A 3-DIMENSIONAL IN-VITRO MODEL FOR THE STUDY OF OCULAR CYTOTOXICITY AND IRRITANCY

A three-dimensional human tissue model has been developed in our labor atory and used as a substrate for assessing ocular cytotoxicity and ir ritancy potential. The full-thickness model is a co-culture of dermal fibroblasts and epithelial cells (keratinocytes). Metabolically and mi totically active fibroblasts are seeded onto medical-grade nylon mesh, where they attach and secrete collagen and extracellular matrix prote ins. Then, keratinocytes are seeded onto the top of this submerged str omal tissue, and the tissue grows into a multilayered epithelium. Hist ological examination of this cellular co-culture system reveals a cell ular organization similar to the rabbit/human cornea. The resulting su bstrate has been used effectively to study the effects of a variety of test compounds (surfactants, powders, creams) at diluted or full-stre ngth concentrations in a time-course assay. The protocol mimics the wa y in which in vivo animal testing (Draize eye test) is performed. The treated tissue is assayed for cytotoxicity and irritancy (MTT and PGE( 2), respectively) over a period of time. The high correlation (R > 0.8 1) of our in vitro data to existing animal eye data shows the potentia l usefulness of these tissue substrates as an in vitro alternative for evaluating the toxicity of test agents from diverse chemical classes.