1
|
Sanz-Serrano J, Garayoa R, Vitas AI, López de Cerain A, Azqueta A. In vitro genotoxicity assessment of French fries from mass catering companies: a preliminary study. Mutagenesis 2022; 38:51-57. [PMID: 36242551 PMCID: PMC9897018 DOI: 10.1093/mutage/geac021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 10/02/2022] [Indexed: 02/07/2023] Open
Abstract
It is generally assumed that French fries are likely to have weak in vitro mutagenic activity, but most studies thereof have only assessed gene mutations. In this article, the genotoxicity of 10 extracts of French fries was assessed using the in vitro micronucleus test (following the principles of the OECD 487 guidelines). Each sample was obtained from a different mass catering company in Navarra (Spain). This assay, together with the Ames test, is recommended in the basic in vitro phase included in the European Food Safety Authority Opinion on Genotoxicity Testing Strategies Applicable to Food and Feed Safety Assessment. Eight of 10 samples from mass catering companies induced chromosomal aberrations in the in vitro micronucleus test. Moreover, French fries deep-fried in the laboratory for different periods of time (0, 3, 5, 10, 20, 30 min) were assessed using the in vitro micronucleus test. Genotoxicity was observed in all time periods from 3 min on. The biological relevance of these results must be further explored.
Collapse
Affiliation(s)
- Julen Sanz-Serrano
- Corresponding author. Department of Pharmacology and Toxicology, School of Pharmacy and Nutrition, Universidad de Navarra, Irunlarrea 1, 31008 Pamplona, Spain. E-mail:
| | - Roncesvalles Garayoa
- Department of Nutrition, Food Science and Physiology, Universidad de Navarra, School of Pharmacy and Nutrition, Irunlarrea 1, 31008 Pamplona, Spain
| | - Ana Isabel Vitas
- IdiSNA, Navarra Institute for Health Research, Irunlarrea 3, 31008, Pamplona, Spain,Department of Microbiology and Parasitology, School of Medicine, Universidad de Navarra, Irunlarrea 1, 31008, Pamplona, Spain
| | - Adela López de Cerain
- Department of Pharmacology and Toxicology, School of Pharmacy and Nutrition, Universidad de Navarra, Irunlarrea 1, 31008 Pamplona, Spain,IdiSNA, Navarra Institute for Health Research, Irunlarrea 3, 31008, Pamplona, Spain
| | - Amaya Azqueta
- Department of Pharmacology and Toxicology, School of Pharmacy and Nutrition, Universidad de Navarra, Irunlarrea 1, 31008 Pamplona, Spain,IdiSNA, Navarra Institute for Health Research, Irunlarrea 3, 31008, Pamplona, Spain
| |
Collapse
|
2
|
Thorne D, Whitwell J, Clements J, Walker P, Breheny D, Gaca M. The genotoxicological assessment of a tobacco heating product relative to cigarette smoke using the in vitro micronucleus assay. Toxicol Rep 2020; 7:1010-1019. [PMID: 32874925 PMCID: PMC7451629 DOI: 10.1016/j.toxrep.2020.08.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 08/03/2020] [Accepted: 08/10/2020] [Indexed: 01/02/2023] Open
Abstract
In vitro studies have supported the toxicological evaluation of chemicals and complex mixtures including cigarette smoke and novel tobacco and nicotine products which include tobacco heating products (THP). This new environment requires faster testing, higher throughput and appropriate in vitro studies, to support product innovation and development. In this study, total particulate matter (TPM) from a commercially available THP and a reference cigarette (3R4F) were assessed up to 500 μg/mL using two in vitro micronucleus techniques. V79 and TK6 cells were assessed using conventional OECD 487 manual scoring techniques, whereas, CHO cells were assessed using contemporary, automated high content screening approaches (Cellomics ArrayScan® VTI). V79 cells gave the most consistent response with all three treatment conditions producing a clear positive genotoxic response. Human TK6 cells only produced dose-dependent response, indicative of a weak-positive response. CHO cells demonstrated a positive response with TPM using long (24 h) -S9 conditions. All three cell lines equally demonstrated a negative response with THP TPM up to 500 μg/mL. In conclusion, THP TPM did not increase micronuclei formation above control levels even at doses far exceeding that tested with reference cigarette smoke, in most cases up to 10x the dose delivered compared to that of cigarette smoke. This study supports the growing belief that THPs are less risky than conventional cigarettes and that 21st century screening techniques can be employed to support product design and decision making, as a potential 1st screen prior to more traditional assessments.
Collapse
Key Words
- 3R4F, Research reference cigarette
- CHO
- CRM, 81 CORESTA recommended method 81
- DMSO, dimethyl sulphoxide
- E-cigarette, electronic cigarette
- HCI, Health Canada Intense smoking regimen
- HCIm, Health Canada Intense modified smoking regimen
- High content screening
- ISO, International Standards Organisation
- IVMN
- IVMN, in vitro micronucleus assay
- In vitro
- NGP, Next generation products
- S9, mammalian liver post-mitochondrial fraction
- THP, tobacco heating product
- TK6
- TPM, total particulate matter
- Tobacco heating product
- V79
Collapse
Affiliation(s)
- David Thorne
- British American Tobacco, R&D, Southampton, Hampshire, SO15 8TL, UK
| | - James Whitwell
- Covance Laboratories Ltd., Otley Road, Harrogate, North Yorkshire HG3 1PY, UK
| | - Julie Clements
- Covance Laboratories Ltd., Otley Road, Harrogate, North Yorkshire HG3 1PY, UK
| | - Paul Walker
- Cyprotex Discovery, Alderley Park, Alderley, Cheshire, SK10 4TG, UK
| | - Damien Breheny
- British American Tobacco, R&D, Southampton, Hampshire, SO15 8TL, UK
| | - Marianna Gaca
- British American Tobacco, R&D, Southampton, Hampshire, SO15 8TL, UK
| |
Collapse
|
3
|
Elevated H2AX Phosphorylation Observed with kINPen Plasma Treatment Is Not Caused by ROS-Mediated DNA Damage but Is the Consequence of Apoptosis. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2019; 2019:8535163. [PMID: 31641425 PMCID: PMC6770374 DOI: 10.1155/2019/8535163] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 07/23/2019] [Accepted: 08/26/2019] [Indexed: 12/11/2022]
Abstract
Phosphorylated histone 2AX (γH2AX) is a long-standing marker for DNA double-strand breaks (DSBs) from ionizing radiation in the field of radiobiology. This led to the perception of γH2AX being a general marker of direct DNA damage with the treatment of other agents such as low-dose exogenous ROS that unlikely act on cellular DNA directly. Cold physical plasma confers biomedical effects majorly via release of reactive oxygen and nitrogen species (ROS). In vitro, increase of γH2AX has often been observed with plasma treatment, leading to the conclusion that DNA damage is a direct consequence of plasma exposure. However, increase in γH2AX also occurs during apoptosis, which is often observed with plasma treatment as well. Moreover, it must be questioned if plasma-derived ROS can reach into the nucleus and still be reactive enough to damage DNA directly. We investigated γH2AX induction in a lymphocyte cell line upon ROS exposure (plasma, hydrogen peroxide, or hypochlorous acid) or UV-B light. Cytotoxicity and γH2AX induction was abrogated by the use of antioxidants with all types of ROS treatment but not UV radiation. H2AX phosphorylation levels were overall independent of analyzing either all nucleated cells or segmenting γH2AX phosphorylation for each cell cycle phase. SB202190 (p38-MAPK inhibitor) and Z-VAD-FMK (pan-caspase inhibitor) significantly inhibited γH2AX induction upon ROS but not UV treatment. Finally, and despite γH2AX induction, UV but not plasma treatment led to significantly increased micronucleus formation, which is a functional read-out of genotoxic DNA DSBs. We conclude that plasma-mediated and low-ROS γH2AX induction depends on caspase activation and hence is not the cause but consequence of apoptosis induction. Moreover, we could not identify lasting mutagenic effects with plasma treatment despite phosphorylation of H2AX.
Collapse
|
4
|
Micronucleus Analysis by Flow Cytometry. Methods Mol Biol 2019. [PMID: 31473960 DOI: 10.1007/978-1-4939-9646-9_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
During the last two decades the micronucleus (MN) test has been extensively used as a genotoxicity screening tool of chemicals and in a variety of exploratory and mechanistic investigations. The MN is a biomarker for chromosomal damage or mitotic abnormalities since it can originate from chromosome fragments or whole chromosomes that fail to be incorporated into daughter nuclei during mitosis (Fenech et al., Mutagenesis 26: 125-132, 2011; Kirsch-Volders et al., Arch Toxicol 85: 873-899, 2011). The simplicity of scoring, accuracy, amenability to automation by image analysis or flow cytometry and the readiness to be applied to a variety of cell types either in vitro or in vivo made it a versatile tool that contributed to a large extent in our understanding of key toxicological issues related to genotoxins and their effects at the cellular and organism levels. Recently, the final acceptance of the in vitro MN test Organization for Economic Cooperation and Development (OECD) guideline 487 (OECD, Guideline for testing of chemicals: in vitro mammalian cell micronucleus test 487: in vitro mammalian cell micronucleus test (MNVIT). Organization for Economic Cooperation and Development, Paris, 2010) together with the standard in vivo MN test OECD guideline 474 (OECD, Guideline for the testing of chemicals no. 474 mammalian erythrocyte micronucleus test. Organization for Economic Cooperation and Development, Paris, 1997) further positioned the assay as a key driver in the determination of the genotoxicity potential in exploratory research as well as in the regulatory environment. This book chapter covers to some extent the protocol designs and experimental steps necessary for a successful performance of the MN test and an accurate analysis of the MN by the flow cytometry technique.
Collapse
|
5
|
Rodrigues MA. Automation of the in vitro micronucleus assay using the Imagestream ® imaging flow cytometer. Cytometry A 2018; 93:706-726. [PMID: 30118149 PMCID: PMC6174940 DOI: 10.1002/cyto.a.23493] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 04/16/2018] [Accepted: 04/25/2018] [Indexed: 12/02/2022]
Abstract
The in vitro micronucleus (MN) assay is a well‐established test for evaluating genotoxicity and cytotoxicity. The use of manual microscopy to perform the assay can be laborious and often suffers from user subjectivity and interscorer variability. Automated methods including slide‐scanning microscopy and conventional flow cytometry have been developed to eliminate scorer bias and improve throughput. However, these methods possess several limitations such as lack of cytoplasmic visualization using slide‐scanning microscopy and the inability to visually confirm the legitimacy of MN or storage of image data for re‐evaluation using flow cytometry. The ImageStreamX® MK II (ISX) imaging flow cytometer has been demonstrated to overcome all of these limitations. The ISX combines the speed, statistical robustness, and rare event capture capability of conventional flow cytometry with high resolution fluorescent imagery of microscopy and possesses the ability to store all collected image data. This paper details the methodology developed to perform the in vitro MN assay in human lymphoblastoid TK6 cells on the ISX. High resolution images of micronucleated mono‐ and bi‐nucleated cells as well as polynucleated cells can be acquired at a high rate of capture. All images can then be automatically identified, categorized and enumerated in the data analysis software that accompanies the ImageStream, allowing for the scoring of both genotoxicity and cytotoxicity. The results demonstrate that statistically significant increases in MN frequency when compared with solvent controls can be detected at varying levels of cytotoxicity following exposure to well‐known aneugens and clastogens. This work demonstrates a fully automated method for performing the in vitro micronucleus assay on the ISX imaging flow cytometry platform. © 2018 The Author. Cytometry Part A published by Wiley Periodicals, Inc. on behalf of ISAC.
Collapse
|
6
|
Bekeschus S, Schmidt A, Kramer A, Metelmann HR, Adler F, von Woedtke T, Niessner F, Weltmann KD, Wende K. High throughput image cytometry micronucleus assay to investigate the presence or absence of mutagenic effects of cold physical plasma. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2018; 59:268-277. [PMID: 29417643 DOI: 10.1002/em.22172] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 11/17/2017] [Accepted: 11/21/2017] [Indexed: 06/08/2023]
Abstract
Promising cold physical plasma sources have been developed in the field of plasma medicine. An important prerequisite to their clinical use is lack of genotoxic effects in cells. During optimization of one or even different plasma sources for a specific application, large numbers of samples need to be analyzed. There are soft and easy-to-assess markers for genotoxic stress such as phosphorylation of histone H2AX (γH2AX) but only few tests are accredited by the OECD with regard to mutagenicity detection. The micronucleus (MN) assay is among them but often requires manual counting of many thousands of cells per sample under the microscope. A high-throughput MN assay is presented using image flow cytometry and image analysis software. A human lymphocyte cell line was treated with plasma generated with ten different feed gas conditions corresponding to distinct reactive species patterns that were investigated for their genotoxic potential. Several millions of cells were automatically analyzed by a MN quantification strategy outlined in detail in this work. Our data demonstrates the absence of newly formed MN in any feed gas condition using the atmospheric pressure plasma jet kINPen. As positive control, ionizing radiation gave a significant 5-fold increase in micronucleus frequency. Thus, this assay is suitable to assess the genotoxic potential in large sample sets of cells exposed chemical or physical agents including plasmas in an efficient, reliable, and semiautomated manner. Environ. Mol. Mutagen. 59:268-277, 2018. © 2018 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Sander Bekeschus
- ZIK plasmatis, Leibniz-Institute for Plasma Science and Technology (INP Greifswald), Greifswald, Germany
| | - Anke Schmidt
- ZIK plasmatis, Leibniz-Institute for Plasma Science and Technology (INP Greifswald), Greifswald, Germany
| | - Axel Kramer
- Institute for Hygiene and Environmental Medicine, University Medicine Greifswald, Greifswald, Germany
| | - Hans-Robert Metelmann
- Department of Oral and Maxillofacial Surgery/Plastic Surgery, University Medicine Greifswald, Greifswald, Germany
| | - Frank Adler
- Department of Radiotherapy, University Medicine Greifswald, Greifswald, Germany
| | - Thomas von Woedtke
- ZIK plasmatis, Leibniz-Institute for Plasma Science and Technology (INP Greifswald), Greifswald, Germany
- Institute for Hygiene and Environmental Medicine, University Medicine Greifswald, Greifswald, Germany
| | - Felix Niessner
- ZIK plasmatis, Leibniz-Institute for Plasma Science and Technology (INP Greifswald), Greifswald, Germany
| | - Klaus-Dieter Weltmann
- ZIK plasmatis, Leibniz-Institute for Plasma Science and Technology (INP Greifswald), Greifswald, Germany
| | - Kristian Wende
- ZIK plasmatis, Leibniz-Institute for Plasma Science and Technology (INP Greifswald), Greifswald, Germany
| |
Collapse
|
7
|
Genotoxicity evaluation of multi-component mixtures of polyaromatic hydrocarbons (PAHs), arsenic, cadmium, and lead using flow cytometry based micronucleus test in HepG2 cells. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2018; 827:9-18. [DOI: 10.1016/j.mrgentox.2018.01.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 12/16/2017] [Accepted: 01/09/2018] [Indexed: 01/09/2023]
|
8
|
Le Bihanic F, Di Bucchianico S, Karlsson HL, Dreij K. In vivo
micronucleus screening in zebrafish by flow cytometry. Mutagenesis 2016; 31:643-653. [DOI: 10.1093/mutage/gew032] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|
9
|
Sahu SC, Njoroge J, Bryce SM, Zheng J, Ihrie J. Flow cytometric evaluation of the contribution of ionic silver to genotoxic potential of nanosilver in human liver HepG2 and colon Caco2 cells. J Appl Toxicol 2016; 36:521-31. [DOI: 10.1002/jat.3276] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Revised: 11/09/2015] [Accepted: 11/09/2015] [Indexed: 11/11/2022]
Affiliation(s)
- Saura C. Sahu
- Division of Toxicology, Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition; U. S. Food and Drug Administration; Laurel MD 20708 USA
| | - Joyce Njoroge
- Division of Toxicology, Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition; U. S. Food and Drug Administration; Laurel MD 20708 USA
| | | | - Jiwen Zheng
- Division of Chemistry and Material Sciences, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health; U.S.Food and Drug Administration; Silver Spring MD 20993 USA
| | - John Ihrie
- Division of Public Health Information and Analytics, Office of Analytics and Outreach, Center for Food Safety and Applied Nutrition; U.S. Food and Drug Administration; College Park MD 20740 USA
| |
Collapse
|
10
|
Thougaard AV, Christiansen J, Mow T, Hornberg JJ. Validation of a high throughput flow cytometric in vitro micronucleus assay including assessment of metabolic activation in TK6 cells. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2014; 55:704-718. [PMID: 25111698 DOI: 10.1002/em.21891] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 07/22/2014] [Accepted: 07/04/2014] [Indexed: 06/03/2023]
Abstract
Genotoxicity is an unacceptable property for new drug candidates and we employ three screening assays during the drug discovery process to identify genotoxicity early and optimize chemical series. One of these methods is the flow cytometric in vitro micronucleus assay for which protocol optimizations have been described recently. Here, we report further validation of the assay in TK6 cells including assessment of metabolic activation. We first optimized assay conditions to allow for testing with and without metabolic activation in parallel in a 96-well plate format. Then, we tested a set of 48 compounds carefully selected to contain known in vivo genotoxins, nongenotoxins and drugs. Avoidance of irrelevant positives, a known issue with mammalian cell-based genotoxicity assays, is important to prevent early deselection of potentially promising compounds. Therefore, we enriched the validation set with compounds that were previously reported to produce irrelevant positive results in mammalian cell-based genotoxicity assays. The resulting dataset was used to set the relevant cut-off values for scoring a compound positive or negative, such that we obtained an optimal balance of high sensitivity (88%) and high specificity (87%). Finally, we tested an additional set of 16 drugs to further probe assay performance and 14 of them were classified correctly. To our knowledge, the present study is the most comprehensive validation of the in vitro flow cytometric micronucleus assay and the first to report parallel assessment with metabolic activation in reasonable throughput. The assay allows for rapidly screening novel compounds for genotoxicity and is therefore well-suited for use in early drug discovery projects. Environ.
Collapse
Affiliation(s)
- Annemette V Thougaard
- Department of Exploratory Toxicology, H. Lundbeck A/S, Ottiliavej 9, DK-2500, Valby, Denmark
| | | | | | | |
Collapse
|
11
|
Sahu SC, Njoroge J, Bryce SM, Yourick JJ, Sprando RL. Comparative genotoxicity of nanosilver in human liver HepG2 and colon Caco2 cells evaluated by a flow cytometricin vitromicronucleus assay. J Appl Toxicol 2014; 34:1226-34. [DOI: 10.1002/jat.3065] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 07/19/2014] [Accepted: 07/20/2014] [Indexed: 01/31/2023]
Affiliation(s)
- Saura C. Sahu
- Division of Toxicology, Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition; US Food and Drug Administration; Laurel MD 20708 USA
| | - Joyce Njoroge
- Division of Toxicology, Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition; US Food and Drug Administration; Laurel MD 20708 USA
| | | | - Jeffrey J. Yourick
- Division of Toxicology, Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition; US Food and Drug Administration; Laurel MD 20708 USA
| | - Robert L. Sprando
- Division of Toxicology, Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition; US Food and Drug Administration; Laurel MD 20708 USA
| |
Collapse
|
12
|
Brüsehafer K, Rees BJ, Manshian BB, Doherty AT, O’Donovan MR, Doak SH, Jenkins GJS. Chromosome Breakage Induced by the Genotoxic Agents Mitomycin C and Cytosine arabinoside is Concentration and p53 Dependent. Toxicol Sci 2014; 140:94-102. [DOI: 10.1093/toxsci/kfu058] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|
13
|
Gonzalez L, Lukamowicz-Rajska M, Thomassen LCJ, Kirschhock CEA, Leyns L, Lison D, Martens JA, Elhajouji A, Kirsch-Volders M. Co-assessment of cell cycle and micronucleus frequencies demonstrates the influence of serum on thein vitrogenotoxic response to amorphous monodisperse silica nanoparticles of varying sizes. Nanotoxicology 2013; 8:876-84. [DOI: 10.3109/17435390.2013.842266] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
|
14
|
Yao J, Gao Q, Mi Q, Li X, Miao M, Cheng P, Luo Y. In vitro micronucleus assay for the analysis of total particulate matter in cigarette smoke: comparison of flow cytometry and laser scanning cytometry with microscopy. Mutat Res 2013; 755:120-5. [PMID: 23770001 DOI: 10.1016/j.mrgentox.2013.05.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Revised: 05/17/2013] [Accepted: 05/26/2013] [Indexed: 10/26/2022]
Abstract
The possible genotoxicity of the total particulate matter (TPM) in cigarette smoke has typically been evaluated using the in vitro micronucleus assay. In recent years, automated scoring techniques have been developed to replace the manual counting process in this assay. However, these automated scoring techniques have not been applied in routine genotoxicity assays for the analysis of TPM to improve the assay efficiency. Chinese hamster ovary (CHO) cells were treated with TPM produced from 14 types of cigarettes at five concentrations (25-200μg/ml) without exogenous metabolic activation. The three following methods were used to score the micronucleus (MN) frequency: (a) flow cytometry with SYTOX and EMA dyes, which differentially stain micronuclei and apoptotic/necrotic chromatin to enhance assay reliability; (b) laser scanning cytometry with FITC and PI dyes, which is a system that combines the analytical capabilities of flow and image cytometry; and (c) visual microcopy with Giemsa dye. The test results obtained using the three methods were compared using correlation analysis. The key findings for this set of compounds include the following: (a) both flow cytometry- and laser scanning cytometry-based methods were effective for MN identification, (b) the three scoring methods could detect dose-dependent micronucleus formation for the 14 types of TPM, and (c) the MN frequencies that were measured in the same samples by flow cytometry, laser scanning cytometry, and visual microscopy were highly correlated, and there were no significant differences (p>0.05). In conclusion, both flow cytometry and laser scanning cytometry can be used to evaluate the MN frequency induced by TPM without exogenous metabolic activation. The simpler and faster processing and the high correlation of the results make these two automatic methods appropriate tools for use in in vitro micronucleus assays for the analysis of TPM using CHO cells.
Collapse
Affiliation(s)
- Jianhua Yao
- Faculty of Environmental Science and Engineering, Kunming University of Science & Technology, Kunming 650224, China
| | | | | | | | | | | | | |
Collapse
|
15
|
Elhajouji A, Lukamowicz-Rajska M. Flow cytometric determination of micronucleus frequency. Methods Mol Biol 2013; 1044:209-35. [PMID: 23896879 DOI: 10.1007/978-1-62703-529-3_11] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
During the last two decades the micronucleus (MN) test has been extensively used as a genotoxicity screening tool of chemicals and in a variety of exploratory and mechanistic investigations. The MN is a biomarker for chromosomal damage or mitotic abnormalities, since it can originate from chromosome fragments or whole chromosomes that fail to be incorporated into daughter nuclei during mitosis (Fenech et al., Mutagenesis 26:125-132, 2011; Kirsch-Volders et al., Arch Toxicol 85:873-899, 2011). The simplicity of scoring, accuracy, amenability to automation by image analysis or flow cytometry, and readiness to be applied to a variety of cell types either in vitro or in vivo have made it a versatile tool that has contributed to a large extent in our understanding of key toxicological issues related to genotoxins and their effects at the cellular and organism levels. Recently, the final acceptance of the in vitro MN test guideline 487 (OECD Guideline for Testing of Chemicals, In vitro mammalian cell micronucleus test 487. In vitro mammalian cell micronucleus test (MNVIT). Organization for Economic Cooperation and Development, Paris, 2010) together with the standard in vivo MN test OECD guideline 474 (OECD Guideline for The Testing of Chemicals, Mammalian erythrocyte micronucleus test no. 474. Organization for Economic Cooperation and Development, Paris, 1997) will further position the assay as a key driver in the determination of the genotoxicity potential in exploratory research as well as in the regulatory environment. This chapter covers to some extent the protocol designs and experimental steps necessary for a successful performance of the MN test and an accurate analysis of the MN by the flow cytometry technique.
Collapse
Affiliation(s)
- Azeddine Elhajouji
- Genetic Toxicology and Safety Pharmacology, Preclinical Safety, Novartis Institutes for Biomedical Research, Basel, Switzerland
| | | |
Collapse
|
16
|
Lukamowicz M, Kirsch-Volders M, Suter W, Elhajouji A. In vitro primary human lymphocyte flow cytometry based micronucleus assay: simultaneous assessment of cell proliferation, apoptosis and MN frequency. Mutagenesis 2011; 26:763-70. [PMID: 21791709 DOI: 10.1093/mutage/ger044] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
In order to minimise the number of positive in vitro cytogenetic results which are not confirmed in rodent carcinogenicity tests, biological systems that are p53 and DNA repair proficient should be recommended. Moreover, an appropriate cytotoxicity parameter for top dose selection should be considered. Recent International Conference on Harmonisation draft S2 and Organisation for Economic Co-operation and Development (OECD) 487 guideline accepted the in vitro micronucleus test (MNT) as a valid alternative method for in vitro chromosome aberration test within the in vitro cytogenetic test battery. Since mitosis is a prerequisite for expression of the micronuclei, it is compulsory to demonstrate that cell division occurred, and if possible, to identify the cells that completed mitosis. The OECD guideline recommends the use of a cytokinesis block for the assessment of proliferation in primary T-lymphocytes. The work presented in this manuscript was initiated to develop a novel flow cytometry-based primary human lymphocyte MNT method. This new assay is based on a three-step staining procedure: carboxyfluorescein succinimidyl ester as a proliferation marker, ethidium monoazide for chromatin of necrotic and late apoptotic cells discrimination and 4,6-diaminodino-2-phenylindole as a DNA marker. The proof of principle of the method was performed using genotoxic and non-genotoxic compounds: methyl methanesulfonate, mitomycin C, vinblastine sulphate, cyclophosphamide, sodium chloride and dexamethasone. It has been shown that the new flow cytometry-based primary human lymphocyte MNT method is at least equally reliable method as the standard Cytochalasin B MNT. However, further validation of the assay using a wide selection of compounds with a variety of mechanisms of action is required, before it can be used for regulatory purposes. Moreover, a miniaturisation of the technology may provide an additional advantage for early drug development.
Collapse
Affiliation(s)
- Magdalena Lukamowicz
- Genetic Toxicology and Safety Pharmacology, Preclinical Safety, Novartis Institutes for Biomedical Research, Werk Klybeck, Klybeckstrasse 141, CH-4057 Basel, Switzerland.
| | | | | | | |
Collapse
|
17
|
Kirsch-Volders M, Plas G, Elhajouji A, Lukamowicz M, Gonzalez L, Vande Loock K, Decordier I. The in vitro MN assay in 2011: origin and fate, biological significance, protocols, high throughput methodologies and toxicological relevance. Arch Toxicol 2011; 85:873-99. [PMID: 21537955 DOI: 10.1007/s00204-011-0691-4] [Citation(s) in RCA: 177] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Accepted: 03/01/2011] [Indexed: 12/13/2022]
Abstract
Micronuclei (MN) are small, extranuclear bodies that arise in dividing cells from acentric chromosome/chromatid fragments or whole chromosomes/chromatids lagging behind in anaphase and are not included in the daughter nuclei at telophase. The mechanisms of MN formation are well understood; their possible postmitotic fate is less evident. The MN assay allows detection of both aneugens and clastogens, shows simplicity of scoring, is widely applicable in different cell types, is internationally validated, has potential for automation and is predictive for cancer. The cytokinesis-block micronucleus assay (CBMN) allows assessment of nucleoplasmic bridges, nuclear buds, cell division inhibition, necrosis and apoptosis and in combination with FISH using centromeric probes, the mechanistic origin of the MN. Therefore, the CBMN test can be considered as a "cytome" assay covering chromosome instability, mitotic dysfunction, cell proliferation and cell death. The toxicological relevance of the MN test is strong: it covers several endpoints, its sensitivity is high, its predictivity for in vivo genotoxicity requires adequate selection of cell lines, its statistical power is increased by the recently available high throughput methodologies, it might become a possible candidate for replacing in vivo testing, it allows good extrapolation for potential limits of exposure or thresholds and it is traceable in experimental in vitro and in vivo systems. Implementation of in vitro MN assays in the test battery for hazard and risk assessment of potential mutagens/carcinogens is therefore fully justified.
Collapse
Affiliation(s)
- Micheline Kirsch-Volders
- Laboratorium voor Cellulaire Genetica, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium
| | | | | | | | | | | | | |
Collapse
|