Multi-corneal barriers-on-a-chip to recapitulate eye blinking shear stress forces

Abstract

Human corneal epithelium coexists tear fluids and shows its barrier functionality under the dynamic conditions of eye blinking. However, the current in vitro cell culture settings for corneal epithelial cells lack the dynamic flow conditions to recapitulate shear stress of eye blinking, hindering corneal function evaluation. We developed a microfluidic platform enabling the dynamic culture of the human corneal barrier with recapitulation of eye blinking. The device consisted of upper and lower channels separated by a porous membrane. Human corneal epithelial cells (HCE-T) were seeded on a porous membrane in an upper channel and cultured for ten days. The cells formed a barrier with high expression of zonula occludens 1 (ZO-1) tight junction protein on day seven, and the translocation of fluorescein sodium across the barrier in the microfluidic device was comparable to that in the transwell system. Then, bidirectional and unidirectional flows were applied in the upper and lower channels, respectively, and the cells in the upper channels were stimulated with 0.6 dyn s cm-2 of shear stress. While the fluid stimuli after 24 h did not affect cell adhesion, the flow stimuli facilitated the expression of cytokeratin 19 (CK-19) intermediate filaments in cells after 24 h, indicating strengthening of the barrier function. Furthermore, the morphological single-cell analysis revealed an increase in cell body area rather than nuclei. We envision that this multicorneal barriers-on-a-chip device will unlock new possibilities in ophthalmic drug development and will be useful for studying the mechanobiology of the ocular surface.