MATTEK’S TISSUE MODELS: NEW DEVELOPMENTS.

MatTek commercially offers three organotypic tissue models for irritancy and mechanistic studies: 1) EpiDerm™, a highly differentiated, keratinocyte-only model of the epidermis, 2) MelanoDerm™, a second generation version of EpiDerm in which functioning melanocytes have been incorporated, and 3) EpiOcular™, a three-dimensional, non-cornified epithelial tissue model which has been useful in predicting ocular irritancy in vitro. Previously, correlation of EpiOcular results yielded a useful “prediction model” which consisted of an equation from which one could calculate a Draize score based on in vitro MTT EpiOcular results. However, certain classes of materials (e.g. alcohol containing) were shown to be over-predicted by the assay. In addition, other assay protocols have been proposed which did not involve dilution of the test materials. Results comparing three different assay protocols run head-to-head will be presented along with an alternative correlation for alcohol-containing materials. Regarding EpiDerm, new immuno-histochemical results show that the oncogene, c-fos, and the tumor suppressor gene, p-53, are expressed following treatments known to induce carcinogenesis in animal studies. In addition, a new “long life” maintenance medium for EpiDerm has been developed which maintains normal epidermal structure for up to 2 weeks following shipment. A recent addition to the EpiDerm line of tissues, EPI-201*, will be introduced. EPI-201 is a three-day-less-mature version of EpiDerm. Results with EPI-201 show that it can be cultured after storage and shipping to yield tissue which is histologically and functionally identical to standard EpiDerm. As such, it is believed that EPI-201 will prove to be a valuable tool to study modulators of epidermal differentiation.

Carcinogenesis, Cosmetic Personal Care Products, Cutaneous irritancy, Cutaneous irritation, Cutaneous toxicity, Dermal irritancy, Dermal irritancy testing, Dermal irritation, Differentiation, cellular, Draize prediction model, Draize scores, Draize tests, Endpoints, MTT, Epi-200, Epi-201/Epi-200 PD (partially differentiated), EpiDerm, EpiOcular, Eye irritation, MTT, MTT ET-50 tissue viability assay, MTT assay, Melanin, MelanoDerm, Melanocytes, Melanogenesis, Ocular irritancy testing, Ocular irritation, Ocular irritation testing, Oncogenes, c-fos, Pre-validation, Prediction model, Prevalidation, Skin irritancy, Skin irritation, Tumor suppressor genes, Tumor(s), Validation