The EyeIRR-IS assay: Development and evaluation of an in vitro assay to measure the eye irritation sub-categorization of liquid chemicals.

Several alternative methods have been developed and regulatory adopted by OECD as in vitro alternatives to the Draize eye irritation assay either to detect chemicals not requiring classification (No Category) or inducing serious damage to the eye (Category 1) but none are sensitive enough to identify chemicals inducing reversible eye effects (category 2) which are categorised by default. Therefore, the discriminatory power of a genomic approach applied to the SkinEthic™ Human Corneal Epithelium (HCE) model was investigated to allow subcategorization capacity according to UN GHS classification. An algorithm based on gene expression modulation on a training (62) and a test (31 liquids) chemical set, tested neat and at 30%was evaluated in an assay called EyeIRR-IS.

Pre-validation of SENS-IS assay for in vitro skin sensitization of medical devices.

According to ISO 10993-1:2018, the skin sensitization potential of all medical devices must be evaluated, and for this endpoint ISO 10993-10:2010 recommends the use of in vivo assays. The goal of the present study was to determine if the in vitro SENS-IS assay could be a suitable alternative to the current in vivo assays. The SENS-IS assay uses the Episkin Large and SkinEthic RHE reconstructed human epidermis models to evaluate marker genes.

In vitro testing strategy for assessing the skin sensitizing potential of "difficult to test" cosmetic ingredients.

Before placing a new cosmetic ingredient on the market, manufacturers must establish its safety profile, in particular assessing the skin sensitization potential, which is a mandatory requirement for topical applications. Since the ban on animal testing in Europe, and its extension to many parts of the world, a battery of in vitro tests covering the key steps of the Adverse Outcome Pathway (AOP) for skin sensitization is recommended. To date, three in vitro methods are validated in the OECD guidelines (442C, 442D, 442E), and many others are under validation by OECD (2019) and ECVAM.

In vitro measurement of skin sensitization hazard of mixtures and finished products: Results obtained with the SENS-IS assays.

Product safety evaluation in the EU is based on data mainly obtained on individual ingredients. However, mixture effects have been demonstrated in numerous skin sensitization studies due to the presence of irritating chemicals or to modification of dermal absorption. To evaluate the ability of the SENS-IS assay to detect such mixture effects, we performed three sets of experiments: First, the importance of the vehicle on absorption of individual ingredients was evaluated by testing the effect of commonly used cosmetic preparations on the sensitizing potential of 3 chemical allergens and 2 fragrance blends.

SENS-IS, a 3D reconstituted epidermis based model for quantifying chemical sensitization potency: Reproducibility and predictivity results from an inter-laboratory study.

The SENS-IS test protocol for the in vitro detection of sensitizers is based on a reconstructed human skin model (Episkin) as the test system and on the analysis of the expression of a large panel of genes. Its excellent performance was initially demonstrated with a limited set of test chemicals. Further studies (described here) were organized to confirm these preliminary results and to obtain a detailed statistical analysis of the predictive capacity of the assay.