Modeling Principle

The Pig Acute Liver Failure Model is a SCI gold-standard large-animal pathological model of acute liver failure established by fractionated intravenous administration of D-galactosamine (D-GalN) combined with lipopolysaccharide (LPS). It accurately recapitulates full pathological characteristics of clinical acute liver failure (ALF) induced by drugs, toxins and infection, including extensive hepatocellular degeneration and necrosis, hepatic lobule structural disintegration, intrahepatic inflammatory cytokine storm, hepatic microcirculation disturbance, severe liver dysfunction, pre-hepatic encephalopathy and systemic multi-organ oxidative and inflammatory injury. It compensates for experimental defects of rodent animals with tremendous differences from humans in liver volume, hepatic metabolic pathways, portal circulation, coagulation system and liver-brain interaction mechanism.

The hepatic lobular anatomy, hepatocyte metabolic enzyme spectrum, intrahepatic immune cell typing, bile secretion rhythm, coagulation factor synthesis pathway and hepatic detoxification metabolic pathway of Bama minipigs are highly homologous to humans. D-GalN competitively consumes hepatocellular uridine triphosphate, blocks hepatic RNA and protein synthesis, and directly induces hepatocyte endoplasmic reticulum stress and apoptosis. LPS activates the TLR4/NF-κB pathway of hepatic Kupffer cells, massively releases pro-inflammatory factors including TNF-α, IL-1β, IL-6 and IFN-γ, triggers intrahepatic inflammatory storm, destroys hepatic sinusoidal endothelial barrier, and aggravates hepatic microcirculation congestion and hypoxic hepatocellular necrosis. Synergistic cascade injury induced by two agents leads to explosive elevation of transaminases, bilirubin accumulation, sharp coagulation disorder and elevated blood ammonia within a short period, and gradually progresses to typical acute liver failure accompanied by systemic oxidative stress disorder and secondary renal and pulmonary injury. This model fully recapitulates the classic pathogenic cascade of human acute liver failure: hepatocyte metabolic blockade-excessive innate immune activation-intrahepatic inflammatory storm-massive hepatocellular necrosis-hepatic function collapse-systemic multi-organ injury.

Minipigs possess sufficient liver volume, stable portal hemodynamics and controllable liver injury gradient without spontaneous liver diseases. It can clearly distinguish three-stage lesions including early hepatic injury stress stage, peak inflammatory necrosis stage and stable terminal acute liver failure stage, serving as a standardized large-animal gold-standard model for translational research on acute liver failure pathogenesis, artificial liver support system, hepatoprotective drugs, anti-inflammatory and antioxidant preparations, and intervention targets of hepatic encephalopathy.

Modeling Success Criteria

Macroscopic Gross Hepatic and General Phenotype

Animals in blank control group were active with normal food intake and clear light yellow urine. The liver was ruddy, soft and intact in lobulation without congestion, punctate necrosis or swelling. At 24 h terminal point, animals in model group showed listlessness, drowsiness and dull response, significantly reduced food and water intake, and dark brown tea-colored urine. Diffuse liver swelling and dark red congestion could be observed by dissection, with a large number of gray-white coagulative necrotic foci on hepatic surface and blurred hepatic lobule texture. The macroscopic phenotype of acute toxic hepatic necrosis was typical with extremely significant difference from blank group, confirming preliminary successful construction of acute liver failure model.

Quantitative Biochemical Gold-Standard Indexes of Serum

Serum ALT, AST, TBIL and blood ammonia in model group were extremely significantly higher than blank group; albumin ALB decreased sharply, prothrombin time PT was remarkably prolonged; serum pro-inflammatory factors TNF-α, IL-1β, IL-6 and IFN-γ were explosively upregulated; accumulation of MDA in hepatic tissues and serum increased while antioxidant activity of SOD decreased significantly, fully matching the core biochemical diagnostic characteristics of clinical acute liver failure: massive hepatocellular necrosis, hepatic dysfunction, coagulation disorder, hyperammonemia, systemic inflammatory storm and collapsed oxidative stress.

Hepatic Histopathological Characteristics

Combined HE, CD68 and TUNEL staining of hepatic tissues showed characteristic temporal pathological injuries of acute liver failure:

1. Early stage at 6 h after administration: mild hepatocellular edema, a small amount of punctate apoptosis, a small number of activated Kupffer cells infiltrated in hepatic sinusoids with intact hepatic lobule structure;
2. Inflammatory peak stage at 12 h after administration: diffuse balloon-like degeneration of hepatocytes, massive aggregation of CD68-positive Kupffer cells in hepatic sinusoids, patchy hepatocellular apoptosis and necrosis, and initial disintegration of hepatic lobule structure;
3. Terminal stage at 24 h after administration: extensive massive coagulative necrosis of hepatic lobules with complete dissolution and disappearance of hepatocytes in necrotic areas, severe degeneration of residual hepatocytes, massive inflammatory cell infiltration in portal area and congested dilated hepatic sinusoids, which perfectly recapitulates graded pathological injuries of drug/endotoxin-induced acute liver failure in humans.

Core Inflammatory, Apoptotic and Oxidative Stress Pathway Indexes

The hepatic TLR4/NF-κB pathway of model group was persistently overactivated with massive release of downstream pro-inflammatory factors; hepatocyte endoplasmic reticulum stress and mitochondrial apoptotic pathways were abnormally upregulated with sharp surge of TUNEL-positive apoptotic cells; systemic antioxidant pathway was inhibited with massive accumulation of oxygen free radicals. It accurately conforms to the complete pathogenic mechanism synergistically induced by D-GalN/LPS: hepatocyte metabolic blockade-excessive Kupffer cell activation-inflammatory storm-extensive hepatocyte apoptosis and necrosis-acute liver failure, serving as core academic criterion for confirming successful modeling.

Model Advantages

This model is a well-recognized exclusive large-animal gold-standard model for D-GalN combined LPS-induced acute liver failure in hepatology SCI field. It rapidly and stably forms complete acute liver failure phenotypes highly homologous to humans including explosive hepatocellular necrosis, inflammatory storm, coagulation failure and hyperammonemia within 24 h. The hepatic metabolism, immune cell composition, coagulation and ammonia metabolic pathways of minipigs are close to human body, with uniform and consistent hepatic injury sequence and liver function deterioration gradient, extremely low intra-group data dispersion and far higher reproducibility than rodents. The modeling mechanism simulates explosive hepatic injury induced by superposition of clinical drugs, toxins and infection, without one-sidedness caused by simple surgery or single toxin induction. It is suitable for preclinical large-animal pharmacodynamic verification of artificial liver, intravenous hepatoprotective preparations, new anti-inflammatory and antioxidant drugs and liver-targeted carriers. Multiple dynamic blood collections can be performed on single animal with sufficient hepatic tissue samples, and synchronous multi-organ sampling can evaluate secondary pulmonary and renal injury induced by liver damage. It has extremely high clinical transformation credibility and high recognition in high-score SCI journals of hepatology, gastroenterology and critical care medicine, suitable for National Natural Science Foundation, master/doctor project opening, graduation thesis of gastroenterology/critical care medicine and translational medical research on liver failure supportive therapy.

Research Applications

The Pig Acute Liver Failure Model is corely applied to basic research on D-GalN-blocked hepatocyte nucleic acid metabolism, LPS-activated Kupffer cell TLR4 inflammatory pathway, intrahepatic inflammatory cytokine storm, extensive hepatocyte apoptosis and necrosis, coagulation collapse and prodromal injury of hyperammonemic hepatic encephalopathy. It is specially used for screening and evaluating intravenous hepatoprotective small molecules, natural extracts, artificial liver adsorption media, liver-targeted nano-preparations and critical anti-inflammatory treatment regimens with effects of alleviating hepatocellular degeneration and necrosis, inhibiting intrahepatic inflammatory storm, scavenging hepatic oxygen free radicals, maintaining synthetic coagulation function, reducing blood ammonia and relieving prodromal symptoms of hepatic encephalopathy. It is widely adopted for excavation of pathogenic immune targets of acute liver failure, elucidation of interactive regulatory network between intrahepatic inflammation and apoptosis, and large-animal preclinical in-vivo verification of liver failure prevention drugs and support systems, serving as a scarce and essential standardized large-animal gold-standard model in the fields of critical liver disease, gastroenteric pharmacology and artificial liver regenerative medicine.

pig acute liver failure model, D-GalN/LPS induced liver injury, massive hepatocellular necrosis, intrahepatic inflammatory storm, multi-organ dysfunction, preclinical liver support drug evaluation