Micropatterned Coculture With 3T3-J2 Fibroblasts Enhances Hepatic Functions and Drug Screening Utility of HepaRG Cells

Control Compounds for Preclinical Drug-Induced Liver Injury Assessment: Consensus-driven systematic review by the ProEuroDILI Network

BACKGROUND & AIMS

Idiosyncratic drug-induced liver injury (DILI) is a complex and unpredictable event caused by drugs, herbal or dietary supplements. Early identification of human hepatotoxicity at preclinical stages remains a major challenge, in which the selection of validated in vitro systems and test drugs has a significant impact. This systematic review analyzed the compounds used in hepatotoxicity assays and established a list of DILI positive and negative control drugs for validation of in vitro models of DILI, supported by literature and clinical evidence and endorsed by an expert committee from COST Action ProEuroDILI Network (CA17112).

METHODS

Following 2020 PRISMA guidelines, original research articles focusing on DILI which used in vitro human models and performed at least one hepatotoxicity assay with positive and negative control compounds, were included. Bias of the studies was assessed by a modified 'Toxicological Data Reliability Assessment Tool'.

RESULTS

51 studies (out of 2,936) met the inclusion criteria, with 30 categorized as reliable without restrictions. Although there was a broad consensus on positive compounds, the selection of negative compounds lacked clarity. 2D monoculture, short exposure times and cytotoxicity endpoints were the most tested, although there was no consensus on the drug concentrations.

CONCLUSIONS

The extensive analysis highlighted the lack of agreement on control compounds for in vitro DILI assessment. Following comprehensive in vitro and clinical data analysis together with input from the expert committee, an evidence-based consensus-driven list of 10 positive and negative drugs is proposed for validating in vitro models for improving preclinical drug safety testing regimes.

IMPACT AND IMPLICATIONS

Prediction of human toxicity early in the drug development process remains a major challenge. For this, human in vitro models are becoming increasingly important, however, the development of more physiologically relevant liver models and careful selection of control DILI+ and DILI- drugs are requisites to better predict DILI liability of new drug candidates. Thus, this systematic study holds critical implications for standardizing validation of new in vitro models for studying drug-induced liver injury (DILI). By establishing a consensus-driven list of positive and negative control drugs, the study provides a scientifically justified framework for enhancing the consistency of preclinical testing, thereby addressing a significant challenge in early hepatotoxicity identification. The results are of paramount importance to all the actors involved in the drug development process, offering a standardized approach to assess hepatotoxic risks. Practically, these findings can guide researchers in evaluating safety profiles of new drugs, refining in vitro models, and informing regulatory agencies on potential improvements to regulatory guidelines, ensuring a more systematic and efficient approach to drug safety assessment.

Assessing bioartificial organ function: the 3P model framework and its validation

The rapid advancement in the fabrication and culture of in vitro organs has marked a new era in biomedical research. While strides have been made in creating structurally diverse bioartificial organs, such as the liver, which serves as the focal organ in our study, the field lacks a uniform approach for the predictive assessment of liver function. Our research bridges this gap with the introduction of a novel, machine-learning-based "3P model" framework. This model draws on a decade of experimental data across diverse culture platform studies, aiming to identify critical fabrication parameters affecting liver function, particularly in terms of albumin and urea secretion. Through meticulous statistical analysis, we evaluated the functional sustainability of the in vitro liver models. Despite the diversity of research methodologies and the consequent scarcity of standardized data, our regression model effectively captures the patterns observed in experimental findings. The insights gleaned from our study shed light on optimizing culture conditions and advance the evaluation of the functional maintenance capacity of bioartificial livers. This sets a precedent for future functional evaluations of bioartificial organs using machine learning.

Developing Liver Microphysiological Systems for Biomedical Applications

Microphysiological systems (MPSs), also known as organ chips, are micro-units that integrate cells with diverse physical and biochemical environmental cues. In the field of liver MPSs, cellular components have advanced from simple planar cell cultures to more sophisticated 3D formations such as spheroids and organoids. Additionally, progress in microfluidic devices, bioprinting, engineering of matrix materials, and interdisciplinary technologies have significant promise for producing MPSs with biomimetic structures and functions. This review provides a comprehensive summary of biomimetic liver MPSs including their clinical applications and future developmental potential. First, the key components of liver MPSs, including the principal cell types and engineered structures utilized for cell cultivation, are briefly introduced. Subsequently, the biomedical applications of liver MPSs, including the creation of disease models, drug absorption, distribution, metabolism, excretion, and toxicity, are discussed. Finally, the challenges encountered by MPSs are summarized, and future research directions for their development are proposed.

Mera: A scalable high throughput automated micro-physiological system

There is an urgent need for scalable Microphysiological Systems (MPS's)1 that can better predict drug efficacy and toxicity at the preclinical screening stage. Here we present Mera, an automated, modular and scalable system for culturing and assaying microtissues with interconnected fluidics, inbuilt environmental control and automated image capture. The system presented has multiple possible fluidics modes. Of these the primary mode is designed so that cells may be matured into a desired microtissue type and in the secondary mode the fluid flow can be re-orientated to create a recirculating circuit composed of inter-connected channels to allow drugging or staining. We present data demonstrating the prototype system Mera using an Acetaminophen/HepG2 liver microtissue toxicity assay with Calcein AM and Ethidium Homodimer (EtHD1) viability assays. We demonstrate the functionality of the automated image capture system. The prototype microtissue culture plate wells are laid out in a 3 × 3 or 4 × 10 grid format with viability and toxicity assays demonstrated in both formats. In this paper we set the groundwork for the Mera system as a viable option for scalable microtissue culture and assay development.

Engineered Platforms for Maturing Pluripotent Stem Cell-Derived Liver Cells for Disease Modeling

Several liver diseases (eg, hepatitis B/C viruses, alcoholic/nonalcoholic fatty liver, malaria, monogenic diseases, and drug-induced liver injury) significantly impact global mortality and morbidity. Species-specific differences in liver functions limit the use of animals to fully elucidate/predict human outcomes; therefore, in vitro human liver models are used for basic and translational research to complement animal studies. However, primary human liver cells are in short supply and display donor-to-donor variability in viability/quality. In contrast, human hepatocyte-like cells (HLCs) differentiated from induced pluripotent stem cells and embryonic stem cells are a near infinite cell resource that retains the patient/donor's genetic background; however, conventional protocols yield immature phenotypes. HLC maturation can be significantly improved using advanced techniques, such as protein micropatterning to precisely control cell-cell interactions, controlled sized spheroids, organoids with multiple cell types and layers, 3-dimensional bioprinting to spatially control cell populations, microfluidic devices for automated nutrient exchange and to induce liver zonation via soluble factor gradients, and synthetic biology to genetically modify the HLCs to accelerate and enhance maturation. Here, we present design features and characterization for representative advanced HLC maturation platforms and then discuss HLC use for modeling various liver diseases. Lastly, we discuss desirable advances to move this field forward. We anticipate that with continued advances in this space, pluripotent stem cell-derived liver models will provide human-relevant data much earlier in preclinical drug development and reduce animal usage, help elucidate liver disease mechanisms for the discovery of efficacious and safe therapeutics, and be useful as cell-based therapies for patients suffering from end-stage liver failure.

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.

Study on the associations between liver damage and antituberculosis drug rifampicin and relative metabolic enzyme gene polymorphisms

The occurrence of antituberculosis drug-induced liver injury affects the effectiveness of antituberculosis treatments. Understanding the mechanism and risk factors of such liver injury may improve the outcomes of those patients who received antituberculosis treatments. In this study, 2,255 pulmonary tuberculosis patients were included. Their medical records were reviewed, questionnaire surveys, liver function tests at the end of February (including patients with uncomfortable symptoms during the intensive treatment period), and blood samples were saved. Afterward, cases of liver damage were determined using Chinese liver damage criteria. The genotype of all participants was determined using the PCR-LDR method. Finally, the association between genetic polymorphism and ATB-DILI susceptibility was assessed using the univariate Logistic regression models. Among the 2,255 tuberculosis patients who received rifampicin, 612 (27.1%) had antituberculosis drug-induced liver injury. We observed higher proportions of older age, male, and lower levels of AST, ALT, and TBil among patients with liver injury. Results of univariate of logistic regression models showed that patients with CYP2C19 were more likely to have liver injury compared with no such genotypes patients (all P < 0.05). Patients with tuberculosis with older age and genetic polymorphism of CYP3A4, CYP2C9, and CYP2C19 who received long-term rifampicin treatment were more likely to have antituberculosis drug-induced liver injury. It is important for healthcare providers to carefully evaluate and monitor rifampicin use for these patients.

Bioengineered Liver Models for Investigating Disease Pathogenesis and Regenerative Medicine

Owing to species-specific differences in liver pathways, in vitro human liver models are utilized for elucidating mechanisms underlying disease pathogenesis, drug development, and regenerative medicine. To mitigate limitations with de-differentiated cultures, bioengineers have developed advanced techniques/platforms, including micropatterned cocultures, spheroids/organoids, bioprinting, and microfluidic devices, for perfusing cell cultures and liver slices. Such techniques improve mature functions and culture lifetime of primary and stem-cell human liver cells. Furthermore, bioengineered liver models display several features of liver diseases including infections with pathogens (e.g., malaria, hepatitis C/B viruses, Zika, dengue, yellow fever), alcoholic/nonalcoholic fatty liver disease, and cancer. Here, we discuss features of bioengineered human liver models, their uses for modeling aforementioned diseases, and how such models are being augmented/adapted for fabricating implantable human liver tissues for clinical therapy. Ultimately, continued advances in bioengineered human liver models have the potential to aid the development of novel, safe, and efficacious therapies for liver disease.

Latest impact of engineered human liver platforms on drug development

Drug-induced liver injury (DILI) is a leading cause of drug attrition, which is partly due to differences between preclinical animals and humans in metabolic pathways. Therefore, in vitro human liver models are utilized in biopharmaceutical practice to mitigate DILI risk and assess related mechanisms of drug transport and metabolism. However, liver cells lose phenotypic functions within 1–3 days in two-dimensional monocultures on collagen-coated polystyrene/glass, which precludes their use to model the chronic effects of drugs and disease stimuli. To mitigate such a limitation, bioengineers have adapted tools from the semiconductor industry and additive manufacturing to precisely control the microenvironment of liver cells. Such tools have led to the fabrication of advanced two-dimensional and three-dimensional human liver platforms for different throughput needs and assay endpoints (e.g., micropatterned cocultures, spheroids, organoids, bioprinted tissues, and microfluidic devices); such platforms have significantly enhanced liver functions closer to physiologic levels and improved functional lifetime to >4 weeks, which has translated to higher sensitivity for predicting drug outcomes and enabling modeling of diseased phenotypes for novel drug discovery. Here, we focus on commercialized engineered liver platforms and case studies from the biopharmaceutical industry showcasing their impact on drug development. We also discuss emerging multi-organ microfluidic devices containing a liver compartment that allow modeling of inter-tissue crosstalk following drug exposure. Finally, we end with key requirements for engineered liver platforms to become routine fixtures in the biopharmaceutical industry toward reducing animal usage and providing patients with safe and efficacious drugs with unprecedented speed and reduced cost.

The methylimidazolium ionic liquid M8OI is detectable in human sera and is subject to biliary excretion in perfused human liver

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M8OI was recently found to be contaminating the environment.

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M8OI was detected in the sera from 5/20 PBC patients and 1/10 controls.

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M8OI is taken up by human liver hepatocytes.

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M8OI is sequentially metabolised by CYPs followed by oxidation by dehydrogenases.

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The final carboxylic acid metabolite COOH7IM is, in part, excreted into human bile.

A methylimidizolium ionic liquid (M8OI) was recently found to be contaminating the environment and to be related to and/or potentially a component of an environmental trigger for the autoimmune liver disease primary biliary cholangitis (PBC). The aims of this study were to investigate human exposure to M8OI, hepatic metabolism and excretion. PBC patient and control sera were screened for the presence of M8OI. Human livers were perfused with 50μM M8OI in a closed circuit and its hepatic disposition examined. Metabolism was examined in cultured human hepatocytes and differentiated HepaRG cells by the addition of M8OI and metabolites in the range 10–100 μM. M8OI was detected in the sera from 5/20 PBC patients and 1/10 controls. In perfused livers, M8OI was cleared from the plasma with its appearance – primarily in the form of its hydroxylated (HO8IM) and carboxylated (COOH7IM) products – in the bile. Metabolism was reflected in cultured hepatocytes with HO8IM production inhibited by the cytochrome P450 inhibitor ketoconazole. Further oxidation of HO8IM to COOH7IM was sequentially inhibited by the alcohol and acetaldehyde dehydrogenase inhibitors 4-methyl pyrazole and disulfiram respectively. Hepatocytes from 1 donor failed to metabolise M8OI to COOH7IM over a 24 h period. These results demonstrate exposure to M8OI in the human population, monooxygenation by cytochromes P450 followed by alcohol and acetaldehyde dehydrogenase oxidation to a carboxylic acid that are excreted, in part, via the bile in human liver.