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Lester C, Hewitt NJ, Müller-Vieira U, Mayer M, Ellison C, Duplan H, Genies C, Jacques-Jamin C, Fabian E, Sorrell I, Lange D, Schepky A, Grégoire S. Metabolism and plasma protein binding of 16 straight- and branched-chain parabens in in vitro liver and skin models. Toxicol In Vitro 2020; 72:105051. [PMID: 33188879 DOI: 10.1016/j.tiv.2020.105051] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 10/24/2020] [Accepted: 11/06/2020] [Indexed: 11/25/2022]
Abstract
Parabens are alkyl esters of 4-hydroxybenzoic acid (4-HBA), with short-chain parabens used as antimicrobials in cosmetics. We investigated the impact of chain structure on skin and liver metabolism. Incubations with primary human hepatocytes and human liver S9 indicated that methyl-, ethyl-, propyl- and butylparaben were rapidly metabolized to similar metabolites, including 4-HBA plus the corresponding alcohols. Liver and EpiSkin™ S9 were used to investigate the metabolism of 16 short and long straight- and branched-chain parabens. The rate of hydrolysis generally decreased with increasing chain length in liver S9, whereas the reverse was true for EpiSkin™ S9. Chain length also correlated with the number of metabolites, with more oxidized metabolites detected from longer chain parabens. The identity of the alcohol group impacted metabolism the most, in terms of the rate of metabolism and the contribution of cofactors. The majority of parabens (13/16) exhibited high plasma protein binding (PPB) (>90%); whereas, 4-HBA PPB was 38%. PPB was related to the LogP of the parabens. In conclusion, the major and common paraben metabolite in PHH, liver S9 and EpiSkin™ S9 was 4-HBA. The rate of metabolism, type of metabolite and contribution of hydrolysis was tissue-specific (liver, skin) and was influenced by the chain length (and hence LogP), structural isomeric form (straight vs branched), and/or the identity of the alkyl group. SHORT ABSTRACT: We investigated how the chain structure of parabens affects their metabolism by liver and EpiSkin™ S9. The major and common metabolite in primary human hepatocytes, liver S9 and EpiSkin™ S9 was 4-HBA plus the corresponding alcohols. The rate of metabolism, type of metabolite and contribution of hydrolysis was tissue-specific and influenced by the chain length, structural isomeric form (straight vs branched), and/or the identity of the alkyl group. Most parabens exhibited high PPB (>90%), whereas the PPB of 4-HBA was 38%.
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Luijten M, Corvi R, Mehta J, Corvaro M, Delrue N, Felter S, Haas B, Hewitt NJ, Hilton G, Holmes T, Jacobs MN, Jacobs A, Lamplmair F, Lewis D, Madia F, Manou I, Melching-Kollmuss S, Schorsch F, Schütte K, Sewell F, Strupp C, van der Laan JW, Wolf DC, Wolterink G, Woutersen R, Zvonar Z, Heusinkveld H, Braakhuis H. A comprehensive view on mechanistic approaches for cancer risk assessment of non-genotoxic agrochemicals. Regul Toxicol Pharmacol 2020; 118:104789. [PMID: 33035627 DOI: 10.1016/j.yrtph.2020.104789] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 09/14/2020] [Accepted: 10/04/2020] [Indexed: 11/28/2022]
Abstract
Currently the only methods for non-genotoxic carcinogenic hazard assessment accepted by most regulatory authorities are lifetime carcinogenicity studies. However, these involve the use of large numbers of animals and the relevance of their predictive power and results has been scientifically challenged. With increased availability of innovative test methods and enhanced understanding of carcinogenic processes, it is believed that tumour formation can now be better predicted using mechanistic information. A workshop organised by the European Partnership on Alternative Approaches to Animal Testing brought together experts to discuss an alternative, mechanism-based approach for cancer risk assessment of agrochemicals. Data from a toolbox of test methods for detecting modes of action (MOAs) underlying non-genotoxic carcinogenicity are combined with information from subchronic toxicity studies in a weight-of-evidence approach to identify carcinogenic potential of a test substance. The workshop included interactive sessions to discuss the approach using case studies. These showed that fine-tuning is needed, to build confidence in the proposed approach, to ensure scientific correctness, and to address different regulatory needs. This novel approach was considered realistic, and its regulatory acceptance and implementation can be facilitated in the coming years through continued dialogue between all stakeholders and building confidence in alternative approaches.
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Eilstein J, Grégoire S, Fabre A, Arbey E, Géniès C, Duplan H, Rothe H, Ellison C, Cubberley R, Schepky A, Lange D, Klaric M, Hewitt NJ, Jacques‐Jamin C. Use of human liver and EpiSkin™ S9 subcellular fractions as a screening assays to compare the in vitro hepatic and dermal metabolism of 47 cosmetics‐relevant chemicals. J Appl Toxicol 2020; 40:416-433. [DOI: 10.1002/jat.3914] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Revised: 09/24/2019] [Accepted: 09/24/2019] [Indexed: 11/09/2022]
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Hewitt NJ, Grégoire S, Cubberley R, Duplan H, Eilstein J, Ellison C, Lester C, Fabian E, Fernandez J, Géniès C, Jacques-Jamin C, Klaric M, Rothe H, Sorrell I, Lange D, Schepky A. Measurement of the penetration of 56 cosmetic relevant chemicals into and through human skin using a standardized protocol. J Appl Toxicol 2019; 40:403-415. [PMID: 31867769 PMCID: PMC7027575 DOI: 10.1002/jat.3913] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 09/30/2019] [Accepted: 09/30/2019] [Indexed: 11/09/2022]
Abstract
OECD test guideline 428 compliant protocol using human skin was used to test the penetration of 56 cosmetic‐relevant chemicals. The penetration of finite doses (10 μL/cm2) of chemicals was measured over 24 hours. The dermal delivery (DD) (amount in the epidermis, dermis and receptor fluid [RF]) ranged between 0.03 ± 0.02 and 72.61 ± 8.89 μg/cm2. The DD of seven chemicals was comparable with in vivo values. The DD was mainly accounted for by the amount in the RF, although there were some exceptions, particularly of low DD chemicals. While there was some variability due to cell outliers and donor variation, the overall reproducibility was very good. As six chemicals had to be applied in 100% ethanol due to low aqueous solubility, we compared the penetration of four chemicals with similar physicochemical properties applied in ethanol and phosphate‐buffered saline. Of these, the DD of hydrocortisone was the same in both solvents, while the DD of propylparaben, geraniol and benzophenone was lower in ethanol. Some chemicals displayed an infinite dose kinetic profile; whereas, the cumulative absorption of others into the RF reflected the finite dosing profile, possibly due to chemical volatility, total absorption, chemical precipitation through vehicle evaporation or protein binding (or a combination of these). These investigations provide a substantial and consistent set of skin penetration data that can help improve the understanding of skin penetration, as well as improve the prediction capacity of in silico skin penetration models. The penetration of 56 chemicals was tested in human skin using a standard protocol. Dermal delivery correlated with the amount in the receptor fluid (RF). The impact of solvent on penetration was evaluated. Despite finite doses being applied, different profiles of cumulative absorption kinetics into the RF were observed. These data may help understand skin penetration and improve the prediction capacity of in silico skin penetration models.
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Sachinidis A, Albrecht W, Nell P, Cherianidou A, Hewitt NJ, Edlund K, Hengstler JG. Road Map for Development of Stem Cell-Based Alternative Test Methods. Trends Mol Med 2019; 25:470-481. [PMID: 31130451 DOI: 10.1016/j.molmed.2019.04.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 03/28/2019] [Accepted: 04/02/2019] [Indexed: 12/12/2022]
Abstract
Much progress has been made in establishing strategies for differentiation of induced human pluripotent stem cells (hiPSCs). However, differentiated hiPSCs are not yet routinely used for prediction of toxicity. Here, limiting factors are summarised and possibilities for improvement are discussed, with a focus on hepatocytes, cardiomyocytes, tubular epithelial cells, and developmental toxicity. Moreover, we make recommendations for further fine-tuning of differentiation protocols for hiPSCs to hepatocyte-like cells by comparing individual steps of currently available protocols to the mechanisms occurring during embryonic development. A road map is proposed to facilitate test system development, including a description of the most useful performance metrics.
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Ellison CA, Blackburn KL, Carmichael PL, Clewell HJ, Cronin MTD, Desprez B, Escher SE, Ferguson SS, Grégoire S, Hewitt NJ, Hollnagel HM, Klaric M, Patel A, Salhi S, Schepky A, Schmitt BG, Wambaugh JF, Worth A. Challenges in working towards an internal threshold of toxicological concern (iTTC) for use in the safety assessment of cosmetics: Discussions from the Cosmetics Europe iTTC Working Group workshop. Regul Toxicol Pharmacol 2019; 103:63-72. [PMID: 30653989 PMCID: PMC6644721 DOI: 10.1016/j.yrtph.2019.01.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 01/02/2019] [Accepted: 01/07/2019] [Indexed: 11/22/2022]
Abstract
The Threshold of Toxicological Concern (TTC) is an important risk assessment tool which establishes acceptable low-level exposure values to be applied to chemicals with limited toxicological data. One of the logical next steps in the continued evolution of TTC is to develop this concept further so that it is representative of internal exposures (TTC based on plasma concentration). An internal TTC (iTTC) would provide threshold values that could be utilized in exposure-based safety assessments. As part of a Cosmetics Europe (CosEu) research program, CosEu has initiated a project that is working towards the development of iTTCs that can be used for the human safety assessment. Knowing that the development of an iTTC is an ambitious and broad-spanning topic, CosEu organized a Working Group comprised a balance of multiple stakeholders (cosmetics and chemical industries, the EPA and JRC and academia) with relevant experience and expertise and workshop to critically evaluate the requirements to establish an iTTC. Outcomes from the workshop included an evaluation on the current state of the science for iTTC, the overall iTTC strategy, selection of chemical databases, capture and curation of chemical information, ADME and repeat dose data, expected challenges, as well as next steps and ongoing work.
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Grégoire S, Cubberley R, Duplan H, Eilstein J, Hewitt NJ, Jacques-Jamin C, Genies C, Klaric M, Rothe H, Ellison C, Fernandez J, Schepky A. Use of a Simple in vitro Test to Assess Loss of Chemical due to Volatility during an in vitro Human Skin Absorption Study. Skin Pharmacol Physiol 2019; 32:117-124. [PMID: 30889606 DOI: 10.1159/000497105] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 01/18/2019] [Indexed: 11/19/2022]
Abstract
BACKGROUND We tested the cutaneous distribution of 50 chemicals in frozen human skin. The mass balance (MB) values for 48% of the chemicals were < 90%, possibly due to evaporation. METHODS We confirmed the reduction in MB was due to evaporation for two chemicals tested in skin penetration experiments using a carbon filter above the skin to trap airborne chemical. An in vitro assay was used to predict the reduction in MB due to evaporation by comparing the recovery of chemicals after 4 h of incubation at room temperature in open and closed vials. RESULTS Evaporative losses in vitro correlated well with measured MBs (i.e., < 90%) in skin penetration experiments (R2 = 0.81). There was a correlation of the MB with the vapour pressure (VP) which could be used to group chemicals according to their likelihood to evaporate during the course of a skin penetration study. There was also a correlation of MB with Henry's law constants, melting and boiling points. CONCLUSION Our data support the use of a quick and simple test for volatility to account for the loss of MB in skin penetration experiment due to volatility. The best parameter to indicate the potential of a chemical to evaporate is the VP.
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Géniès C, Jamin EL, Debrauwer L, Zalko D, Person EN, Eilstein J, Grégoire S, Schepky A, Lange D, Ellison C, Roe A, Salhi S, Cubberley R, Hewitt NJ, Rothe H, Klaric M, Duplan H, Jacques-Jamin C. Comparison of the metabolism of 10 chemicals in human and pig skin explants. J Appl Toxicol 2018; 39:385-397. [PMID: 30345528 PMCID: PMC6587507 DOI: 10.1002/jat.3730] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 08/13/2018] [Accepted: 08/22/2018] [Indexed: 01/24/2023]
Abstract
Skin metabolism is important to consider when assessing local toxicity and/or penetration of chemicals and their metabolites. If human skin supply is limited, pig skin can be used as an alternative. To identify any species differences, we have investigated the metabolism of 10 chemicals in a pig and human skin explant model. Phase I metabolic pathways in skin from both species included those known to occur via cytochrome P450s, esterases, alcohol dehydrogenases and aldehyde dehydrogenases. Common Phase II pathways were glucuronidation and sulfation but other conjugation pathways were also identified. Chemicals not metabolized by pig skin (caffeine, IQ and 4‐chloroaniline) were also not metabolized by human skin. Six chemicals metabolized by pig skin were metabolized to a similar extent (percentage parent remaining) by human skin. Human skin metabolites were also detected in pig skin incubations, except for one unidentified minor vanillin metabolite. Three cinnamyl alcohol metabolites were unique to pig skin but represented minor metabolites. There were notable species differences in the relative amounts of common metabolites. The difference in the abundance of the sulfate conjugates of resorcinol and 4‐amino‐3‐nitrophenol was in accordance with the known lack of aryl sulfotransferase activity in pigs. In conclusion, while qualitative comparisons of metabolic profiles were consistent between pig and human skin, there were some quantitative differences in the percentage of metabolites formed. This preliminary assessment suggests that pig skin is metabolically competent and could be a useful tool for evaluating potential first‐pass metabolism before testing in human‐derived tissues. We have investigated the metabolism of 10 chemicals in viable pig and human skin. Phase I and II metabolic pathways were present in skin from both species. Chemicals not metabolized by pig skin were also not metabolized by human skin. Six chemicals metabolized by pig skin were also metabolized to a similar extent by human skin. Pig and human skin produced common metabolites, although some species differences were observed and as their relative amounts differed.
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Desprez B, Dent M, Keller D, Klaric M, Ouédraogo G, Cubberley R, Duplan H, Eilstein J, Ellison C, Grégoire S, Hewitt NJ, Jacques-Jamin C, Lange D, Roe A, Rothe H, Blaauboer BJ, Schepky A, Mahony C. A strategy for systemic toxicity assessment based on non-animal approaches: The Cosmetics Europe Long Range Science Strategy programme. Toxicol In Vitro 2018; 50:137-146. [DOI: 10.1016/j.tiv.2018.02.017] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 02/26/2018] [Accepted: 02/27/2018] [Indexed: 12/26/2022]
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Zeller A, Pfuhler S, Albertini S, Bringezu F, Czich A, Dietz Y, Fautz R, Hewitt NJ, Kirst A, Kasper P. A critical appraisal of the sensitivity of in vivo genotoxicity assays in detecting human carcinogens. Mutagenesis 2018; 33:179-193. [DOI: 10.1093/mutage/gey005] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 03/20/2018] [Indexed: 11/13/2022] Open
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Hewitt NJ, Utesch D. Cryopreserved rat, dog and monkey hepatocytes: measurement of drug metabolizing enzymes in suspensions and cultures. Hum Exp Toxicol 2016; 23:307-16. [PMID: 15301157 DOI: 10.1191/0960327104ht453oa] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Metabolism in fresh and cryopreserved (CP) rat, dog and monkey hepatocyte suspensions and cultures was measured using midazolam (CYP3A), tolbutamide (CYP2C), dextromethorphan (CYP2D) and p-nitrophenol (glucuronosyl S-transferases (UGT), sulphotransferases (ST)). CYP3A, CYP2C9, CYP2D6, UGT and ST enzyme functions in fresh and CP rat, dog and monkey hepatocyte suspensions were retained - CP rat hepatocytes lost some CYP2C activity but this was restored by adding NADPH or by placing the cells in culture, suggesting that the enzyme was still functional. Phase 2 activities were equivalent in fresh and CP hepatocyte suspensions. In some cases, incubation conditions increased the rate of metabolism, possibly reflecting de novo cofactor synthesis. However, this effect was substrate and species dependent and was not always the same in fresh and CP cells. CYP3A, CYP2C, CYP2D, UGT and ST activities at 24 hours of culture of rat and monkey hepatocytes were not compromised by cryopreservation. CYP3A, CYP2D but not CYP2C were lower in 24-hour cultures of CP dog hepatocytes than in fresh cells. Despite being lower than fresh cells, UGT activity in dog CP hepatocytes did not decrease from 0 to 24 hours of culture. Speciesspecific metabolism of p-nitrophenol could be demonstrated in both CP cell suspensions and cultures. In conclusion, these data suggest that the enzyme characteristics of fresh and CP hepatocytes from each species and under specific incubation conditions should be considered when carrying out metabolism studies of new compounds.
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Pant K, Bruce S, Sly J, Klug Laforce M, Springer S, Cecil M, Andrus E, Dakoulas E, Wagner VO, Hewitt NJ, Kulkarni R. Bacterial mutagenicity assays: Vehicle and positive control results from the standard Ames assay, the 6- and 24-well miniaturized plate incorporation assays and the Ames II™ assay. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2016; 57:483-496. [PMID: 27198925 DOI: 10.1002/em.22014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 03/12/2016] [Accepted: 03/12/2016] [Indexed: 06/05/2023]
Abstract
Bacterial mutation assays are conducted routinely as part of the safety assessment of new chemicals. The OECD Test Guideline (TG) 471 describes the conduct of the standard agar plate Ames assay, required for regulatory submissions. Higher throughput non-OECD 471 TG assays, such as the miniaturized plate incorporation and Ames II™ assays, can be used for prescreening purposes. We have compiled historical vehicle and positive control data generated using these methods. The historical database is comprised from experiments spanning 9 years and includes >1000 experiments from the standard Ames assay using the plate incorporation and pre-incubation methods (TA98, TA100, TA1535, TA1537, and WP2 uvrA), >50 experiments from the 6-well (TA98, TA100, TA1535, TA97a, and WP2 uvrA) and >100 experiments from the 24-well (TA98, TA100, TA102, TA1535, TA1537, and TA97a) plate incorporation assays, and >1000 experiments from the Ames II™ assay (TA98 and TAMix). Although miniaturization to a 24-well format made the measurement of control revertant colonies in TA1537 and TA1535 more difficult; this can be overcome by using an alternative strain with a higher spontaneous reversion rate (i.e., using TA97a instead of TA1537) or by increasing the number of replicate wells to 12 (for TA1535). All three miniaturized methods, including the Ames II™ assay, were responsive to known mutagens and the responses were reproducible over years of use. These data demonstrate the excellent reproducibility of the standard and miniaturized bacterial mutation assays using positive control chemicals. Environ. Mol. Mutagen. 57:483-496, 2016. © 2016 Wiley Periodicals, Inc.
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Obringer C, Manwaring J, Goebel C, Hewitt NJ, Rothe H. Suitability of the in vitro Caco-2 assay to predict the oral absorption of aromatic amine hair dyes. Toxicol In Vitro 2015; 32:1-7. [PMID: 26578466 DOI: 10.1016/j.tiv.2015.11.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 10/20/2015] [Accepted: 11/11/2015] [Indexed: 11/26/2022]
Abstract
Oral absorption is a key element for safety assessments of cosmetic ingredients, including hair dye molecules. Reliable in vitro methods are needed since the European Union has banned the use of animals for the testing of cosmetic ingredients. Caco-2 cells were used to measure the intestinal permeability characteristics (Papp) of 14 aromatic amine hair dye molecules with varying chemical structures, and the data were compared with historical in vivo oral absorption rat data. The majority of the hair dyes exhibited Papp values that indicated good in vivo absorption. The moderate to high oral absorption findings, i.e. ≥60%, were confirmed in in vivo rat studies. Moreover, the compound with a very low Papp value (APB: 3-((9,10-dihydro-9,10-dioxo-4-(methylamino)-1-anthracenyl)amino)-N,N-dimethyl-N-propyl-1-propanaminium) was poorly absorbed in vivo as well (5% of the dose). This data set suggests that the Caco-2 cell model is a reliable in vitro tool for the determination of the intestinal absorption of aromatic amines with diverse chemical structures. When used in combination with other in vitro assays for metabolism and skin penetration, the Caco-2 model can contribute to the prediction and mechanistic interpretation of the absorption, metabolism and elimination properties of cosmetic ingredients without the use of animals.
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Ramachandran SD, Vivarès A, Klieber S, Hewitt NJ, Muenst B, Heinz S, Walles H, Braspenning J. Applicability of second-generation upcyte® human hepatocytes for use in CYP inhibition and induction studies. Pharmacol Res Perspect 2015; 3:e00161. [PMID: 26516577 PMCID: PMC4618636 DOI: 10.1002/prp2.161] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 06/08/2015] [Indexed: 11/08/2022] Open
Abstract
Human upcyte® hepatocytes are proliferating hepatocytes that retain many characteristics of primary human hepatocytes. We conducted a comprehensive evaluation of the application of second-generation upcyte® hepatocytes from four donors for inhibition and induction assays using a selection of reference inhibitors and inducers. CYP1A2, CYP2B6, CYP2C9, and CYP3A4 were reproducibly inhibited in a concentration-dependent manner and the calculated IC50 values for each compound correctly classified them as potent inhibitors. Upcyte® hepatocytes were responsive to prototypical CYP1A2, CYP2B6, CYP2C9, and CYP3A4 inducers, confirming that they have functional AhR-, CAR-, and PXR-mediated CYP regulation. A panel of 11 inducers classified as potent, moderate or noninducers of CYP3A4 and CYP2B6 were tested. There was a good fit of data from upcyte® hepatocytes to three different predictive models for CYP3A4 induction, namely the Relative Induction Score (RIS), AUCu/F2, and C max,u/Ind50. In addition, PXR (rifampicin) and CAR-selective (carbamazepine and phenytoin) inducers of CYP3A4 and CYP2B6 induction, respectively, were demonstrated. In conclusion, these data support the use of second-generation upcyte® hepatocytes for CYP inhibition and induction assays. Under the culture conditions used, these cells expressed CYP activities that were equivalent to or higher than those measured in primary human hepatocyte cultures, which could be inhibited or induced by prototypical CYP inhibitors and inducers, respectively. Moreover, they can be used to predict in vivo CYP3A4 induction potential using three prediction models. Bulk availability of cells from multiple donors makes upcyte® hepatocytes suitable for DDI screening, as well as more in-depth mechanistic investigations.
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Manwaring J, Rothe H, Obringer C, Foltz DJ, Baker TR, Troutman JA, Hewitt NJ, Goebel C. Extrapolation of systemic bioavailability assessing skin absorption and epidermal and hepatic metabolism of aromatic amine hair dyes in vitro. Toxicol Appl Pharmacol 2015; 287:139-148. [DOI: 10.1016/j.taap.2015.05.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 05/07/2015] [Accepted: 05/19/2015] [Indexed: 01/20/2023]
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Abstract
The use of cryopreserved hepatocytes has increased in the last decade due to the improvement of the freezing and thawing methods, and has even achieved acceptance by the US Food and Drug Administration for use in drug metabolizing enzyme induction studies. This chapter provides an overview of the theories behind the process of cryopreservation as well as practical advice on methods to cryopreserve hepatocytes, which retain functions similar to fresh cells after thawing. Parameters, such as cell density, cryoprotectants, freezing media, storage conditions, and thawing techniques, should be critically considered. Special emphasis is put on human hepatocytes, but information for the cryopreservation of animal hepatocytes is also described.
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Wiegand C, Hewitt NJ, Merk HF, Reisinger K. Dermal Xenobiotic Metabolism: A Comparison between Native Human Skin, Four in vitro Skin Test Systems and a Liver System. Skin Pharmacol Physiol 2014; 27:263-75. [DOI: 10.1159/000358272] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Accepted: 12/30/2013] [Indexed: 11/19/2022]
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Hoppe E, Hewitt NJ, Buchstaller HP, Eggenweiler HM, Sirrenberg C, Zimmermann A, März J, Schwartz H, Saal C, Meyring M, Hecht S. A Novel Strategy for ADME Screening of Prodrugs: Combined Use of Serum and Hepatocytes to Integrate Bioactivation and Clearance, and Predict Exposure to Both Active and Prodrug to the Systemic Circulation. J Pharm Sci 2014; 103:1504-14. [DOI: 10.1002/jps.23942] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 02/18/2014] [Accepted: 02/21/2014] [Indexed: 11/09/2022]
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Nörenberg A, Heinz S, Scheller K, Hewitt NJ, Braspenning J, Ott M. Optimization of upcyte® human hepatocytes for the in vitro micronucleus assay. Mutat Res 2013; 758:69-79. [PMID: 24140631 DOI: 10.1016/j.mrgentox.2013.09.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 09/05/2013] [Accepted: 09/28/2013] [Indexed: 11/17/2022]
Abstract
"Upcyte(®) human hepatocytes" have the unique property of combining proliferation with the expression of drug metabolising activities. In our current study, we evaluated whether these cells would be suitable for early in vitro micronucleus (MN) tests. A treatment period of 96 h without a recovery period was most reliable for detecting MN formation in upcyte(®) hepatocytes from Donor 740. The basal MN rate in upcyte(®) hepatocytes varied considerably between donors (7-28%); therefore, modifications to the assay medium were tested to determine whether they could decrease inherent MN formation. Optimal medium supplements were 10 ng/ml oncostatin M for the pre-culture and recovery periods and 25 ng/ml epidermal growth factor and 10 ng/ml oncostatin M for the treatment period. Using the optimised conditions and outcome criteria, the upcyte(®) hepatocyte MN assay could correctly identify directly acting (e.g. mitomycin C, etoposide) and metabolically activated genotoxins (e.g. benzo[a]pyrene, cyclophosphamide). "True negative" and "false positive" compounds were also correctly identified as negative. The basal %MN in upcyte(®) hepatocytes from Donor 740 treated with DMSO, cyclophosphamide or MMC, was essentially unaffected by the growth stage ranging from population doublings of 14-61, suggesting that billions of cells could be produced from a single donor for standardised drug toxicity testing. In conclusion, we have established and optimised an in vitro MN test by using upcyte(®) hepatocytes to correctly identify known direct and metabolically activated genotoxicants as well as "false positives" and true negative compounds. The almost unlimited supply of cells from a single donor and optimised test conditions increase reproducibility in early and more predictive in vitro MN tests.
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Godoy P, Hewitt NJ, Albrecht U, Andersen ME, Ansari N, Bhattacharya S, Bode JG, Bolleyn J, Borner C, Böttger J, Braeuning A, Budinsky RA, Burkhardt B, Cameron NR, Camussi G, Cho CS, Choi YJ, Craig Rowlands J, Dahmen U, Damm G, Dirsch O, Donato MT, Dong J, Dooley S, Drasdo D, Eakins R, Ferreira KS, Fonsato V, Fraczek J, Gebhardt R, Gibson A, Glanemann M, Goldring CEP, Gómez-Lechón MJ, Groothuis GMM, Gustavsson L, Guyot C, Hallifax D, Hammad S, Hayward A, Häussinger D, Hellerbrand C, Hewitt P, Hoehme S, Holzhütter HG, Houston JB, Hrach J, Ito K, Jaeschke H, Keitel V, Kelm JM, Kevin Park B, Kordes C, Kullak-Ublick GA, LeCluyse EL, Lu P, Luebke-Wheeler J, Lutz A, Maltman DJ, Matz-Soja M, McMullen P, Merfort I, Messner S, Meyer C, Mwinyi J, Naisbitt DJ, Nussler AK, Olinga P, Pampaloni F, Pi J, Pluta L, Przyborski SA, Ramachandran A, Rogiers V, Rowe C, Schelcher C, Schmich K, Schwarz M, Singh B, Stelzer EHK, Stieger B, Stöber R, Sugiyama Y, Tetta C, Thasler WE, Vanhaecke T, Vinken M, Weiss TS, Widera A, Woods CG, Xu JJ, Yarborough KM, Hengstler JG. Recent advances in 2D and 3D in vitro systems using primary hepatocytes, alternative hepatocyte sources and non-parenchymal liver cells and their use in investigating mechanisms of hepatotoxicity, cell signaling and ADME. Arch Toxicol 2013; 87:1315-530. [PMID: 23974980 PMCID: PMC3753504 DOI: 10.1007/s00204-013-1078-5] [Citation(s) in RCA: 1042] [Impact Index Per Article: 94.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 05/06/2013] [Indexed: 12/15/2022]
Abstract
This review encompasses the most important advances in liver functions and hepatotoxicity and analyzes which mechanisms can be studied in vitro. In a complex architecture of nested, zonated lobules, the liver consists of approximately 80 % hepatocytes and 20 % non-parenchymal cells, the latter being involved in a secondary phase that may dramatically aggravate the initial damage. Hepatotoxicity, as well as hepatic metabolism, is controlled by a set of nuclear receptors (including PXR, CAR, HNF-4α, FXR, LXR, SHP, VDR and PPAR) and signaling pathways. When isolating liver cells, some pathways are activated, e.g., the RAS/MEK/ERK pathway, whereas others are silenced (e.g. HNF-4α), resulting in up- and downregulation of hundreds of genes. An understanding of these changes is crucial for a correct interpretation of in vitro data. The possibilities and limitations of the most useful liver in vitro systems are summarized, including three-dimensional culture techniques, co-cultures with non-parenchymal cells, hepatospheres, precision cut liver slices and the isolated perfused liver. Also discussed is how closely hepatoma, stem cell and iPS cell-derived hepatocyte-like-cells resemble real hepatocytes. Finally, a summary is given of the state of the art of liver in vitro and mathematical modeling systems that are currently used in the pharmaceutical industry with an emphasis on drug metabolism, prediction of clearance, drug interaction, transporter studies and hepatotoxicity. One key message is that despite our enthusiasm for in vitro systems, we must never lose sight of the in vivo situation. Although hepatocytes have been isolated for decades, the hunt for relevant alternative systems has only just begun.
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Hewitt NJ, Edwards RJ, Fritsche E, Goebel C, Aeby P, Scheel J, Reisinger K, Ouédraogo G, Duche D, Eilstein J, Latil A, Kenny J, Moore C, Kuehnl J, Barroso J, Fautz R, Pfuhler S. Use of Human In Vitro Skin Models for Accurate and Ethical Risk Assessment: Metabolic Considerations. Toxicol Sci 2013; 133:209-17. [DOI: 10.1093/toxsci/kft080] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Burkard A, Dähn C, Heinz S, Zutavern A, Sonntag-Buck V, Maltman D, Przyborski S, Hewitt NJ, Braspenning J. Generation of proliferating human hepatocytes using Upcyte® technology: characterisation and applications in induction and cytotoxicity assays. Xenobiotica 2012; 42:939-56. [PMID: 22524704 DOI: 10.3109/00498254.2012.675093] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
1. We have developed a novel technique which causes primary human hepatocytes to proliferate by transducing them with genes that upregulate their proliferation. 2. Upcyte(®) hepatocytes did not form colonies in soft agar and are not immortalised anchorage-independent cells. Confluent cultures expressed liver-specific proteins, produced urea and stored glycogen. 3. CYP activities were low but similar to that in 5-day cultures of primary human hepatocytes. CYP1A2 and CYP3A4 were inducible; moreover, upcyte(®) hepatocytes predicted the in vivo induction potencies of known CYP3A4 inducers using the "relative induction score" prediction model. Placing cells into 3D culture increased their basal CYP2B6 and CYP3A4 basal activities and induction responses. 4. Phase 2 activities (UGTs, SULTs and GSTs) were comparable to activities in freshly isolated hepatocytes. 5. Upcyte(®) hepatocytes were markedly more sensitive to the hepatotoxin, α-amanitin, than HepG2 cells, indicating functional OATP1B3 uptake. The cytotoxicity of aflatoxin B(1), was decreased in upcyte(®) hepatocytes by co-incubation with the CYP3A4 inhibitor, ketoconazole. Upcyte(®) hepatocytes also differentiated between ten hepatotoxic and eight non-hepatotoxic compounds. 6. In conclusion, upcyte(®) hepatocyte cultures have a differentiated phenotype and exhibit functional phase 1 and 2 activities. These data support the use of upcyte(®) hepatocytes for CYP induction and cytotoxicity screening.
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Götz C, Hewitt NJ, Jermann E, Tigges J, Kohne Z, Hübenthal U, Krutmann J, Merk HF, Fritsche E. Effects of the genotoxic compounds, benzo[a]pyrene and cyclophosphamide on phase 1 and 2 activities in EpiDerm™ models. Xenobiotica 2011; 42:526-37. [DOI: 10.3109/00498254.2011.643255] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Dahl EL, Curren R, Barnett BC, Khambatta Z, Reisinger K, Ouedraogo G, Faquet B, Ginestet AC, Mun G, Hewitt NJ, Carr G, Pfuhler S, Aardema MJ. The reconstructed skin micronucleus assay (RSMN) in EpiDerm™: Detailed protocol and harmonized scoring atlas. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2011; 720:42-52. [DOI: 10.1016/j.mrgentox.2010.12.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Accepted: 12/02/2010] [Indexed: 11/17/2022]
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Pfuhler S, Kirst A, Aardema M, Banduhn N, Goebel C, Araki D, Costabel-Farkas M, Dufour E, Fautz R, Harvey J, Hewitt NJ, Hibatallah J, Carmichael P, Macfarlane M, Reisinger K, Rowland J, Schellauf F, Schepky A, Scheel J. Corrigendum to ‘A tiered approach to the use of alternatives to animal testing for the safety assessment of cosmetics: Genotoxicity. A COLIPA analysis’ [Regulatory Toxicology and Pharmacology 57 (2010) 315–324]. Regul Toxicol Pharmacol 2010. [DOI: 10.1016/j.yrtph.2010.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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