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Kiang L, Woodington B, Carnicer-Lombarte A, Malliaras G, Barone DG. Spinal cord bioelectronic interfaces: opportunities in neural recording and clinical challenges. J Neural Eng 2022; 19. [PMID: 35320780 DOI: 10.1088/1741-2552/ac605f] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 03/23/2022] [Indexed: 11/11/2022]
Abstract
Bioelectronic stimulation of the spinal cord has demonstrated significant progress in restoration of motor function in spinal cord injury (SCI). The proximal, uninjured spinal cord presents a viable target for the recording and generation of control signals to drive targeted stimulation. Signals have been directly recorded from the spinal cord in behaving animals and correlated with limb kinematics. Advances in flexible materials, electrode impedance and signal analysis will allow SCR to be used in next-generation neuroprosthetics. In this review, we summarize the technological advances enabling progress in SCR and describe systematically the clinical challenges facing spinal cord bioelectronic interfaces and potential solutions, from device manufacture, surgical implantation to chronic effects of foreign body reaction and stress-strain mismatches between electrodes and neural tissue. Finally, we establish our vision of bi-directional closed-loop spinal cord bioelectronic bypass interfaces that enable the communication of disrupted sensory signals and restoration of motor function in SCI.
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Affiliation(s)
- Lei Kiang
- Orthopaedic Surgery, Singapore General Hospital, Outram Road, Singapore, Singapore, 169608, SINGAPORE
| | - Ben Woodington
- Department of Engineering, University of Cambridge, Electrical Engineering Division, 9 JJ Thomson Ave, Cambridge, Cambridge, CB2 1TN, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Alejandro Carnicer-Lombarte
- Clinical Neurosciences, University of Cambridge, Bioelectronics Laboratory, Cambridge, CB2 0PY, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - George Malliaras
- University of Cambridge, University of Cambridge, Cambridge, CB2 1TN, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Damiano G Barone
- Department of Engineering, University of Cambridge, Electrical Engineering Division, 9 JJ Thomson Ave, Cambridge, Cambridge, Cambridgeshire, CB2 1TN, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
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2
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Cho Y, Lee M, Park S, Kim Y, Lee E, Im SG. A Versatile Surface Modification Method via Vapor-phase Deposited Functional Polymer Films for Biomedical Device Applications. BIOTECHNOL BIOPROC E 2021; 26:165-178. [PMID: 33821132 PMCID: PMC8013202 DOI: 10.1007/s12257-020-0269-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 10/05/2020] [Accepted: 10/08/2020] [Indexed: 01/01/2023]
Abstract
For last two decades, the demand for precisely engineered three-dimensional structures has increased continuously for the developments of biomaterials. With the recent advances in micro- and nano-fabrication techniques, various devices with complex surface geometries have been devised and produced in the pharmaceutical and medical fields for various biomedical applications including drug delivery and biosensors. These advanced biomaterials have been designed to mimic the natural environments of tissues more closely and to enhance the performance for their corresponding biomedical applications. One of the important aspects in the rational design of biomaterials is how to configure the surface of the biomedical devices for better control of the chemical and physical properties of the bioactive surfaces without compromising their bulk characteristics. In this viewpoint, it of critical importance to secure a versatile method to modify the surface of various biomedical devices. Recently, a vapor phase method, termed initiated chemical vapor deposition (iCVD) has emerged as damage-free method highly beneficial for the conformal deposition of various functional polymer films onto many kinds of micro- and nano-structured surfaces without restrictions on the substrate material or geometry, which is not trivial to achieve by conventional solution-based surface functionalization methods. With proper structural design, the functional polymer thin film via iCVD can impart required functionality to the biomaterial surfaces while maintaining the fine structure thereon. We believe the iCVD technique can be not only a valuable approach towards fundamental cell-material studies, but also of great importance as a platform technology to extend to other prospective biomaterial designs and material interface modifications for biomedical applications.
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Affiliation(s)
- Younghak Cho
- Department of Chemical and Biomolecular Engineering, Korea Advanced of Institute of Science and Technology, Daejeon, 34141 Korea
| | - Minseok Lee
- Department of Chemical and Biomolecular Engineering, Korea Advanced of Institute of Science and Technology, Daejeon, 34141 Korea
| | - Seonghyeon Park
- Department of Chemical and Biomolecular Engineering, Korea Advanced of Institute of Science and Technology, Daejeon, 34141 Korea
| | - Yesol Kim
- Department of Chemical and Biomolecular Engineering, Korea Advanced of Institute of Science and Technology, Daejeon, 34141 Korea
| | - Eunjung Lee
- Department of Chemical and Biomolecular Engineering, Korea Advanced of Institute of Science and Technology, Daejeon, 34141 Korea
| | - Sung Gap Im
- Department of Chemical and Biomolecular Engineering, Korea Advanced of Institute of Science and Technology, Daejeon, 34141 Korea
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3
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Ashurbekova K, Ashurbekova K, Saric I, Modin E, Petravic M, Abdulagatov I, Abdulagatov A, Knez M. Radical-triggered cross-linking for molecular layer deposition of SiAlCOH hybrid thin films. Chem Commun (Camb) 2021; 57:2160-2163. [PMID: 33523070 DOI: 10.1039/d0cc07858a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Here, we report on a simultaneous growth and radical-initiated cross-linking of a hybrid thin film in a layer-by-layer manner via molecular layer deposition (MLD). The cross-linked film exhibited a self-limiting MLD growth behavior and improved properties like 12% higher film density and enhanced stability compared to the non-cross-linked film.
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4
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Khlyustova A, Cheng Y, Yang R. Vapor-deposited functional polymer thin films in biological applications. J Mater Chem B 2020; 8:6588-6609. [PMID: 32756662 PMCID: PMC7429282 DOI: 10.1039/d0tb00681e] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Functional polymer coatings have become ubiquitous in biological applications, ranging from biomaterials and drug delivery to manufacturing-scale separation of biomolecules using functional membranes. Recent advances in the technology of chemical vapor deposition (CVD) have enabled precise control of the polymer chemistry, coating thickness, and conformality. That comprehensive control of surface properties has been used to elicit desirable interactions at the interface between synthetic materials and living organisms, making vapor-deposited functional polymers uniquely suitable for biological applications. This review captures the recent technological development in vapor-deposited functional polymer coatings, highlighting their biological applications, including membrane-based bio-separations, biosensing and bio-MEMS, drug delivery, and tissue engineering. The conformal nature of vapor-deposited coatings ensures uniform coverage over micro- and nano-structured surfaces, allowing the independent optimization of surface and bulk properties. The substrate-independence of CVD techniques enables facile transfer of surface characteristics among different applications. The vapor-deposited functional polymer thin films tend to be biocompatible because they are free of remnant toxic solvents and precursor molecules, potentially lowering the barrier to clinical success.
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Affiliation(s)
- Alexandra Khlyustova
- Robert F. Smith School of Chemical & Biomolecular Engineering, Cornell University, Ithaca, New York 14850, USA.
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5
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Ashurbekova K, Ashurbekova K, Saric I, Modin E, Petravić M, Abdulagatov I, Abdulagatov A, Knez M. Molecular layer deposition of hybrid siloxane thin films by ring opening of cyclic trisiloxane (V 3D 3) and azasilane. Chem Commun (Camb) 2020; 56:8778-8781. [PMID: 32618293 DOI: 10.1039/d0cc04195e] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
In this work, we report the first ring opening vapor to solid polymerization of cyclotrisiloxane and N-methyl-aza-2,2,4-trimethylsilacyclopentane by molecular layer deposition (MLD). This process was studied in situ with a quartz crystal microbalance and the thin film was characterized by X-ray photoelectron spectroscopy, ATR-FTIR and high-resolution transmission electron microscopy.
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Affiliation(s)
| | | | - Iva Saric
- Department of Physics and Centre for Micro- and Nanosciences and Technologies, University of Rijeka, 51000 Rijeka, Croatia
| | | | - Mladen Petravić
- Department of Physics and Centre for Micro- and Nanosciences and Technologies, University of Rijeka, 51000 Rijeka, Croatia
| | | | - Aziz Abdulagatov
- Dagestan State University, Makhachkala 36700, Russian Federation.
| | - Mato Knez
- CIC nanoGUNE, 20018 San Sebastian, Spain. and Department of Physics and Centre for Micro- and Nanosciences and Technologies, University of Rijeka, 51000 Rijeka, Croatia and IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain
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Gulino M, Kim D, Pané S, Santos SD, Pêgo AP. Tissue Response to Neural Implants: The Use of Model Systems Toward New Design Solutions of Implantable Microelectrodes. Front Neurosci 2019; 13:689. [PMID: 31333407 PMCID: PMC6624471 DOI: 10.3389/fnins.2019.00689] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 06/18/2019] [Indexed: 01/28/2023] Open
Abstract
The development of implantable neuroelectrodes is advancing rapidly as these tools are becoming increasingly ubiquitous in clinical practice, especially for the treatment of traumatic and neurodegenerative disorders. Electrodes have been exploited in a wide number of neural interface devices, such as deep brain stimulation, which is one of the most successful therapies with proven efficacy in the treatment of diseases like Parkinson or epilepsy. However, one of the main caveats related to the clinical application of electrodes is the nervous tissue response at the injury site, characterized by a cascade of inflammatory events, which culminate in chronic inflammation, and, in turn, result in the failure of the implant over extended periods of time. To overcome current limitations of the most widespread macroelectrode based systems, new design strategies and the development of innovative materials with superior biocompatibility characteristics are currently being investigated. This review describes the current state of the art of in vitro, ex vivo, and in vivo models available for the study of neural tissue response to implantable microelectrodes. We particularly highlight new models with increased complexity that closely mimic in vivo scenarios and that can serve as promising alternatives to animal studies for investigation of microelectrodes in neural tissues. Additionally, we also express our view on the impact of the progress in the field of neural tissue engineering on neural implant research.
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Affiliation(s)
- Maurizio Gulino
- i3S – Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- INEB – Instituto de Engenharia Biomédica, Universidade do Porto, Porto, Portugal
- FEUP – Faculdade de Engenharia, Universidade do Porto, Porto, Portugal
| | - Donghoon Kim
- Multi-Scale Robotics Lab (MSRL), Institute of Robotics and Intelligent Systems (IRIS), ETH Zurich, Zurich, Switzerland
| | - Salvador Pané
- Multi-Scale Robotics Lab (MSRL), Institute of Robotics and Intelligent Systems (IRIS), ETH Zurich, Zurich, Switzerland
| | - Sofia Duque Santos
- i3S – Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- INEB – Instituto de Engenharia Biomédica, Universidade do Porto, Porto, Portugal
| | - Ana Paula Pêgo
- i3S – Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- INEB – Instituto de Engenharia Biomédica, Universidade do Porto, Porto, Portugal
- FEUP – Faculdade de Engenharia, Universidade do Porto, Porto, Portugal
- ICBAS – Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
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7
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Black BJ, Ecker M, Stiller A, Rihani R, Danda VR, Reed I, Voit WE, Pancrazio JJ. In vitro compatibility testing of thiol-ene/acrylate-based shape memory polymers for use in implantable neural interfaces. J Biomed Mater Res A 2018; 106:2891-2898. [PMID: 30371968 DOI: 10.1002/jbm.a.36478] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2017] [Revised: 05/06/2018] [Accepted: 05/24/2018] [Indexed: 12/26/2022]
Abstract
Shape memory polymers (SMPs) based on thiol-ene/acrylate formulations are an emerging class of materials with potential applications as structural and/or dielectric coatings for implantable neural interfaces. Here, we report in vitro compatibility studies of three novel thiol-ene/acrylate-based SMP formulations. In vivo cytotoxicity assays were carried out in accordance with International Organization for Standards (ISO) protocol 10993-5, using NCTC clone 929 fibroblasts as well as embryonic cortical cultures. All three SMP formulations passed standardized cytotoxicity assays (>70% normalized cell viability) using both cell types. Functional neurotoxicity assays were carried out using primary cortical networks cultured on substrate-integrated microelectrode arrays (MEAs). We observed significant reduction in cortical network activity in the case of positive control material, but no significant alterations in activity following incubation with SMP material extracts, indicating functional cytocompatibility. Finally, we assessed cell reactivity at the tissue-material interface by performing an in vitro glial scarring assay. Through immunostaining, we observed similar astrocyte-associated (GFAP) mean intensity ratios near nonsoftening SMP-coated and uncoated stainless steel microwires (1.10 ± 0.06 vs. 1.19 ± 0.10), suggesting similar glial cell reactivity. However, we observed decreased mean intensity ratios in the presence of fully softening SMP-coated microwires (1.02 ± 0.04) suggesting reduced glial cell reactivity. Overall, these results indicate that the thiol-ene/acrylate SMP formulations presented here are neither cytotoxic nor neurotoxic, and suggest that fully softening SMP may reduce foreign body response in terms of glial cell reactivity. These findings support further consideration of this class of materials as backbone or insulating materials for implantable neural stimulating/recording devices. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2891-2898, 2018.
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Affiliation(s)
- Bryan J Black
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Road, Bioengineering and Sciences Building 13.633, Richardson, Texas, 75080
| | - Melanie Ecker
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Road, Bioengineering and Sciences Building 13.633, Richardson, Texas, 75080
| | - Allison Stiller
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Road, Bioengineering and Sciences Building 13.633, Richardson, Texas, 75080
| | - Rashed Rihani
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Road, Bioengineering and Sciences Building 13.633, Richardson, Texas, 75080
| | - Vindhya Reddy Danda
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Road, Bioengineering and Sciences Building 13.633, Richardson, Texas, 75080
| | - Isabella Reed
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Road, Bioengineering and Sciences Building 13.633, Richardson, Texas, 75080
| | - Walter E Voit
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Road, Bioengineering and Sciences Building 13.633, Richardson, Texas, 75080
| | - Joseph J Pancrazio
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Road, Bioengineering and Sciences Building 13.633, Richardson, Texas, 75080
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8
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Wellman SM, Eles JR, Ludwig KA, Seymour JP, Michelson NJ, McFadden WE, Vazquez AL, Kozai TDY. A Materials Roadmap to Functional Neural Interface Design. ADVANCED FUNCTIONAL MATERIALS 2018; 28:1701269. [PMID: 29805350 PMCID: PMC5963731 DOI: 10.1002/adfm.201701269] [Citation(s) in RCA: 186] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Advancement in neurotechnologies for electrophysiology, neurochemical sensing, neuromodulation, and optogenetics are revolutionizing scientific understanding of the brain while enabling treatments, cures, and preventative measures for a variety of neurological disorders. The grand challenge in neural interface engineering is to seamlessly integrate the interface between neurobiology and engineered technology, to record from and modulate neurons over chronic timescales. However, the biological inflammatory response to implants, neural degeneration, and long-term material stability diminish the quality of interface overtime. Recent advances in functional materials have been aimed at engineering solutions for chronic neural interfaces. Yet, the development and deployment of neural interfaces designed from novel materials have introduced new challenges that have largely avoided being addressed. Many engineering efforts that solely focus on optimizing individual probe design parameters, such as softness or flexibility, downplay critical multi-dimensional interactions between different physical properties of the device that contribute to overall performance and biocompatibility. Moreover, the use of these new materials present substantial new difficulties that must be addressed before regulatory approval for use in human patients will be achievable. In this review, the interdependence of different electrode components are highlighted to demonstrate the current materials-based challenges facing the field of neural interface engineering.
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Affiliation(s)
- Steven M Wellman
- Department of Bioengineering, Center for the Basis of Neural Cognition, McGowan Institute of Regenerative Medicine, NeuroTech Center, University of Pittsburgh Brain Institute, Center for Neuroscience at the University of Pittsburgh, University of Pittsburgh, 208 Center for Biotechnology, 300 Technology Dr., Pittsburgh, PA 15219, United States
| | - James R Eles
- Department of Bioengineering, Center for the Basis of Neural Cognition, McGowan Institute of Regenerative Medicine, NeuroTech Center, University of Pittsburgh Brain Institute, Center for Neuroscience at the University of Pittsburgh, University of Pittsburgh, 208 Center for Biotechnology, 300 Technology Dr., Pittsburgh, PA 15219, United States
| | - Kip A Ludwig
- Department of Neurologic Surgery, 200 First St. SW, Rochester, MN 55905
| | - John P Seymour
- Electrical & Computer Engineering, 1301 Beal Ave., 2227 EECS, Ann Arbor, MI 48109
| | - Nicholas J Michelson
- Department of Bioengineering, Center for the Basis of Neural Cognition, McGowan Institute of Regenerative Medicine, NeuroTech Center, University of Pittsburgh Brain Institute, Center for Neuroscience at the University of Pittsburgh, University of Pittsburgh, 208 Center for Biotechnology, 300 Technology Dr., Pittsburgh, PA 15219, United States
| | - William E McFadden
- Department of Bioengineering, Center for the Basis of Neural Cognition, McGowan Institute of Regenerative Medicine, NeuroTech Center, University of Pittsburgh Brain Institute, Center for Neuroscience at the University of Pittsburgh, University of Pittsburgh, 208 Center for Biotechnology, 300 Technology Dr., Pittsburgh, PA 15219, United States
| | - Alberto L Vazquez
- Department of Bioengineering, Center for the Basis of Neural Cognition, McGowan Institute of Regenerative Medicine, NeuroTech Center, University of Pittsburgh Brain Institute, Center for Neuroscience at the University of Pittsburgh, University of Pittsburgh, 208 Center for Biotechnology, 300 Technology Dr., Pittsburgh, PA 15219, United States
| | - Takashi D Y Kozai
- Department of Bioengineering, Center for the Basis of Neural Cognition, McGowan Institute of Regenerative Medicine, NeuroTech Center, University of Pittsburgh Brain Institute, Center for Neuroscience at the University of Pittsburgh, University of Pittsburgh, 208 Center for Biotechnology, 300 Technology Dr., Pittsburgh, PA 15219, United States
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Gilmour AD, Woolley AJ, Poole-Warren LA, Thomson CE, Green RA. A critical review of cell culture strategies for modelling intracortical brain implant material reactions. Biomaterials 2016; 91:23-43. [PMID: 26994876 DOI: 10.1016/j.biomaterials.2016.03.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 02/29/2016] [Accepted: 03/06/2016] [Indexed: 02/07/2023]
Abstract
The capacity to predict in vivo responses to medical devices in humans currently relies greatly on implantation in animal models. Researchers have been striving to develop in vitro techniques that can overcome the limitations associated with in vivo approaches. This review focuses on a critical analysis of the major in vitro strategies being utilized in laboratories around the world to improve understanding of the biological performance of intracortical, brain-implanted microdevices. Of particular interest to the current review are in vitro models for studying cell responses to penetrating intracortical devices and their materials, such as electrode arrays used for brain computer interface (BCI) and deep brain stimulation electrode probes implanted through the cortex. A background on the neural interface challenge is presented, followed by discussion of relevant in vitro culture strategies and their advantages and disadvantages. Future development of 2D culture models that exhibit developmental changes capable of mimicking normal, postnatal development will form the basis for more complex accurate predictive models in the future. Although not within the scope of this review, innovations in 3D scaffold technologies and microfluidic constructs will further improve the utility of in vitro approaches.
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Affiliation(s)
- A D Gilmour
- Graduate School of Biomedical Engineering, The University of New South Wales, Sydney, NSW 2052, Australia.
| | - A J Woolley
- Graduate School of Biomedical Engineering, The University of New South Wales, Sydney, NSW 2052, Australia; Western Sydney University, Sydney, NSW, Australia
| | - L A Poole-Warren
- Graduate School of Biomedical Engineering, The University of New South Wales, Sydney, NSW 2052, Australia
| | - C E Thomson
- Department of Veterinary Medicine, University of Alaska, Fairbanks, AK 99775, USA
| | - R A Green
- Graduate School of Biomedical Engineering, The University of New South Wales, Sydney, NSW 2052, Australia
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10
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Lee JY, Khaing ZZ, Siegel JJ, Schmidt CE. Surface modification of neural electrodes with pyrrole-hyaluronic acid conjugate to attenuate reactive astrogliosis in vivo. RSC Adv 2015; 5:39228-39231. [PMID: 35528963 PMCID: PMC9075707 DOI: 10.1039/c5ra03294f] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/04/2023] Open
Abstract
Surface of neural probes were electrochemically modified with a non-cell adhesive and biocompatible conjugate, pyrrole-hyaluronic acid (PyHA), to reduce reactive astrogliosis. Poly(PyHA)-modified wire electrodes were implanted into rat motor cortices for three weeks and were found to markedly reduce the expression of glial fibrillary acidic protein compared to uncoated electrodes.
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Affiliation(s)
- J Y Lee
- Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, USA
- School of Materials Science and Engineering, Gwangju Institute of Science and Engineering, Gwangju, South Korea
| | - Z Z Khaing
- Department of Biomedical Engineering, The University of Florida at Gainesville, Gainesville, FL, USA
| | - J J Siegel
- Center for Learning and Memory, The University of Texas at Austin, Austin, TX, USA
| | - C E Schmidt
- Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, USA
- Department of Biomedical Engineering, The University of Florida at Gainesville, Gainesville, FL, USA
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11
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Nebulized solvent ablation of aligned PLLA fibers for the study of neurite response to anisotropic-to-isotropic fiber/film transition (AFFT) boundaries in astrocyte-neuron co-cultures. Biomaterials 2015; 46:82-94. [PMID: 25678118 DOI: 10.1016/j.biomaterials.2014.12.046] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 12/01/2014] [Accepted: 12/16/2014] [Indexed: 12/18/2022]
Abstract
Developing robust in vitro models of in vivo environments has the potential to reduce costs and bring new therapies from the bench top to the clinic more efficiently. This study aimed to develop a biomaterial platform capable of modeling isotropic-to-anisotropic cellular transitions observed in vivo, specifically focusing on changes in cellular organization following spinal cord injury. In order to accomplish this goal, nebulized solvent patterning of aligned, electrospun poly-l-lactic acid (PLLA) fiber substrates was developed. This method produced a clear topographic transitional boundary between aligned PLLA fibers and an isotropic PLLA film region. Astrocytes were then seeded on these scaffolds, and a shift between oriented and non-oriented astrocytes was created at the anisotropic-to-isotropic fiber/film transition (AFFT) boundary. Orientation of chondroitin sulfate proteoglycans (CSPGs) and fibronectin produced by these astrocytes was analyzed, and it was found that astrocytes growing on the aligned fibers produced aligned arrays of CSPGs and fibronectin, while astrocytes growing on the isotropic film region produced randomly-oriented CSPG and fibronectin arrays. Neurite extension from rat dissociated dorsal root ganglia (DRG) was studied on astrocytes cultured on anisotropic, aligned fibers, isotropic films, or from fibers to films. It was found that neurite extension was oriented and longer on PLLA fibers compared to PLLA films. When dissociated DRG were cultured on the astrocytes near the AFFT boundary, neurites showed directed orientation that was lost upon growth into the isotropic film region. The AFFT boundary also restricted neurite extension, limiting the extension of neurites once they grew from the fibers and into the isotropic film region. This study reveals the importance of anisotropic-to-isotropic transitions restricting neurite outgrowth by itself. Furthermore, we present this scaffold as an alternative culture system to analyze neurite response to cellular boundaries created following spinal cord injury and suggest its usefulness to study cellular responses to any aligned-to-unorganized cellular boundaries seen in vivo.
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12
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Sommakia S, Rickus JL, Otto KJ. Glial cells, but not neurons, exhibit a controllable response to a localized inflammatory microenvironment in vitro. FRONTIERS IN NEUROENGINEERING 2014; 7:41. [PMID: 25452724 PMCID: PMC4231942 DOI: 10.3389/fneng.2014.00041] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 10/28/2014] [Indexed: 11/13/2022]
Abstract
The ability to design long-lasting intracortical implants hinges on understanding the factors leading to the loss of neuronal density and the formation of the glial scar. In this study, we modify a common in vitro mixed cortical culture model using lipopolysaccharide (LPS) to examine the responses of microglia, astrocytes, and neurons to microwire segments. We also use dip-coated polyethylene glycol (PEG), which we have previously shown can modulate impedance changes to neural microelectrodes, to control the cellular responses. We find that microglia, as expected, exhibit an elevated response to LPS-coated microwire for distances of up to 150 μm, and that this elevated response can be mitigated by co-depositing PEG with LPS. Astrocytes exhibit a more complex, distance-dependent response, whereas neurons do not appear to be affected by the type or magnitude of glial response within this in vitro model. The discrepancy between our in vitro responses and typically observed in vivo responses suggest the importance of using a systems approach to understand the responses of the various brain cell types in a chronic in vivo setting, as well as the necessity of studying the roles of cell types not native to the brain. Our results further indicate that the loss of neuronal density observed in vivo is not a necessary consequence of elevated glial activation.
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Affiliation(s)
- Salah Sommakia
- Weldon School of Biomedical Engineering, Purdue University West Lafayette, IN, USA ; Physiological Sensing Facility at the Bindley Bioscience Center and Birck Nanotechnology Center, Purdue University West Lafayette, IN, USA
| | - Jenna L Rickus
- Weldon School of Biomedical Engineering, Purdue University West Lafayette, IN, USA ; Physiological Sensing Facility at the Bindley Bioscience Center and Birck Nanotechnology Center, Purdue University West Lafayette, IN, USA ; Department of Agricultural and Biological Engineering, Purdue University West Lafayette, IN, USA
| | - Kevin J Otto
- Weldon School of Biomedical Engineering, Purdue University West Lafayette, IN, USA ; Department of Biological Sciences, Purdue University West Lafayette, IN, USA ; J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida Gainesville, FL, USA
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13
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Ereifej ES, Khan S, Newaz G, Zhang J, Auner GW, VandeVord PJ. Comparative assessment of iridium oxide and platinum alloy wires using an in vitro glial scar assay. Biomed Microdevices 2014; 15:917-24. [PMID: 23764951 DOI: 10.1007/s10544-013-9780-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The long-term effect of chronically implanted electrodes is the formation of a glial scar. Therefore, it is imperative to assess the biocompatibility of materials before employing them in neural electrode fabrication. Platinum alloy and iridium oxide have been identified as good candidates as neural electrode biomaterials due to their mechanical and electrical properties, however, effect of glial scar formation for these two materials is lacking. In this study, we applied a glial scarring assay to observe the cellular reactivity to platinum alloy and iridium oxide wires in order to assess the biocompatibility based on previously defined characteristics. Through real-time PCR, immunostaining and imaging techniques, we will advance the understanding of the biocompatibility of these materials. Results of this study demonstrate iridium oxide wires exhibited a more significant reactive response as compared to platinum alloy wires. Cells cultured with platinum alloy wires had less GFAP gene expression, lower average GFAP intensity, and smaller glial scar thickness. Collectively, these results indicated that platinum alloy wires were more biocompatible than the iridium oxide wires.
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Affiliation(s)
- Evon S Ereifej
- Department of Biomedical Engineering, Wayne State University, Detroit, MI, USA
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Ware T, Simon D, Liu C, Musa T, Vasudevan S, Sloan A, Keefer EW, Rennaker RL, Voit W. Thiol-ene/acrylate substrates for softening intracortical electrodes. J Biomed Mater Res B Appl Biomater 2013; 102:1-11. [DOI: 10.1002/jbmb.32946] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Revised: 02/20/2013] [Accepted: 03/06/2013] [Indexed: 11/09/2022]
Affiliation(s)
- Taylor Ware
- The University of Texas at Dallas; Department of Materials Science and Engineering; Richardson Texas
| | - Dustin Simon
- The University of Texas at Dallas; Department of Materials Science and Engineering; Richardson Texas
| | - Clive Liu
- The University of Texas at Dallas; Department of Mechanical Engineering; Richardson Texas
| | | | - Srikanth Vasudevan
- The University of Texas at Arlington; Department of Bioengineering; Arlington Texas
| | - Andrew Sloan
- The University of Texas at Dallas, School of Behavioral and Brain Sciences; Richardson Texas
| | | | - Robert L. Rennaker
- The University of Texas at Dallas, School of Behavioral and Brain Sciences; Richardson Texas
| | - Walter Voit
- The University of Texas at Dallas; Department of Materials Science and Engineering; Richardson Texas
- The University of Texas at Dallas; Department of Mechanical Engineering; Richardson Texas
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Achyuta AKH, Conway AJ, Crouse RB, Bannister EC, Lee RN, Katnik CP, Behensky AA, Cuevas J, Sundaram SS. A modular approach to create a neurovascular unit-on-a-chip. LAB ON A CHIP 2013; 13:542-53. [PMID: 23108480 DOI: 10.1039/c2lc41033h] [Citation(s) in RCA: 140] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
In this work, we describe the fabrication and working of a modular microsystem that recapitulates the functions of the "Neurovascular Unit". The microdevice comprised a vertical stack of a poly(dimethylsiloxane) (PDMS) neural parenchymal chamber separated by a vascular channel via a microporous polycarbonate (PC) membrane. The neural chamber housed a mixture of neurons (~4%), astrocytes (~95%), and microglia (~1%). The vascular channel was lined with a layer of rat brain microvascular endothelial cell line (RBE4). Cellular components in the neural chamber and vascular channel showed viability (>90%). The neural cells fired inhibitory as well as excitatory potentials following 10 days of culture. The endothelial cells showed diluted-acetylated low density lipoprotein (dil-a-LDL) uptake, expressed von Willebrand factor (vWF) and zonula occludens (ZO-1) tight junctions, and showed decreased Alexafluor™-conjugated dextran leakage across their barriers significantly compared with controls (p < 0.05). When the vascular layer was stimulated with TNF-α for 6 h, about 75% of resident microglia and astrocytes on the neural side were activated significantly (p < 0.05 compared to controls) recapitulating tissue-mimetic responses resembling neuroinflammation. The impact of this microsystem lies in the fact that this biomimetic neurovascular platform might not only be harnessed for obtaining mechanistic insights for neurodegenerative disorders, but could also serve as a potential screening tool for central nervous system (CNS) therapeutics in toxicology and neuroinfectious diseases.
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Affiliation(s)
- Anil Kumar H Achyuta
- The Charles Stark Draper Laboratory, Bioengineering Center, 3802 Spectrum Blvd. Suite 201, Tampa, FL, USA.
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16
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Ereifej ES, Matthew HW, Newaz G, Mukhopadhyay A, Auner G, Salakhutdinov I, VandeVord PJ. Nanopatterning effects on astrocyte reactivity. J Biomed Mater Res A 2012. [PMID: 23184878 DOI: 10.1002/jbm.a.34480] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
An array of design strategies have been targeted toward minimizing failure of implanted microelectrodes by minimizing the chronic glial scar around the microelectrode under chronic conditions. Current approaches toward inhibiting the initiation of glial scarring range from altering the geometry, roughness, size, shape, and materials of the device. Studies have shown materials which mimic the nanotopography of the natural environment in vivo will consequently result in an improved biocompatible response. Nanofabrication of electrode arrays is being pursued in the field of neuronal electrophysiology to increase sampling capabilities. Literature shows a gap in research of nanotopography influence in the reduction of astrogliosis. The aim of this study was to determine optimal feature sizes for neural electrode fabrication, which was defined as eliciting a nonreactive astrocytic response. Nanopatterned surfaces were fabricated with nanoimprint lithography on poly(methyl methacrylate) surfaces. The rate of protein adsorption, quantity of protein adsorption, cell alignment, morphology, adhesion, proliferation, viability, and gene expression was compared between nanopatterned surfaces of different dimensions and non-nanopatterned control surfaces. Results of this study revealed that 3600 nanopatterned surfaces elicited less of a response when compared with the other patterned and non-nanopatterned surfaces. The surface instigated cell alignment along the nanopattern, less protein adsorption, less cell adhesion, proliferation and viability, inhibition of glial fibrillary acidic protein, and mitogen-activated protein kinase kinase 1 compared with all other substrates tested.
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Affiliation(s)
- Evon S Ereifej
- Department of Biomedical Engineering, Wayne State University, Detroit, Michigan, USA
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17
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Polikov VS, Hong JS, Reichert WM. Soluble factor effects on glial cell reactivity at the surface of gel-coated microwires. J Neurosci Methods 2010; 190:180-7. [PMID: 20470825 DOI: 10.1016/j.jneumeth.2010.05.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Revised: 04/28/2010] [Accepted: 05/03/2010] [Indexed: 11/29/2022]
Abstract
A basal lamina gel preparation was incorporated into a modified neuroinflammation cell culture model to test the system as a characterization tool for surface-modified microwires. The extent of gliosis at the surface of gel-coated microwires was quantified in response to titrating the cell culture with a number of soluble factors reported to be involved in reactive gliosis. Positive control conditions (1% FBS, 10 ng/ml bFGF, Neural Basal medium with B27 supplement) induced a layer of GFAP-expressing astrocytes to accumulate on all gel-coated microwires. Serum, inflammatory cytokines IL-1alpha and IL-1beta and the neural progenitor cell (NPC) proliferating growth factors bFGF and PDGF all increased the number of reactive cells on the gel, in agreement with their reported roles in cell activation, migration and proliferation at the site of injury. Technically, this study shows that a fetal neuron-glia culture system is well suited for characterizing the impact of electrode coatings designed to mitigate implant-associated gliosis, and for screening the effect of multiple soluble factors that promote and/or inhibit implant-associated gliosis. Scientifically, this study points to essential roles of serum and inflammatory factors to induce NPC activation and migration to the site of injury, where growth factors like bFGF and PDGF induce proliferation of cells that will eventually form the glial scar.
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