DEVELOPMENT OF IMPROVED EPIOCULAR™ TEST PROTOCOLS FOR SCREENING OF SEVERE OCULAR IRRITANTS.
This study by scientists at MatTek Corp. demonstrated how MatTek’s EpiOcular in vitro human corneal tissue equivalent, in addition to being an excellent test for determining the ocular irritation of ultra-mild to moderate irritants, can also be used to measure the ocular irritation potential of severe irritants by making several changes to the testing protocol. The EpiOcular (OCL-200) in vitro human ocular epithelium model is capable of distinguishing between severe, moderate, mild and non-irritant substances, and addresses ICCVAM and ECVAM concerns related to long term reproducibility. While the EpiOcular model excels at benchmarking the ocular irritancy potential of materials in the moderate to ultramild range, greater ability to discriminate between levels of severe ocular irritants (e.g. severe, very severe) is desirable for testing of some household products and industrial chemicals. The current work by MatTek scientists describes efforts to develop an improved protocol for testing of severe ocular irritants with the EpiOcular model. The standard EpiOcular prediction model is based upon the time required for test chemicals to reduce the viability of EpiOcular cultures to 50% of untreated controls (ET50) after continuous exposure (i.e. leave-on treatment protocol). MatTek scientists explored new protocols that specify brief chemical treatments followed by chemical removal and extended culture time prior to viability assessment (rinse-off treatment protocol). Water miscible chemicals with in vivo Draize ocular scores of between 24-108 were chosen from the ICCVAM “Recommended List of Substances for Validation of In Vitro Test Methods for the Identification of Ocular Corrosives/Severe Irritants” . Treatment times ranging from 5 sec. to 10 min. were used, followed by extensive rinsing and extended culture for 24 hrs prior to viability evaluation by the MTT assay and determination of the ET50. This protocol allows for development of continuing culture damage or possible recovery of the cultures after chemical removal.
Draize, ECVAM, ET50, EpiOcular, High throughput screening formats, ICCVAM, Long term reproducibility, MTT, MTT viability, OCL-200, Ocular irritancy, Rabbit cornea, Standard EpiOcular prediction model, Standard dilution protocol, Standard neat dosing protocol
Acetone, BAC 1%, BAC 10%, BAC 5%, CPB 10%, Ethanol, Hexanol, IPA, Lactic acid, MEK, Methanol, NaOH 10%, Octanol, SDS 30%, TCA 30%, Triton 10%, Triton 5%, n-Butanol
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