Study Design of EpiSkin-In Vitro Skin Irritation (OECD 439)
The EpiSkin-In Vitro Skin Irritation Test, based on the OECD Guideline 439, is another validated alternative to animal testing for assessing the irritating potential of chemicals and mixtures. It utilizes reconstructed human epidermis (RhE) models, such as EpiSkin™, to predict their ability to cause transient and reversible damage to the skin, similar to what humans experience from mild rashes or redness.
Test System:
Similar to EpiSkin-In Vitro Skin Corrosion, this test also uses the commercially available EpiSkin™ RhE model.
Test Procedure:
- Test substance preparation: Similar to the corrosion test, the test substance is prepared in appropriate concentrations and dilutions according to the OECD 439 protocol.
- Application to EpiSkin™: The test substance is applied topically to the surface of the EpiSkin™ model in specific volumes and exposure times.
- Incubation: The EpiSkin™ model is incubated under controlled conditions for a predetermined period, typically 48 hours, to allow the test substance to interact with the tissue.
- Viability and cytokine release assessment: After incubation, the viability of the EpiSkin™ cells is assessed using a vital dye, similar to the corrosion test. Additionally, the model is analyzed for the release of pro-inflammatory cytokines, which are indicators of skin irritation.
Scoring and Interpretation:
- Data on cell viability and cytokine release are combined and analyzed using a scoring system.
- The test substance is classified into different irritation categories based on the degree of damage and inflammation observed:
- Non-irritating: Minimal or no cell damage and low cytokine release.
- Irritant: Moderate cell damage and increased cytokine release.
- Borderline: Intermediate effects requiring further testing or data analysis.
Benefits:
- Reduced animal use: Eliminates the need for live animals, aligning with ethical considerations and animal welfare principles.
- Cost-effective: Generally faster and less expensive compared to traditional in vivo studies.
- Standardized protocol: Ensures international harmonization and data comparability.
- Predictive accuracy: Proven to be reliable in predicting skin irritation potential with good sensitivity and specificity.
Limitations:
- Similar to the corrosion test, limitations arise from the simplified tissue model lacking certain complexities of the human skin.
- Not suitable for all chemicals, especially strong oxidizing agents or highly volatile substances.
- Validation ongoing for some specific chemical categories.
Additional Resources:
