Background: Eye irritation tests with animals have been conducted for a long time. However, the subjective decision to irritation, the anatomic/physiologic difference between species and humans, and ethical issues are crucial problems. Various research groups have paid attention to alternative testing methods. In these senses, we fabricated in vitro mini-cornea models with immortalized human corneal epithelial cells (iHCECs) and keratocytes (iHCKs) and used them for irritation tests. This study hypothesized that our mini-cornea model could present different viability tendencies according to test chemicals with different irritancy levels.
Methods: Cells used in this study were characterized with cornea-specific markers by immunocytochemistry and western blot. To make a three-dimensional hemisphere construct like cornea stroma, we cultured iHCKs under modified culture conditions verified by matrix formation and total collagen content. iHCECs were seeded on the construct and cultured at an air-liquid interface. The model was treated with 2-phenoxyethanol, triton X-100, sodium lauryl sulfate, and benzalkonium chloride.
Results: iHCECs and iHCKs presented their specific cell markers. In modifying the culture condition, the group treating ascorbic acid (200 µg/ml) presented an intact cellular matrix and included the highest collagen content; thus, we used this condition to fabricate the mini-cornea model. The model shows hemisphere shape and homogenous cell distributions in histological analysis. We observed different sensitivity tendencies by types of chemicals, and the model's viability significantly decreased when the chemical concentration increased.
Conclusion: In this study, we performed and observed irritation tests using a tissue-engineered mini-cornea model and considered to apply as an alternative approach for animal tests.
Keywords: Ascorbic acid; Eye irritation; In vitro cornea model; Tissue engineering.
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