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New Solution: Ex vivo corneal model to assess drug delivery

30 August 2018

Researchers at the University of Birmingham have developed a low cost, ex vivo porcine corneal model to rapidly assess ocular drug penetration and absorption through the cornea. The assay uses tissue that is surplus to the food industry, replacing the in vivo models and better predicting the outcome in the human eye, in comparison to rabbit and rodent models.

The researchers seek industrial collaborators able to provide different classes of ocular drugs and drug penetration data to further assess how pore size and lipophilicity affect drug penetration through the cornea. Additionally, the researchers would benefit from expertise and access to any drugs/ molecules capable of enhancing drug delivery through the cornea, providing an insight into the drug transport mechanisms within the cornea.

One of the greatest obstructions to topically applied drugs in the eye is the cornea. Current methods to assess the penetration of ocular drugs rely on in vivo or ex vivo animal models (commonly rabbits or rodents), or in vitro cell culture. However, the in vivo and ex vivo models often fail to predict the outcome in the human eye due to species differences and the in vitro cell culture models do not have a comparable epithelial resistance to the human cornea. This 96 well-plate ex vivo porcine corneal model overcomes these limitations as the porcine cornea has similar permeability coefficients and epithelial resistance levels to the human eye, increasing the predictivity and relevance of the model as well as the reproducibility between assays. This fast, low cost method provides information for drug development and delivery, enabling the user to determine if the drug can pass through the cornea unaided or if it requires additional molecules to enhance penetration.

Using the ex vivo corneal assay as a primary screen in drug development enables identification of drugs with low corneal permeability, which can enable the researcher to remove the compound from development, reducing the number of compounds progressing to in vivo testing. The frequently used in vivo rabbit models cause high levels of irritation and suffering and require ~100 animals per study. The technology developer’s lab alone uses ~100 rats per year to assess ocular drug delivery. This Solution replaces the early stage animal models with surplus, readily available porcine tissue from abattoirs to create an ex vivo corneal assay that is more comparable to the human eye, increasing the applicability of the model. If human corneal tissue can be obtained for the assay instead, then no animals would be required for these studies.

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