Abstract
Abstract: :
Purpose: To develop an in vitro desiccation model using both human conjunctival and corneal epithelial cell lines to assess the desiccation protection capability of various artificial tear solutions. Methods: The assay was conducted in a cell culture plate containing 96 or 48 wells. Both human corneal epithelial cell (CEPI 17) and Chang's conjunctival cell (P67 Clone) were adopted for the study. When the cells reach the confluent stage, the medium was removed and 50∼100 µl of test solution was added to each well. After 15 minutes incubation at 37ºC, the solution was removed and the cells were placed inside an airflow hood to dry for 30 to 60 minutes at room temperature. 100 or 200 µl of MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazonium bromide) viable dye was then added to each well and the plate was incubated at 37oC for 4 hours. The MTT formazan blue crystals produced by the viable cells became visible after incubation. 50 or 100 µl of acid isopropanol was added to each well to dissolve the blue precipitate after carefully removing the solution. The absorbance of each well was determined at 570 nm by a microplate reader. Wells with serum/medium and wells with vehicle solution were also run in the same plate as a total viable and a dead control, respectively. Results: Most of the formulations containing various polymers such as HPMC, dextran, etc., as demulcents are able to provide more than 80% protection efficacy after 40 to 60 minutes desiccation in both cell lines. However, the formulations preserved with either BAC or sodium perborate provided poor protection (less than 50% efficacy). Conclusion: This in vitro model/methodology offers a simple and economical procedure to quantitatively assess the desiccation protection capability of various artificial tears.
Keywords: 376 cornea: tears/tear film/dry eye