The lack of physiologically relevant and controllable experimental systems has limited mechanistic understanding of age-related macular degeneration (AMD) and the development of effective therapeutic strategies. Here, we present a tunablein vitroretinal pigment epithelium (RPE) stress model that integrates engineered light delivery with lipid modulation to reproduce early AMD-like cellular pathology under standard culture conditions. Human RPE cells (ARPE-19 and iPSC-derived RPE) were exposed to precisely controlled, low-intensity light-induced oxidative stress in the presence of docosahexaenoic acid (DHA), a highly unsaturated retinal lipid, or palmitic acid (PA) as a saturated lipid control. Cellular responses were assessed using functional and structural readouts including lysosomal and mitochondrial activity, membrane integrity, epithelial morphology, tight junction organization, and lipid peroxidation. A programmable LED-based exposure system enabled fine control over light intensity, duration, and cycling, allowing delivery of sub-lethal, chronic oxidative stress. Combined light and DHA exposure selectively induced lipid peroxidation, disruption of ZO-1-defined tight junctions, and progressive loss of RPE viability, while PA-treated cells and non-retinal HuH7 hepatocytes showed minimal sensitivity. ARPE-19 cells responded rapidly, whereas iPSC-derived RPE cells exhibited delayed but comparable pathological changes, reflecting differences in cellular maturity and stress resilience. Pharmacological inhibition of ferroptosis using ferrostatin-1 significantly reduced lipid peroxidation and rescued epithelial integrity and cell viability, identifying ferroptosis as a key mechanism underlying RPE vulnerability in this system. By enabling programmable and reproducible delivery of oxidative lipid stress, this modular light-based platform provides a biofabrication-compatible framework for modeling early AMD, with potential for integration into more complex retinal constructs, co-culture systems, and high-throughput therapeutic screening pipelines.
Keywords: AMD; DHA; RPE; ferroptosis; iPSC-derived RPE; light.
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