Effect of macrovescicular steatosis and other donor and recipient characteristics on the outcome of liver transplantation

Current Understanding of Marginal Grafts in Liver Transplantation

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

The role of adipose tissue and subsequent liver tissue hypoxia in obesity and early stage metabolic dysfunction associated steatotic liver disease

BACKGROUND

Obesity is linked to several health complication, including Metabolic Dysfunction Associated Steatotic Liver Disease (MASLD). Adipose tissue hypoxia has been suggested as an important player in the pathophysiological mechanism leading to chronic inflammation in obesity, and in the progression of MASLD. The study aims to investigate the effect of progressive obesity on adipose and liver tissue hypoxia.

METHODS

Male 8-week-old C57BL/6J mice were fed a high-fat high-fructose diet (HFHFD) or control diet (CD) for 4, 8, 12, 16 and 20 weeks. Serum ALT, AST and lipid levels were determined, and glucose and insulin tolerance testing was performed. Liver, gonadal and subcutaneous adipose tissue was assessed histologically. In vivo tissue pO2 measurements were performed in gonadal adipose tissue and liver under anesthesia. A PCR array for hypoxia responsive genes was performed in liver and adipose tissue. The main findings in the liver were validated in another diet-induced MASLD mice model, the choline-deficient L-amino acid defined high-fat diet (CDAHFD).

RESULTS

HFHFD feeding induced a progressive obesity, dyslipidaemia, insulin resistance and MASLD. In vivo pO2 was decreased in gonadal adipose tissue after 8 weeks of HFHFD compared to CD, and decreased further until 20 weeks. Liver pO2 was only significantly decreased after 16 and 20 weeks of HFHFD. Gene expression and histology confirmed the presence of hypoxia in liver and adipose tissue. Hypoxia could not be confirmed in mice fed a CDAHFD.

CONCLUSION

Diet-induced obesity in mice is associated with hypoxia in liver and adipose tissue. Adipose tissue hypoxia develops early in obesity, while liver hypoxia occurs later in the obesity development but still within the early stages of MASLD. Liver hypoxia could not be directly confirmed in a non-obese liver-only MASLD mice model, indicating that obesity-related processes such as adipose tissue hypoxia are important in the pathophysiology of obesity and MASLD.

de Moraes T, Fragoso GR. Prospective Study to Analyze the Concordance Between a Standardized Visual Method With Pathology to stratify Nonalcoholic Fatty Liver Disease in Cadaveric Liver Grafts Evaluated for Transplantation

Background

The main challenge of liver transplantation is the discrepancy in demand and availability. Marginal grafts or full organs from donors with expansion criteria have been considered to reduce the shortage and assist a greater number of patients. Nonalcoholic fatty liver disease (NAFLD) is one of the most important defining criteria for expanded criteria organs. The present study proposes that an organized visual analysis method could correctly identify and classify NAFLD and organ viability without the need for liver biopsy and its logistical concerns.

Methods

Pictures from the grafts were taken at a standardized method (same distance, light conditions, and register device) before and after the perfusion. The visual liver score (VLS) was applied by transplant surgeons; biopsies of the grafts were analyzed by a pathologist in a double-blind design. Score performance and interobserver agreement for NAFLD detection and grading, as graft viability evaluation, were calculated.

Results

Fifty-seven grafts were analyzed. At least 1 previous expansion criterion was presented by 59.64% of donors. The prevalence of NAFLD was 94.73%, with 31.57% borderline nonalcoholic steatohepatitis and 5.26% nonalcoholic steatohepatitis. Steatosis was identified with 48.68% (preperfusion) and 64.03% (postperfusion) accuracy. NAFLD stratification was performed with 49.53% (preperfusion) and 46.29% (postperfusion) accuracy. Viability related to NAFLD was identified with 51.96% (preperfusion) and 48.52% (postperfusion) accuracy. Interobserver agreement was moderate for total VLS and poor for individual components of VLS.

Conclusions

Although a standardized method was not reliable enough for visual evaluation of NALFD compared with pathology, efforts should be made to expand access to biopsy. Further studies are needed to understand whether the VLS needs to be adapted or even excluded in the liver transplant scenario, to assess the importance of ectoscopy related to posttransplant clinical outcomes, and to determine its role in graft selection.

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

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

A Novel Oxygen Carrier (M101) Attenuates Ischemia-Reperfusion Injuries during Static Cold Storage in Steatotic Livers

The combined impact of an increasing demand for liver transplantation and a growing incidence of nonalcoholic liver disease has provided the impetus for the development of innovative strategies to preserve steatotic livers. A natural oxygen carrier, HEMO2life^®, which contains M101 that is extracted from a marine invertebrate, has been used for static cold storage (SCS) and has shown superior results in organ preservation. A total of 36 livers were procured from obese Zucker rats and randomly divided into three groups, i.e., control, SCS-24H and SCS-24H + M101 (M101 at 1 g/L), mimicking the gold standard of organ preservation. Ex situ machine perfusion for 2 h was used to evaluate the quality of the livers. Perfusates were sampled for functional assessment, biochemical analysis and subsequent biopsies were performed for assessment of ischemia-reperfusion markers. Transaminases, GDH and lactate levels at the end of reperfusion were significantly lower in the group preserved with M101 (p < 0.05). Protection from reactive oxygen species (low MDA and higher production of NO2-NO3) and less inflammation (HMGB1) were also observed in this group (p < 0.05). Bcl-1 and caspase-3 were higher in the SCS-24H group (p < 0.05) and presented more histological damage than those preserved with HEMO2life^®. These data demonstrate, for the first time, that the addition of HEMO2life^® to the preservation solution significantly protects steatotic livers during SCS by decreasing reperfusion injury and improving graft function.

Magnetic resonance imaging-derived proton density fat fraction (MRI-PDFF) is a viable alternative to liver biopsy for steatosis quantification in living liver donor transplantation

This study aimed to investigate whether magnetic resonance imaging-derived proton density fat fraction (MRI-PDFF) can be a viable noninvasive alternative to liver biopsy for the quantification of living liver donor steatosis. Hepatic steatosis for 143 donors was graded by MRI-PDFF. Study endpoints included liver volume regeneration in donors, recipient outcomes including length of hospital stay, deaths, primary non-function (PNF), early allograft dysfunction (EAD), and small for size syndrome (SFSS). Correlation between MRI-PDFF determined donor steatosis and endpoints were analyzed. Donors had lower steatosis grade than non-donors. Donor remnant liver regenerated to an average of 82% of pre-donation volume by 101 ± 24 days with no complications. There was no correlation between percent liver regeneration and steatosis severity. Among recipients, 4 underwent redo-transplantation and 6 died, with no association with degree of steatosis. 52 recipients (36%) fulfilled criteria for EAD (driven by INR), with no difference in hepatic steatosis between groups. MRI-PDFF reliably predicted donor outcomes. Living donors with no or mild steatosis based on MRI-PDFF (ie, <20%) and meeting other criteria for donation can expect favorable post-surgical outcomes, including liver regeneration. Recipients had a low rate of death or retransplantation with no association between mild hepatic steatosis and EAD.

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.

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.

Interleukin-33 / Cyclin D1 imbalance in severe liver steatosis predicts susceptibility to ischemia reperfusion injury

Transplanting donor livers with severe macrosteatosis is associated with increased risk of primary non-function (PNF). The purpose of this study was to identify steatosis-driven biomarkers as a predisposition to severe liver damage and delayed recovery following ischemia reperfusion injury. Wistar rats were fed a methionine- and choline-deficient (MCD) diet for up to three weeks to achieve severe macrosteatosis (>90%). Animals underwent diet withdrawal to control chow and/or underwent ischemia reperfusion and partial hepatectomy injury (I/R-PHx) and reperfused out to 7 days on control chow. For animals with severe macrosteatosis, hepatic levels of IL-33 decreased while Cyclin D1 levels increased in the absence of NF-κB p65 phosphorylation. Animals with high levels of nuclear Cyclin D1 prior to I/R-PHx either did not survive or had persistent macrosteatosis after 7 days on control chow. Survival 7 days after I/R-PHx fell to 57% which correlated with increased Cyclin D1 and decreased liver IL-33 levels. In the absence of I/R-PHx, withdrawing the MCD diet normalized IL-33, Cyclin D1 levels, and I/R-PHx survival back to baseline. In transplanted grafts with macrosteatosis, higher Cyclin D1 mRNA expression was observed. Shifts in Cyclin D1 and IL-33 expression may identify severely macrosteatotic livers with increased failure risk if subjected to I/R injury. Clinical validation of the panel in donor grafts with macrosteatosis revealed increased Cyclin D1 expression corresponding to delayed graft function. This pre-surgical biomarker panel may identify the subset of livers with increased susceptibility to PNF.

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.

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.

The potential role of vascular alterations and subsequent impaired liver blood flow and hepatic hypoxia in the pathophysiology of non-alcoholic steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) covers a spectrum of disease ranging from steatosis to steatohepatitis (NASH) and fibrosis, but the underlying pathophysiological mechanisms remain largely unknown. As there is currently no approved pharmacological therapy and the prevalence of NAFLD keeps increasing, understanding of its pathophysiology is crucial. We hypothesise that vascular alterations in early NAFLD play a role in the progression of the disease by inducing an increased intrahepatic vascular resistance and consequently relative hypoxia in the liver. Evidence of the detrimental effects of hypoxia in NAFLD has already been observed in liver surgery, where the outcomes of steatotic livers after ischaemia-reperfusion are worse than in healthy livers, and in obstructive sleep apnoea, which is an independent risk factor of NAFLD. Moreover, early histological damage in NAFLD is situated in the pericentral zone, which is also the first zone to be affected by a decreased oxygen tension because of the unique hepatic vacsular anatomy that causes the pericentral oxygen tension to be the lowest. Angiogenesis is also a characteristic of NAFLD, driven by hypoxia-induced mechanisms, as demonstrated in both animal models and in humans with NAFLD. Relative hypoxia is most probably induced by impaired blood flow to the liver, caused by increased intrahepatic vascular resistance. An increased intrahepatic vascular resistance early in the development of disease has been convincingly demonstrated in several animal models of NAFLD, whereas an increased portal pressure, a consequence of increased intrahepatic vascular resistance, has been proven in patients with NAFLD. Animal studies demonstrated a decreased intrahepatic effect of vasodilators and an increased reactivity to vasoconstrictors that results in an increased intrahepatic vascular resistance, thus the presence of a functional component. Pharmacological products that target vasoregulation can hence improve the intrahepatic vascular resistance and this might prevent or reverse progression of NAFLD, representing an important therapeutic option to study. Some of the drugs currently under evaluation in clinical trials for NASH have interesting properties related to the hepatic vasculature. Some other interesting drugs have been tested in animal models but further study in patients with NAFLD is warranted. In summary, in this paper we summarise the evidence that leads to the hypothesis that an increased intrahepatic vascular resistance and subsequent parenchymal hypoxia in early NAFLD is an important pathophysiological driving mechanism for the progression of the disease.

Ex situ machine perfusion as a tool to recondition steatotic donor livers: Troublesome features of fatty livers and the role of defatting therapies. A systematic review

Long-standing research has shown that increased lipid content in donor livers is associated with inferior graft outcomes posttransplant. The global epidemic that is obesity has increased the prevalence of steatosis in organ donors, to the extent that it has become one of the main reasons for declining livers for transplantation. Consequently, it is one of the major culprits behind the discrepancy between the number of donor livers offered for transplantation and those that go on to be transplanted. Steatotic livers are characterized by poor microcirculation, depleted energy stores because of an impaired capacity for mitochondrial recovery, and a propensity for an exaggerated inflammatory response following reperfusion injury culminating in poorer graft function postoperatively. Ex situ machine perfusion, currently a novel method in graft preservation, is showing great promise in providing a tool for the recovery and reconditioning of marginal livers. Hence, reconditioning these steatotic livers using machine perfusion has the potential to increase the number of liver transplants performed. In this review, we consider the problematic issues associated with fatty livers in the realm of transplantation and discuss pharmacological and nonpharmacological options that are being developed to enhance recovery of these organs using machine perfusion and defatting strategies.

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.

Perspective review on solid-organ transplant: needs in point-of-care optical biomarkers

Solid-organ transplant is one of the most complex areas of modern medicine involving surgery. There are challenging opportunities in solid-organ transplant, specifically regarding the deficiencies in pathology workflow or gaps in pathology support, which may await alleviations or even de novo solutions, by means of point-of-care, or point-of-procedure optical biomarkers. Focusing the discussions of pathology workflow on donor liver assessment, we analyze the undermet need for intraoperative, real-time, and nondestructive assessment of the donor injuries (such as fibrosis, steatosis, and necrosis) that are the most significant predictors of post-transplant viability. We also identify an unmet need for real-time and nondestructive characterization of ischemia or irreversible injuries to the donor liver, earlier than appearing on morphological histology examined with light microscopy. Point-of-procedure laparoscopic optical biomarkers of liver injuries and tissue ischemia may also facilitate post-transplant management that is currently difficult for or devoid of pathological consultation due to lack of tools. The potential and pitfalls of point-of-procedure optical biomarkers for liver assessment are exemplified in breadth for steatosis. The more general and overarching challenges of point-of-procedure optical biomarkers for liver transplant pathology, including the shielding effect of the liver capsule that was quantitated only recently, are projected. The technological and presentational benchmarks that a candidate technology of point-of-procedure optical biomarkers for transplant pathology must demonstrate to motivate clinical translation are also foreseen.

Liver cell therapy: is this the end of the beginning?

The prevalence of liver diseases is increasing globally. Orthotopic liver transplantation is widely used to treat liver disease upon organ failure. The complexity of this procedure and finite numbers of healthy organ donors have prompted research into alternative therapeutic options to treat liver disease. This includes the transplantation of liver cells to promote regeneration. While successful, the routine supply of good quality human liver cells is limited. Therefore, renewable and scalable sources of these cells are sought. Liver progenitor and pluripotent stem cells offer potential cell sources that could be used clinically. This review discusses recent approaches in liver cell transplantation and requirements to improve the process, with the ultimate goal being efficient organ regeneration. We also discuss the potential off-target effects of cell-based therapies, and the advantages and drawbacks of current pre-clinical animal models used to study organ senescence, repopulation and regeneration.

Liver biopsy in assessment of extended criteria donors

The safety and liver utilization with prerecovery liver biopsy (PLB) in extended criteria liver donors are unclear. We conducted a retrospective cohort study in 1323 brain death donors (PLB = 496) from 3 organ procurement organizations (OPOs). Outcomes were complications, preempted liver recovery (PLR), and liver transplantation (LT). Additional analyses included liver-only and propensity score-matched multiorgan donor subgroups. PLB donors were older (57 versus 53 years; P < 0.001). Hepatitis C antibody positivity (14.3% versus 9.6%, P = 0.01) and liver-only donors (42.6% versus 17.5%; P < 0.001) were more prevalent. The PLB cohort had fewer complications (31.9% versus 42.3%; P < 0.001). In the PLB cohort, PLR was significantly higher (odds ratio [OR], 3.45; 95% confidence interval [CI], 2.42-4.92) and LT lower (OR, 0.69; 95% CI, 0.52-0.91). In liver-only and propensity score-matched multiorgan donor subgroups, PLR was significantly higher (OR, 1.76; 95% CI, 1.06-2.94 and OR, 2.29; 95% CI, 1.37-3.82, respectively) without a decrease in LT (OR, 0.71; 95% CI, 0.43-1.18 and OR, 0.91; 95% CI, 0.63-1.33, respectively) in PLB subgroups. In conclusion, in extended criteria liver donors, PLB is safe and decreases futile liver recovery without decreasing LT. Increased use of PLB, especially in liver-only donors, is likely to save costs to OPOs and transplant centers and improve efficiencies in organ allocation. Liver Transplantation 24 182-191 2018 AASLD.

Fast Chromotrope Aniline Blue Special Stain Is a Useful Tool to Assess Fibrosis on Liver Biopsy During Transplantation

BACKGROUND

Assessment of potential liver allograft donors with frozen sections has clinical relevant consequences for the transplant recipient. Several clinical risk factors have been identified that increase the risk of transplantation failure and it is critical for the pathologist to become familiar with the histologic criteria for donor liver suitability. In this setting an accurate and reliable assessment of fibrosis is crucial. We sought to report the value of the rapid chromotrope aniline blue stain (CAB) in a transplantation clinical work-flow for scoring liver fibrosis.

MATERIALS AND METHODS

Twenty consecutive intraoperative donor liver biopsy specimens were evaluated by a pathologist at the Transplant Pathology Board Room, AOUI Verona, during 24-hour on-call service. The stage of fibrosis was evaluated according to Ishak score ranging from 0 to 6 (absent to cirrhosis) using hematoxylin and eosin stain (H&E) plus rapid CAB special stain. After a 3-week washout period, only the slides stained with H&E were re-assessed for fibrosis stage by the same pathologist blinded to donor patient data.

RESULTS

Combination H&E-CAB staging fibrosis score was higher in 20%, lower in 10%, and the same in 70% of biopsy specimens as determined using only H&E stain alone. Rapid CAB stain takes 20 minutes longer than H&E stain alone.

CONCLUSIONS

CAB staining may be performed on frozen tissue from liver biopsy during a transplantation process without a significant delay in diagnosis. Combination H&E-CAB staining improves sensibility of interpretation of fibrosis.

Developing a donation after cardiac death risk index for adult and pediatric liver transplantation

AIM

To identify objective predictive factors for donor after cardiac death (DCD) graft loss and using those factors, develop a donor recipient stratification risk predictive model that could be used to calculate a DCD risk index (DCD-RI) to help in prospective decision making on organ use.

METHODS

The model included objective data from a single institute DCD database (2005-2013, n = 261). Univariate survival analysis was followed by adjusted Cox-regressional hazard model. Covariates selected via univariate regression were added to the model via forward selection, significance level P = 0.3. The warm ischemic threshold was clinically set at 30 min. Points were given to each predictor in proportion to their hazard ratio. Using this model, the DCD-RI was calculated. The cohort was stratified to predict graft loss risk and respective graft survival calculated.

RESULTS

DCD graft survival predictors were primary indication for transplant (P = 0.066), retransplantation (P = 0.176), MELD > 25 (P = 0.05), cold ischemia > 10 h (P = 0.292) and donor hepatectomy time > 60 min (P = 0.028). According to the calculated DCD-RI score three risk classes could be defined of low (DCD-RI < 1), standard (DCD-RI 2-4) and high risk (DCD-RI > 5) with a 5 years graft survival of 86%, 78% and 34%, respectively.

CONCLUSION

The DCD-RI score independently predicted graft loss (P < 0.001) and the DCD-RI class predicted graft survival (P < 0.001).

Organ Procurement Organization Survey of Practices and Beliefs Regarding Prerecovery Percutaneous Liver Biopsy in Donation After Neurologic Determination of Death

BACKGROUND

Prerecovery liver biopsy (PLB) allows histological evaluation of the organ before procurement. The opinions and what factors might influence PLB use within Organ Procurement Organizations (OPOs) are unknown.

METHODS

A survey instrument was distributed by the Association of OPOs to the clinical directors of all 58 OPOs. Descriptive statistics were calculated. Results were also stratified based on OPO characteristics.

RESULTS

Forty-nine (84.5%) of 58 OPOs responded to the survey; 40 (81.6%) of 49 currently perform PLB. This did not vary based on land mass, population, livers discarded, transplanted, donor age, or recipient MELD scores. Donor age, obesity, alcohol abuse, hepatitis serology, liver only donor, imaging results, and transplant center request were the most common indications for PLB in over 80% of OPOs. The median rate of performance is 5% to 10% of donors. Most use interventional radiologists to perform and the donor hospital pathologist/s to interpret PLB. Most OPOs believe PLBs are safe, reliable, useful, and performed often enough. Most say they did not believe they are easy to obtain. Beliefs were mixed regarding accuracy. The topics likely to influence PLB use were utility and accuracy of PLB, and availability of staff to perform PLB. OPOs that perform PLB more often were more likely to have favorable opinions of safety and pathologist availability, and more influenced by safety, reliability, availability, and a national consensus on the use of PLB.

CONCLUSIONS

Considerable variability exists in the use of PLB. Additional information on the utility, accuracy, and safety of PLB are needed to optimize its use.

Retraction: "Safety limitations of fatty liver transplantation can be extended to 40%: Experience of a single centre in China", by Yu Z., Yu S., Zhang L., Feng X., Zhang M., et al

The above article, published online on 13 October 2016 in Wiley OnlineLibrary (wileyonlinelibrary.com), has been retracted by agreement between the journal Editor in Chief, Mario U. Mondelli, and John Wiley & Sons Ltd. see accompanying Editorial Note It has come to the attention of the Editors that the article may have contained data referring to the use of organs retrieved from executed prisoners and not from donors after cardiac death (DCD), thus breaching international organ donation ethical standards. Further information is contained in the accompanying Editorial link. REFERENCE Yu Z, Sun Z, Yu S, et al. Safety limitations of fatty liver transplantation can be extended to 40%: experience of a single centre in China. Liver Int. 2016; doi: 10.1111/liv.13244.

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.

In vivo assessment of diet-induced rat hepatic steatosis development by percutaneous single-fiber spectroscopy detects scattering spectral changes due to fatty infiltration

This study explores percutaneous single-fiber spectroscopy (SfS) of rat livers undergoing fatty infiltration. Eight test rats were fed a methionine-choline-deficient (MCD) diet, and four control rats were fed a normal diet. Two test rats and one control rat were euthanized on days 12, 28, 49, and 77 following initiation of the diet, after percutaneous SfS of the liver under transabdominal ultrasound guidance. Histology of each set of the two euthanized test rats showed mild and mild hepatic lipid accumulations on day 12, moderate and severe on day 28, severe and mild on day 49, and moderate and mild on day 77. Livers with moderate or higher lipid accumulation generally presented higher spectral reflectance intensity when compared to lean livers. Livers of the eight test rats on day 12, two of which had mild lipid accumulation, revealed an average scattering power of 0.37±0.14 in comparison to 0.07±0.14 for the four control rats (p<0.01 ). When livers of the test rats with various levels of fatty infiltration were combined, the average scattering power was 0.36±0.15 0.36±0.15 in comparison to 0.14±0.24 of the control rats (0.05<p<0.1). Increasing lipid accumulation in concentration and size seemed to cause an increase of the scattering power prior to increasing total spectral reflectance.

Utility of pre-procurement bedside liver biopsy in the deceased extended-criteria liver donor

INTRODUCTION

The Indiana Organ Procurement Organization (IOPO) utilizes preoperative bedside liver biopsies in certain extended-criteria donors (ECDs), obtained by the on-site coordinator, to determine the utility of pursuing donation. This study reports the clinical and financial outcomes for this management strategy.

METHODS

All bedside liver biopsies obtained in ECDs over a five-yr period were reviewed. Study variables included the following: indication for biopsy, biopsy results, taking the case to the operating room, transplantation of the donor liver, and graft survival. All biopsies were processed at a single university center.

RESULTS

There were 110 donors biopsied. Primary indications included the following: old age (29%), extensive/current alcohol abuse (26%), hepatitis C-positive serology (21%), obesity (25%), and severely elevated liver function enzymes (18%). Biopsy results demonstrated a potentially transplantable liver in 73 cases (66%), all of whom were taken to the OR (while 37 ruled out for donation based upon liver biopsy [34%]). Of all biopsied livers, 49 ultimately were transplanted (45%). Intra-operative decisions included the following: transplant 51/73 (70%), surgeon decision to exclude 20/73 (27%), nonuse due to finding of malignancy two (3%).

CONCLUSIONS

Bedside liver biopsy may be a valuable tool to determine the utility in pursuing donation in ECDs, particularly with liver-only donors.

Effects of steatosis on hepatic hemodynamics in patients with metabolic syndrome

The aim of our study was to assess the hemodynamic changes in hepatic and splenic circulation using B-mode ultrasonography and color Doppler ultrasonography, in a population of patients with metabolic syndrome divided with respect to the presence or absence of steatosis diagnosed by ultrasonography. One hundred forty-one patients were included in the study. The severity of non-alcoholic fatty liver disease was classified as mild, moderate or severe. Visceral fat thickness, longitudinal diameter of the spleen, diameter of the portal vein, mean maximum portal vein flow velocity, hepatic artery and splenic artery resistivity indexes and hepatic vein flow phasicity were measured. Non-alcoholic fatty liver disease was detected in 114 of 141 patients, with a prevalence of 80.8%. Patients with steatosis had significantly greater diameters of the portal vein, longitudinal diameters of the spleen, visceral fat thickness and hepatic artery and splenic artery resistivity indexes, whereas their portal vein flow velocities were significantly lower. Non-alcoholic fatty liver disease severity correlated positively with diameter of the portal vein, longitudinal diameter of the spleen and visceral fat thickness and negatively with hepatic artery and splenic artery resistivity indexes and reduced hepatic vein flow phasicity. Our patients with metabolic syndrome and non-alcoholic fatty liver disease had a flattened hepatic vein flow phasicity, greater portal vein diameter, reduction in portal vein flow velocity and intrahepatic arterial vasodilation. The vasodilation of the intrahepatic arterial system was likely activated both by the effect of insulin resistance and as a physiologic adaptation to restore hepatic flow. The increase in spleen volume might be related to the organomegaly typical of obese patients.

Noninvasive assessment of macrovesicular liver steatosis in cadaveric donors based on computed tomography liver-to-spleen attenuation ratio

Fatty liver disease, including liver steatosis, is a major health problem worldwide. In liver transplantation, macrovesicular steatosis in donor livers is a major cause of graft failure and remains difficult to assess. On one hand, several imaging modalities can be used for the assessment of liver fat, but liver biopsy, which is still considered the gold standard, may be difficult to perform in this context. On the other hand, computed tomography (CT) is commonly used by teams managing cadaveric donors to assess donors and to minimize the risk of complications in recipients. The purpose of our study was to validate the use of CT as a semiquantitative method for assessing macrovesicular steatosis in cadaveric donors with liver biopsy as a reference standard. A total of 109 consecutive cadaveric donors were included between October 2009 and May 2011. Brain death was diagnosed according to French legislation. Liver biopsy and then CT were performed on the same day to determine the degree of macrovesicular steatosis. All liver biopsies and CT scans were analyzed in a double-blinded fashion by a senior pathologist and a senior radiologist, respectively. For CT, we used the liver-to-spleen (L/S) attenuation ratio, which is a validated method for determining 30% or greater steatosis in living liver donors. Fourteen of 109 biopsies exhibited macrovesicular steatosis > 30% upon histologic analysis. A receiver operating characteristic curve was generated for the L/S ratio to identify its ability to predict significant steatosis, which was defined as >30%. A cutoff value of 0.9 for the CT L/S ratio provided a sensitivity of 79% and a specificity of 97% to detect significant steatosis.

Donor information based prediction of early allograft dysfunction and outcome in liver transplantation

BACKGROUND & AIMS

Poor initial graft function was recently newly defined as early allograft dysfunction (EAD) [Olthoff KM, Kulik L, Samstein B, et al. Validation of a current definition of early allograft dysfunction in liver transplant recipients and analysis of risk factors. Liver Transpl 2010; 16: 943]. Aim of this analysis was to evaluate predictive donor information for development of EAD.

METHODS

Six hundred and seventy-eight consecutive adult patients (mean age 51.6 years; 60.3% men) who received a primary liver transplantation (LT) (09/2003-12/2011) were included. Standard donor data were correlated with EAD and outcome by univariable/multivariable logistic regression and Cox proportional hazards to identify prognostic donor factors after adjustment for recipient confounders. Estimates of relevant factors were utilized for construction of a new continuous risk index to develop EAD.

RESULTS

38.7% patients developed EAD. 30-day survival of grafts with and without EAD was 59.8% and 89.7% (P < 0.0001). 30-day survival of patients with and without EAD was 68.5% and 93.1% (P < 0.0001) respectively. Donor body mass index (P = 0.0112), gGT (P = 0.0471), macrosteatosis (P = 0.0006) and cold ischaemia time (CIT) (P = 0.0031) were predictors of EAD. Internal cross validation showed a high predictive value (c-index = 0.622).

CONCLUSIONS

Early allograft dysfunction correlates with early results of LT and can be predicted by donor data only. The newly introduced risk index potentially optimizes individual decisions to accept/decline high risk organs. Outcome of these organs might be improved by shortening CIT.

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.

Quantification of degree of steatosis in extended criteria donor grafts with standardized histologic techniques: implications for graft survival

The gap between the availability of livers from organ donors and the increased demand has led many centers to apply strategies to reduce this deficit. Splitting of cadaveric organs for use in 2 recipients; domino transplantation; and organs from living donors, non-heart-beating donors, and extended-criteria donors (ECDs) are all currently used in orthotopic liver transplantation (OLT). Fatty changes in the donor liver are a risk factor for poor function after OLT; however, the presence of steatosis, frequently present in livers from ECDs, does not exclude the use of these organs. Since January 2000 at our institution, we observed 39 steatotic grafts that were stratified istologically as follows: low steatosis, 5% to 15%; mild steatosis, 16% to 30%; moderate steatosis, 31% to 60%; and severe steatosis (>60%). Histologic techniques can enable identification of the type of fatty change as macrovesicular and microvesicular. These alterations have different effects on primary nonfunction and primary dysfunction. Fifteen grafts, all with severe or moderate, macrovesicular changes were discarded. Twenty-four fatty grafts with low to moderate steatosis were utilized for transplant. Sections from 2 liver biopsies (1 wedge in the left lobe and 1 needle in the right lobe) were stained with hematoxylin-eosin, Masson trichrome, Gomori reticulin, and oil red O. The OLT was performed only in patients with a MELD (Model for End-Stage Liver Disease) score lower than 27. The rate of primary dysfunction was 12.5%, and of primary nonfunction 8.4%. The 6-month graft survival for all fatty livers was 80%. We encourage the careful use of grafts with low to moderate steatosis in recipients without additional risks.

Challenges of recurrent hepatitis C in the liver transplant patient

Cirrhosis secondary to hepatitis C virus (HCV) is a very common indication for liver transplant. Unfortunately recurrence of HCV is almost universal in patients who are viremic at the time of transplant. The progression of fibrosis has been shown to be more rapid in the post-transplant patients than in the transplant naïve, hence treatment of recurrent HCV needs to be considered for all patients with documented recurrent HCV. Management of recurrent HCV is a challenging situation both for patients and physicians due to multiple reasons as discussed in this review. The standard HCV treatment with pegylated interferon and Ribavarin can be considered in these patients but it leads to a lower rate of sustained virologic clearance than in the non-transplanted population. Some of the main challenges associated with treating recurrent HCV in post-transplant patients include the presence of cytopenias; need to monitor drug-drug interactions and the increased incidence of renal compromise. In spite of these obstacles all patients with recurrent HCV should be considered for treatment since it is associated with improvement in survival and a delay in fibrosis progression. With the arrival of direct acting antiviral drugs there is renewed hope for better outcomes in the treatment of post-transplant HCV recurrence. This review evaluates current literature on this topic and identifies challenges associated with the management of post-transplant HCV recurrence.

Quantification of hepatic steatosis: a comparison of the accuracy among multiple magnetic resonance techniques

BACKGROUND AND AIM

Magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) are important diagnostic tools for the non-invasive assessment of hepatic steatosis (HS). This study was conducted to compare different magnetic resonance (MR) techniques and correlate the MR findings with histological and intracellular lipid density findings.

METHODS

In this institutional review board-approved, Health Insurance Portability and Accountability Act-compliant prospective study, 60 patients scheduled for liver resection were included in this study. Fat fraction in the non-tumorous liver parenchyma was estimated using double-echo MRI, triple-echo MRI (TE-MRI), and MRS. HS was defined by the histologic steatosis percentage (HSP), and intrahepatocellular triglyceride density (IHTGD) of the surgical specimen used as the reference standard. Imaging quantification results were evaluated using Pearson's correlation. Lin's concordance coefficient and Bland-Altman 95% limits of agreement were used to evaluate the concordance of IHTGDs estimated by the three MR techniques. The diagnostic performance was compared using receiver operating characteristic curve analysis.

RESULTS

HS assessed by TE-MRI and MRS had a stronger relationship with HS assessed by HSP and IHTGD. The TE-MRI method had the highest concordance correlation coefficients (ρ = 0.881) and percentage (95%, 57/60) within the Bland-Altman 95% limits of agreement. Receiver operating characteristic curve analysis for diagnosing > 5% HSP showed significantly larger area under the curve (0.9783) for TE-MRI than for double-echo MRI (0.8773, P = 0.0121).

CONCLUSIONS

Among the three MR techniques, TE-MRI and MRS may be the preferred techniques for non-invasive assessment of HS.

A critical analysis of early death after adult liver transplants

INTRODUCTION

The 15% mortality rate of liver transplant recipients at one yr may be viewed as a feat in comparison with the waiting list mortality, yet it nonetheless leaves room for much improvement. Our aim was to critically examine the mortality rates to identify high-risk periods and to incorporate cause of death into the analysis of post-transplant survival.

METHODS

We performed a retrospective analysis on United Network for Organ Sharing data for all adult recipients of liver transplants from January 1, 2002 to October 31, 2011. Our analysis included multivariate logistic regression where the primary outcome measure was patient death of 49,288 recipients.

RESULTS

The highest mortality rate by day post-transplant was on day 0 (0.9%). The most significant risk factors were as follows: for one-d mortality from technical failure, intensive care unit admission odds ratio (OR 3.2); for one-d mortality from graft failure, warm ischemia >75 min (OR 5.6); for one-month mortality from infection, a previous transplant (OR 3.3); and for one-month mortality from graft failure, a previous transplant (OR 3.7).

CONCLUSION

We found that the highest mortality rate after liver transplantation is within the first day and the first month post-transplant. Those two high-risk periods have common, as well as different, risk factors for mortality.

Hepatic ischemia and reperfusion injury: effects on the liver sinusoidal milieu

Ischemia-reperfusion injury is an important cause of liver damage occurring during surgical procedures including hepatic resection and liver transplantation, and represents the main underlying cause of graft dysfunction post-transplantation. Cellular and biochemical processes occurring during hepatic ischemia-reperfusion are diverse and complex, and include the deregulation of the healthy phenotype of all liver cellular components. Nevertheless, a significant part of these processes are still unknown or unclear. The present review aims at summarizing the current knowledge in liver ischemia-reperfusion, but specifically focusing on liver cell phenotype and paracrine interaction deregulations. Moreover, the most updated therapeutic strategies including pharmacological, genetic and surgical interventions, as well as some of the scientific controversies in the field will be described. Finally, the importance of considering the subclinical situation of liver grafts when translating basic knowledge to the bedside is discussed.

Assessment of hepatic steatosis by transplant surgeon and expert pathologist: a prospective, double-blind evaluation of 201 donor livers

An accurate clinical assessment of hepatic steatosis before transplantation is critical for successful outcomes after liver transplantation, especially if a pathologist is not available at the time of procurement. This prospective study investigated the surgeon's accuracy in predicting hepatic steatosis and organ quality in 201 adult donor livers. A steatosis assessment by a blinded expert pathologist served as the reference gold standard. The surgeon's steatosis estimate correlated more strongly with large-droplet macrovesicular steatosis [ld-MaS; nonparametric Spearman correlation coefficient (rS ) = 0.504] versus small-droplet macrovesicular steatosis (sd-MaS; rS  = 0.398). True microvesicular steatosis was present in only 2 donors (1%). Liver texture criteria (yellowness, absence of scratch marks, and round edges) were mainly associated with ld-MaS (variance = 0.619) and were less associated with sd-MaS (variance = 0.264). The prediction of ≥30% ld-MaS versus <30% ld-MaS was excellent when liver texture criteria were used (accuracy = 86.2%), but it was less accurate when the surgeon's direct estimation of the steatosis percentage was used (accuracy = 75.5%). The surgeon's quality grading correlated with the degree of ld-MaS and the surgeon's steatosis estimate as well as the incidence of poor initial function and primary nonfunction. In conclusion, the precise estimation of steatosis remains challenging even in experienced hands. Liver texture characteristics are more helpful in identifying macrosteatotic organs than the surgeon's actual perception of steatosis. These findings are especially important when histological assessment is not available at the donor's hospital.

Increased intrahepatic resistance in severe steatosis: endothelial dysfunction, vasoconstrictor overproduction and altered microvascular architecture

Non-alcoholic fatty liver disease can progress to steatohepatitis and fibrosis, and is also associated with impaired liver regeneration. The pathophysiology remains elusive. We recently showed that severe steatosis is associated with an increase in portal pressure, suggesting liver flow impairment. The objective of this study is to directly assess total intrahepatic resistance and its potential functional and structural determinants in an in situ perfusion model. Male Wistar rats fed a control (n = 30) or a methionine-choline-deficient (MCD) diet (n = 30) for 4 weeks were compared. Liver tissue and serum analysis, in vivo haemodynamic measurements, in situ perfusion experiments and vascular corrosion casts were performed. The MCD group showed severe steatosis without inflammation or fibrosis on histology. Serum levels and liver tissue gene expression of interleukin (IL)-6, tumour necrosis factor-α, IL-1β and interferon-γ, liver tissue myeloperoxidase activity and liver immunohistochemistry with anti-CD68 and anti-α smooth muscle actin were comparable between groups, excluding significant inflammation. Flow-pressure curves were significantly different between groups for all flows (slope values: 0.1636 ± 0.0605 mm Hg/ml/min in controls vs 0.7270 ± 0.0408 mm Hg/ml/min in MCD-fed rats, P < 0.001), indicating an increased intrahepatic resistance, which was haemodynamically significant (portocaval pressure gradient 2.2 ± 1.1 vs 8.2 ± 1.3 mm Hg in controls vs MCD, P<0.001). Dose-response curves to acetylcholine were significantly reduced in MCD-fed rats (P < 0.001) as was the responsiveness to methoxamine (P<0.001). Vascular corrosion casts showed a replacement of the regular sinusoidal anatomy by a disorganized pattern with multiple interconnections and vascular extensions. Liver phosphorylated endothelial NO synthase (eNOS)/eNOS and serum nitrite/nitrate were not increased in severe steatosis, whereas liver thromboxane synthase expression, liver endothelin-1 (ET-1) expression and serum andothelin-1 concentration were significantly increased. Severe steatosis induces a haemodynamically significant increase in intrahepatic resistance, which precedes inflammation and fibrogenesis. Both functional (endothelial dysfunction and increased thromboxane and ET-1 synthesis) and structural factors are involved. This phenomenon might significantly contribute to steatosis-related disease.

Assessment of liver transplant donor biopsies for steatosis using frozen section: accuracy and possible impact on transplantation

Background

Pre-transplant frozen section evaluation for macrovesicular steatosis has long been used as a guide for donor liver utility, but may not agree with the permanent section evaluation. This study sought to evaluate the accuracy of frozen section in an active transplant service.

Methods

Retrospective review of cases where frozen section analysis was undertaken to assess percent macrovesicular steatosis was performed, comparing the frozen section diagnosis to the final diagnosis.

Results

Ninety-six cases were available for review. In 7 of these cases (7%), the difference between the two slides was significant; that is, the difference between the two slides may have contributed to a change in clinical management at a cutoff of 30%.

Conclusions

Clinicians need to be aware that accuracy is satisfactory in experienced hands but some discrepancies may occur.

Keywords

Liver; Steatosis; Pathology

Frozen section diagnosis in donor liver biopsies: observer variation of semiquantitative and quantitative steatosis assessment

Donor livers are not generally accepted for liver transplantation if intraoperative frozen section histology on wedge biopsies provides evidence for more severe steatosis. In this reliability study, assessment of steatosis in donor liver biopsies by different approaches (frozen sections vs. paraffin sections; macrovesicular steatosis vs. microvesicular steatosis), different observers, and different evaluation methods (conventional microscopy vs. point grid analysis on digital microphotographs) was compared. One hundred twenty consecutive donor liver biopsies were investigated. Intraoperative diagnosis was made on hematoxylin and eosin (H&E)-stained frozen sections. The residual portion of each biopsy was analyzed later on H&E-, diastase-resistant PAS-, and Elastica van Gieson-stained paraffin sections. Microvesicular steatosis and macrovesicular steatosis were classified semiquantitatively into 5 % steps. Additionally, point grid counting was applied on ten digital microphotographs per slide. The values for steatosis revealed a wide range of data between 0 and 70 or 85 % (mean values, 12.0-18.3 %), considering all types of specimens. The results of the two observers were highly correlated for macrovesicular steatosis (r ≥ 0.925) and for microvesicular steatosis (r ≥ 0.880). The values for macrovesicular and microvesicular steatosis, however, showed poor correlation (r ≤ 0.581). The rate of agreement between the two observers ranged between 84.2 and 95.8 % (κ, 0.763-0.937), depending on the threshold setting. For point grid analysis, significantly lower mean values and ranges for both types of steatosis compared to conventional histopathology were found (p < 0.001). Comparing the results of point grid analysis with those of conventional histopathology, a relatively loose correlation was found (r, 0.581-0.779). Intraoperative histology remains a reliable and highly relevant method for the assessment of steatosis in liver donor grafts. It represents one important component in the decision-finding whether or not a donor liver should be accepted and should possibly be combined with results of preoperative computed tomography imaging. Considering our data, macrovesicular and microvesicular steatosis should be analyzed separately due to the limited correlation between them.

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.

Hepatic steatosis and normothermic perfusion-preliminary experiments in a porcine model

BACKGROUND

Steatotic livers are increasingly common in the donor population. Cold storage of steatotic livers exacerbates ischemia-reperfuson injury and risks primary nonfunction and recipient death. Normothermic preservation avoids prolonged cooling of the organ and may be well suited to the preservation and resuscitation of damaged livers. By ex vivo normothermic perfusion, it may be possible to preserve and improve steatotic livers, so that transplantation is a viable option.

METHODS

In a porcine model, streptozotocin was used to induce a hyperglycemic, ketotic state that, together with a high fat diet, resulted in mild hepatic steatosis at 5 weeks. A blood-based oxygenated ex vivo normothermic preservation system was then used to compare extended preservation of normal and mildly steatotic porcine livers at physiological pressures and flows. Serial liver biopsies were stained with Oil Red O, a specialist triglyceride stain, and were analyzed using custom-designed image analysis to quantify the degree of lipid deposition.

RESULTS

Steatotic livers were capable of correcting the perfusate base excess and maintaining factor V and bile production and showed markers of liver injury comparable with normal livers. Steatotic livers had a significantly higher urea production and required no glucose support. Preliminary results suggest that prolonged normothermic perfusion results in a reduction in steatosis.

CONCLUSIONS

This study suggests that steatotic livers can be successfully preserved using normothermic preservation for prolonged periods and that normothermic preservation facilitates a reduction in hepatic steatosis. Further studies are now needed including transplantation of steatotic livers after normothermic preservation.

Hepatic steatosis is not always a contraindication for cadaveric liver transplantation

BACKGROUND

Macrovesicular steatosis is assumed to be an important risk factor for early allograft dysfunction (EAD) after orthotopic liver transplantation (OLT).

AIM

To evaluate the impact of steatosis in combination with other risk factors on the outcome of OLT.

METHODS

The degree of steatosis was analysed in 165 consecutive OLTs and was classified by histological examination as non (M0), mild (<30%, M1), moderate (30-60%, M2) or severe steatosis (>60%, M3). Recipients were analysed for EAD.

RESULTS

EAD was observed in 28% of patients with M0, 26% with M1, 53% with M2 and 73% with M3 (P < 0.001). Patients with EAD had a significantly shorter graft survival after liver transplantation (P = 0.005) but did not correlate with survival. In multivariate regression analysis, the grade of steatosis, donating after cardiocirculatory death (DCD) grafts and duration of cold ischaemia time were significantly associated with EAD (P < 0.001, P = 0.01 and P = 0.001, respectively).

CONCLUSION

Livers with severe (M3) steatosis from DCD donors, combined with a prolonged CIT have a high risk for developing EAD which is correlated with shorter graft survival. Therefore M3 livers should only be considered for OLT in selected recipients without the presence of additional risk factors.

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.