Study Design of EpiSkin-In Vitro Skin Corrosion (OECD 431)

The EpiSkin-In Vitro Skin Corrosion Test, based on the OECD Guideline 431, is a validated, non-animal alternative for assessing the corrosive potential of chemicals and mixtures. It utilizes reconstructed human epidermis (RhE) models, like EpiSkin™, to predict their ability to cause irreversible damage to the skin, similar to what occurs in humans.

Study Design of EpiSkin-In Vitro Skin Corrosion (OECD 431)

Test System:

EpiSkin™: A commercially available RhE model composed of non-transformed human keratinocytes cultured to form a multi-layered, differentiated epidermis closely resembling the structure and function of the human skin barrier. 


Test Procedure:

  • Test substance preparation: The test substance is prepared in appropriate concentrations and dilutions according to the OECD 431 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 24 hours, to allow the test substance to interact with the tissue.
  • Viability assessment: After incubation, the viability of the EpiSkin™ cells is assessed using a vital dye, such as MTT or NRU, to determine the extent of cell damage caused by the test substance.

Scoring and Interpretation:

  • The degree of cell damage is quantified based on the intensity of the vital dye uptake or other validated endpoints.
  • A scoring system is applied to classify the test substance into different categories according to its corrosive potential:

  • Non-corrosive: No significant cell damage observed.
  • Corrosive: Extensive cell death and destruction of the RhE structure.

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 corrosion potential with high sensitivity and specificity

Limitations:

  • Limited tissue complexity: EpiSkin™ models lack certain components of the human skin, like blood vessels and nerves, which may influence the response to some substances.
  • Not suitable for all chemicals: Certain highly volatile or reactive substances may not be adequately assessed using this method.
  • Validation limitations: Although validated for specific categories of chemicals, ongoing research and validation efforts are necessary for broader applicability.

Additional Resources:

https://www.oecd-ilibrary.org/environment/test-no-431-in-vitro-skin-corrosion-reconstructed-human-epidermis-rhe-test-method_9789264264618-en

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