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Dermal Irritation in 3D Human Tissue Constructs

3-D reconstructed human epidermal (RHE) tissue constructs are organotypic in vitro models, which can be utilized in a variety of assays to evaluate the dermal irritation, corrosivity, cytotoxicity, phototoxicity, and/or anti inflammatory potential of test materials. Tissue viability is determined using the vital dye MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide). The reduction of MTT in treated cultures is expressed as a percentage relative to untreated (negative control) cultures.

RHE tissue constructs are made from human epithelial cells, which are cultured on specially designed cell culture inserts. The cells differentiate to form a fully differentiated epidermis, complete with a functional stratum corneum (see picture below). An advantage of using 3-D tissues is that test materials are applied topically, so solids, undiluted final formulations, and insoluble test materials can be tested.

MTT, a vitality-indicating dye, is actively taken up by the tissues and subsequently reduced in the mitochondria of living cells. This chemical reaction produces a purple-colored compound (formazan) within the cells, causing the live tissues to turn deep purple in color. For specific assay procedures, please see Step-by-Step.

Assay Design: Quick Facts

Assay Model: organotypic RHE tissue constructs

Endpoints: Relative viability by MTT reduction, ET50 * (the exposure time that induces a 50% reduction in viability, relative to solvent controls), cytokine expression, dermal penetration, others

  • For time-to-toxicity only. Alternate assay endpoints are detailed in the Applications section.

For more information about testing your materials using this assay, please see Applications.
Specialized protocols may be prepared as requested through consultation with an IIVS Study Director.

3D Tissue Incubation
Epidermal 3-D Tissue Construct Histology