Abstract
Abstract: :
Purpose: To direct the growth of isolated rat retinal ganglion cells (RGCs) for individual high-resolution stimulation at a visual prosthesis interface, using soft lithography and microcontact printing. Methods: Micropatterns of biologically active molecules were created with a final resolution of 5 µm. Patterns could be printed with growth promoters or inhibitors, allowing for directed growth of isolated rat RGCs toward a stimulation electrode. Standard photolithographic techniques were used to fabricate photoresist coated silicon substrates (molds). Poly (dimethylsiloxane) stamps for microcontact printing were formed using these molds and were used to dry transfer positive growth factors to glass and hydrophobic plastic surfaces. RGCs were purified by sequential immunopanning to greater than 99.5% purity from P7 Sprague-Dawley rats. Approximately 50,000 RGCs were seeded onto the patterned surfaces. RGCs were cultured at 37 C and 6.5% CO2 in 2 mL of serum-free medium (supplemented Neurobasal-A). In addition, poly (dimethylsiloxane) stamps were used to wet transfer colloidal carbon to glass and hydrophobic plastic surfaces for use as stimulation electrodes. Results: Using microcontact printing, we were able to direct the growth of isolated rat RGCs on both glass and hydrophobic plastic surfaces. Individual neurites were isolated and directed to grow toward colloidal carbon electrodes with this technique. We found that the best growth promoter is mouse laminin, stamped at a concentration of 50 µg/mL. Conclusion: The ability to direct the growth of RGCs to stimulation electrodes opens the possibility of a visual prosthesis interface based on the regeneration of retinal cells. This advance in surface chemistry will allow for the specific stimulation of individually addressed neurons in these future devices.
Keywords: 308 age-related macular degeneration • 415 ganglion cells • 553 regeneration