OBJECTIVE: Microelectrodes implanted in the central nervous system (CNS) often fail in long term implants due to the immunological tissue response caused by tethering forces of the connecting wires. In addition to the tethering effect, there is a mechanical stress that occurs at the device-tissue interface simply because the microelectrode is a rigid body floating in soft tissue and it cannot reshape itself to comply with changes in the surrounding tissue. In the current study we evaluated the scar tissue formation to tetherless devices with two significantly different geometries in the rat brain and spinal cord in order to investigate the effects of device geometry. APPROACH: One of the implant geometries resembled the wireless, floating microstimulators that we are currently developing in our laboratory and the other was a (shank only) Michigan probe for comparison. Both electrodes were implanted into either the cervical spinal cord or the motor cortices, one on each side. MAIN RESULTS: The most pronounced astroglial and microglial reactions occurred within 20 μm from the device and decreased sharply at larger distances. Both cell types displayed the morphology of non-activated cells past the 100 μm perimeter. Even though the aspect ratios of the implants were different, the astroglial and microglial responses to both microelectrode types were very mild in the brain, stronger and yet limited in the spinal cord. SIGNIFICANCE: These observations confirm previous reports and further suggest that tethering may be responsible for most of the tissue response in chronic implants and that the electrode size has a smaller contribution with floating electrodes. The electrode size may be playing primarily an amplifying role to the tethering forces in the brain whereas the size itself may induce chronic response in the spinal cord where the movement of surrounding tissues is more significant.
OBJECTIVE: Microelectrodes implanted in the central nervous system (CNS) often fail in long term implants due to the immunological tissue response caused by tethering forces of the connecting wires. In addition to the tethering effect, there is a mechanical stress that occurs at the device-tissue interface simply because the microelectrode is a rigid body floating in soft tissue and it cannot reshape itself to comply with changes in the surrounding tissue. In the current study we evaluated the scar tissue formation to tetherless devices with two significantly different geometries in the rat brain and spinal cord in order to investigate the effects of device geometry. APPROACH: One of the implant geometries resembled the wireless, floating microstimulators that we are currently developing in our laboratory and the other was a (shank only) Michigan probe for comparison. Both electrodes were implanted into either the cervical spinal cord or the motor cortices, one on each side. MAIN RESULTS: The most pronounced astroglial and microglial reactions occurred within 20 μm from the device and decreased sharply at larger distances. Both cell types displayed the morphology of non-activated cells past the 100 μm perimeter. Even though the aspect ratios of the implants were different, the astroglial and microglial responses to both microelectrode types were very mild in the brain, stronger and yet limited in the spinal cord. SIGNIFICANCE: These observations confirm previous reports and further suggest that tethering may be responsible for most of the tissue response in chronic implants and that the electrode size has a smaller contribution with floating electrodes. The electrode size may be playing primarily an amplifying role to the tethering forces in the brain whereas the size itself may induce chronic response in the spinal cord where the movement of surrounding tissues is more significant.
Authors: David Borton; Marco Bonizzato; Janine Beauparlant; Jack DiGiovanna; Eduardo M Moraud; Nikolaus Wenger; Pavel Musienko; Ivan R Minev; Stéphanie P Lacour; José del R Millán; Silvestro Micera; Grégoire Courtine Journal: Neurosci Res Date: 2013-10-14 Impact factor: 3.304
Authors: David J Guggenmos; Meysam Azin; Scott Barbay; Jonathan D Mahnken; Caleb Dunham; Pedram Mohseni; Randolph J Nudo Journal: Proc Natl Acad Sci U S A Date: 2013-12-09 Impact factor: 11.205
Authors: Katherine N Gibson-Corley; Oliver Flouty; Hiroyuki Oya; George T Gillies; Matthew A Howard Journal: Biomed Res Int Date: 2014-04-01 Impact factor: 3.411
Authors: Steven M Wellman; James R Eles; Kip A Ludwig; John P Seymour; Nicholas J Michelson; William E McFadden; Alberto L Vazquez; Takashi D Y Kozai Journal: Adv Funct Mater Date: 2017-07-19 Impact factor: 18.808
Authors: Paras R Patel; Huanan Zhang; Matthew T Robbins; Justin B Nofar; Shaun P Marshall; Michael J Kobylarek; Takashi D Y Kozai; Nicholas A Kotov; Cynthia A Chestek Journal: J Neural Eng Date: 2016-10-05 Impact factor: 5.379
Authors: Christi L Kolarcik; Carlos A Castro; Andrew Lesniak; Anthony J Demetris; Lee E Fisher; Robert A Gaunt; Douglas J Weber; X Tracy Cui Journal: J Neural Eng Date: 2020-07-10 Impact factor: 5.379
Authors: I Mitch Taylor; Zhanhong Du; Emma T Bigelow; James R Eles; Anthony R Horner; Kasey A Catt; Stephen G Weber; Brian G Jamieson; X Tracy Cui Journal: J Mater Chem B Date: 2017-03-06 Impact factor: 6.331
Authors: Daniel K Freeman; Jonathan M O'Brien; Parshant Kumar; Brian Daniels; Reed A Irion; Louis Shraytah; Brett K Ingersoll; Andrew P Magyar; Andrew Czarnecki; Jesse Wheeler; Jonathan R Coppeta; Michael P Abban; Ronald Gatzke; Shelley I Fried; Seung Woo Lee; Amy E Duwel; Jonathan J Bernstein; Alik S Widge; Ana Hernandez-Reynoso; Aswini Kanneganti; Mario I Romero-Ortega; Stuart F Cogan Journal: Front Neurosci Date: 2017-11-27 Impact factor: 4.677