantation has led to the renewed interest in donation after circulatory-determination of death (DCDD). We conducted a retrospective analysis (2001-2009) and a subsequent prospective validation (2010) of liver Maastricht-Category-3-DCDD and donation-after-brain-death (DBD) offers to our program. Accepted and declined offers were compared. Accepted DCDD offers were divided into donors who went on to cardiac arrest and those who did not. Donors who arrested were divided into those producing grafts that were transplanted or remained unused. Descriptive comparisons and regression analyses were performed to assess predictor models of donor cardiac arrest and graft utilization. Variables from the multivariate analysis were prospectively validated. Of 1579 DCDD offers, 621 were accepted, and of these, 400 experienced cardiac arrest after withdrawal of support. Of these, 173 livers were transplanted. In the DCDD group, donor age < 40 years, use of inotropes and absence of gag/cough reflexes were predictors of cardiac arrest. Donor age >50 years, BMI >30, warm ischemia time >25 minutes, ITU stay >7 days and ALT ≥ 4× normal rates were risk factors for not using the graft. These variables had excellent sensitivity and specificity for the prediction of cardiac arrest (AUROC = 0.835) and graft use (AUROC = 0.748) in the 2010 prospective validation. These models can feasibly predict cardiac arrest in potential DCDDs and graft usability, helping to avoid unnecessary recoveries and healthcare expenditure.

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

BACKGROUND AND AIM

Donor liver steatosis can impact on liver allograft outcomes. The aim of the present study was to comprehensively report on the impact of type and grade of donor steatosis, as well as donor and recipient factors, including the reported Donor Risk Index (DRI), on liver allograft outcomes.

METHODS

A review of unit data for all adult liver transplant procedures from 2001 to 2007, as well as donor offers. Donor liver biopsies were regraded for steatosis by an experienced histopathologist.

RESULTS

Steatosis was detected in 184/255 (72%) of biopsies, of which 114 (62%) had microvesicular steatosis (MiS; 68 mild, 22 moderate, 24 severe) and 70 (38%) macrovesicular steatosis (MaS; 59 mild, 7 moderate, 4 severe). The majority (66/70, 94%) of biopsies with MaS also contained MiS. Allograft steatosis was associated with increasing donor body mass index (P = 0.000), plus donor male sex (P < 0.05). Primary non function (P = 0.002), early renal failure (P = 0.040), and requirement for retransplantation (P = 0.012) were associated only with severe MaS. Early biliary complications were associated with moderate MaS (P = 0.039). Only severe MaS was significantly associated with inferior allograft survival at 3 months (relative risk = 12.09 [8.75-19.05], P = 0.000) and 1 year (P = 0.000).

CONCLUSIONS

MiS is a common finding and frequently coexists with MaS on liver allograft biopsy, while isolated MaS is uncommon. Only the presence of moderate to severe MaS is associated with inferior early allograft outcomes. The impact of severe MaS on allograft survival appears greater than other donor factors, including the calculated DRI.

PPARα is down-regulated following liver transplantation in mice

BACKGROUND & AIMS

Graft dysfunction is one of the major complications after liver transplantation, but its precise mechanism remains unclear. Since steatotic liver grafts are susceptible to post-transplant dysfunction, and peroxisome proliferator-activated receptor (PPAR) α plays an important role in the maintenance of hepatic lipid homeostasis, we examined the role of PPARα in liver transplantation.

METHODS

Livers were harvested from Sv/129 wild-type (Ppara(+/+)) mice and PPARα-null (Ppara(-/-)) mice and transplanted orthotopically into syngeneic Ppara(+/+) mice.

RESULTS

Hepatocellular damage was unexpectedly milder in transplanted Ppara(-/-) livers compared with Ppara(+/+) ones. This was likely due to decreased lipid peroxides in the Ppara(-/-) livers, as revealed by the lower levels of fatty acid oxidation (FAO) enzymes, which are major sources of reactive oxygen species. Hepatic PPARα and its target genes, such as FAO enzymes and pyruvate dehydrogenase kinase 4, were strongly down-regulated after transplantation, which was associated with increases in hepatic tumor necrosis factor-α expression and nuclear factor-κB activity. Inhibiting post-transplant PPARα down-regulation by clofibrate treatment markedly augmented oxidative stress and hepatocellular injury.

CONCLUSIONS

Down-regulation of PPARα seemed to be an adaptive response to metabolic alterations following liver transplantation. These results provide novel information to the understanding of the pathogenesis of early post-transplant events.

Impact of age on liver regeneration response to injury after partial hepatectomy in a rat model

BACKGROUND

Liver resection is a feasible treatment for multiple liver diseases. There is no evidence about the impact of age on liver regeneration.

OBJECTIVE

To assess the effect of age on liver regeneration in an experimental in vivo animal model of 70%-partial hepatectomy.

METHODS

Forty young (Y) and old (O) Wistar male rats (n = 80) were distributed into four groups [controls (C), sham operated (SO), hepatectomy 6 h (H6), and 48 h (H48)]. Different morphometric and biochemical factors, oxidative and nitrosative stress, lipid peroxidation, cytokines kinetics, and histopathologic tissular parameters were determined.

RESULTS

Early postoperative mortality was higher in aged rats (P = 0.049). Morphometric determinations, liver regeneration index, and total volume weight were favorable to young rats. Serum transaminase levels were higher in aged rats. Parameters of necrosis (measured by histopathologic injury [HI: 0-I-II-III]), regeneration (measured by bromodeoxyuridine-BrdU incorporation) and apoptosis (determined by the TDT-mediated dUTP nick end labeling-TUNEL) were well-synchronized in young rats. Parameters of oxidative stress such as reduced (GSH), oxidized (GSSG) glutathione and lipid peroxidation (measured by hepatic malondialdehyde -MDA-) were lower in young animals throughout the studied period. Nitrosative stress measured by nitric oxide (NO) end-products was higher in late stages in resected old rats. Pro-inflammatory cytokines (TNF- α) reached higher and earlier levels in aged rats while pro-regenerative cytokines (IL-6) were significantly higher in early stages for young rats and in late stages for aged rats. The levels of TGF-β were higher in young rats.

CONCLUSION

Liver regeneration is delayed and reduced in aged animals submitted to liver resection.

Utilization of elderly donors in living donor liver transplantation: when more is less?

An accepted definition of donor exclusion criteria has not been established for living donor liver transplantation (LDLT). The use of elderly donors to expand the living donor pool raises ethical concerns about donor safety. The aims of this study were (1) the comparison of the postoperative outcomes of living liver donors by age (≥ 50 versus < 50 years) and (2) the evaluation of the impact of the extent of right hepatectomy on donor outcomes. The study group included 150 donors who underwent donor right hepatectomy between October 2004 and April 2009. Extended criteria surgery (ECS) was defined as right hepatectomy with middle hepatic vein (MHV) harvesting or right hepatectomy resulting in an estimated remnant liver volume (RLV) less than 35%. The primary endpoints were donor outcomes in terms of donor complications graded according to the Clavien classification. Group 1 consisted of donors who were 50 years old or older (n = 28), and group 2 consisted of donors who were less than 50 years old (n = 122). At least 1 ECS criterion was present in 74% of donors: 57% had 1 criterion, and 17% had 2 criteria. None of the donors had grade 4 complications or died. The overall and major complication rates were similar in the 2 donor age groups [28.6% and 14.3% in group 1 and 32% and 8.2% in group 2 for the overall complication rates (P = 0.8) and the major complication rates (P = 0.2), respectively]. However, there was a significant correlation between the rate of major complications and the type of surgery in donors who were 50 years old or older. In LDLT, extending the limits of surgery comes at the price of more complications in elderly donors. Right hepatectomy with MHV harvesting and any procedure causing an RLV less than 35% should be avoided in living liver donors who are 50 years old or older.

Liver transplantation using fatty livers: always feasible?

Steatotic liver grafts represent the most common type of "extended criteria" organs that have been introduced during the last two decades due to the disparity between liver transplant candidates and the number available organs. A precise definition and reliable and reproducible method for steatosis quantification is currently lacking and the potential influence of the chemical composition of hepatic lipids has not been addressed. In our view, these shortcomings appear to contribute significantly to the inconsistent results of studies reporting on graft steatosis and the outcome of liver transplantation. In this review, various definitions, prevalence and methods of quantification of liver steatosis will be covered. Ischemia/reperfusion injury of the steatotic liver and its consequences on post-transplant outcome will be discussed. Selection criteria for organ allocation and a number of emerging protective strategies are suggested.

Critical care issues in patients after liver transplantation

The majority of patients who undergo liver transplantation (LT) spend some time in the intensive care unit during the postoperative period. For some, this is an expected part of the immediate posttransplant recovery period, whereas for others, the stay is more prolonged because of preexisting conditions, intraoperative events, or postoperative complications. In this review, 4 topics that are particularly relevant to the postoperative intensive care of LT recipients are discussed, with an emphasis on current knowledge specific to this patient group. Infectious complications are the most common causes of early posttransplant morbidity and mortality. The common patterns of infection seen in patients after LT and their management are discussed. Acute kidney injury and renal failure are common in post-LT patients. Kidney injury identification, etiologies, and risk factors and approaches to management are reviewed. The majority of patients will require weaning from mechanical ventilation in the immediate postoperative period; the approach to this is discussed along with the approach for those patients who require a prolonged period of mechanical ventilation. A poorly functioning graft requires prompt identification and appropriate management if the outcomes are to be optimized. The causes of poor graft function are systematically reviewed, and the management of these grafts is discussed.

High-grade microsteatosis and delay in hepatic function after orthotopic liver transplantation

Macrovesicular steatosis may be used to exclude potential donor livers from use in transplantation. Livers with more than 50% macrovesicular steatosis are believed to be at risk for delayed graft function and primary graft nonfunction. However, the significance of even extensive microsteatosis is uncertain. The hematoxylin and eosin-stained slides of postperfusion donor liver biopsies from 161 transplants were examined. The type of steatosis (macrovesicular, low-grade microvesicular, and high-grade microvesicular ) was determined, and the extent of each type was semiquantitated into 3 groups (none, ≤50%, and >50%). These were analyzed in conjunction with the donor and recipient age and the recipient's sex and MELD score against postoperative outcome parameters, including serial measures of serum lactate, days in the intensive care unit and overall in hospital, and death less than 3 months posttransplant. High-grade microsteatosis usually coexisted with macrosteatosis and infrequently with low-grade microsteatosis. There was no significant association between the extent of either macrosteatosis or low-grade microsteatosis (even when >50%) and any of the outcome parameters. In contrast, the presence of high-grade microsteatosis was significantly associated with delayed hepatic function, but not with the other outcome parameters. Donor age greater than 60 years was associated with late postoperative rise in serum lactate, and higher recipient MELD score was associated with extended stay in the intensive care unit and in the hospital. In this patient population, the association of steatosis with adverse outcomes was largely restricted to delay in postoperative hepatic function, and was due to the subgroup that displayed high-grade microsteatosis.