Development of a novel bio-compatible polymer film for use as a Bruch’s membrane substitute

Abstract

 

Purpose

 

To develop and optimise a co-polymer blend of poly(ethylene glycol methacrylate) (PEGM) and poly(methyl methacrylate) (PMMA) to act as a synthetic Bruch’s membrane (BrM) scaffold for primary murine retinal pigment epithelium (RPE) monolayers, as a potential treatment for dry age-related macular degeneration (AMD). This bio-compatible polymer film is designed to mimic BrM and to allow RPE cells to attach to the surface and proliferate, whilst retaining the necessary properties of human BrM, including porosity, thickness, biocompatibility and adhesion for the anchorage-dependant RPE cells.

 

Methods

 

PEGM and PMMA are biocompatible polymers which are already in use for clinical applications. This co-polymer blend is functionalised at the PEGM site with N,N’-Disuccinimidyl carbonate and a RGDS peptide to facilitate RPE attachment. Electrospinning is used to produce polymer fibre sheets. By altering the parameters of the electrospinning apparatus (voltage, distance from needle to collector, flow rate) we can control the polymer fibre production.

 

Results

 

By using the electrospinning technique, the co-polymer mat provides the necessary porosity, and by altering the parameters of the electrospinning, the thickness has been optimised to match human BrM (confirmed via an optical profiler, which found that the co-polymer had a thickness of approximately 12µm). The fidelity and effectiveness of the PMMA:PEGM co-polymer have been tested using long-term cultures of primary murine RPE monolayers. Our experiments also characterised RPE-barrier properties to establish the suitability of this novel synthetic scaffold for future transplantation studies

 

Conclusions

 

This work demonstrates synthesis of a PMMA:PEGM co-polymer film, through the use of electrospinning, which mimics the properties of the BrM (porosity, thickness, biocompatibility and adhesion). This suggests that the electrospun membrane is a viable scaffold to facilitate delivery of RPE cells to the sub-retinal space. This is an exciting prospect and future work will investigate sub-retinal delivery of the co-polymer, via use of an in house designed and manufactured injector.

 

 

Scanning electron micrograph of electrospun polymer films, showing the surface and porosity (Scale bar 10µm, x430 magnification)

 

 

Three dimensional optical profile analysis of electrospun polymer films, again showing the surface and porosity (Scale bar 120µm, x50 magnification)

 

Keywords: 412 age-related macular degeneration • 585 macula/fovea • 584 low vision