Assessment of the Cytosensor Microphysiometer Assay in the COLIPA In Vitro Eye Irritation Validation Study

The Cytosensor(TM) microphysiometer assay and its associated prediction model were evaluated in the COLIPA ocular irritation validation study for cosmetic ingredients and formulations. Test materials were prepared in low-buffer medium and exposed to L929 cells grown in transwells. The metabolic rate of the cell population was measured after each dose and the dose inducing a 50% decrease in the rate (MRD(50)) was determined and used to predict the ocular irritation potential. Only 29 of the 55 materials could be tested because of solubility limitations. The irritancy potential of many chemical classes was underpredicted by the assay, particularly acids, bases and organics. The use of the assay for surfactants and surfactant-based formulations showed promise, confirming the use of the method for these types of materials, although some revision of the prediction model would be necessary. Excellent interlaboratory reproducibility for the MRD(50) values across all test materials was observed.