Transport of lipophilic drug molecules in a new mucus-secreting cell culture model based on HT29-MTX cells.
OBJECTIVE
A new mucus-secreting in vitro drug absorption model based on monolayers of goblet-cell like sub-clones of the human colon carcinoma cell line HT29 obtained by methotrexate (MTX) treatment was investigated.


METHODS
Twelve sub-clones were isolated and characterized by light microscopy (LM), transelectron microscopy (TEM), confocal laser scanning microscopy (CLSM), transepithelial electrical resistance (TEER) and the transport of a paracellular marker FITC-Dextran (Mw 4400) (FD-4).


RESULTS
Significant differences of microscopical appearance, TEER-values and permeability of FD-4 between the sub-clones were evident. However, two of them, namely MTX-D1 and MTX-E12. formed tight confluent monolayers with a thick mucus-layer on the apical surface. They were used to compare the apparent permeability coefficient (Papp) of a series of lipophilic drugs, which should be affected by the mucus-layer, namely barbiturates (barbituric acid, barbital, phenobarbital, methylphenobarbital and heptabarbital) and testosterone, as a reference, to mucus-free Caco-2 cells. The permeability of drugs with a partition coefficient (log P) > 1 was decreased in the mucus-producing cell lines. Testosterone, the most lipophilic compound, showed a decrease of up to 43%.


CONCLUSIONS
We demonstrated that the mucus layer is a significant barrier to drug absorption for lipophilic drugs. In conclusion, our model may serve as a suitable in-vitro cell culture model to study the influence of the mucus layer on drug diffusion.
Behrens
I
I
Department of Pharmaceutics and Biopharmacy, University of Marburg, Germany.
Stenberg
P
P
Artursson
P
P
Kissel
T
T
D000465:Algorithms; D001463:Barbiturates / Q000737:chemistry / Q000378:metabolism; D001692:Biological Transport; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002999:Clone Cells; D004058:Diffusion; D004553:Electric Conductivity; D004847:Epithelial Cells / Q000502:physiology; D019073:HT29 Cells; D006801:Humans; D008055:Lipids / Q000737:chemistry; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D009077:Mucins / Q000096:biosynthesis / Q000235:genetics; D009093:Mucus / Q000378:metabolism / Q000502:physiology*; D004364:Pharmaceutical Preparations / Q000737:chemistry / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012995:Solubility; D019108:Tight Junctions / Q000378:metabolism
D001463:Barbiturates; D008055:Lipids; D009077:Mucins; D004364:Pharmaceutical Preparations