Fig 1: Characterisation of RP11 - RPE cells revealed polarity and functional defects. a Schematic of RPE differentiation timeline; b Bright-field images of iPSC-derived RPE: representative examples from at least ten independent experiments, scale bar 100 µm; c Immunostaining for basolateral markers BEST1 and Na+/K+-ATPase: representative images from three independent experiments, scale bar 50 µm; d Correct basolateral distribution of collagen IV (C-IV) and apical MERTK in unaffected control (WT3) but not RP11 RPE cells: representative images from three independent experiments, scale bar 50 µm; e, f ELISA assays for apical and basal secretion of PEDF and VEGF, respectively, in control and RP11 - RPE cells; g Trans-epithelial resistance measurements revealed a significant difference between patient and RP11 - RPE cells; h Reduced phagocytic capacity in RP11 - RPE cells. Statistical significance is calculated for MFI (mean fluorescence intensity) values. e–h Data shown as mean ± SEM, n = 3. Statistical significance of pairwise comparisons is indicated by n.s.: not significant; ***p < 0.001; ****p < 0.0001 (Student’s paired t test). b–h Data obtained from RPE at week 21 of differentiation