Characterization of hiPSC-RPE on a prosthetic Bruch's membrane

Purpose The Bruch’s membrane is a multilayered collagenous structure, positioned at the basal side of the retinal pigment epithelium (RPE) cells, immediately apical to the choroidal vasculature in the eye. Disruption of the integral intra-cellular communication and physiologic interaction between these cell layers results in the thickening of this membrane in both genetic and age related macular degenerative diseases. It’s positioning in the eye makes it an obligate component of any model investigating the pathophysiology of the RPE/choroid complex ex vivo. The goal of this study was to evaluate the utility of a Bombyx mori silk fibroin (BMSF) membrane to serve as a prosthetic Bruch’s membrane. Methods Human inducible pluripotent stem cells (hiPSC)-derived RPE or human fetal RPE (hfRPE), were cultured either directly on BMSF membrane or extracellular matrix (ECM)-coated BMSF membrane. After 60-90 days in culture, morphologic, gene/protein expression and functional characteristics of hiPSC-RPE and hfRPE on BMSF membrane were compared to hiPSC-RPE and hfRPE grown on ECM coated plastic/permeable support transwells that have previously been shown to display important characteristics of in vivo adult human RPE. Results Both hiPSC and hfRPE grew on BMSF membranes in culture with varied efficiency dependent on the matrix coating of the membrane. Furthermore, hiPSC-RPE and hfRPE grown on ECM-coated BMSF membrane supported RPE growth and pigmentation while BMSF alone displayed poor adhesion. Furthermore, hiPSC-RPE cultured on matrix-coated BMSF displayed numerous physical, gene/protein expression and functional characteristics akin of in vivo human adult RPE cultures. Conclusions The BMSF membrane is sufficient to support the long-term culture of RPE from both fetal and hiPSC origins and will provide a suitable Bruch’s membrane-like platform for in vitro disease modeling and in vivo cell-transplantation studies