356.

EPIOCULAR™ HUMAN CELL CONSTRUCT: TISSUE VIABILITY AND HISTOLOGICAL CHANGES FOLLOWING EXPOSURE TO SURFACTANTS. Blazka¹, M., Diaco², M., Harbell², J., Raabe², H., Sizemore², A., Wilt², N., Bagley¹, D. ¹Colgate-Palmolive Co., Piscataway, NJ, USA; ²Institute for In Vitro Sciences, Inc., Gaithersburg, MD, USA. Presented at Society of Toxicology Annual Meeting, New Orleans, LA, March 6-10, 2005. The Toxicologist, 84, (1), Abstract # 2001, 409, (2005).

Keywords: Benzethonium chloride, C10-12 alcohol ethoxylate, Cellular structure, Cetyl alcohol, Cetylpyridinium bromide, Cytoplasmic staining, Didecyldimonium chloride, Draize, ET-50, EpiOcular, Eye irritation potential, Histological changes, MTT assay, Nuclear staining, Nuclear structure, Ocular irritation, Quaternium-18, Sodium lauryl sulfate, Sodium sulfolaurate, Surfactant-based formulations, Surfactants, Tissue damage, Validation program

Endpoints: Histological damage, Histology

Summary: The ability of the EpiOcular construct to predict the eye irritation potential of surfactants and surfactant-based formulations has been the subject of a formal validation program. EpiOcular correlates a test article's potential for ocular irritation with the time it takes to reduce tissue viability by 50% (ET50) as measured by the tissue's ability to reduce MTT. An algorithm is used to convert the ET50 value to a 'predicted Draize' score which can then be compared to in vivo data. This study investigated whether the histological changes following exposure are in agreement with the MTT results. Eight surfactants were selected from the validation study; 4 surfactants whose in vitro ocular irritation potential agreed with the in vivo data (cetyl alcohol; 3% sodium lauryl sulfate; 50% didecyldimonium chloride; sodium sulfolaurate mixture) and 4 whose in vitro data differed from the in vivo data (10% cetylpyridinium bromide; 3.2% benzethonium chloride; C10-12 alcohol ethoxylate; quaternium-18). Exposure times used in this study bracketed ET50 values established in the validation study. For all surfactants, the results showed a good relationship between the degree of histological damage with changes in tissue viability. An increase in the depth and severity of tissue damage was associated with a decrease in tissue viability. Histological changes ranged from subtle cellular changes such as vacuolization and punctate chromatin condensation to overt tissue loss and cell necrosis. Loss of or damage to the surface squamous epithelium was associated with <20% decrease in viability, while the degree of damage to the central squamous epithelium was directly related to a 20-80% decrease in viability. In conclusion, the nature and severity of the histological changes were in agreement with the MTT results. Understanding the progression and types of cellular changes associated with tissue damage may be able to help distinguish the degrees of ocular irritation.

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