Development of skin corrosion and irritation test methods employing ex vivo porcine skin model

Skin corrosion and irritation are key local toxicological responses of the skin to chemical exposure. Conventional in vivo methods have limitations such as species difference, ethical concern, and reproducibility issue, necessitating the development of reliable alternatives. We developed skin corrosion (SCT) and irritation test (SIT) methods using ex vivo porcine ear skin based on cell viability and skin barrier disruption. Test chemicals were treated on ex vivo porcine ear skin for 3 min and 60 min (SCT) or 60 min only (SIT). After 40 +/- 2 h postincubation, cell viability assay with CCK-8, and skin barrier test with FITC-dextran penetration were conducted. To evaluate the predictive capacity of the method, 38 reference chemicals (20 corrosives, 8 irritants and 10 no category chemicals) were tested. SCT achieved 96.7 % (29/30) accuracy in identifying corrosives, meeting the performance standards of OECD TG 431 In Vitro Skin Corrosion: Reconstructed Human Epidermis test. The accuracy for subcategorizing corrosive substances into categories 1 A (<25 % at 3 min) and 1B/1C (>= 25 % at 3 min, <25 % at 60 min) was 83.3 % (25/30). The accuracy of SIT identifying non-irritant (>= 50 % at 60 min) was 83.3 % (15/18). FITC-dextran penetration assay showed a similar accuracy, highlighting its value as an alternative endpoint to identify irritants. Collectively, this study demonstrated that the ex vivo porcine skin model may offer a cost-effective, and reliable alternative for skin hazard testing.