TM2020-04
The RSMN is an in vitro assay developed to address the toxicity to the genome. It is an adaptation of the well-established in vivo and in vitro micronucleus tests (OECD TG 474 (OECD, 2016c) and OECD TG487 (OECD, 2016a)).
The RSMN has been designed in a three-dimensional reconstructed human skin (RHS) model: the EpiDerm™ (MatTek, Ashland, USA). The EpiDerm™ model is cultured from normal human epidermal keratinocytes derived from neo-natal foreskin tissue on specially prepared tissue culture inserts. The EpiDerm™ resembles the structure, morphology, and xenobiotic metabolism of the human epidermis (Hu et al., 2010; Gotz et al., 2012; Hewitt et al., 2013; Yuki et al., 2013) and it is of high biological relevance when assessing the genotoxic potential of test items via dermal exposure route.
The RSMN is intended to be used within regulatory genotoxicity hazard identification testing strategies to follow up positive results from the classical in vitro test battery, which is used as a first step. It is proposed to be used instead of in vivo genotoxicity test methods (e.g. OECD TG 474 (OECD, 2016c) and TG 475 (OECD, 2016b)) in the context of test items that are causing clastogenic (chromosomal breaks and translocations) or aneugenic (abnormal number of chromosomes) effects in vitro and are primarily associated with dermal exposure.
The method has a potential impact on the 3Rs. It provides a viable follow-up solution of high human relevance for testing dermally exposed chemicals, both under regulations that allow animal testing and under regulations that prohibit in vivo testing, such as the EU cosmetics regulation.
The test method has undergone a full validation process thus, the Test Submitter requested EURL ECVAM to consider the RSMN assay for peer-review. The full test submission, received in 2021, was completed in all its parts. EURL ECVAM acknowledged that the submission included a detailed test protocol (SOP) together with data annexes and bibliography describing the validation study, the properties of skin model, and strategic use of the RSMN, including in regulatory context i.e., under Cosmetics Regulation.
EURL ECVAM was able to assess the test method’s readiness to enter peer review by evaluating the completeness and quality of the information provided for each of the following relevant modules: test definition, within-laboratory reproducibility (WLR), transferability, between-laboratory reproducibility (BLR), predictive capacity and applicability domain. Suggestions for performance standards (PS) were not provided at this stage. Nevertheless, the lack of information did not affect the EURL ECVAM assessment.
The Test Submitter highlighted that the RSMN can be used together with the RS Comet assay in order to cover all genotoxicity endpoints that usually need to be addressed for regulatory purposes (gene mutation, clastogenicity, and aneugenicity).
Based on the mechanistic and biological relevance of the test method and provided information, EURL ECVAM concludes that RSMN assay is ready to undergo to peer review.
MENNECOZZI Milena;
CORVI Raffaella;
BARROSO João;
2025-12-19
Publications Office of the European Union
JRC141978
978-92-68-26304-4 (online),
OP KJ-01-25-218-EN-N (online),
https://publications.jrc.ec.europa.eu/repository/handle/JRC141978,
10.2760/4417480 (online),
