StemPanTox: A fast and wide-target drug assessment system for tailor-made safety evaluations using personalized iPS cells.

An alternative model that reliably predicts human-specific toxicity is necessary because the translatability of effects on animal models for human disease is limited to context. Previously, we developed a method that accurately predicts developmental toxicity based on the gene networks of undifferentiated human embryonic stem (ES) cells. Here, we advanced this method to predict toxicities of 24 chemicals in six categories (neurotoxins, cardiotoxins, hepatotoxins, two types of nephrotoxins, and non-genotoxic carcinogens) and achieved high predictability (AUC = 0.

Evaluation of Parent- and Metabolite-Induced Mitochondrial Toxicities Using CYP-Introduced HepG2 cells.

Mitochondrial toxicity is an important factor to predict drug-induced liver injury (DILI). Previous studies have focused predominantly on mitochondrial toxicities due to parent forms, and no study has adequately evaluated metabolite-induced mitochondrial toxicity. Moreover, previous studies have used HepG2 cells, which lack many cytochrome P450 (CYP) genes.

Development of a next generation risk assessment framework for the evaluation of skin sensitisation of cosmetic ingredients.

All cosmetic products placed onto the market must undergo a risk assessment for human health to ensure they are safe for consumers, including an assessment of skin sensitisation risk. Historically, in vivo animal test methods were used to identify and characterise skin sensitisation hazard, however non-animal and other new approach methodologies (NAMs) are now the preferred and mandated choice for use in risk assessment for cosmetic ingredients. The experience gained over the last three decades on how to conduct risk assessments based upon NAMs has allowed us to develop a non-animal, next generation risk assessment (NGRA) framework for the assessment of skin sensitisers.

Hypoxia/reoxygenation exacerbates drug-induced cytotoxicity by opening mitochondrial permeability transition pore: Possible application for toxicity screening.

Recently, mitochondrial dysfunction is thought of as an important factor leading to a drug-induced liver injury. Our previous reports show that mitochondria-related toxicity, including respiratory chain inhibition (RCI) and reactive oxygen species (ROS) induction, can be detected by the modification of sugar resource substitution and high oxygen condition. However, this in vitro model does not detect mitochondrial permeability transition (MPT)-induced toxicity.

Mechanism-based integrated assay systems for the prediction of drug-induced liver injury.

Drug-induced liver injury (DILI) can cause hepatic failure and result in drug withdrawal from the market. It has host-related and compound-dependent mechanisms. Preclinical prediction of DILI risk is very challenging and safety assessments based on animals inadequately forecast human DILI risk.

Successful energy shift from glycolysis to mitochondrial oxidative phosphorylation in freshly isolated hepatocytes from humanized mice liver.

Mitochondrial toxicity is a factor of drug-induced liver injury. Previously, we reported an in vitro rat hepatocyte assay where mitochondrial toxicity was more sensitively evaluated, using sugar resource substitution and increased oxygen supply. Although this method could be applicable to human cell-based assay, cryopreserved human hepatocyte (CHH) has some disadvantages/uncertainty, including unstable same donor supply and potential organelle damage due to cryopreservation.

Functional modulation of liver mitochondria in lipopolysaccharide/drug co-treated rat liver injury model.

Drug-induced liver injury is not readily detectable using conventional animal studies during pre-clinical drug development. To address this problem, other researchers have proposed the use of co-administration of lipopolysaccharide (LPS), an endotoxin produced by gram-negative bacteria, and a drug. Using this approach, liver injury that is otherwise not detected following drug administration alone can be successfully identified.

Mild depolarization is involved in troglitazone-induced liver mitochondrial membrane permeability transition via mitochondrial iPLA activation.

Troglitazone, the first peroxisome proliferator-associated receptor γ agonist developed as an antidiabetic drug, was withdrawn from the market due to idiosyncratic severe liver toxicity. One proposed mechanism by which troglitazone causes liver injury is induction of mitochondrial membrane permeability transition (MPT), which occurs in a calcium-independent phospholipase A2 (iPLA)-dependent manner at a concentration of 10 µM. MPT, induced by opening of the MPT pore, leads to the release of cytochrome c and consequent apoptosis or necrosis.

In vitro bile acid-dependent hepatocyte toxicity assay system using human induced pluripotent stem cell-derived hepatocytes: Current status and disadvantages to overcome.

Cholestatic drug-induced liver injury (DILI) is a type of hepatotoxicity. Its underlying mechanisms are dysfunction of bile salt export pump (BSEP) and multidrug resistance-associated protein 2/3/4 (MRP2/3/4), which play major roles in bile acid (BA) excretion into the bile canaliculi and blood, resulting in accumulation of BAs in hepatocytes. The sandwich-cultured hepatocyte (SCH) model can simultaneously analyze hepatic uptake and biliary excretion.

Inhibition of biliary network reconstruction by benzbromarone delays recovery from pre-existing liver injury.

The liver performs a variety of essential functions; hence drug-induced liver injury (DILI) is a serious concern that can ultimately lead to the withdrawal of a drug from the market or discontinuation of drug development. However, the mechanisms of drug-induced liver injury are not always clear. We hypothesized that drugs may inhibit the liver recovery process, especially bile canalicular (BC) network reformation, leading to persistent liver injury and deterioration, and tested this hypothesis in the present work.

Synthesis of novel benzbromarone derivatives designed to avoid metabolic activation.

We synthesized six novel BBR derivatives that were designed to avoid metabolic activation via ipso-substitution and evaluated for their degree of toxicity and hURAT1 inhibition. It was found that all of the derivatives demonstrate lower cytotoxicity in mouse hepatocytes and lower levels of metabolic activation than BBR, while maintaining their inhibitory activity toward the uric acid transporter. We propose that these derivatives could serve as effective uricosuric agents that have much better safety profiles than BBR.

Increased susceptibility to troglitazone-induced mitochondrial permeability transition in type 2 diabetes mellitus model rat.

Troglitazone, a member of the thiazolidinedione class of antidiabetic drugs, was withdrawn from the market because it causes severe liver injury. One of the mechanisms for this adverse effect is thought to be mitochondrial toxicity. To investigate the characteristics of troglitazone-induced liver toxicity in more depth, the toxicological effects of troglitazone on hepatocytes and liver mitochondria were investigated using a rat model of type 2 diabetes mellitus (T2DM).

Evaluation of immune-mediated idiosyncratic drug toxicity using chimeric HLA transgenic mice.

Immune-mediated idiosyncratic drug toxicity (IDT) is a rare adverse drug reaction, potentially resulting in death. Although genome-wide association studies suggest that the occurrence of immune-mediated IDT is strongly associated with specific human leukocyte antigen (HLA) allotypes, these associations have not yet been prospectively demonstrated. In this study, we focused on HLA-B*57:01 and abacavir (ABC)-induced immune-mediated IDT, and constructed transgenic mice carrying chimeric HLA-B*57:01 (B*57:01-Tg) to determine if this in vivo model may be useful for evaluating immune-mediated IDT.

Identification of Bile Acids Responsible for Inhibiting the Bile Salt Export Pump, Leading to Bile Acid Accumulation and Cell Toxicity in Rat Hepatocytes.

Inhibition of bile salt export pump (BSEP) causes hepatic accumulation of toxic bile acid (BA), leading to hepatocyte death. We reported a sandwich-cultured hepatocyte (SCH)-based model that can estimate potential cholestatic compounds by assessing their ability to induce hepatotoxicity in combination with a titrated amount of human 12 BA species. However, there is little information about the specific BAs responsible for hepatotoxicity, when BSEP is inhibited.

Troglitazone Inhibits Bile Acid Amidation: A Possible Risk Factor for Liver Injury.

Troglitazone and pioglitazone were developed as thiazolidinedione-type antidiabetes drugs, but only troglitazone was withdrawn from the markets due to severe liver injury. As both troglitazone and its sulfate metabolite are strong inhibitors of the bile salt export pump (BSEP), troglitazone-induced bile acid (BA) retention is thought to be one of the underlying mechanisms of liver injury. However, pioglitazone is also a strong BSEP inhibitor, indicating other mechanisms may also be involved in troglitazone-induced BA retention.

Metabolic Activation of Cholestatic Drug-Induced Bile Acid-Dependent Toxicity in Human Sandwich-Cultured Hepatocytes.

We previously reported a cell-based toxicity assay using sandwich-cultured hepatocytes in combination with a titrated amount of human bile acid (BA) species. In this assay, test compound-induced inhibition of BA efflux from sandwich-cultured hepatocytes leads to BA-dependent cell toxicity (BA, i.e.

Use of Primary Rat Hepatocytes for Prediction of Drug-Induced Mitochondrial Dysfunction.

Mitochondrial dysfunction plays a central role in drug-induced liver injury. To evaluate drug-induced mitochondrial impairment, several isolated mitochondria- or cell line-based assays have been reported. Among them, culturing HepG2 cells in galactose provides a remarkable method to assess mitochondrial toxicity by activating mitochondrial aerobic respiration.

Inhibition of bile canalicular network formation in rat sandwich cultured hepatocytes by drugs associated with risk of severe liver injury.

Idiosyncratic drug-induced liver injury is a clinical concern with serious consequences. Although many preclinical screening methods have been proposed, it remains difficult to identify compounds associated with this rare but potentially fatal liver condition. Here, we propose a novel assay system to assess the risk of liver injury.

Assessment of mitochondrial dysfunction-related, drug-induced hepatotoxicity in primary rat hepatocytes.

Evidence that mitochondrial dysfunction plays a central role in drug-induced liver injury is rapidly accumulating. In contrast to physiological conditions, in which almost all adenosine triphosphate (ATP) in hepatocytes is generated in mitochondria via aerobic respiration, the high glucose content and limited oxygen supply of conventional culture systems force primary hepatocytes to generate most ATP via cytosolic glycolysis. Thus, such anaerobically poised cells are resistant to xenobiotics that impair mitochondrial function, and are not suitable to identify drugs with mitochondrial liabilities.

Establishment of a Drug-Induced, Bile Acid-Dependent Hepatotoxicity Model Using HepaRG Cells.

Bile acid (BA) retention within hepatocytes is an underlying mechanism of cholestatic drug-induced liver injury (DILI). We previously developed an assay using sandwich-cultured human hepatocytes (SCHHs) to evaluate drug-induced hepatocyte toxicity accompanying intracellular BA accumulation. However, due to shortcomings commonly associated with the use of primary human hepatocytes (e.

Prediction of the Clinical Risk of Drug-Induced Cholestatic Liver Injury Using an In Vitro Sandwich Cultured Hepatocyte Assay.

Drug-induced liver injury (DILI) is of concern to the pharmaceutical industry, and reliable preclinical screens are required. Previously, we established an in vitro bile acid-dependent hepatotoxicity assay that mimics cholestatic DILI in vivo. Here, we confirmed that this assay can predict cholestatic DILI in clinical situations by comparing in vitro cytotoxicity data with in vivo risk.

Pharmacokinetic Herb-Drug Interactions: Insight into Mechanisms and Consequences.

Herbal medicines are currently in high demand, and their popularity is steadily increasing. Because of their perceived effectiveness, fewer side effects and relatively low cost, they are being used for the management of numerous medical conditions. However, they are capable of affecting the pharmacokinetics and pharmacodynamics of coadministered conventional drugs.

Metabolic activation of hepatotoxic drug (benzbromarone) induced mitochondrial membrane permeability transition.

The risk of drug-induced liver injury (DILI) is of great concern to the pharmaceutical industry. It is well-known that metabolic activation of drugs to form toxic metabolites (TMs) is strongly associated with DILI onset. Drug-induced mitochondrial dysfunction is also strongly associated with increased risk of DILI.

Basal efflux of bile acids contributes to drug-induced bile acid-dependent hepatocyte toxicity in rat sandwich-cultured hepatocytes.

The bile salt export pump (BSEP or Bsep) functions as an apical transporter to eliminate bile acids (BAs) from hepatocytes into the bile. BSEP or Bsep inhibitors engender BA retention, suggested as an underlying mechanism of cholestatic drug-induced liver injury. We previously reported a method to evaluate BSEP-mediated BA-dependent hepatocyte toxicity by using sandwich-cultured hepatocytes (SCHs).