Development of human pluripotent stem cell-derived hepatic organoids as an alternative model for drug safety assessment.

Human in vitro hepatic models that faithfully recapitulate liver function are essential for successful basic and translational research. A limitation of current in vitro models, which are extensively used for drug discovery and toxicity testing, is the loss of drug metabolic function due to the low expression and activity of cytochrome P450 (CYP450) enzymes. Here, we aimed to generate human pluripotent stem cell-derived hepatic organoids (hHOs) with a high drug metabolic ability. We established a two-step protocol to produce hHOs from human pluripotent stem cells for long-term expansion and drug testing. Fully differentiated hHOs had multicellular composition and exhibited cellular polarity and hepatobiliary structures. They also displayed remarkable CYP450 activity and recapitulated the metabolic clearance, CYP450-mediated drug toxicity, and metabolism. Furthermore, hHOs successfully modeled Wilson's disease in terms of Cu metabolism, drug responses, and diagnostic marker expression and secretion. In conclusion, hHOs exhibit high capacity for drug testing and disease modeling. Hence, this hepatic model system provides an advanced tool for studying hepatic drug metabolism and diseases.

Preclinical safety assessment of a therapeutic human papillomavirus DNA vaccine combined with intravaginal interleukin-7 fused with hybrid Fc in female rats.

This study was conducted to establish the toxicological profile of combination treatment with therapeutic HPV DNA vaccines (GX-188E) and the long-acting form of recombinant human interleukin-7 fused with hybrid Fc (IL-7hyFc). GX-188E was administered intramuscularly by electroporation with or without IL-7hyFc intravaginally once per 2 weeks for 8 weeks (five times) in female Sprague-Dawley rats. Because up-regulation of immune responses and migration of antigen-specific T cells in cervicoviginal tissue were predicted as therapeutic effects, we distinguished adverse effects from therapeutic effects based on the severity of the systemic immune response, reversibility of lymphoid tissue changes, target tissue damage, and off-target immune responses. We observed that the number of neutrophils was increased, and the number of lymphocytes was decreased in the blood. Further, myofiber degeneration, necrosis, fibroplasia, and cell infiltration were observed at the GX-188E administration site. These changes were fully or partially recovered over a 4-week period. Analysis of lymphocytes in spleen revealed that CD4+ T cells and total T cells decreased in rats treated with GX-188E in combination with a high dose of IL-7hyFc (1.25 mg/animal). However, these changes were not considered adverse because they were transient and may have been related to electroporation-mediated DNA delivery or the local migration of lymphocytes induced by IL-7. Therefore, the potential toxicity of the combination of GX-188E and IL-7hyFc treatment was comparable to that of GX-188E treatment alone, and the no observed adverse effect level for GX-188E with IL-7hyFc was considered as 320 µg/animal for GX-188E and 1.25 mg/animal for IL-7hyFc.

In vitro and in vivo assessment of the genotoxic effects of ceric ammonium nitrate and 1,3-propane sultone.

A variety of methods have been developed for accurate and systematic evaluation of chemical genotoxicity. Ceric ammonium nitrate (CAN) and 1,3-propane sultone (1,3-PS) have been extensively applied in industrial fields. Although 1,3-PS, but not CAN, has been reported as a potent carcinogen, systematic assessment of the genotoxic properties of these chemicals has not been conducted. The purpose of this study was to establish a decision tree for evaluating genotoxicity based on the good laboratory practices (GLP) system using 1,3-PS and CAN as test chemicals. In vitro studies were performed including the bacterial reverse mutation assay, chromosomal aberration assay, and micronucleus assay. We conducted in vivo studies using a combined micronucleus and alkaline comet (MN-CMT) assay and the Pig-a gene mutation assay, which is a promising method for detecting gene mutations in vivo. CAN showed negative responses in all in vitro genotoxicity assays and the in vivo combined MN-CMT assay. Meanwhile, 1,3-PS had positive results in all in vitro and in vivo genotoxicity assays. In this study, we confirmed the genotoxicity of 1,3-PS and CAN using both in vitro and in vivo assays. We propose a decision tree for evaluating chemical-induced genotoxicity.

Determination of mesoridazine by liquid chromatography-tandem mass spectrometry and its application to pharmacokinetic study in rats.

The object of the present study was to develop and validate an assay method of mesoridazine in rat plasma using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Plasma samples from rats were prepared by simple protein precipitation and injected onto the LC-MS/MS system for quantification. Mesoridazine and chlorpromazine as an internal standard (IS) were separated by a reversed phase C18 column. A mobile phase was composed of 10mM ammonium formate in water and acetonitrile (ACN) (v/v) by a linear gradient system, increasing the percentage of ACN from 2% at 0.4min to 98% at 2.5min with 4min total run time. The ion transitions monitored in positive-ion mode [M+H](+) of multiple-reaction monitoring (MRM) were m/z 387>126 for mesoridazine and m/z 319>86 for IS. The detector response was specific and linear for mesoridazine at concentrations within the range 0.001-4µg/ml and the correlation coefficient (R(2)) was greater than 0.999 and the signal-to-noise ratios for the samples were ≥10. The intra- and inter-day precision and accuracy of the method were determined to be within the acceptance criteria for assay validation guidelines. The matrix effects were approximately 101 and 99.5% from rat plasma for mesoridazine and chlorpromazine, respectively. Mesoridazine was stable under various processing and/or handling conditions. Mesoridazine concentrations were readily measured in rat plasma samples after intravenous and oral administration. This assay method can be practically useful to the pharmacokinetic and/or toxicokinetic studies of mesoridazine.

Toxicity assessment of Leonuri Herba aqueous extract orally administered to rats for 13 consecutive weeks.

ETHNOPHARMACOLOGICAL RELEVANCE: The Leonuri Herba has been traditionally used for women's disease in Asian countries. AIM OF THE STUDY: The objective of the present study was to evaluate the subchronic toxicity of Leonuri Herba aqueous extract in male and female F344 rats. MATERIAL AND METHODS: Leonuri Herba aqueous extract was administered orally once daily at dose levels of 0, 125, 250, 500, 1000 and 2000 mg/kg/day for 13 weeks. Toxicological assessment was performed including mortality, clinical signs, body and organ weights, food consumption, ophthalmology, urinalysis, hematology, serum chemistry, gross findings and histopathologic examination. RESULTS: There were no treatment related differences in clinical signs, urinalysis, hematology and serum chemistry, except for a histopathologic examination. The squamous cell hyperplasia in the forestomach was observed in both sexes of rats given 2000 mg/kg/day of Leonuri Herba aqueous extract. CONCLUSION: In conclusion, the NOAEL (No Observed Adverse Effect Level) for Leonuri Herba aqueous extract was determined as 1000 mg/kg/day in both sexes of rats under the present experimental conditions. And the acceptable daily intake value for Leonuri Herba aqueous extract was calculated to be 10mg/kg body weight per day using a safety factor of 100 to the NOAEL.

In vitro and in vivo assessment of cytochrome P450-mediated herb-drug interaction of Ssang-hwa-tang.

We have evaluated the herb-drug interaction potential of Ssang-hwa-tang (SHT) mediated by cytochrome P450 (CYP) inhibition/induction. Further, the effects of fermentation on the CYP-mediated herb-drug interaction potential were determined. SHT showed inhibitory activity toward CYP1A2, but not 2A6, 2B6, 2C9, 2C19, 2D6, 2E1, and 3A4 in human liver microsomes. The results of the enzyme kinetic study suggested that the SHT-induced CYP1A2 inhibition is mixed reversible inhibition. The hepatic CYP expression and activity in rats treated with SHT were examined. The expression/activity of CYP2E1 increased as a result of SHT extract treatment (P<0.005 or P<0.001, respectively), which raises the possibility that SHT may increase the toxicity of environmental toxicants through the elevation of CYP2E1-mediated metabolic activation. SHT fermentation using Lactobacillus fermentum or Lactobacillus gasseri resulted in attenuation of the SHT-induced CYP1A2 inhibition, but not CYP2E1 induction, suggesting that changes in the chemical composition of SHT through fermentation can affect the inhibition of CYP1A2 activity.

Assessment of drug-drug interactions caused by metabolism-dependent cytochrome P450 inhibition.

This study was designed to develop methods for detecting metabolism-dependent reversible, quasi-irreversible, and irreversible cytochrome P450 (CYP) inhibition using pooled human liver microsomes and a liquid chromatography/tandem mass spectrometry (LC-MS/MS) system. Metabolism-dependent inhibition (MDI) was identified based on IC(50) shifts after pre-incubation of the tested compounds with NADPH. To distinguish reversible MDI from mechanism-based inhibition (MBI), R-fluoxetine and ticlopidine were used as positive inhibitors for reversible MDI and MBI of CYP2C19, respectively. R-fluoxetine and ticlopidine inhibited CYP2C19 activity, as determined using S-mephenytoin as a substrate, and caused 8.7- and 2.3-fold IC(50) shifts, respectively, after pre-incubation. Inhibition of CYP2C19 by R-fluoxetine, but not ticlopidine, was markedly reversed by ultracentrifugation, and two or three ultracentrifugations were not more effective than one, indicating that ultracentrifugation only once may be sufficient to reverse the reversible MDI. To distinguish between quasi-irreversible and irreversible inhibition, diltiazem and mifepristone were used as quasi-irreversible and irreversible inhibitors of CYP3A4, respectively, and CYP3A4 activity was measured using midazolam and testosterone as substrates. After pre-incubation, CYP3A4 IC(50) shifts caused by diltiazem and mifepristone were greater than 2.5- and 3.7-fold, respectively. Incubation with 2mM potassium ferricyanide for 10min reversed the MDI of CYP3A4 by diltiazem, but not mifepristone. Increases in potassium ferricyanide concentration and incubation time reduced the recovery of CYP3A4 activity. The established methods were confirmed using three CYP3A4 inhibitors including diltiazem, mifepristone and amiodarone (a reversible metabolism-dependent inhibitor). We consider these methods to be useful tools for discriminating between reversible MDI and MBI.

Assessment of reactive metabolites in drug-induced liver injury.

The aim of the current review is to summarize present methods used for the determination of reactive metabolites, which can predict drug-induced liver injury (DILI) in drug discovery and development. DILI is one of the most frequent reasons for the withdrawal of an approved drug from the market, and it accounts for up to 50% of acute liver failure cases. This review is structured into three sections. The first section is a general overview of the relationship between drug metabolism and liver injury. The second section introduces in vitro methods for the assessment of reactive metabolites for drug discovery and development. In the third section, limitations and future directions for the development of methods for predicting DILI are described.