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N.Z. Mehenti, M.C. Peterman, T. Leng, M.F. Marmor, M.S. Blumenkranz, S.F. Bent, H.A. Fishman; A Retinal Interface Based on Neurite Micropatterning for Single Cell Stimulation . Invest. Ophthalmol. Vis. Sci. 2003;44(13):5069.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Current retinal prostheses are based on electrical stimulation, usually in the form of a microelectrode array, to generate a field potential that locally depolarizes groups of neurons. Although this method has produced visual sensations in blind subjects, the stimulation of a single cell or dendrite will be important if high spatial resolution is to be achieved. Our purpose is to quantitatively investigate whether micropatterning techniques can create an electrical interface that addresses single cells with individual microelectrodes. Methods: Soft lithographic techniques such as microcontact printing have been used for directing neural growth processes along laminin patterns to contact individual microelectrodes and achieve single cell stimulation. Retinal ganglion cells (RGC) from P7 Sprague-Dawley rats were isolated and purified through retinal dissection followed by a series of immunopanning steps. Extracellular electrical stimulation of the RGCs was detected using fluorescence imaging techniques. Nerve regeneration was also investigated as a means to direct dendrites of layered retinal cells through polymer scaffolds onto the stimulating chip. Results: The RGCs were seeded on the micropatterned arrays and neurite outgrowth has been directed along the laminin pattern to individual microelectrodes. Threshold currents were measured to be on the order of a 3-7 µA, an order of magnitude lower than those found for equidistant cell somas that were not patterned to the microelectrode. Electrical requirements for selective stimulation of RGCs were characterized, allowing the design and fabrication of microelectrode arrays with embedded tissue engineering constructs for directed neurite growth. Conclusions: The proposed retinal prosthetic interface allows for higher resolution stimulation with lower power requirements than achieved by current devices, and could be easily extended to neural prosthetics in general.
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