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C.M. Sheridan, Y. Krishna, D. Kent, I. Grierson, R. Williams; Surface Modified Expanded Polytetrafluoroethylene as a Substrate for Retinal Pigment Epithelial Cell (RPE) Growth and Function . Invest. Ophthalmol. Vis. Sci. 2006;47(13):896.
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© ARVO (1962-2015); The Authors (2016-present)
AMD is the main cause of irreversible vision loss in Europe and the USA. Transplantation of healthy RPE under the failing macula represents a potential treatment. However, since delivery of isolated cells can cause serious complications, we investigated methods to establish an intact functioning RPE monolayer on an underlying artificial substrate that can substitute for damaged native Bruch’s membrane. In this study we investigated the ability of surface modified expanded polytetrafluoroethylene (ePTFE), a fluoropolymer which is already used clinically in non–ophthalmic fields, in promoting the growth and function of healthy RPE monlayers.
ePTFE was cut into 3mm diameter discs and surface modified by ammonia gas plasma treatment using a half–wave helical resonator plasma system. Following treatment, the samples were placed in distilled water for 24 hours. Human ARPE–19 cells were seeded onto untreated and treated samples and then incubated at 37oC with 5% CO2. RPE growth and monolayer formation were optimised on the treated ePTFE surfaces by use of differentiating agents and reduction of serum levels. When cells were known to have reached confluence, functionality testing of the RPE monolayers on the treated surfaces was assessed. Formation of cell–cell junctions, transepithelial electrical resistance (TEER) and the ability of monolayers to phagocytose photoreceptor outer segments (POS) where investigated at set time intervals.
Plasma treatment enhanced cell adhesion and growth, reaching confluence by Day 7. Treatment of RPE cells on the ePTFE surfaces during their growth phase with retinoic acid enhanced monolayer formation with homogeneous coverage of the substrate surface and tight cell packing. Well–defined Z0–1, pancadherin staining were evident by day 7. TEER measurements continued to rise reaching a maximum by Day 10 and then plateau. Furthermore, the RPE monolayers were able to demonstrate phagocytosis of POS in a time–dependent manner.
ePTFE can be surface modified to support an intact monolayer of healthy RPE cells with normal morphology and with the ability to perform RPE–specific functions. With further investigation ePTFE may be considered for use in transplantation.
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