TR146 cells grown on filters as a model of human buccal epithelium: permeability of fluorescein isothiocyanate-labelled dextrans in the presence of sodium glycocholate

Abstract

The aim of the present study was to characterize the TR146 cell culture model as an in vitro model of human buccal epithelium with respect to the permeability of test substances with different molecular weights (Mw). For this purpose, the apparent permeability (Papp) values for mannitol and for fluorescein isothiocyanate (FITC)-labelled dextrans (FD) with various Mw (4000–40 000) were compared to the Papp values obtained using porcine buccal mucosa as an in vitro model of the human buccal epithelium. The effect of 10 mM sodium glycocholate (GC) on the Papp values was examined. To identify the pathways by which FD of Mw 4000–40 000 were transported, the confocal laser scanning microscope (CLSM) was used.The Papp values obtained with the TR146 cell culture model in the absence of a permeability enhancer linearly decreased with increasing Mw of the test substance from 0.65±0.055×10−8 to 44±7.5×10−8 cm/s, as the Papp values obtained with porcine buccal mucosa. In the presence of the permeability enhancer, GC, the permeability of the FD across the cultured TR146 cell culture model increased in a parabolic manner, reaching maximum at Mw 10 000. In the absence of the enhancer, only paracellular localization of FD was observed while, in the presence of GC, FD also could be detected in the cytosol of some of the superficial cells. The GC-induced enhancement of FD permeation may be partially attributed to changed permeation pathways. The present results indicate that the TR146 cell culture model is a suitable in vitro model for mechanistic permeability studies of human buccal drug permeability.