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Jenni J. Hakkarainen, Vytautas Cepla, Agne Ziniauskaite, Ramunas Valiokas, Giedrius Kalesnykas; Development of an artificial cornea for testing drug candidate permeability in early stages of drug development. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4337.
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© ARVO (1962-2015); The Authors (2016-present)
The cornea efficiently restricts permeability of topically administered drugs into the eye. Currently, permeability of drug candidates is tested across excised animal corneas ex vivo or using in vitro cell culture models. The purpose of this study was to develop an artificial cornea for drug permeability screening in early drug development that more adequately resembles the human cornea.
Several modifications of artificial corneas were prepared using different hydrogel cross-linking and coating techniques. The apparent permeability coefficient (Papp) values of standard reference molecules across artificial corneas were tested using Navicyte vertical diffusion chambers. Permeability characteristics (tightness, dynamic range) of the artificial cornea was assessed, and the Papp values across artificial cornea were correlated with those of ex vivo rabbit corneas and in vitro human corneal epithelial cell (HCE-T) culture model. HCE-T cells were also grown on top of artificial cornea to represent the biological equivalent of cornea. Permeability properties and expression of tight junction proteins were quantified using identical permeability set-up and immunofluorescent staining.
By modifying the hydrogel composition, we could decrease the Papp values of reference molecules ≥ 60%. Further modification of the artificial cornea resulted in a similar Papp value of the high permeability reference molecule (17 ± 3 × 10-6 cm/s, mean±SEM, p<0.001) as the Papp value across rabbit cornea. With the hydrophobic coating, the Papp value of the high permeability reference molecule could be significantly increased (52 ± 1 × 10-6 cm/s, p<0.001). However, the tightness of the artificial cornea remained 7 to 46 times higher than observed for the in vitro HCE-T model or ex vivo rabbit corneas, respectively. HCE-T cells proliferated and expressed tight junction proteins when grown on top of artificial cornea.
These data suggest that an artificial cornea may be used to replace ex vivo permeability testing using animal corneas, given the resemblance between the artificial and the human cornea with regard to drug permeability characteristics. However, further optimization of the hydrogel composition are required to fully validate the permeability characteristics of the artificial cornea.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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