Induced Pluripotent Stem Cell Modeling of Best Disease and Autosomal Recessive Bestrophinopathy

Purpose: To understand the pathophysiology of Best disease (BD) and autosomal recessive bestrophinopathy (ARB) by establishing an in vitro model using human induced pluripotent stem cell (iPSC). Materials and Methods: Human iPSC lines were generated from mononuclear cells in peripheral blood of one ARB patient, one autosomal dominant BD patient, and two normal controls. Immunocytochemistry and reverse transcriptase polymerase chain reaction in iPSC lines were conducted to demonstrate the pluripotent markers. After the differentiation of iPSC into functional retinal pigment epithelium (RPE), morphological characteristics of the RPE were evaluated using confocal microscopy and immunocytochemistry. The rates of fluid flow across iPSC-RPE monolayer were measured to compare apical to basal fluid transports by RPE. RNA sequencing was performed on iPSC-RPE to identify the differences in gene expression profiles, and specific gene sets were tested using Gene Set Enrichment Analysis. Results: Morphological characteristics, gene expression, and epithelial integrity of ARB iPSC were comparable to those of BD patient or normal control. Fluid transport from apical to basal was significantly decreased in ARB iPSC-RPE compared with BD iPSC-RPE or control iPSC-RPE. Gene Set Enrichment Analysis confirmed that ARB iPSC-RPE exhibited significant enrichments of epithelial-mesenchymal transition gene set and TNF-alpha signaling via NF-kappa B gene set compared to control iPSC-RPE or BD iPSC-RPE. Conclusion: A human iPSC model of ARB showed a functional deficiency rather than anatomical defects. ARB may be caused by RPE dysfunction following BEST1 mutation.