title: Biocompatibility and magnetic resonance imaging characteristics of carbon nanotube yarn neural electrodes in a rat model.
abstract: BACKGROUND
  Implantation of deep brain stimulation (DBS) electrodes is a landmark therapy for movement disorders and some mental conditions. Compared to conventional platinum-iridium (Pt-Ir) electrodes, carbon nanotube yarns (CNTY) electrodes have improved stability and interface characteristics with less distortion during high field strength MRI. Sprague-Dawley rat models were used to examine thein vivo histological and imaging properties of biocompatible CNTY throughout the subacute period.
  
  
  METHODS
  Sprague-Dawley rats received CNTY (n = 16) or Pt-Ir control (n = 16) electrodes. Behavioral markers, body weight, and survival were recorded. Comparative histology (HE, NeuN, CD68, and GFAP) was performed at 1, 6, and 12 weeks post-implantation; 3.0T MRI was performed at 1 and 12 weeks.
  
  
  RESULTS
  Of 32 rats, 30 (15 per group) survived implantation without reduced activity, paralysis, or incapacity to feed. Following implantation, progressive decreases in macrophage activation and neuron-depleted margins surrounding electrodes were observed in both groups. Inflammatory marker expression (CD68) was significantly lower in rats with implanted CNTY electrodes compared to controls at all time points. CNTY electrodes also caused less inflammation and shallower depths of macrophage penetration and neural disruption relative to the interface. Artifacts and distortion were observed on MRI of Pt-Ir but not CNTY electrodes.
  
  
  CONCLUSIONS
  CNTY electrodes exhibited reduced inflammatory margins compared to Pt-Ir electrodes throughout the subacute period, indicating reduced initial trauma, better overall biocompatibility, and reduced fibrous tissue formation. Coupled with less MRI distortion, CNTY electrodes may be useful alternatives when there is a need to monitor electrode placement by MRI.
authors.affiliation: Department of Neurosurgery, Peking Union Medical College Hospital, Beijing, China. pumcpumc@sina.com.
authors.forename: Yi
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Department of Neurosurgery, Peking Union Medical College Hospital, Beijing, China. duanwanru@163.com.|Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, China. duanwanru@163.com.|Department of Neurosurgery, Xuan Wu Hospital affiliated to Capital Medical University, Beijing, China. duanwanru@163.com.
authors.forename: Wanru
authors.initials: W
authors.lastname: Duan
authors.affiliation: Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, China. mcpumc@163.com.
authors.forename: Chao
authors.initials: C
authors.lastname: Ma
authors.affiliation: Institute of Man-Machine and Environmental Engineering, School of Aerospace, Tsinghua University, Beijing, China. jiangcq07@mails.tsinghua.edu.cn.
authors.forename: Changqing
authors.initials: C
authors.lastname: Jiang
authors.affiliation: Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, China. xieyk1938@yahoo.com.cn.
authors.forename: Yikuan
authors.initials: Y
authors.lastname: Xie
authors.affiliation: Institute of Man-Machine and Environmental Engineering, School of Aerospace, Tsinghua University, Beijing, China. haohw@tsinghua.edu.cn.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Hao
authors.affiliation: Department of Neurosurgery, Peking Union Medical College Hospital, Beijing, China. wangrz@126.com.
authors.forename: Renzhi
authors.initials: R
authors.lastname: Wang
authors.affiliation: Institute of Man-Machine and Environmental Engineering, School of Aerospace, Tsinghua University, Beijing, China. lilm@tsinghua.edu.cn.
authors.forename: Luming
authors.initials: L
authors.lastname: Li
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D001921:Brain / Q000166:cytology; D004567:Electrodes, Implanted / Q000009:adverse effects*; D008262:Macrophage Activation / Q000187:drug effects; D008279:Magnetic Resonance Imaging; D008422:Materials Testing; D037742:Nanotubes, Carbon / Q000009:adverse effects*; D009474:Neurons / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D037742:Nanotubes, Carbon