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Date
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ARVO
Abstract
PURPOSE. Epithelial maturation is essential for the specificity and functionality of retinal
pigment epithelial (RPE) cell models. This study investigates how different maturation
conditions shape RPE characteristics and cellular complement biology in two commonly
used in vitro models: ARPE-19 and induced pluripotent stem cell–derived RPE (iPSC-RPE).
METHODS. ARPE-19 and iPSC-RPE cells were cultured under low maturation (LM) or high
maturation (HM) conditions. Phenotype, RPE marker expression, and functional properties
were assessed, and expression of local complement components was analyzed at
the transcript, protein, and secretion levels. Intracellular complement C3 processing was
characterized using epitope-specific antibodies.
RESULTS. HM conditions enhanced epithelial features in both models, with HM iPSC-RPE
displaying enhanced apical localization of RPE markers, polarity, reduced cilia length,
and higher transepithelial resistance. Expression and secretion of complement components
C3, FB, FH/FHL-1, and FI, as well as FH staining patterns, varied with maturation
condition. HM iPSC-RPE secreted increased levels of C3a, C3(H2O), and iC3b, whereas LM
cells retained C3 fragments intracellularly.Western blotting and immunostaining revealed
maturation-dependent C3 fragment profiles, with apical localization of C3 and intracellular
presence of the intact C3 β chain in HM iPSC-RPE, while C3 fragments were present
in LM and ARPE-19 cells.
CONCLUSIONS. HM iPSC-RPE cells most closely mimic native RPE features and provide a
robust model for in vitro studies. RPE cells exhibit cell-autonomous complement production
and maturation-dependent C3 activation profiles, providing a foundation for future
studies on C3 functionality in RPE homeostasis and retinal degeneration.
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Except where otherwised noted, this item's license is described as Attribution-NonCommercial-NoDerivatives 4.0 International