Development and Characterization of a Hybrid Bioartificial Liver Using Primary Hepatocytes Entrapped in a Basement Membrane Matrix

For the development of a bioartificial liver (BAL) support device, it is most important to establish highly differentiated liver cells cultured at high density. When rat hepatocytes were cultured on a basement membrane matrix, Engelbreth-Holm-Swarm (EHS) gel, their rates of albumin secretion were very high, as measured by ELISA, and these high rates were maintained for more than three weeks of culturing. This level of activity greatly exceeded that of hepatocytes cultured on a plastic substratum, poly-N-p-vinylbenzyl-d-lactonamide (PVLA), on a single layer of collagen, or in a collagen sandwich culture. In an in vitro perfusion experiment, rat hepatocytes rapidly and completely removed ammonia from Eagle's MEM supplemented with 0.2 mM NH₄Cl, although ammonia levels of the medium serially increased in modules containing HepG2 cells. A hybrid liver support system was developed and consisted of plasma perfusion through porous hollow fiber modules inoculated with 10 billion porcine hepatocytes entrapped in EHS gel. This system was applied to pigs with ischemic liver failure 8 hr after creation of a portocaval shunt and hepatic devascularization. In animals treated with the BAL support system, blood bicarbonate levels were increased immediately after treatment, and hemodynamic stability was improved. In control pigs, on the other hand, blood bicarbonate levels and blood pressure remained low. Plasma levels of ammonia and lactate decreased in pigs treated with the BAL device, but not in control animals. These results indicate that primary hepatocytes outperform HepG2 cells as a source of biotransformation functions in a BAL system and that the use of a BAL support device in combination with a hollow fiber module and hepatocytes entrapped in EHS gel has potential advantages for clinical use in patients with fulminant hepatic failure.     

Effect of extracorporeal bioartificial liver support system on fulminant hepatic failure rabbits

AIM To evaluate the possibility of using cultured human hepatocytes as a bridge between bioartificial liver and liver transplantation. METHODS In this experiment, the efficacy of extracorporeal bioartificial liver support system (EBLSS) consisting of spheriodal human liver cells and cultured hepatocytes supernatant was assessed in vivo using galactosamine induced rabbit model of fulminant hepatic failure. RiESULTS There was no difference of survival between the two groups of rabbits, but in the supported rabbits serum alanine aminotransferase, total bilirubin and creatinine were significantly lower and hepatocyte necrosis was markedly milder than those in control animals. In addition, a good viability of human liver cells was noted after the experiment. CONCLUSION EBLSS plays a biologic role in maintaining and compensating the function of the liver.     

Mannose‐binding lectin and the prognosis of fulminant hepatic failure caused by HBV infection

Abstract: Background/Aims: The mannose‐binding lectin (MBL) gene was reported to play an important role in determining the clinical outcome of persistent hepatitis B virus (HBV) infection. We investigated serum MBL concentrations and MBL gene mutations to determine whether they were related to the prognosis of patients with fulminant hepatic failure (FHF) caused by HBV infection. Methods: We investigated serum MBL concentrations and MBL gene mutations in 43 HBV‐infected Japanese patients with FHF and 260 HBsAg‐negative healthy controls. Serum MBL concentrations were measured by an enzyme‐linked immunosorbent assay, and mutations in the MBL gene were analysed by nested PCR and direct DNA sequencing. Results: Only a mutation in codon 54 of the MBL gene was found. The frequency of this mutation in nonsurvivors (40%, 8/20) was higher than in survivors (13%, 3/23), and the difference was slightly significant (p = 0.043). The H allele frequency in survivors (70.5%, 31/44) was higher than in nonsurvivors (39.5%, 15/38) (p = 0.0048). Because of these factors the mean serum MBL concentration in survivors, 1.61 μg/ml (range 0.3–3.86), was significantly higher than in nonsurvivors, 0.79 μg/ml (range 0.04–1.51) (p < 0.0001). The likelihood ratio for nonsurvival was 0 for over 2.0 μg/ml, 0.67 for 1.0–2.0 μg/ml, and 2.24 for 0–1.0 μg/ml. Conclusions: The mutation in codon 54 of the MBL gene tended to be higher in nonsurvivors than in survivors. The H allele frequency (high producing allele in H/Y) in survivors was higher than that in nonsurvivors. High levels of serum MBL correlated with the survival of patients with FHF due to HBV infection. Serum MBL may be useful as a predictive factor for the survival of patients with FHF caused by HBV.     

Efficacy of short‐term dexamethasone therapy in acute‐on‐chronic pre‐liver failure

Aim: Acute‐on‐chronic pre‐liver failure (pre‐ACLF) is defined as a severe acute episode of chronic hepatitis B characterized by serum bilirubin of 171 µmol/L or more, alanine aminotransferase of five times or more the upper limit of normal and prothrombin activity of more than 40%, having a potential for progression to acute‐on‐chronic liver failure (ACLF). This study is to evaluate the efficacy of short‐term dexamethasone in pre‐ACLF. Methods: One hundred and seventy patients were assigned to dexamethasone therapy and control group at a ratio of 1:2. For the two groups, we compared biochemical indicators, the incidence of ACLF and mortality. The influential factors on the mortality of patients with pre‐ACLF were studied by Cox proportional hazards models. Results: The significantly lower incidence of ACLF and higher survival rate were observed in patients on dexamethasone therapy (8.9%, 96.4%, respectively) than in control patients (70.2%, 52.6%, respectively; P < 0.001). Dexamethasone treatment was an independent factor influencing the survival rate (P < 0.001, odds ratio = 0.055, 95% confidence interval = 0.013–0.225). During 4 weeks of treatment, serum bilirubin levels of survival patients were significantly lower in the dexamethasone group than control group. Conclusion: Five‐day dexamethasone therapy is effective in improving the liver function and survival rate of patients with pre‐ACLF.     

Classification of the etiologies of acute liver failure in Japan: A report by the Intractable Hepato‐Biliary Diseases Study Group of Japan

The Intractable Liver Diseases Study Group of Japan, supported by the Ministry of Health, Labor and Welfare, established novel diagnostic criteria for “acute liver failure” in 2011. In these criteria, patients without histological findings of hepatitis are included in the disease entity of “acute liver failure”, as in Europe and the USA. In this report, classification criteria for the etiologies of “acute liver failure” in Japan are proposed.     

Hepatic stimulator substance administration ameliorates liver regeneration in an animal model of fulminant hepatic failure and encephalopathy

Abstract: Aims/Background: Hepatic stimulator substance (HSS) is a liver‐specific growth factor implicated in hepatocellular proliferation and hepatoprotection in models of acute liver injury. In the present study, we examined the effect of exogenous HSS administration on liver proliferating capacity and survival outcome in an experimental animal model of fulminant hepatic failure (FHF) and encephalopathy, induced by repeated injections of thioacetamide (TAA) in rats. Methods: Fulminant hepatic failure was induced in adult male Wistar rats by three consecutive intraperitoneal injections of TAA (400 mg/kg of body weight), at 24 h time intervals. The animals received intraperitoneally either a saline solution or HSS (50 mg protein/kg of body weight), 2 h after the second and third TAA injections. The animals were killed at 6, 12 and 18 h post the last injection of TAA. Results: Levels of liver enzymes and urea in serum, blood ammonia values, liver histology, stage of hepatic encephalopathy and survival were statistically significantly improved in TAA‐intoxicated and HSS‐treated rats compared to TAA‐intoxicated and saline‐treated ones. Furthermore, HSS ameliorated liver regenerative indices – DNA biosynthesis, thymidine kinase activity and hepatocyte mitotic activity – in a statistically significant manner. Conclusions: Our data suggest the beneficial effect of HSS administration in this animal model of FHF and encephalopathy, supporting evidence for a possible use of HSS as supportive therapy, by increasing hepatocellular proliferation, in management of FHF.     

Increased serum and hepatic tissue levels of interleukin-18 in patients with fulminant hepatic failure

BACKGROUND: Fulminant hepatic failure is a serious clinical condition associated with a high mortality rate. Interleukin (IL)-18 is a pro-inflammatory cytokine that is associated with several inflammatory diseases. The purpose of the present paper was therefore to investigate whether IL-18 is elevated in patients with fulminant hepatic failure. METHODS: Serum levels of IL-18 were measured in patients with fulminant hepatic failure before and after liver transplantation. Native liver tissue samples were collected and the tissue levels of IL-18 were determined. Liver tissues were stained immunohistochemically with antihuman IL-18 antibody. The serum levels of IL-1beta, IL-6, IL-8, IL-12, interferon-gamma, and tumor necrosis factor-alpha were also determined in patients with fulminant hepatic failure before and after liver transplantation. RESULTS: Elevated levels of IL-18 in serum and hepatic tissue were observed in patients with fulminant hepatic failure. Native liver tissue samples were immunohistochemically positive for IL-18. Interleukin-18 levels were markedly reduced after liver replacement. No other inflammatory cytokines were substantially elevated in patients with fulminant hepatic failure. CONCLUSION: The serum levels of IL-18 levels are elevated much more than those of other cytokines in patients with fulminant hepatic failure.     

Melatonin prevents the decreased activity of antioxidant enzymes and activates nuclear erythroid 2‐related factor 2 signaling in an animal model of fulminant hepatic failure of viral origin

Abstract: This work was undertaken to investigate whether treatment with melatonin prevents oxidative stress and changes in the expression and activity of factor erythroid 2‐related factor 2 (Nrf2)‐mediated antioxidant enzymes in an animal model of fulminant hepatic failure of viral origin. Rabbits were experimentally infected with 2 × 10⁴ hemagglutination units of a rabbit hemorrhagic disease virus (RHDV) isolate and received melatonin at two concentrations of 10 mg/kg and 20 mg/kg at 0, 12 and 24 hr postinfection. Blood transaminases, blood lactate dehydrogenase, liver concentration of thiobarbituric reactive acid substances and the liver oxidized to reduced glutathione ratio significantly increased at 36 hr postinfection in infected animals. Significant decreases were found in the mRNA levels and in the liver activities of Mn‐superoxide dismutase, glutathione peroxidase and glutathione‐S‐transferase in infected rabbits. These effects were prevented by melatonin administration in a concentration‐dependent manner. Melatonin treatment was not accompanied by changes in protein levels of Kelch‐like ECH‐associating protein 1 (Keap1) but resulted in an increased protein expression of Nrf2 in the cytoplasm and the nucleus, which was confirmed by the results of Nrf2 immunostaining. Nuclear extracts from livers of melatonin‐treated rats displayed an enhanced antioxidant responsive element (ARE)‐binding activity of Nrf2. Our results suggest a potential hepatoprotective role of melatonin in fulminant hepatic failure, partially mediated through the abrogation of oxidative stress and the prevention of the decreased activity of antioxidant enzymes via the Nrf2 pathways.