Using the Cytosensor Microphysiometer to Assess Ocular Toxicity

Abstract

Measuring in vitro cytotoxicity is one method currently used to estimate damage to the eye after chemical exposure. The Cytosensor Microphysiometer method evaluates cytotoxicity by measuring the test material-induced reduction in the metabolic rate of L929 cells. Changes in metabolic rate are measured indirectly as a function of changes in the extracellular acidification rate of the cells. During exposure to increasing concentrations of a cytotoxic material, there is a decrease in the release of acid byproducts into the surrounding medium as the cells die. These acidic metabolic byproducts cause a measurable change in the pH of a lightly buffered medium, which can be measured by the Cytosensor Microphysiometer. The change in the pH of the medium over time is then converted into a metabolic rate estimate for the cells. The endpoint measurement from the assay is the metabolic rate decline of 50%, the MRD50 value (in units of mg/ml).

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“…The concentration reducing the metabolic rate, pH, to 50% of its basal rate, MRD50, is determined from three different runs. CM is applicable to water soluble substances and mixtures (52). With down approach for identification of severe irritants, MRD50 ≤ 2 mg/mL is considered as Category 1 (severe irritants) and MRD50>2 mg/mL means No perdition can be made.…”

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“…glucose metabolism, aminophenol and fatty acids), induced proton release in the microenvironment causes a change in pH at the extracellular environment. Cytosensors microphysiometer has the ability to measure so minor changes and can nominate changes in cellular metabolism (Nash et al, 2014). ISEs record the potential that develops on the surface of a membrane (solid or liquid) as a function of a reference system (semiconductor with known and constant potential).…”