1
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Boltcreed E, Ersöz A, Han M, McConnell GC. Short-Term Effects of Gamma Stimulation on Neuroinflammation at the Tissue-Electrode Interface in Motor Cortex. Neuromodulation 2024; 27:500-508. [PMID: 38099883 PMCID: PMC10990794 DOI: 10.1016/j.neurom.2023.11.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 10/20/2023] [Accepted: 11/07/2023] [Indexed: 04/05/2024]
Abstract
OBJECTIVES The reliability of long-term neural recordings as therapeutic interventions for motor and sensory disorders is hampered by the brain tissue response. Previous work showed that flickering light at gamma frequencies (ie, 20-50 Hz) causes enhanced microglial recruitment in the visual cortex. The effects of gamma stimulation on glial cells surrounding implanted neural electrodes are not well understood. We hypothesized that invasive stimulation in the gamma frequency band increases microglial recruitment in the short term and reduces astrogliosis at the tissue-electrode interface. MATERIALS AND METHODS Male Long Evans rats were implanted with dual-shank silicon microelectrode arrays into the motor cortex. After implantation, rats received one hour of 40-Hz stimulation at a constant current of 10 μA using charge-balanced, biphasic pulses on one shank, and the other shank served as the nonstimulated control. Postmortem, tissue sections were stained with ectodermal dysplasia 1 (ED1) for activated microglia, glial fibrillary acidic protein (GFAP) for astrocytes, and 4',6-diamidino-2-phenylindole (DAPI) for nonspecific nuclei. Fluorescent intensity and cell number as a function of distance from the tissue-electrode interface were used to quantify all stained sections. RESULTS Fluorescent intensity for ED1 was nearly 40% lower for control than for stimulated sites (0-500 μm away from the implant), indicating increased microglial recruitment to the stimulated site (p < 0.05). Fluorescent intensity for GFAP was >67% higher for control than for stimulated sites (0-500 μm away from the implant), indicating reduced astrogliosis at the stimulated site (p < 0.05). No differences were observed in DAPI-stained sections between conditions. CONCLUSIONS These results suggest that short-term gamma stimulation modulates glial recruitment in the immediate vicinity of the microelectrode. Future studies will investigate the long-term effects of gamma stimulation on glial recruitment at the tissue-electrode interface as a strategy to improve long-term recording reliability.
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Affiliation(s)
- Emily Boltcreed
- Stevens Institute of Technology, Hoboken, NJ; Semcer Center for Healthcare Innovation, Hoboken, NJ
| | - Alpaslan Ersöz
- Mechanical Engineering Department, Carnegie Mellon University, Pittsburgh, PA; Department of Biomedical Engineering, University of Connecticut, Storrs, CT
| | - Martin Han
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT
| | - George C McConnell
- Stevens Institute of Technology, Hoboken, NJ; Semcer Center for Healthcare Innovation, Hoboken, NJ.
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2
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Shan Y, Cui X, Chen X, Li Z. Recent progress of electroactive interface in neural engineering. WILEY INTERDISCIPLINARY REVIEWS. NANOMEDICINE AND NANOBIOTECHNOLOGY 2023; 15:e01827. [PMID: 35715994 DOI: 10.1002/wnan.1827] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 05/23/2022] [Accepted: 05/24/2022] [Indexed: 01/31/2023]
Abstract
Neural tissue is an electrical responsible organ. The electricity plays a vital role in the growth and development of nerve tissue, as well as the repairing after diseases. The interface between the nervous system and external device for information transmission is called neural electroactive interface. With the development of new materials and fabrication technologies, more and more new types of neural interfaces are developed and the interfaces can play crucial roles in treating many debilitating diseases such as paralysis, blindness, deafness, epilepsy, and Parkinson's disease. Neural interfaces are developing toward flexibility, miniaturization, biocompatibility, and multifunctionality. This review presents the development of neural electrodes in terms of different materials for constructing electroactive neural interfaces, especially focus on the piezoelectric materials-based indirect neuromodulation due to their features of wireless control, excellent effect, and good biocompatibility. We discussed the challenges we need to consider before the application of these new interfaces in clinical practice. The perspectives about future directions for developing more practical electroactive interface in neural engineering are also discussed in this review. This article is categorized under: Implantable Materials and Surgical Technologies > Nanomaterials and Implants Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement.
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Affiliation(s)
- Yizhu Shan
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, China.,School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Xi Cui
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, China.,School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Xun Chen
- Department of Electronic Engineering and Information Science, University of Science and Technology of China, Hefei, Anhui, China
| | - Zhou Li
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, China.,School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, China.,Center of Nanoenergy Research, School of Physical Science and Technology, Guangxi University, Nanning, China.,Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, China
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3
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Girão AF, Serrano MC, Completo A, Marques PAAP. Is Graphene Shortening the Path toward Spinal Cord Regeneration? ACS NANO 2022; 16:13430-13467. [PMID: 36000717 PMCID: PMC9776589 DOI: 10.1021/acsnano.2c04756] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Along with the development of the next generation of biomedical platforms, the inclusion of graphene-based materials (GBMs) into therapeutics for spinal cord injury (SCI) has potential to nourish topmost neuroprotective and neuroregenerative strategies for enhancing neural structural and physiological recovery. In the context of SCI, contemplated as one of the most convoluted challenges of modern medicine, this review first provides an overview of its characteristics and pathophysiological features. Then, the most relevant ongoing clinical trials targeting SCI, including pharmaceutical, robotics/neuromodulation, and scaffolding approaches, are introduced and discussed in sequence with the most important insights brought by GBMs into each particular topic. The current role of these nanomaterials on restoring the spinal cord microenvironment after injury is critically contextualized, while proposing future concepts and desirable outputs for graphene-based technologies aiming to reach clinical significance for SCI.
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Affiliation(s)
- André F. Girão
- Centre
for Mechanical Technology and Automation (TEMA), Department of Mechanical
Engineering, University of Aveiro (UA), Aveiro, 3810-193, Portugal
- Instituto
de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Calle Sor Juana Inés de la
Cruz 3, Madrid, 28049, Spain
- (A.F.G.)
| | - María Concepcion Serrano
- Instituto
de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Calle Sor Juana Inés de la
Cruz 3, Madrid, 28049, Spain
- (M.C.S.)
| | - António Completo
- Centre
for Mechanical Technology and Automation (TEMA), Department of Mechanical
Engineering, University of Aveiro (UA), Aveiro, 3810-193, Portugal
| | - Paula A. A. P. Marques
- Centre
for Mechanical Technology and Automation (TEMA), Department of Mechanical
Engineering, University of Aveiro (UA), Aveiro, 3810-193, Portugal
- (P.A.A.P.M.)
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4
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Ward S, Riley C, Carey EM, Nguyen J, Esener S, Nimmerjahn A, Sirbuly DJ. Electro-optical mechanically flexible coaxial microprobes for minimally invasive interfacing with intrinsic neural circuits. Nat Commun 2022; 13:3286. [PMID: 35672294 PMCID: PMC9174211 DOI: 10.1038/s41467-022-30275-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 04/22/2022] [Indexed: 12/17/2022] Open
Abstract
Central to advancing our understanding of neural circuits is developing minimally invasive, multi-modal interfaces capable of simultaneously recording and modulating neural activity. Recent devices have focused on matching the mechanical compliance of tissue to reduce inflammatory responses. However, reductions in the size of multi-modal interfaces are needed to further improve biocompatibility and long-term recording capabilities. Here a multi-modal coaxial microprobe design with a minimally invasive footprint (8-14 µm diameter over millimeter lengths) that enables efficient electrical and optical interrogation of neural networks is presented. In the brain, the probes allowed robust electrical measurement and optogenetic stimulation. Scalable fabrication strategies can be used with various electrical and optical materials, making the probes highly customizable to experimental requirements, including length, diameter, and mechanical properties. Given their negligible inflammatory response, these probes promise to enable a new generation of readily tunable multi-modal devices for long-term, minimally invasive interfacing with neural circuits.
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Affiliation(s)
- Spencer Ward
- Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Conor Riley
- Department of Nanoengineering, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Erin M Carey
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
| | - Jenny Nguyen
- Department of Nanoengineering, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Sadik Esener
- Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, CA, 92093, USA
- Department of Nanoengineering, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Axel Nimmerjahn
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, La Jolla, CA, 92037, USA.
| | - Donald J Sirbuly
- Department of Nanoengineering, University of California, San Diego, La Jolla, CA, 92093, USA.
- Materials Science and Engineering, University of California, San Diego, La Jolla, CA, 92093, USA.
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5
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Peña JS, Vazquez M. Harnessing the Neuroprotective Behaviors of Müller Glia for Retinal Repair. FRONT BIOSCI-LANDMRK 2022; 27:169. [PMID: 35748245 PMCID: PMC9639582 DOI: 10.31083/j.fbl2706169] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 04/18/2022] [Accepted: 05/05/2022] [Indexed: 11/29/2022]
Abstract
Progressive and irreversible vision loss in mature and aging adults creates a health and economic burden, worldwide. Despite the advancements of many contemporary therapies to restore vision, few approaches have considered the innate benefits of gliosis, the endogenous processes of retinal repair that precede vision loss. Retinal gliosis is fundamentally driven by Müller glia (MG) and is characterized by three primary cellular mechanisms: hypertrophy, proliferation, and migration. In early stages of gliosis, these processes have neuroprotective potential to halt the progression of disease and encourage synaptic activity among neurons. Later stages, however, can lead to glial scarring, which is a hallmark of disease progression and blindness. As a result, the neuroprotective abilities of MG have remained incompletely explored and poorly integrated into current treatment regimens. Bioengineering studies of the intrinsic behaviors of MG hold promise to exploit glial reparative ability, while repressing neuro-disruptive MG responses. In particular, recent in vitro systems have become primary models to analyze individual gliotic processes and provide a stepping stone for in vivo strategies. This review highlights recent studies of MG gliosis seeking to harness MG neuroprotective ability for regeneration using contemporary biotechnologies. We emphasize the importance of studying gliosis as a reparative mechanism, rather than disregarding it as an unfortunate clinical prognosis in diseased retina.
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Affiliation(s)
- Juan S. Peña
- Department of Biomedical Engineering, Rutgers, The State
University of New Jersey, Piscataway (08854), New Jersey, USA
| | - Maribel Vazquez
- Department of Biomedical Engineering, Rutgers, The State
University of New Jersey, Piscataway (08854), New Jersey, USA
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6
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Narcisse D, Mustafi SM, Carlson M, Kim S, Batabyal S, Wright W, Mohanty SK. Monitoring Visual Cortical Activities During Progressive Retinal Degeneration Using Functional Bioluminescence Imaging. Front Neurosci 2021; 15:750684. [PMID: 34690687 PMCID: PMC8530108 DOI: 10.3389/fnins.2021.750684] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 09/06/2021] [Indexed: 11/13/2022] Open
Abstract
Mouse models of inherited retinal degenerative diseases such as retinitis pigmentosa are characterized by degeneration of photoreceptors, which hinders the generation of signal to be transmitted to the visual cortex. By monitoring Ca2+-bioluminescence neural activity, we quantified changes in visual cortical activities in response to visual stimuli in RD10 mice during progression of retinal degeneration, which correlated with progressive deteriorations of electro-retinography signal from the eyes. The number of active neurons in the visual cortex, the intensity of Ca2+-bioluminescence response, and neural activation parameter showed progressive deterioration during aging. Further, we correlated the thinning of retina as measured by Optical Coherence Tomography with the decrease in visual cortical activities as retinal degeneration progressed. The present study establishes Ca2+-bioluminescence monitoring as a longitudinal imaging modality to characterize activities in visual cortex of retinal degenerative disease models and therapeutic interventions.
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Affiliation(s)
| | | | | | - Sanghoon Kim
- Nanoscope Technologies LLC, Bedford, TX, United States
| | | | - Weldon Wright
- Nanoscope Technologies LLC, Bedford, TX, United States
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7
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Yin P, Liu Y, Xiao L, Zhang C. Advanced Metallic and Polymeric Coatings for Neural Interfacing: Structures, Properties and Tissue Responses. Polymers (Basel) 2021; 13:2834. [PMID: 34451372 PMCID: PMC8401399 DOI: 10.3390/polym13162834] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/15/2021] [Accepted: 08/17/2021] [Indexed: 02/07/2023] Open
Abstract
Neural electrodes are essential for nerve signal recording, neurostimulation, neuroprosthetics and neuroregeneration, which are critical for the advancement of brain science and the establishment of the next-generation brain-electronic interface, central nerve system therapeutics and artificial intelligence. However, the existing neural electrodes suffer from drawbacks such as foreign body responses, low sensitivity and limited functionalities. In order to overcome the drawbacks, efforts have been made to create new constructions and configurations of neural electrodes from soft materials, but it is also more practical and economic to improve the functionalities of the existing neural electrodes via surface coatings. In this article, recently reported surface coatings for neural electrodes are carefully categorized and analyzed. The coatings are classified into different categories based on their chemical compositions, i.e., metals, metal oxides, carbons, conducting polymers and hydrogels. The characteristic microstructures, electrochemical properties and fabrication methods of the coatings are comprehensively presented, and their structure-property correlations are discussed. Special focus is given to the biocompatibilities of the coatings, including their foreign-body response, cell affinity, and long-term stability during implantation. This review article can provide useful and sophisticated insights into the functional design, material selection and structural configuration for the next-generation multifunctional coatings of neural electrodes.
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Affiliation(s)
| | - Yang Liu
- Department of Biomedical Engineering, Sun Yat-sen University, Shenzhen 518107, China; (P.Y.); (L.X.)
| | | | - Chao Zhang
- Department of Biomedical Engineering, Sun Yat-sen University, Shenzhen 518107, China; (P.Y.); (L.X.)
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8
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Interaction of micropatterned topographical and biochemical cues to direct neurite growth from spiral ganglion neurons. Hear Res 2021; 409:108315. [PMID: 34343850 DOI: 10.1016/j.heares.2021.108315] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 05/07/2021] [Accepted: 07/12/2021] [Indexed: 01/01/2023]
Abstract
Functional outcomes with neural prosthetic devices, such as cochlear implants, are limited in part due to physical separation between the stimulating elements and the neurons they stimulate. One strategy to close this gap aims to precisely guide neurite regeneration to position the neurites in closer proximity to electrode arrays. Here, we explore the ability of micropatterned biochemical and topographic guidance cues, singly and in combination, to direct the growth of spiral ganglion neuron (SGN) neurites, the neurons targeted by cochlear implants. Photopolymerization of methacrylate monomers was used to form unidirectional topographical features of ridges and grooves in addition to multidirectional patterns with 90o angle turns. Microcontact printing was also used to create similar uni- and multi-directional patterns of peptides on polymer surfaces. Biochemical cues included peptides that facilitate (laminin, LN) or repel (EphA4-Fc) neurite growth. On flat surfaces, SGN neurites preferentially grew on LN-coated stripes and avoided EphA4-Fc-coated stripes. LN or EphA4-Fc was selectively adsorbed onto the ridges or grooves to test the neurite response to a combination of topographical and biochemical cues. Coating the ridges with EphA4-Fc and grooves with LN lead to enhanced SGN alignment to topographical patterns. Conversely, EphA4-Fc coating on the grooves or LN coating on the ridges tended to disrupt alignment to topographical patterns. SGN neurites respond to combinations of topographical and biochemical cues and surface patterning that leverages both cues enhance guided neurite growth.
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9
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Gori M, Vadalà G, Giannitelli SM, Denaro V, Di Pino G. Biomedical and Tissue Engineering Strategies to Control Foreign Body Reaction to Invasive Neural Electrodes. Front Bioeng Biotechnol 2021; 9:659033. [PMID: 34113605 PMCID: PMC8185207 DOI: 10.3389/fbioe.2021.659033] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 04/27/2021] [Indexed: 12/21/2022] Open
Abstract
Neural-interfaced prostheses aim to restore sensorimotor limb functions in amputees. They rely on bidirectional neural interfaces, which represent the communication bridge between nervous system and neuroprosthetic device by controlling its movements and evoking sensory feedback. Compared to extraneural electrodes (i.e., epineural and perineural implants), intraneural electrodes, implanted within peripheral nerves, have higher selectivity and specificity of neural signal recording and nerve stimulation. However, being implanted in the nerve, their main limitation is represented by the significant inflammatory response that the body mounts around the probe, known as Foreign Body Reaction (FBR), which may hinder their rapid clinical translation. Furthermore, the mechanical mismatch between the consistency of the device and the surrounding neural tissue may contribute to exacerbate the inflammatory state. The FBR is a non-specific reaction of the host immune system to a foreign material. It is characterized by an early inflammatory phase eventually leading to the formation of a fibrotic capsule around intraneural interfaces, which increases the electrical impedance over time and reduces the chronic interface biocompatibility and functionality. Thus, the future in the reduction and control of the FBR relies on innovative biomedical strategies for the fabrication of next-generation neural interfaces, such as the development of more suitable designs of the device with smaller size, appropriate stiffness and novel conductive and biomimetic coatings for improving their long-term stability and performance. Here, we present and critically discuss the latest biomedical approaches from material chemistry and tissue engineering for controlling and mitigating the FBR in chronic neural implants.
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Affiliation(s)
- Manuele Gori
- Laboratory for Regenerative Orthopaedics, Department of Orthopaedic Surgery and Traumatology, Università Campus Bio-Medico di Roma, Rome, Italy
- Institute of Biochemistry and Cell Biology (IBBC) - National Research Council (CNR), Rome, Italy
| | - Gianluca Vadalà
- Laboratory for Regenerative Orthopaedics, Department of Orthopaedic Surgery and Traumatology, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Sara Maria Giannitelli
- Laboratory of Tissue Engineering, Department of Engineering, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Vincenzo Denaro
- Laboratory for Regenerative Orthopaedics, Department of Orthopaedic Surgery and Traumatology, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Giovanni Di Pino
- NeXT: Neurophysiology and Neuroengineering of Human-Technology Interaction Research Unit, Università Campus Bio-Medico di Roma, Rome, Italy
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10
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Dryg I, Xie Y, Bergmann M, Urban G, Shain W, Hofmann UG. Long-term in vivomonitoring of gliotic sheathing of ultrathin entropic coated brain microprobes with fiber-based optical coherence tomography. J Neural Eng 2021; 18. [PMID: 33657543 DOI: 10.1088/1741-2552/abebc2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 03/03/2021] [Indexed: 11/11/2022]
Abstract
Objective.Microfabricated neuroprosthetic devices have made possible important observations on neuron activity; however, long-term high-fidelity recording performance of these devices has yet to be realized. Tissue-device interactions appear to be a primary source of lost recording performance. The current state of the art for visualizing the tissue response surrounding brain implants in animals is immunohistochemistry + confocal microscopy, which is mainly performed after sacrificing the animal. Monitoring the tissue response as it develops could reveal important features of the response which may inform improvements in electrode design.Approach.Optical coherence tomography (OCT), an imaging technique commonly used in ophthalmology, has already been adapted for imaging of brain tissue. Here, we use OCT to achieve real-time,in vivomonitoring of the tissue response surrounding chronically implanted neural devices. The employed tissue-response-provoking implants are coated with a plasma-deposited nanofilm, which has been demonstrated as a biocompatible and anti-inflammatory interface for indwelling devices. We evaluate the method by comparing the OCT results to traditional histology qualitatively and quantitatively.Main results.The differences in OCT signal across the implantation period between the plasma group and the control reveal that the plasma-type coating of otherwise rigid brain probes (glass) only slightly improve the glial encapsulation in the brain parenchyma indicating that geometrical or mechanical influences are dominating the encapsulation process.Significance.Our approach can long-term monitor and compare the tissue-response to chronically-implanted neural probes with and withour plasma coating in living animal models. Our findings provide valuable insigh to the well acknowledged yet not solved challenge.
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Affiliation(s)
- Ian Dryg
- Department of Bioengineering, University of Washington, Seattle, WA, United States of America.,Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States of America
| | - Yijing Xie
- Section for Neuroelectronic Systems, Department of Neurosurgery, Medical Center, University of Freiburg, Freiburg, Germany
| | - Michael Bergmann
- Department of Microsystems Engineering (IMTEK), University of Freiburg, Freiburg, Germany
| | - Gerald Urban
- Department of Microsystems Engineering (IMTEK), University of Freiburg, Freiburg, Germany
| | - William Shain
- Department of Bioengineering, University of Washington, Seattle, WA, United States of America.,Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States of America
| | - Ulrich G Hofmann
- Section for Neuroelectronic Systems, Department of Neurosurgery, Medical Center, University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany
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11
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Forro C, Caron D, Angotzi GN, Gallo V, Berdondini L, Santoro F, Palazzolo G, Panuccio G. Electrophysiology Read-Out Tools for Brain-on-Chip Biotechnology. MICROMACHINES 2021; 12:124. [PMID: 33498905 PMCID: PMC7912435 DOI: 10.3390/mi12020124] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/18/2021] [Accepted: 01/19/2021] [Indexed: 02/07/2023]
Abstract
Brain-on-Chip (BoC) biotechnology is emerging as a promising tool for biomedical and pharmaceutical research applied to the neurosciences. At the convergence between lab-on-chip and cell biology, BoC couples in vitro three-dimensional brain-like systems to an engineered microfluidics platform designed to provide an in vivo-like extrinsic microenvironment with the aim of replicating tissue- or organ-level physiological functions. BoC therefore offers the advantage of an in vitro reproduction of brain structures that is more faithful to the native correlate than what is obtained with conventional cell culture techniques. As brain function ultimately results in the generation of electrical signals, electrophysiology techniques are paramount for studying brain activity in health and disease. However, as BoC is still in its infancy, the availability of combined BoC-electrophysiology platforms is still limited. Here, we summarize the available biological substrates for BoC, starting with a historical perspective. We then describe the available tools enabling BoC electrophysiology studies, detailing their fabrication process and technical features, along with their advantages and limitations. We discuss the current and future applications of BoC electrophysiology, also expanding to complementary approaches. We conclude with an evaluation of the potential translational applications and prospective technology developments.
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Affiliation(s)
- Csaba Forro
- Tissue Electronics, Fondazione Istituto Italiano di Tecnologia, Largo Barsanti e Matteucci, 53-80125 Naples, Italy; (C.F.); (F.S.)
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA
| | - Davide Caron
- Enhanced Regenerative Medicine, Fondazione Istituto Italiano di Tecnologia, Via Morego, 30-16163 Genova, Italy; (D.C.); (V.G.)
| | - Gian Nicola Angotzi
- Microtechnology for Neuroelectronics, Fondazione Istituto Italiano di Tecnologia, Via Morego, 30-16163 Genova, Italy; (G.N.A.); (L.B.)
| | - Vincenzo Gallo
- Enhanced Regenerative Medicine, Fondazione Istituto Italiano di Tecnologia, Via Morego, 30-16163 Genova, Italy; (D.C.); (V.G.)
| | - Luca Berdondini
- Microtechnology for Neuroelectronics, Fondazione Istituto Italiano di Tecnologia, Via Morego, 30-16163 Genova, Italy; (G.N.A.); (L.B.)
| | - Francesca Santoro
- Tissue Electronics, Fondazione Istituto Italiano di Tecnologia, Largo Barsanti e Matteucci, 53-80125 Naples, Italy; (C.F.); (F.S.)
| | - Gemma Palazzolo
- Enhanced Regenerative Medicine, Fondazione Istituto Italiano di Tecnologia, Via Morego, 30-16163 Genova, Italy; (D.C.); (V.G.)
| | - Gabriella Panuccio
- Enhanced Regenerative Medicine, Fondazione Istituto Italiano di Tecnologia, Via Morego, 30-16163 Genova, Italy; (D.C.); (V.G.)
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12
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Pflüger P, Pinnell RC, Martini N, Hofmann UG. Chronically Implanted Microelectrodes Cause c-fos Expression Along Their Trajectory. Front Neurosci 2020; 13:1367. [PMID: 31998057 PMCID: PMC6965008 DOI: 10.3389/fnins.2019.01367] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 12/03/2019] [Indexed: 01/05/2023] Open
Abstract
When designing electrodes and probes for brain–machine interfaces, one of the challenges faced involves minimizing the brain-tissue response, which would otherwise create an environment that is detrimental for the accurate functioning of such probes. Following the implantation process, the brain reacts with a sterile inflammation response and resulting astrocytic glial scar formation, potentially resulting in neuronal cell loss around the implantation site. Such alterations in the naïve brain tissue can hinder both the quality of neuronal recordings, and the efficacy of deep-brain stimulation. In this study, we chronically implanted a glass-supported polyimide microelectrode in the dorsolateral striatum of Sprague–Dawley rats. The effect of high-frequency stimulation (HFS) was investigated using c-fos immunoreactivity techniques. GFAP and ED1 immunohistochemistry were used to analyze the brain-tissue response. No changes in c-fos expression were found for either the acute or chronic stimulus groups; although a c-fos expression was found along the length of the implantation trajectory, following chronic implantation of our stiffened polyimide microelectrode. Furthermore, we also observed the formation of a glial scar around the microelectrode, with an accompanying low number of inflammation cells. Histological and statistical analysis of NeuN-positive cells did not demonstrate a pronounced “kill zone” with accompanying neuronal cell death around the implantation site, neither on the polymer side, nor on the glass side of the PI-glass probe.
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Affiliation(s)
- Patrick Pflüger
- Section for Neuroelectronic Systems, Clinic for Neurosurgery, Medical Center - University of Freiburg, University of Freiburg, Freiburg im Breisgau, Germany.,Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
| | - Richard C Pinnell
- Section for Neuroelectronic Systems, Clinic for Neurosurgery, Medical Center - University of Freiburg, University of Freiburg, Freiburg im Breisgau, Germany.,Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
| | - Nadja Martini
- Section for Neuroelectronic Systems, Clinic for Neurosurgery, Medical Center - University of Freiburg, University of Freiburg, Freiburg im Breisgau, Germany.,Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
| | - Ulrich G Hofmann
- Section for Neuroelectronic Systems, Clinic for Neurosurgery, Medical Center - University of Freiburg, University of Freiburg, Freiburg im Breisgau, Germany.,Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
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13
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Sung C, Jeon W, Nam KS, Kim Y, Butt H, Park S. Multimaterial and multifunctional neural interfaces: from surface-type and implantable electrodes to fiber-based devices. J Mater Chem B 2020; 8:6624-6666. [DOI: 10.1039/d0tb00872a] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Development of neural interfaces from surface electrodes to fibers with various type, functionality, and materials.
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Affiliation(s)
- Changhoon Sung
- Department of Bio and Brain Engineering
- Korea Advanced Institute of Science and Technology (KAIST)
- Daejeon 34141
- Republic of Korea
| | - Woojin Jeon
- Department of Bio and Brain Engineering
- Korea Advanced Institute of Science and Technology (KAIST)
- Daejeon 34141
- Republic of Korea
| | - Kum Seok Nam
- School of Electrical Engineering
- Korea Advanced Institute of Science and Technology (KAIST)
- Daejeon 34141
- Republic of Korea
| | - Yeji Kim
- Department of Bio and Brain Engineering
- Korea Advanced Institute of Science and Technology (KAIST)
- Daejeon 34141
- Republic of Korea
| | - Haider Butt
- Department of Mechanical Engineering
- Khalifa University
- Abu Dhabi 127788
- United Arab Emirates
| | - Seongjun Park
- Department of Bio and Brain Engineering
- Korea Advanced Institute of Science and Technology (KAIST)
- Daejeon 34141
- Republic of Korea
- KAIST Institute for Health Science and Technology (KIHST)
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14
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Singh RK, Occelli LM, Binette F, Petersen-Jones SM, Nasonkin IO. Transplantation of Human Embryonic Stem Cell-Derived Retinal Tissue in the Subretinal Space of the Cat Eye. Stem Cells Dev 2019; 28:1151-1166. [PMID: 31210100 PMCID: PMC6708274 DOI: 10.1089/scd.2019.0090] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
To develop biological approaches to restore vision, we developed a method of transplanting stem cell-derived retinal tissue into the subretinal space of a large-eye animal model (cat). Human embryonic stem cells (hESC) were differentiated to retinal organoids in a dish. hESC-derived retinal tissue was introduced into the subretinal space of wild-type cats following a pars plana vitrectomy. The cats were systemically immunosuppressed with either prednisolone or prednisolone plus cyclosporine A. The eyes were examined by fundoscopy and spectral-domain optical coherence tomography imaging for adverse effects due to the presence of the subretinal grafts. Immunohistochemistry was done with antibodies to retinal and human markers to delineate graft survival, differentiation, and integration into cat retina. We successfully delivered hESC-derived retinal tissue into the subretinal space of the cat eye. We observed strong infiltration of immune cells in the graft and surrounding tissue in the cats treated with prednisolone. In contrast, we showed better survival and low immune response to the graft in cats treated with prednisolone plus cyclosporine A. Immunohistochemistry with antibodies (STEM121, CALB2, DCX, and SMI-312) revealed large number of graft-derived fibers connecting the graft and the host. We also show presence of human-specific synaptophysin puncta in the cat retina. This work demonstrates feasibility of engrafting hESC-derived retinal tissue into the subretinal space of large-eye animal models. Transplanting retinal tissue in degenerating cat retina will enable rapid development of preclinical in vivo work focused on vision restoration.
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Affiliation(s)
- Ratnesh K Singh
- Lineage Cell Therapeutics, Inc. (formerly BioTime Inc.), Carlsbad, California
| | - Laurence M Occelli
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lasing, Michigan
| | - Francois Binette
- Lineage Cell Therapeutics, Inc. (formerly BioTime Inc.), Carlsbad, California
| | - Simon M Petersen-Jones
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lasing, Michigan
| | - Igor O Nasonkin
- Lineage Cell Therapeutics, Inc. (formerly BioTime Inc.), Carlsbad, California
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15
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Milekovic T, Bacher D, Sarma AA, Simeral JD, Saab J, Pandarinath C, Yvert B, Sorice BL, Blabe C, Oakley EM, Tringale KR, Eskandar E, Cash SS, Shenoy KV, Henderson JM, Hochberg LR, Donoghue JP. Volitional control of single-electrode high gamma local field potentials by people with paralysis. J Neurophysiol 2019; 121:1428-1450. [PMID: 30785814 DOI: 10.1152/jn.00131.2018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Intracortical brain-computer interfaces (BCIs) can enable individuals to control effectors, such as a computer cursor, by directly decoding the user's movement intentions from action potentials and local field potentials (LFPs) recorded within the motor cortex. However, the accuracy and complexity of effector control achieved with such "biomimetic" BCIs will depend on the degree to which the intended movements used to elicit control modulate the neural activity. In particular, channels that do not record distinguishable action potentials and only record LFP modulations may be of limited use for BCI control. In contrast, a biofeedback approach may surpass these limitations by letting the participants generate new control signals and learn strategies that improve the volitional control of signals used for effector control. Here, we show that, by using a biofeedback paradigm, three individuals with tetraplegia achieved volitional control of gamma LFPs (40-400 Hz) recorded by a single microelectrode implanted in the precentral gyrus. Control was improved over a pair of consecutive sessions up to 3 days apart. In all but one session, the channel used to achieve control lacked distinguishable action potentials. Our results indicate that biofeedback LFP-based BCIs may potentially contribute to the neural modulation necessary to obtain reliable and useful control of effectors. NEW & NOTEWORTHY Our study demonstrates that people with tetraplegia can volitionally control individual high-gamma local-field potential (LFP) channels recorded from the motor cortex, and that this control can be improved using biofeedback. Motor cortical LFP signals are thought to be both informative and stable intracortical signals and, thus, of importance for future brain-computer interfaces.
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Affiliation(s)
- Tomislav Milekovic
- Department of Neuroscience, Brown University , Providence, Rhode Island.,Carney Institute for Brain Science, Brown University , Providence, Rhode Island.,Department of Fundamental Neuroscience, Faculty of Medicine, University of Geneva , Geneva , Switzerland
| | - Daniel Bacher
- Carney Institute for Brain Science, Brown University , Providence, Rhode Island.,School of Engineering, Brown University , Providence, Rhode Island
| | - Anish A Sarma
- Carney Institute for Brain Science, Brown University , Providence, Rhode Island.,School of Engineering, Brown University , Providence, Rhode Island.,Center for Neurorestoration and Neurotechnology, Rehabilitation Research & Development Service, Department of Veterans Affairs , Providence, Rhode Island
| | - John D Simeral
- Carney Institute for Brain Science, Brown University , Providence, Rhode Island.,School of Engineering, Brown University , Providence, Rhode Island.,Center for Neurorestoration and Neurotechnology, Rehabilitation Research & Development Service, Department of Veterans Affairs , Providence, Rhode Island
| | - Jad Saab
- Carney Institute for Brain Science, Brown University , Providence, Rhode Island.,School of Engineering, Brown University , Providence, Rhode Island
| | - Chethan Pandarinath
- Department of Neurosurgery, Stanford University , Stanford, California.,Department of Electrical Engineering, Stanford University , Stanford, California.,Stanford Neurosciences Institute, Stanford University , Stanford, California
| | - Blaise Yvert
- Department of Neuroscience, Brown University , Providence, Rhode Island.,Carney Institute for Brain Science, Brown University , Providence, Rhode Island.,Inserm, University of Grenoble, Clinatec-Lab U1205, Grenoble , France
| | - Brittany L Sorice
- Department of Neurology, Massachusetts General Hospital , Boston, Massachusetts
| | - Christine Blabe
- Department of Neurosurgery, Stanford University , Stanford, California
| | - Erin M Oakley
- Department of Neurology, Massachusetts General Hospital , Boston, Massachusetts
| | - Kathryn R Tringale
- Department of Neurology, Massachusetts General Hospital , Boston, Massachusetts
| | - Emad Eskandar
- Department of Neurosurgery, Massachusetts General Hospital , Boston, Massachusetts.,Harvard Medical School , Boston, Massachusetts
| | - Sydney S Cash
- Department of Neurology, Massachusetts General Hospital , Boston, Massachusetts.,Harvard Medical School , Boston, Massachusetts
| | - Krishna V Shenoy
- Department of Electrical Engineering, Stanford University , Stanford, California.,Stanford Neurosciences Institute, Stanford University , Stanford, California.,Neurosciences Program, Stanford University , Stanford, California.,Department of Neurobiology, Stanford University , Stanford, California.,Department of Bioengineering, Stanford University , Stanford, California
| | - Jaimie M Henderson
- Department of Neurosurgery, Stanford University , Stanford, California.,Stanford Neurosciences Institute, Stanford University , Stanford, California.,Department of Neurology and Neurological Sciences, Stanford University , Stanford, California
| | - Leigh R Hochberg
- Carney Institute for Brain Science, Brown University , Providence, Rhode Island.,School of Engineering, Brown University , Providence, Rhode Island.,Center for Neurorestoration and Neurotechnology, Rehabilitation Research & Development Service, Department of Veterans Affairs , Providence, Rhode Island.,Department of Neurology, Massachusetts General Hospital , Boston, Massachusetts.,Harvard Medical School , Boston, Massachusetts
| | - John P Donoghue
- Department of Neuroscience, Brown University , Providence, Rhode Island.,Carney Institute for Brain Science, Brown University , Providence, Rhode Island.,Center for Neurorestoration and Neurotechnology, Rehabilitation Research & Development Service, Department of Veterans Affairs , Providence, Rhode Island
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16
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Progress in the Field of Micro-Electrocorticography. MICROMACHINES 2019; 10:mi10010062. [PMID: 30658503 PMCID: PMC6356841 DOI: 10.3390/mi10010062] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 01/10/2019] [Accepted: 01/15/2019] [Indexed: 12/30/2022]
Abstract
Since the 1940s electrocorticography (ECoG) devices and, more recently, in the last decade, micro-electrocorticography (µECoG) cortical electrode arrays were used for a wide set of experimental and clinical applications, such as epilepsy localization and brain⁻computer interface (BCI) technologies. Miniaturized implantable µECoG devices have the advantage of providing greater-density neural signal acquisition and stimulation capabilities in a minimally invasive fashion. An increased spatial resolution of the µECoG array will be useful for greater specificity diagnosis and treatment of neuronal diseases and the advancement of basic neuroscience and BCI research. In this review, recent achievements of ECoG and µECoG are discussed. The electrode configurations and varying material choices used to design µECoG arrays are discussed, including advantages and disadvantages of µECoG technology compared to electroencephalography (EEG), ECoG, and intracortical electrode arrays. Electrode materials that are the primary focus include platinum, iridium oxide, poly(3,4-ethylenedioxythiophene) (PEDOT), indium tin oxide (ITO), and graphene. We discuss the biological immune response to µECoG devices compared to other electrode array types, the role of µECoG in clinical pathology, and brain⁻computer interface technology. The information presented in this review will be helpful to understand the current status, organize available knowledge, and guide future clinical and research applications of µECoG technologies.
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17
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Abstract
Hydrogels have emerged as a promising bioelectronic interfacing material. This review discusses the fundamentals and recent advances in hydrogel bioelectronics.
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Affiliation(s)
- Hyunwoo Yuk
- Department of Mechanical Engineering
- Massachusetts Institute of Technology
- Cambridge
- USA
| | - Baoyang Lu
- Department of Mechanical Engineering
- Massachusetts Institute of Technology
- Cambridge
- USA
- School of Pharmacy
| | - Xuanhe Zhao
- Department of Mechanical Engineering
- Massachusetts Institute of Technology
- Cambridge
- USA
- Department of Civil and Environmental Engineering
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18
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Goding J, Vallejo-Giraldo C, Syed O, Green R. Considerations for hydrogel applications to neural bioelectronics. J Mater Chem B 2019; 7:1625-1636. [DOI: 10.1039/c8tb02763c] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Hydrogels have garnered interest as materials in bioelectronics due to the capacity to tailor their properties. Appropriate selection and design of hydrogel systems for this application requires an understanding of the physical, chemical and biological properties as well as their structure–property relationships.
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Affiliation(s)
- Josef Goding
- Department of Bioengineering
- Imperial College London
- London SW72AS
- UK
| | | | - Omaer Syed
- Department of Bioengineering
- Imperial College London
- London SW72AS
- UK
| | - Rylie Green
- Department of Bioengineering
- Imperial College London
- London SW72AS
- UK
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19
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Advances in Penetrating Multichannel Microelectrodes Based on the Utah Array Platform. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1101:1-40. [PMID: 31729670 DOI: 10.1007/978-981-13-2050-7_1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The Utah electrode array (UEA) and its many derivatives have become a gold standard for high-channel count bi-directional neural interfaces, in particular in human subject applications. The chapter provides a brief overview of leading electrode concepts and the context in which the UEA has to be understood. It goes on to discuss the key advances and developments of the UEA platform in the past 15 years, as well as novel wireless and system integration technologies that will merge into future generations of fully integrated devices. Aspects covered include novel device architectures that allow scaling of channel count and density of electrode contacts, material improvements to substrate, electrode contacts, and encapsulation. Further subjects are adaptations of the UEA platform to support IR and optogenetic simulation as well as an improved understanding of failure modes and methods to test and accelerate degradation in vitro such as to better predict device failure and lifetime in vivo.
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20
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Stiller AM, Usoro J, Frewin CL, Danda VR, Ecker M, Joshi-Imre A, Musselman KC, Voit W, Modi R, Pancrazio JJ, Black BJ. Chronic Intracortical Recording and Electrochemical Stability of Thiol-ene/Acrylate Shape Memory Polymer Electrode Arrays. MICROMACHINES 2018; 9:E500. [PMID: 30424433 PMCID: PMC6215160 DOI: 10.3390/mi9100500] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2018] [Revised: 09/24/2018] [Accepted: 09/27/2018] [Indexed: 11/20/2022]
Abstract
Current intracortical probe technology is limited in clinical implementation due to the short functional lifetime of implanted devices. Devices often fail several months to years post-implantation, likely due to the chronic immune response characterized by glial scarring and neuronal dieback. It has been demonstrated that this neuroinflammatory response is influenced by the mechanical mismatch between stiff devices and the soft brain tissue, spurring interest in the use of softer polymer materials for probe encapsulation. Here, we demonstrate stable recordings and electrochemical properties obtained from fully encapsulated shape memory polymer (SMP) intracortical electrodes implanted in the rat motor cortex for 13 weeks. SMPs are a class of material that exhibit modulus changes when exposed to specific conditions. The formulation used in these devices softens by an order of magnitude after implantation compared to its dry, room-temperature modulus of ~2 GPa.
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Affiliation(s)
- Allison M Stiller
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX 75080, USA.
| | - Joshua Usoro
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX 75080, USA.
| | - Christopher L Frewin
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX 75080, USA.
| | - Vindhya R Danda
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX 75080, USA.
- Qualia, Inc., Dallas, TX 75252, USA.
| | - Melanie Ecker
- Department of Materials Science and Engineering, The University of Texas at Dallas, Richardson, TX 75080, USA.
| | - Alexandra Joshi-Imre
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX 75080, USA.
| | - Kate C Musselman
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX 75080, USA.
| | - Walter Voit
- Qualia, Inc., Dallas, TX 75252, USA.
- Department of Materials Science and Engineering, The University of Texas at Dallas, Richardson, TX 75080, USA.
| | | | - Joseph J Pancrazio
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX 75080, USA.
| | - Bryan J Black
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX 75080, USA.
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21
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Shepherd RK, Villalobos J, Burns O, Nayagam DAX. The development of neural stimulators: a review of preclinical safety and efficacy studies. J Neural Eng 2018; 15:041004. [PMID: 29756600 PMCID: PMC6049833 DOI: 10.1088/1741-2552/aac43c] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Given the rapid expansion of the field of neural stimulation and the rigorous regulatory approval requirements required before these devices can be applied clinically, it is important that there is clarity around conducting preclinical safety and efficacy studies required for the development of this technology. APPROACH The present review examines basic design principles associated with the development of a safe neural stimulator and describes the suite of preclinical safety studies that need to be considered when taking a device to clinical trial. MAIN RESULTS Neural stimulators are active implantable devices that provide therapeutic intervention, sensory feedback or improved motor control via electrical stimulation of neural or neuro-muscular tissue in response to trauma or disease. Because of their complexity, regulatory bodies classify these devices in the highest risk category (Class III), and they are therefore required to go through a rigorous regulatory approval process before progressing to market. The successful development of these devices is achieved through close collaboration across disciplines including engineers, scientists and a surgical/clinical team, and the adherence to clear design principles. Preclinical studies form one of several key components in the development pathway from concept to product release of neural stimulators. Importantly, these studies provide iterative feedback in order to optimise the final design of the device. Key components of any preclinical evaluation include: in vitro studies that are focussed on device reliability and include accelerated testing under highly controlled environments; in vivo studies using animal models of the disease or injury in order to assess efficacy and, given an appropriate animal model, the safety of the technology under both passive and electrically active conditions; and human cadaver and ex vivo studies designed to ensure the device's form factor conforms to human anatomy, to optimise the surgical approach and to develop any specialist surgical tooling required. SIGNIFICANCE The pipeline from concept to commercialisation of these devices is long and expensive; careful attention to both device design and its preclinical evaluation will have significant impact on the duration and cost associated with taking a device through to commercialisation. Carefully controlled in vitro and in vivo studies together with ex vivo and human cadaver trials are key components of a thorough preclinical evaluation of any new neural stimulator.
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Affiliation(s)
- Robert K Shepherd
- Bionics Institute, East Melbourne, Australia. Medical Bionics Department, University of Melbourne, Melbourne, Australia
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22
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Szostak KM, Grand L, Constandinou TG. Neural Interfaces for Intracortical Recording: Requirements, Fabrication Methods, and Characteristics. Front Neurosci 2017; 11:665. [PMID: 29270103 PMCID: PMC5725438 DOI: 10.3389/fnins.2017.00665] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 11/15/2017] [Indexed: 01/30/2023] Open
Abstract
Implantable neural interfaces for central nervous system research have been designed with wire, polymer, or micromachining technologies over the past 70 years. Research on biocompatible materials, ideal probe shapes, and insertion methods has resulted in building more and more capable neural interfaces. Although the trend is promising, the long-term reliability of such devices has not yet met the required criteria for chronic human application. The performance of neural interfaces in chronic settings often degrades due to foreign body response to the implant that is initiated by the surgical procedure, and related to the probe structure, and material properties used in fabricating the neural interface. In this review, we identify the key requirements for neural interfaces for intracortical recording, describe the three different types of probes-microwire, micromachined, and polymer-based probes; their materials, fabrication methods, and discuss their characteristics and related challenges.
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Affiliation(s)
- Katarzyna M. Szostak
- Next Generation Neural Interfaces Lab, Department of Electrical and Electronic Engineering, Centre for Bio-Inspired Technology, Imperial College London, London, United Kingdom
| | - Laszlo Grand
- Next Generation Neural Interfaces Lab, Department of Electrical and Electronic Engineering, Centre for Bio-Inspired Technology, Imperial College London, London, United Kingdom
- Department of Neurology and Neurosurgery, Johns Hopkins University, Baltimore, MD, United States
| | - Timothy G. Constandinou
- Next Generation Neural Interfaces Lab, Department of Electrical and Electronic Engineering, Centre for Bio-Inspired Technology, Imperial College London, London, United Kingdom
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23
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Tuft BW, Xu L, Leigh B, Lee D, Guymon CA, Hansen MR. Photopolymerized micropatterns with high feature frequencies overcome chemorepulsive borders to direct neurite growth. J Tissue Eng Regen Med 2017; 12:e1392-e1403. [PMID: 28753740 DOI: 10.1002/term.2527] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 07/03/2017] [Accepted: 07/24/2017] [Indexed: 01/04/2023]
Abstract
Developing and regenerating neurites respond to a variety of biophysical and biochemical cues in their micro-environment to reach target cells and establish appropriate synapses. Defining the hierarchal relationship of both types of cues to direct neurite growth carries broad significance for neural development, regeneration, and, in particular, engineering of neural prostheses that improve tissue integration with native neural networks. In this work, chemorepulsive biochemical borders are established on substrates with a range of surface microfeatures to determine the potential of physical cues to overcome conflicting biochemical cues. Physical micropatterns are fabricated using photomasking techniques to spatially control photoinitiation events of the polymerization. Temporal control of the reaction allows for generation of microfeatures with the same amplitude across a range of feature frequencies or periodicities. The micropatterned substrates are then modified with repulsive chemical borders between laminin and either EphA4-Fc or tenascin C that compete with the surface microfeatures to direct neurite growth. Behaviour of neurites from spiral ganglion and trigeminal neurons is characterized at biochemical borders as cross, turn, stop, or repel events. Both the chemical borders and physical patterns significantly influence neurite pathfinding. On unpatterned surfaces, most neurites that originate on laminin are deterred by the border with tenascin C or EphA4-Fc. Importantly, substrates with frequent micropattern features overcome the influence of the chemorepulsive border to dominate neurite trajectory. Designing prosthesis interfaces with appropriate surface features may allow for spatially organized neurite outgrowth in vivo even in the presence of conflicting biochemical cues in native target tissues.
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Affiliation(s)
- Bradley W Tuft
- Department of Chemical and Biochemical Engineering, University of Iowa, Iowa City, IA, USA
| | - Linjing Xu
- Department of Otolaryngology - Head and Neck Surgery, University of Iowa, Iowa City, IA, USA
| | - Braden Leigh
- Department of Chemical and Biochemical Engineering, University of Iowa, Iowa City, IA, USA
| | - Daniel Lee
- Department of Otolaryngology - Head and Neck Surgery, University of Iowa, Iowa City, IA, USA
| | - C Allan Guymon
- Department of Chemical and Biochemical Engineering, University of Iowa, Iowa City, IA, USA
| | - Marlan R Hansen
- Department of Otolaryngology - Head and Neck Surgery, University of Iowa, Iowa City, IA, USA.,Department of Neurosurgery, University of Iowa, Iowa City, IA, USA
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24
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Mols K, Musa S, Nuttin B, Lagae L, Bonin V. In vivo characterization of the electrophysiological and astrocytic responses to a silicon neuroprobe implanted in the mouse neocortex. Sci Rep 2017; 7:15642. [PMID: 29142267 PMCID: PMC5688150 DOI: 10.1038/s41598-017-15121-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 10/23/2017] [Indexed: 12/04/2022] Open
Abstract
Silicon neuroprobes hold great potential for studies of large-scale neural activity and brain computer interfaces, but data on brain response in chronic implants is limited. Here we explored with in vivo cellular imaging the response to multisite silicon probes for neural recordings. We tested a chronic implant for mice consisting of a CMOS-compatible silicon probe rigidly implanted in the cortex under a cranial imaging window. Multiunit recordings of cortical neurons with the implant showed no degradation of electrophysiological signals weeks after implantation (mean spike and noise amplitudes of 186 ± 42 µVpp and 16 ± 3.2 µVrms, respectively, n = 5 mice). Two-photon imaging through the cranial window allowed longitudinal monitoring of fluorescently-labeled astrocytes from the second week post implantation for 8 weeks (n = 3 mice). The imaging showed a local increase in astrocyte-related fluorescence that remained stable from the second to the tenth week post implantation. These results demonstrate that, in a standard electrophysiology protocol in mice, rigidly implanted silicon probes can provide good short to medium term chronic recording performance with a limited astrocyte inflammatory response. The precise factors influencing the response to silicon probe implants remain to be elucidated.
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Affiliation(s)
- Katrien Mols
- Neuro-Electronics Research Flanders, Kapeldreef 75, 3001, Leuven, Belgium.,imec, Department of Life Science Technologies, Kapeldreef 75, 3001, Leuven, Belgium.,KU Leuven, Department of Neurosciences, 3000, Leuven, Belgium
| | - Silke Musa
- imec, Department of Life Science Technologies, Kapeldreef 75, 3001, Leuven, Belgium
| | - Bart Nuttin
- KU Leuven, Department of Neurosciences, 3000, Leuven, Belgium
| | - Liesbet Lagae
- imec, Department of Life Science Technologies, Kapeldreef 75, 3001, Leuven, Belgium.,KU Leuven, Department of Physics and Astronomy, 3001, Leuven, Belgium
| | - Vincent Bonin
- Neuro-Electronics Research Flanders, Kapeldreef 75, 3001, Leuven, Belgium. .,Vlaams Instituut voor Biotechnologie (VIB), 3001, Leuven, Belgium. .,KU Leuven, Department of Biology, 3000, Leuven, Belgium.
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25
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Leigh BL, Truong K, Bartholomew R, Ramirez M, Hansen MR, Allan Guymon C. Tuning Surface and Topographical Features to Investigate Competitive Guidance of Spiral Ganglion Neurons. ACS APPLIED MATERIALS & INTERFACES 2017; 9:31488-31496. [PMID: 28841276 PMCID: PMC6341486 DOI: 10.1021/acsami.7b09258] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Cochlear Implants (CIs) suffer from limited tonal resolution due, in large part, to spatial separation between stimulating electrode arrays and primary neural receptors. In this work, a combination of physical and chemical micropatterns, formed on acrylate polymers, are used to direct the growth of primary spiral ganglion neurons (SGNs), the inner ear neurons. Utilizing the inherent temporal and spatial control of photopolymerization, physical microgrooves are fabricated using a photomask in a single step process. Biochemical patterns are generated by adsorbing laminin, a cell adhesion protein, to acrylate polymer surfaces followed by irradiation through a photomask with UV light to deactivate protein in exposed areas and generate parallel biochemical patterns. Laminin deactivation was shown increase as a function of UV light exposure while remaining adsorbed to the polymer surface. SGN neurites show alignment to both biochemical and physical patterns when evaluated individually. Competing biochemical and physical patterns were also examined. The relative guiding strength of physical cues was varied by independently changing both the amplitude and the band spacing of the microgrooves, with higher amplitudes and shorter band spacing providing cues that more effective guide neurite growth. SGN neurites aligned to laminin patterns with lower physical pattern amplitude and thus weaker physical cues. Alignment of SGNs shifted toward the physical pattern with higher amplitude and lower periodicity patterns which represent stronger cues. These results demonstrate the ability of photopolymerized microfeatures to modulate alignment of inner ear neurites even in the presence of conflicting physical and biochemical cues laying the groundwork for next generation cochlear implants and neural prosthetic devices.
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Affiliation(s)
- Braden L. Leigh
- Departments of Chemical and Biochemical Engineering, University of Iowa, Iowa City, IA 52242, USA
| | - Kristy Truong
- Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, USA
| | - Reid Bartholomew
- Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, USA
| | - Mark Ramirez
- Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, USA
| | - Marlan R. Hansen
- Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, USA
- Neurosurgery, University of Iowa, Iowa City, IA 52242, USA
| | - C. Allan Guymon
- Departments of Chemical and Biochemical Engineering, University of Iowa, Iowa City, IA 52242, USA
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Abstract
A major challenge in the growing field of bioelectronic medicine is the development of tissue interface technologies promoting device integration with biological tissues. Materials based on organic bioelectronics show great promise due to a unique combination of electronic and ionic conductivity properties. In this review, we outline exciting developments in the field of organic bioelectronics and demonstrate the medical importance of these active, electronically controllable materials. Importantly, organic bioelectronics offer a means to control cell-surface attachment as required for many device-tissue applications. Experiments have shown that cells readily attach and proliferate on reduced but not oxidized organic bioelectronic materials. In another application, the active properties of organic bioelectronics were used to develop electronically triggered systems for drug release. After incorporating drugs by advanced loading strategies, small compound drugs were released upon electrochemical trigger, independent of charge. Another type of delivery device was used to achieve well-controlled, spatiotemporal delivery of cationic drugs. Via electrophoretic transport within a polymer, cations were delivered with single-cell precision. Finally, organic bioelectronic materials are commonly used as electrode coatings improving the electrical properties of recording and stimulation electrodes. Because such coatings drastically reduce the electrode impedance, smaller electrodes with improved signal-to-noise ratio can be fabricated. Thus, rapid technological advancement combined with the creation of tiny electronic devices reacting to changes in the tissue environment helps to promote the transition from standard pharmaceutical therapy to treatment based on 'electroceuticals'. Moreover, the widening repertoire of organic bioelectronics will expand the options for true biological interfaces, providing the basis for personalized bioelectronic medicine.
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Affiliation(s)
- S Löffler
- Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - K Melican
- Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - K P R Nilsson
- Division of Chemistry, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden
| | - A Richter-Dahlfors
- Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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Du ZJ, Kolarcik CL, Kozai TDY, Luebben SD, Sapp SA, Zheng XS, Nabity JA, Cui XT. Ultrasoft microwire neural electrodes improve chronic tissue integration. Acta Biomater 2017; 53:46-58. [PMID: 28185910 DOI: 10.1016/j.actbio.2017.02.010] [Citation(s) in RCA: 109] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Revised: 02/02/2017] [Accepted: 02/05/2017] [Indexed: 12/11/2022]
Abstract
Chronically implanted neural multi-electrode arrays (MEA) are an essential technology for recording electrical signals from neurons and/or modulating neural activity through stimulation. However, current MEAs, regardless of the type, elicit an inflammatory response that ultimately leads to device failure. Traditionally, rigid materials like tungsten and silicon have been employed to interface with the relatively soft neural tissue. The large stiffness mismatch is thought to exacerbate the inflammatory response. In order to minimize the disparity between the device and the brain, we fabricated novel ultrasoft electrodes consisting of elastomers and conducting polymers with mechanical properties much more similar to those of brain tissue than previous neural implants. In this study, these ultrasoft microelectrodes were inserted and released using a stainless steel shuttle with polyethyleneglycol (PEG) glue. The implanted microwires showed functionality in acute neural stimulation. When implanted for 1 or 8weeks, the novel soft implants demonstrated significantly reduced inflammatory tissue response at week 8 compared to tungsten wires of similar dimension and surface chemistry. Furthermore, a higher degree of cell body distortion was found next to the tungsten implants compared to the polymer implants. Our results support the use of these novel ultrasoft electrodes for long term neural implants. STATEMENT OF SIGNIFICANCE One critical challenge to the translation of neural recording/stimulation electrode technology to clinically viable devices for brain computer interface (BCI) or deep brain stimulation (DBS) applications is the chronic degradation of device performance due to the inflammatory tissue reaction. While many hypothesize that soft and flexible devices elicit reduced inflammatory tissue responses, there has yet to be a rigorous comparison between soft and stiff implants. We have developed an ultra-soft microelectrode with Young's modulus lower than 1MPa, closely mimicking the brain tissue modulus. Here, we present a rigorous histological comparison of this novel ultrasoft electrode and conventional stiff electrode with the same size, shape and surface chemistry, implanted in rat brains for 1-week and 8-weeks. Significant improvement was observed for ultrasoft electrodes, including inflammatory tissue reaction, electrode-tissue integration as well as mechanical disturbance to nearby neurons. A full spectrum of new techniques were developed in this study, from insertion shuttle to in situ sectioning of the microelectrode to automated cell shape analysis, all of which should contribute new methods to the field. Finally, we showed the electrical functionality of the ultrasoft electrode, demonstrating the potential of flexible neural implant devices for future research and clinical use.
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Affiliation(s)
- Zhanhong Jeff Du
- Department of Bioengineering, University of Pittsburgh, PA, USA; Center for the Neural Basis of Cognition, University of Pittsburgh, PA, USA; McGowan Institute for Regenerative Medicine, University of Pittsburgh, PA, USA; Shenzhen Key Lab of Neuropsychiatric Modulation, CAS Center for Excellence in Brain Science, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Christi L Kolarcik
- Department of Bioengineering, University of Pittsburgh, PA, USA; Center for the Neural Basis of Cognition, University of Pittsburgh, PA, USA; McGowan Institute for Regenerative Medicine, University of Pittsburgh, PA, USA; Systems Neuroscience Institute, University of Pittsburgh, PA, USA
| | - Takashi D Y Kozai
- Department of Bioengineering, University of Pittsburgh, PA, USA; Center for the Neural Basis of Cognition, University of Pittsburgh, PA, USA; McGowan Institute for Regenerative Medicine, University of Pittsburgh, PA, USA; NeuroTech Center of Brain Institute, University of Pittsburgh, PA, USA
| | | | | | - Xin Sally Zheng
- Department of Bioengineering, University of Pittsburgh, PA, USA
| | - James A Nabity
- Department of Aerospace Engineering Sciences, University of Colorado, Boulder, CO,USA
| | - X Tracy Cui
- Department of Bioengineering, University of Pittsburgh, PA, USA; Center for the Neural Basis of Cognition, University of Pittsburgh, PA, USA; McGowan Institute for Regenerative Medicine, University of Pittsburgh, PA, USA.
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Seyock S, Maybeck V, Offenhäusser A. How to image cell adhesion on soft polymers? Micron 2016; 92:39-42. [PMID: 27866099 DOI: 10.1016/j.micron.2016.11.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 11/07/2016] [Accepted: 11/07/2016] [Indexed: 11/25/2022]
Abstract
Here, we present a method to investigate cell adhesion on soft, non-conducting polymers that are implant candidate materials. Neuronal cells were grown on two elastomers (polydimethylsiloxane (PDMS) and Ecoflex®) and prepared for electron microscopy. The samples were treated with osmium tetroxide (OsO4) and uranylacetate (UrAc). Best results can be achieved when the polymers were coated with a thin iridium layer before the cell culture. This was done to emphasize the usage of soft polymers as supports for implant electrodes. A good contrast and the adhesion of the cells on soft polymers could be visualized.
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Affiliation(s)
- Silke Seyock
- Institute of Complex Systems (ICS-8/PGI-8), Forschungszentrum Jülich, 52428 Jülich, Germany
| | - Vanessa Maybeck
- Institute of Complex Systems (ICS-8/PGI-8), Forschungszentrum Jülich, 52428 Jülich, Germany
| | - Andreas Offenhäusser
- Institute of Complex Systems (ICS-8/PGI-8), Forschungszentrum Jülich, 52428 Jülich, Germany.
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Torregrosa T, Koppes RA. Bioelectric Medicine and Devices for the Treatment of Spinal Cord Injury. Cells Tissues Organs 2016; 202:6-22. [PMID: 27701161 DOI: 10.1159/000446698] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/09/2016] [Indexed: 11/19/2022] Open
Abstract
Recovery of motor control is paramount for patients living with paralysis following spinal cord injury (SCI). While a cure or regenerative intervention remains on the horizon for the treatment of SCI, a number of neuroprosthetic devices have been employed to treat and mitigate the symptoms of paralysis associated with injuries to the spinal column and associated comorbidities. The recent success of epidural stimulation to restore voluntary motor function in the lower limbs of a small cohort of patients has breathed new life into the promise of electric-based medicine. Recently, a number of new organic and inorganic electronic devices have been developed for brain-computer interfaces to bypass the injury, for neurorehabilitation, bladder and bowel control, and the restoration of motor or sensory control. Herein, we discuss the recent advances in neuroprosthetic devices for treating SCI and highlight future design needs for closed-loop device systems.
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Etemadi L, Mohammed M, Thorbergsson PT, Ekstrand J, Friberg A, Granmo M, Pettersson LME, Schouenborg J. Embedded Ultrathin Cluster Electrodes for Long-Term Recordings in Deep Brain Centers. PLoS One 2016; 11:e0155109. [PMID: 27159159 PMCID: PMC4861347 DOI: 10.1371/journal.pone.0155109] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 04/25/2016] [Indexed: 01/03/2023] Open
Abstract
Neural interfaces which allow long-term recordings in deep brain structures in awake freely moving animals have the potential of becoming highly valuable tools in neuroscience. However, the recording quality usually deteriorates over time, probably at least partly due to tissue reactions caused by injuries during implantation, and subsequently micro-forces due to a lack of mechanical compliance between the tissue and neural interface. To address this challenge, we developed a gelatin embedded neural interface comprising highly flexible electrodes and evaluated its long term recording properties. Bundles of ultrathin parylene C coated platinum electrodes (N = 29) were embedded in a hard gelatin based matrix shaped like a needle, and coated with Kollicoat™ to retard dissolution of gelatin during the implantation. The implantation parameters were established in an in vitro model of the brain (0.5% agarose). Following a craniotomy in the anesthetized rat, the gelatin embedded electrodes were stereotactically inserted to a pre-target position, and after gelatin dissolution the electrodes were further advanced and spread out in the area of the subthalamic nucleus (STN). The performance of the implanted electrodes was evaluated under anesthesia, during 8 weeks. Apart from an increase in the median-noise level during the first 4 weeks, the electrode impedance and signal-to-noise ratio of single-units remained stable throughout the experiment. Histological postmortem analysis confirmed implantation in the area of STN in most animals. In conclusion, by combining novel biocompatible implantation techniques and ultra-flexible electrodes, long-term neuronal recordings from deep brain structures with no significant deterioration of electrode function were achieved.
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Affiliation(s)
- Leila Etemadi
- Neuronano Research Center, Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Mohsin Mohammed
- Neuronano Research Center, Department of Experimental Medical Science, Lund University, Lund, Sweden
- * E-mail: (MM); (JS); (LP)
| | - Palmi Thor Thorbergsson
- Neuronano Research Center, Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Joakim Ekstrand
- Neuronano Research Center, Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Annika Friberg
- Neuronano Research Center, Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Marcus Granmo
- Neuronano Research Center, Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Lina M. E. Pettersson
- Neuronano Research Center, Department of Experimental Medical Science, Lund University, Lund, Sweden
- * E-mail: (MM); (JS); (LP)
| | - Jens Schouenborg
- Neuronano Research Center, Department of Experimental Medical Science, Lund University, Lund, Sweden
- * E-mail: (MM); (JS); (LP)
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31
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Prodanov D, Delbeke J. Mechanical and Biological Interactions of Implants with the Brain and Their Impact on Implant Design. Front Neurosci 2016; 10:11. [PMID: 26903786 PMCID: PMC4746296 DOI: 10.3389/fnins.2016.00011] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Accepted: 01/11/2016] [Indexed: 11/26/2022] Open
Abstract
Neural prostheses have already a long history and yet the cochlear implant remains the only success story about a longterm sensory function restoration. On the other hand, neural implants for deep brain stimulation are gaining acceptance for variety of disorders including Parkinsons disease and obsessive-compulsive disorder. It is anticipated that the progress in the field has been hampered by a combination of technological and biological factors, such as the limited understanding of the longterm behavior of implants, unreliability of devices, biocompatibility of the implants among others. While the field's understanding of the cell biology of interactions at the biotic-abiotic interface has improved, relatively little attention has been paid on the mechanical factors (stress, strain), and hence on the geometry that can modulate it. This focused review summarizes the recent progress in the understanding of the mechanisms of mechanical interaction between the implants and the brain. The review gives an overview of the factors by which the implants interact acutely and chronically with the tissue: blood-brain barrier (BBB) breach, vascular damage, micromotions, diffusion etc. We propose some design constraints to be considered in future studies. Aspects of the chronic cell-implant interaction will be discussed in view of the chronic local inflammation and the ways of modulating it.
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Affiliation(s)
- Dimiter Prodanov
- Department of Environment, Health and Safety, ImecLeuven, Belgium
- Neuroscience Research FlandersLeuven, Belgium
| | - Jean Delbeke
- LCEN3, Department of Neurology, Institute of Neuroscience, Ghent UniversityGhent, Belgium
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Angelov SD, Koenen S, Jakobi J, Heissler HE, Alam M, Schwabe K, Barcikowski S, Krauss JK. Electrophoretic deposition of ligand-free platinum nanoparticles on neural electrodes affects their impedance in vitro and in vivo with no negative effect on reactive gliosis. J Nanobiotechnology 2016; 14:3. [PMID: 26753543 PMCID: PMC4710003 DOI: 10.1186/s12951-015-0154-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2015] [Accepted: 12/22/2015] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Electrodes for neural stimulation and recording are used for the treatment of neurological disorders. Their features critically depend on impedance and interaction with brain tissue. The effect of surface modification on electrode impedance was examined in vitro and in vivo after intracranial implantation in rats. Electrodes coated by electrophoretic deposition with platinum nanoparticles (NP; <10 and 50 nm) as well as uncoated references were implanted into the rat's subthalamic nucleus. After postoperative recovery, rats were electrostimulated for 3 weeks. Impedance was measured before implantation, after recovery and then weekly during stimulation. Finally, local field potential was recorded and tissue-to-implant reaction was immunohistochemically studied. RESULTS Coating with NP significantly increased electrode's impedance in vitro. Postoperatively, the impedance of all electrodes was temporarily further increased. This effect was lowest for the electrodes coated with particles <10 nm, which also showed the most stable impedance dynamics during stimulation for 3 weeks and the lowest total power of local field potential during neuronal activity recording. Histological analysis revealed that NP-coating did not affect glial reactions or neural cell-count. CONCLUSIONS Coating with NP <10 nm may improve electrode's impedance stability without affecting biocompatibility. Increased impedance after NP-coating may improve neural recording due to better signal-to-noise ratio.
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Affiliation(s)
- Svilen D Angelov
- Department of Neurosurgery, Hannover Medical School, Medical University Hannover, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.
| | - Sven Koenen
- Technical Chemistry I and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitätsstrasse 7, 45141, Essen, Germany.
| | - Jurij Jakobi
- Technical Chemistry I and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitätsstrasse 7, 45141, Essen, Germany.
| | - Hans E Heissler
- Department of Neurosurgery, Hannover Medical School, Medical University Hannover, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.
| | - Mesbah Alam
- Department of Neurosurgery, Hannover Medical School, Medical University Hannover, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.
| | - Kerstin Schwabe
- Department of Neurosurgery, Hannover Medical School, Medical University Hannover, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.
| | - Stephan Barcikowski
- Technical Chemistry I and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitätsstrasse 7, 45141, Essen, Germany.
| | - Joachim K Krauss
- Department of Neurosurgery, Hannover Medical School, Medical University Hannover, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.
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Agorelius J, Tsanakalis F, Friberg A, Thorbergsson PT, Pettersson LME, Schouenborg J. An array of highly flexible electrodes with a tailored configuration locked by gelatin during implantation-initial evaluation in cortex cerebri of awake rats. Front Neurosci 2015; 9:331. [PMID: 26441505 PMCID: PMC4585103 DOI: 10.3389/fnins.2015.00331] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 09/04/2015] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND A major challenge in the field of neural interfaces is to overcome the problem of poor stability of neuronal recordings, which impedes long-term studies of individual neurons in the brain. Conceivably, unstable recordings reflect relative movements between electrode and tissue. To address this challenge, we have developed a new ultra-flexible electrode array and evaluated its performance in awake non-restrained animals. METHODS An array of eight separated gold leads (4 × 10 μm), individually flexible in 3D, were cut from a gold sheet using laser milling and insulated with Parylene C. To provide structural support during implantation into rat cortex, the electrode array was embedded in a hard gelatin based material, which dissolves after implantation. Recordings were made during 3 weeks. At termination, the animals were perfused with fixative and frozen to prevent dislocation of the implanted electrodes. A thick slice of brain tissue, with the electrode array still in situ, was made transparent using methyl salicylate to evaluate the conformation of the implanted electrode array. RESULTS Median noise levels and signal/noise remained relatively stable during the 3 week observation period; 4.3-5.9 μV and 2.8-4.2, respectively. The spike amplitudes were often quite stable within recording sessions and for 15% of recordings where single-units were identified, the highest-SNR unit had an amplitude higher than 150 μV. In addition, high correlations (>0.96) between unit waveforms recorded at different time points were obtained for 58% of the electrode sites. The structure of the electrode array was well preserved 3 weeks after implantation. CONCLUSIONS A new implantable multichannel neural interface, comprising electrodes individually flexible in 3D that retain its architecture and functionality after implantation has been developed. Since the new neural interface design is adaptable, it offers a versatile tool to explore the function of various brain structures.
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Affiliation(s)
- Johan Agorelius
- Department of Experimental Medical Science, Neuronano Research Centre, Lund UniversityLund, Sweden
- The Nanometer Structure Consortium, Lund UniversityLund, Sweden
| | - Fotios Tsanakalis
- Department of Experimental Medical Science, Neuronano Research Centre, Lund UniversityLund, Sweden
| | - Annika Friberg
- Department of Experimental Medical Science, Neuronano Research Centre, Lund UniversityLund, Sweden
| | - Palmi T. Thorbergsson
- Department of Experimental Medical Science, Neuronano Research Centre, Lund UniversityLund, Sweden
| | - Lina M. E. Pettersson
- Department of Experimental Medical Science, Neuronano Research Centre, Lund UniversityLund, Sweden
| | - Jens Schouenborg
- Department of Experimental Medical Science, Neuronano Research Centre, Lund UniversityLund, Sweden
- The Nanometer Structure Consortium, Lund UniversityLund, Sweden
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Kolarcik CL, Luebben SD, Sapp SA, Hanner J, Snyder N, Kozai TDY, Chang E, Nabity JA, Nabity ST, Lagenaur CF, Cui XT. Elastomeric and soft conducting microwires for implantable neural interfaces. SOFT MATTER 2015; 11:4847-61. [PMID: 25993261 PMCID: PMC4466039 DOI: 10.1039/c5sm00174a] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Current designs for microelectrodes used for interfacing with the nervous system elicit a characteristic inflammatory response that leads to scar tissue encapsulation, electrical insulation of the electrode from the tissue and ultimately failure. Traditionally, relatively stiff materials like tungsten and silicon are employed which have mechanical properties several orders of magnitude different from neural tissue. This mechanical mismatch is thought to be a major cause of chronic inflammation and degeneration around the device. In an effort to minimize the disparity between neural interface devices and the brain, novel soft electrodes consisting of elastomers and intrinsically conducting polymers were fabricated. The physical, mechanical and electrochemical properties of these materials were extensively characterized to identify the formulations with the optimal combination of parameters including Young's modulus, elongation at break, ultimate tensile strength, conductivity, impedance and surface charge injection. Our final electrode has a Young's modulus of 974 kPa which is five orders of magnitude lower than tungsten and significantly lower than other polymer-based neural electrode materials. In vitro cell culture experiments demonstrated the favorable interaction between these soft materials and neurons, astrocytes and microglia, with higher neuronal attachment and a two-fold reduction in inflammatory microglia attachment on soft devices compared to stiff controls. Surface immobilization of neuronal adhesion proteins on these microwires further improved the cellular response. Finally, in vivo electrophysiology demonstrated the functionality of the elastomeric electrodes in recording single unit activity in the rodent visual cortex. The results presented provide initial evidence in support of the use of soft materials in neural interface applications.
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Affiliation(s)
- Christi L Kolarcik
- Department of Bioengineering, University of Pittsburgh, 5057 Biomedical Science Tower 3, 3501 Fifth Avenue, Pittsburgh, PA, USA.
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Zehr EP. Future think: cautiously optimistic about brain augmentation using tissue engineering and machine interface. Front Syst Neurosci 2015; 9:72. [PMID: 26042003 PMCID: PMC4436819 DOI: 10.3389/fnsys.2015.00072] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 04/22/2015] [Indexed: 11/14/2022] Open
Affiliation(s)
- E Paul Zehr
- Rehabilitation Neuroscience Laboratory, University Victoria Victoria, BC, Canada ; Human Discovery Science, International Collaboration on Repair Discoveries Vancouver, BC, Canada ; Centre for Biomedical Research, University of Victoria Victoria, BC, Canada ; Division of Medical Sciences, University of Victoria BC, Canada ; School of Exercise Science, Physical, and Health Education, University of Victoria Victoria, BC, Canada ; Zanshin Consulting, Inc. Victoria, BC, Canada
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Ersen A, Elkabes S, Freedman DS, Sahin M. Chronic tissue response to untethered microelectrode implants in the rat brain and spinal cord. J Neural Eng 2015; 12:016019. [PMID: 25605679 DOI: 10.1088/1741-2560/12/1/016019] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
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.
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Affiliation(s)
- Ali Ersen
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, USA
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37
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Jorfi M, Skousen JL, Weder C, Capadona JR. Progress towards biocompatible intracortical microelectrodes for neural interfacing applications. J Neural Eng 2014; 12:011001. [PMID: 25460808 DOI: 10.1088/1741-2560/12/1/011001] [Citation(s) in RCA: 218] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
To ensure long-term consistent neural recordings, next-generation intracortical microelectrodes are being developed with an increased emphasis on reducing the neuro-inflammatory response. The increased emphasis stems from the improved understanding of the multifaceted role that inflammation may play in disrupting both biologic and abiologic components of the overall neural interface circuit. To combat neuro-inflammation and improve recording quality, the field is actively progressing from traditional inorganic materials towards approaches that either minimizes the microelectrode footprint or that incorporate compliant materials, bioactive molecules, conducting polymers or nanomaterials. However, the immune-privileged cortical tissue introduces an added complexity compared to other biomedical applications that remains to be fully understood. This review provides a comprehensive reflection on the current understanding of the key failure modes that may impact intracortical microelectrode performance. In addition, a detailed overview of the current status of various materials-based approaches that have gained interest for neural interfacing applications is presented, and key challenges that remain to be overcome are discussed. Finally, we present our vision on the future directions of materials-based treatments to improve intracortical microelectrodes for neural interfacing.
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Affiliation(s)
- Mehdi Jorfi
- Adolphe Merkle Institute, University of Fribourg, Rte de l'Ancienne Papeterie, CH-1723 Marly, Switzerland
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Hall TM, Nazarpour K, Jackson A. Real-time estimation and biofeedback of single-neuron firing rates using local field potentials. Nat Commun 2014; 5:5462. [PMID: 25394574 PMCID: PMC4243238 DOI: 10.1038/ncomms6462] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Accepted: 10/02/2014] [Indexed: 12/14/2022] Open
Abstract
The long-term stability and low-frequency composition of local field potentials (LFPs) offer important advantages for robust and efficient neuroprostheses. However, cortical LFPs recorded by multi-electrode arrays are often assumed to contain only redundant information arising from the activity of large neuronal populations. Here we show that multichannel LFPs in monkey motor cortex each contain a slightly different mixture of distinctive slow potentials that accompany neuronal firing. As a result, the firing rates of individual neurons can be estimated with surprising accuracy. We implemented this method in a real-time biofeedback brain–machine interface, and found that monkeys could learn to modulate the activity of arbitrary neurons using feedback derived solely from LFPs. These findings provide a principled method for monitoring individual neurons without long-term recording of action potentials. The use of local field potential (LFP) brain signals may allow development of more efficient and robust neural prosthetic devices. Here, Hall et al. develop a method for estimation and biofeedback control of single-neuron firing rates using signals extracted from multiple low-frequency LFPs.
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Affiliation(s)
- Thomas M Hall
- Institute of Neuroscience, Medical School, Newcastle University, Newcastle-upon-Tyne NE2 4HH, UK
| | - Kianoush Nazarpour
- 1] Institute of Neuroscience, Medical School, Newcastle University, Newcastle-upon-Tyne NE2 4HH, UK [2] School of Electrical and Electronic Engineering, Newcastle University, Newcastle-upon-Tyne NE1 7RU, UK
| | - Andrew Jackson
- Institute of Neuroscience, Medical School, Newcastle University, Newcastle-upon-Tyne NE2 4HH, UK
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Tuft BW, Zhang L, Xu L, Hangartner A, Leigh B, Hansen MR, Guymon CA. Material stiffness effects on neurite alignment to photopolymerized micropatterns. Biomacromolecules 2014; 15:3717-27. [PMID: 25211120 PMCID: PMC4195519 DOI: 10.1021/bm501019s] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The ability to direct neurite growth into a close proximity of stimulating elements of a neural prosthesis, such as a retinal or cochlear implant (CI), may enhance device performance and overcome current spatial signal resolution barriers. In this work, spiral ganglion neurons (SGNs), which are the target neurons to be stimulated by CIs, were cultured on photopolymerized micropatterns with varied matrix stiffnesses to determine the effect of rigidity on neurite alignment to physical cues. Micropatterns were generated on methacrylate thin film surfaces in a simple, rapid photopolymerization step by photomasking the prepolymer formulation with parallel line-space gratings. Two methacrylate series, a nonpolar HMA-co-HDDMA series and a polar PEGDMA-co-EGDMA series, with significantly different surface wetting properties were evaluated. Equivalent pattern periodicity was maintained across each methacrylate series based on photomask band spacing, and the feature amplitude was tuned to a depth of 2 μm amplitude for all compositions using the temporal control afforded by the UV curing methodology. The surface morphology was characterized by scanning electron microscopy and white light interferometry. All micropatterned films adsorb similar amounts of laminin from solution, and no significant difference in SGN survival was observed when the substrate compositions were compared. SGN neurite alignment significantly increases with increasing material modulus for both methacrylate series. Interestingly, SGN neurites respond to material stiffness cues that are orders of magnitude higher (GPa) than what is typically ascribed to neural environments (kPa). The ability to understand neurite response to engineered physical cues and mechanical properties such as matrix stiffness will allow the development of advanced biomaterials that direct de novo neurite growth to address the spatial signal resolution limitations of current neural prosthetics.
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Affiliation(s)
- Bradley W Tuft
- Department of Chemical and Biochemical Engineering, University of Iowa , Iowa City, Iowa 52242, United States
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40
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Xie Y, Martini N, Hassler C, Kirch RD, Stieglitz T, Seifert A, Hofmann UG. In vivo monitoring of glial scar proliferation on chronically implanted neural electrodes by fiber optical coherence tomography. FRONTIERS IN NEUROENGINEERING 2014; 7:34. [PMID: 25191264 PMCID: PMC4139652 DOI: 10.3389/fneng.2014.00034] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 08/05/2014] [Indexed: 11/14/2022]
Abstract
In neural prosthetics and stereotactic neurosurgery, intracortical electrodes are often utilized for delivering therapeutic electrical pulses, and recording neural electrophysiological signals. Unfortunately, neuroinflammation impairs the neuron-electrode-interface by developing a compact glial encapsulation around the implants in long term. At present, analyzing this immune reaction is only feasible with post-mortem histology; currently no means for specific in vivo monitoring exist and most applicable imaging modalities can not provide information in deep brain regions. Optical coherence tomography (OCT) is a well established imaging modality for in vivo studies, providing cellular resolution and up to 1.2 mm imaging depth in brain tissue. A fiber based spectral domain OCT was shown to be capable of minimally invasive brain imaging. In the present study, we propose to use a fiber based spectral domain OCT to monitor the progression of the tissue's immune response through scar encapsulation progress in a rat animal model. A fine fiber catheter was implanted in rat brain together with a flexible polyimide microelectrode in sight both of which acts as a foreign body and induces the brain tissue immune reaction. OCT signals were collected from animals up to 12 weeks after implantation and thus gliotic scarring in vivo monitored for that time. Preliminary data showed a significant enhancement of the OCT backscattering signal during the first 3 weeks after implantation, and increased attenuation factor of the sampled tissue due to the glial scar formation.
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Affiliation(s)
- Yijing Xie
- Neuroelectronic Systems, Department of General Neurosurgery, University Medical Center Freiburg Freiburg, Germany
| | - Nadja Martini
- Neuroelectronic Systems, Department of General Neurosurgery, University Medical Center Freiburg Freiburg, Germany
| | - Christina Hassler
- Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering(IMTEK), University of Freiburg Freiburg, Germany
| | - Robert D Kirch
- Neuroelectronic Systems, Department of General Neurosurgery, University Medical Center Freiburg Freiburg, Germany
| | - Thomas Stieglitz
- Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering(IMTEK), University of Freiburg Freiburg, Germany
| | - Andreas Seifert
- Gisela and Erwin Sick Chair of Micro-optics, Department of Microsystems Engineering(IMTEK), University of Freiburg Freiburg, Germany
| | - Ulrich G Hofmann
- Neuroelectronic Systems, Department of General Neurosurgery, University Medical Center Freiburg Freiburg, Germany
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Tuft BW, Xu L, White SP, Seline AE, Erwood AM, Hansen MR, Guymon CA. Neural pathfinding on uni- and multidirectional photopolymerized micropatterns. ACS APPLIED MATERIALS & INTERFACES 2014; 6:11265-76. [PMID: 24911660 PMCID: PMC4215840 DOI: 10.1021/am501622a] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 06/09/2014] [Indexed: 05/22/2023]
Abstract
Overcoming signal resolution barriers of neural prostheses, such as the commercially available cochlear impant (CI) or the developing retinal implant, will likely require spatial control of regenerative neural elements. To rationally design materials that direct nerve growth, it is first necessary to determine pathfinding behavior of de novo neurite growth from prosthesis-relevant cells such as spiral ganglion neurons (SGNs) in the inner ear. Accordingly, in this work, repeating 90° turns were fabricated as multidirectional micropatterns to determine SGN neurite turning capability and pathfinding. Unidirectional micropatterns and unpatterned substrates are used as comparisons. Spiral ganglion Schwann cell alignment (SGSC) is also examined on each surface type. Micropatterns are fabricated using the spatial reaction control inherent to photopolymerization with photomasks that have either parallel line spacing gratings for unidirectional patterns or repeating 90° angle steps for multidirectional patterns. Feature depth is controlled by modulating UV exposure time by shuttering the light source at given time increments. Substrate topography is characterized by white light interferometry and scanning electron microscopy (SEM). Both pattern types exhibit features that are 25 μm in width and 7.4 ± 0.7 μm in depth. SGN neurites orient randomly on unpatterned photopolymer controls, align and consistently track unidirectional patterns, and are substantially influenced by, but do not consistently track, multidirectional turning cues. Neurite lengths are 20% shorter on multidirectional substrates compared to unidirectional patterns while neurite branching and microfeature crossing events are significantly higher. For both pattern types, the majority of the neurite length is located in depressed surface features. Developing methods to understand neural pathfinding and to guide de novo neurite growth to specific stimulatory elements will enable design of innovative biomaterials that improve functional outcomes of devices that interface with the nervous system.
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Affiliation(s)
- Bradley W. Tuft
- Department
of Chemical and Biochemical Engineering, University of Iowa, Iowa City, Iowa 52242,
United States, United States
| | - Linjing Xu
- Department
of Otolaryngology, University of Iowa Hospitals
and Clinics, Iowa City, Iowa 52242, United States, United States
| | - Scott P. White
- Department
of Chemical and Biochemical Engineering, University of Iowa, Iowa City, Iowa 52242,
United States, United States
| | - Alison E. Seline
- Department
of Otolaryngology, University of Iowa Hospitals
and Clinics, Iowa City, Iowa 52242, United States, United States
| | - Andrew M. Erwood
- Department
of Otolaryngology, University of Iowa Hospitals
and Clinics, Iowa City, Iowa 52242, United States, United States
| | - Marlan R. Hansen
- Department
of Otolaryngology, University of Iowa Hospitals
and Clinics, Iowa City, Iowa 52242, United States, United States
| | - C. Allan Guymon
- Department
of Chemical and Biochemical Engineering, University of Iowa, Iowa City, Iowa 52242,
United States, United States
- Tel.:(319)335-5015
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Aregueta-Robles UA, Woolley AJ, Poole-Warren LA, Lovell NH, Green RA. Organic electrode coatings for next-generation neural interfaces. FRONTIERS IN NEUROENGINEERING 2014; 7:15. [PMID: 24904405 PMCID: PMC4034607 DOI: 10.3389/fneng.2014.00015] [Citation(s) in RCA: 138] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 05/06/2014] [Indexed: 01/05/2023]
Abstract
Traditional neuronal interfaces utilize metallic electrodes which in recent years have reached a plateau in terms of the ability to provide safe stimulation at high resolution or rather with high densities of microelectrodes with improved spatial selectivity. To achieve higher resolution it has become clear that reducing the size of electrodes is required to enable higher electrode counts from the implant device. The limitations of interfacing electrodes including low charge injection limits, mechanical mismatch and foreign body response can be addressed through the use of organic electrode coatings which typically provide a softer, more roughened surface to enable both improved charge transfer and lower mechanical mismatch with neural tissue. Coating electrodes with conductive polymers or carbon nanotubes offers a substantial increase in charge transfer area compared to conventional platinum electrodes. These organic conductors provide safe electrical stimulation of tissue while avoiding undesirable chemical reactions and cell damage. However, the mechanical properties of conductive polymers are not ideal, as they are quite brittle. Hydrogel polymers present a versatile coating option for electrodes as they can be chemically modified to provide a soft and conductive scaffold. However, the in vivo chronic inflammatory response of these conductive hydrogels remains unknown. A more recent approach proposes tissue engineering the electrode interface through the use of encapsulated neurons within hydrogel coatings. This approach may provide a method for activating tissue at the cellular scale, however, several technological challenges must be addressed to demonstrate feasibility of this innovative idea. The review focuses on the various organic coatings which have been investigated to improve neural interface electrodes.
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Affiliation(s)
| | - Andrew J. Woolley
- Graduate School of Biomedical Engineering, University of New South WalesSydney, NSW, Australia
- School of Medicine, University of Western SydneySydney, NSW, Australia
| | - Laura A. Poole-Warren
- Graduate School of Biomedical Engineering, University of New South WalesSydney, NSW, Australia
| | - Nigel H. Lovell
- Graduate School of Biomedical Engineering, University of New South WalesSydney, NSW, Australia
| | - Rylie A. Green
- Graduate School of Biomedical Engineering, University of New South WalesSydney, NSW, Australia
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Castagnola E, Ansaldo A, Maggiolini E, Ius T, Skrap M, Ricci D, Fadiga L. Smaller, softer, lower-impedance electrodes for human neuroprosthesis: a pragmatic approach. FRONTIERS IN NEUROENGINEERING 2014; 7:8. [PMID: 24795621 PMCID: PMC3997015 DOI: 10.3389/fneng.2014.00008] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 03/29/2014] [Indexed: 12/19/2022]
Abstract
Finding the most appropriate technology for building electrodes to be used for long term implants in humans is a challenging issue. What are the most appropriate technologies? How could one achieve robustness, stability, compatibility, efficacy, and versatility, for both recording and stimulation? There are no easy answers to these questions as even the most fundamental and apparently obvious factors to be taken into account, such as the necessary mechanical, electrical and biological properties, and their interplay, are under debate. We present here our approach along three fundamental parallel pathways: we reduced electrode invasiveness and size without impairing signal-to-noise ratio, we increased electrode active surface area by depositing nanostructured materials, and we protected the brain from direct contact with the electrode without compromising performance. Altogether, these results converge toward high-resolution ECoG arrays that are soft and adaptable to cortical folds, and have been proven to provide high spatial and temporal resolution. This method provides a piece of work which, in our view, makes several steps ahead in bringing such novel devices into clinical settings, opening new avenues in diagnostics of brain diseases, and neuroprosthetic applications.
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Affiliation(s)
- Elisa Castagnola
- Robotics, Brain and Cognitive Sciences Department, Istituto Italiano di Tecnologia Genoa, Italy
| | - Alberto Ansaldo
- Robotics, Brain and Cognitive Sciences Department, Istituto Italiano di Tecnologia Genoa, Italy
| | - Emma Maggiolini
- Robotics, Brain and Cognitive Sciences Department, Istituto Italiano di Tecnologia Genoa, Italy
| | - Tamara Ius
- Struttura Complessa di Neurochirurgia, Azienda Ospedaliero-Universitaria Santa Maria della Misericordia Udine, Italy
| | - Miran Skrap
- Struttura Complessa di Neurochirurgia, Azienda Ospedaliero-Universitaria Santa Maria della Misericordia Udine, Italy
| | - Davide Ricci
- Robotics, Brain and Cognitive Sciences Department, Istituto Italiano di Tecnologia Genoa, Italy
| | - Luciano Fadiga
- Robotics, Brain and Cognitive Sciences Department, Istituto Italiano di Tecnologia Genoa, Italy ; Section of Human Physiology, Department of Biomedical Sciences, University of Ferrara Ferrara, Italy
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Fattahi P, Yang G, Kim G, Abidian MR. A review of organic and inorganic biomaterials for neural interfaces. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2014; 26:1846-85. [PMID: 24677434 PMCID: PMC4373558 DOI: 10.1002/adma.201304496] [Citation(s) in RCA: 300] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 10/08/2013] [Indexed: 05/18/2023]
Abstract
Recent advances in nanotechnology have generated wide interest in applying nanomaterials for neural prostheses. An ideal neural interface should create seamless integration into the nervous system and performs reliably for long periods of time. As a result, many nanoscale materials not originally developed for neural interfaces become attractive candidates to detect neural signals and stimulate neurons. In this comprehensive review, an overview of state-of-the-art microelectrode technologies provided fi rst, with focus on the material properties of these microdevices. The advancements in electro active nanomaterials are then reviewed, including conducting polymers, carbon nanotubes, graphene, silicon nanowires, and hybrid organic-inorganic nanomaterials, for neural recording, stimulation, and growth. Finally, technical and scientific challenges are discussed regarding biocompatibility, mechanical mismatch, and electrical properties faced by these nanomaterials for the development of long-lasting functional neural interfaces.
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Affiliation(s)
- Pouria Fattahi
- Biomedical Engineering Department and Chemical Engineering Departments, Pennsylvania State University, University Park, PA, 16802, USA
| | - Guang Yang
- Biomedical Engineering Department, Pennsylvania State University, University Park, PA, 16802, USA
| | - Gloria Kim
- Biomedical Engineering Department, Pennsylvania State University, University Park, PA, 16802, USA
| | - Mohammad Reza Abidian
- Biomedical Engineering Department, Materials Science & Engineering Department, Chemical Engineering Department, Materials Research Institute, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, 16802, USA
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Richter A, Xie Y, Schumacher A, Löffler S, Kirch RD, Al-Hasani J, Rapoport DH, Kruse C, Moser A, Tronnier V, Danner S, Hofmann UG. A simple implantation method for flexible, multisite microelectrodes into rat brains. FRONTIERS IN NEUROENGINEERING 2013; 6:6. [PMID: 23898266 PMCID: PMC3721086 DOI: 10.3389/fneng.2013.00006] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 07/02/2013] [Indexed: 11/18/2022]
Abstract
A long term functional and reliable coupling between neural tissue and implanted microelectrodes is the key issue in acquiring neural electrophysiological signals or therapeutically excite neural tissue. The currently often used rigid micro-electrodes are thought to cause a severe foreign body reaction resulting in a thick glial scar and consequently a poor tissue-electrode coupling in the chronic phase. We hypothesize, that this adverse effect might be remedied by probes compliant to the soft brain tissue, i.e., replacing rigid electrodes by flexible ones. Unfortunately, this flexibility comes at the price of a low stiffness, which makes targeted low trauma implantation very challenging. In this study, we demonstrate an adaptable and simple method to implant extremely flexible microprobes even to deep areas of rat's brain. Implantation of flexible probes is achieved by rod supported stereotactic insertion fostered by a hydrogel (2% agarose in PBS) cushion on the exposed skull. We were thus able to implant very flexible micro-probes in 70 rats as deep as the rodent's subthalamic nucleus. This work describes in detail the procedures and steps needed for minimal invasive, but reliable implantation of flexible probes.
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Affiliation(s)
- Anja Richter
- Neurochemistry Group, Department of Neurology, University of Luebeck Luebeck, Germany
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Woolley AJ, Desai HA, Otto KJ. Chronic intracortical microelectrode arrays induce non-uniform, depth-related tissue responses. J Neural Eng 2013; 10:026007. [PMID: 23428842 DOI: 10.1088/1741-2560/10/2/026007] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Brain-implanted microelectrode arrays show promise as future clinical devices. However, biological responses to various designs, compositions and locations of these implants have not been fully characterized, and may impact the long-term functionality of these devices. In order to improve our understanding of the tissue conditions at the interface of chronic brain-implanted microdevices, we proposed utilizing advanced histology and microscopy techniques to image implanted devices and surrounding tissue intact within brain slices. We then proposed utilizing these methods to examine whether depth within the cerebral cortex affected tissue conditions around implants. APPROACH Histological data was collected from rodent brain slices containing intact, intracortical microdevices four weeks after implantation surgery. Thick tissue sections containing the chronic implants were processed with fluorescent antibody labels, and imaged in an optical clearing solution using laser confocal microscopy. MAIN RESULTS Tissue surrounding microdevices exhibited two major depth-related phenomena: a non-uniform microglial coating along the device length and a dense mass of cells surrounding the implant in cerebral cortical layers I and II. Detailed views of the monocyte-derived immune cells improve our understanding of the close and complex association that immune cells have with chronic brain implants, and illuminated a possible relationship between cortical depth and the intensity of a chronic monocyte response around penetrating microdevices. The dense mass of cells contained vimentin, a protein not typically expressed highly in CNS cells, evidence that non-CNS cells likely descended down the face of the penetrating devices from the pial surface. SIGNIFICANCE Image data of highly non-uniform and depth-dependent biological responses along a device provides novel insight into the complexity of the tissue response to penetrating brain-implanted microdevices. The presented work also demonstrates the value of in situ histological collection of brain implants for studying the complex tissue changes that occur, and the utility of pairing thick-tissue histology with appropriate optical clearing solutions.
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Affiliation(s)
- Andrew J Woolley
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907-2032, USA.
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48
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Photopolymerized microfeatures for directed spiral ganglion neurite and Schwann cell growth. Biomaterials 2012; 34:42-54. [PMID: 23069708 DOI: 10.1016/j.biomaterials.2012.09.053] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 09/23/2012] [Indexed: 12/15/2022]
Abstract
Cochlear implants (CIs) provide auditory perception to individuals with severe hearing impairment. However, their ability to encode complex auditory stimuli is limited due, in part, to poor spatial resolution caused by electrical current spread in the inner ear. Directing nerve cell processes towards target electrodes may reduce the problematic current spread and improve stimulatory specificity. In this work, photopolymerization was used to fabricate micro- and nano-patterned methacrylate polymers to probe the extent of spiral ganglion neuron (SGN) neurite and Schwann cell (SGSC) contact guidance based on variations in substrate topographical cues. Micropatterned substrates are formed in a rapid, single-step reaction by selectively blocking light with photomasks which have parallel line-space gratings with periodicities of 10-100 μm. Channel amplitudes of 250 nm-10 μm are generated by modulating UV exposure time, light intensity, and photoinitiator concentration. Gradual transitions are observed between ridges and grooves using scanning electron and atomic force microscopy. The transitions stand in contrast to vertical features generated via etching lithographic techniques. Alignment of neural elements increases significantly with increasing feature amplitude and constant periodicity, as well as with decreasing periodicity and constant amplitude. SGN neurite alignment strongly correlates (r = 0.93) with maximum feature slope. Multiple neuronal and glial types orient to the patterns with varying degrees of alignment. This work presents a method to fabricate gradually-sloping micropatterns for cellular contact guidance studies and demonstrates spatial control of inner ear neural elements in response to micro- and nano-scale surface topography.
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Potter KA, Buck AC, Self WK, Capadona JR. Stab injury and device implantation within the brain results in inversely multiphasic neuroinflammatory and neurodegenerative responses. J Neural Eng 2012; 9:046020. [PMID: 22832283 DOI: 10.1088/1741-2560/9/4/046020] [Citation(s) in RCA: 167] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
An estimated 25 million people in the US alone rely on implanted medical devices, ∼2.5 million implanted within the nervous system. Even though many devices perform adequately for years, the host response to medical devices often severely limits tissue integration and long-term performance. This host response is believed to be particularly limiting in the case of intracortical microelectrodes, where it has been shown that glial cell encapsulation and localized neuronal cell loss accompany intracortical microelectrode implantation. Since neuronal ensembles must be within ∼50 µm of the electrode to obtain neuronal spikes and local field potentials, developing a better understanding of the molecular and cellular environment at the device-tissue interface has been the subject of significant research. Unfortunately, immunohistochemical studies of scar maturation in correlation to device function have been inconclusive. Therefore, here we present a detailed quantitative study of the cellular events and the stability of the blood-brain barrier (BBB) following intracortical microelectrode implantation and cortical stab injury in a chronic survival model. We found two distinctly inverse multiphasic profiles for neuronal survival in device-implanted tissue compared to stab-injured animals. For chronically implanted animals, we observed a biphasic paradigm between blood-derived/trauma-induced and CNS-derived inflammatory markers driving neurodegeneration at the interface. In contrast, stab injured animals demonstrated a CNS-mediated neurodegenerative environment. Collectively these data provide valuable insight to the possibility of multiple roles of chronic neuroinflammatory events on BBB disruption and localized neurodegeneration, while also suggesting the importance to consider multiphasic neuroinflammatory kinetics in the design of therapeutic strategies for stabilizing neural interfaces.
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Affiliation(s)
- Kelsey A Potter
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
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Martinez Y, Dubois-Dauphin M, Krause KH. Generation and applications of human pluripotent stem cells induced into neural lineages and neural tissues. Front Physiol 2012; 3:47. [PMID: 22457650 PMCID: PMC3307166 DOI: 10.3389/fphys.2012.00047] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 02/21/2012] [Indexed: 01/01/2023] Open
Abstract
Human pluripotent stem cells (hPSCs) represent a new and exciting field in modern medicine, now the focus of many researchers and media outlets. The hype is well-earned because of the potential of stem cells to contribute to disease modeling, drug screening, and even therapeutic approaches. In this review, we focus first on neural differentiation of these cells. In a second part we compare the various cell types available and their advantages for in vitro modeling. Then we provide a “state-of-the-art” report about two major biomedical applications: (1) the drug and toxicity screening and (2) the neural tissue replacement. Finally, we made an overview about current biomedical research using differentiated hPSCs.
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Affiliation(s)
- Y Martinez
- Department of Pathology and Immunology, Faculty of Medicine, University of Geneva Geneva, Switzerland
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