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Tea Soon Park, Eric Nguyen, Haig Pakhchanian, Davide Ortolan, Nikhil Vettikatu, Roba Dejene, Devika Bose, Genqing Liang, Ruchi Sharma, Arvydas Maminishkis, Kapil Bharti; Modeling the outer blood-retina barrier using microfluidic chips and iPSC-derived RPE and endothelial cells. Invest. Ophthalmol. Vis. Sci. 2021;62(8):2192.
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The retinal pigmented epithelium (RPE) and choroid vasculature form a highly specialized tissue that provides critical support for retinal function and homeostasis. Here, we combined human iPSC-derived RPE and endothelial cells (EC) with organ-on-a-chip technology, to model the outer blood-retinal barrier (oBRB). Using this platform, we aim to study patient-specific mechanisms of retinal degenerative disorders such as macular edema.
The commercially available Emulate organ-chip microfluidic system was used as the basis of the model. The apical channel of the chip was seeded with iPSC-derived RPE cells that had been differentiated for 42 days. ECs were deposited as a monolayer surrounding the chip basal channel to mimic the choroid capillaries. In order to characterize the functionality of the RPE-EC co-culture system in the chip, we assayed: (1) Dextran permeability, (2) fluid transport across apical to basal channels, and (3) RPE and EC morphology.
Various genetically independent healthy and diseased iPSCs were differentiated into functional RPE and EC and cryopreserved. RPE cells formed a monolayer on the membrane of the apical channel and displayed highly pigmented polygonal morphology with expression of ZO-1 and tublin-1b. RPE tight junction integrity was confirmed using a fluorochrome conjugated dextran permeability assay, demonstrating that RPE barrier function was sufficient to block Dextran molecules. In addition, a fluid transport assay was performed to examine RPE transcytosis and homeostasis function. When compared to control chips seeded with only RPE cells, the fluid transport activity in RPE-EC chips was 2-fold higher and in range of physiological levels. These results support that both EC and RPE cells are critical components of fluid transport activity.
The combination of a microfluidic organ-chip system with patient-specific iPSC derivatives has provided us with a non-invasive ex vivo model to study outer retinal physiology. This micro-engineered RPE-EC chip system is a platform for the patient-specific study of diseased RPE-EC phenotypes as well as drug discovery and toxicity screening for the treatment of ocular degenerative diseases such as macular edema.
This is a 2021 ARVO Annual Meeting abstract.
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