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Abstract
Cochlear implants (CI) restore functional hearing in the majority of deaf patients. Despite the tremendous success of these devices, some limitations remain. The bottleneck for optimal electrical stimulation with CI is caused by the anatomical gap between the electrode array and the auditory neurons in the inner ear. As a consequence, current devices are limited through 1) low frequency resolution, hence sub-optimal sound quality and 2), large stimulation currents, hence high energy consumption (responsible for significant battery costs and for impeding the development of fully implantable systems). A recently completed, multinational and interdisciplinary project called NANOCI aimed at overcoming current limitations by creating a gapless interface between auditory nerve fibers and the cochlear implant electrode array. This ambitious goal was achieved in vivo by neurotrophin-induced attraction of neurites through an intracochlear gel-nanomatrix onto a modified nanoCI electrode array located in the scala tympani of deafened guinea pigs. Functionally, the gapless interface led to lower stimulation thresholds and a larger dynamic range in vivo, and to reduced stimulation energy requirement (up to fivefold) in an in vitro model using auditory neurons cultured on multi-electrode arrays. In conclusion, the NANOCI project yielded proof of concept that a gapless interface between auditory neurons and cochlear implant electrode arrays is feasible. These findings may be of relevance for the development of future CI systems with better sound quality and performance and lower energy consumption. The present overview/review paper summarizes the NANOCI project history and highlights achievements of the individual work packages.
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Yan W, Liu W, Qi J, Fang Q, Fan Z, Sun G, Han Y, Zhang D, Xu L, Wang M, Li J, Chen F, Liu D, Chai R, Wang H. A Three-Dimensional Culture System with Matrigel Promotes Purified Spiral Ganglion Neuron Survival and Function In Vitro. Mol Neurobiol 2017; 55:2070-2084. [PMID: 28283883 DOI: 10.1007/s12035-017-0471-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 02/23/2017] [Indexed: 12/01/2022]
Abstract
In vitro culture of spiral ganglion neurons (SGNs) is a useful approach to investigate numerous aspects of neuronal behavior and to identify potential therapeutic targets for SGN protection and regeneration. However, the isolation of SGNs and the long-term maintenance of their structure and function in vitro remain challenging. In this study, we isolated SGNs from Bhlhb5-cre and Rosa26-tdTomato mice with fluorescence-activated cell sorting and determined the cell purity. We then encapsulated the pure SGNs in matrigel and cultured the SGNs in vitro. We found that the three-dimensional (3D)-matrigel culture environment significantly suppressed apoptosis and improved SGN survival in vitro, which enabled the long-term culture of SGNs for up to 6 months. The 3D-matrigel system also significantly promoted neurite outgrowth of the SGNs, increased the cells' polarity, promoted the area of growth cones, and significantly increased the synapse density of the SGNs. More importantly, the 3D-matrigel system helped to maintain and promote the electrophysiological properties of the SGNs. In conclusion, the 3D-matrigel culture system promoted the survival of purified SGNs in vitro and maintained their morphological structure and function and thus could be a useful tool for studying the physiology and pathophysiology of purified SGNs in long-term culture.
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Affiliation(s)
- Wenqing Yan
- Otolaryngology-Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, China.,Shandong Provincial Key Laboratory of Otology, Jinan, China
| | - Wenwen Liu
- Otolaryngology-Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, China.,Shandong Provincial Key Laboratory of Otology, Jinan, China
| | - Jieyu Qi
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China.,Co-innovation Center of Neuroregeneration, Jiangsu Key Laboratory of Neuroregeneration, Nantong University, Qixiu Road 19, Nantong, 226001, China.,Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, Southeast University, Nanjing, 210096, China
| | - Qiaojun Fang
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China.,Co-innovation Center of Neuroregeneration, Jiangsu Key Laboratory of Neuroregeneration, Nantong University, Qixiu Road 19, Nantong, 226001, China.,Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, Southeast University, Nanjing, 210096, China
| | - Zhaomin Fan
- Otolaryngology-Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, China.,Shandong Provincial Key Laboratory of Otology, Jinan, China
| | - Gaoying Sun
- Otolaryngology-Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, China.,Shandong Provincial Key Laboratory of Otology, Jinan, China
| | - Yuechen Han
- Otolaryngology-Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, China.,Shandong Provincial Key Laboratory of Otology, Jinan, China
| | - Daogong Zhang
- Otolaryngology-Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, China.,Shandong Provincial Key Laboratory of Otology, Jinan, China
| | - Lei Xu
- Otolaryngology-Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, China.,Shandong Provincial Key Laboratory of Otology, Jinan, China
| | - Mingming Wang
- Otolaryngology-Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, China.,Shandong Provincial Key Laboratory of Otology, Jinan, China
| | - Jianfeng Li
- Otolaryngology-Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, China.,Shandong Provincial Key Laboratory of Otology, Jinan, China
| | - Fangyi Chen
- Department of Biology, South University of Science and Technology of China, Shenzhen, China
| | - Dong Liu
- Co-innovation Center of Neuroregeneration, Jiangsu Key Laboratory of Neuroregeneration, Nantong University, Qixiu Road 19, Nantong, 226001, China.
| | - Renjie Chai
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China. .,Co-innovation Center of Neuroregeneration, Jiangsu Key Laboratory of Neuroregeneration, Nantong University, Qixiu Road 19, Nantong, 226001, China. .,Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, Southeast University, Nanjing, 210096, China.
| | - Haibo Wang
- Otolaryngology-Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, China. .,Shandong Provincial Key Laboratory of Otology, Jinan, China.
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Li H, Edin F, Hayashi H, Gudjonsson O, Danckwardt-Lillieström N, Engqvist H, Rask-Andersen H, Xia W. Guided growth of auditory neurons: Bioactive particles towards gapless neural - electrode interface. Biomaterials 2016; 122:1-9. [PMID: 28107660 DOI: 10.1016/j.biomaterials.2016.12.020] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 11/30/2016] [Accepted: 12/16/2016] [Indexed: 01/26/2023]
Abstract
Cochlear implant (CI) is a successful device to restore hearing. Despite continuous development, frequency discrimination is poor in CI users due to an anatomical gap between the auditory neurons and CI electrode causing current spread and unspecific neural stimulation. One strategy to close this anatomical gap is guiding the growth of neuron dendrites closer to CI electrodes through targeted slow release of neurotrophins. Biodegradable calcium phosphate hollow nanospheres (CPHSs) were produced and their capacity for uptake and release of neurotrophins investigated using 125I-conjugated glia cell line-derived neurotrophic factor (GDNF). The CPHSs were coated onto CI electrodes and loaded with neurotrophins. Axon guidance effect of slow-released neurotrophins from the CPHSs was studied in an in vitro 3D culture model. CPHS coating bound and released GDNF with an association rate constant 6.3 × 103 M-1s-1 and dissociation rate 2.6 × 10-5 s-1, respectively. Neurites from human vestibulocochlear ganglion explants found and established physical contact with the GDNF-loaded CPHS coating on the CI electrodes placed 0.7 mm away. Our results suggest that neurotrophin delivery through CPHS coating is a plausible way to close the anatomical gap between auditory neurons and electrodes. By overcoming this gap, selective neural activation and the fine hearing for CI users become possible.
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Affiliation(s)
- Hao Li
- Otolaryngology and Head & Neck Surgery, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Fredrik Edin
- Otolaryngology and Head & Neck Surgery, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | | | - Olafur Gudjonsson
- Neurosurgery, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | | | - Håkan Engqvist
- Applied Material Science, Department of Engineering Sciences, Uppsala University, Uppsala, Sweden
| | - Helge Rask-Andersen
- Otolaryngology and Head & Neck Surgery, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden.
| | - Wei Xia
- Applied Material Science, Department of Engineering Sciences, Uppsala University, Uppsala, Sweden.
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Di Sante G, Casimiro MC, Pestell TG, Pestell RG. Time-Lapse Video Microscopy for Assessment of EYFP-Parkin Aggregation as a Marker for Cellular Mitophagy. J Vis Exp 2016. [PMID: 27168174 DOI: 10.3791/53657] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Time-lapse video microscopy can be defined as the real time imaging of living cells. This technique relies on the collection of images at different time points. Time intervals can be set through a computer interface that controls the microscope-integrated camera. This kind of microscopy requires both the ability to acquire very rapid events and the signal generated by the observed cellular structure during these events. After the images have been collected, a movie of the entire experiment is assembled to show the dynamic of the molecular events of interest. Time-lapse video microscopy has a broad range of applications in the biomedical research field and is a powerful and unique tool for following the dynamics of the cellular events in real time. Through this technique, we can assess cellular events such as migration, division, signal transduction, growth, and death. Moreover, using fluorescent molecular probes we are able to mark specific molecules, such as DNA, RNA or proteins and follow them through their molecular pathways and functions. Time-lapse video microscopy has multiple advantages, the major one being the ability to collect data at the single-cell level, that make it a unique technology for investigation in the field of cell biology. However, time-lapse video microscopy has limitations that can interfere with the acquisition of high quality images. Images can be compromised by both external factors; temperature fluctuations, vibrations, humidity and internal factors; pH, cell motility. Herein, we describe a protocol for the dynamic acquisition of a specific protein, Parkin, fused with the enhanced yellow fluorescent protein (EYFP) in order to track the selective removal of damaged mitochondria, using a time-lapse video microscopy approach.
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Affiliation(s)
| | | | | | - Richard G Pestell
- Department of Cancer Biology, Thomas Jefferson University, SKCC; Department of Medical Oncology, Thomas Jefferson University, SKCC; Kazan Federal University;
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Cai Y, Edin F, Jin Z, Alexsson A, Gudjonsson O, Liu W, Rask-Andersen H, Karlsson M, Li H. Strategy towards independent electrical stimulation from cochlear implants: Guided auditory neuron growth on topographically modified nanocrystalline diamond. Acta Biomater 2016; 31:211-220. [PMID: 26593784 DOI: 10.1016/j.actbio.2015.11.021] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 11/10/2015] [Accepted: 11/14/2015] [Indexed: 12/14/2022]
Abstract
Cochlear implants (CI) have been used for several decades to treat patients with profound hearing loss. Nevertheless, results vary between individuals, and fine hearing is generally poor due to the lack of discrete neural stimulation from the individual receptor hair cells. A major problem is the deliverance of independent stimulation signals to individual auditory neurons. Fine hearing requires significantly more stimulation contacts with intimate neuron/electrode interphases from ordered axonal re-growth, something current CI technology cannot provide. Here, we demonstrate the potential application of micro-textured nanocrystalline diamond (NCD) surfaces on CI electrode arrays. Such textured NCD surfaces consist of micrometer-sized nail-head-shaped pillars (size 5×5μm(2)) made with sequences of micro/nano-fabrication processes, including sputtering, photolithography and plasma etching. The results show that human and murine inner-ear ganglion neurites and, potentially, neural progenitor cells can attach to patterned NCD surfaces without an extracellular matrix coating. Microscopic methods revealed adhesion and neural growth, specifically along the nail-head-shaped NCD pillars in an ordered manner, rather than in non-textured areas. This pattern was established when the inter-NCD pillar distance varied between 4 and 9μm. The findings demonstrate that regenerating auditory neurons show a strong affinity to the NCD pillars, and the technique could be used for neural guidance and the creation of new neural networks. Together with the NCD's unique anti-bacterial and electrical properties, patterned NCD surfaces could provide designed neural/electrode interfaces to create independent electrical stimulation signals in CI electrode arrays for the neural population. STATEMENT OF SIGNIFICANCE Cochlear implant is currently a successful way to treat sensorineural hearing loss and deafness especially in children. Although clinically successful, patients' fine hearing cannot be completely restored. One problem is the amount of the electrodes; 12-20 electrodes are used to replace the function of 3400 inner hair cells. Intense research is ongoing aiming to increase the number of electrodes. This study demonstrates the use of nanocrystalline diamond as a potential nerve-electrode interface. Micrometer-sized nanocrystalline diamond pillars showed high affinity to regenerated human neurons, which grew into a pre-defined network based on the pillar design. Our findings are of particular interest since they can be applied on any silicon-based implant to increase electrode count and to achieve individual neuron stimulation patterns.
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Affiliation(s)
- Yixiao Cai
- Department of Engineering Sciences, Ångström Laboratory, Uppsala University, Uppsala, Sweden
| | - Fredrik Edin
- Otolaryngology and Head & Neck Surgery, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Zhe Jin
- Physiology; Molecular Physiology and Neuroscience, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Andrei Alexsson
- Rheumatology, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - Olafur Gudjonsson
- Neurosurgery, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Wei Liu
- Otolaryngology and Head & Neck Surgery, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Helge Rask-Andersen
- Otolaryngology and Head & Neck Surgery, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Mikael Karlsson
- Department of Engineering Sciences, Ångström Laboratory, Uppsala University, Uppsala, Sweden.
| | - Hao Li
- Otolaryngology and Head & Neck Surgery, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden.
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The Three-Dimensional Culture System with Matrigel and Neurotrophic Factors Preserves the Structure and Function of Spiral Ganglion Neuron In Vitro. Neural Plast 2016; 2016:4280407. [PMID: 27057364 PMCID: PMC4736769 DOI: 10.1155/2016/4280407] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 11/10/2015] [Indexed: 02/06/2023] Open
Abstract
Whole organ culture of the spiral ganglion region is a resourceful model system facilitating manipulation and analysis of live sprial ganglion neurons (SGNs). Three-dimensional (3D) cultures have been demonstrated to have many biomedical applications, but the effect of 3D culture in maintaining the SGNs structure and function in explant culture remains uninvestigated. In this study, we used the matrigel to encapsulate the spiral ganglion region isolated from neonatal mice. First, we optimized the matrigel concentration for the 3D culture system and found the 3D culture system protected the SGNs against apoptosis, preserved the structure of spiral ganglion region, and promoted the sprouting and outgrowth of SGNs neurites. Next, we found the 3D culture system promoted growth cone growth as evidenced by a higher average number and a longer average length of filopodia and a larger growth cone area. 3D culture system also significantly elevated the synapse density of SGNs. Last, we found that the 3D culture system combined with neurotrophic factors had accumulated effects in promoting the neurites outgrowth compared with 3D culture or NFs treatment only groups. Together, we conclude that the 3D culture system preserves the structure and function of SGN in explant culture.
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