Pharmacotoxicology of clinically-relevant concentrations of obeticholic acid in an organotypic human hepatocyte system

The roles of nuclear receptors in cholesterol metabolism and reverse cholesterol transport in nonalcoholic fatty liver disease

As the most prevalent chronic liver disease globally, NAFLD encompasses a pathological process that ranges from simple steatosis to NASH, fibrosis, cirrhosis, and HCC, closely associated with numerous extrahepatic diseases. While the initial etiology was believed to be hepatocyte injury caused by lipid toxicity from accumulated triglycerides, recent studies suggest that an imbalance of cholesterol homeostasis is of greater significance. The role of nuclear receptors in regulating liver cholesterol homeostasis has been demonstrated to be crucial. This review summarizes the roles and regulatory mechanisms of nuclear receptors in the 3 main aspects of cholesterol production, excretion, and storage in the liver, as well as their cross talk in reverse cholesterol transport. It is hoped that this review will offer new insights and theoretical foundations for the study of the pathogenesis and progression of NAFLD and provide new research directions for extrahepatic diseases associated with NAFLD.

Human cardiovascular disease model predicts xanthine oxidase inhibitor cardiovascular risk

Some health concerns are often not identified until late into clinical development of drugs, which can place participants and patients at significant risk. For example, the United States Food and Drug Administration (FDA) labeled the xanthine oxidase inhibitor febuxostat with a"boxed" warning regarding an increased risk of cardiovascular death, and this safety risk was only identified during Phase 3b clinical trials after its approval. Thus, better preclinical assessment of drug efficacy and safety are needed to accurately evaluate candidate drug risk earlier in discovery and development. This study explored whether an in vitro vascular model incorporating human vascular cells and hemodynamics could be used to differentiate the potential cardiovascular risk associated with molecules that have similar on-target mechanisms of action. We compared the transcriptomic responses induced by febuxostat and other xanthine oxidase inhibitors to a database of 111 different compounds profiled in the human vascular model. Of the 111 compounds in the database, 107 are clinical-stage and 33 are FDA-labelled for increased cardiovascular risk. Febuxostat induces pathway-level regulation that has high similarity to the set of drugs FDA-labelled for increased cardiovascular risk. These results were replicated with a febuxostat analog, but not another structurally distinct xanthine oxidase inhibitor that does not confer cardiovascular risk. Together, these data suggest that the FDA warning for febuxostat stems from the chemical structure of the medication itself, rather than the target, xanthine oxidase. Importantly, these data indicate that cardiovascular risk can be evaluated in this in vitro human vascular model, which may facilitate understanding the drug candidate safety profile earlier in discovery and development.

Seladelpar: an investigational drug for the treatment of early-stage primary biliary cholangitis (PBC)

INTRODUCTION

Generic fibrates are used off-label as add-in therapy for the management of primary biliary cholangitis (PBC) but with unproven long-term liver-related survival benefits. The recently developed fibrate, seladelpar, has shown promising results in clinical trials, but these outcomes have been previously marred by safety concerns.

AREAS COVERED

We summarize existing treatment options in PBC and evaluate current trial data for seladelpar in relation to liver biochemistry, symptomology, and safety.

EXPERT OPINION

Seladelpar leads to marked improvement in liver biochemistry and may improve symptoms. Safety concerns around liver toxicity appear to have been addressed. With likely increasing evidence compared to existing off-label fibrates, seladelpar has the potential as an attractive future second-line agent in PBC.

In vitro models for non-alcoholic fatty liver disease: Emerging platforms and their applications

Non-alcoholic fatty liver disease (NAFLD) represents a global healthcare challenge, affecting 1 in 4 adults, and death rates are predicted to rise inexorably. The progressive form of NAFLD, non-alcoholic steatohepatitis (NASH), can lead to fibrosis, cirrhosis, and hepatocellular carcinoma. However, no medical treatments are licensed for NAFLD-NASH. Identifying efficacious therapies has been hindered by the complexity of disease pathogenesis, a paucity of predictive preclinical models and inadequate validation of pharmacological targets in humans. The development of clinically relevant in vitro models of the disease will pave the way to overcome these challenges. Currently, the combined application of emerging technologies (e.g., organ-on-a-chip/microphysiological systems) and control engineering approaches promises to unravel NAFLD biology and deliver tractable treatment candidates. In this review, we will describe advances in preclinical models for NAFLD-NASH, the recent introduction of novel technologies in this space, and their importance for drug discovery endeavors in the future.

In vitro models for non-alcoholic fatty liver disease: Emerging platforms and their applications

Non-alcoholic fatty liver disease (NAFLD) represents a global healthcare challenge, affecting 1 in 4 adults, and death rates are predicted to rise inexorably. The progressive form of NAFLD, non-alcoholic steatohepatitis (NASH), can lead to fibrosis, cirrhosis, and hepatocellular carcinoma. However, no medical treatments are licensed for NAFLD-NASH. Identifying efficacious therapies has been hindered by the complexity of disease pathogenesis, a paucity of predictive preclinical models and inadequate validation of pharmacological targets in humans. The development of clinically relevant in vitro models of the disease will pave the way to overcome these challenges. Currently, the combined application of emerging technologies (e.g., organ-on-a-chip/microphysiological systems) and control engineering approaches promises to unravel NAFLD biology and deliver tractable treatment candidates. In this review, we will describe advances in preclinical models for NAFLD-NASH, the recent introduction of novel technologies in this space, and their importance for drug discovery endeavors in the future.

Modeling nonalcoholic fatty liver disease on a liver lobule chip with dual blood supply

Nonalcoholic fatty liver disease (NAFLD) has emerged as a public health concern. To date, the mechanism of NAFLD progression remains unclear, and pharmacological treatment options are scarce. Traditional animal NAFLD models are limited in helping address these problems due to interspecies differences. Liver chips are promising for modeling NAFLD. However, pre-existing liver chips cannot reproduce complex physicochemical microenvironments of the liver effectively; thus, NAFLD modeling based on these chips is incomplete. Herein, we develop a biomimetic liver lobule chip (LC) and then establish a more accurate on-chip NAFLD model. The self-developed LC achieves dual blood supply through the designed hepatic portal vein and hepatic artery and the microtissue cultured on the LC forms multiple structures similar to in vivo liver. Based on the LC, NAFLD is modeled. Steatosis is successfully induced and more importantly, changing lipid zonation in a liver lobule with the progression of NAFLD is demonstrated for the first time on a microfluidic chip. In addition, the application of the induced NAFLD model has been preliminarily demonstrated in the prevention and reversibility of promising drugs. This study provides a promising platform to understand NAFLD progression and identify drugs for treating NAFLD. STATEMENT OF SIGNIFICANCE: Liver chips are promising for modeling nonalcoholic fatty liver disease. However, on-chip replicating liver physicochemical microenvironments is still a challenge. Herein, we developed a liver lobule chip with dual blood supply, achieving self-organized liver microtissue that is similar to in vivo tissue. Based on the chip, we successfully modeled NAFLD under physiologically differentiated nutrient supplies. For the first time, the changing lipid zonation in a single liver lobule with the early-stage progression of NAFLD was demonstrated on a liver chip. This study provides a promising platform for modeling liver-related diseases.

Liver Organoids: Updates on Disease Modeling and Biomedical Applications

Liver organoids are stem cell-derived 3D structures that are generated by liver differentiation signals in the presence of a supporting extracellular matrix. Liver organoids overcome low complexity grade of bidimensional culture and high costs of in vivo models thus representing a turning point for studying liver disease modeling. Liver organoids can be established from different sources as induced pluripotent stem cells (iPSCs), embryonic stem cells (ESCs), hepatoblasts and tissue-derived cells. This novel in vitro system represents an innovative tool to deeper understand the physiology and pathological mechanisms affecting the liver. In this review, we discuss the current advances in the field focusing on their application in modeling diseases, regenerative medicine and drug discovery.

LXR-Mediated Regulation of Marine-Derived Piericidins Aggravates High-Cholesterol Diet-Induced Cholesterol Metabolism Disorder in Mice

Reported as two antirenal cell carcinoma (RCC) drug candidates, marine-derived compounds piericidin A (PA) and glucopiericidin A (GPA) exhibit hepatotoxicity in renal carcinoma xenograft mice. Proteomics and transcriptomics reveal the hepatotoxicity related with cholesterol disposition since RCC is characterized by cholesterol accumulation. PA/GPA aggravate hepatotoxicity in high-cholesterol diet (HCD)-fed mice while exhibiting no toxicity in chow diet-fed mice. High cholesterol accumulation in liver is liver X receptor (LXR)-mediated cytochrome P450 family 7 subfamily a member 1 (CYP7A1) depression and low-density lipoprotein receptor (LDLR) activation. The farnesoid X nuclear receptor (FXR) is also depressed with a downregulated target gene OSTα. Different from PA directly combined with LXRα as an inhibitor, GPA exists as a prodrug in the liver and exerts toxic effects due to transformation into PA. Surface plasmon resonance (SPR) and docking results of 17 piericidins illustrate that glycosides exert no LXRα binding activity. A longer survival time of GPA-treated mice indicates that further exploration in anti-RCC drug research should focus on reducing glycosides transformed into PA and concentrating in the kidney tumor rather than the liver for lowering the risk of hepatotoxicity.

A novel small molecule approach for the treatment of propionic and methylmalonic acidemias

Propionic Acidemia (PA) and Methylmalonic Acidemia (MMA) are inborn errors of metabolism affecting the catabolism of valine, isoleucine, methionine, threonine and odd-chain fatty acids. These are multi-organ disorders caused by the enzymatic deficiency of propionyl-CoA carboxylase (PCC) or methylmalonyl-CoA mutase (MUT), resulting in the accumulation of propionyl-coenzyme A (P-CoA) and methylmalonyl-CoA (M-CoA in MMA only). Primary metabolites of these CoA esters include 2-methylcitric acid (MCA), propionyl-carnitine (C3), and 3-hydroxypropionic acid, which are detectable in both PA and MMA, and methylmalonic acid, which is detectable in MMA patients only (Chapman et al., 2012). We deployed liver cell-based models that utilized PA and MMA patient-derived primary hepatocytes to validate a small molecule therapy for PA and MMA patients. The small molecule, HST5040, resulted in a dose-dependent reduction in the levels of P-CoA, M-CoA (in MMA) and the disease-relevant biomarkers C3, MCA, and methylmalonic acid (in MMA). A putative working model of how HST5040 reduces the P-CoA and its derived metabolites involves the conversion of HST5040 to HST5040-CoA driving the redistribution of free and conjugated CoA pools, resulting in the differential reduction of the aberrantly high P-CoA and M-CoA. The reduction of P-CoA and M-CoA, either by slowing production (due to increased demands on the free CoA (CoASH) pool) or enhancing clearance (to replenish the CoASH pool), results in a net decrease in the CoA-derived metabolites (C3, MCA and MMA (MMA only)). A Phase 2 study in PA and MMA patients will be initiated in the United States.

Farnesoid X receptor (FXR): Structures and ligands

Farnesoid X receptor (FXR) is a bile acid activated nuclear receptor (BAR) and is mainly expressed in the liver and intestine. Upon ligand binding, FXR regulates key genes involved in the metabolic process of bile acid synthesis, transport and reabsorption and is also involved in the metabolism of carbohydrates and lipids. Because of its important functions, FXR is considered as a promising drug target for the therapy of bile acid-related liver diseases. With the approval of obeticholic acid (OCA) as the first small molecule to target FXR, many other small molecules are being evaluated in clinical trials. This review summarizes the structures of FXR, especially its ligand binding domain, and the development of small molecules (including agonists and antagonists) targeting FXR.

Validation of a multicellular tumor microenvironment system for modeling patient tumor biology and drug response

Lung cancer rates are rising globally and non-small cell lung cancer (NSCLC) has a five year survival rate of only 24%. Unfortunately, the development of drugs to treat cancer is severely hampered by the inefficiency of translating pre-clinical studies into clinical benefit. Thus, we sought to apply a tumor microenvironment system (TMES) to NSCLC. Using microvascular endothelial cells, lung cancer derived fibroblasts, and NSCLC tumor cells in the presence of in vivo tumor-derived hemodynamic flow and transport, we demonstrate that the TMES generates an in-vivo like biological state and predicts drug response to EGFR inhibitors. Transcriptomic and proteomic profiling indicate that the TMES recapitulates the in vivo and patient molecular biological state providing a mechanistic rationale for the predictive nature of the TMES. This work further validates the TMES for modeling patient tumor biology and drug response indicating utility of the TMES as a predictive tool for drug discovery and development and potential for use as a system for patient avatars.

Human hepatic in vitro models reveal distinct anti-NASH potencies of PPAR agonists

Non-alcoholic steatohepatitis (NASH) is a highly prevalent, chronic liver disease characterized by hepatic lipid accumulation, inflammation, and concomitant fibrosis. Up to date, no anti-NASH drugs have been approved. In this study, we reproduced key NASH characteristics in vitro by exposing primary human hepatocytes (PHH), human skin stem cell-derived hepatic cells (hSKP-HPC), HepaRG and HepG2 cell lines, as well as LX-2 cells to multiple factors that play a role in the onset of NASH. The obtained in vitro disease models showed intracellular lipid accumulation, secretion of inflammatory chemokines, induced ATP content, apoptosis, and increased pro-fibrotic gene expression. These cell systems were then used to evaluate the anti-NASH properties of eight peroxisome proliferator-activated receptor (PPAR) agonists (bezafibrate, elafibranor, fenofibrate, lanifibranor, pemafibrate, pioglitazone, rosiglitazone, and saroglitazar). PPAR agonists differently attenuated lipid accumulation, inflammatory chemokine secretion, and pro-fibrotic gene expression.Based on the obtained readouts, a scoring system was developed to grade the anti-NASH potencies. The in vitro scoring system, based on a battery of the most performant models, namely PHH, hSKP-HPC, and LX-2 cultures, showed that elafibranor, followed by saroglitazar and pioglitazone, induced the strongest anti-NASH effects. These data corroborate available clinical data and show the relevance of these in vitro models for the preclinical investigation of anti-NASH compounds.

Modeling Steatohepatitis in Humans with Pluripotent Stem Cell-Derived Organoids

Human organoid systems recapitulate in vivo organ architecture yet fail to capture complex pathologies such as inflammation and fibrosis. Here, using 11 different healthy and diseased pluripotent stem cell lines, we developed a reproducible method to derive multi-cellular human liver organoids composed of hepatocyte-, stellate-, and Kupffer-like cells that exhibit transcriptomic resemblance to in vivo-derived tissues. Under free fatty acid treatment, organoids, but not reaggregated cocultured spheroids, recapitulated key features of steatohepatitis, including steatosis, inflammation, and fibrosis phenotypes in a successive manner. Interestingly, an organoid-level biophysical readout with atomic force microscopy demonstrated that organoid stiffening reflects the fibrosis severity. Furthermore, organoids from patients with genetic dysfunction of lysosomal acid lipase phenocopied severe steatohepatitis, rescued by FXR agonism-mediated reactive oxygen species suppression. The presented key methodology and preliminary results offer a new approach for studying a personalized basis for inflammation and fibrosis in humans, thus facilitating the discovery of effective treatments.

Fibrosis in tissue engineering and regenerative medicine: treat or trigger?

Fibrosis is a life-threatening pathological condition resulting from a dysfunctional tissue repair process. There is no efficient treatment and organ transplantation is in many cases the only therapeutic option. Here we review tissue engineering and regenerative medicine (TERM) approaches to address fibrosis in the cardiovascular system, the kidney, the lung and the liver. These strategies have great potential to achieve repair or replacement of diseased organs by cell- and material-based therapies. However, paradoxically, they might also trigger fibrosis. Cases of TERM interventions with adverse outcome are also included in this review. Furthermore, we emphasize the fact that, although organ engineering is still in its infancy, the advances in the field are leading to biomedically relevant in vitro models with tremendous potential for disease recapitulation and development of therapies. These human tissue models might have increased predictive power for human drug responses thereby reducing the need for animal testing.

Elafibranor restricts lipogenic and inflammatory responses in a human skin stem cell-derived model of NASH

Non-alcoholic steatohepatitis (NASH) is characterized by hepatocellular steatosis with concomitant hepatic inflammation. Despite its pandemic proportions, no anti-NASH drugs have been approved yet. This is partially because drug development is decelerated due to the lack of adequate tools to assess the efficacy of potential new drug candidates. The present study describes the development and application of a new preclinical model for NASH using hepatic cells generated from human skin-derived precursors. Exposure of these cells to lipogenic (insulin, glucose, fatty acids) and pro-inflammatory factors (IL-1β, TNF-α, TGF-β) resulted in a characteristic NASH response, as indicated by intracellular lipid accumulation, modulation of NASH-specific gene expression, increased caspase-3/7 activity and the expression and/or secretion of inflammatory markers, including CCL2, CCL5, CCL7, CCL8, CXCL5, CXCL8, IL1a, IL6 and IL11. The human relevance of the proposed NASH model was verified by transcriptomics analyses that revealed commonly modulated genes and the identification of the same gene classes between the in vitro system and patients suffering from NASH. The application potential of this in vitro model was demonstrated by testing elafibranor, a promising anti-NASH compound currently under clinical phase III trial evaluation. Elafibranor attenuated in vitro key features of NASH, and dramatically lowered lipid load as well as the expression and secretion of inflammatory chemokines, which in vivo are responsible for the recruitment of immune cells. This reduction in inflammatory response was NFκB-mediated. In summary, this human-relevant, in vitro system proved to be a sensitive testing tool for the investigation of novel anti-NASH compounds.

Fibroblast Growth Factor 15/19: From Basic Functions to Therapeutic Perspectives

Discovered 20 years ago, fibroblast growth factor (FGF)19, and its mouse ortholog FGF15, were the first members of a new subfamily of FGFs able to act as hormones. During fetal life, FGF15/19 is involved in organogenesis, affecting the development of the ear, eye, heart, and brain. At adulthood, FGF15/19 is mainly produced by the ileum, acting on the liver to repress hepatic bile acid synthesis and promote postprandial nutrient partitioning. In rodents, pharmacologic doses of FGF19 induce the same antiobesity and antidiabetic actions as FGF21, with these metabolic effects being partly mediated by the brain. However, activation of hepatocyte proliferation by FGF19 has long been a challenge to its therapeutic use. Recently, genetic reengineering of the molecule has resolved this issue. Despite a global overlap in expression pattern and function, murine FGF15 and human FGF19 exhibit several differences in terms of regulation, molecular structure, signaling, and biological properties. As most of the knowledge originates from the use of FGF19 in murine models, differences between mice and humans in the biology of FGF15/19 have to be considered for a successful translation from bench to bedside. This review summarizes the basic knowledge concerning FGF15/19 in mice and humans, with a special focus on regulation of production, morphogenic properties, hepatocyte growth, bile acid homeostasis, as well as actions on glucose, lipid, and energy homeostasis. Moreover, implications and therapeutic perspectives concerning FGF19 in human diseases (including obesity, type 2 diabetes, hepatic steatosis, biliary disorders, and cancer) are also discussed.

A nonalcoholic fatty liver disease model in human induced pluripotent stem cell-derived hepatocytes, created by endoplasmic reticulum stress-induced steatosis

Hepatic steatosis, a reversible state of metabolic dysregulation, can promote the onset of nonalcoholic steatohepatitis (NASH), and its transition is thought to be critical in disease evolution. The association between endoplasmic reticulum (ER) stress response and hepatocyte metabolism disorders prompted us to characterize ER stress-induced hepatic metabolic dysfunction in human induced pluripotent stem cell-derived hepatocytes (hiPSC-Hep), to explore regulatory pathways and validate a phenotypic in vitro model for progression of liver steatosis. We treated hiPSC-Hep with a ratio of unsaturated and saturated fatty acids in the presence of an inducer of ER stress to synergistically promote triglyceride accumulation and dysregulate lipid metabolism. We monitored lipid accumulation by high-content imaging and measured gene regulation by RNA sequencing and reverse transcription quantitative PCR analyses. Our results show that ER stress potentiated intracellular lipid accumulation by 5-fold in hiPSC-Hep in the absence of apoptosis. Transcriptome pathway analysis identified ER stress pathways as the most significantly dysregulated of all pathways affected. Obeticholic acid dose dependently inhibited lipid accumulation and modulated gene expression downstream of the farnesoid X receptor. We were able to identify modulation of hepatic markers and gene pathways known to be involved in steatosis and nonalcoholic fatty liver disease (NAFLD), in support of a hiPSC-Hep disease model that is relevant to clinical data for human NASH. Our results show that the model can serve as a translational discovery platform for the understanding of molecular pathways involved in NAFLD, and can facilitate the identification of novel therapeutic molecules based on high-throughput screening strategies.

Summary: Our study demonstrates expanded use of human induced pluripotent stem cell-derived hepatocytes for molecular studies and drug screening, to evaluate new therapeutics with an antisteatotic mechanism of action for nonalcoholic fatty liver disease.

Human-based systems: Mechanistic NASH modelling just around the corner?

Non-alcoholic steatohepatitis (NASH) is a chronic liver disease characterized by excessive triglyceride accumulation in the liver accompanied by inflammation, cell stress and apoptosis. It is the tipping point to the life-threatening stages of non-alcoholic fatty liver disease (NAFLD). Despite the high prevalence of NASH, up to five percent of the global population, there are currently no approved drugs to treat this disease. Animal models, mostly based on specific diets and genetic modifications, are often employed in anti-NASH drug development. However, due to interspecies differences and artificial pathogenic conditions, they do not represent the human situation accurately and are inadequate for testing the efficacy and safety of potential new drugs. Human-based in vitro models provide a more legitimate representation of the human NASH pathophysiology and can be used to investigate the dysregulation of cellular functions associated with the disease. Also in silico methodologies and pathway-based approaches using human datasets, may contribute to a more accurate representation of NASH, thereby facilitating the quest for new anti-NASH drugs. In this review, we describe the molecular components of NASH and how human-based tools can contribute to unraveling the pathogenesis of this disease and be used in anti-NASH drug development. We also propose a roadmap for the development and application of human-based approaches for future investigation of NASH.

Free-floating adult human brain-derived slice cultures as a model to study the neuronal impact of Alzheimer's disease-associated Aβ oligomers

BACKGROUND

Slice cultures have been prepared from several organs. With respect to the brain, advantages of slice cultures over dissociated cell cultures include maintenance of the cytoarchitecture and neuronal connectivity. Slice cultures from adult human brain have been reported and constitute a promising method to study neurological diseases. Despite this potential, few studies have characterized in detail cell survival and function along time in short-term, free-floating cultures.

NEW METHOD

We used tissue from adult human brain cortex from patients undergoing temporal lobectomy to prepare 200 μm-thick slices. Along the period in culture, we evaluated neuronal survival, histological modifications, and neurotransmitter release. The toxicity of Alzheimer's-associated Aβ oligomers (AβOs) to cultured slices was also analyzed.

RESULTS

Neurons in human brain slices remain viable and neurochemically active for at least four days in vitro, which allowed detection of binding of AβOs. We further found that slices exposed to AβOs presented elevated levels of hyperphosphorylated Tau, a hallmark of Alzheimer's disease.

COMPARISON WITH EXISTING METHOD(S)

Although slice cultures from adult human brain have been previously prepared, this is the first report to analyze cell viability and neuronal activity in short-term free-floating cultures as a function of days in vitro.

CONCLUSIONS

Once surgical tissue is available, the current protocol is easy to perform and produces functional slices from adult human brain. These slice cultures may represent a preferred model for translational studies of neurodegenerative disorders when long term culturing in not required, as in investigations on AβO neurotoxicity.

Translating scientific discovery: the need for preclinical models of nonalcoholic steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in the Western world, affecting about 1/3 of the US general population and remaining as a significant cause of morbidity and mortality. The hallmark of the disease is the excessive accumulation of fat within the liver cells (hepatocytes), which eventually paves the way to cellular stress, injury and apoptosis. NAFLD is strongly associated with components of the metabolic syndrome and is fast emerging as a leading cause of liver transplant in the USA. Based on clinico-pathologic classification, NAFLD may present as isolated lipid collection (steatosis) within the hepatocytes (referred to as non-alcoholic fatty liver; NAFL); or as the more aggressive phenotype (known as non-alcoholic steatohepatitis; NASH). There are currently no regulatory agency- approved medication for NAFLD, despite the enormous work and resources that have gone into the study of this condition. Therefore, there remains a huge unmet need in developing and utilizing pre-clinical models that will recapitulate the disease condition in humans. In line with progress being made in developing appropriate disease models, this review highlights the cutting-edge preclinical in vitro and animal models that try to recapitulate the human disease pathophysiology and/or clinical manifestations.

Non-alcoholic fatty liver disease (NAFLD) models in drug discovery

INTRODUCTION

The progressive disease spectrum of non-alcoholic fatty liver disease (NAFLD), which includes non-alcoholic steatohepatitis (NASH), is a rapidly emerging public health crisis with no approved therapy. The diversity of various therapies under development highlights the lack of consensus around the most effective target, underscoring the need for better translatable preclinical models to study the complex progressive disease and effective therapies. Areas covered: This article reviews published literature of various mouse models of NASH used in preclinical studies, as well as complex organotypic in vitro and ex vivo liver models being developed. It discusses translational challenges associated with both kinds of models, and describes some of the studies that validate their application in NAFLD. Expert opinion: Animal models offer advantages of understanding drug distribution and effects in a whole body context, but are limited by important species differences. Human organotypic in vitro and ex vivo models with physiological relevance and translatability need to be used in a tiered manner with simpler screens. Leveraging newer technologies, like metabolomics, proteomics, and transcriptomics, and the future development of validated disease biomarkers will allow us to fully utilize the value of these models to understand disease and evaluate novel drugs in isolation or combination.