Transferability and within‐ and between‐laboratory reproducibilities of EpiSensA for predicting skin sensitization potential in vitro: A ring study in three laboratories

Abstract

The epidermal sensitization assay (EpiSensA) is an in vitro skin sensitization test method based on gene expression of four markers related to the induction of skin sensitization; the assay uses commercially available reconstructed human epidermis. EpiSensA has exhibited an accuracy of 90% for 72 chemicals, including lipophilic chemicals and pre-/pro-haptens, when compared with the results of the murine local lymph node assay. In this work, a ring study was performed by one lead and two naive laboratories to evaluate the transferability, as well as within- and between-laboratory reproducibilities, of EpiSensA. Three non-coded chemicals (two lipophilic sensitizers and one non-sensitizer) were tested for the assessment of transferability and 10 coded chemicals (seven sensitizers and three non-sensitizers, including four lipophilic chemicals) were tested for the assessment of reproducibility. In the transferability phase, the non-coded chemicals (two sensitizers and one non-sensitizer) were correctly classified at the two naive laboratories, indicating that the EpiSensA protocol was transferred successfully. For the within-laboratory reproducibility, the data generated with three coded chemicals tested in three independent experiments in each laboratory gave consistent predictions within laboratories. For the between-laboratory reproducibility, 9 of the 10 coded chemicals tested once in each laboratory provided consistent predictions among the three laboratories. These results suggested that EpiSensA has good transferability, as well as within- and between-laboratory reproducibility.

Proof of concept testing of a positive reference material for in vivo and in vitro sensitization testing of medical devices

“…In contrast, the I max of the IL-8 gene in the sesame oil extracts in the present study was close to the cutoff value and also similar to that previously reported. 22,23 The other three genes showed clear positive responses, while IL-8 levels were within expectations.…”

“…EpiSensA was performed as previously reported 9 . The LabCyte EPI‐MODEL24 (Japan Tissue Engineering Co. Ltd., Aichi, Japan) was used for the in vitro skin sensitization test.…”

Amino acid derivative reactivity assay–organic solvent reaction system: A novel alternative test for skin sensitization capable of assessing highly hydrophobic substances

“…The ADRA is a test that predicts the degree of skin sensitization based on reactions between NAC (a cysteine derivative), NAL (a lysine derivative), and a test substance. However, previous data showed that test substances with a logKow value of >6 tend to be insoluble in the reaction solution (Yamamoto et al, 2019) and that failure of a test substance to dissolve may prevent the accurate prediction of sensitization (Kreiling et al, 2017; Mizumachi et al, 2018). In addition, NAC dimers can be produced when the NAC thiol group oxidizes, which may decrease the ability to determine skin sensitization of a test substance (Akimoto et al, 2020).…”

“…Alternative methods KE1, KE2, and KE3 have a concordance rate with animal tests of approximately 80% (Urbisch et al, 2015), although they do not accurately assess hydrophobic substances (Kreiling et al, 2017; Mizumachi et al, 2018). For example, when using KeratinoSens TM test, the test substance is insoluble or it remains nondispersed, meaning that the test is unable to deal with maximum dissolution concentrations.…”

“…In general, the insolubility of test substances in the test system can produce false‐negative result in many alternative test methods. Therefore, the solubility of a test substance is an important indicator of the ability of a test to accurately determine skin sensitization (Mizumachi et al, 2018).…”