Introduction: The cornea which is avascular and transparent tissue is the outer layer of the eye, accepting optical stimuli, and transferring electrochemical signals to the brain. Moreover, the cornea performed a key role in physical barriers against external risks. However, the tissue can be easily damaged and get the disease due to anatomical location. To test irritancy harmful chemicals, cosmetic products, and drugs, the animal used test was conducted for a long time. Because of dissimilarities between animals and humans, an alternative testing method was required in various countries. This research is fabricating a cornea-like in vitro model testing irritancy of chemicals for replacing animal tests and developing in vitro testing model.
Methodology: To fabricate collagen-rich matrix-like corneal stroma, immortalized human corneal keratocytes (iHCKs) were cultured with a modified medium containing a high concentration of ascorbic acid. Additionally, immortalized human corneal epithelial cells (iHCECs) were seeded on top of the matrix and cultured at an air-liquid interface for differentiated epithelial layers. The fabricated cornea model was used to test eye irritancy with toxicants.
Results: At the 2D level, immunocytochemistry (ICC) images show expression of cell-specific protein marker, and production of cell own matrix was observed as sheet foam through macro-and microscopic images. At the 3D level, histological observation and immunohistochemistry (IHC) results revealed whole shape, thickness, cellular morphology, and distribution. In the irritation test, the viability of the cornea model treating 2-phenoxyethanol, Triton X-100 (TX-100), sodium lauryl sulfate (SLS), and benzalkonium chloride (BAK) was reduced as increasing concentration of chemicals.
Conclusions: Eye irritation test with animals was conducted for a long time, but physiological dissimilarity and ethical issues were big hurdles to reflect humans. In this regard, this study was performed to verify the physiological reaction of the cornea model treating toxicants and facilitates the replacement of animal used testing methods.