In vitro models for liver toxicity testing

Per- and polyfluoroalkyl substances as potentiators of hepatotoxicity in an exposome framework: Current challenges of environmental toxicology

Chronic liver diseases, including metabolic dysfunction-associated steatosic liver disease (MASLD) and hepatocellular carcinoma (HCC), are on the rise, potentially due to daily exposure to complex mixtures of chemical compounds forming part of the exposome. Understanding the mechanisms involved in hepatotoxicity of these mixtures is essential to identify common molecular targets that may highlight potential interactions at the molecular level. We illustrated this issue with two families of environmental contaminants, per- and polyfluoroalkyl substances (PFAS) and heterocyclic aromatic amines (HAAs), both of which could be involved in the progression of chronic liver diseases, and whose toxicity may be potentiated by interactions at the level of xenobiotic metabolism. In the study of exposome effects on chronic liver disease, New Approach Methodologies (NAMs) including omics analyses and data from various in vitro, in vivo and in silico approaches, are crucial for improving predictivity of toxicological studies in humans while reducing animal experimentation. Additionally, the development of complex in vitro human liver cell models, such as organoids, is essential to avoid interspecies differences that minimize the risk for humans. All together, these approaches will contribute to construct Adverse Outcome Pathways (AOPs) and could be applied not only to PFAS mixtures but also to other chemical families, providing valuable insights into mixture hepatotoxicity prediction in the study of the exposome. A better understanding of toxicological mechanisms will clarify the role of environmental contaminant mixtures in the development of MASLD and HCC, supporting risk assessment for better treatment, monitoring and prevention strategies.

Application of new approach methodologies for nonclinical safety assessment of drug candidates

The development of new approach methodologies (NAMs) and advances with in vitro testing systems have prompted revisions in regulatory guidelines and inspired dedicated in vitro/ex vivo studies for nonclinical safety assessment. This Review by a safety reflection initiative subgroup of the European Federation of Pharmaceutical Industries and Associations (EFPIA)/Preclinical Development Expert Group (PDEG) summarizes the current state and potential application of in vitro studies using human-derived material for safety assessment in drug development. It focuses on case studies from recent projects in which animal models alone proved to be limited or inadequate for safety testing. It further highlights four categories of drug candidates for which alternative in vitro approaches are applicable and discusses progress in using in vitro testing solutions for safety assessment in these categories. Finally, the article highlights new risk assessment strategies, initiatives and consortia promoting the advancement of NAMs. This collective work is meant to encourage the use of NAMs for more human-relevant safety assessment, which should ultimately result in reduced animal testing for drug development.

Protective role of hepatic non-parenchymal cells against drug-induced hepatocyte toxicity using perfluoropolyether-based microfluidic devices

The role of hepatic non-parenchymal cells (NPCs) in drug-induced liver injury has been controversial. Utilizing our previously developed perfluoropolyether-based microfluidic devices-characterized by significantly reduced chemical absorption compared to conventional polydimethylsiloxane (PDMS)-we investigated the interactions between primary hepatocytes (PCs) and NPCs under physiologically relevant conditions. When exposed to coumarin or acetaminophen, PCs underwent severe cytotoxicity and showed glutathione (GSH) depletion. Notably, co-culture with NPCs restored drug-induced cytotoxicity and cellular GSH levels, accompanied by increased interleukin-6 (IL-6) secretion. Given previous reports linking IL-6 to cytochrome P450 expression modulation and glutathione synthesis, these findings suggest that IL-6 might be a critical mediator of protective effects exerted by NPCs. Using these microfluidic devices, we clearly demonstrated the protective roles of NPCs without interference from innate immune systems, offering novel insights into hepatocellular protection mechanisms.

Multi-organ model assessment of neurotoxicity following exposure of liver spheroids to drugs

Accurate prediction of drug toxicity is a major challenge for therapeutic development. The use of animal models for predicting toxicity has been a longstanding practice, but often falls short in accurately predicting human-specific responses. Human in vitro models, such as organoids and spheroids, provide alternative approaches to animal models. In this study, we employed primary human-derived liver spheroids (hLiSps) and human induced pluripotent stem cells (iPSC)-derived brain organoids (hiBOs) to create a combined Liver+Brain model for neurotoxicity assessment, to investigate the potential influence of incorporating a liver preconditioning component on toxic responses in the brain. Comparing the effect of six example drugs that are known to cause adverse clinical neurological effects, we observed that troglitazone (Trgl), tested at clinically relevant doses in the Liver+Brain model, caused a significantly greater reduction in cell viability compared to similar treatments in the Brain-only model. This was further confirmed across multiple donors and various stages of brain organoid development. In contrast, we found that high dose valproic acid treatment increased cell viability in the Liver+Brain model. Transcriptome analysis using RNA-seq revealed that liver-preconditioned Trgl elicited a more pronounced transcriptional response in hiBOs, identifying a 7-fold increase in the number of affected genes and over a 10-fold increase in affected pathways containing gene set components specifically associated with cell division and neurogenesis, which were not observed in the Brain model. Taken together, our data suggest that the addition of hLiSps to hiBOs is critical to accurately assess neurotoxicity using a comprehensive human in vitro model.

Hepatotoxicity evaluation method through multiple-factor analysis using human pluripotent stem cell derived hepatic organoids

Prediction of the potential for drug-induced liver injury (DILI) in the early stages of drug development is important. We developed an organoid-based and functional endpoint method for accurate prediction of DILI. To this end, hepatic organoids (HOs) derived from human pluripotent stem cells (hPSCs) were cocultured with hepatic stellate cells (HSCs) and THP-1 macrophages in Matrigel domes to mimic the cellular and physiological environment of the human liver. To validate our hepatotoxicity prediction model, we selected 12 hepatotoxic reference compounds. As indicators, we used factors related to mechanisms of hepatotoxicity and markers thereof, including factors related to oxidative stress and proinflammatory cytokines. We plotted radar graphs and calculated the relative areas of polygons to analyze the effects of drugs with different degrees of hepatotoxicity. The drugs in the severe DILI group significantly increased the levels of factors related to oxidative stress (ROS, GSSH, and catalase) compared to those in the no and mild DILI groups. The drugs in the severe group significantly increased the levels of inflammation-related factors (IL-1, IL-6, and IL-10). The drugs in the mild and severe groups highly significantly increased the activities of ALT and AST and the level of ALB compared to those in the no DILI group. In summary, the drugs in the severe DILI group had significantly greater effects on the factors analyzed than those in the no DILI group. Therefore, our hepatotoxicity evaluation method is suitable for predicting DILI in the early stages of drug development.

In vitro liver models for toxicological research

Drug-induced liver injury (DILI) presents a major challenge not only in new drug development but also in post-marketing withdrawals and the safety of food, cosmetics, and chemicals. Experimental model organisms such as the rodents have been widely used for preclinical toxicological testing. However, the tension exists associated with the ethical and sustainable use of animals in part because animals do not necessarily inform the human-specific ADME (adsorption, dynamics, metabolism and elimination) profiling. To establish alternative models in humans, in vitro hepatic tissue models have been proposed, ranging from primary hepatocytes, immortal hepatocytes, to the development of new cell resources such as stem cell-derived hepatocytes. Given the evolving number of novel alternative methods, understanding possible combinations of cell sources and culture methods will be crucial to develop the context-of-use assays. This review primarily focuses on 3D liver organoid models for conducting. We will review the relevant cell sources, bioengineering methods, selection of training compounds, and biomarkers towards the rationale design of in vitro toxicology testing.

Development and characterization of a double-crested cormorant hepatic cell line, DCH22, for chemical screening

There are currently no available cell lines for the ecologically relevant colonial waterbird species, the double-crested cormorant (DCCO). DCCOs are high trophic level aquatic birds that are used for routine contaminant monitoring programs in the Laurentian Great Lakes and marine coasts of Canada. Developing a DCCO cell line for in vitro toxicological screening will ideally provide improved understanding of the effects of environmental chemicals given the large differences in sensitivity between laboratory and wild avian species. In this study, an immortalized DCCO hepatic cell line, DCH22, was established from the liver of a day 22 female embryo as a potential alternative to primary DCCO embryonic hepatocytes (DCEH) for chemical screening. DCH22 cells were cultured for over a year and have hepatocyte-like morphology. Exposure to 3,3',4,4',5-pentachlorobiphenyl (PCB-126), benzo-a-pyrene, ß-napthoflavone and phenacetin induced CYP1A activity and mRNA expression in DCH22 3D spheroids. Induction of CYP3A activity and mRNA expression was observed following exposure to hexabromocyclododecane (HBCD), tris(1,3-dichloroisopropyl)phosphate, carbamazepine, and metyrapone. The phase II metabolism gene, UGT1A1, was upregulated following HBCD exposure and DCH22 spheroids expressed vitellogenin protein after exposure to 17α-ethinylestradiol. Based on these data, the novel DCH22 cell line, cultured as 3D spheroids, has potential use as an alternative to DCEH for chemical screening and will permit the evaluation of avian species differences in sensitivity from an in vitro screening perspective.

Liver organoids: Current advances and future applications for hepatology

The creation of self-organizing liver organoids represents a significant, although modest, step toward addressing the ongoing organ shortage crisis in allogeneic liver transplantation. However, researchers have recognized that achieving a fully functional whole liver remains a distant goal, and the original ambition of organoid-based liver generation has been temporarily put on hold. Instead, liver organoids have revolutionized the field of hepatology, extending their influence into various domains of precision and molecular medicine. These 3D cultures, capable of replicating key features of human liver function and pathology, have opened new avenues for human-relevant disease modeling, CRISPR gene editing, and high-throughput drug screening that animal models cannot accomplish. Moreover, advancements in creating more complex systems have led to the development of multicellular assembloids, dynamic organoid-on-chip systems, and 3D bioprinting technologies. These innovations enable detailed modeling of liver microenvironments and complex tissue interactions. Progress in regenerative medicine and transplantation applications continues to evolve and strives to overcome the obstacles of biocompatibility and tumorigenecity. In this review, we examine the current state of liver organoid research by offering insights into where the field currently stands, and the pivotal developments that are shaping its future.

Metabolic Biomarkers of Liver Failure in Cell Models and Patient Sera: Toward Liver Damage Evaluation In Vitro

Recent research has concentrated on the development of suitable in vitro cell models for the early identification of hepatotoxicity during drug development in order to reduce the number of animal models and to obtain a better predictability for hepatotoxic reactions in humans. The aim of the presented study was to identify translational biomarkers for acute liver injury in human patients that can serve as biomarkers for hepatocellular injury in vivo and in vitro in simple cell models. Therefore, 188 different metabolites from patients with acute-on-chronic liver failure before and after liver transplantation were analyzed with mass spectrometry. The identified potential metabolic biomarker set, including acylcarnitines, phosphatidylcholines and sphingomyelins, was used to screen primary and permanent hepatocyte culture models for their ability to model hepatotoxic responses caused by different drugs with known and unknown hepatotoxic potential. The results obtained suggest that simple in vitro cell models have the capability to display metabolic responses in biomarkers for liver cell damage in course of the treatment with different drugs and therefore can serve as a basis for in vitro models for metabolic analysis in drug toxicity testing. The identified metabolites should further be evaluated for their potential to serve as a metabolic biomarker set indicating hepatocellular injury in vitro as well as in vivo.

A proposed in vitro cytotoxicity test battery to detect and predict hepatotoxicity via multiple mechanisms and pathways: a minireview

The 21st-century toxicity testing program recommends the use of cytotoxicity data from human cells in culture for rapid in vitro screening focusing on biological pathways of potential toxicants to predict in vivo toxicity. Liver is the major organ for both endogenous and exogenous chemical metabolism of xenobiotics. Therefore, this review was undertaken to evaluate side by side five different currently used commercial cytotoxicity assay kits for purpose of rapid predictive screening of potential hepatotoxicants. The test compounds for this review were selected from the NIH LiverTox and FDA Liver Toxicity Knowledge Base (LTKB) databases. Human liver HepG2, HepaRG, and rat liver Clone 9 cell cultures were used as the in vitro liver models. Five commercial assay kits representing different biomarkers or pathways were selected for this review. These kits are Vita-Orange Cell Viability Assay Kit (Sigma-Aldrich), CellTiter-Glo Cell Viability Assay Kit (Promega), CytoTox-ONE Homogeneous Membrane Integrity Assay Kit (Promega), DNA Quantitation Fluorescence Assay Kit (Sigma-Aldrich), and Neutral Red Based In Vitro Toxicology Assay Kit (Sigma-Aldrich). This review found that these kits can all be used for rapid predictive cytotoxicity screening of potential hepatotoxicants in human liver HepG2 and rat liver Clone 9 cells in culture as in vitro liver models without compromising quality and accuracy of endpoint measurements as well as the length of toxicity screening time. Unraveling the structure-activity relationship of potential hepatotoxins would help to classify their hepatotoxic effects. Therefore, in addition to the current regulatory hepatotoxicity testing strategies, development and regulatory approval of hepatotoxins need to be discussed in order to identify potential gaps in the safety assessment. The overall results of our study support the hypothesis that a battery of rapid, simple, and reliable assays is an excellent tool for predicting in vivo effects of suspected liver toxins. The human liver HepaRG cells do not appear to be an ideal in vitro liver model for this purpose.

Time-course characterization of whole-transcriptome dynamics of HepG2/C3A spheroids and its toxicological implications

Physiologically relevant in vitro models are a priority in predictive toxicology to replace and/or reduce animal experiments. The compromised toxicant metabolism of many immortalized human liver cell lines grown as monolayers as compared to in vivo metabolism limits their physiological relevance. However, recent efforts to culture liver cells in a 3D environment, such as spheroids, to better mimic the in vivo conditions, may enhance the toxicant metabolism of human liver cell lines. In this study, we characterized the dynamic changes in the transcriptome of HepG2/C3A hepatocarcinoma cell spheroids maintained in a clinostat system (CelVivo) to gain insight into the metabolic capacity of this model as a function of spheroid size and culture time. We assessed morphological changes (size, necrotic core), cell health, and proliferation rate from initial spheroid seeding to 35 days of continuous culture in conjunction with a time-course (0, 3, 7, 10, 14, 21, 28 days) of the transcriptome (TempO-Seq, BioSpyder). The phenotypic characteristics of HepG2/C3A growing in spheroids were comparable to monolayer growth until ∼Day 12 (Day 10-14) when a significant decrease in cell doubling rate was noted which was concurrent with down-regulation of cell proliferation and cell cycle pathways over this time period. Principal component analysis of the transcriptome data suggests that the Day 3, 7, and 10 spheroids are pronouncedly different from the Day 14, 21, and 28 spheroids in support of a biological transition time point during the long-term 3D spheroid cultures. The expression of genes encoding cellular components involved in toxicant metabolism and transport rapidly increased during the early time points of spheroids to peak at Day 7 or Day 10 as compared to monolayer cultures with a gradual decrease in expression with further culture, suggesting the most metabolically responsive time window for exposure studies. Overall, we provide baseline information on the cellular and molecular characterization, with a particular focus on toxicant metabolic capacity dynamics and cell growth, of HepG2/C3A 3D spheroid cultures over time.

Protocol to create phenotypic primary human hepatocyte cultures using the RASTRUM 3D cell model platform

To improve human hepatotoxicity prediction, in vitro liver cell models replicating hepatocyte function, drug metabolism, and toxicity are required. Here, we present a protocol for creating 3D primary human hepatocyte (PHH) cell models using the RASTRUM Platform. We describe the process for PHH model generation; procedures for characterizing the PHH model, including viability, albumin production, and CYP450 inducibility; and drug treatment using acetaminophen and troglitazone. This protocol has applications in upscaling phenotypic hepatotoxicity applications.

Human Multi-Lineage Liver Organoid Model Reveals Impairment of CYP3A4 Expression upon Repeated Exposure to Graphene Oxide

Three-dimensional hepatic cell cultures can provide an important advancement in the toxicity assessment of nanomaterials with respect to 2D models. Here, we describe liver organoids (LOs) obtained by assembling multiple cell lineages in a fixed ratio 1:1:0.2. These are upcyte® human hepatocytes, UHHs, upcyte® liver sinusoidal endothelial cells, LSECs, and human bone marrow-derived mesenchymal stromal cells, hbmMSCs. The structural and functional analyses indicated that LOs reached size stability upon ca. 10 days of cultivation (organoid maturation), showing a surface area of approximately 10 mm2 and the hepatic cellular lineages, UHHs and LSECs, arranged to form both primitive biliary networks and sinusoid structures, alike in vivo. LOs did not show signs of cellular apoptosis, senescence, or alteration of hepatocellular functions (e.g., dis-regulation of CYP3A4 or aberrant production of Albumin) for the entire culture period (19 days since organoid maturation). After that, LOs were repeatedly exposed for 19 days to a single or repeated dose of graphene oxide (GO: 2-40 µg/mL). We observed that the treatment did not induce any macroscopic signs of tissue damage, apoptosis activation, and alteration of cell viability. However, in the repeated dose regimen, we observed a down-regulation of CYP3A4 gene expression. Notably, these findings are in line with recent in vivo data, which report a similar impact on CYP3A4 when mice were repeatedly exposed to GO. Taken together, these findings warn of the potential detrimental effects of GO in real-life exposure (e.g., occupational scenario), where its progressive accumulation is likely expected. More in general, this study highlights that LOs formed by many cell lineages can enable repeated exposure regimens (suitable to mimic accumulation); thus, they can be suitably considered alternative or complementary in vitro systems to animal models.

Investigation of parenteral nutrition-induced hepatotoxicity using human liver spheroid co-cultures

Parenteral nutrition (PN) is typically administered to individuals with gastrointestinal dysfunction, a contraindication for enteral feeding, and a need for nutritional therapy. When PN is the only energy source in patients, it is defined as total parenteral nutrition (TPN). TPN is a life-saving approach for different patient populations, both in infants and adults. However, despite numerous benefits, TPN can cause adverse effects, including metabolic disorders and liver injury. TPN-associated liver injury, known as intestinal failure-associated liver disease (IFALD), represents a significant problem affecting up to 90% of individuals receiving TPN. IFALD pathogenesis is complex, depending on the TPN components as well as on the patient's medical conditions. Despite numerous animal studies and clinical observations, the molecular mechanisms driving IFALD remain largely unknown. The present study was set up to elucidate the mechanisms underlying IFALD. For this purpose, human liver spheroid co-cultures were treated with a TPN mixture, followed by RNA sequencing analysis. Subsequently, following exposure to TPN and its single nutritional components, several key events of liver injury, including mitochondrial dysfunction, endoplasmic reticulum stress, oxidative stress, apoptosis, and lipid accumulation (steatosis), were studied using various techniques. It was found that prolonged exposure to TPN substantially changes the transcriptome profile of liver spheroids and affects multiple metabolic and signaling pathways contributing to liver injury. Moreover, TPN and its main components, especially lipid emulsion, induce changes in all key events measured and trigger steatosis.

α-amanitin induce inflammatory response by activating ROS/NF-κB-NLRP3 signaling pathway in human hepatoma HepG2 cells

α-amanitin (AMA) is a hepatotoxic mushroom toxin responsible for over 90% of mushroom poisoning fatalities worldwide, seriously endangering human life and health. Few evidences have indicated that AMA leads to inflammatory responses and inflammatory infiltration in vitro and in vivo. However, the molecular mechanism remains unknown. In this study, human hepatocellular carcinomas cells (HepG2) were exposed to AMA at various concentrations for short period of times. Results revealed that AMA increased ROS production and elevated the releases of malondialdehyde (MDA) and lactate dehydrogenase (LDH), resulting in oxidative damage in HepG2 cells. Also, AMA exposure significantly increased the secreted levels of inflammatory cytokines and activated the NLRP3 inflammasome. The inflammatory responses were reversed by NLRP3 inhibitor MCC950 and NF-κB inhibitor Bay11-7082. Additionally, N-acetylcysteine (NAC) blocked the upregulation of the NF-κB/NLRP3 signaling pathway and remarkably alleviated the inflammatory response. These results demonstrated that AMA could induce inflammation through activating the NLRP3 inflammasome triggered by ROS/NF-κB signaling pathway. Our research provides new insights into the molecular mechanism of AMA-induced inflammation damage and may contribute to establish new prevention strategies for AMA hepatotoxicity.

Assessing Receptor Activation in 2D and 3D Cultured Hepatocytes: Responses to a Single Compound and a Complex Mixture

Responding to global standards and legislative updates in Canada, including Bill S-5 (2023), toxicity testing is shifting towards more ethical, in vitro methods. Traditional two-dimensional (2D) monolayer cell cultures, limited in replicating the complex in vivo environment, have prompted the development of more relevant three-dimensional (3D) spheroidal hepatocyte cultures. This study introduces the first 3D spheroid model for McA-RH7777 cells, assessing xenobiotic receptor activation, cellular signaling, and toxicity against dexamethasone and naphthenic acid (NA)-fraction components; NAFCs. Our findings reveal that 3D McA-RH7777 spheroids demonstrate enhanced sensitivity and more uniform dose-response patterns in gene expression related to xenobiotic metabolism (AhR and PPAR) for both single compounds and complex mixtures. Specifically, 3D cultures showed significant gene expression changes upon dexamethasone exposure and exhibited varying degrees of sensitivity and resistance to the apoptotic effects induced by NAFCs, in comparison to 2D cultures. The optimization of 3D culture conditions enhances the model's physiological relevance and enables the identification of genomic signatures under varied exposures. This study highlights the potential of 3D spheroid cultures in providing a more accurate representation of the liver's microenvironment and advancing our understanding of cellular mechanisms in toxicity testing.

Complexin vitromodels positioned for impact to drug testing in pharma: a review

Recent years have seen the creation and popularization of various complexin vitromodels (CIVMs), such as organoids and organs-on-chip, as a technology with the potential to reduce animal usage in pharma while also enhancing our ability to create safe and efficacious drugs for patients. Public awareness of CIVMs has increased, in part, due to the recent passage of the FDA Modernization Act 2.0. This visibility is expected to spur deeper investment in and adoption of such models. Thus, end-users and model developers alike require a framework to both understand the readiness of current models to enter the drug development process, and to assess upcoming models for the same. This review presents such a framework for model selection based on comparative -omics data (which we term model-omics), and metrics for qualification of specific test assays that a model may support that we term context-of-use (COU) assays. We surveyed existing healthy tissue models and assays for ten drug development-critical organs of the body, and provide evaluations of readiness and suggestions for improving model-omics and COU assays for each. In whole, this review comes from a pharma perspective, and seeks to provide an evaluation of where CIVMs are poised for maximum impact in the drug development process, and a roadmap for realizing that potential.

Improved Detection of Drug-Induced Liver Injury by Integrating Predicted In Vivo and In Vitro Data

Drug-induced liver injury (DILI) has been a significant challenge in drug discovery, often leading to clinical trial failures and necessitating drug withdrawals. Over the last decade, the existing suite of in vitro proxy-DILI assays has generally improved at identifying compounds with hepatotoxicity. However, there is considerable interest in enhancing the in silico prediction of DILI because it allows for evaluating large sets of compounds more quickly and cost-effectively, particularly in the early stages of projects. In this study, we aim to study ML models for DILI prediction that first predict nine proxy-DILI labels and then use them as features in addition to chemical structural features to predict DILI. The features include in vitro (e.g., mitochondrial toxicity, bile salt export pump inhibition) data, in vivo (e.g., preclinical rat hepatotoxicity studies) data, pharmacokinetic parameters of maximum concentration, structural fingerprints, and physicochemical parameters. We trained DILI-prediction models on 888 compounds from the DILI data set (composed of DILIst and DILIrank) and tested them on a held-out external test set of 223 compounds from the DILI data set. The best model, DILIPredictor, attained an AUC-PR of 0.79. This model enabled the detection of the top 25 toxic compounds (2.68 LR+, positive likelihood ratio) compared to models using only structural features (1.65 LR+ score). Using feature interpretation from DILIPredictor, we identified the chemical substructures causing DILI and differentiated cases of DILI caused by compounds in animals but not in humans. For example, DILIPredictor correctly recognized 2-butoxyethanol as nontoxic in humans despite its hepatotoxicity in mice models. Overall, the DILIPredictor model improves the detection of compounds causing DILI with an improved differentiation between animal and human sensitivity and the potential for mechanism evaluation. DILIPredictor required only chemical structures as input for prediction and is publicly available at https://broad.io/DILIPredictor for use via web interface and with all code available for download.

Improved Detection of Drug-Induced Liver Injury by Integrating Predicted in vivo and in vitro Data

Drug-induced liver injury (DILI) has been significant challenge in drug discovery, often leading to clinical trial failures and necessitating drug withdrawals. The existing suite of in vitro proxy-DILI assays is generally effective at identifying compounds with hepatotoxicity. However, there is considerable interest in enhancing in silico prediction of DILI because it allows for the evaluation of large sets of compounds more quickly and cost-effectively, particularly in the early stages of projects. In this study, we aim to study ML models for DILI prediction that first predicts nine proxy-DILI labels and then uses them as features in addition to chemical structural features to predict DILI. The features include in vitro (e.g., mitochondrial toxicity, bile salt export pump inhibition) data, in vivo (e.g., preclinical rat hepatotoxicity studies) data, pharmacokinetic parameters of maximum concentration, structural fingerprints, and physicochemical parameters. We trained DILI-prediction models on 888 compounds from the DILIst dataset and tested on a held-out external test set of 223 compounds from DILIst dataset. The best model, DILIPredictor, attained an AUC-ROC of 0.79. This model enabled the detection of top 25 toxic compounds compared to models using only structural features (2.68 LR+ score). Using feature interpretation from DILIPredictor, we were able to identify the chemical substructures causing DILI as well as differentiate cases DILI is caused by compounds in animals but not in humans. For example, DILIPredictor correctly recognized 2-butoxyethanol as non-toxic in humans despite its hepatotoxicity in mice models. Overall, the DILIPredictor model improves the detection of compounds causing DILI with an improved differentiation between animal and human sensitivity as well as the potential for mechanism evaluation. DILIPredictor is publicly available at https://broad.io/DILIPredictor for use via web interface and with all code available for download and local implementation via https://pypi.org/project/dilipred/.

Fabrication of a decellularized liver matrix-based hepatic patch for the repair of CCl4-induced liver injury

This article primarily introduces a new treatment for liver fibrosis/cirrhosis. We developed a hepatic patch by combining decellularized liver matrix (DLM) with the hepatocyte growth factor (HGF)/heparin-complex and evaluated its restorative efficacy. In vitro prophylactic results, the HGF/heparin-DLM patches effectively mitigated CCl4-induced hepatocyte toxicity and restored the cytotoxicity levels to the baseline levels by day 5. Furthermore, these patches restored albumin synthesis of injured hepatocytes to more than 70% of the normal levels within 5 days. In vitro therapeutic results, the urea synthesis of the injured hepatocytes reached 91% of the normal levels after 10 days of culture, indicating successful restoration of hepatic function by the HGF/heparin-DLM patches in both prophylactic and therapeutic models. In vivo results, HGF/heparin-DLM patches attached to the liver and gut exhibited a significant decrease in collagen content (4.44 times and 2.77 times, respectively) and an increase in glycogen content (1.19 times and 1.12 times, respectively) compared to the fibrosis group after 1 week, separately. In summary, liver function was restored and inflammation was inhibited through the combined effects of DLM and the HGF/heparin-complex in fibrotic liver. The newly designed hepatic patch holds promise for both in vitro and in vivo regeneration therapy and preventive health care for liver tissue engineering.

Cryopreservation and Rapid Recovery of Differentiated Intestinal Epithelial Barrier Cells at Complex Transwell Interfaces Is Enabled by Chemically Induced Ice Nucleation

Cell-based models, such as organ-on-chips, can replace and inform in vivo (animal) studies for drug discovery, toxicology, and biomedical science, but most cannot be banked "ready to use" as they do not survive conventional cryopreservation with DMSO alone. Here, we demonstrate how macromolecular ice nucleators enable the successful cryopreservation of epithelial intestinal models supported upon the interface of transwells, allowing recovery of function in just 7 days post-thaw directly from the freezer, compared to 21 days from conventional suspension cryopreservation. Caco-2 cells and Caco-2/HT29-MTX cocultures are cryopreserved on transwell inserts, with chemically induced ice nucleation at warmer temperatures resulting in increased cell viability but crucially retaining the complex cellular adhesion on the transwell insert interfaces, which other cryoprotectants do not. Trans-epithelial electrical resistance measurements, confocal microscopy, histology, and whole-cell proteomics demonstrated the rapid recovery of differentiated cell function, including the formation of tight junctions. Lucifer yellow permeability assays confirmed that the barrier functions of the cells were intact. This work will help solve the long-standing problem of transwell tissue barrier model storage, facilitating access to advanced predictive cellular models. This is underpinned by precise control of the nucleation temperature, addressing a crucial biophysical mode of damage.

Comparison of Glioblastoma Cell Culture Platforms Based on Transcriptional Similarity with Paired Tissue

No standardized in vitro cell culture models for glioblastoma (GBM) have yet been established, excluding the traditional two-dimensional culture. GBM tumorspheres (TSs) have been highlighted as a good model platform for testing drug effects and characterizing specific features of GBM, but a detailed evaluation of their suitability and comparative performance is lacking. Here, we isolated GBM TSs and extracellular matrices (ECM) from tissues obtained from newly diagnosed IDH1 wild-type GBM patients and cultured GBM TSs on five different culture platforms: (1) ordinary TS culture liquid media (LM), (2) collagen-based three-dimensional (3D) matrix, (3) patient typical ECM-based 3D matrix, (4) patient tumor ECM-based 3D matrix, and (5) mouse brain. For evaluation, we obtained transcriptome data from all cultured GBM TSs using microarrays. The LM platform exhibited the most similar transcriptional program to paired tissues based on GBM genes, stemness- and invasiveness-related genes, transcription factor activity, and canonical signaling pathways. GBM TSs can be cultured via an easy-to-handle and cost- and time-efficient LM platform while preserving the transcriptional program of the originating tissues without supplementing the ECM or embedding it into the mouse brain. In addition to applications in basic cancer research, GBM TSs cultured in LM may also serve as patient avatars in drug screening and pre-clinical evaluation of targeted therapy and as standardized and clinically relevant models for precision medicine.

Embryonic growth and effect of embryonic age on quantitative and functional characteristics of duck primary hepatocytes

Primary hepatocytes (PH) have been widely used in metabolic and disease-resistance mechanism research. However, hepatocyte isolation (HI) remains challenging in ducks. This study aimed to explore embryonic growth and the effect of embryonic age (EA) on the quantitative and functional characteristics of PH in ducks. For embryonic growth, the size and weight of the embryo and liver were determined from 6 to 28 EA (E6-E28, similar below). As EA increased, the corresponding size and weight grew significantly. Specifically, embryonic length varied from 12.5 mm to 133.0 mm, and liver width varied from 2.0 mm to 26.2 mm. Embryonic weight ranged from 0.259 g to 53.58 g, and liver weight ranged from 0.007 g to 1.765 g. Liver index initially decreased and then increased with a ratio ranging from 1.06 to 3.29%. For quantitative and functional characteristics, they were determined from E6 to E22, as there were no obvious liver features before E6 and few cells obtained after E22. The number of cells isolated in liver increased from E6 to E16 and then sharply decreased from E16 to E22. The viability remained relatively stable from E6 to E10 and then decreased from E12 to E22. The comprehensive intensity of hepatic glycogen was stronger at E8 and E14. Albumin expression increased markedly from E6 to E18 by qPCR, and the overall albumin expression was stronger at E8 and E14 by immunofluorescence assay. Hepatocyte purity exceeded 90% except for E20 and E22. During culture, cell clusters appeared after 24-h culture, which were identified as nonhepatocytes. The growth curve showed an initial increase in cell quantity followed by a decrease, another increase, and then remaining stable. In conclusion, EA had a significant effect on the quantitative and functional characteristics of PH, and the suitable EA for HI were E8 and E14. Considering better operability and quantity, E14 was the optimal EA, laying a solid foundation for further hepatocyte purification, nutrient metabolism, and disease-resistance mechanism explorations in ducks.

Risk-based prioritization of PFAS using phenotypic and transcriptomic data from human induced pluripotent stem cell-derived hepatocytes and cardiomyocytes

Per- and polyfluoroalkyl substances (PFAS) are chemicals with important applications; they are persistent in the environment and may pose human health hazards. Regulatory agencies are con­sidering restrictions and bans of PFAS; however, little data exists for informed decisions. Several prioritization strategies were proposed for evaluation of potential hazards of PFAS. Structure-based grouping could expedite the selection of PFAS for testing; still, the hypothesis that structure-effect relationships exist for PFAS requires confirmation. We tested 26 structurally diverse PFAS from 8 groups using human induced pluripotent stem cell-derived hepatocytes and cardiomyocytes, and tested concentration-response effects on cell function and gene expression. Few phenotypic effects were observed in hepatocytes, but negative chronotropy was observed in cardiomyocytes for 8 PFAS. Substance- and cell type-dependent transcriptomic changes were more prominent but lacked substantial group-specific effects. In hepatocytes, we found upregulation of stress-related and extracellular matrix organization pathways, and down-regulation of fat metabolism. In car­diomyocytes, contractility-related pathways were most affected. We derived phenotypic and transcriptomic points of departure and compared them to predicted PFAS exposures. Conservative estimates for bioactivity and exposure were used to derive a bioactivity-to-exposure ratio (BER) for each PFAS; 23 of 26 PFAS had BER > 1. Overall, these data suggest that structure-based PFAS grouping may not be sufficient to predict their biological effects. Testing of individual PFAS may be needed for scientifically-supported decision-making. Our proposed strategy of using two human cell types and considering phenotypic and transcriptomic effects, combined with dose-response analysis and calculation of BER, may be used for PFAS prioritization.

A Review of CYP-Mediated Drug Interactions: Mechanisms and In Vitro Drug-Drug Interaction Assessment

Drug metabolism is a major determinant of drug concentrations in the body. Drug-drug interactions (DDIs) caused by the co-administration of multiple drugs can lead to alteration in the exposure of the victim drug, raising safety or effectiveness concerns. Assessment of the DDI potential starts with in vitro experiments to determine kinetic parameters and identify risks associated with the use of comedication that can inform future clinical studies. The diverse range of experimental models and techniques has significantly contributed to the examination of potential DDIs. Cytochrome P450 (CYP) enzymes are responsible for the biotransformation of many drugs on the market, making them frequently implicated in drug metabolism and DDIs. Consequently, there has been a growing focus on the assessment of DDI risk for CYPs. This review article provides mechanistic insights underlying CYP inhibition/induction and an overview of the in vitro assessment of CYP-mediated DDIs.

Coculture model of a liver sinusoidal endothelial cell barrier and HepG2/C3a spheroids-on-chip in an advanced fluidic platform

The liver is one of the main organs involved in the metabolism of xenobiotics and a key organ in toxicity studies. Prior to accessing the hepatocytes, xenobiotics pass through the hepatic sinusoid formed by liver sinusoidal endothelial cells (LSECs). The LSECs barrier regulates the kinetics and concentrations of the xenobiotics before their metabolic processing by the hepatocytes. To mimic this physiological situation, we developed an in vitro model reproducing an LSECs barrier in coculture with a hepatocyte biochip, using a fluidic platform. This technology made dynamic coculture and tissue crosstalk possible. SK-HEP-1 and HepG2/C3a cells were used as LSECs and as hepatocyte models, respectively. We confirmed the LSECs phenotype by measuring PECAM-1 and stabilin-2 expression levels and the barrier's permeability/transport properties with various molecules. The tightness of the SK-HEP-1 barrier was enhanced in the dynamic coculture. The morphology, albumin secretion, and gene expression levels of markers of HepG2/C3a were not modified by coculture with the LSECs barrier. Using acetaminophen, a well-known hepatotoxic drug, to study tissue crosstalk, there was a reduction in the expression levels of the LSECs markers stabilin-2 and PECAM-1, and a modification of those of CLEC4M and KDR. No HepG2/C3a toxicity was observed. The metabolisation of acetaminophen by HepG2/C3a monocultures and cocultures was confirmed. Although primary cells are required to propose a fully relevant model, the present approach highlights the potential of our system for investigating xenobiotic metabolism and toxicity.

Mevinphos induces developmental defects via inflammation, apoptosis, and altered MAPK and Akt signaling pathways in zebrafish

Mevinphos, an organophosphate insecticide, is widely used to control pests and enhance crop yield. Because of its high solubility, it can easily flow into water and threaten the aquatic environment, and it is known to be hazardous to non-target organisms. However, little is known about its developmental toxicity and the underlying toxic mechanisms. In this study, we utilized zebrafish, which is frequently used for toxicological research to estimate the toxicity in other aquatic organisms or vertebrates including humans, to elucidate the developmental defects induced by mevinphos. Here, we observed that mevinphos induced various phenotypical abnormalities, such as diminished eyes and head sizes, shortened body length, loss of swim bladder, and increased pericardiac edema. Also, exposure to mevinphos triggered inflammation, apoptosis, and DNA fragmentation in zebrafish larvae. In addition, MAPK and Akt signaling pathways, which control apoptosis, inflammation, and proper development of various organs, were also altered by the treatment of mevinphos. Furthermore, these factors induced various organ defects which were confirmed by various transgenic models. We identified neuronal toxicity through transgenic olig2:dsRed zebrafish, cardiovascular toxicity through transgenic fli1:eGFP zebrafish, and hepatotoxicity and pancreatic toxicity through transgenic lfabp:dsRed;elastase:GFP zebrafish. Overall, our results elucidated the developmental toxicities of mevinphos in zebrafish and provided the parameters for the assessment of toxicities in aquatic environments.

Isolation and characterization of the morphology, size and particle number of rainbow trout (Oncorhynchus mykiss) and zebrafish (Danio rerio) cell line derived large and small extracellular vesicles

Extracellular vesicles (EVs) are 50-1,000 nm lipid bilayer-bound vesicles, released into the extracellular environment by various cell types for intercellular communication purposes. The quantitative and qualitative characteristics of EVs can be affected by stress and pathological conditions. The majority of extracellular vesicle (EV) studies have been performed on mammalian cell lines or bodily fluids. EVs have been previously described from bodily fluids like plasma, serum or mucus in different fish species, however the available knowledge of fish cell line derived EVs is limited and in the vast majority of studies, the overall focus is on small EVs (< 200 nm). We isolated large and small extracellular vesicles from zebrafish (Danio rerio) liver (ZFL), rainbow trout (Oncorhynchus mykiss) liver (RTL-W1), gill (RTgill-W1) and intestinal epithelial (RTgutGC) cell lines using stepwise centrifugation and characterized the size and morphology of EVs. Here we demonstrated that large and small extracellular vesicles can be successfully isolated using stepwise centrifugation from the serum-free medium of the selected piscine cell lines after a 24-h incubation period. The size distribution of large and small EVs isolated from the piscine cell lines suggest that large and small EV groups show high diversity in size ranges, containing heterogenous subpopulations in sizes, and the results highly depend on the applied method and whether filtration steps were included following the isolation. The spherical morphology of EVs was verified by transmission electron microscopy.

Profiling the Physiological Roles in Fish Primary Cell Culture

Fish primary cell culture has emerged as a valuable tool for investigating the physiological roles and responses of various cell types found in fish species. This review aims to provide an overview of the advancements and applications of fish primary cell culture techniques, focusing on the profiling of physiological roles exhibited by fish cells in vitro. Fish primary cell culture involves the isolation and cultivation of cells directly derived from fish tissues, maintaining their functional characteristics and enabling researchers to study their behavior and responses under controlled conditions. Over the years, significant progress has been made in optimizing the culture conditions, establishing standardized protocols, and improving the characterization techniques for fish primary cell cultures. The review highlights the diverse cell types that have been successfully cultured from different fish species, including gonad cells, pituitary cells, muscle cells, hepatocytes, kidney and immune cells, adipocyte cells and myeloid cells, brain cells, primary fin cells, gill cells, and other cells. Each cell type exhibits distinct physiological functions, contributing to vital processes such as metabolism, tissue regeneration, immune response, and toxin metabolism. Furthermore, this paper explores the pivotal role of fish primary cell culture in elucidating the mechanisms underlying various physiological processes. Researchers have utilized fish primary cell cultures to study the effects of environmental factors, toxins, pathogens, and pharmaceutical compounds on cellular functions, providing valuable insights into fish health, disease pathogenesis, and drug development. The paper also discusses the application of fish primary cell cultures in aquaculture research, particularly in investigating fish growth, nutrition, reproduction, and stress responses. By mimicking the in vivo conditions in vitro, primary cell culture has proven instrumental in identifying key factors influencing fish health and performance, thereby contributing to the development of sustainable aquaculture practices.

Study Models of Drug-Drug Interactions Involving P-Glycoprotein: The Potential Benefit of P-Glycoprotein Modulation at the Kidney and Intestinal Levels

P-glycoprotein (P-gp) is a crucial membrane transporter situated on the cell's apical surface, being responsible for eliminating xenobiotics and endobiotics. P-gp modulators are compounds that can directly or indirectly affect this protein, leading to changes in its expression and function. These modulators can act as inhibitors, inducers, or activators, potentially causing drug-drug interactions (DDIs). This comprehensive review explores diverse models and techniques used to assess drug-induced P-gp modulation. We cover several approaches, including in silico, in vitro, ex vivo, and in vivo methods, with their respective strengths and limitations. Additionally, we explore the therapeutic implications of DDIs involving P-gp, with a special focus on the renal and intestinal elimination of P-gp substrates. This involves enhancing the removal of toxic substances from proximal tubular epithelial cells into the urine or increasing the transport of compounds from enterocytes into the intestinal lumen, thereby facilitating their excretion in the feces. A better understanding of these interactions, and of the distinct techniques applied for their study, will be of utmost importance for optimizing drug therapy, consequently minimizing drug-induced adverse and toxic effects.

Metabolism of natural and synthetic bioactive compounds in Cunninghamella fungi and their applications in drug discovery

Investigation of xenobiotic metabolism is a key step for drug discovery. Since the in vivo investigations may be associated with harmful effects attributed to production of toxic metabolites, it is deemed necessary to predict their structure especially at the preliminary clinical studies. Furthermore, the application of microorganisms that are capable of metabolizing drugs mimic human metabolism and consequently may predict possible metabolites. The genus Cunninghamella has been proven to be a potential candidate, which mimics xenobiotic metabolism occurring inside the human body, including phase I and II metabolic reactions. Moreover, biotransformation with Cunninghamella showed chemical diversity, where a lot of products were detected in relation to the initial substrates after being modified by oxidation, hydroxylation, and conjugation reactions. Some of these products are more bioactive than the parent compounds. The current review presents a comprehensive literature overview regarding the Cunninghamella organisms as biocatalysts, which simulate mammalian metabolism of natural secondary and synthetic compounds.

Exploring the Boundaries for In Vitro-In Vivo Extrapolation: Use of Isolated Rat Hepatocytes in Co-culture and Impact of Albumin Binding Properties in the Prediction of Clearance of Various Drug Types

Prediction of hepatic clearance of drugs (via uptake or metabolism) from in vitro systems continues to be problematic, particularly when plasma protein binding is high. The following work explores simultaneous assessment of both clearance processes, focusing on a commercial hepatocyte-fibroblast co-culture system (HμREL) over a 24-hour period using six probe drugs (ranging in metabolic and transporter clearance and low-to-high plasma protein binding). A rat hepatocyte co-culture assay was established using drug depletion (measuring both medium and total concentrations) and cell uptake kinetic analysis, both in the presence and absence of plasma protein (1% bovine serum albumin). Secretion of endogenous albumin was monitored as a marker of viability, and this reached 0.004% in incubations (at a rate similar to in vivo synthesis). Binding to stromal cells was substantial and required appropriate correction factors. Drug concentration-time courses were analyzed both by conventional methods and a mechanistic cell model prior to in vivo extrapolation. Clearance assayed by drug depletion in conventional suspended rat hepatocytes provided a benchmark to evaluate co-culture value. Addition of albumin appeared to improve predictions for some compounds (where fraction unbound in the medium is less than 0.1); however, for high-binding drugs, albumin significantly limited quantification and thus predictions. Overall, these results highlight ongoing challenges concerning in vitro hepatocyte system complexity and limitations of practical expediency. Considering this, more reliable measurement of hepatically cleared compounds seems possible through judicious use of available hepatocyte systems, including co-culture systems, as described herein; this would include those compounds with low metabolic turnover but high active uptake clearance. SIGNIFICANCE STATEMENT: Co-culture systems offer a more advanced tool than standard hepatocytes, with the ability to be cultured for longer periods of time, yet their potential as an in vitro tool has not been extensively assessed. We evaluate the strengths and limitations of the HμREL system using six drugs representing various metabolic and transporter-mediated clearance pathways with various degrees of albumin binding. Studies in the presence/absence of albumin allow in vitro-in vivo extrapolation and a framework to maximize their utility.

Reproducibility and Robustness of a Liver Microphysiological System PhysioMimix LC12 under Varying Culture Conditions and Cell Type Combinations

The liver is one of the key organs for exogenous and endogenous metabolism and is often a target for drug- and chemical-driven toxicity. A wide range of experimental approaches has been established to model and characterize the mechanisms of drug- and chemical-induced hepatotoxicity. A number of microfluidics-enabled in vitro models of the liver have been developed, but the unclear translatability of these platforms has hindered their adoption by the pharmaceutical industry; to achieve wide use for drug and chemical safety evaluation, demonstration of reproducibility and robustness under various contexts of use is required. One of these commercially available platforms is the PhysioMimix LC12, a microfluidic device where cells are seeded into a 3D scaffold that is continuously perfused with recirculating cell culture media to mimic liver sinusoids. Previous studies demonstrated this model's functionality and potential applicability to preclinical drug development. However, to gain confidence in PhysioMimix LC12's robustness and reproducibility, supplementary characterization steps are needed, including the assessment of various human hepatocyte sources, contribution of non-parenchymal cells (NPCs), and comparison to other models. In this study, we performed replicate studies averaging 14 days with either primary human hepatocytes (PHHs) or induced pluripotent stem cell (iPSC)-derived hepatocytes, with and without NPCs. Albumin and urea secretion, lactate dehydrogenase, CYP3A4 activity, and metabolism were evaluated to assess basal function and metabolic capacity. Model performance was characterized by different cell combinations under intra- and inter-experimental replication and compared to multi-well plates and other liver platforms. PhysioMimix LC12 demonstrated the highest metabolic function with PHHs, with or without THP-1 or Kupffer cells, for up to 10-14 days. iPSC-derived hepatocytes and PHHs co-cultured with additional NPCs demonstrated sub-optimal performance. Power analyses based on replicate experiments and different contexts of use will inform future study designs due to the limited throughput and high cell demand. Overall, this study describes a workflow for independent testing of a complex microphysiological system for specific contexts of use, which may increase end-user adoption in drug development.

Gelatin-Based Hybrid Hydrogel Scaffolds: Toward Physicochemical Liver Mimicry

There exists a clear need to develop novel materials that could serve liver tissue engineering purposes. Those materials need to be researched for the development of bioengineered liver tissue as an alternative to donor livers, as well as for materials that could be applied for scaffolds to develop an in vitro model for drug-induced liver injury (DILI) detection . In this paper, the hydrogels oxidized dextran-gelatin (Dexox-Gel) and norbornene-modified dextran-thiolated gelatin (DexNB-GelSH) were developed, and their feasibility toward processing via indirect 3D-printing was investigated with the aim to develop hydrogel scaffolds that physicochemically mimic native liver tissue. Furthermore, their in vitro biocompatibility was assessed using preliminary biological tests using HepG2 cells. Both materials were thoroughly physicochemically characterized and benchmarked to the methacrylated gelatin (GelMA) reference material. Due to inferior properties, Dexox-gel was not further processed into 3D-hydrogel scaffolds. This research revealed that DexNB-GelSH exhibited physicochemical properties that were in excellent agreement with the properties of natural liver tissue in contrast to GelMA. In combination with an equally good biological evaluation of DexNB-GelSH in comparison with GelMA based on an MTS proliferation assay and an albumin quantification assay, DexNB-GelSH can be considered promising in the field of liver tissue engineering.

Primary human hepatocytes-laden scaffolds for the treatment of acute liver failure

Cell-based liver therapies based on retrieving and steadying failed metabolic function(s) for acute and chronic diseases could be a valuable substitute for liver transplants, even though they are limited by the low engraftment capability and reduced functional quality of primary human hepatocytes (PHH). In this paper we propose the use of gelatin-hyaluronic acid (Gel-HA) scaffolds seeded with PHH for the treatment of liver failure. We first optimized the composition using Gel-HA hydrogels, looking for the mechanical properties closer to the human liver and determining HepG2 cells functionality. Gel-HA scaffolds with interconnected porosity (pore size 102 μm) were prepared and used for PHH culture and evaluation of key hepatic functions. PHH cultured in Gel-HA scaffolds exhibited increased albumin and urea secretion and metabolic capacity (CYP and UGT activity levels) compared to standard monolayer cultures. The transplant of the scaffold containing PHH led to an improvement in liver function (transaminase levels, necrosis) and ameliorated damage in a mouse model of acetaminophen (APAP)-induced liver failure. The study provided a mechanistic understanding of APAP-induced liver injury and the impact of transplantation by analyzing cytokine production and oxidative stress induction to find suitable biomarkers of cell therapy effectiveness.

The Influence of Sex Hormones in Liver Function and Disease

The liver performs a multitude of bodily functions, whilst retaining the ability to regenerate damaged tissue. In this review, we discuss sex steroid biology, regulation of mammalian liver physiology and the development of new model systems to improve our understanding of liver biology in health and disease. A major risk factor for the development of liver disease is hepatic fibrosis. Key drivers of this process are metabolic dysfunction and pathologic activation of the immune system. Although non-alcoholic fatty liver disease (NAFLD) is largely regarded as benign, it does progress to non-alcoholic steatohepatitis in a subset of patients, increasing their risk of developing cirrhosis and hepatocellular carcinoma. NAFLD susceptibility varies across the population, with obesity and insulin resistance playing a strong role in the disease development. Additionally, sex and age have been identified as important risk factors. In addition to the regulation of liver biochemistry, sex hormones also regulate the immune system, with sexual dimorphism described for both innate and adaptive immune responses. Therefore, sex differences in liver metabolism, immunity and their interplay are important factors to consider when designing, studying and developing therapeutic strategies to treat human liver disease. The purpose of this review is to provide the reader with a general overview of sex steroid biology and their regulation of mammalian liver physiology.

Unveiling hepatotoxicity distinction of coumarin-related compounds from glycosides to aglycones in Fructus Psoraleae by integrating UPLC-Q-TOF-MS and high content analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Fructus Psoraleae (FP), the dried and ripe fruit of Cullen corylifolium (L.) Medik., is widely used due to its various clinical pharmacological effects, but its hepatotoxicity restricts its clinical application. So far, its hepatotoxic components and their underlying mechanism have not been systematically elucidated.

AIM OF THE STUDY

This study was undertaken to reveal the hepatotoxicity distinction of coumarin-related compounds from glycosides to aglycones in FP and elucidate their potential mechanism.

METHODS

Rats were administrated with the aqueous extract of Fructus Psoraleae (AEFP), in which eight coumarin-related compounds were focused. Subsequently, compounds exposed in rats' livers were detected by UPLC-Q-TOF-MS, and the identified hepatotoxic compounds were evaluated to elaborate their possible mechanism by the aid of high content analysis (HCA).

RESULTS

Eight coumarin-related compounds were identified, among which psoralenoside (PO), isopsoralenoside (IPO), psoralen (P), and isopsoralen (IP) were the principally exposed compounds in rats' livers. Furocoumarinic acid glucoside (FAG), (E)-3-(4-(((2S, 3R, 4S, 5S, 6R)-3,4,5-trihydroxy-6-(hydroxymethyl) tetrahydro-2H-pyran-2-yl) oxy) benzofuran-5-yl) acrylic acid (isofurocoumarinic acid glucoside, IFAG), furocoumarinic acid (FA), and (E)-3-(4-hydroxybenzofuran-5-yl) acrylic acid (isofurocoumarinic acid, IFA) were also detected in low abundance. P, IP, FA, and IFA were identified as the hepatotoxic compounds, while their glycosides were almost non-hepatotoxic. The HCA's results showed that hepatotoxic compounds disrupted the balance in reactive oxygen species (ROS), nuclear area, and mitochondrial membrane potential of HepG2 cells, leading to the occurrence of hepatotoxicity.

CONCLUSIONS

P, IP, FA, and IFA were identified as hepatotoxic compounds, from which P and IP were proposed as the important risk components for hepatotoxicity. The conversion from glycosides to aglycones played an essential role in FP-induced hepatotoxicity.

Effects of Nelumbonucifera Gaertn. Petal Tea Extract on Hepatotoxicity and Oxidative Stress Induced by Mancozeb in Rat Model

Mancozeb (Mz) is one of the most widely used pesticides that has been reported to cause adverse human health risks. White Nelumbo nucifera (N. nucifera) petals have therapeutic properties to prevent toxicity. Hence, this study attempted to determine the effects of N. nucifera extract on hepatotoxicity and oxidative stress in mancozeb-treated rats. Seventy-two male rats were divided into nine groups and designed with a control; N. nucifera extract was administered at the doses of 0.55, 1.1, and 2.2 mg/kg bw/day, Mz was administered at 500 mg/kg bw/day, and the co-treatment groups (N. nucifera and Mz) were administered 0.55, 1.1, and 2.2 mg/kg bw/day of N. nucifera followed by administering Mz 500 mg/kg bw/day daily for 30 days. The results showed that all doses of N. nucifera extract did not induce hepatic toxicity and could suppress the toxicity of mancozeb by increasing body weight gain and decreasing relative liver weight, lobular inflammation, and total injury score. The combination treatment also decreased the molecular markers of oxidative stress (2-hydroxybutyric acid, 4-hydroxynonenal, l-tyrosine, pentosidine, and N6-carboxymethyllysine). Furthermore, the reduced glutathione and oxidized glutathione contents were adjusted close to the normal level. Therefore, N. nucifera extract is a natural antioxidant supplement that could decrease the toxicity of mancozeb and can be safely consumed.

Identification of indocyanine green as a STT3B inhibitor against mushroom α-amanitin cytotoxicity

The "death cap", Amanita phalloides, is the world's most poisonous mushroom, responsible for 90% of mushroom-related fatalities. The most fatal component of the death cap is α-amanitin. Despite its lethal effect, the exact mechanisms of how α-amanitin poisons humans remain unclear, leading to no specific antidote available for treatment. Here we show that STT3B is required for α-amanitin toxicity and its inhibitor, indocyanine green (ICG), can be used as a specific antidote. By combining a genome-wide CRISPR screen with an in silico drug screening and in vivo functional validation, we discover that N-glycan biosynthesis pathway and its key component, STT3B, play a crucial role in α-amanitin toxicity and that ICG is a STT3B inhibitor. Furthermore, we demonstrate that ICG is effective in blocking the toxic effect of α-amanitin in cells, liver organoids, and male mice, resulting in an overall increase in animal survival. Together, by combining a genome-wide CRISPR screen for α-amanitin toxicity with an in silico drug screen and functional validation in vivo, our study highlights ICG as a STT3B inhibitor against the mushroom toxin.

Molinate induces organ defects by promoting apoptosis, inflammation, and endoplasmic reticulum stress during the developmental stage of zebrafish

Molinate is classified as a thiocarbamate herbicide and is mainly used in paddy fields to culture rice. However, the toxic effects of molinate and the associated mechanisms in the process of development have not been completely elucidated. Therefore, in the present study, we demonstrated that molinate reduced the viability of zebrafish larvae and the probability of successful hatching using zebrafish (Danio rerio), one of the remarkable in vivo models for testing the toxicity of chemicals. In addition, molinate treatment triggered the occurrence of apoptosis, inflammation, and endoplasmic reticulum (ER) stress response in zebrafish larvae. Furthermore, we identified that an abnormal cardiovascular phenotype through wild type zebrafish, neuronal defects through transgenic olig2:dsRed zebrafish, and developmental toxicity in the liver through transgenic lfabp:dsRed zebrafish. Collectively, these results provide evidence of the hazardous effects of molinate on the developmental stage of non-target organisms by elucidating the toxic mechanisms of molinate in developing zebrafish.

Liver three-dimensional cellular models for high-throughput chemical testing

Drug-induced hepatotoxicity is a leading cause of drug withdrawal from the market. High-throughput screening utilizing in vitro liver models is critical for early-stage liver toxicity testing. Traditionally, monolayer human hepatocytes or immortalized liver cell lines (e.g., HepG2, HepaRG) have been used to test compound liver toxicity. However, monolayer-cultured liver cells sometimes lack the metabolic competence to mimic the in vivo condition and are therefore largely appropriate for short-term toxicological testing. They may not, however, be adequate for identifying chronic and recurring liver damage caused by drugs. Recently, several three-dimensional (3D) liver models have been developed. These 3D liver models better recapitulate normal liver function and metabolic capacity. This review describes the current development of 3D liver models that can be used to test drugs/chemicals for their pharmacologic and toxicologic effects, as well as the advantages and limitations of using these 3D liver models for high-throughput screening.

A Human Ovarian Tumor & Liver Organ-on-Chip for Simultaneous and More Predictive Toxo-Efficacy Assays

In oncology, the poor success rate of clinical trials is becoming increasingly evident due to the weak predictability of preclinical assays, which either do not recapitulate the complexity of human tissues (i.e., in vitro tests) or reveal species-specific outcomes (i.e., animal testing). Therefore, the development of novel approaches is fundamental for better evaluating novel anti-cancer treatments. Here, a multicompartmental organ-on-chip (OOC) platform was adopted to fluidically connect 3D ovarian cancer tissues to hepatic cellular models and resemble the systemic cisplatin administration for contemporarily investigating drug efficacy and hepatotoxic effects in a physiological context. Computational fluid dynamics was performed to impose capillary-like blood flows and predict cisplatin diffusion. After a cisplatin concentration screening using 2D/3D tissue models, cytotoxicity assays were conducted in the multicompartmental OOC and compared with static co-cultures and dynamic single-organ models. A linear decay of SKOV-3 ovarian cancer and HepG2 liver cell viability was observed with increasing cisplatin concentration. Furthermore, 3D ovarian cancer models showed higher drug resistance than the 2D model in static conditions. Most importantly, when compared to clinical therapy, the experimental approach combining 3D culture, fluid-dynamic conditions, and multi-organ connection displayed the most predictive toxicity and efficacy results, demonstrating that OOC-based approaches are reliable 3Rs alternatives in preclinic.

Evaluation of drug carrier hepatotoxicity using primary cell culture models

This study aims to establish a primary rat hepatocyte culture model to evaluate dose-dependent hepatotoxic effects of drug carriers (lipopolymer nanoparticles; LPNs) temporal. Primary rat hepatocyte cell cultures were used to determine half-maximal Inhibition Concentrations (IC50) of the drug-carrier library. Drug-carrier library, at concentrations <50 μg/mL, is benign to primary rat hepatocytes as determined using albumin and urea secretions. Albumin, as a hepatic biomarker, exhibited a more sensitive and faster outcome, compared to urea, for the determination of the IC50 value of LPNs. Temporal measurements of hepatic biomarkers including urea and albumin, and rigorous physicochemical (hydrodynamic diameter, surface charge, etc.) characterization, should be combined to evaluate the hepatotoxicity of drug carrier libraries in screens.

Recent advances in liver-on-chips: Design, fabrication, and applications

The liver is a multifunctional organ and the metabolic center of the human body. Most drugs and toxins are metabolized in the liver, resulting in varying degrees of hepatotoxicity. The damage of liver will seriously affect human health, so it is very important to study the prevention and treatment of liver diseases. At present, there are many research studies in this field. However, most of them are based on animal models, which are limited by the time-consuming processes and species difference between human and animals. In recent years, liver-on-chips have emerged and developed rapidly and are expected to replace animal models. Liver-on-chips refer to the use of a small number of liver cells on the chips to simulate the liver microenvironment and ultrastructure in vivo. They hold extensive applications in multiple fields by reproducing the unique physiological functions of the liver in vitro. In this review, we first introduced the physiology and pathology of liver and then described the cell system of liver-on-chips, the chip-based liver models, and the applications of liver-on-chips in liver transplantation, drug screening, and metabolic evaluation. Finally, we discussed the currently encountered challenges and future trends in liver-on-chips.

Cryopreservation of Liver-Cell Spheroids with Macromolecular Cryoprotectants

Spheroids are a powerful tool for basic research and to reduce or replace in vivo (animal) studies but are not routinely banked nor shared. Here, we report the successful cryopreservation of hepatocyte spheroids using macromolecular (polyampholyte) cryoprotectants supplemented into dimethyl sulfoxide (DMSO) solutions. We demonstrate that a polyampholyte significantly increases post-thaw recovery, minimizes membrane damage related to cryo-injury, and remains in the extracellular space making it simple to remove post-thaw. In a model toxicology challenge, the thawed spheroids matched the performance of fresh spheroids. F-actin staining showed that DMSO-only cryopreserved samples had reduced actin polymerization, which the polyampholyte rescued, potentially linked to intracellular ice formation. This work may facilitate access to off-the-shelf and ready-to-use frozen spheroids, without the need for in-house culturing. Readily accessible 3-D cell models may also reduce the number of in vivo experiments.

Hep3Gel: A Shape-Shifting Extracellular Matrix-Based, Three-Dimensional Liver Model Adaptable to Different Culture Systems

Drug-induced hepatotoxicity is a leading cause of clinical trial withdrawal. Therefore, in vitro modeling the hepatic behavior and functionalities is not only crucial to better understand physiological and pathological processes but also to support drug development with reliable high-throughput platforms. Different physiological and pathological models are currently under development and are commonly implemented both within platforms for standard 2D cultures and within tailor-made chambers. This paper introduces Hep3Gel: a hybrid alginate-extracellular matrix (ECM) hydrogel to produce 3D in vitro models of the liver, aiming to reproduce the hepatic chemomechanical niche, with the possibility of adapting its shape to different manufacturing techniques. The ECM, extracted and powdered from porcine livers by a specifically set-up procedure, preserved its crucial biological macromolecules and was embedded within alginate hydrogels prior to crosslinking. The viscoelastic behavior of Hep3Gel was tuned, reproducing the properties of a physiological organ, according to the available knowledge about hepatic biomechanics. By finely tuning the crosslinking kinetics of Hep3Gel, its dualistic nature can be exploited either by self-spreading or adapting its shape to different culture supports or retaining the imposed fiber shape during an extrusion-based 3D-bioprinting process, thus being a shape-shifter hydrogel. The self-spreading ability of Hep3Gel was characterized by combining empirical and numerical procedures, while its use as a bioink was experimentally characterized through rheological a priori printability evaluations and 3D printing tests. The effect of the addition of the ECM was evident after 4 days, doubling the survival rate of cells embedded within control hydrogels. This study represents a proof of concept of the applicability of Hep3Gel as a tool to develop 3D in vitro models of the liver.

Serum-Free Production of Human Stem Cell-Derived Liver Spheres for Cancer Metastasis Research

Renewable and scalable human liver tissue platforms are a powerful tool to study organ physiology and model diseases, such as cancer. Stem cell-derived models provide an alternative to cell lines, which can display limited relevance to primary cells and tissue. Historically, two-dimensional (2D) cultures have been used to model liver biology as they are easy to scale and deploy. However, 2D liver models lack functional diversity and phenotypic stability in long-term culture. To address those issues, protocols for generating the three-dimensional (3D) tissue aggregates have been developed. Here, we describe a methodology to generate 3D liver spheres from pluripotent stem cells. Liver spheres are composed of three key liver cell types (hepatic progenitor cells, endothelial cells, and hepatic stellate cells) and have been used to study human cancer cell metastasis.

A review of challenges and prospects of 3D cell-based culture models used for studying drug induced liver injury during early phases of drug development

Drug-induced liver injury (DILI) is the leading cause of compound attrition during drug development. Over the years, a battery of in-vitro cell culture toxicity tests is being conducted to evaluate the toxicity of compounds prior to testing in laboratory animals. Two-dimensional (2D) in-vitro cell culture models are commonly used and have provided a great deal of knowledge; however, these models often fall short in mimicking natural structures of tissues in-vivo. Testing in humans is the most logical method, but unfortunately there are ethical limitations associated with human tests. To overcome these limitations better human-relevant, predictive models are required. The past decade has witnessed significant efforts towards the development of three-dimensional (3D) in-vitro cell culture models better mimicking in-vivo physiology. 3D cell culture has advantages in being representative of the interactions of cells in-vivo and when validated can act as an interphase between 2D cell culture models and in-vivo animal models. The current review seeks to provide an overview of the challenges that make biomarkers used for detection of DILI not to be sensitive enough during drug development and explore how 3D cell culture models can be used to address the gap with the current models.

Oxyberberrubine, a novel liver microsomes-mediated secondary metabolite of berberine, alleviates hyperuricemic nephropathy in mice

BACKGROUND

Berberrubine (BRB), one of the major metabolites of berberine (BBR), exerts an anti-hyperuricemic effect even superior to BBR. Liver is an important location for drug transformation. Nevertheless, there are few studies on the bioactivities and metabolites of BRB.

PURPOSE

We investigated whether oxyberberrubine (OBR), a liver metabolite of BRB, exerted urate-lowering and reno-protective effects in hyperuricemic mice.

METHODS

Liver microsomes were used to incubate BRB for studying its biotransformation. We isolated and identified its new metabolite OBR, and investigated its anti-hyperuricemic and reno-protective effects. In this work, the hyperuricemic mice model was established by receiving potassium oxonate (PO) and hypoxanthine (HX) for 7 consecutive days. 1 h after modeling, different dosages of OBR (5, 10 and 20 mg/kg), BRB (20 mg/kg) or febuxostat (Fex, 5 mg/kg) were given mice by gavage.

RESULTS

Results showed that OBR possessed potent anti-hyperuricemic and reno-protective effects in hyperuricemic mice. Serum uric acid (UA) level was lowered, and the activities of xanthine oxidase (XOD) as well as adenosine deaminase (ADA) in the liver were suppressed after treatment with OBR. Hepatic expressions of XOD were remarkably decreased at mRNA and protein levels by OBR treatment. In addition, OBR prominently alleviated renal injury, embodied in markedly reduced serum creatinine and blood urea nitrogen (BUN) levels, decreased inflammatory mediators (TNF-α, IL-1β, IL-6 and IL-18) levels, mRNA expression of CYP27B1 and repairment of renal tissues damage. Besides, OBR down-regulated renal expression of urate transporter 1 (URAT1), glucose transporter 9 (GLUT9), NOD-like receptor 3 (NLRP3), apoptosis-associated speck-like protein containing CARD (ASC), and caspase-1 at mRNA and protein levels.

CONCLUSIONS

In short, our study indicated that OBR possessed superior anti-hyperuricemic and reno-protective effects, at least in part, through the inhibition of XOD, URAT1, GLUT9 and NLRP3 inflammasome signaling pathway in the kidney.

Human health risk assessment of cinnamate UV absorbers: In vitro and in silico investigations

Organic UV absorbers (UVAs) are contaminants of emerging concern. Environmental persistence and potential toxicological enrichment studies of UVAs have attracted international concern. It is important to study the toxicity mechanism of UVAs. This study is the first to report the toxicological mechanism of two cinnamate UV absorbers (CUVAs), 2-ethyl 4-methoxycinnamate (OMC) and isoamyl 4-methoxycinnamate (IMC) based on cellular models and molecular models. Cellular models demonstrated that the CUVAs-induced apoptosis might be associated with cellular mitochondrial damage pathways. The results of molecular models showed that OMC and IMC could affect the binding between major proteins and enzymes in the mitochondrial damage pathway and contaminants, ultimately leading to apoptosis. The cellular-molecular models showed that IMC and OMC have dose-effect relationships on cytotoxicity. The composite model is more informative than a single model. This study further indicate that UVAs causes toxicology effects that have implications for the environment and human health.