Spatiotemporal Determination of Metabolite Activities in Multiple Corneal Epithelium Barriers on a Chip

The corneal epithelial barrier maintains the metabolic activities of the ocular surface by regulating membrane transporters and metabolic enzymes responsible for the homeostasis of the eye as well as the pharmacokinetic behavior of drugs. Despite its importance, no established biomimetic in vitro methods are available to perform the spatiotemporal investigation of corneal metabolism and determine the transportation of endogenous and exogenous molecules. This study introduces multiple corneal epithelium barriers on a chip, namely, Cornea-Chip, which enables the spatiotemporal collection as well as analysis of micro-scaled extracellular metabolites from both the apical and basolateral sides of the barriers. Longitudinal samples collected during 48 h period were analyzed using untargeted liquid chromatography–mass spectrometry metabolomics method, and 104 metabolites were annotated. The shifts in extracellular metabolites and quantitative analysis of the mRNA associated with membrane transporters could allow the investigation of the correlation between the expression of and the secretion and transportation of metabolites across the polarized corneal epithelial barrier. The Cornea-Chip might provide a non-invasive, simple, and effectively informative method to determine pharmacokinetics and pharmacodynamics as well as to discover novel biomarkers for drug toxicological and safety tests as an alternative to animal experiments.