Tissue Engineered Macular Edema-On-A-Chip

Abstract

Purpose : The development of advanced ocular therapeutics motivates a greater need to understand how chemicals affect retinal function. Microfluidic technology enables the generation of tissues in controlled biomimetic microenvironments. We generated an experimental model of the human outer blood-retina barrier (O-BRB) through co-culture of induced pluripotent stem cell (iPSC)-derived retinal pigment epithelium (RPE) and endothelial cells (EC) in a microfluidic platform. This platform will allow us to reproduce side effects of several systemic drugs such as Macular Edema, test candidate therapeutics for ocular indications, and observe the impact of genetic mutations on O-BRB function in specific patient populations.

Methods : This study utilizes poly(dimethylsiloxame) organ chips composed of two vertically stacked channels separated by a porous polyethylene terephthalate membrane. RPE and EC were differentiated from donors’ iPSC and seeded into apical and basolateral channels, respectively, to form a personalized model of RPE-Choroidal interface. Tissue functionality was determined using the following assays: fluid transport across RPE-EC interface, dextran permeability, cytokine secretion, and RPE morphology.

Results : iPSC-derived RPE and EC formed confluent monolayers and demonstrated aspects of barrier integrity and functionality after 4 weeks of culture. Fluid transport across the RPE-EC interface approached physiological levels of 2.5 µl/cm²h. Permeability of 3 kDa dextran molecules decreased across the RPE-Choroidal interface by the end of the culture period. Characteristic cytokines including interleukin 8, vascular endothelial growth factor, and epidermal growth factor were secreted by the cells in a polarized fashion. RPE presented hexagonal morphology and characteristic pigmentation.

Conclusions : Microfluidic technology enables non-invasive observation of ocular pathology using patient-derived cells. Specific functional aspects of ocular diseases that affect the O-BRB can now be modeled. Observable adverse effects of disease of drug treatment include defects in fluid flow across the RPE and the release of characteristic inflammatory cytokines. This study will lay the groundwork for a new drug discovery platform and a platform to test potential toxicity of drugs that lead to macular edema as a side-effect.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.