The Silk Protein Sericin Promotes Viability of ARPE-19 and Induced Pluripotent Stem Cell-Derived Retinal Pigment Epithelial Cellsin vitro

Abstract

Purpose: Maintaining mature and viable retinal pigment epithelial cells (RPE) in vitro has proven challenging. Investigating compounds that can promote RPE-viability and maturation is motivated by RPE transplantation research, the quest to understand RPE physiology, and a desire to modulate RPE in pathological states. We have previously reported that the silk protein sericin promotes viability, maturation, and pigmentation of human fetal RPE. In the present study, our aim was to uncover whether these effects can be seen in adult retinal pigment epithelial cell line-19 and induced pluripotent stem cell-derived RPE (iPSC-RPE).Methods: ARPE-19 and iPSC-RPE were cultured with or without 10 mg/mL sericin. After seven days, viability was assessed with calcein-acetoxymethyl ester (CAM) and ethidium homodimer-1 (EH-1) assays, flow cytometry, and morphometric analysis. Expression levels of RPE65, tyrosinase, and Pmel17 were quantified to compare maturation between the sericin-treated and control cultures.Light microscopy and staining of the tight junction protein zonula occludens protein 1 (ZO-1) were employed to study sericin's effects on RPE morphology. We also measured culture medium pH, glucose, lactate, and extracellular ion content.Results: Sericin-supplemented RPE cultures demonstrated significantly better viability compared to control cultures. Sericin appeared to improve ARPE-19 maturation and morphology in vitro. No effects were seen on RPE pigmentation with the concentration of sericin and duration of cell culture herein reported.Conclusions: This is the first study to demonstrate that supplementing the culture media with sericin promotes viability of iPSC-RPE and ARPE-19. Sericin's viability-promoting effects may have important implications for retinal therapeutics and regenerative medicine research.

Injectable Hydrogel Based on Gellan Gum/Silk Sericin for Application as a Retinal Pigment Epithelium Cell Carrier

“…The experiment results followed the same tendency as MTT assay data. As expected, ARPE-19 cells were able to proliferate in hydrogels including SS, showing a higher quantity of dsDNA compared to that in GG/SS 0% hydrogels p < 0.001­(***). Due to weight loss of hydrogels, all hydrogels showed a decrease of about 50% in the dsDNA content on day 28 compared to that on day 3.…”