OECD 439: In Vitro Skin Irritation – Reconstructed Human Epidermis Test Method

The OECD 439 In Vitro Skin Irritation test, or Reconstructed Human Epidermis Test, is used to assess the potential for skin irritation occurring after topical exposure to a test article. Previously, this type of testing typically involved the use of laboratory animals. However, this in vitro alternative uses a three-dimensional RhE model comprised of non-transformed human-derived epidermal keratinocytes, cultured to form a multilayered, highly differentiated model of human epidermis. The study design follows the current OECD 439 guideline entitled “In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method” and can be performed in accordance with Good Laboratory Practices.

Chemical-induced skin irritation occurs due to a cascade of events that ultimately result in the destruction of keratinocytes and other skin cells. These damaged cells then react by releasing inflammatory mediators, and causing a localized inflammatory response at the site of exposure.

The RhE-based test method evaluates the extent of cell/tissue damage by quantifying cell viability. After extraction from the tissues, cell viability is measured using an enzymatic conversion of a vital dye (MTT) into a blue formazan salt. A decrease in cell viability below defined threshold levels thus identifies the test article in question as an irritant chemical.

Typically 1-2 mL or 1-2 grams of test article are required.  This test is performed in compliance with Good Laboratory Practice Regulations.

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