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ref: Winslow-2010.12 tags: date: 01-24-2013 21:58 gmt revision:4 [3] [2] [1] [0] [head]

PMID-20561678[0] A comparison of the tissue response to chronically implanted Parylene-C-coated and uncoated planar silicon microelectrode arrays in rat cortex.

  • Tested parylene-coated and uncoated silicon arrays.
  • "We did not find any difference in the relative intensity or the spatial distribution of neuronal or glial markers over the indwelling period [for the coated and uncoated electrodes]
  • "Parylene-C-coated substrates supported significantly less cell attachment, indicating that the foreign body response to planar silicon microelectrode arrays has little to do with the composition or decomposition of the silicon electrode.
  • Our quantitative comparison over the indwelling period does not support progressive increases in astrocyte encapsulation and/or progressive neuronal loss in the recording zone as dominant failure mechanisms of the type of chronic recording device.
  • Rather, they found that failure was associated with CD68 immunoreactivity, including demylenation of adjacent neurons and BBB breakdown (see also [1]) surrounding implanted electrodes at long indwelling times.
  • Further support: PMID-19963267[2]
    • While we found no evidence that reactive gliosis increases over time or that neuronal loss is progressive, we did find evidence of persistent inflammation and enhanced BBB permeability at the electrode brain tissue interface that extended over the 3 month indwelling period and that exhibited more animal to animal variability at 3 months than at 2 and 4 weeks.

____References____

[0] Winslow BD, Christensen MB, Yang WK, Solzbacher F, Tresco PA, A comparison of the tissue response to chronically implanted Parylene-C-coated and uncoated planar silicon microelectrode arrays in rat cortex.Biomaterials 31:35, 9163-72 (2010 Dec)
[1] COLLIAS JC, MANUELIDIS EE, Histopathological changes produced by implanted electrodes in cat brains; comparison with histopathological changes in human and experimental puncture wounds.J Neurosurg 14:3, 302-28 (1957 May)
[2] Winslow BD, Tresco PA, Quantitative analysis of the tissue response to chronically implanted microwire electrodes in rat cortex.Biomaterials 31:7, 1558-67 (2010 Mar)