3-Dimensional Tissue Construct Assays for Ocular Irritation: EpiOcular and HCE
3-D human tissue constructs, such as the EpiOcular (MatTek) and SkinEthic (EpiSkin), are organotypic in vitro reconstructed human cornea-like epithelium (RhCE) models used to evaluate the potential ocular irritation of test material. Viability of the EpiOcular or HCE tissues 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 negative control cultures.
In vitro RhCE models, such as the EpiOcular and HCE are made from human-derived cells, which are cultured on specially designed cell culture inserts. The cells differentiate to form a multi-layered structure which closely models the corneal epithelium (see picture below).
MTT, a vital dye, is actively taken up by the EpiOcular or HCE tissues and subsequently reduced in the mitochondria of living cells. This chemical reaction produces a purple-colored formazan within the cells, causing the live tissues to turn deep purple in color. The colored dye can be extracted from the cells and the absorbance read spectrophotometrically. For specific assay procedures, please see Step-by-Step.
Assay Design: Quick Facts
Assay Models: EpiOcular (Mattek) and SkinEthic HCE (EpiSkin) organotypic 3-D tissue constructs
Endpoint: ET50 (or t50) (the exposure time that induces a 50% reduction in viability, relative to negative controls)
Eye Irritation Test (EIT) using EpiOcular RhCE model to identify chemicals not requiring classification and labeling for eye irritation damage
Applications: For more information about testing your materials using this assay, click here.
Specialized protocols may be prepared as requested through consultation with an IIVS Study Director.
Learn about our tiered testing approach to assessing the eye irritation potential for EPA pesticide products.