Abstract
Abstract: :
Purpose:RPE cell transplantation represents a potential treatment for ARMD. Delivery of isolated cells does not produce an ideal functioning monolayer in vivo due to poor cellular attachment, apoptosis and differentiation. Addressing this problem we have been studying how to deliver a functioning monolayer intact from the outset, with an underlying substrate with suitable mechanical properties to replace the native damaged Bruch’s membrane. We have therefore studied the design and modification of polymer membrane materials required to provide a monolayer of RPE cells suitable for cell transplantation. Methods:Two commercially availably non–degradable polyurethanes were used which were cast into thin films or electrostatically spun to form porous films. Surface modification of the materials by air plasma treatement using a commercially available capacitor plate plasma system (Emitech K1050 X Plasma Asher) was performed. Following plasma treatment the samples were immersed in sterile distilled water for 24 hours. Dynamic contact angle measurements were performed using a Cahn DCA–322 contact angle analyser to assess the effect of the plasma treatment on the surface of the substrates. Both treated and untreated samples were incubated with human wild type RPE cells and the ARPE–19 cell line for 1, 2, 3 and 7 days and were assessed for cellular adhesion, proliferation and cytotoxicity. Cellular morphology was also assessed with phase contrast microscopy and immuno–fluorescent staining. Results:Plasma treatment increased the hydrophilicity of the materials, which was demonstrated with decreasing advancing angle for Pellethane from 93° to 61.5° and the receding angle decreasing from 80° to 34.5°. Plasma treatment of both Pellethane and Tecoflex films significantly increased adhesion of RPE cells (p<0.001). Proliferation of RPE cells on the treated surfaces reached confluence by 3 days whereas no confluent cultures were observed within 14 days on the untreated materials. Phase contrast microscopy and immunochemical staining revealed that the confluent RPE cells formed a characteristic mosaic monolayer with clearly defined circumferential actin staining. Conclusions:Polyurethane substrates have suitable mechanical properties for this application and can be surface modified to enhance RPE monolayer formation.
Keywords: retinal pigment epithelium • transplantation • age–related macular degeneration