A human pluripotent stem cell-derived organ-on-a-chip model of the outer blood-retinal barrier for understanding age-related macular degeneration

Abstract

Purpose : Age-related macular degeneration (AMD) is an eye disorder of malfunctioning tissues in the outer blood-retinal barrier (oBRB): the retinal pigment epithelium (RPE), the underlying “Bruch’s membrane” and the adjacent choroidal capillary bed. To understand disease pathology and develop new therapeutic concepts, in vitro models are needed where physiological and morphological changes of tissues can easily be monitored, and conditions can be manipulated. To this end, we developed an organ-on-a-chip model (OOC) of the oBRB based on human induced pluripotent stem cell-derived cells (hiPSC) and evaluate its future use as an in vitro model of drug development for AMD.

Methods : Human iPSC-RPE and iPSC-endothelial cells (EC) were derived based on protocols from Regent et al. (2019) and Orlova et al. (2014) respectively. The PDMS-based OOC was composed of a top channel for RPE culture as a monolayer, and a bottom channel where ECs were cultured in a microvessel of a well-defined geometry patterned within collagen-I using a subtractive method of micropatterning. Expression of cell-cell adhesion markers was analyzed by immunocytochemistry, and barrier function of endothelial cells was assessed with a clinically relevant technique analogous to fluorescein angiography.

Results : OOC was fabricated using injection molding, which minimizes labor intensive fabrication and provides device consistency. Devices were placed on a rocking platform inside an incubator to facilitate gravity driven medium flow in channels. Healthy cell population growth was confirmed by cell-cell adhesion markers. EC barrier was assessed by perfusion of fluorescently labeled dextran where lower permeability compared to only RPE containing devices was observed.

Conclusions : The OOC developed in this study models the outer BRB by recapitulating the tissue microenvironment. integration of iPSC-derived cells from AMD patients could provide insights for individualized testing and the evaluation of new treatments.

This is a 2021 ARVO Annual Meeting abstract.

 

Figure 1 PDMS-based OOC of the oBRB modelling. (A-i) Fabrication of OOC where a membrane (yellow) was held between 2 channels and stabilized using magnets before PDMS injection. (A-ii) Following curing, device only requires bonding of a glass coverslip. (B) Top channel (red) was separated by a membrane from bottom (white) that consists of a patterned gel (black). Scale bar: 100µm.