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SKIN IRRITATION : Human Skin Model Test

OECD 439

PRINCIPLE OF THE TEST

The test chemical is applied topically to a three-dimensional RhE model, comprised of non-transformed human-derived epidermal keratinocytes, which have been cultured to form a multilayered, highly differentiated model of the human epidermis. It consists of organized basal, spinous and granular layers, and a multilayered stratum corneum containing intercellular lamellar lipid layers representing main lipid classes analogous to those found in vivo.

Chemical-induced skin irritation, manifested by erythema and oedema, is the result of a cascade of events beginning with penetration of the stratum corneum and damage to the underlying layers of keratinocytes. The dying keratinocytes release mediators that begin the inflammatory cascade which acts on the cells in the dermis, particularly the stromal and endothelial cells. It is the dilation and increased permeability of the endothelial cells that produce the observed erythema and oedema . The RhE-based test methods measure the initiating events in the cascade.

Cell viability in RhE models is measured by enzymatic conversion of the vital dye MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, Thiazolyl blue; CAS number 298-93-1], into blue formazan salt that is quantitatively measured after extraction from tissues (25). Irritant chemicals are identified by their ability to decrease cell viability below defined threshold levels (i.e. ≤ 50%, for UN GHS Category 2). Depending on the regulatory framework and applicability of the Test Guideline, chemicals that produce cell viabilities above the defined threshold level, may be considered non-irritants (i.e. > 50%, No Category).

 

OCDE 439 P1040248

Price

€€

Turnaround

4 weeks

€ : < 1500 € €€ : between 1500 and 4000 € €€€ : between 4000 and 20000 € €€€€ : > 20000 €
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