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Paracellular and passive transcellular permeability in immortalized human corneal epithelial cell culture model

2003; Elsevier BV; Volume: 20; Issue: 1 Linguagem: Inglês

10.1016/s0928-0987(03)00173-8

1879-0720

Elisa Toropainen, Veli‐Pekka Ranta, Kati‐Sisko Vellonen, Joni Palmgrén, Anu Talvitie, Mirka Laavola, Pekka Suhonen, Kaisa Mari Hämäläinen, Seppo Auriola, Arto Urtti,

Drug Transport and Resistance Mechanisms

A cell culture model of human corneal epithelium (HCE-model) was recently introduced [Invest. Ophthalmol. Vis. Sci. 42 (2001) 2942] as a tool for ocular drug permeation studies. In this study, passive permeability and esterase activity of the HCE-model were characterised. Immortalised human corneal epithelial cells were grown on collagen coated filters under air-lift. The sensitivity of transcellular permeability to lipophilicity was tested in studies using nine β-blockers. The size selectivity of the paracellular route was investigated using 16 polyethylene glycol oligomers (PEG). An effusion-like approach was used to estimate porosity and pore sizes of the paracellular space in HCE membrane. Permeability and degradation of fluorescein diacetate to fluorescein in HCE-cells was used to probe the esterase activity of the HCE-model. Drug concentrations were analyzed using HPLC (β-blockers), LC–MS (PEGs), and fluorometry (fluorescein). Permeabilities were compared to those in the excised rabbit cornea. Penetration of β-blockers increased with lipophilicity according to a sigmoidal relationship. This was almost similar to the profile in excised cornea. No apical to basolateral directionality was seen in the permeation of β-blockers. Paracellular permeability of the HCE-model was generally slightly higher than that of the excised rabbit cornea. The HCE-model has larger paracellular pores, but lower pore density than the excised cornea, but the overall paracellular space was fairly similar in both models. The HCE-model shows significant esterase activity (i.e. fluorescein diacetate was converted to free fluorescein). These data on permeability of 27 compounds demonstrate that the barrier of the HCE-model closely resembles that of the excised rabbit cornea. Therefore, the HCE-model is a promising alternative corneal substitute for ocular drug delivery studies.