New Poly(-caprolactone) Scaffolds For Retinal Pigment Epithelium Transplantation

Abstract

Purpose: : Transplantation strategies aimed at replacing the degenerative retinal pigment epithelium (RPE) are promising approaches for the treatment of retinal diseases such as dry AMD. However, RPE transplants using allografts or other means have failed because Bruch’s Membrane (BrM) alterations were not addressed. Therefore, effective strategies for RPE replacement require the development of support substrates that mimic BrM properties in order to support cell graft survival and function. Here, we tested the potential of poly(ε-caprolactone) (PCL), a biodegradable polymer highly biocompatible for implantation into the subretinal space, as a substrate for RPE culture and transplantation.

Methods: : A spin-assisted templating process was used to create 10µm thick smooth PCL scaffolds. These membranes were then mounted on transwell supports and compared to polyester transwell (Costar) controls in cell culture studies. ARPE-19 cells and induced pluripotent stem (iPS) cell-derived human RPE cells (provided by Dr. Clegg, UCSB) were plated at confluence and cultured for up to 6 weeks in low serum conditions. The capacity of PCL membrane to support RPE survival and differentiation was evaluated using histology, immunohistochemistry, gene expression analysis and phagocytosis assays.

Results: : RPE cell attachment to PCL polymer was similar to the control. However, the differentiation of both ARPE-19 and iPSC-RPE on PCL membrane was improved over controls after one week of culture as demonstrated by their epithelial morphology and ZO-1 localization. The expression of secreted growth factors and genes involved in RPE differentiation or function was similarly up regulated in ARPE-19 cells plated on control transwells and PCL membranes after one and four weeks of culture. Finally, ARPE-19 cells cultured on PCL showed a significant increase in phagocytic activity compared to the control RPE.

Conclusions: : Our data indicate that a PCL membrane is able to support human RPE culture and differentiation and may constitute an ideal substrate for RPE monolayer transplantation.

Keywords: age-related macular degeneration • retinal pigment epithelium • Bruch's membrane