The human bronchial epithelial cell line 16HBE14o-as a model system of the airways for studying drug transport

The 16HBE14o− cell line, which forms polarised cell layers in vitro, provides a promising opportunity to develop a convenient epithelial cell culture model in which respiratory drug transport can be evaluated in vitro. This study investigated the effect of cell seeding density, collagen substratum and time in culture on the development of barrier properties in this cell line, after which the permeability of the 16HBE14o− cell layers to a series of solutes was studied. Seeding cells at a density of 2.5×105 cells per cm2 on a monofibrillar Vitrogen-100 collagen substratum, followed by culture at an air–liquid interface for 6 days resulted in cell layers with a transepithelial electrical resistance (TER) of 247±47 Ω cm2 and an apparent permeability coefficient of 2.5×10−6 cm s−1 for mannitol. The permeability of the 16HBE14o− cells to hydrophilic molecules (log P<1.9) was of an order of magnitude greater than that of typical alveolar cell cultures, possibly reflecting barrier properties more representative of the airways. More lipophilic drugs showed higher permeabilities indicating a sigmoidal relationship between permeability and lipophilicity similar to that observed for solute transport across primary cultured epithelial cell layers. These results indicate that under appropriate culture conditions, 16HBE14o− cell layers provide a discriminatory barrier to solute transport.