Abstract

DO.23.04

Towards prosthetic replacement of Bruch’s membrane: Comparison of polyester and electrospun nanofiber substrates

Stanzel B. V.^1,2,3, Englander M.¹, Thieltges F.³, Strick D. J.⁴, Blumenkranz M. S.¹, Holz F. G.³, Binder S.², Marmor M. F.^1
1Department of Ophthalmology, Stanford University, Stanford, CA, USA; ²L. Boltzmann Institute for Retinology and Biomicroscopic Lasersurgery, Vienna, Austria; ³University Eye Hospital Bonn, Bonn, Germany; ⁴Department of Genetics, Stanford University, Stanford, CA, USA; ⁵Department of Ophthalmology, Rudolf Foundation Clinic, Vienna, Austria

Objective: To explore two biocompatible substrates as candidates for Bruch’s membrane prosthesis, which is an important adjunct for replacement strategies of the Retinal Pigment Epithelium (RPE).
Methods: Polyester culture inserts (PET) are 10μm thick and permeable (Corning). Commercial electrospun polyamide nanofiber (EPN) inserts are adherent to impermeable plastic (Donaldson). The EPN can be detached from the plastic with ethanol to obtain free and thus permeable EPN. Scanning electron microscopy (SEM) studies were performed on all growth substrates. Fetal and aged adult human RPE cells were cultured on above substrates. RPE proliferation parameters were studied on commercial EPN and glass. RPE marker proteins were studied using immunofluorescence and immunoblotting.
Results: PET is a smooth surface with widely-spaced small pores; in contrast, EPN is a fibrillar meshwork with potential fluid transit everywhere. While total growth fractions were comparable on both substrates, DNA replication was increased on EPN as evidenced by higher BrdU incorporation. On PET, fetal cells remelanized and maintained a hexagonal monolayer over 3 months. Fetal cells grown on commercial (impermeable) EPN also showed typical RPE characteristics. In preliminary experiments, aged RPE showed better differentiation on commercial EPN than PET. Free (permeable) EPN was less supportive in most experiments, however modifications of the original setup gave promising results.
Conclusions: Fibrillar, in contrast to flat, surfaces induce higher DNA replication in RPE. Permeable PET and impermeable EPN support differentiation of RPE cells. The fibrillar surface topology of EPN, which mimics native basement membranes and appears to rejuvenate aged RPE, makes it a promising component for BM prosthetics.

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