Artificial liver support in pigs with acetaminophen-induced acute liver failure

Stem Cell-Based Strategies: The Future Direction of Bioartificial Liver Development

Acute liver failure (ALF) results from severe liver damage or end-stage liver disease. It is extremely fatal and causes serious health and economic burdens worldwide. Once ALF occurs, liver transplantation (LT) is the only definitive and recommended treatment; however, LT is limited by the scarcity of liver grafts. Consequently, the clinical use of bioartificial liver (BAL) has been proposed as a treatment strategy for ALF. Human primary hepatocytes are an ideal cell source for these methods. However, their high demand and superior viability prevent their widespread use. Hence, finding alternatives that meet the seed cell quality and quantity requirements is imperative. Stem cells with self-renewing, immunogenic, and differentiative capacities are potential cell sources. MSCs and its secretomes encompass a spectrum of beneficial properties, such as anti-inflammatory, immunomodulatory, anti-ROS (reactive oxygen species), anti-apoptotic, pro-metabolomic, anti-fibrogenesis, and pro-regenerative attributes. This review focused on the recent status and future directions of stem cell-based strategies in BAL for ALF. Additionally, we discussed the opportunities and challenges associated with promoting such strategies for clinical applications.

Research progress on rodent models and its mechanisms of liver injury

The liver is the most important organ for biological transformation in the body and is crucial for maintaining the body's vital activities. Liver injury is a serious pathological condition that is commonly found in many liver diseases. It has a high incidence rate, is difficult to cure, and is prone to recurrence. Liver injury can cause serious harm to the body, ranging from mild to severe fatty liver disease. If the condition continues to worsen, it can lead to liver fibrosis and cirrhosis, ultimately resulting in liver failure or liver cancer, which can seriously endanger human life and health. Therefore, establishing an rodent model that mimics the pathogenesis and severity of clinical liver injury is of great significance for better understanding the pathogenesis of liver injury patients and developing more effective clinical treatment methods. The author of this article summarizes common chemical liver injury models, immune liver injury models, alcoholic liver injury models, drug-induced liver injury models, and systematically elaborates on the modeling methods, mechanisms of action, pathways of action, and advantages or disadvantages of each type of model. The aim of this study is to establish reliable rodent models for researchers to use in exploring anti-liver injury and hepatoprotective drugs. By creating more accurate theoretical frameworks, we hope to provide new insights into the treatment of clinical liver injury diseases.

A simple and efficient strategy for cell-based and cell-free-based therapies in acute liver failure: hUCMSCs bioartificial liver

Acute liver failure (ALF) is a life-threatening condition. Cell-based and cell-free-based therapies have proven to be effective in treating ALF; however, their clinical application is limited by cell tumorigenicity and extracellular vesicle (EV) isolation in large doses. Here, we explored the effectiveness and mechanism of umbilical cord mesenchymal stem cells (hUCMSCs)-based bioartificial liver (hUCMSC-BAL), which is a simple and efficient strategy for ALF. D-galactosamine-based pig and mouse ALF models were used to explore the effectiveness of hUCMSC-BAL and hUCMSC-sEV therapies. Furthermore, high-throughput sequencing, miRNA transcriptome analysis, and western blot were performed to clarify whether the miR-139-5p/PDE4D axis plays a critical role in the ALF model in vivo and in vitro. hUCMSC-BAL significantly reduced inflammatory responses and cell apoptosis. hUCMSC-sEV significantly improved liver function in ALF mice and enhanced the regeneration of liver cells. Furthermore, hUCMSC-sEV miRNA transcriptome analysis showed that miR-139-5p had the highest expression and that PDE4D was one of its main target genes. The sEV miR-139-5p/PDE4D axis played a role in the treatment of ALF by inhibiting cell apoptosis. Our data indicate that hUCMSC-BAL can inhibit cytokine storms and cell apoptosis through the sEV miR-139-5p/PDE4D axis. Therefore, we propose hUCMSC-BAL as a therapeutic strategy for patients with early ALF.

Normothermic Ex Vivo Liver Platform Using Porcine Slaughterhouse Livers for Disease Modeling

Metabolic and toxic liver disorders, such as fatty liver disease (steatosis) and drug-induced liver injury, are highly prevalent and potentially life-threatening. To allow for the study of these disorders from the early stages onward, without using experimental animals, we collected porcine livers in a slaughterhouse and perfused these livers normothermically. With our simplified protocol, the perfused slaughterhouse livers remained viable and functional over five hours of perfusion, as shown by hemodynamics, bile production, indocyanine green clearance, ammonia metabolism, gene expression and histology. As a proof-of-concept to study liver disorders, we show that an infusion of free fatty acids and acetaminophen results in early biochemical signs of liver damage, including reduced functionality. In conclusion, the present platform offers an accessible system to perform research in a functional, relevant large animal model while avoiding using experimental animals. With further improvements to the model, prolonged exposure could make this model a versatile tool for studying liver diseases and potential treatments.

A bioartificial transgenic porcine whole liver expressing human proteins alleviates acute liver failure in pigs

BACKGROUND

Preventing heterologous protein influx in patients is important when using xenogeneic bioartificial livers (BALs) to treat liver failure. The development of transgenic porcine livers synthesizing human proteins is a promising approach in this regard. Here, we evaluated the safety and efficacy of a transgenic porcine liver synthesizing human albumin (hALB) and coagulation factor VII (hFVII) within a bioartificial system.

METHODS

Tibetan miniature pigs were randomly subjected to different interventions after surgery-induced partially ischemic liver failure. Group A (n = 4) was subjected to basic treatment; group B (n = 4) was to standard medical treatment and wild-type porcine BAL perfusion, and group C (n = 2) was to standard medical treatment and transgenic BAL perfusion. Biochemical parameters, coagulation status, survival time, and pathological changes were determined. Expressions of hALB and hFVII were detected using immunohistochemistry and enzyme-linked immunosorbent assays.

RESULTS

The survival time in group A was 9.75 ± 1.26 days; this was shorter than that in both perfused groups, in which all animals reached an endpoint of 12 days (P = 0.006). Ammonia, bilirubin, and lactate levels were significantly decreased, whereas albumin and fibrinogen levels were increased after perfusion (all P < 0.05). hALB and hFVII were detected in transgenic BAL-perfused pig serum and ex vivo in the liver tissues.

CONCLUSIONS

The humanized transgenic pig livers could synthesize and secrete hALB and hFVII ex vivo in a whole organ-based bioartificial system, while maintaining their metabolism, detoxification, transformation, and excretion functions, which were comparable to those observed in wild-type porcine livers. Therefore, the use of transgenic bioartificial whole livers is expected to become a new approach in treating acute liver failure.

Metabolism and Effects on Endogenous Metabolism of Paracetamol (Acetaminophen) in a Porcine Model of Liver Failure

The metabolic fate, toxicity, and effects on endogenous metabolism of paracetamol (acetaminophen, APAP) in 22 female Landrace cross large white pigs were evaluated in a model of acute liver failure (ALF). Anesthetized pigs were initially dosed at 250 mg/kg via an oroduodenal tube with APAP serum concentrations maintained above 300 mg/l using maintenance doses of 0.5–4 g/h until ALF. Studies were undertaken to determine both the metabolic fate of APAP and its effects on the endogenous metabolic phenotype of ALF in using ¹H NMR spectroscopy. Increased concentrations of citrate combined with pre-ALF increases in circulating lactate, pyruvate, and alanine in plasma suggest mitochondrial dysfunction and a switch in hepatic energy metabolism to glycolysis in response to APAP treatment. A specific liquid chromatography-tandem mass spectrometry assay was used to quantify APAP and metabolites. The major circulating and urinary metabolite of APAP was the phenolic glucuronide (APAP-G), followed by p-aminophenol glucuronide (PAP-G) formed from N-deacetylated APAP. The PAP produced by N-deacetylation was the likely cause of the methemoglobinemia and kidney toxicity observed in this, and previous, studies in the pig. The phenolic sulfate of APAP, and the glutathione-derived metabolites of the drug were only found as minor components (with the cysteinyl conjugate detected but not the mercapturate). Given its low sulfation, combined with significant capacity for N-deacetylation the pig may represent a poor translational model for toxicology studies for compounds undergoing significant metabolism by sulfation, or which contain amide bonds which when hydrolyzed to unmask an aniline lead to toxicity. However, the pig may provide a useful model where extensive amide hydrolysis is seen for drugs or environmental chemicals in humans, but not in, eg, the rat and dog which are the preclinical species normally employed for safety assessment.

Differential hepatic features presenting in Wilson disease-associated cirrhosis and hepatitis B-associated cirrhosis

BACKGROUND

Cirrhosis is a chronic late stage liver disease associated with hepatitis viruses, alcoholism, and metabolic disorders, such as Wilson disease (WD). There are no clear markers or clinical features that define cirrhosis originating from these disparate origins. We hypothesized that cirrhosis is not one disease and cirrhosis of different etiology may have differential clinical hepatic features.

AIM

To delineate the liver features between WD-associated cirrhosis and hepatitis B-associated cirrhosis in the Chinese population.

METHODS

In this observational study, we reviewed the medical data of consecutive inpatients who had WD-associated cirrhosis or hepatitis B-associated cirrhosis from January 2010 to August 2018, and excluded patients who had carcinoma, severe heart or pulmonary diseases, or other liver diseases. According to the etiology of cirrhosis, patients were divided into two groups: WD-associated cirrhosis group (60 patients) and hepatitis B-associated cirrhosis group (56 patients). The liver fibrosis degree, liver function indices, and portal hypertension features of these patients were compared between the two groups.

RESULTS

No inter-group differences were observed in the diagnostic liver fibrosis markers, however, clinical features clearly defined the origin of cirrhosis. WD-associated cirrhosis patients (16-29 years) had lower levels of alanine transaminase, aspartate transaminase, and bilirubin, lower prothrombin time, lower incidence of hepatic encephalopathy, and lower portal vein diameter (P < 0.05), compared to cirrhosis resulting from hepatitis B in older patients (45-62 years). Importantly, they had decreased risks of progression from Child-Pugh grade A to B (odds ratio = 0.046, 95% confidence interval: 0.006-0.387, P = 0.005) and of ascites (odds ratio = 0.08, 95% confidence interval: 0.01-0.48, P = 0.005). Conversely, WD-associated cirrhosis patients had a higher risk of splenomegaly (odds ratio = 4.15, 95% confidence interval: 1.38-12.45, P = 0.011).

CONCLUSION

WD-associated cirrhosis presents a higher risk of splenomegaly associated with leukopenia and thrombocytopenia, although revealing milder liver dysfunction and portal hypertension symptoms, which recommends WD patients to be monitored for associated complications.

Artificial Liver and Renal Support System for Cynomolgus Monkeys with Surgery-Induced Acute Renal Failure: A Preclinical Study

Renal dysfunction is one of the most common complications of liver cirrhosis and is associated with increased morbidity and mortality. However, no available technology can simultaneously support liver and renal function in these patients. The aim of this study was to evaluate the safety and efficacy of an artificial liver and renal support system in cynomolgus monkeys with surgery-induced ARF. The ARF model was established by ligature of bilateral renal arteries in eight cynomolgus monkeys, which were randomly divided into a treatment group (n = 4) and control group (n = 4). Biochemical indexes were determined before and after surgery. Blood endotoxin levels, biochemical indexes, and bacterial cultures were assessed at 0, 3, and 6 h during treatment. System pressures and vital signs were recorded at 1 h intervals. Pathological examination was performed after death. ARF was successfully established, based on significant elevation of biochemical indexes and pathological examination. The treatment group had significantly reduced biochemical indexes relative to the control group. Measurement of blood endotoxins and aerobic and anaerobic bacteria cultures indicated no bacterial growth. The system pressures and vital signs were stable during treatment. The results indicate that our support system for the treatment of cynomolgus monkeys with surgery-induced acute renal failure is safe and effective.

Novel D-galactosamine-induced cynomolgus monkey model of acute liver failure

AIM

To establish a simplified, reproducible D-galactosamine-induced cynomolgus monkey model of acute liver failure having an appropriate treatment window.

METHODS

Sixteen cynomolgus monkeys were randomly divided into four groups (A, B, C and D) after intracranial pressure (ICP) sensor implantation. D-galactosamine at 0.3, 0.25, 0.20 + 0.05 (24 h interval), and 0.20 g/kg body weight, respectively, was injected via the small saphenous vein. Vital signs, ICP, biochemical indices, and inflammatory factors were recorded at 0, 12, 24, 36, 48, 72, 96, and 120 h after D-galactosamine administration. Progression of clinical manifestations, survival times, and results of H&E staining, TUNEL, and Masson staining were recorded.

RESULTS

Cynomolgus monkeys developed different degrees of debilitation, loss of appetite, and jaundice after D-galactosamine administration. Survival times of groups A, B, and C were 56 ± 8.7 h, 95 ± 5.5 h, and 99 ± 2.2 h, respectively, and in group D all monkeys survived the 144-h observation period except for one, which died at 136 h. Blood levels of ALT, AST, CK, LDH, TBiL, Cr, BUN, and ammonia, prothrombin time, ICP, endotoxin, and inflammatory markers [(tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6)] significantly increased compared with baseline values in different groups (P < 0.05). Pathological results showed obvious liver cell necrosis that was positively correlated with the dose of D-galactosamine.

CONCLUSION

We successfully established a simplified, reproducible D-galactosamine-induced cynomolgus monkey model of acute liver failure, and the single or divided dosage of 0.25 g/kg is optimal for creating this model.