title: The brain tissue response to implanted silicon microelectrode arrays is increased when the device is tethered to the skull.
abstract: The influence of tethering silicon microelectrode arrays on the cortical brain tissue reaction was compared with that of untethered implants placed in the same location by identical means using immunoflourescent methods and cell type specific markers over indwelling periods of 1-4 weeks. Compared with untethered, freely floating implants, tethered microelectrodes elicited significantly greater reactivity to antibodies against ED1 and GFAP over time. Regardless of implantation method or indwelling time, retrieved microelectrodes contained a layer of attached macrophages identified by positive immunoreactivity against ED1. In the tethered condition and in cases where the tissue surrounding untethered implants had the highest levels of ED1+ and GFAP+ immunoreactivity, the neuronal markers for neurofilament 160 and NeuN were reduced. Although the precise mechanisms are unclear, the present study indicates that simply tethering silicon microelectrode arrays to the skull increases the cortical brain tissue response in the recording zone immediately surrounding the microelectrode array, which signals the importance of identifying this important variable when evaluating the tissue response of different device designs, and suggests that untethered or wireless devices may elicit less of a foreign body response.
authors.affiliation: The Keck Center for Tissue Engineering, Department of Bioengineering, College of Engineering, University of Utah, Salt Lake City, Utah 84112, USA.
authors.forename: Roy
authors.initials: R
authors.lastname: Biran
authors.forename: Dave C
authors.initials: DC
authors.lastname: Martin
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Tresco
mesh_terms: D000818:Animals; D001921:Brain / Q000166:cytology / Q000502:physiology* / Q000601:surgery*; D002452:Cell Count; D053331:Ectodysplasins / Q000378:metabolism; D004558:Electric Stimulation / Q000295:instrumentation / Q000379:methods; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D007150:Immunohistochemistry; D008264:Macrophages / Q000166:cytology; D008297:Male; D008422:Materials Testing; D008839:Microelectrodes; D009474:Neurons / Q000166:cytology; D019736:Prostheses and Implants; D051381:Rats; D012825:Silicon
chemical_list: D053331:Ectodysplasins; D005904:Glial Fibrillary Acidic Protein; D012825:Silicon