Perforated microelectrode arrays implanted in the regenerating adult central nervous system

Adult mammalian optic nerve axons are able to regenerate, when provided wit h the permissive environment of an autologous peripheral nerve graft, which is usually the sciatic nerve. This study demonstrates the ability of adult rat optic nerve axons to regenerate through the preformed perforations of a polyimide electrode carrier implanted at the interface between the proxim al stump of the cut optic nerve and the stump of the peripheral nerve piece used for grafting. Evidence that retinal ganglion cells regenerated their axons through the perforated electrode carrier was obtained by retrograde l abeling with a fluorescent dye deposited into the sciatic nerve graft beyon d the nerve-carrier-nerve junction. The number of regenerating cells could be enhanced by injecting neuroprotective drugs like aurintricarboxylic acid and cortisol intravitreally. A second line of evidence was obtained by imm unohistochemical staining with antibodies to neurofilament. Third, electric al activity of the regenerating nerves was recorded after stimulating the r etina with a flash of light. The results suggest that a regenerating centra l nerve tract may serve as an experimental model to implant artificial micr odevices to monitor the physiological and topographical properties of neuri tes passing through the device or to stimulate them, thus interfering with their potential to grow. This study reports for the first time that the opt ic nerve has unique properties, which aids in the realization of these goal s. (C) 2001 Academic Press.