Donor fatty (steatotic) liver allografts in orthotopic liver transplantation

Necroptosis in Hepatosteatotic Ischaemia-Reperfusion Injury

While liver transplantation remains the sole treatment option for patients with end-stage liver disease, there are numerous limitations to liver transplantation including the scarcity of donor livers and a rise in livers that are unsuitable to transplant such as those with excess steatosis. Fatty livers are susceptible to ischaemia-reperfusion (IR) injury during transplantation and IR injury results in primary graft non-function, graft failure and mortality. Recent studies have described new cell death pathways which differ from the traditional apoptotic pathway. Necroptosis, a regulated form of cell death, has been associated with hepatic IR injury. Receptor-interacting protein kinase 3 (RIPK3) and mixed-lineage kinase domain-like pseudokinase (MLKL) are thought to be instrumental in the execution of necroptosis. The study of hepatic necroptosis and potential therapeutic approaches to attenuate IR injury will be a key factor in improving our knowledge regarding liver transplantation with fatty donor livers. In this review, we focus on the effect of hepatic steatosis during liver transplantation as well as molecular mechanisms of necroptosis and its involvement during liver IR injury. We also discuss the immune responses triggered during necroptosis and examine the utility of necroptosis inhibitors as potential therapeutic approaches to alleviate IR injury.

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.

Comparative Study on the Cytoprotective Effects of Activated Protein C Treatment in Nonsteatotic and Steatotic Livers under Ischemia-Reperfusion Injury

Activated protein C (APC) has cytoprotective effects on liver ischemia-reperfusion injury (IRI). However, it is unclear whether APC is beneficial in steatotic liver IRI. We compared the cytoprotective effects of APC in nonsteatotic and steatotic liver IRI.

METHODS

Mice fed either normal diets (ND mice) or high fat diets (HF mice), were treated with APC or saline (control) and were performed 60 min partial IRI. Moreover, primary steatotic hepatocytes were either untreated or treated with APC and then incubated with H2O2.

RESULTS

APC significantly reduced serum transaminase levels and the inflammatory cells infiltration compared with control at 4 h in ND mice and at 24 h in HF mice. APC inhibited sinusoidal endothelial injury in ND mice, but not in HF mice. In contrast, APC activated adenosine monophosphate-activated protein kinase (AMPK) phosphorylation in HF mice, but not in ND mice. In the in vitro study, APC significantly increased AMPK phosphorylation, ATP concentration, and survival rates of hepatocytes compared with control.

CONCLUSION

During IRI in normal liver, APC attenuated initial damage by inhibiting inflammatory cell infiltration and sinusoidal endothelial injury, but not in steatotic liver. However, in steatotic liver, APC might attenuate late damage via activation of AMPK.

Recipient and perioperative risk factors associated with liver transplant graft outcomes

BACKGROUND

Orthotopic liver transplantation (OLT) is currently considered to be the ultimate form of therapy for most patients with end-stage liver diseases. The identification of recipient and various perioperative factors that may affect the graft outcomes is critical. This study sought to analyze the preoperative and perioperative factors associated with graft outcomes in our institute.

METHODS

This retrospective study of liver transplanted patients from January 2002 to December 2009 determined the incidence of 2 forms of primary dysfunction (PDF): Primary nonfunction (PNF) and initial poor function (IPF).

RESULTS

The 97 posttransplant patients included in the study had an average age of 52.74 years. The majority of indications for OLT were hepatitis B and/or C cirrhosis, alcoholic cirrhosis, and hepatocellular carcinoma. The incidence of PDF was 31.9% (31/97) with 7.2% (7/97) PNF and 24.7% (24/97) IPF. Additionally, we observed 68.1% (66/97) to display immediate function (IF). Warm ischemic time (WIT) and operative time were significantly longer in the PDF compared with the IF group. The logistic regression model showed a WIT of >45 minutes to be a risk factor leading to PDF (odds ratio, 11.74; P<.05). An operative time of >6 hours and operative blood loss of >2 L were possible risk factors.

CONCLUSION

Prolonged WIT (>45 minutes) was the only significant risk factor among other established parameters for graft function. Nevertheless, reduced operative times and blood loss may improve the outcomes of OLT.

Liver transplantation using University of Wisconsin or Celsior preserving solutions in the portal vein and Euro-Collins in the aorta

INTRODUCTION

Orthotopic liver transplantation (OLT) is today the gold standard treatment of the end-stage liver disease. Different solutions are used for graft preservation. Our objective was to compare the results of cadaveric donor OLT, preserved with the University of Wisconsin (UW) or Celsior solutions in the portal vein and Euro-Collins in the aorta.

METHODS

We evaluated retrospectively 72 OLT recipients, including 36 with UW solution (group UW) and 36 with Celsior (group CS). Donors were perfused in situ with 1000 mL UW or Celsior in the portal vein of and 3000 mL of Euro-Collins in the aortia and on the back table managed with 500 mL UW or Celsior in the portal vein, 250 mL in the hepatic artery, and 250 mL in the biliary duct. We evaluated the following variables: donor characteristics, recipient features, intraoperative details, reperfusion injury, and steatosis via a biopsy after reperfusion. We noted grafts with primary nonfunction (PNF), initial poor function (IPF), rejection episodes, biliary duct complications, hepatic artery complications, re-OLT, and recipient death in the first year after OLT.

RESULTS

The average age was 33.6 years in the UW group versus 41 years in the CS group (P = .048). There was a longer duration of surgery in the UW group (P = .001). The other recipient characteristics, ischemia-reperfusion injury, steatosis, PNF, IPF, rejection, re-OLT, and recipient survival were not different. Stenosis of the biliary duct occured in 3 (8.3%) cases in the UW group and 8 (22.2%) in the CS (P = .19) with hepatic artery thrombosis in 4 (11.1%) CS versus none in the UW group (P = .11).

CONCLUSION

Cadaveric donor OLT showed similar results with organs preserved with UW or Celsior in the portal vein and Euro-Collins in the aorta.

Fluorescence spectroscopy to diagnose hepatic steatosis in a rat model of fatty liver

BACKGROUND

Steatosis is diagnosed on the basis of the macroscopic aspect of the liver evaluated by the surgeon at the time of organ extraction or by means of a frozen biopsy.

AIM

In the present study, the applicability of laser-induced fluorescence (LIF) spectroscopy was investigated as a method for the diagnosis of different degrees of steatosis experimentally induced in rats.

MATERIAL AND METHODS

Rats received a high-lipid diet for different periods of time. The animals were divided into groups according to the degree of induced steatosis diagnosis by histology. The concentration of fat in the liver was correlated with LIF by means of the steatosis fluorescence factor (SFF).

RESULTS

The histology classification, according to liver fat concentration was, Severe Steatosis, Moderate Steatosis, Mild Steatosis and Control (no liver steatosis). Fluorescence intensity could be directly correlated with fat content. It was possible to estimate an average of fluorescence intensity variable by means of different confidence intervals (P=95%) for each steatosis group. SFF was significantly higher in the Severe Steatosis group (P<0.001) compared with the Moderate Steatosis, Mild Steatosis and Control groups.

CONCLUSION

The various degrees of steatosis could be directly correlated with SFF. LIF spectroscopy proved to be a method capable of identifying the degree of hepatic steatosis in this animal model, and has the potential of clinical application for non-invasive evaluation of the degree of steatosis.

High preoperative recipient plasma 7beta-hydroxycholesterol is associated with initial poor graft function after liver transplantation

Oxidative stress is implicated in the pathogenesis of hepatic ischemia-reperfusion injury, a major determinant of initial poor graft function (IPGF) after orthotopic liver transplantation (OLT). We prospectively investigated the association between the recipient plasma preoperative oxidative stress and the occurrence of IPGF after deceased-donor OLT and indirectly studied the source-hepatic or extra-hepatic-of systemic oxidative stress in vivo in cirrhosis. We used a recently developed specific and sensitive mass spectrometry assay to measure 7beta-hydroxycholesterol and 7-ketocholesterol (oxysterols), markers of oxidative stress, in biological matrices. At univariate analysis, preoperative recipient 7beta-hydroxycholesterol plasma concentration was significantly higher in transplants with subsequent IPGF (n = 9) compared with those with initial good graft function (IGGF; n = 23) [mean +/- SD: 30.63 +/- 26.42 and 11.57 +/- 15.76 ng/mL, respectively] (P = 0.017). In a logistic regression model, which included also the Model for End-Stage Liver Disease (MELD) score, 7beta-hydroxycholesterol plasma concentration was an independent predictor of IPGF with an odds ratio of 1.17 (95% CI, 1.02-1.33, P = 0.028). Patients with cirrhosis (n = 32) had increased oxysterol plasma levels compared with healthy controls (n = 49); livers with cirrhosis (n = 21), however, had oxysterol content comparable with normal livers obtained from organ donors (n = 19). Oxysterols persisted elevated in plasma 1 month after OLT (n = 23). In conclusion, cirrhosis presents upregulated systemic oxidative stress likely of extrahepatic source that is associated with graft failure after OLT.

The hepatic regeneration power of mild steatotic grafts is not impaired in living-donor liver transplantation

The aim of this study was to assess histologic changes in steatotic grafts, regenerative capacity, and the outcome of steatotic grafts in living-donor liver transplantation (LDLT). Between September 2002 and February 2004, 55 cases of LDLT with a liver biopsy performed on the 10th postoperative day were enrolled. Patients were grouped according to the intraoperative histologic degree of macrovesicular steatosis (MaS) as follows: Group 1, <5% (n = 24); Group 2, 5 to 15% (n = 24); and Group 3, 15 to 30% (n = 7). The intraoperative microscopic findings and the findings on the 10th postoperative day were compared. Immunohistochemistry was performed using antibody of proliferating cell nuclear antigen (PCNA) and Ki-67 to assess the regeneration power of grafts on the 10th postoperative day. The histologic degree of MaS on postoperative day 10 decreased from 5.22 +/- 1.04% (mean +/- standard deviation) to 2.17 +/- 1.90 in Group 2 (P < .001) and from 21.4 +/- 8.02 to 4.43 +/- 2.70 in Group 3 (P = .003). The number of positively stained hepatocytes in 10 high power fields was 48.0 +/- 17.1, 53.8 +/- 14.4, and 51.5 +/- 4.1 in each group by PCNA (P = .681), and 24.0 +/- 14.0, 25.5 +/- 11.8, and 21.6 +/- 6.8 by Ki-67 (P = .825), respectively. No primary graft nonfunction (PNF) or delayed graft function (DGF) occurred. Major complications were comparable among groups. In conclusion, in LDLT, steatosis disappeared immediately after transplantation and hepatic regeneration power was not impaired in grafts with less than 30% of MaS. Furthermore, a mildly steatotic graft did not increase the risk of graft dysfunction or morbidity in LDLT.

Preharvest donor hyperoxia predicts good early graft function and longer graft survival after liver transplantation

A total of 44 donor/recipient perioperative and intraoperative variables were prospectively analyzed in 89 deceased-donor liver transplantations classified as initial good graft function (IGGF) or initial poor graft function (IPGF) according to a scoring system based on values obtained during the 1st 72 postoperative hours from the serum alanine aminotransferase (ALT) concentration, bile output, and prothrombin activity. The IGGF compared with the IPGF group showed: 1) longer graft (P = .002) and patient (P = .0004) survival; 2) at univariate analysis, a higher (mean [95% confidence interval]) preharvest donor arterial partial pressure of oxygen (PaO(2)) (152 [136-168] and 104 [91-118] mmHg, respectively; P = .0008) and arterial hemoglobin oxygen saturation (97.9 [97.2-98.7] and 96.7 [95.4-98.0]%, respectively; P = .0096), a lower percentage of donors older than 65 years (13 and 33%, respectively; P = .024), a lower percentage of donors treated with noradrenaline (16 and 41%, respectively; P = .012). At multivariate analysis, IGGF was associated positively with donor PaO(2) and negatively with donor age greater than 65 years and with donor treatment with noradrenaline. Independently from the grouping according to initial graft function, graft survival was longer when donor PaO(2) was >150 mmHg than when donor PaO(2) was < or =150 mmHg (P = .045). In conclusion, preharvest donor hyperoxia predicts IGGF and longer graft survival.

Effect of ischaemic preconditioning on hepatic oxygenation, microcirculation and function in a rat model of moderate hepatic steatosis

IPC (ischaemic preconditioning) may protect the steatotic liver, which is particularly susceptible to I/R (ischaemia/reperfusion) injury. Hepatic steatosis was induced in Sprague-Dawley rats with a high-cholesterol (2%) diet for 12 weeks after which rats were subjected to I/R (ischaemia/reperfusion; 45 min of lobar ischaemia followed by 2 h of reperfusion). Rats were divided into three study groups (n=6 each) receiving: (i) sham laparotomy alone, (ii) I/R, and (iii) IPC (5 min of ischaemia, followed by 10 min of reperfusion) before I/R. Hepatic extra- and intra-cellular oxygenation and HM (hepatic microcirculation) were measured with near-infrared spectroscopy and laser Doppler flowmetry respectively. Plasma liver enzymes and hepatic tissue ATP were measured as markers of liver injury. Histology showed moderate-grade steatosis in the livers. At the end of 2 h of reperfusion, I/R significantly decreased extra- and intra-cellular oxygenation concomitant with a failure of recovery of HM (21.1+/-14.4% of baseline; P<0.001 compared with sham animals). IPC increased intracellular oxygenation (redox state of the copper centre of cytochrome oxidase; P<0.05 compared with rats receiving I/R alone) and flow in HM (70.9+/-17.1% of baseline; P<0.001 compared with rats receiving I/R alone). Hepatocellular injury was significantly reduced with IPC compared with I/R injury alone (alanine aminotransferase, 474.8+/-122.3 compared with 5436.3+/-984.7 units/l respectively; P<0.01; aspartate aminotransferase, 630.8+/-76.9 compared with 3166.3+/-379.6 units/l respectively; P<0.01]. In conclusion, IPC has a hepatoprotective effect against I/R injury in livers with moderate steatosis. These data may have important clinical implications in liver surgery and transplantation.

Clinical experience gained from the use of 120 steatotic donor livers for orthotopic liver transplantation

Steatosis of the donor liver is known to impact on patient and allograft outcome after orthotopic liver transplantation (OLT). The aim of this study is to evaluate the effect of increasing grades of cadaveric donor liver steatosis on recipient outcome. Between January, 1986 and December, 2000, 120 OLTs were performed with 72 mild, 25 moderate, and 23 severe steatotic donor livers. Donors of steatotic livers were more likely to be older (P =.001) and have died of intracerebral haemorrhage than donors of nonsteatotic livers. Initial poor graft function (IPF) was more common in donor livers with either moderate or severe steatosis than in donor livers with mild steatosis (P =.03). Primary graft nonfunction (PNF) occurred in only 1 donor liver with severe steatosis. PGE1 (PGE1) usage was higher in recipients of donor livers with moderate or severe steatosis versus donor livers with mild steatosis (P =.001). Allograft loss was greater at 1 year both in the moderate and severe (P =.03) steatotic liver groups. Patient survival at 3 months and overall allograft survival both were impacted negatively by increasing grades of donor liver steatosis (P =.02, P =.03). Three-month allograft survival was reduced in the steatotic donor livers if the donor was 50+ years old (P =.033). Recipient status at OLT (P =.001) and donor steatosis (P =.046) impacted on 30 day allograft survival (multivariate analysis). In conclusion, increasing grades of donor liver steatosis were associated with worse IPF and increased PGE1 usage. There was a negative impact of steatosis on both recipient and early allograft survival.

Effect of ischemia-reperfusion injury on the microcirculation of the steatotic liver of the Zucker rat

BACKGROUND

Much discussion has been focused on the use of steatotic livers for transplantation due to the prevalence of steatosis in the potential donor liver pool (1). The aim of this study was to investigate the possibility that the microcirculation of steatotic liver is more sensitive to the ischemia-reperfusion (IR) injury than normal liver.

METHODS

The left liver lobe of obese (n=9) and lean Zucker rats (n=9) were subjected to 40 min of warm ischemia followed by 60 min of reperfusion. Fluorescent probes rhodamine 123 (Rh123), bisbenzimide (Bis), and rhodamine 6G (Rh6G) were administered for the identification by intravital fluorescence microscopy (IVFM) of mitochondrial membrane potential, hepatocyte nuclei and leukocytes, respectively before hepatic ischemia and at 15, 30, 45, and 60 min after reperfusion. Blood samples were obtained before and after 60 min of reperfusion. Liver tissue was taken at the end of experiment for histological analysis.

RESULTS

The liver of the obese rats showed prominent macro- and microvesicular fatty changes (MAFC and MIFC) and hepatocyte swelling. Under IVFM, the obese animals had significantly wider hepatic cords (23.1+/-0.8 microm) than the lean ones (15.9+/-0.5 microm) (P<0.01), whereas no significant difference in sinusoidal diameters was noted. The number of functional sinusoids significantly decreased after 30 min of reperfusion in both groups but no significant change was noted in the nucleus count throughout the experiment. Rh123 fluorescence intensity dropped significantly in the obese group after 60 min of reperfusion but not in the lean rats. Leukocyte adherence showed a significant rise after reperfusion in both groups. Plasma AST and ALT levels were 40- and 24-fold higher respectively for the obese animals after IR compared with their preischemic values, whereas the corresponding increase were 4.2- and 3.4-fold for the lean animals, respectively.

CONCLUSIONS

Our results indicate that the liver of the obese Zucker rat is steatotic and presents with an abnormal microcirculation manifested by a reduced sinusoidal density. IR led to significantly greater hepatic injury in the steatotic than in the normal liver. This injury was accompanied by a significant reduction in the functional sinusoidal density and mitochondrial membrane potential as assessed by Rh123-associated fluorescence in the steatotic liver. In conclusion, the increased sensitivity of the steatotic liver to IR injury would appear to involve both alterations in blood flow in the microcirculation and to cellular changes.

Expanding the donor pool for liver transplantation

Because of the growing shortage of donor organs, physicians and organ procurement agencies are expanding the donor pool through three mechanisms. The first mechanism is to increase the number of patients (and their families) who give consent for organ donation and thus extend the number of cadaveric livers. The second mechanism is that marginal livers, previously considered unacceptable for transplantation, are now being successfully transplanted. The third way to expand the donor pool is through advances in medical practice such as living-donor liver transplantation and split-liver transplantation.