MatTek scientists will be attending and presenting posters at the 57th Congress of the European Toxicologists and European Societies of Toxicology in Ljubljana, Slovenia. Read more to see what they’ve been working on and request copies of their posters. We can’t wait to see you at EUROTOX 2023!
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EpiOcular time-to-toxicity test method for eye hazard subcategorization
S. Letasiova, L. Hudecova, J. Markus, Y. Kaluzhny, E. Adriaens, M. Klausner. MatTek In Vitro Life Science Laboratories, s.r.o., Bratislava, Slovakia, MatTek Corporation, Ashland, Massachusetts, United States of America, Adriaens Consulting BVBA, Aalter, Belgium
Abstract: Historically, the rabbit Draize eye irritation test (OECD TG 405) has been used to assess eye irritation and more severe ocular damage following exposure to test materials and finished products. In 2015, OECD TG 492, based on reconstructed human cornea-like epithelium (RhCE), was accepted as an in vitro alternative. However, this method could not distinguish between chemicals causing serious eye damage (GHS category 1 (Cat 1)) and less-severe eye irritation (GHS category 2 (Cat 2)). Recently, OECD TG 492B was accepted which to distinguish between materials that: a) do not require labeling, i.e. non-irritants (No Cat), b) cause serious eye damage (Cat 1), and c) eye irritants (Cat 2) according to the UN GHS ocular hazard categories. The current work expands the predictive capability of the EpiOcular™ tissue model and utilizes a time-to-toxicity (TtT) method to categorize liquid and solid chemicals according to the three UN GHS categories. The method is based on the protocol used in the CON4EI project to develop prediction models for liquids and solids (based on a set of 38 liquids and 42 solids). Additional chemicals were tested within the ALT4EI project, and another set of chemicals was added in 2022. In total, 144 reference chemicals, 78 liquids and 66 solids, were used to confirm the TtT testing strategy. The TtT testing strategy for liquids correctly identified 78.7% of Cat 1 (N=27), 63.5% of Cat 2 (N=26) and 82.0% of No Cat (N=25) and the TtT testing strategy for solids correctly predicted 75.0% of Cat 1 (N=28), 59.4% of Cat 2 (N=16) and 80.3% of No Cat (N=22). Overall, 76.8% of Cat 1 (N=55), 61.9% of Cat 2 (N=42), and 81.2% of No Cat (N=47) were correctly predicted. The EpiOcular™ time-to-toxicity test method is a novel approach for subcategorizing both liquid and solid compounds. The TtT prediction models have proven capable of successfully distinguishing chemicals and mixtures into 3 UN GHS ocular hazard categories: No Cat, Cat 2, and Cat 1.
Development of an in vitro test method for irritation of medical devices used in the oral cavity
M. Puskar, J. Molignano, C. Pellevoisin, S. Letasiova, M. Klausner. MatTek In Vitro Life Science Laboratories, Bratislava, Slovakia, MatTek Corporation, Ashland, Massachusetts, United States of America
Abstract: Any medical device (MD) intended for use in oral cavity needs to be evaluated. This project focuses on development and validation of in vitro assay to assess the oral irritation of MDs. This assay is intended to replace historical in vivo assay performed on Syrian hamsters. The ISO 10993-23 standard requires in vitro irritation testing based on reconstructed human epidermis (RhE) for evaluation of MDs prior to animal or human patch testing is performed. However, RhE models are not appropriate for MDs designed for use in oral cavity, therefore ISO recommends use of other in vitro models produced from relevant cells. EpiOral tissue model consists of normal, human-derived oral epithelial cells cultured to form multilayered, highly differentiated model of the human buccal tissue. Produced commercially for more than 15 years, several methods have been developed to study oral penetration, drug delivery, and irritancy of oral care products such as toothpastes, mouthwashes, and orthodontic devices. To assess the feasibility of an in vitro method, initial experiments tested solutions of irritant chemicals contained in MDs designed for oral cavity. Increasing concentrations of ethanol, lactic acid, methyl methacrylate, sodium dodecyl sulfate (SDS), phosphoric acid, sodium hypochlorite, hydrogen peroxide, and chlorhexidine digluconate in NaCl or sesame oil were applied to the EpiOral model. The time required to reduce tissue viability by 50% (ET-50), was determined. The results showed a clear relationship between tissue viability and exposure time and between ET-50 and concentration of the irritant chemical. Compared to historical in vivo data, the in vitro method classified the samples containing an irritant at the expected concentration. In addition, the ET-50s allowed differentiation between strong and mild irritants. The data demonstrate that this in vitro assay has equivalent or superior performance to in vivo method. The next step of the project is to assess the irritation potential of several marketed medical devices, some of which are known to induce irritant responses in vivo. We welcome other stakeholders (producer of medical devices, regulators, and other interested parties) to join us as we further develop the assay method and move it into the validation process.
Development and Validation of in vitro Human Inhalation Toxicity Tests for Volatile Liquids, Mists, and Sprays
M. Spacir1, S. Valasikova1, Y. Kaluzhny2, J. Markus1, C. Pellevoisin2, G. R. Jackson2, P. Kearney2, M. Klausner2, A. Armento2 1 MatTek In Vitro Life Science Laboratories, s.r.o., Bratislava, Slovakia 2 MatTek Corporation, Ashland, Massachusetts, United States of America
Abstract: In vivo animal models are currently accepted by regulatory authorities for acute respiratory toxicity (ART) testing. However, animal tests have been discredited as predictors of human responses on physiological and ethical grounds.The goal of this work was to develop physiologically relevant ART tests utilizing the EpiAirway™ tissue model, to demonstrate correlation to OECD accepted GHS categorization, and investigate interlaboratory reproducibility. Test articles (TA,n=53) were applied to EpiAirway tissues produced at MatTek (USA) and IVLSL (Slovakia) with two ART protocols, the Direct Application Protocol (DAP) for exposure to mists/sprays, and the Vapor Cap Protocol (VCP) for exposure to vapors/volatile liquids. In both protocols, tissues were exposed for 4h to 4 fixed doses (diluted in corn oil or water) to mimic in vivo rat exposure; followed by 20h post-incubation. The effects on tissue viability (MTT assay) and barrier properties (Transepithelial Electrical Resistance, TEER) were determined. The effective doses which reduced tissue viability by 25% (ED-25) or by 50% (ED-50) were mathematically interpolated for the DAP and VCP methods, respectively, and correlated to the GHS categories. In the DAP, TAs were applied to the apical surface. Using the MTT assay, the DAP discriminated between GHS Cat.1&2/3&4/5&NCwithaSensitivity/Specificity/Accuracy (S/S/A) of 63.5/76.1/69.8% (MatTek) and 63.8/76.1/70.0% (IVLSL). Utilizing the changes in TEER, the DAP discriminated between GHS categories with a S/S/A of 65.9/76.7/71.3% (MatTek) and 64.1/76.6/70.3% (IVLSL).The correlation coefficient between the two laboratories was R2=0.91 for MTT and 0.76 for TEER. In the VCP, TAs were applied to an absorbent material in a special cap that forms a tight seal above the tissue allowing exposure to TA vapor. Using the MTT assay, the VCP discriminated between GHS categories with S/S/A of 70.8/83.2/77.0 (MatTek) and 71.9/83.2/77.5% (IVLSL).Utilizing the changes in TEER, the VCP discriminated between GHS categories with a S/S/A of 64.4/78.5/71.5 (MatTek) and 67.1/80.1/73.6 (IVLSL).The correlation coefficient between the laboratories was R2=0.96 for MTT and 0.93 for TEER.