In Vitro Irritation Assay

In Vitro Irritation Assay testing is a non-animal method used to evaluate the potential of medical device materials to cause skin irritation. It typically involves applying extracts of the device to a reconstructed human epidermis (RHE) model and measuring cell viability using assays like MTT. This approach aligns with ethical testing practices and regulatory expectations, offering a reliable alternative to traditional animal-based irritation tests. It is especially relevant for devices that come into contact with skin or mucosal surfaces, ensuring they do not provoke adverse local reactions.

Why This Testing is Performed

This test is conducted to:

• Assess the irritation potential of medical devices without using animal models.
• Ensure patient safety by identifying materials that may cause skin inflammation or damage.
• Comply with regulatory requirements for biocompatibility, particularly for surface-contacting devices.

It supports risk assessment during product development and regulatory submission.

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Steps in Conducting In Vitro Irritation Testing

1. Extract Preparation: Device materials are extracted in a solvent per ISO 10993-12.
2. Model Exposure: The extract is applied to a human skin model (e.g., SkinEthic™ RHE or EpiDerm™).
3. Incubation: The model is incubated to allow interaction with the test substance.
4. Viability Assessment: Cell viability is measured using the MTT assay, which reflects cytotoxicity.
5. Interpretation: A reduction in viability below a defined threshold indicates irritation potential

Standards, Guidance, and Regulations

• ISO 10993-23:2021: The primary standard for in vitro irritation testing of medical devices.
• ISO 10993-12: Specifies extraction conditions for preparing test samples.
• OECD TG 439: Provides general guidance for in vitro skin irritation using reconstructed human epidermis models.