Dermal Irritation in 3-Dimensional Reconstructed Human Epidermis Tissues: EpiDerm, epiCS, EpiSkin and SkinEthic RCE
3-D reconstructed human epidermis (RhE) models such as the EpiDerm (MatTek), epiCS (CellSystems) EpiSkin and SkinEthic RHE (EpiSkin SA) are organotypic in vitro models of human epidermis 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. Viability of the tissues is determined using the vital dye MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide). The reduction of MTT in test material-treated tissues is expressed as a percentage relative to negative control-treated cultures.
The EpiDerm, epiCS, EpiSkin and RHE tissue models 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 vital dye, is actively taken up by the EpiDerm, epiCS, EpiSkin or RHE 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
Tissue Models: EpiDerm (MatTek), epiCS (CellSystems), EpiSkin and SkinEthic RHE (EpiSkin)
- Corrosivity and Skin Irritation Test assays following OECD Test Guidelines (TG 431 and TG 439, respectively).
- Skin Irritation Potential using a Time-to-Toxicity Screening protocol to determine an ET50 value (the exposure time that induces a 50% reduction in tissue viability, relative to negative or solvent controls). This approach allows for comparative skin irritation / skin tolerance evaluations for product development and product stewardship beyond the limited scope of regulatory classification and labeling tests.
- Cytokine Expression Profiles supplement the viability assessments to refine skin tolerance / skin irritation evaluations, especially for products formulated to be mild (or anticipated to have mild irritation potential).
- Anti-inflammatory Activity Screening is performed by evaluating an Active Ingredient’s ability to inhibit or reduce the release of inflammatory cytokines in tissues pre-induced with an inflammatory agent such as a phorbol ester.
- Phototoxicity for topically-applied complex formulations
For more information about testing your materials, please see Applications.
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.