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The DevTox Germ Layer Reporter Platform: An Assay Adaptation of the Human Pluripotent Stem Cell Test. TOXICS 2022; 10:toxics10070392. [PMID: 35878297 PMCID: PMC9321663 DOI: 10.3390/toxics10070392] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 06/14/2022] [Accepted: 06/30/2022] [Indexed: 11/16/2022]
Abstract
Environmental chemical exposures are a contributing factor to birth defects affecting infant morbidity and mortality. The USA EPA is committed to developing new approach methods (NAMs) to detect chemical risks to susceptible populations, including pregnant women. NAM-based coverage for cellular mechanisms associated with early human development could enhance identification of potential developmental toxicants (DevTox) for new and existing data-poor chemicals. The human pluripotent stem cell test (hPST) is an in vitro test method for rapidly identifying potential human developmental toxicants that employs directed differentiation of embryonic stem cells to measure reductions in SOX17 biomarker expression and nuclear localization. The objective of this study was to expand on the hPST principles to develop a model platform (DevTox GLR) that utilizes the transgenic RUES2-GLR cell line expressing fluorescent reporter fusion protein biomarkers for SOX17 (endoderm marker), BRA (mesoderm marker), and SOX2 (ectoderm and pluripotency marker). Initial assay adaption to definitive endoderm (DevTox GLR-Endo) was performed to emulate the hPST SOX17 endpoint and enable comparative evaluation of concordant chemical effects. Assay duration was reduced to two days and screening throughput scaled to 384-well format for enhanced speed and efficiency. Assay performance for 66 chemicals derived from reference and training set data resulted in a balanced accuracy of 72% (79% sensitivity and 65% specificity). The DevTox GLR-Endo assay demonstrates successful adaptation of the hPST concept with increased throughput, shorter assay duration, and minimal endpoint processing. The DevTox GLR model platform expands the in vitro NAM toolbox to rapidly identify potential developmental hazards and mechanistically characterize toxicant effects on pathways and processes associated with early human development.
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2
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Calabrese EJ. Hormesis and embryonic stem cells. Chem Biol Interact 2021; 352:109783. [PMID: 34932953 DOI: 10.1016/j.cbi.2021.109783] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 12/09/2021] [Accepted: 12/16/2021] [Indexed: 02/07/2023]
Abstract
This paper provides an identification and detailed assessment of hormetic dose responses of embryonic stem cells (ESCs) with particular emphasis on cell renewal (proliferation) and differentiation, underlying mechanistic foundations and potential therapeutic implications. Hormetic dose responses were commonly reported, being induced by a broad range of chemicals, including pharmaceuticals (e.g., atorvastatin, isoproterenol, lithium, nicotine, ouabain), dietary supplements (e.g., curcumin, multiple ginsenosides, resveratrol), endogenous agents (e.g., estrogen, hydrogen peroxide, melatonin), and physical stressor agents (e.g., hypoxia, ionizing radiation). ESC-hormetic dose responses are similar for other stem cell types (e.g., adipose-derived stem cells, apical papilla, bone marrow stem cells, dental pulp stem cells, endothelial stem cells, muscle stem cells, periodontal ligament stem cells, neural stem cells), indicating a high degree of generality for the hormetic-stem cells response. The widespread occurrence of hormetic dose responses shown by ESCs and other stem cells suggests that the hormetic dose response may represent a fundamental and highly conserved evolutionary strategy.
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Affiliation(s)
- Edward J Calabrese
- School of Public Health and Health Sciences, Department of Environmental Health Sciences, Morrill I, N344, University of Massachusetts, Amherst, MA, 01003, USA.
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Inselman A, Liu F, Wang C, Shi Q, Pang L, Mattes W, White M, Lyn-Cook B, Rosas-Hernandez H, Cuevas E, Lantz S, Imam S, Ali S, Petibone DM, Shemansky JM, Xiong R, Wang Y, Tripathi P, Cao X, Heflich RH, Slikker W. Dr. Daniel Acosta and In Vitro toxicology at the U.S. Food and Drug Administration's National Center for Toxicological Research. Toxicol In Vitro 2019; 64:104471. [PMID: 31628011 DOI: 10.1016/j.tiv.2019.03.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 03/01/2019] [Accepted: 03/04/2019] [Indexed: 10/25/2022]
Abstract
For the past five years, Dr. Daniel Acosta has served as the Deputy Director of Research at the National Center for Toxicological Research (NCTR), a principle research laboratory of the U.S. Food and Drug Administration (FDA). Over his career at NCTR, Dr. Acosta has had a major impact on developing and promoting the use of in vitro assays in regulatory toxicity and product safety assessments. As Dr. Acosta nears his retirement we have dedicated this paper to his many accomplishments at the NCTR. Described within this paper are some of the in vitro studies that have been conducted under Dr. Acosta's leadership. These studies include toxicological assessments involving developmental effects, and the development and application of in vitro reproductive, heart, liver, neurological and airway cell and tissue models.
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Affiliation(s)
- Amy Inselman
- Division of Systems Biology, NCTR, FDA, Jefferson, AR 72079, USA
| | - Fang Liu
- Division of Neurotoxicology, NCTR, FDA, Jefferson, AR 72079, USA
| | - Cheng Wang
- Division of Neurotoxicology, NCTR, FDA, Jefferson, AR 72079, USA
| | - Qiang Shi
- Division of Systems Biology, NCTR, FDA, Jefferson, AR 72079, USA
| | - Li Pang
- Division of Systems Biology, NCTR, FDA, Jefferson, AR 72079, USA
| | - William Mattes
- Division of Systems Biology, NCTR, FDA, Jefferson, AR 72079, USA
| | - Matthew White
- Arkansas College of Osteopathic Medicine, Fort Smith, AR 72916, USA
| | - Beverly Lyn-Cook
- Division of Biochemical Toxicology, NCTR, FDA, Jefferson, AR 72079, USA
| | | | - Elvis Cuevas
- Division of Neurotoxicology, NCTR, FDA, Jefferson, AR 72079, USA
| | - Susan Lantz
- Division of Neurotoxicology, NCTR, FDA, Jefferson, AR 72079, USA
| | - Syed Imam
- Division of Neurotoxicology, NCTR, FDA, Jefferson, AR 72079, USA
| | - Syed Ali
- Division of Neurotoxicology, NCTR, FDA, Jefferson, AR 72079, USA
| | - Dayton M Petibone
- Division of Genetic and Molecular Toxicology, NCTR, FDA, Jefferson, AR 72079, USA
| | - Jennifer M Shemansky
- Division of Genetic and Molecular Toxicology, NCTR, FDA, Jefferson, AR 72079, USA
| | - Rui Xiong
- Division of Genetic and Molecular Toxicology, NCTR, FDA, Jefferson, AR 72079, USA
| | - Yiying Wang
- Division of Genetic and Molecular Toxicology, NCTR, FDA, Jefferson, AR 72079, USA
| | - Priya Tripathi
- Division of Genetic and Molecular Toxicology, NCTR, FDA, Jefferson, AR 72079, USA
| | - Xuefei Cao
- Division of Genetic and Molecular Toxicology, NCTR, FDA, Jefferson, AR 72079, USA
| | - Robert H Heflich
- Division of Genetic and Molecular Toxicology, NCTR, FDA, Jefferson, AR 72079, USA
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Kim TW, Che JH, Yun JW. Use of stem cells as alternative methods to animal experimentation in predictive toxicology. Regul Toxicol Pharmacol 2019; 105:15-29. [DOI: 10.1016/j.yrtph.2019.03.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Revised: 03/23/2019] [Accepted: 03/25/2019] [Indexed: 12/16/2022]
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Abstract
Developmental toxicity associated with exposure to exogenous compounds such as drugs and environmental chemicals can be assessed using a variety of different in vitro models, each with their own advantages and disadvantages. These models include cultured cells (Chapters 3 - 6 ), organ and tissue cultures (Chapters 7 and 8 ), and whole embryo cultures (Chapters 13 - 15 ) and typically support the guiding principles of the three Rs: replace, reduce, and refine. These models can be used in early chemical screens and have helped further our understanding into the mechanisms associated with developmental toxicity following exposure to many chemicals.
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6
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Watt ED, Judson RS. Uncertainty quantification in ToxCast high throughput screening. PLoS One 2018; 13:e0196963. [PMID: 30044784 PMCID: PMC6059398 DOI: 10.1371/journal.pone.0196963] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 04/24/2018] [Indexed: 01/04/2023] Open
Abstract
High throughput screening (HTS) projects like the U.S. Environmental Protection Agency's ToxCast program are required to address the large and rapidly increasing number of chemicals for which we have little to no toxicity measurements. Concentration-response parameters such as potency and efficacy are extracted from HTS data using nonlinear regression, and models and analyses built from these parameters are used to predict in vivo and in vitro toxicity of thousands of chemicals. How these predictions are impacted by uncertainties that stem from parameter estimation and propagated through the models and analyses has not been well explored. While data size and complexity makes uncertainty quantification computationally expensive for HTS datasets, continued advancements in computational resources have allowed these computational challenges to be met. This study uses nonparametric bootstrap resampling to calculate uncertainties in concentration-response parameters from a variety of HTS assays. Using the ToxCast estrogen receptor model for bioactivity as a case study, we highlight how these uncertainties can be propagated through models to quantify the uncertainty in model outputs. Uncertainty quantification in model outputs is used to identify potential false positives and false negatives and to determine the distribution of model values around semi-arbitrary activity cutoffs, increasing confidence in model predictions. At the individual chemical-assay level, curves with high variability are flagged for manual inspection or retesting, focusing subject-matter-expert time on results that need further input. This work improves the confidence of predictions made using HTS data, increasing the ability to use this data in risk assessment.
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Affiliation(s)
- Eric D. Watt
- U.S. Environmental Protection Agency, National Center for Computational Toxicology, Research Triangle Park, North Carolina, United States of America
- Oak Ridge Institute for Science Education Postdoctoral Fellow, Oak Ridge, Tennessee, United States of America
| | - Richard S. Judson
- U.S. Environmental Protection Agency, National Center for Computational Toxicology, Research Triangle Park, North Carolina, United States of America
- * E-mail:
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Rosen MB, Jeffay SC, Nichols HP, Hoopes MR, Hunter ES. ATP Binding Cassette Sub-family Member 2 (ABCG2) and Xenobiotic Exposure During Early Mouse Embryonic Stem Cell Differentiation. Birth Defects Res 2018; 110:35-47. [PMID: 28990372 PMCID: PMC9831278 DOI: 10.1002/bdr2.1114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 07/25/2017] [Accepted: 07/28/2017] [Indexed: 01/13/2023]
Abstract
BACKGROUND ATP binding cassette sub-family member 2 (ABCG2) is a well-defined efflux transporter found in a variety of tissues. The role of ABCG2 during early embryonic development, however, is not established. Previous work which compared data from the ToxCast screening program with that from in-house studies suggested an association exists between exposure to xenobiotics that regulate Abcg2 transcription and differentiation of mouse embryonic stem cells (mESC), a relationship potentially related to redox homeostasis. METHODS mESC were grown for up to 9 days. Pharmacological inhibitors were used to assess transporter function with and without xenobiotic exposure. Proliferation and differentiation were evaluated using RedDot1 and quantiative reverse transcriptase-polymerase chain reaction, respectively. ABCG2 activity was assessed using a Pheophorbide a-based fluorescent assay. Protein expression was measured by capillary-based immunoassay. RESULTS ABCG2 activity increased in differentiating mESC. Treatment with K0143, an inhibitor of ABCG2, had no effect on proliferation or differentiation. As expected, mitoxantrone and topotecan, two chemotherapeutics, displayed increased toxicity in the presence of K0143. Exposure to K0143 in combination with chemicals predicted by ToxCast to regulate ABCG2 expression did not alter xenobiotic-induced toxicity. Moreover, inhibition of ABCG2 did not shift the toxicity of either tert-Butyl hydroperoxide or paraquat, two oxidative stressors. CONCLUSION As previously reported, ABCG2 serves a protective role in mESC. The role of ABCG2 in regulating redox status, however, was unclear. The hypothesis that ABCG2 plays a fundamental role during mESC differentiation or that regulation of the receptor by xenobiotics may be associated with altered mESC differentiation could not be supported. Birth Defects Research, 110:35-47, 2018. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.
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Affiliation(s)
- Mitchell B Rosen
- U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Integrated Systems Toxicology Division, Research Triangle Park, North Carolina
| | - Susan C Jeffay
- U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Integrated Systems Toxicology Division, Research Triangle Park, North Carolina
| | - Harriette P Nichols
- U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Integrated Systems Toxicology Division, Research Triangle Park, North Carolina
| | - Maria R Hoopes
- U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Integrated Systems Toxicology Division, Research Triangle Park, North Carolina
| | - E Sidney Hunter
- U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Integrated Systems Toxicology Division, Research Triangle Park, North Carolina
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Abstract
The development of stem cell biology has revolutionized regenerative medicine and its clinical applications. Another aspect through which stem cells would benefit human health is their use in toxicology. In fact, owing to their ability to differentiate into all the lineages of the human body, including germ cells, stem cells, and, in particular, pluripotent stem cells, can be utilized for the assessment, in vitro, of embryonic, developmental, reproductive, organ, and functional toxicities, relevant to human physiology, without employing live animal tests and with the possibility of high throughput applications. Thus, stem cell toxicology would tremendously assist in the toxicological evaluation of the increasing number of synthetic chemicals that we are exposed to, of which toxicity information is limited. In this review, we introduce stem cell toxicology, as an emerging branch of in vitro toxicology, which offers quick and efficient alternatives to traditional toxicology assessments. We first discuss the development of stem cell toxicology, and we then emphasize its advantages and highlight the achievements of human pluripotent stem cell-based toxicity research.
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Affiliation(s)
- Shuyu Liu
- 1 State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences , Chinese Academy of Sciences, Beijing, P.R. China .,2 College of Resources and Environment, University of Chinese Academy of Sciences , Beijing, P.R. China
| | - Nuoya Yin
- 1 State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences , Chinese Academy of Sciences, Beijing, P.R. China .,2 College of Resources and Environment, University of Chinese Academy of Sciences , Beijing, P.R. China
| | - Francesco Faiola
- 1 State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences , Chinese Academy of Sciences, Beijing, P.R. China .,2 College of Resources and Environment, University of Chinese Academy of Sciences , Beijing, P.R. China
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Brannen KC, Chapin RE, Jacobs AC, Green ML. Alternative Models of Developmental and Reproductive Toxicity in Pharmaceutical Risk Assessment and the 3Rs. ILAR J 2017; 57:144-156. [DOI: 10.1093/ilar/ilw026] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2016] [Revised: 01/01/2016] [Accepted: 01/01/2016] [Indexed: 01/21/2023] Open
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10
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Yao X, Yin N, Faiola F. Stem cell toxicology: a powerful tool to assess pollution effects on human health. Natl Sci Rev 2016. [DOI: 10.1093/nsr/nww089] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
AbstractEnvironmental pollution is a global problem; the lack of comprehensive toxicological assessments may lead to increased health risks. To fully understand the health effects of pollution, it is paramount to implement fast, efficient and specific toxicity screening that relies on human models rather than on time-consuming, expensive and often inaccurate tests involving live animals. Human stem cell toxicology represents a valid alternative to traditional toxicity assays because it takes advantage of the ability of stem cells to differentiate into multiple cell types and tissues of the human body. Thus, this branch of toxicology provides a possibility to assess cellular, embryonic, developmental, reproductive and functional toxicity in vitro within a single system highly relevant to human physiology. In this review, we describe the development, performance and future perspectives of stem cell toxicology, with an emphasis on how it can meet the increasing challenges posed by environmental pollution in the modern world.
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Affiliation(s)
- Xinglei Yao
- Stake Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Nuoya Yin
- Stake Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Francesco Faiola
- Stake Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
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11
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Cheng W, Zhou R, Liang F, Wei H, Feng Y, Wang Y. Application of Mouse Embryonic Stem Cell Test to Detect Gender-Specific Effect of Chemicals: A Supplementary Tool for Embryotoxicity Prediction. Chem Res Toxicol 2016; 29:1519-33. [PMID: 27445234 DOI: 10.1021/acs.chemrestox.6b00197] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Gender effect is an inherent property of chemicals, characterized by variations caused by the chemical-biology interaction. It has widely existed, but the shortage of an appropriate model restricts the study on gender-specific effect. The embryonic stem cell test (EST) has been utilized as an alternative test for developmental toxicity. Despite its numerous improvements, mouse embryonic stem cells with an XX karyotype have not been used in the EST, which restricts the ability of the EST to identify gender-specific effects during high-throughput-screening (HTS) of chemicals to date. To address this, the embryonic stem cell (ESC) SP3 line with an XX karyotype was used to establish a "female" model as a complement to EST. Here, we proposed a "double-objects in unison" (DOU)-EST, which consisted of male ESC and female ESC; a seven-day EST protocol was utilized, and the gender-specific effect of chemicals was determined and discriminated; the replacement of myosin heavy chain (MHC) with myosin light chain (MLC) provided a suitable molecular biomarker in the DOU-EST. New linear discriminant functions were given in the purpose of distinguishing chemicals into three classes, namely, no gender-specific effect, male-susceptive, and female-susceptive. For 15 chemicals in the training set, the concordances of prediction result as no gender effect, male susceptive, and female susceptive were 86.67%, 86.67%, and 93.33%, respectively, the sensitivities were 66.67%, 83.33%, and 83.33%, respectively, and the specificities were 91.67%, 88.89%, and 100%, respectively; the total accuracy of DOU-EST was 86.67%. For three chemicals in the test set, one was incorrectively predicted. The possible reason for misclassification may due to the absence of hormone environment in vitro. Leave-one-out cross-validation (LOOCV) indicated a mean error rate of 18.34%. Taken together, these data suggested a good performance of the proposed DOU-EST. Emerging chemicals with undiscovered gender-specific effects are anticipated to be screened with the DOU-EST.
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Affiliation(s)
- Wei Cheng
- College of Public Health, School of Medicine, Shanghai Jiaotong University , Shanghai 200025, P.R. China
| | - Ren Zhou
- College of Public Health, School of Medicine, Shanghai Jiaotong University , Shanghai 200025, P.R. China
| | - Fan Liang
- College of Public Health, School of Medicine, Shanghai Jiaotong University , Shanghai 200025, P.R. China
| | - Hongying Wei
- College of Public Health, School of Medicine, Shanghai Jiaotong University , Shanghai 200025, P.R. China.,Hongqiao International Institute of Medicine, School of Medicine, Shanghai Jiaotong University , Shanghai 200336, P.R. China
| | - Yan Feng
- College of Public Health, School of Medicine, Shanghai Jiaotong University , Shanghai 200025, P.R. China
| | - Yan Wang
- College of Public Health, School of Medicine, Shanghai Jiaotong University , Shanghai 200025, P.R. China.,Hongqiao International Institute of Medicine, School of Medicine, Shanghai Jiaotong University , Shanghai 200336, P.R. China.,Shanghai Ninth People's Hospital Affiliated to Shanghai Jiaotong University School of Medicine , Shanghai 200011, P.R. China
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Zhang C, Ball J, Panzica-Kelly J, Augustine-Rauch K. In Vitro Developmental Toxicology Screens: A Report on the Progress of the Methodology and Future Applications. Chem Res Toxicol 2016; 29:534-44. [DOI: 10.1021/acs.chemrestox.5b00458] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Cindy Zhang
- Discovery
Toxicology, Bristol Myers Squibb, Pennington, New Jersey 08534, United States
| | - Jonathan Ball
- College
of Life and Environmental Sciences, University of Exeter, Exeter EX4 4PS, United Kingdom
| | - Julie Panzica-Kelly
- Discovery
Toxicology, Bristol Myers Squibb, Pennington, New Jersey 08534, United States
| | - Karen Augustine-Rauch
- Discovery
Toxicology, Bristol Myers Squibb, Pennington, New Jersey 08534, United States
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13
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Augustine-Rauch K, Zhang CX, Panzica-Kelly JM. A Developmental Toxicology Assay Platform for Screening Teratogenic Liability of Pharmaceutical Compounds. ACTA ACUST UNITED AC 2016; 107:4-20. [PMID: 26729651 DOI: 10.1002/bdrb.21168] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 11/18/2015] [Indexed: 01/14/2023]
Abstract
Increasing need for proactive safety optimization of pharmaceutical compounds has led to generation and/or refinement of in vitro developmental toxicology assays. Our laboratory has developed three in vitro developmental toxicology assays to assess teratogenic liability of pharmaceutical compounds. These assays included a mouse molecular embryonic stem cell assay (MESCA), a dechorionated zebrafish embryo culture (ZEC) assay, and a streamlined rat whole embryo culture (rWEC) assay. Individually, the assays presented good (73-82%) predictivity. However, it remains to be determined whether combining or tiering the assays could enhance performance. Seventy-three compounds representing a broad spectrum of pharmaceutical targets and chemistry were evaluated across the assays to generate testing strategies that optimized performance. The MESCA and ZEC assays were found to have two limitations: compound solubility and frequent misclassification of compounds with H1 receptor or GABAnergic activity. The streamlined rWEC assay was found to be a cost-effective stand-alone assay for supporting poorly soluble compounds and/or ones with H1 or GABAnergic activity. For all other compounds, a tiering strategy using the MESCA and ZEC assays additionally optimized throughput, cost, and minimized animal use. The tiered strategy resulted in improved performance achieving 88% overall predictivity and was comparable with 89% overall predictivity achieved with frequency analysis (final teratogenic classification made from most frequent teratogenic classification from each individual assay). Furthermore there were 21 compounds in the test set characterized as definitive or suspect human teratogens and the multiassay approach achieved 95 and 91% correct classification using the tiered or frequency screening approach, respectively.
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Affiliation(s)
| | - Cindy X Zhang
- Discovery Toxicology Group, Bristol Myers-Squibb, Hopewell, New Jersey
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14
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Use of alternative assays to identify and prioritize organophosphorus flame retardants for potential developmental and neurotoxicity. Neurotoxicol Teratol 2015; 52:181-93. [DOI: 10.1016/j.ntt.2015.09.003] [Citation(s) in RCA: 129] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 09/02/2015] [Accepted: 09/02/2015] [Indexed: 12/26/2022]
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15
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An integrated approach for detecting embryotoxicity and developmental toxicity of environmental contaminants using in vitro alternative methods. Toxicol Lett 2014; 230:356-67. [DOI: 10.1016/j.toxlet.2014.01.037] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2013] [Revised: 12/10/2013] [Accepted: 01/27/2014] [Indexed: 11/19/2022]
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Abstract
Understanding the potential health risks posed by environmental chemicals is a significant challenge elevated by the large number of diverse chemicals with generally uncharacterized exposures, mechanisms, and toxicities. The ToxCast computational toxicology research program was launched by EPA in 2007 and is part of the federal Tox21 consortium to develop a cost-effective approach for efficiently prioritizing the toxicity testing of thousands of chemicals and the application of this information to assessing human toxicology. ToxCast addresses this problem through an integrated workflow using high-throughput screening (HTS) of chemical libraries across more than 650 in vitro assays including biochemical assays, human cells and cell lines, and alternative models such as mouse embryonic stem cells and zebrafish embryo development. The initial phase of ToxCast profiled a library of 309 environmental chemicals, mostly pesticidal actives having rich in vivo data from guideline studies that include chronic/cancer bioassays in mice and rats, multigenerational reproductive studies in rats, and prenatal developmental toxicity endpoints in rats and rabbits. The first phase of ToxCast was used to build models that aim to determine how well in vivo animal effects can be predicted solely from the in vitro data. Phase I is now complete and both the in vitro data (ToxCast) and anchoring in vivo database (ToxRefDB) have been made available to the public (http://actor.epa.gov/). As Phase II of ToxCast is now underway, the purpose of this chapter is to review progress to date with ToxCast predictive modeling, using specific examples on developmental and reproductive effects in rats and rabbits with lessons learned during Phase I.
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Panzica-Kelly JM, Brannen KC, Ma Y, Zhang CX, Flint OP, Lehman-McKeeman LD, Augustine-Rauch KA. Establishment of a molecular embryonic stem cell developmental toxicity assay. Toxicol Sci 2012; 131:447-57. [PMID: 23042729 DOI: 10.1093/toxsci/kfs293] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The mouse embryonic stem cell test (EST) is a 10-day screen for teratogenic potential developed to reduce animal use for embryotoxicity testing of chemicals (Spielmann, 2005; Spielmann et al., 1997). In this study, we used the cytotoxicity IC(50) values and transcriptional expression changes as primary endpoints in a shorter 4-day version of the EST, the molecular embryonic stem cell assay. Mouse D3 embryonic stem cells were used for cytotoxicity assessment (monolayers) or grown as embryoid bodies in low attachment plates for transcriptional profiling. Sixty-five compounds with known in vivo teratogenicity (33 teratogens and 32 nonteratogens) were evaluated to develop a model for classifying compounds with teratogenic potential. The expression of 12 developmentally regulated gene targets (nanog, fgf5, gsc, cd34, axin2, apln, chst7, lhx1, fgf8, sox17, foxa2, and cxcr4) was measured following exposure of embryoid bodies to a single compound concentration (0.1 × the cytotoxicity IC(20)) for 4 days. In the decision-tree model, compounds with IC(50) values < 22 µM were categorized as teratogens, whereas compounds in the two groups with IC(50) values between 22-200 µM and > 200 µM were categorized as teratogens if ≥ 8 and 12 genes, respectively, were deregulated by at least 10%. Forty-seven of 65 compounds of the training set were correctly identified (72% total concordance). In a test set of 12 additional compounds (5 teratogens, 7 nonteratogens), 10 were correctly classified by this approach (83% concordance). The false positive rate in the training and test sets was 24 and 0%, respectively, indicating that this assay has potential to identify teratogens.
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Abstract
There are thousands of environmental chemicals for which there is limited toxicological information, motivating the development and application of in vitro systems to profile the biological effects of xenobiotic exposure and predict their potential developmental hazard. An adherent cell differentiation and cytotoxicity (ACDC) assay was developed using pluripotent mouse embryonic stem cells (mESCs) to evaluate chemical-induced effects on both stem cell viability and differentiation. This assay uses an In-Cell Western technique after a 9-day culture. DRAQ5/Sapphire700 cell/DNA stains are used to quantify cell number and myosin heavy chain (MHC) protein is used as a marker of cardiomyocyte differentiation. MHC is corrected for cell number, thereby separating cytotoxicity and effects on differentiation. The ACDC assay can be used to evaluate the effects of xenobiotics on mESC differentiation and cell number in the same sample.
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Abstract
In light of various pressures, toxicologists have been searching for alternative methods for safety testing of chemicals. According to a recent policy in the European Union (Regulation, Evaluation Authorisation and Restriction of Chemicals, REACH), it has been estimated that over the next twelve to fifteen years, approximately 30,000 chemicals may need to be tested for safety, and under current guidelines such testing would require the use of approximately 7.2 million laboratory animals [ Hofer et al. 2004 ]. It has also been estimated that over 80% of all animals used for safety testing under REACH legislation would be used for examining reproductive and developmental toxicity [Hofer et al., 2004]. In addition to REACH initiatives, it has been estimated that out of 5,000 to 10,000 new drug entities that a pharmaceutical company may start with, only one is finally approved by the Food and Drug Administration at a cost of over one billion dollars [ Garg et al. 2011 ]. A large portion of this cost is due to animal testing. Therefore, both the pharmaceutical and chemical industries are interested in using alternative models and in vitro tests for safety testing. This review will examine the current state of three alternative models - whole embryo culture (WEC), the mouse embryonic stem cell test (mEST), and zebrafish. Each of these alternatives will be reviewed, and advantages and disadvantages of each model will be discussed. These models were chosen because they are the models most commonly used and would appear to have the greatest potential for future applications in developmental toxicity screening and testing.
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Affiliation(s)
- Hyung-yul Lee
- Division of Personalized Nutrition and Medicine, FDA/National Center for Toxicological Research, Jefferson, AR 72079, USA
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Kavlock R, Chandler K, Houck K, Hunter S, Judson R, Kleinstreuer N, Knudsen T, Martin M, Padilla S, Reif D, Richard A, Rotroff D, Sipes N, Dix D. Update on EPA's ToxCast program: providing high throughput decision support tools for chemical risk management. Chem Res Toxicol 2012; 25:1287-302. [PMID: 22519603 DOI: 10.1021/tx3000939] [Citation(s) in RCA: 327] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The field of toxicology is on the cusp of a major transformation in how the safety and hazard of chemicals are evaluated for potential effects on human health and the environment. Brought on by the recognition of the limitations of the current paradigm in terms of cost, time, and throughput, combined with the ever increasing power of modern biological tools to probe mechanisms of chemical-biological interactions at finer and finer resolutions, 21st century toxicology is rapidly taking shape. A key element of the new approach is a focus on the molecular and cellular pathways that are the targets of chemical interactions. By understanding toxicity in this manner, we begin to learn how chemicals cause toxicity, as opposed to merely what diseases or health effects they might cause. This deeper understanding leads to increasing confidence in identifying which populations might be at risk, significant susceptibility factors, and key influences on the shape of the dose-response curve. The U. S. Environmental Protection Agency (EPA) initiated the ToxCast, or "toxicity forecaster", program 5 years ago to gain understanding of the strengths and limitations of the new approach by starting to test relatively large numbers (hundreds) of chemicals against an equally large number of biological assays. Using computational approaches, the EPA is building decision support tools based on ToxCast in vitro screening results to help prioritize chemicals for further investigation, as well as developing predictive models for a number of health outcomes. This perspective provides a summary of the initial, proof of concept, Phase I of ToxCast that has laid the groundwork for the next phases and future directions of the program.
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Affiliation(s)
- Robert Kavlock
- National Center for Computational Toxicology, Office of Research and Development, U. S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
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Theunissen PT, Robinson JF, Pennings JLA, de Jong E, Claessen SMH, Kleinjans JCS, Piersma AH. Transcriptomic concentration-response evaluation of valproic acid, cyproconazole, and hexaconazole in the neural embryonic stem cell test (ESTn). Toxicol Sci 2011; 125:430-8. [PMID: 22045034 DOI: 10.1093/toxsci/kfr293] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Alternative developmental toxicity assays are urgently needed to reduce animal use in regulatory developmental toxicology. We previously designed an in vitro murine neural embryonic stem cell test (ESTn) as a model for neurodevelopmental toxicity testing (Theunissen et al., 2010). Toxicogenomic approaches have been suggested for incorporation into the ESTn to further increase predictivity and to provide mechanistic insights. Therefore, in this study, using a transcriptomic approach, we investigated the concentration-dependent effects of three known (neuro) developmental toxicants, two triazoles, cyproconazole (CYP) and hexaconazole (HEX), and the anticonvulsant valproic acid (VPA). Compound effects on gene expression during neural differentiation and corresponding regulated gene ontology (GO) terms were identified after 24 h of exposure in relation to morphological changes on day 11 of culture. Concentration-dependent responses on individual gene expression and on biological processes were determined for each compound, providing information on mechanism and concentration-response characteristics. All compounds caused enrichment of the embryonic development process. CYP and VPA but not HEX significantly enriched the neuron development process. Furthermore, specific responses for triazole compounds and VPA were observed within the GO-term sterol metabolic process. The incorporation of transcriptomics in the ESTn was shown to enable detection of effects, which precede morphological changes and provide a more sensitive measure of concentration-dependent effects as compared with classical morphological assessments. Furthermore, mechanistic insight can be instrumental in the extrapolation of effects in the ESTn to human hazard assessment.
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Affiliation(s)
- Peter T Theunissen
- Laboratory for Health Protection Research, National Institute for Public Health and the Environment (RIVM), 3720 BA Bilthoven, The Netherlands.
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22
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Identifying developmental toxicity pathways for a subset of ToxCast chemicals using human embryonic stem cells and metabolomics. Toxicol Appl Pharmacol 2011; 257:111-21. [PMID: 21925528 DOI: 10.1016/j.taap.2011.08.025] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 08/28/2011] [Indexed: 11/23/2022]
Abstract
Metabolomics analysis was performed on the supernatant of human embryonic stem (hES) cell cultures exposed to a blinded subset of 11 chemicals selected from the chemical library of EPA's ToxCast™ chemical screening and prioritization research project. Metabolites from hES cultures were evaluated for known and novel signatures that may be indicative of developmental toxicity. Significant fold changes in endogenous metabolites were detected for 83 putatively annotated mass features in response to the subset of ToxCast chemicals. The annotations were mapped to specific human metabolic pathways. This revealed strong effects on pathways for nicotinate and nicotinamide metabolism, pantothenate and CoA biosynthesis, glutathione metabolism, and arginine and proline metabolism pathways. Predictivity for adverse outcomes in mammalian prenatal developmental toxicity studies used ToxRefDB and other sources of information, including Stemina Biomarker Discovery's predictive DevTox® model trained on 23 pharmaceutical agents of known developmental toxicity and differing potency. The model initially predicted developmental toxicity from the blinded ToxCast compounds in concordance with animal data with 73% accuracy. Retraining the model with data from the unblinded test compounds at one concentration level increased the predictive accuracy for the remaining concentrations to 83%. These preliminary results on a 11-chemical subset of the ToxCast chemical library indicate that metabolomics analysis of the hES secretome provides information valuable for predictive modeling and mechanistic understanding of mammalian developmental toxicity.
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