Abstract
Abstract: :
Purpose: We have previously shown an in vitro cell culture model that utilizes SIRC cell line grown on polycarbonate based [Costar Transwell (TW)] membranes as an alternative to rabbit corneal membranes. The purpose of the present study was to compare the TW filters with polyester based [Costar Transwell Clear (TWC)] filters with regard to their morphology and permeability characteristics using pilocarpine (PC) and benzalkonium chloride (BAK) as model compounds. Methods: TW and TWC filter inserts were seeded with SIRC rabbit corneal cells, suspended in maintenance medium, incubated in a humidified incubator (5% CO2, 37oC) for 10 days. All inserts were fed on day 7 in culture. The inserts were rinsed with phosphate buffered saline (PBS), pH 7.3 and placed into microwell plates containing PBS, pH 7.3. Pilocarpine with or without BAK was inoculated into each insert, which were covered and returned to the incubator for 30, 60 or 120 minutes. Light microscopy was performed on hematoxylin and eosin-stained cross-sections. The permeability of pilocarpine in the presence or the absence of BAK across SIRC layers grown on TW and TWC filters was assessed by a reverse phase HPLC. Results: A single inoculation of SIRC rabbit corneal cells resulted in the formation of multiple epithelioid cell layers, simulating the clinical situation. No significant differences in the morphological characteristics were noted between the TW and TWC filters exposed to either pilocarpine alone or to pilocarpine with BAK. The apparent permeability coefficient values for pilocarpine with or without BAK were higher across TW-grown SIRC cell layers when compared to TWC-grown layers. The flux enhancement ratios in the presence of BAK were 1.08 and 1.07 for TW and TWC filter types, respectively. Conclusion: The results suggest that TW and TWC filters were comparable with respect to their morphological and permeability characteristics and can be used for corneal drug transport assessment.
Keywords: 372 cornea: epithelium