Age-related macular degeneration (AMD) is the leading cause of blindness among older adults. It has been suggested that mitochondrial defects in the retinal pigment epithelium (RPE) underlies AMD pathology. To test this idea, we developed primary cultures of RPE to ask whether RPE from donors with AMD differ in their metabolic profile compared with healthy age-matched donors. Analysis of gene expression, protein content, and RPE function showed that these cultured cells replicated many of the cardinal features of RPE in vivo. Using the Seahorse Extracellular Flux Analyzer to measure bioenergetics, we observed RPE from donors with AMD exhibited reduced mitochondrial and glycolytic function compared with healthy donors. RPE from AMD donors were also more resistant to oxidative inactivation of these two energy-producing pathways and were less susceptible to oxidation-induced cell death compared with cells from healthy donors. Investigation of the potential mechanism responsible for differences in bioenergetics and resistance to oxidative stress showed RPE from AMD donors had increased PGC1α protein as well as differential expression of multiple genes in response to an oxidative challenge. Based on our data, we propose that cultured RPE from donors phenotyped for the presence or absence of AMD provides an excellent model system for studying "AMD in a dish". Our results are consistent with the ideas that (i) a bioenergetics crisis in the RPE contributes to AMD pathology, and (ii) the diseased environment in vivo causes changes in the cellular profile that are retained in vitro.

Age-related macular degeneration (AMD), the leading cause of vision loss in the elderly, is characterized by loss of the retinal pigment epithelium (RPE). While the disease mechanism remains unclear, prior studies have linked AMD with RPE mitochondrial defects and genetic polymorphisms in the complement pathway. This study used RPE generated from induced pluripotent stem cells (iPSC-RPE), which were derived from human donors with or without AMD and genotyped for the complement factor H (CFH) AMD high-risk allele (rs1061170, Y402H) to investigate whether donor disease state or genotype had a detrimental effect on mitochondrial function and inflammation. Results show that cells derived from donors with AMD display decreased mitochondrial function under conditions of stress and elevated expression of inflammatory markers compared to iPSC-RPE from individuals without AMD. A more pronounced reduction in mitochondrial function and increased inflammatory markers was observed in CFH high-risk cells, irrespective of disease state. These results provide evidence for a previously unrecognized link between CFH and mitochondrial function that could contribute to RPE loss in AMD patients harboring the CFH high-risk genotype.

Primary cultures of retinal pigment epithelium (RPE) from human adult donors (haRPE) and induced pluripotent stem cell derived-RPE (iPSC-RPE) are valuable model systems for gaining mechanistic insight and for testing potential therapies for age-related macular degeneration (AMD). This study evaluated the treatment response of haRPE and iPSC-RPE to oxidative stress and potential therapeutics addressing mitochondrial defects. haRPE and iSPC-RPE were derived from donors with or without AMD. Mitochondrial function was measured after treatment with menadione, AICAR, or trehalose and the response to treatment was compared between cell models and by disease status. In a subset of samples, haRPE and iPSC-RPE were generated from the same human donor to make a side-by-side comparison of the two cell models’ response to treatment. Disease-specific responses to all three treatments was observed in the haRPE. In contrast, iPSC-RPE had a similar response to all treatments irrespective of disease status. Analysis of haRPE and iPSC-RPE generated from the same human donor showed a similar response for donors without AMD, but there were significant differences in treatment response between cell models generated from AMD donors. These results support the use of iPSC-RPE and haRPE when investigating AMD mechanisms and new therapeutics but indicates that attention to experimental conditions is required.