Human blinking ‘eye-on-a-chip’

Abstract

Purpose : The structural and environmental complexity of the ocular surface (OS) poses critical technical challenges to in vitro investigation of its physiology and pathology using traditional cell culture models. As a result, research in this area has relied heavily on expensive and time-consuming in vivo animal studies. To realize more physiological in vitro models, we have developed an ‘eye-on-a-chip’ microdevice that recapitulates the three-dimensional (3D) tissue structure, dynamic mechanical environment, and physiological functionality of the human OS.

Methods : Our microdevice (Fig. A) contains a 3D dome-shaped porous cell culture scaffold with a similar curvature to that of the human cornea (Fig. B). The porous scaffold was impregnated with human keratocytes (HKs) and collagen gel to mimic the stroma. We also developed a novel microengineering technique to precisely deposit human corneal epithelial cells (HCECs) and conjunctival epithelial cells (HCjEs) on the 3D scaffold surface to replicate the concentric epithelial patterns in vivo. These microengineered ocular tissues were integrated with a biomimetic hydrogel eyelid, and the eyelid was actuated to slide along the curved scaffold surface to replicate eye blinking.

Results : The 3D tissue structures of the OS were reconstituted in our microdevice. The HKs were cultured within the porous scaffold to replicate the stroma (Fig. C). Our cell patterning technique allowed us to generate a circular corneal epithelium surrounded by a conjunctival epithelium on the curved scaffold surface (Fig. D). These ocular epithelia exhibited differentiated phenotypes as evidenced by stratification, tight junction formation, and increased cytokeratin/mucin protein expressions. We also demonstrated tear fluid dynamics in our microdevice by showing spreading of artificial tear fluid and resultant wetting of the scaffold surface due to eyelid actuation (Fig. E). Finally, we explored the possibility of leveraging this microdevice to simulate pathological features of dry eye disease and to examine key biological processes mediating the development and progression of the disease.

Conclusions : Our ‘eye-on-a-chip’ holds great potential to serve as an innovative modeling platform that represents a predictive and low-cost alternative to conventional cell culture and animal models.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.