Abstract
Purpose :
Age related macular degeneration (AMD) is a leading cause of vision loss in the elderly. Atrophic -or dry- AMD, the most common form of AMD, is currently without therapeutic options. Accumulation of A2E, and subsequent exposure to blue light (430nm) are considered key environmental factors leading to progressive retinal pigment epithelium (RPE) damage, followed by cell death in the aging retina, and disease development. Advances in hiPSC differentiation into RPE have opened new venues for modeling retinal pathologies. We therefore sought to develop an in vitro dry AMD model suitable for high-throughput screening (HTS) analysis, using chronic exposure to A2E and blue light.
Methods :
RPE cell differentiation from hiPSC was performed as previously described. hiPSC-RPE was characterized for key marker expression and cell purity, while function was assessed with a phagocytosis assay. Pigmented hiPSC-RPE monolayer were subjected to long term treatment with A2E (2w), followed by chronic blue light exposure (1-2w) in a 96wp format. Oxidative stress, anti-oxydant response, complement activation and inflammatory markers were monitored.
Results :
hiPSC-RPE expressed the key markers MITF, PMEL17 and ZO-1 in a majority of cells. Phagocytosis of pH-rhodo labelled bioparticles was evidenced in 50%-70% of the cells. Over the course of A2E treatment, ROS production was modulated in a dynamic pattern, in parallel with SOD2 expression. Complement activation (such as C3 and C5) was increased, as well as inhibitors of the complement pathway (such as CFH and CFI) at both RNA and protein levels. Inflammatory markers (such as IL-8 and ICAM-1) were also sharply upregulated. Following, blue light chronic exposure, progressive RPE cell death was observed.
Conclusions :
In this in vitro model of dry AMD, hiPSC-RPE is subjected to chronic, long term environmental stresses, which mimick those playing key roles in disease development in vivo. The outcomes observed in terms of oxidative stress, complement activation, inflammation and progressive RPE cell death reproduce hallmarks of dry AMD development, suggesting that this model could be useful for discovery of therapeutics. Further development is under way to validate the 96wp assay in pilote studies using small molecule libraries.
This is a 2020 ARVO Annual Meeting abstract.