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ref: -0 tags: bone marrow transplant chimera immune response to indwelling electrode implant capadona inflammation date: 02-02-2017 23:24 gmt revision:1 [0] [head]

PMID-24973296 The roles of blood-derived macrophages and resident microglia in the neuroinflammatory response to implanted intracortical microelectrodes.

  • Quite good introductory review on current understanding of immune / inflammatory / BBB breakdown response to indwelling neural implants.
  • Used chimera mice with marrow from CFP mice transplanted into irradiated hosts, so myeloid cells were labeled (including macrophages and monocytes).
    • Details of this process are properly fascinating ... there are clever ways of isolating and selecting the right marrow cells.
  • Implanted with a dummy Michigan style probe, 2mm x 123 um x 15um.
  • Histological processes and cell sorting / labeling also highly detailed.
  • 60% of the infiltrating cells (CFP+) are macrophages.
    • Within the total IBA1+ population (macrophages + microglia), we saw that only 20% of the total IBA1+ population was comprised of microglia at two weeks post implantation (Fig. 9G).
    • Additionally, at chronic time points (four, eight and sixteen weeks), we observed that less than 40% of the total IBA1+ population was comprised of microglia (Fig. 9G).
    • On the other hand, no significant differences were observed in microglia populations over time (Fig. 9G, Table 4). Together, our results suggest a predominant role of infiltrating macrophages surrounding implanted microelectrodes over time.
  • IBA1 = marker for ionized calcium binding adapter molecule, to label the total population of microglia/ macrophages (both resting and activated)
  • CD68 = activated microglia / macrophage.
    • Hard to discriminate microglia and infiltrating macrophages.
  • Interestingly, fluctuations in GFAP+ immunoreactivity correlated well with neuronal density and CFP+ immunoreactivty, suggesting a possible role of astrocytes in facilitating trafficking of blood-derived cells.
  • Contrary to what has been suggested by many intracortical microelectrode studies, a consistent connection was not found between activated microglia/macrophages and neuron density in our chimera models

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ref: -0 tags: L1 cell adhesion neural implants microglia DRG spinal cord dorsal root inflammation date: 11-19-2016 22:55 gmt revision:1 [0] [head]

PMID-22750248 In vivo effects of L1 coating on inflammation and neuronal health at the electrode-tissue interface in rat spinal cord and dorsal root ganglion.

  • Kolarcik CL1, Bourbeau D, Azemi E, Rost E, Zhang L, Lagenaur CF, Weber DJ, Cui XT.
  • Quote: With L1, neurofilament staining was significantly increased while neuronal cell death decreased.
  • These results indicate that L1-modified electrodes may result in an improved chronic neural interface and will be evaluated in recording and stimulation studies.
  • Ok, so this CAM seems to mitigate against microglia / inflammation, but how was it selected vs any of the other CAMs and surface proteins? (This domain is almost completely unknown by me..)
  • Ultimate strategy likely to be a broad combination of mechanical (size, flexibility), biochemical (inflammation, cell migration), electrochamical (surface coatings) and vasculature-avoiding approaches.

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ref: -0 tags: bone regrowth hyperelastic 3d print implant hydroxyapatite polycaptolactone date: 09-30-2016 18:27 gmt revision:0 [head]

Hyperelastic “bone”: A highly versatile, growth factor–free, osteoregenerative, scalable, and surgically friendly biomaterial

  • (From the abstract): hyperelastic “bone” is composed of 90 weight % (wt %) hydroxyapatite and 10 wt % polycaprolactone or poly(lactic-co-glycolic acid),
  • Can be rapidly three-dimensionally (3D) printed (up to 275 cm3/hour) from room temperature extruded liquid inks.
  • Mechanical properties: ~32 to 67% strain to failure, ~4 to 11 MPa elastic modulus & was highly absorbent (50% material porosity)
  • Supported cell viability and proliferation, and induced osteogenic differentiation of bone marrow–derived human mesenchymal stem cells cultured in vitro over 4 weeks without any osteo-inducing factors in the medium.
  • HB did not elicit a negative immune response, became vascularized, quickly integrated with surrounding tissues, and rapidly ossified and supported new bone growth without the need for added biological factors.

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ref: -0 tags: reactive oxygen accelerated aging neural implants date: 10-07-2015 18:45 gmt revision:1 [0] [head]

PMID-25627426 Rapid evaluation of the durability of cortical neural implants using accelerated aging with reactive oxygen species.

  • Takmakov P1, Ruda K, Scott Phillips K, Isayeva IS, Krauthamer V, Welle CG.
  • TDT W / PI implants completely failed (W etched and PI completely flaked off) after 1 week in 87C H2O2 / PBS solution. Not surprising.
    • In the Au plated W, the Au remained, the PI flaked off, while thin fragile gold tubes were left. Interesting.
  • Pt/Ii + Parylene-C microprobes seemed to fare better; one was unaffected, others experienced a drop in impedance.
  • NeuralNexus (Si3N4 insulated, probably, plus Ir recording pads) showed no change in H2O2 RAA, strong impedance drop (thicker oxide layer?)
  • Same for blackrock / utah probe (Parylene-C), though there the parylene peeled from the Si substrate a bit.

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ref: -2008 tags: tantalum chromium polyimide tungsten flexible neural implants adhesion layer date: 06-24-2015 22:53 gmt revision:2 [1] [0] [head]

PMID-18640155 Characterization of flexible ECoG electrode arrays for chronic recording in awake rats.

  • Yeager JD1, Phillips DJ, Rector DM, Bahr DF.
  • We tested several different adhesion techniques including the following: gold alone without an adhesion layer, titanium-tungsten, tantalum and chromium.
  • All films were DC magnetron sputtered, without breaking vacuum between the adhesion layer (5nm) and gold counductor layer (300nm).
  • We found titanium-tungsten to be a suitable adhesion layer considering the biocompatibility requirements as well as stability and delamination resistance.
  • While chromium and tantalum produced stronger gold adhesion, concerns over biocompatibility of these materials require further testing.
    • Thought: use tantalum directly, no Ti needed.
    • Much better than Cr -- much more ductile and biocompatible.
    • Caveat: studies showing reduction to stociometric Ta results in delamination.
  • Ta conductivity: 1.35e-7 Ohms * m; Ti 4.2e-7; 3x better (film can be 3x thinner..)

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ref: -0 tags: noise triboelectric implant BMI date: 05-16-2014 17:28 gmt revision:1 [0] [head]

source -- Durand

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ref: Stensaas-1976.01 tags: histology implant electrodes immune response date: 01-25-2013 02:52 gmt revision:1 [0] [head]

PMID-782142[0] The reaction of the cerebral cortex to chronically implanted plastic needles.

  • Three different classes of result:
    • Type I is characterized by little or no gliosis and synapses within 1-5mu of the implant;
    • type II contains a pronounced zone of reactive astrocytes;
    • type III is typified by a zone of connective tissue near the implant surface
      • One implant can evince all 3 different types!
  • Already were thinking of neuroprosthetic devices.

____References____

[0] Stensaas SS, Stensaas LJ, The reaction of the cerebral cortex to chronically implanted plastic needles.Acta Neuropathol 35:3, 187-203 (1976)

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ref: Harris-2011.12 tags: mechanically adaptive electrodes implants case western dissolving flexible histology Harris date: 01-25-2013 01:39 gmt revision:5 [4] [3] [2] [1] [0] [head]

PMID-22049097[0] Mechanically adaptive intracortical implants improve the proximity of neuronal cell bodies.

  • See also [1]
  • Initial tensile modulus of 5GPa dropped to 12MPa. (almost 500-fold!)
    • Their polymer nanocomposite (NC) still swells 65-70% (with water?)
    • Implant size 100 x 200um.
  • Controlled with tungsten of identical size and coating.
  • Tethered to skull.
  • Interesting:
    • The neuronal nuclei density within 100 µm of the device at four weeks post-implantation was greater for the compliant nanocomposite compared to the stiff wire.
    • At eight weeks post-implantation, the neuronal nuclei density around the nanocomposite was maintained, but the density around the wire recovered to match that of the nanocomposite.
    • Hypothesis, in discussion: softer implants are affecting the time-course of the response rather that final results
  • The glial scar response to the compliant nanocomposite was less vigorous than it was to the stiffer wire
  • Cultured astrocytes have been shown to respond to mechanical stimuli via calcium signaling (Ostrow and Sachs, 2005).
  • Substrate stiffness is also known to shift cell differentiation in mesenchymal stem cells to be neurogenic, myogenic, or osteogenic (Engler et al., 2006).
  • In vivo studies which focus on the effects of electrode tethering have shown that untethered implants reduce the extent of the glial scar (Biran et al., 2007; Kim et al., 2004; Subbaroyan, 2007)
  • Parylene, polymide, and PDMS still each have moduli 6 orders of mangitude larger than that of the brain.
  • In some of their plots, immune response is higher around the nanocomposites!
    • Could be that their implant is still too large / stiff?
  • Note that recent research shows that vitemin may have neuroprotective effects --
    • Research has linked vimentin expression to rapid neurite extension in response to damage (Levin et al., 2009)
    • NG2+ cells that express vimentin have been proposed to support repair of central nervous system (CNS) damage, and stabilize axons in response to dieback from ED1+ cells (Alonso, 2005; Nishiyama, 2007; Busch et al., 2010)
  • Prior work (Frampton et al., 2010 PMID-20336824[2]) hypothesizes that a more compact GFAP response increases the impedance of an electrode which may decrease the quality of electrode recordings.

____References____

[0] Harris JP, Capadona JR, Miller RH, Healy BC, Shanmuganathan K, Rowan SJ, Weder C, Tyler DJ, Mechanically adaptive intracortical implants improve the proximity of neuronal cell bodies.J Neural Eng 8:6, 066011 (2011 Dec)
[1] Harris JP, Hess AE, Rowan SJ, Weder C, Zorman CA, Tyler DJ, Capadona JR, In vivo deployment of mechanically adaptive nanocomposites for intracortical microelectrodes.J Neural Eng 8:4, 046010 (2011 Aug)
[2] Frampton JP, Hynd MR, Shuler ML, Shain W, Effects of glial cells on electrode impedance recorded from neuralprosthetic devices in vitro.Ann Biomed Eng 38:3, 1031-47 (2010 Mar)

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ref: -0 tags: saccarose sugar sweet electrode implantation force germany date: 01-24-2013 21:46 gmt revision:0 [head]

PMID-22254391 Chronic intracortical implantation of saccharose-coated flexible shaft electrodes into the cortex of rats.

  • measured forces of about 6mN inserting the 75um diameter saccharose-coated electrode.
    • Individual wires were 40um in diameter.
  • Limited longitudinal histology or electrophysiology

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ref: Biran-2005.09 tags: Tresco histology chronic implantation astrocytes microglia date: 01-04-2013 02:28 gmt revision:3 [2] [1] [0] [head]

PMID-16045910[0] Neuronal cell loss accompanies the brain tissue response to chronically implanted silicon microelectrode arrays.

  • We observed persistent ED1 immunoreactivity around implanted silicon microelectrode arrays implanted in adult rat cortex that was accompanied by a significant reduction in nerve fiber density and nerve cell bodies in the tissue immediately surrounding the implanted silicon microelectrode arrays.
  • We found that explanted electrodes were covered with ED1/MAC-1 immunoreactive cells and that the cells released MCP-1 and TNF-a under serum-free conditions in vitro.
  • See also [1] and [2]
  • Electrodes: Michigan type, 5mm long, 200um wide tapering to 30um, 15um thick at the shank tapering to 2um.
    • Show that the chronic response is markedly different than acute stab wounds.
    • "Stab wounds resulted in comparatively minimal neurofilament loss at 2 weeks (A) and no apparent loss by 4 weeks".
    • "The number of neuronal bodies is reduced in the area adjacent to microelectrodes (B, D) but appears unaltered surrounding stab wound lesions (A, C; lesion site in center of each image)."
  • Includes details of immunostaining, which could be useful.

____References____

[0] Biran R, Martin DC, Tresco PA, Neuronal cell loss accompanies the brain tissue response to chronically implanted silicon microelectrode arrays.Exp Neurol 195:1, 115-26 (2005 Sep)
[1] Szarowski DH, Andersen MD, Retterer S, Spence AJ, Isaacson M, Craighead HG, Turner JN, Shain W, Brain responses to micro-machined silicon devices.Brain Res 983:1-2, 23-35 (2003 Sep 5)
[2] Gilletti A, Muthuswamy J, Brain micromotion around implants in the rodent somatosensory cortex.J Neural Eng 3:3, 189-95 (2006 Sep)

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ref: -0 tags: Purdue magnetic bullet electrode implantation date: 01-04-2013 00:51 gmt revision:3 [2] [1] [0] [head]

PMID-19596378 Magnetic insertion system for flexible electrode implantation.

  • Probes constructed from a sharp magnetic tip attached to a flexible tether.
  • Cite Polikov et al 2005. {781}.
  • Re micromotion: (Gilletti and Muthuswamy, 2006 {1102}; Lee et al., 2004; Subbaroyan et al., 2005 {1103}).
  • 0.6 mm (600 um!) diameter steel bullet, 4mm long, on the end of 38 gauge magnet wire. Mass 7.2 +- 0.4 mg.
  • Peak current 520 A froman 800V, 900uF capacitor which produces a maximum force of 10 N on the electrode, driving it at 126.25 m/s.
  • Did manage to get neural data.
  • Experimental evidence suggests that macrophages have difficulty adhering to and spreading on polymer fibers ranging between 2.1 and 5.9 um in diameter. PMID-8902241 Bernatchez et al. 1996 and {746}.
  • Shot through the dura.
  • Also reference magnetic stereotaxis for use in manipulating magnetic 'seeds' through cancers for hyperthremic destruction.
  • See also their 2011 AES abstract

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ref: -0 tags: electrode implantation spring modeling muscles sewing date: 01-16-2012 17:30 gmt revision:0 [head]

PMID-21719340 Modelization of a self-opening peripheral neural interface: a feasibility study.

  • Electrode is self-opening, and they outline the math behind it. This could be useful!

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ref: Najafi-1986.12 tags: Najafi implantable wired recording Michigan array multiplexing silicon boron MEA date: 01-05-2012 03:07 gmt revision:8 [7] [6] [5] [4] [3] [2] [head]

IEEE-1052646 (pdf) An implantable multielectrode array with on-chip signal processing

  • "The major reason for the slow progress in the understanding of neural circuits has been the lack of adequate instrumentation."
  • previous photolithographic: [4],[5]. Their first publication: [7].
  • Kensall Wise, not Stephen.
  • Single shank
  • 10 recording sites spaced at 100um
  • Amplifying 100x, b/w 15kHz., multiplexing.
  • width: 15um near tip, 160um at base.
  • 3 leads (!) power, ground, data.
  • 6um LOCOS enhancement and depletion NMOS technology -- not CMOS. (latter is prone to latch-up)
  • 5mW power.
  • boron dope silicon, etch back non doped portion with ethylenediamine-pyrocatechol (EDP) water solution.
  • must not have any substrate bias!

____References____

Najafi, K. and Wise, K.D. An implantable multielectrode array with on-chip signal processing Solid-State Circuits, IEEE Journal of 21 6 1035 - 1044 (1986)

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ref: Lim-2009.09 tags: auditory midbrain implant deaf cochlea stimulation inferior colliculus date: 01-03-2012 06:55 gmt revision:2 [1] [0] [head]

PMID-19762428[0] Auditory midbrain implant: a review.

  • Inferior to a cochlear implant -- subjects, at the best, could understand speech only with lip-reading cues.
  • But! It's safe, and offers some degree of perception.
  • Also see: PMID-21157353[1]
    • Neurofibramatosis type 2 can also lead to cochlear deafness.
    • Implanted in the dorsal and ventral cochlear nuclei in the lateral recess of the IVth ventricle of the brain stem.
    • EABRs (evoked auditory brain stem responses); even though these were associated with electrodes in the right place, they could not be used for device fitting (?)

____References____

[0] Lim HH, Lenarz M, Lenarz T, Auditory midbrain implant: a review.Trends Amplif 13:3, 149-80 (2009 Sep)
[1] O'Driscoll M, El-Deredy W, Ramsden RT, Brain stem responses evoked by stimulation of the mature cochlear nucleus with an auditory brain stem implant.Ear Hear 32:3, 286-99 (2011 May-Jun)

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ref: bookmark-0 tags: Delgado Bulls microstimulation ICMS control implant date: 01-06-2008 18:05 gmt revision:2 [1] [0] [head]

http://www.biotele.com/Delgado.htm

  • stimulated the caudate to stop the charging bull.
  • interesting account of the later part of his life spent in Spain, when his popularity wained
  • Delgado still appears to have some quite radical tendencies, such as belief in the inexorable advance of technology, even if it is immoral/unethical.