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Hemachandran S, Hu N, Kane CJ, Green SH. Cyclic AMP signaling promotes regeneration of cochlear synapses after excitotoxic or noise trauma. Front Cell Neurosci 2024; 18:1363219. [PMID: 38694536 PMCID: PMC11061447 DOI: 10.3389/fncel.2024.1363219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Accepted: 03/27/2024] [Indexed: 05/04/2024] Open
Abstract
Introduction Cochlear afferent synapses connecting inner hair cells to spiral ganglion neurons are susceptible to excitotoxic trauma on exposure to loud sound, resulting in a noise-induced cochlear synaptopathy (NICS). Here we assessed the ability of cyclic AMP-dependent protein kinase (PKA) signaling to promote cochlear synapse regeneration, inferred from its ability to promote axon regeneration in axotomized CNS neurons, another system refractory to regeneration. Methods We mimicked NICS in vitro by applying a glutamate receptor agonist, kainic acid (KA) to organotypic cochlear explant cultures and experimentally manipulated cAMP signaling to determine whether PKA could promote synapse regeneration. We then delivered the cAMP phosphodiesterase inhibitor rolipram via implanted subcutaneous minipumps in noise-exposed CBA/CaJ mice to test the hypothesis that cAMP signaling could promote cochlear synapse regeneration in vivo. Results We showed that the application of the cell membrane-permeable cAMP agonist 8-cpt-cAMP or the cAMP phosphodiesterase inhibitor rolipram promotes significant regeneration of synapses in vitro within twelve hours after their destruction by KA. This is independent of neurotrophin-3, which also promotes synapse regeneration. Moreover, of the two independent signaling effectors activated by cAMP - the cAMP Exchange Protein Activated by cAMP and the cAMP-dependent protein kinase - it is the latter that mediates synapse regeneration. Finally, we showed that systemic delivery of rolipram promotes synapse regeneration in vivo following NICS. Discussion In vitro experiments show that cAMP signaling promotes synapse regeneration after excitotoxic destruction of cochlear synapses and does so via PKA signaling. The cAMP phosphodiesterase inhibitor rolipram promotes synapse regeneration in vivo in noise-exposed mice. Systemic administration of rolipram or similar compounds appears to provide a minimally invasive therapeutic approach to reversing synaptopathy post-noise.
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Affiliation(s)
| | | | | | - Steven H. Green
- Department of Biology, University of Iowa, Iowa City, IA, United States
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2
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Vecchi JT, Rhomberg M, Guymon CA, Hansen MR. The geometry of photopolymerized topography influences neurite pathfinding by directing growth cone morphology and migration. J Neural Eng 2024; 21:026027. [PMID: 38547528 PMCID: PMC10993768 DOI: 10.1088/1741-2552/ad38dc] [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: 09/20/2023] [Revised: 03/15/2024] [Accepted: 03/28/2024] [Indexed: 04/05/2024]
Abstract
Objective. Cochlear implants provide auditory perception to those with severe to profound sensorineural hearing loss: however, the quality of sound perceived by users does not approximate natural hearing. This limitation is due in part to the large physical gap between the stimulating electrodes and their target neurons. Therefore, directing the controlled outgrowth of processes from spiral ganglion neurons (SGNs) into close proximity to the electrode array could provide significantly increased hearing function.Approach.For this objective to be properly designed and implemented, the ability and limits of SGN neurites to be guided must first be determined. In this work, we engineer precise topographical microfeatures with angle turn challenges of various geometries to study SGN pathfinding and use live imaging to better understand how neurite growth is guided by these cues.Main Results.We find that the geometry of the angled microfeatures determines the ability of neurites to navigate the angled microfeature turns. SGN neurite pathfinding fidelity is increased by 20%-70% through minor increases in microfeature amplitude (depth) and by 25% if the angle of the patterned turn is made obtuse. Further, we see that dorsal root ganglion neuron growth cones change their morphology and migration to become more elongated within microfeatures. Our observations also indicate complexities in studying neurite turning. First, as the growth cone pathfinds in response to the various cues, the associated neurite often reorients across the angle topographical microfeatures. Additionally, neurite branching is observed in response to topographical guidance cues, most frequently when turning decisions are most uncertain.Significance.Overall, the multi-angle channel micropatterned substrate is a versatile and efficient system to assess neurite turning and pathfinding in response to topographical cues. These findings represent fundamental principles of neurite pathfinding that will be essential to consider for the design of 3D systems aiming to guide neurite growthin vivo.
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Affiliation(s)
- Joseph T Vecchi
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA, United States of America
- Department of Otolaryngology Head-Neck Surgery, University of Iowa, Iowa City, IA, United States of America
| | - Madeline Rhomberg
- Department of Otolaryngology Head-Neck Surgery, University of Iowa, Iowa City, IA, United States of America
| | - C Allan Guymon
- Department of Chemical and Biochemical Engineering, University of Iowa, Iowa City, IA, United States of America
| | - Marlan R Hansen
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA, United States of America
- Department of Otolaryngology Head-Neck Surgery, University of Iowa, Iowa City, IA, United States of America
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3
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Vecchi JT, Rhomberg M, Guymon CA, Hansen MR. The geometry of photopolymerized topography influences neurite pathfinding by directing growth cone morphology and migration. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.28.555111. [PMID: 37693432 PMCID: PMC10491164 DOI: 10.1101/2023.08.28.555111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Cochlear implants (CIs) provide auditory perception to those with profound sensorineural hearing loss: however, the quality of sound perceived by a CI user does not approximate natural hearing. This limitation is due in part to the large physical gap between the stimulating electrodes and their target neurons. Therefore, directing the controlled outgrowth of processes from spiral ganglion neurons (SGNs) into close proximity to the electrode array could provide significantly increased hearing function. For this objective to be properly designed and implemented, the ability and limits of SGN neurites to be guided must first be determined. In this work, we engineered precise topographical microfeatures with angle turn challenges of various geometries to study SGN pathfinding. Additionally, we analyze sensory neurite growth in response to topographically patterned substrates and use live imaging to better understand how neurite growth is guided by these cues. In assessing the ability of neurites to sense and turn in response to topographical cues, we find that the geometry of the angled microfeatures determines the ability of neurites to navigate the angled microfeature turns. SGN neurite pathfinding fidelity can be increased by 20-70% through minor increases in microfeature amplitude (depth) and by 25% if the angle of the patterned turn is made more obtuse. Further, by using engineered topographies and live imaging of dorsal root ganglion neurons (DRGNs), we see that DRGN growth cones change their morphology and migration to become more elongated within microfeatures. However, our observations also indicate complexities in studying neurite turning. First, as the growth cone pathfinds in response to the various cues, the associated neurite often reorients across the angle topographical microfeatures. This reorientation is likely related to the tension the neurite shaft experiences when the growth cone elongates in the microfeature around a turn. Additionally, neurite branching is observed in response to topographical guidance cues, most frequently when turning decisions are most uncertain. Overall, the multi-angle channel micropatterned substrate is a versatile and efficient system to assess SGN neurite turning and pathfinding in response to topographical cues. These findings represent fundamental principles of neurite pathfinding that will be essential to consider for the design of 3D systems aiming to guide neurite growth in vivo.
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Affiliation(s)
- Joseph T. Vecchi
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, Iowa City, IA, USA
- Department of Otolaryngology Head-Neck Surgery, Carver College of Medicine, Iowa City, IA, USA
| | - Madeline Rhomberg
- Department of Otolaryngology Head-Neck Surgery, Carver College of Medicine, 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 Molecular Physiology and Biophysics, Carver College of Medicine, Iowa City, IA, USA
- Department of Otolaryngology Head-Neck Surgery, Carver College of Medicine, Iowa City, IA, USA
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4
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Pisani A, Paciello F, Del Vecchio V, Malesci R, De Corso E, Cantone E, Fetoni AR. The Role of BDNF as a Biomarker in Cognitive and Sensory Neurodegeneration. J Pers Med 2023; 13:jpm13040652. [PMID: 37109038 PMCID: PMC10140880 DOI: 10.3390/jpm13040652] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 04/04/2023] [Accepted: 04/08/2023] [Indexed: 04/29/2023] Open
Abstract
Brain-derived neurotrophic factor (BDNF) has a crucial function in the central nervous system and in sensory structures including olfactory and auditory systems. Many studies have highlighted the protective effects of BDNF in the brain, showing how it can promote neuronal growth and survival and modulate synaptic plasticity. On the other hand, conflicting data about BDNF expression and functions in the cochlear and in olfactory structures have been reported. Several clinical and experimental research studies showed alterations in BDNF levels in neurodegenerative diseases affecting the central and peripheral nervous system, suggesting that BDNF can be a promising biomarker in most neurodegenerative conditions, including Alzheimer's disease, shearing loss, or olfactory impairment. Here, we summarize current research concerning BDNF functions in brain and in sensory domains (olfaction and hearing), focusing on the effects of the BDNF/TrkB signalling pathway activation in both physiological and pathological conditions. Finally, we review significant studies highlighting the possibility to target BDNF as a biomarker in early diagnosis of sensory and cognitive neurodegeneration, opening new opportunities to develop effective therapeutic strategies aimed to counteract neurodegeneration.
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Affiliation(s)
- Anna Pisani
- Department of Otolaryngology Head and Neck Surgery, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
| | - Fabiola Paciello
- Department of Neuroscience, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
- Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy
| | - Valeria Del Vecchio
- Department of Neuroscience, Reproductive Sciences and Dentistry-Audiology Section, University of Naples Federico II, 80131 Naples, Italy
| | - Rita Malesci
- Department of Neuroscience, Reproductive Sciences and Dentistry-Audiology Section, University of Naples Federico II, 80131 Naples, Italy
| | - Eugenio De Corso
- Department of Otolaryngology Head and Neck Surgery, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
- Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy
| | - Elena Cantone
- Department of Neuroscience, Reproductive Sciences and Dentistry-ENT Section, University of Naples Federico II, 80131 Naples, Italy
| | - Anna Rita Fetoni
- Department of Neuroscience, Reproductive Sciences and Dentistry-Audiology Section, University of Naples Federico II, 80131 Naples, Italy
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Li Y, Hu Y, Wei H, Cao W, Qi Y, Zhou S, Zhang P, Li H, Li GL, Chai R. Two-dimensional Ti 3C 2T x MXene promotes electrophysiological maturation of neural circuits. J Nanobiotechnology 2022; 20:398. [PMID: 36045382 PMCID: PMC9434915 DOI: 10.1186/s12951-022-01590-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 08/09/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The ideal neural interface or scaffold for stem cell therapy shall have good biocompatibility promoting survival, maturation and integration of neural stem cells (NSCs) in targeted brain regions. The unique electrical, hydrophilic and surface-modifiable properties of Ti3C2Tx MXene make it an attractive substrate, but little is known about how it interacts with NSCs during development and maturation. RESULTS In this study, we cultured NSCs on Ti3C2Tx MXene and examined its effects on morphological and electrophysiological properties of NSC-derived neurons. With a combination of immunostaining and patch-clamp recording, we found that Ti3C2Tx MXene promotes NSCs differentiation and neurite growth, increases voltage-gated current of Ca2+ but not Na+ or K+ in matured neurons, boosts their spiking without changing their passive membrane properties, and enhances synaptic transmission between them. CONCLUSIONS These results expand our understanding of interaction between Ti3C2Tx MXene and NSCs and provide a critical line of evidence for using Ti3C2Tx MXene in neural interface or scaffold in stem cell therapy.
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Affiliation(s)
- Yige Li
- State Key Laboratory of Bioelectronics, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China
| | - Yangnan Hu
- State Key Laboratory of Bioelectronics, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China
| | - Hao Wei
- Department of Otolaryngology Head and Neck Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, 210008, China
| | - Wei Cao
- Department of Otorhinolaryngology, Head and Neck Surgery, The Second Hospital of Anhui Medical University, Hefei, 230069, China
| | - Yanru Qi
- State Key Laboratory of Bioelectronics, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China
| | - Shan Zhou
- State Key Laboratory of Bioelectronics, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China
| | - Panpan Zhang
- State Key Laboratory of Bioelectronics, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China
| | - Huawei Li
- Department of Otorhinolaryngology and ENT Institute, Eye and ENT Hospital, Fudan University, Shanghai, 200031, China. .,State Key Laboratory of Medical Neurobiology, and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China. .,Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China. .,NHC Key Laboratory of Hearing Medicine Fudan University, Shanghai, 200031, China. .,Institutes of Brain Science and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200032, China.
| | - Geng-Lin Li
- Department of Otorhinolaryngology and ENT Institute, Eye and ENT Hospital, Fudan University, Shanghai, 200031, China. .,State Key Laboratory of Medical Neurobiology, and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China. .,NHC Key Laboratory of Hearing Medicine Fudan University, Shanghai, 200031, China.
| | - Renjie Chai
- State Key Laboratory of Bioelectronics, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China. .,Department of Otolaryngology Head and Neck Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, 210008, China. .,Department of Otolaryngology Head and Neck Surgery, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, China. .,Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China. .,Institute for Stem Cell and Regeneration, Chinese Academy of Science, Beijing, 100086, China. .,Beijing Key Laboratory of Neural Regeneration and Repair, Capital Medical University, Beijing, 100069, China.
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6
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St. Peter M, Brough DE, Lawrence A, Nelson-Brantley J, Huang P, Harre J, Warnecke A, Staecker H. Improving Control of Gene Therapy-Based Neurotrophin Delivery for Inner Ear Applications. Front Bioeng Biotechnol 2022; 10:892969. [PMID: 35721868 PMCID: PMC9204055 DOI: 10.3389/fbioe.2022.892969] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 04/27/2022] [Indexed: 11/13/2022] Open
Abstract
Background: Survival and integrity of the spiral ganglion is vital for hearing in background noise and for optimal functioning of cochlear implants. Numerous studies have demonstrated that supplementation of supraphysiologic levels of the neurotrophins BDNF and NT-3 by pumps or gene therapy strategies supports spiral ganglion survival. The endogenous physiological levels of growth factors within the inner ear, although difficult to determine, are likely extremely low within the normal inner ear. Thus, novel approaches for the long-term low-level delivery of neurotrophins may be advantageous. Objectives: This study aimed to evaluate the long-term effects of gene therapy-based low-level neurotrophin supplementation on spiral ganglion survival. Using an adenovirus serotype 28-derived adenovector delivery system, the herpes latency promoter, a weak, long expressing promoter system, has been used to deliver the BDNF or NTF3 genes to the inner ear after neomycin-induced ototoxic injury in mice. Results: Treatment of the adult mouse inner ear with neomycin resulted in acute and chronic changes in endogenous neurotrophic factor gene expression and led to a degeneration of spiral ganglion cells. Increased survival of spiral ganglion cells after adenoviral delivery of BDNF or NTF3 to the inner ear was observed. Expression of BDNF and NT-3 could be demonstrated in the damaged organ of Corti after gene delivery. Hearing loss due to overexpression of neurotrophins in the normal hearing ear was avoided when using this novel vector–promoter combination. Conclusion: Combining supporting cell-specific gene delivery via the adenovirus serotype 28 vector with a low-strength long expressing promoter potentially can provide long-term neurotrophin delivery to the damaged inner ear.
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Affiliation(s)
| | | | - Anna Lawrence
- Department of Otolaryngology, University of Kansas School of Medicine, Kansas City, KS, United States
| | | | - Peixin Huang
- Department of Otolaryngology, University of Kansas School of Medicine, Kansas City, KS, United States
| | - Jennifer Harre
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Athanasia Warnecke
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Hinrich Staecker
- Department of Otolaryngology, University of Kansas School of Medicine, Kansas City, KS, United States
- *Correspondence: Hinrich Staecker,
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Crozier RA, Wismer ZQ, Parra-Munevar J, Plummer MR, Davis RL. Amplification of input differences by dynamic heterogeneity in the spiral ganglion. J Neurophysiol 2022; 127:1317-1333. [PMID: 35389760 PMCID: PMC9054264 DOI: 10.1152/jn.00544.2021] [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: 12/20/2021] [Revised: 03/30/2022] [Accepted: 03/30/2022] [Indexed: 11/22/2022] Open
Abstract
A defining feature of type I primary auditory afferents that compose ∼95% of the spiral ganglion is their intrinsic electrophysiological heterogeneity. This diversity is evident both between and within unitary, rapid, and slow adaptation (UA, RA, and SA) classes indicative of specializations designed to shape sensory receptor input. But to what end? Our initial impulse is to expect the opposite: that auditory afferents fire uniformly to represent acoustic stimuli with accuracy and high fidelity. Yet this is clearly not the case. One explanation for this neural signaling strategy is to coordinate a system in which differences between input stimuli are amplified. If this is correct, then stimulus disparity enhancements within the primary afferents should be transmitted seamlessly into auditory processing pathways that utilize population coding for difference detection. Using sound localization as an example, one would expect to observe separately regulated differences in intensity level compared with timing or spectral cues within a graded tonotopic distribution. This possibility was evaluated by examining the neuromodulatory effects of cAMP on immature neurons with high excitability and slow membrane kinetics. We found that electrophysiological correlates of intensity and timing were indeed independently regulated and tonotopically distributed, depending on intracellular cAMP signaling level. These observations, therefore, are indicative of a system in which differences between signaling elements of individual stimulus attributes are systematically amplified according to auditory processing constraints. Thus, dynamic heterogeneity mediated by cAMP in the spiral ganglion has the potential to enhance the representations of stimulus input disparities transmitted into higher level difference detection circuitry.NEW & NOTEWORTHY Can changes in intracellular second messenger signaling within primary auditory afferents shift our perception of sound? Results presented herein lead to this conclusion. We found that intracellular cAMP signaling level systematically altered the kinetics and excitability of primary auditory afferents, exemplifying how dynamic heterogeneity can enhance differences between electrophysiological correlates of timing and intensity.
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Affiliation(s)
| | - Zachary Q Wismer
- AtlantiCare Regional Medical Center, Department of Family Medicine, Atlantic City, New Jersey
| | - Jeffrey Parra-Munevar
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey
| | - Mark R Plummer
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey
| | - Robin L Davis
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey
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Rousset F, Schmidbauer D, Fink S, Adel Y, Obexer B, Müller M, Glueckert R, Löwenheim H, Senn P. Phoenix auditory neurons as 3R cell model for high throughput screening of neurogenic compounds. Hear Res 2021; 414:108391. [PMID: 34844170 DOI: 10.1016/j.heares.2021.108391] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 10/25/2021] [Accepted: 10/27/2021] [Indexed: 11/25/2022]
Abstract
Auditory neurons connect the sensory hair cells from the inner ear to the brainstem. These bipolar neurons are relevant targets for pharmacological intervention aiming at protecting or improving the hearing function in various forms of sensorineural hearing loss. In the research laboratory, neurotrophic compounds are commonly used to improve survival and to promote regeneration of auditory neurons. One important roadblock delaying eventual clinical applications of these strategies in humans is the lack of powerful in vitro models allowing high throughput screening of otoprotective and regenerative compounds. The recently discovered auditory neuroprogenitors (ANPGs) derived from the A/J mouse with an unprecedented capacity to self-renew and to provide mature auditory neurons offer the possibility to overcome this bottleneck. In the present study, we further characterized the new phoenix ANPGs model and compared it to the current gold-standard spiral ganglion organotypic explant (SGE) model to assay neurite outgrowth, neurite length and glutamate-induced Ca2+ response in response to neurotrophin-3 (NT-3) and brain derived neurotrophic factor (BDNF) treatment. Whereas both, SGEs and phoenix ANPGs exhibited a robust and sensitive response to neurotrophins, the phoenix ANPGs offer a considerable range of advantages including high throughput suitability, lower experimental variability, single cell resolution and an important reduction of animal numbers. The phoenix ANPGs in vitro model therefore provides a robust high-throughput platform to screen for otoprotective and regenerative neurotrophic compounds in line with 3R principles and is of interest for the field of auditory neuroscience.
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Affiliation(s)
- Francis Rousset
- The Inner Ear & Olfaction Lab, Department of Pathology and Immunology, Faculty of Medicine, University of Geneva, Switzerland.
| | - Dominik Schmidbauer
- Inner Ear Laboratory, Department of Otolaryngology, Medical University of Innsbruck, Austria
| | - Stefan Fink
- Translational Hearing Research, Tübingen Hearing Research Center, Department of Otolaryngology, Head & Neck Surgery, University of Tübingen, Germany
| | - Youssef Adel
- Translational Hearing Research, Tübingen Hearing Research Center, Department of Otolaryngology, Head & Neck Surgery, University of Tübingen, Germany
| | - Benjamin Obexer
- Inner Ear Laboratory, Department of Otolaryngology, Medical University of Innsbruck, Austria
| | - Marcus Müller
- Translational Hearing Research, Tübingen Hearing Research Center, Department of Otolaryngology, Head & Neck Surgery, University of Tübingen, Germany
| | - Rudolf Glueckert
- Inner Ear Laboratory, Department of Otolaryngology, Medical University of Innsbruck, Austria.
| | - Hubert Löwenheim
- Translational Hearing Research, Tübingen Hearing Research Center, Department of Otolaryngology, Head & Neck Surgery, University of Tübingen, Germany
| | - Pascal Senn
- The Inner Ear & Olfaction Lab, Department of Pathology and Immunology, Faculty of Medicine, University of Geneva, Switzerland; Department of Clinical Neurosciences, Service of ORL & Head and Neck Surgery, University Hospital of Geneva, Switzerland
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9
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Harre J, Heinkele L, Steffens M, Warnecke A, Lenarz T, Just I, Rohrbeck A. Potentiation of Brain-Derived Neurotrophic Factor-Induced Protection of Spiral Ganglion Neurons by C3 Exoenzyme/Rho Inhibitor. Front Cell Neurosci 2021; 15:602897. [PMID: 33776650 PMCID: PMC7991574 DOI: 10.3389/fncel.2021.602897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 02/19/2021] [Indexed: 11/17/2022] Open
Abstract
Preservation of the excitability of spiral ganglion neurons (SGN) may contribute to an improved speech perception after cochlear implantation. Thus, the application of exogenous neurotrophic factors such as the neurotrophin brain-derived neurotrophic factor (BDNF) to increase SGN survival in vitro and in vivo is a promising pharmacological approach in cochlear implant (CI) research. Due to the difficult pharmacokinetic profile of proteins such as BDNF, there is a quest for small molecules to mediate the survival of SGN or to increase the efficacy of BDNF. The C3 exoenzyme from Clostridium botulinum could be a potential new candidate for the protection and regeneration of SGN. Inhibition of the RhoA GTPase pathway which can be mediated by C3 is described as a promising strategy to enhance axonal regeneration and to exert pro-survival signals in neurons. Nanomolar concentrations of C3, its enzymatically inactive form C3E174Q, and a 26mer C-terminal peptide fragment covering amino acid 156–181 (C3156-181) potentiated the neuroprotective effect on SGN mediated by BDNF in vitro. The neuroprotective effect of C3/BDNF was reduced to the neuroprotective effect of BDNF alone after the treatment with wortmannin, an inhibitor of the phosphatidylinositol-3-kinase (PI3K).The exoenzyme C3 (wild-type and enzyme-deficient) and the C3 peptide fragment C3154–181 present novel biologically active compounds for the protection of the SGN. The exact underlying intracellular mechanisms that mediate the neuroprotective effect are not clarified yet, but the combination of BDNF (TrkB stimulation) and C3 exoenzyme (RhoA inhibition) can be used to protect SGN in vitro.
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Affiliation(s)
- Jennifer Harre
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Hannover, Germany.,Cluster of Excellence "Hearing4all" of the German Research Foundation (EXC 2177/1), Hannover, Germany
| | - Laura Heinkele
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Hannover, Germany
| | - Melanie Steffens
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Hannover, Germany
| | - Athanasia Warnecke
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Hannover, Germany.,Cluster of Excellence "Hearing4all" of the German Research Foundation (EXC 2177/1), Hannover, Germany
| | - Thomas Lenarz
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Hannover, Germany.,Cluster of Excellence "Hearing4all" of the German Research Foundation (EXC 2177/1), Hannover, Germany
| | - Ingo Just
- Institute of Toxicology, Hannover Medical School, Hannover, Germany
| | - Astrid Rohrbeck
- Institute of Toxicology, Hannover Medical School, Hannover, Germany
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10
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Shen N, Zhou L, Lai B, Li S. The Influence of Cochlear Implant-Based Electric Stimulation on the Electrophysiological Characteristics of Cultured Spiral Ganglion Neurons. Neural Plast 2020; 2020:3108490. [PMID: 32963515 PMCID: PMC7490630 DOI: 10.1155/2020/3108490] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 07/22/2020] [Accepted: 08/17/2020] [Indexed: 11/17/2022] Open
Abstract
Background Cochlear implant-based electrical stimulation may be an important reason to induce the residual hearing loss after cochlear implantation. In our previous study, we found that charge-balanced biphasic electrical stimulation inhibited the neurite growth of spiral ganglion neurons (SGNs) and decreased Schwann cell density in vitro. In this study, we want to know whether cochlear implant-based electrical stimulation can induce the change of electrical activity in cultured SGNs. Methods Spiral ganglion neuron electrical stimulation in vitro model is established using the devices delivering cochlear implant-based electrical stimulation. After 48 h treatment by 50 μA or 100 μA electrical stimulation, the action potential (AP) and voltage depended calcium current (I Ca) of SGNs are recorded using whole-cell electrophysiological method. Results The results show that the I Ca of SGNs is decreased significantly in 50 μA and 100 μA electrical stimulation groups. The reversal potential of I Ca is nearly +80 mV in control SGN, but the reversal potential decreases to +50 mV in 50 μA and 100 μA electrical stimulation groups. Interestingly, the AP amplitude, the AP latency, and the AP duration of SGNs have no statistically significant differences in all three groups. Conclusion Our study suggests cochlear implant-based electrical stimulation only significantly inhibit the I Ca of cultured SGNs but has no effect on the firing of AP, and the relation of I Ca inhibition and SGN damage induced by electrical stimulation and its mechanism needs to be further studied.
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Affiliation(s)
- Na Shen
- Department of Otolaryngology, Zhongshan Hospital, Fudan University, Shanghai, China
- ENT Institute and Department of Otolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, China
| | - Lei Zhou
- Department of Otolaryngology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Bin Lai
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Shufeng Li
- ENT Institute and Department of Otolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, China
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11
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Frick C, Fink S, Schmidbauer D, Rousset F, Eickhoff H, Tropitzsch A, Kramer B, Senn P, Glueckert R, Rask-Andersen H, Wiesmüller KH, Löwenheim H, Müller M. Age-Dependency of Neurite Outgrowth in Postnatal Mouse Cochlear Spiral Ganglion Explants. Brain Sci 2020; 10:brainsci10090580. [PMID: 32839381 PMCID: PMC7564056 DOI: 10.3390/brainsci10090580] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 08/18/2020] [Accepted: 08/19/2020] [Indexed: 12/22/2022] Open
Abstract
Background: The spatial gap between cochlear implants (CIs) and the auditory nerve limits frequency selectivity as large populations of spiral ganglion neurons (SGNs) are electrically stimulated synchronously. To improve CI performance, a possible strategy is to promote neurite outgrowth toward the CI, thereby allowing a discrete stimulation of small SGN subpopulations. Brain-derived neurotrophic factor (BDNF) is effective to stimulate neurite outgrowth from SGNs. Method: TrkB (tropomyosin receptor kinase B) agonists, BDNF, and five known small-molecule BDNF mimetics were tested for their efficacy in stimulating neurite outgrowth in postnatal SGN explants. To modulate Trk receptor-mediated effects, TrkB and TrkC ligands were scavenged by an excess of recombinant receptor proteins. The pan-Trk inhibitor K252a was used to block Trk receptor actions. Results: THF (7,8,3′-trihydroxyflavone) partly reproduced the BDNF effect in postnatal day 7 (P7) mouse cochlear spiral ganglion explants (SGEs), but failed to show effectiveness in P4 SGEs. During the same postnatal period, spontaneous and BDNF-stimulated neurite outgrowth increased. The increased neurite outgrowth in P7 SGEs was not caused by the TrkB/TrkC ligands, BDNF and neurotrophin-3 (NT-3). Conclusions: The age-dependency of induction of neurite outgrowth in SGEs was very likely dependent on presently unidentified factors and/or molecular mechanisms which may also be decisive for the age-dependent efficacy of the small-molecule TrkB receptor agonist THF.
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Affiliation(s)
- Claudia Frick
- Department of Otolaryngology, Head and Neck Surgery, Tübingen Hearing Research Centre, University of Tübingen Medical Center, 72076 Tübingen, Germany; (C.F.); (A.T.); (B.K.); (H.L.); (M.M.)
- Department of Microbiome Science, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | - Stefan Fink
- Department of Otolaryngology, Head and Neck Surgery, Tübingen Hearing Research Centre, University of Tübingen Medical Center, 72076 Tübingen, Germany; (C.F.); (A.T.); (B.K.); (H.L.); (M.M.)
- Correspondence: ; Tel.: +49-7071-2988192
| | - Dominik Schmidbauer
- Inner Ear Laboratory Innsbruck, Medical University Innsbruck, 6020 Innsbruck, Austria; (D.S.); (R.G.)
| | - Francis Rousset
- The Inner Ear & Olfaction Lab, Department of Clinical Neurosciences, Faculty of Medicine, University of Geneva, 1206 Geneva, Switzerland; (F.R.); (P.S.)
| | - Holger Eickhoff
- EMC Microcollections GmbH, 72070 Tübingen, Germany; (H.E.); (K.-H.W.)
| | - Anke Tropitzsch
- Department of Otolaryngology, Head and Neck Surgery, Tübingen Hearing Research Centre, University of Tübingen Medical Center, 72076 Tübingen, Germany; (C.F.); (A.T.); (B.K.); (H.L.); (M.M.)
| | - Benedikt Kramer
- Department of Otolaryngology, Head and Neck Surgery, Tübingen Hearing Research Centre, University of Tübingen Medical Center, 72076 Tübingen, Germany; (C.F.); (A.T.); (B.K.); (H.L.); (M.M.)
- Department of Otolaryngology, Head and Neck Surgery, University Hospital Mannheim, 68167 Mannheim, Germany
| | - Pascal Senn
- The Inner Ear & Olfaction Lab, Department of Clinical Neurosciences, Faculty of Medicine, University of Geneva, 1206 Geneva, Switzerland; (F.R.); (P.S.)
| | - Rudolf Glueckert
- Inner Ear Laboratory Innsbruck, Medical University Innsbruck, 6020 Innsbruck, Austria; (D.S.); (R.G.)
- Tirol Kliniken Innsbruck, University Clinic of Otolaryngology, 6020 Innsbruck, Austria
| | - Helge Rask-Andersen
- Department of Surgical Sciences, Otorhinolaryngology and Head and Neck Surgery, University of Uppsala, 751 85 Uppsala, Sweden;
| | | | - Hubert Löwenheim
- Department of Otolaryngology, Head and Neck Surgery, Tübingen Hearing Research Centre, University of Tübingen Medical Center, 72076 Tübingen, Germany; (C.F.); (A.T.); (B.K.); (H.L.); (M.M.)
| | - Marcus Müller
- Department of Otolaryngology, Head and Neck Surgery, Tübingen Hearing Research Centre, University of Tübingen Medical Center, 72076 Tübingen, Germany; (C.F.); (A.T.); (B.K.); (H.L.); (M.M.)
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12
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Consecutive Treatment with Brain-Derived Neurotrophic Factor and Electrical Stimulation Has a Protective Effect on Primary Auditory Neurons. Brain Sci 2020; 10:brainsci10080559. [PMID: 32824176 PMCID: PMC7464901 DOI: 10.3390/brainsci10080559] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/12/2020] [Accepted: 08/13/2020] [Indexed: 01/27/2023] Open
Abstract
Degeneration of neurons, such as the inner ear spiral ganglion neurons (SGN), may be decelerated or even stopped by neurotrophic factor treatment, such as brain-derived neurotrophic factor (BDNF), as well as electrical stimulation (ES). In a clinical setting, drug treatment of the SGN could start directly during implantation of a cochlear implant, whereas electrical stimulation begins days to weeks later. The present study was conducted to determine the effects of consecutive BDNF and ES treatments on SGN density and electrical responsiveness. An electrode drug delivery device was implanted in guinea pigs 3 weeks after deafening and five experimental groups were established: two groups received intracochlear infusion of artificial perilymph (AP) or BDNF; two groups were treated with AP respectively BDNF in addition to ES (AP + ES, BDNF + ES); and one group received BDNF from the day of implantation until day 34 followed by ES (BDNF ⇨ ES). Electrically evoked auditory brainstem responses were recorded. After one month of treatment, the tissue was harvested and the SGN density was assessed. The results show that consecutive treatment with BDNF and ES was as successful as the simultaneous combined treatment in terms of enhanced SGN density compared to the untreated contralateral side but not in regard to the numbers of protected cells.
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13
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Bennison SA, Blazejewski SM, Smith TH, Toyo-Oka K. Protein kinases: master regulators of neuritogenesis and therapeutic targets for axon regeneration. Cell Mol Life Sci 2020; 77:1511-1530. [PMID: 31659414 PMCID: PMC7166181 DOI: 10.1007/s00018-019-03336-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 09/16/2019] [Accepted: 10/08/2019] [Indexed: 12/25/2022]
Abstract
Proper neurite formation is essential for appropriate neuronal morphology to develop and defects at this early foundational stage have serious implications for overall neuronal function. Neuritogenesis is tightly regulated by various signaling mechanisms that control the timing and placement of neurite initiation, as well as the various processes necessary for neurite elongation to occur. Kinases are integral components of these regulatory pathways that control the activation and inactivation of their targets. This review provides a comprehensive summary of the kinases that are notably involved in regulating neurite formation, which is a complex process that involves cytoskeletal rearrangements, addition of plasma membrane to increase neuronal surface area, coupling of cytoskeleton/plasma membrane, metabolic regulation, and regulation of neuronal differentiation. Since kinases are key regulators of these functions during neuromorphogenesis, they have high potential for use as therapeutic targets for axon regeneration after injury or disease where neurite formation is disrupted.
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Affiliation(s)
- Sarah A Bennison
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, 19129, USA
| | - Sara M Blazejewski
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, 19129, USA
| | - Trevor H Smith
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, 19129, USA
| | - Kazuhito Toyo-Oka
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, 19129, USA.
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14
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Gonmanee T, Sritanaudomchai H, Vongsavan K, Faisaikarm T, Songsaad A, White KL, Thonabulsombat C. Neuronal differentiation of dental pulp stem cells from human permanent and deciduous teeth following coculture with rat auditory brainstem slices. Anat Rec (Hoboken) 2020; 303:2931-2946. [PMID: 31930687 DOI: 10.1002/ar.24368] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 10/18/2019] [Accepted: 11/27/2019] [Indexed: 01/01/2023]
Abstract
Sensorineural hearing loss is a common disability found worldwide which is associated with a degeneration of spiral ganglion neurons (SGN). It is a challenge to restore SGN due to the permanent degeneration and viability of SGN is requisite for patients to receive an advantage from hearing aid devices. Human dental pulp stem cells (DPSC) and stem cells from human exfoliated deciduous teeth (SHED) are self-renewing stem cells that originate from the neural crest during development. These stem cells have a high potential for neuronal differentiation. This is primarily due to their multilineage differentiation potential and their relative ease of access. Previously, we have shown the ability of these stem cell types to differentiate into spiral ganglion neuron-like cells. In this study, we induced the cells into neural precursor cells (NPC) and cocultured with auditory brainstem slice (ABS) encompassing cochlear nucleus by the Stoppini method. We also investigated their ability to differentiate after 2 weeks and 4 weeks in coculture. Neuronal differentiation of DPSC-NPC and SHED-NPC was higher expression of specific markers to SGN, TrkB, and Gata3, compared to monoculture. The cells also highly expressed synaptic vesicle protein (SV2A) and exhibited intracellular calcium oscillations. Our findings demonstrated the possibility of using DPSCs and SHEDs as an autologous stem cell-based therapy for sensorineural hearing loss patients.
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Affiliation(s)
- Thanasup Gonmanee
- Department of Anatomy, Faculty of Science, Mahidol University, Bangkok, Thailand
| | | | - Kutkao Vongsavan
- Department of Pediatric Dentistry, International College of Dentistry, Walailak University, Bangkok, Thailand
| | - Tassanee Faisaikarm
- Reproductive Research Group, Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, Thailand
| | - Anupong Songsaad
- Department of Anatomy, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Kenneth L White
- Department of Animal, Dairy, and Veterinary Sciences, College of Agriculture and Applied Sciences, Utah State University, Logan, Utah, USA
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15
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Liang Q, Shen N, Lai B, Xu C, Sun Z, Wang Z, Li S. Electrical Stimulation Degenerated Cochlear Synapses Through Oxidative Stress in Neonatal Cochlear Explants. Front Neurosci 2019; 13:1073. [PMID: 31680814 PMCID: PMC6803620 DOI: 10.3389/fnins.2019.01073] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 09/24/2019] [Indexed: 11/30/2022] Open
Abstract
Neurostimulation devices use electrical stimulation (ES) to substitute, supplement or modulate neural function. However, the impact of ES on their modulating structures is largely unknown. For example, recipients of cochlear implants using electroacoustic stimulation experienced delayed loss of residual hearing over time after ES, even though ES had no impact on the morphology of hair cells. In this study, using a novel model of cochlear explant culture with charge-balanced biphasic ES, we found that ES did not change the quantity and morphology of hair cells but decreased the number of inner hair cell (IHC) synapses and the density of spiral ganglion neuron (SGN) peripheral fibers. Inhibiting calcium influx with voltage-dependent calcium channel (VDCC) blockers attenuated the loss of SGN peripheral fibers and IHC synapses induced by ES. ES increased ROS/RNS in cochlear explants, but the inhibition of calcium influx abolished this effect. Glutathione peroxidase 1 (GPx1) and GPx2 in cochlear explants decreased under ES and ebselen abolished this effect and attenuated the loss of SGN peripheral fibers. This finding demonstrated that ES induced the degeneration of SGN peripheral fibers and IHC synapses in a current intensity- and duration-dependent manner in vitro. Calcium influx resulting in oxidative stress played an important role in this process. Additionally, ebselen might be a potential protector of ES-induced cochlear synaptic degeneration.
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Affiliation(s)
- Qiong Liang
- Department of Otolaryngology, Eye and ENT Hospital of Fudan University, Shanghai, China.,National Health Commission Key Laboratory of Hearing Medicine, Shanghai, China
| | - Na Shen
- Department of Otolaryngology, Eye and ENT Hospital of Fudan University, Shanghai, China.,National Health Commission Key Laboratory of Hearing Medicine, Shanghai, China.,Department of Otolaryngology, Zhongshan Hospital of Fudan University, Shanghai, China
| | - Bin Lai
- State Key Laboratory of Medical Neurobiology, Shanghai, China
| | - Changjian Xu
- Shanghai Cochlear Engineering Technology Research Center, Shanghai, China
| | - Zengjun Sun
- Shanghai Cochlear Engineering Technology Research Center, Shanghai, China
| | - Zhengmin Wang
- Department of Otolaryngology, Eye and ENT Hospital of Fudan University, Shanghai, China.,National Health Commission Key Laboratory of Hearing Medicine, Shanghai, China
| | - Shufeng Li
- Department of Otolaryngology, Eye and ENT Hospital of Fudan University, Shanghai, China.,National Health Commission Key Laboratory of Hearing Medicine, Shanghai, China
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16
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AAV-Mediated Neurotrophin Gene Therapy Promotes Improved Survival of Cochlear Spiral Ganglion Neurons in Neonatally Deafened Cats: Comparison of AAV2-hBDNF and AAV5-hGDNF. J Assoc Res Otolaryngol 2019; 20:341-361. [PMID: 31222416 PMCID: PMC6646500 DOI: 10.1007/s10162-019-00723-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 04/15/2019] [Indexed: 01/22/2023] Open
Abstract
Outcomes with contemporary cochlear implants (CI) depend partly upon the survival and condition of the cochlear spiral ganglion (SG) neurons. Previous studies indicate that CI stimulation can ameliorate SG neural degeneration after deafness, and brain-derived neurotrophic factor (BDNF) delivered by an osmotic pump can further improve neural survival. However, direct infusion of BDNF elicits undesirable side effects, and osmotic pumps are impractical for clinical application. In this study, we explored the potential for two adeno-associated viral vectors (AAV) to elicit targeted neurotrophic factor expression in the cochlea and promote improved SG and radial nerve fiber survival. Juvenile cats were deafened prior to hearing onset by systemic aminoglycoside injections. Auditory brainstem responses showed profound hearing loss by 16-18 days postnatal. At ~ 4 weeks of age, AAV2-GFP (green fluorescent protein), AAV5-GFP, AAV2-hBDNF, or AAV5-hGDNF (glial-derived neurotrophic factor) was injected through the round window unilaterally. For GFP immunofluorescence, animals were studied ~ 4 weeks post-injection to assess cell types transfected and their distributions. AAV2-GFP immunofluorescence demonstrated strong expression of the GFP reporter gene in residual inner (IHCs), outer hair cells (OHCs), inner pillar cells, and in some SG neurons throughout the cochlea. AAV5-GFP elicited robust transduction of IHCs and some SG neurons, but few OHCs and supporting cells. After AAV-neurotrophic factor injections, animals were studied ~ 3 months post-injection to evaluate neural survival. AAV5-hGDNF elicited a modest neurotrophic effect, with 6 % higher SG density, but had no trophic effect on radial nerve fiber survival, and undesirable ectopic fiber sprouting occurred. AAV2-hBDNF elicited a similar 6 % increase in SG survival, but also resulted in greatly improved radial nerve fiber survival, with no ectopic fiber sprouting. A further study assessed whether AAV2-hBDNF neurotrophic effects would persist over longer post-injection periods. Animals examined 6 months after virus injection showed substantial neurotrophic effects, with 14 % higher SG density and greatly improved radial nerve fiber survival. Our results suggest that AAV-neurotrophin gene therapy can elicit expression of physiological concentrations of neurotrophins in the cochlea, supporting improved SG neuronal and radial nerve fiber survival while avoiding undesirable side effects. These studies also demonstrate the potential for application of cochlear gene therapy in a large mammalian cochlea comparable to the human cochlea and in an animal model of congenital/early acquired deafness.
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17
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Scheper V, Schwieger J, Hamm A, Lenarz T, Hoffmann A. BDNF-overexpressing human mesenchymal stem cells mediate increased neuronal protection in vitro. J Neurosci Res 2019; 97:1414-1429. [PMID: 31257632 PMCID: PMC6772136 DOI: 10.1002/jnr.24488] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 05/31/2019] [Accepted: 06/12/2019] [Indexed: 12/21/2022]
Abstract
The use of neurotrophic factors as therapeutic agents for neurodegenerative diseases is considered as an approach aimed at restoring and maintaining neuronal function in the peripheral and central nervous system. Since the neuroprotective effect is depending on chronic delivery of the neurotrophic factors a sustained application, e.g., via cell‐based delivery is necessary. Human mesenchymal stem cells (hMSCs) were lentivirally modified to overexpress brain‐derived neurotrophic factor (BDNF) and to express fluorescent marker genes for easy visualization. Since genetically modified cells should be site‐specifically retained (e.g., by encapsulation) in the patients to avoid adverse effects the cells were additionally differentiated to chondrocytes to hypothetically improve their vitality and survival in a delivery matrix. Different polycations for lentiviral transduction were investigated for their efficiency. The success of differentiation was determined by analysis of chondrocyte marker genes and the neuroprotective effect of BDNF‐overexpressing cells was exemplarily investigated on neurons of the peripheral auditory system. The genetically modified hMSCs overexpressed BDNF from under 1 to 125 ng ml−1 day−1 depending on the donor and transfection method. Using protamine sulfate the transfection efficacy was superior compared to the use of polybrene. The BDNF secreted by the MSCs was significantly neuroprotective in comparison to the relevant controls even though the produced mean concentrations were lower than the effective concentrations for recombinant industrially produced proteins described in literature. The presented system of BDNF‐overexpressing hMSCs is neuroprotective and is therefore considered as a promising method for sustained delivery of proteins in therapeutically relevant amounts to degenerating neuronal structures.
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Affiliation(s)
- Verena Scheper
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany.,Cluster of Excellence Hearing4all, German Research Foundation, Hannover, Germany.,Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany
| | - Jana Schwieger
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany.,Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany
| | - Anika Hamm
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany.,Department of Orthopaedic Surgery, Hannover Medical School, Hannover, Germany
| | - Thomas Lenarz
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany.,Cluster of Excellence Hearing4all, German Research Foundation, Hannover, Germany.,Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany
| | - Andrea Hoffmann
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany.,Department of Orthopaedic Surgery, Hannover Medical School, Hannover, Germany
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18
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Scheper V, Hoffmann A, Gepp MM, Schulz A, Hamm A, Pannier C, Hubka P, Lenarz T, Schwieger J. Stem Cell Based Drug Delivery for Protection of Auditory Neurons in a Guinea Pig Model of Cochlear Implantation. Front Cell Neurosci 2019; 13:177. [PMID: 31139049 PMCID: PMC6527816 DOI: 10.3389/fncel.2019.00177] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 04/12/2019] [Indexed: 01/04/2023] Open
Abstract
Background: The success of a cochlear implant (CI), which is the standard therapy for patients suffering from severe to profound sensorineural hearing loss, depends on the number and excitability of spiral ganglion neurons (SGNs). Brain-derived neurotrophic factor (BDNF) has a protective effect on SGNs but should be applied chronically to guarantee their lifelong survival. Long-term administration of BDNF could be achieved using genetically modified mesenchymal stem cells (MSCs), but these cells should be protected – by ultra-high viscous (UHV-) alginate (‘alginate-MSCs’) – from the recipient immune system and from uncontrolled migration. Methods: Brain-derived neurotrophic factor-producing MSCs were encapsulated in UHV-alginate. Four experimental groups were investigated using guinea pigs as an animal model. Three of them were systemically deafened and (unilaterally) received one of the following: (I) a CI; (II) an alginate-MSC-coated CI; (III) an injection of alginate-embedded MSCs into the scala tympani followed by CI insertion and alginate polymerization. Group IV was normal hearing, with CI insertion in both ears and a unilateral injection of alginate-MSCs. Using acoustically evoked auditory brainstem response measurements, hearing thresholds were determined before implantation and before sacrificing the animals. Electrode impedance was measured weekly. Four weeks after implantation, the animals were sacrificed and the SGN density and degree of fibrosis were evaluated. Results: The MSCs survived being implanted for 4 weeks in vivo. Neither the alginate-MSC injection nor the coating affected electrode impedance or fibrosis. CI insertion with and without previous alginate injection in normal-hearing animals resulted in increased hearing thresholds within the high-frequency range. Low-frequency hearing loss was additionally observed in the alginate-injected and implanted cochleae, but not in those treated only with a CI. In deafened animals, the alginate-MSC coating of the CI significantly prevented SGN from degeneration, but the injection of alginate-MSCs did not. Conclusion: Brain-derived neurotrophic factor-producing MSCs encapsulated in UHV-alginate prevent SGNs from degeneration in the form of coating on the CI surface, but not in the form of an injection. No increase in fibrosis or impedance was detected. Further research and development aimed at verifying long-term mechanical and biological properties of coated electrodes in vitro and in vivo, in combination with chronic electrical stimulation, is needed before the current concept can be tested in clinical trials.
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Affiliation(s)
- Verena Scheper
- Department of Otolaryngology, Hannover Medical School, Hanover, Germany.,Cluster of Excellence 'Hearing4all', German Research Foundation, Bonn, Germany.,Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hanover, Germany
| | - Andrea Hoffmann
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hanover, Germany.,Department of Orthopaedic Surgery, Hannover Medical School, Hanover, Germany
| | - Michael M Gepp
- Fraunhofer Institute for Biomedical Engineering IBMT, Sulzbach, Germany.,Fraunhofer Project Center for Stem Cell Process Engineering, Würzburg, Germany
| | - André Schulz
- Fraunhofer Institute for Biomedical Engineering IBMT, Sulzbach, Germany
| | - Anika Hamm
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hanover, Germany.,Department of Orthopaedic Surgery, Hannover Medical School, Hanover, Germany
| | - Christoph Pannier
- Department of Otolaryngology, Hannover Medical School, Hanover, Germany
| | - Peter Hubka
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hanover, Germany.,Department of Experimental Otology, Hannover Medical School, Hanover, Germany
| | - Thomas Lenarz
- Department of Otolaryngology, Hannover Medical School, Hanover, Germany.,Cluster of Excellence 'Hearing4all', German Research Foundation, Bonn, Germany.,Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hanover, Germany
| | - Jana Schwieger
- Department of Otolaryngology, Hannover Medical School, Hanover, Germany.,Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hanover, Germany
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19
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Wong VSC, Meadows M, Goldberg D, Willis DE. Semaphorin 3A induces acute changes in membrane excitability in spiral ganglion neurons in vitro. Eur J Neurosci 2019; 50:1741-1758. [PMID: 30706560 DOI: 10.1111/ejn.14360] [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: 07/20/2018] [Revised: 01/10/2019] [Accepted: 01/23/2019] [Indexed: 11/29/2022]
Abstract
The development and survival of spiral ganglion neurons (SGNs) are dependent on multiple trophic factors as well as membrane electrical activity. Semaphorins (Sema) constitute a family of membrane-associated and secreted proteins that have garnered significant attention as a potential SGN "navigator" during cochlea development. Previous studies using mutant mice demonstrated that Sema3A plays a role in the SGN pathfinding. The mechanisms, however, by which Sema3A shapes SGNs firing behavior are not known. In these studies, we found that Sema3A plays a novel role in regulating SGN resting membrane potential and excitability. Using dissociated SGN from pre-hearing (P3-P5) and post-hearing mice (P12-P15), we recorded membrane potentials using whole-cell patch clamp recording techniques in apical and basal SGN populations. Recombinant Sema3A was applied to examine the effects on intrinsic membrane properties and action potentials evoked by current injections. Apical and basal SGNs from newborn mice treated with recombinant Sema3A (100 ng/ml) displayed a higher resting membrane potential, higher threshold, decreased amplitude, and prolonged latency and duration of spikes. Although a similar phenomenon was observed in SGNs from post-hearing mice, the resting membrane potential was essentially indistinguishable before and after Sema3A exposure. Sema3A-mediated changes in membrane excitability were associated with a significant decrease in K+ and Ca2+ currents. Sema3A acts through linopirdine-sensitive K+ channels in apical, but not in the basal SGNs. Therefore, Sema3A induces differential effects in SGN membrane excitability that are dependent on age and location, and constitutes an additional early and novel effect of Sema3A SGNs in vitro.
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Affiliation(s)
| | - Marc Meadows
- The Vollum Institute, Oregon Health and Science University, Portland, Oregon
| | - David Goldberg
- The Burke Neurological Institute, White Plains, New York
| | - Dianna E Willis
- The Burke Neurological Institute, White Plains, New York.,Brain and Mind Research Institute, Weill Cornell Medicine, New York, New York
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Yang T, Choi JE, Soh D, Tobin K, Joiner ML, Hansen M, Lee A. CaBP1 regulates Ca v1 L-type Ca 2+ channels and their coupling to neurite growth and gene transcription in mouse spiral ganglion neurons. Mol Cell Neurosci 2018; 88:342-352. [PMID: 29548764 DOI: 10.1016/j.mcn.2018.03.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Revised: 03/07/2018] [Accepted: 03/12/2018] [Indexed: 12/19/2022] Open
Abstract
CaBP1 is a Ca2+ binding protein that is widely expressed in neurons in the brain, retina, and cochlea. In heterologous expression systems, CaBP1 interacts with and regulates voltage-gated Cav Ca2+ channels but whether this is the case in neurons is unknown. Here, we investigated the cellular functions of CaBP1 in cochlear spiral ganglion neurons (SGNs), which express high levels of CaBP1. Consistent with the role of CaBP1 as a suppressor of Ca2+-dependent inactivation (CDI) of Cav1 (L-type) channels, Cav1 currents underwent greater CDI in SGNs from mice lacking CaBP1 (C-KO) than in wild-type (WT) SGNs. The coupling of Cav1 channels to downstream signaling pathways was also disrupted in C-KO SGNs. Activity-dependent repression of neurite growth was significantly blunted and unresponsive to Cav1 antagonists in C-KO SGNs in contrast to WT SGNs. Moreover, Cav1-mediated Ca2+ signals and phosphorylation of cAMP-response element binding protein were reduced in C-KO SGNs compared to WT SGNs. Our findings establish a role for CaBP1 as an essential regulator of Cav1 channels in SGNs and their coupling to downstream pathways controlling activity-dependent transcription and neurite growth.
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Affiliation(s)
- Tian Yang
- Departments of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA 52242, USA
| | - Ji-Eun Choi
- Departments of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA 52242, USA
| | - Daniel Soh
- Departments of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA 52242, USA
| | - Kevin Tobin
- Departments of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA 52242, USA
| | - Mei-Ling Joiner
- Otolaryngology Head-Neck Surgery, University of Iowa, Iowa City, IA 52242, USA
| | - Marlan Hansen
- Otolaryngology Head-Neck Surgery, University of Iowa, Iowa City, IA 52242, USA; Neurosurgery, University of Iowa, Iowa City, IA 52242, USA
| | - Amy Lee
- Departments of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA 52242, USA; Otolaryngology Head-Neck Surgery, University of Iowa, Iowa City, IA 52242, USA; Neurology, University of Iowa, Iowa City, IA 52242, USA.
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Mitsuoka K, Kikutani T, Miwa Y, Sato I. Expression of CGRP neurotransmitter and vascular genesis marker mRNA is age-dependent in superior cervical ganglia of senescence-accelerated prone mice. Neurosci Lett 2018; 664:144-151. [PMID: 29154859 DOI: 10.1016/j.neulet.2017.11.034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 10/30/2017] [Accepted: 11/13/2017] [Indexed: 11/30/2022]
Abstract
Calcitonin gene-related peptide (CGRP) is a neurotransmitter that is released from the superior cervical ganglion (SCG) and causes head and neck pain. The morphological properties of human SCG neurons, including neurotransmitter content, are altered during aging. However, morphological changes in CGRP in the SCG during aging are not known. Therefore, we investigated CGRP and other markers in the SCG during aging in an aging model of senescence-accelerated prone mouse (SAMP8) and senescence-accelerated resistant mice (SAMR1) using real-time RT-PCR mRNA analyses and in situ hybridization. The abundance of neurotransmitter (CGRP, NPY, TRPV1), vascular genesis marker (CD31, LYVE-1), and cytochrome C mRNA differed between 12-week-old and 24-week-old SAMP8 and SAMR1. Abundance of TRPV1, CD31 and cytochrome C mRNAs of SAMP8 decreased between 12- and 24-week-old. The ratio of CGRP mRNA positive cells and CGRP mRNA abundance levels of the SCG of aging mouse such as SAMP8 have already been also higher than that of SAMR1 at 12-week-old. The CGRP positive shrunken ganglion cells was increased from 12- to 24-weeks-old mouse in SAMR1 and SAMP8. The SCG primarily affected the internal and external carotid arteries, larynx thyroid gland, and pharyngeal muscle during aging.
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Affiliation(s)
- Kazuyuki Mitsuoka
- Department of Anatomy, School of Life Dentistry at Tokyo, The Nippon Dental University, Tokyo, Japan; Division of Oral Rehabilitation, Nippon Dental University Graduate School of Life Dentistry, Tokyo, Japan
| | - Takeshi Kikutani
- Division of Oral Rehabilitation, Nippon Dental University Graduate School of Life Dentistry, Tokyo, Japan; Nippon Dental University Tama Oral Rehabilitation Clinic, Japan
| | - Yoko Miwa
- Department of Anatomy, School of Life Dentistry at Tokyo, The Nippon Dental University, Tokyo, Japan
| | - Iwao Sato
- Department of Anatomy, School of Life Dentistry at Tokyo, The Nippon Dental University, Tokyo, Japan.
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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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Scheper V, Hessler R, Hütten M, Wilk M, Jolly C, Lenarz T, Paasche G. Local inner ear application of dexamethasone in cochlear implant models is safe for auditory neurons and increases the neuroprotective effect of chronic electrical stimulation. PLoS One 2017; 12:e0183820. [PMID: 28859106 PMCID: PMC5578571 DOI: 10.1371/journal.pone.0183820] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 08/11/2017] [Indexed: 01/15/2023] Open
Abstract
Dexamethasone (DEX) can reduce fibrous tissue growth as well as loss of residual hearing which may occur after cochlear implantation. Little is known about the effect of local inner ear DEX treatment on the spiral ganglion neurons (SGN), which are the target of the electrical stimulation with a cochlear implant (CI). Three different clinically relevant strategies of DEX-delivery into the inner ear were used. DEX was either eluted from the electrode carriers' silicone, released from a reservoir by passive diffusion, or actively applied using a pump based system. The effect of the locally applied DEX on SGN density, size and function was evaluated. DEX did not affect the SGN density compared to the relevant control groups. Simultaneously applied with chronic electrical stimulation (ES), DEX increased the neuroprotective effect of ES in the basal region and the hearing threshold tended to decrease. The EABR thresholds did not correlate with the relevant SGN density. When correlating the SGN number with fibrosis, no dependency was observed. DEX concentrations as applied in these animal models are safe for inner ear delivery in terms of their effect on SGN density. Additionally, DEX tends to improve the neuroprotective effect of chronic electrical stimulation by increasing the number of surviving neurons. This is an important finding in regard to clinical applications of DEX for local treatment of the inner ear in view of cochlear implantation and other applications.
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Affiliation(s)
- Verena Scheper
- Hannover Medical School (MHH), Department of Otolaryngology, Hannover, Germany
- Cluster of Excellence Hearing4all, German Research Foundation, Hannover, Germany
- * E-mail:
| | - Roland Hessler
- MED-EL Innsbruck, Research & Development, Innsbruck, Österreich
| | - Mareike Hütten
- Hannover Medical School (MHH), Department of Otolaryngology, Hannover, Germany
| | - Maciej Wilk
- Hannover Medical School (MHH), Department of Otolaryngology, Hannover, Germany
| | - Claude Jolly
- MED-EL Innsbruck, Research & Development, Innsbruck, Österreich
| | - Thomas Lenarz
- Hannover Medical School (MHH), Department of Otolaryngology, Hannover, Germany
- Cluster of Excellence Hearing4all, German Research Foundation, Hannover, Germany
| | - Gerrit Paasche
- Hannover Medical School (MHH), Department of Otolaryngology, Hannover, Germany
- Cluster of Excellence Hearing4all, German Research Foundation, Hannover, Germany
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Leigh BL, Cheng E, Linjing X, Andresen C, Hansen MR, Guymon CA. Photopolymerizable Zwitterionic Polymer Patterns Control Cell Adhesion and Guide Neural Growth. Biomacromolecules 2017; 18:2389-2401. [PMID: 28671816 PMCID: PMC6372952 DOI: 10.1021/acs.biomac.7b00579] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Developing materials that reduce or eliminate fibrosis encapsulation of neural prosthetic implants could significantly enhance implant fidelity by improving the tissue/electrode array interface. Here, we report on the photografting and patterning of two zwitterionic materials, sulfobetaine methacrylate (SBMA) and carboxybetaine methacrylate (CBMA), for controlling the adhesion and directionality of cells relevant to neural prosthetics. CBMA and SBMA polymers were photopolymerized and grafted on glass surfaces then characterized by X-ray photoelectron spectroscopy, water contact angle, and protein adsorption. Micropatterned surfaces were fabricated with alternating zwitterionic and uncoated bands. Fibroblasts, cells prevalent in fibrotic tissue, almost exclusively migrate and grow on uncoated bands with little to no cells present on zwitterionic bands, especially for CBMA-coated surfaces. Astrocytes and Schwann cells showed similarly low levels of cell adhesion and morphology changes when cultured on zwitterionic surfaces. Additionally, Schwann cells and inner ear spiral ganglion neuron neurites aligned well to zwitterionic patterns.
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Affiliation(s)
- Braden L. Leigh
- Department of Chemical and Biochemical Engineering, University of Iowa, Iowa City, IA 52242, USA
| | - Elise Cheng
- Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, USA
| | - Xu Linjing
- Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, USA
| | - Corinne Andresen
- Department of Chemical and Biochemical Engineering, University of Iowa, Iowa City, IA 52242, USA
| | - Marlan R. Hansen
- Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, USA
- Department of Neurosurgery, University of Iowa, Iowa City, IA 52242, USA
| | - C. Allan Guymon
- Department of Chemical and Biochemical Engineering, University of Iowa, Iowa City, IA 52242, USA
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25
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Drug discovery for hearing loss: Phenotypic screening of chemical compounds on primary cultures of the spiral ganglion. Hear Res 2017; 349:177-181. [DOI: 10.1016/j.heares.2016.07.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 07/21/2016] [Accepted: 07/30/2016] [Indexed: 11/23/2022]
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Encapsulated cell device approach for combined electrical stimulation and neurotrophic treatment of the deaf cochlea. Hear Res 2017; 350:110-121. [PMID: 28463804 DOI: 10.1016/j.heares.2017.04.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 03/15/2017] [Accepted: 04/23/2017] [Indexed: 12/21/2022]
Abstract
Profound hearing impairment can be overcome by electrical stimulation (ES) of spiral ganglion neurons (SGNs) via a cochlear implant (CI). Thus, SGN survival is critical for CI efficacy. Application of glial cell line-derived neurotrophic factor (GDNF) has been shown to reduce SGN degeneration following deafness. We tested a novel method for local, continuous GDNF-delivery in combination with ES via a CI. The encapsulated cell (EC) device contained a human ARPE-19 cell-line, genetically engineered for secretion of GDNF. In vitro, GDNF delivery was stable during ES delivered via a CI. In the chronic in vivo part, cats were systemically deafened and unilaterally implanted into the scala tympani with a CI and an EC device, which they wore for six months. The implantation of control devices (same cell-line not producing GDNF) had no negative effect on SGN survival. GDNF application without ES led to an unexpected reduction in SGN survival, however, the combination of GDNF with initial, short-term ES resulted in a significant protection of SGNs. A tight fibrous tissue formation in the scala tympani of the GDNF-only group is thought to be responsible for the increased SGN degeneration, due to mechanisms related to an aggravated foreign body response. Furthermore, the fibrotic encapsulation of the EC device led to cell death or cessation of GDNF release within the EC device during the six months in vivo. In both in vitro and in vivo, fibrosis was reduced by CI stimulation, enabling the neuroprotective effect of the combined treatment. Thus, fibrous tissue growth limits treatment possibilities with an EC device. For a stable and successful long-term neurotrophic treatment of the SGN via EC devices in human CI users, it would be necessary to make changes in the treatment approach (provision of anti-inflammatories), the EC device surface (reduced cell adhesion) and the ES (initiation prior to fibrosis formation).
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Effects of brain-derived neurotrophic factor (BDNF) on the cochlear nucleus in cats deafened as neonates. Hear Res 2016; 342:134-143. [PMID: 27773647 DOI: 10.1016/j.heares.2016.10.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 08/23/2016] [Accepted: 10/15/2016] [Indexed: 01/11/2023]
Abstract
Many previous studies have shown significant neurotrophic effects of intracochlear delivery of BDNF in preventing degeneration of cochlear spiral ganglion (SG) neurons after deafness in rodents and our laboratory has shown similar results in developing cats deafened prior to hearing onset. This study examined the morphology of the cochlear nucleus (CN) in a group of neonatally deafened cats from a previous study in which infusion of BDNF elicited a significant improvement in survival of the SG neurons. Five cats were deafened by systemic injections of neomycin sulfate (60 mg/kg, SQ, SID) starting one day after birth, and continuing for 16-18 days until auditory brainstem response (ABR) testing demonstrated profound bilateral hearing loss. The animals were implanted unilaterally at about 1 month of age using custom-designed electrodes with a drug-delivery cannula connected to an osmotic pump. BDNF (94 μg/ml; 0.25 μl/hr) was delivered for 10 weeks. The animals were euthanized and studied at 14-23 weeks of age. Consistent with the neurotrophic effects of BDNF on SG survival, the total CN volume in these animals was significantly larger on the BDNF-treated side than on the contralateral side. However, total CN volume, both ipsi- and contralateral to the implants in these deafened juvenile animals, was markedly smaller than the CN in normal adult animals, reflecting the severe effects of deafness on the central auditory system during development. Data from the individual major CN subdivisions (DCN, Dorsal Cochlear Nucleus; PVCN, Posteroventral Cochlear Nucleus; AVCN, Anteroventral Cochlear Nucleus) also were analyzed. A significant difference was observed between the BDNF-treated and control sides only in the AVCN. Measurements of the cross-sectional areas of spherical cells showed that cells were significantly larger in the AVCN ipsilateral to the implant than on the contralateral side. Further, the numerical density of spherical cells was significantly lower in the AVCN ipsilateral to the implant than on the contralateral side, consistent with the larger AVCN volume observed with BDNF treatment. Together, findings indicate significant neurotrophic effects of intracochlear BDNF infusion on the developing CN.
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28
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Schwieger J, Esser KH, Lenarz T, Scheper V. Establishment of a long-term spiral ganglion neuron culture with reduced glial cell number: Effects of AraC on cell composition and neurons. J Neurosci Methods 2016; 268:106-16. [DOI: 10.1016/j.jneumeth.2016.05.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 04/29/2016] [Accepted: 05/02/2016] [Indexed: 01/13/2023]
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Charge-balanced biphasic electrical stimulation inhibits neurite extension of spiral ganglion neurons. Neurosci Lett 2016; 624:92-9. [DOI: 10.1016/j.neulet.2016.04.069] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 04/17/2016] [Accepted: 04/28/2016] [Indexed: 11/23/2022]
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Li S, Tuft B, Xu L, Polacco M, Clarke JC, Guymon CA, Hansen MR. Intracellular calcium and cyclic nucleotide levels modulate neurite guidance by microtopographical substrate features. J Biomed Mater Res A 2016; 104:2037-48. [PMID: 27062708 DOI: 10.1002/jbm.a.35738] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 03/29/2016] [Accepted: 04/05/2016] [Indexed: 02/06/2023]
Abstract
Micro- and nanoscale surface features have emerged as potential tools to direct neurite growth into close proximity with next generation neural prosthesis electrodes. However, the signaling events underlying the ability of growth cones to respond to topographical features remain largely unknown. Accordingly, this study probes the influence of [Ca(2+) ]i and cyclic nucleotide levels on the ability of neurites from spiral ganglion neurons (SGNs) to precisely track topographical micropatterns. Photopolymerization and photomasking were used to generate micropatterned methacrylate polymer substrates. Dissociated SGN cultures were plated on the micropatterned surfaces. Calcium influx and release from internal stores were manipulated by elevating extracellular K(+) , maintenance in calcium-free media, or bath application of various calcium channel blockers. Cyclic nucleotide activity was increased by application of cpt-cAMP or 8-Br-cGMP. Elevation of [Ca(2+) ]i by treatment of cultures with elevated potassium reduced neurite alignment to physical microfeatures. Maintenance of cultures in Ca(2+) -free medium or treatment with the non-selective voltage-gated calcium channel blocker cadmium or L-type Ca(2+) channel blocker nifedipine did not signficantly alter SGN neurite alignment. By contrast, ryanodine or xestospongin C, which block release of internal calcium stores via ryanodine-sensitive channels or inositol-1,4,5-trisphosphate receptors respectively, each significantly decreased neurite alignment. Cpt-cAMP significantly reduced neurite alignment while 8-Br-cGMP significantly enhanced neurite alignment. Manipulation of [Ca(2+) ]i or cAMP levels significantly disrupts neurite guidance while elevation of cGMP levels increases neurite alignment. The results suggest intracellular signaling pathways similar to those recruited by chemotactic cues are involved in neurite guidance by topographical features. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2037-2048, 2016.
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Affiliation(s)
- Shufeng Li
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa, 52242.,Department of Otolaryngology, Eye & ENT Hospital of Fudan University, Shanghai, 200031, China
| | - Bradley Tuft
- Department of Chemical and Biochemical Engineering, University of Iowa, Iowa City, Iowa, 52242
| | - Linjing Xu
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa, 52242
| | - Marc Polacco
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa, 52242
| | - Joseph C Clarke
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa, 52242
| | - C Allan Guymon
- Department of Chemical and Biochemical Engineering, University of Iowa, Iowa City, Iowa, 52242
| | - Marlan R Hansen
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa, 52242.,Department of Neurosurgery, University of Iowa, Iowa City, Iowa, 52242
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31
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Lee J, Han K, Song JJ, Im GJ, Chae SW. Sarcopenia and Hearing Loss in Older Koreans: Findings from the Korea National Health and Nutrition Examination Survey (KNHANES) 2010. PLoS One 2016; 11:e0150281. [PMID: 26978776 PMCID: PMC4792432 DOI: 10.1371/journal.pone.0150281] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 02/11/2016] [Indexed: 12/20/2022] Open
Abstract
Age-related hearing impairment (ARHI) is becoming a more significant issue as geriatric population increases. Sarcopenia in older people is known to have a diverse health problem in various circumstances in recent studies. We assessed whether the decrease in muscle mass is related to ARHI. We used the 2010 data of the Korea National Health and Nutrition Examination Survey (KNHANES) to examine the associations between sarcopenia and ARHI. A total number of participants was 1,622 including 746 males and 876 females aged 60 years or older. Muscle mass was assessed as an appendicular skeletal muscle mass, and hearing loss was defined as the pure-tone averages (PTA) of test frequencies 0.5, 1, 2, 4 kHz at a threshold of 40 dB or higher in worse hearing side of the ear. Among 1,622 participants, 298 men and 256 women had hearing loss. Appendicular muscle mass (ASM), expressed as kg, was categorized in tertiles. In female population, after adjusting for age, smoking, drinking, amount of exercise, total body fat, education level, income level, and tinnitus, the odds ratio (OR) for hearing loss was 1.57 (95% confidence interval (CI) = 0.92–2.68) in the middle tertile and 1.79 (1.03–3.08) in the lowest tertile, compared with the highest tertile. P for trend in this model was 0.036. Controlling further for hypertension, diabetes mellitus, chronic kidney disease, and three types of noise exposure did not change the association. Larger muscle mass is associated with lower prevalence of hearing loss in elderly Korean females.
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Affiliation(s)
- Jieun Lee
- School of Medicine, Korea University, Seoul, Korea
| | - Kyungdo Han
- Department of Biostatistics, Catholic University of Korea, School of Medicine, Seoul, Korea
| | - Jae Jun Song
- Department of Otolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, Korea
| | - Gi Jung Im
- Department of Otolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, Korea
| | - Sung Won Chae
- Department of Otolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, Korea
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Cheng EL, Leigh B, Guymon CA, Hansen MR. Quantifying Spiral Ganglion Neurite and Schwann Behavior on Micropatterned Polymer Substrates. Methods Mol Biol 2016; 1427:305-18. [PMID: 27259935 DOI: 10.1007/978-1-4939-3615-1_18] [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] [Indexed: 12/12/2022]
Abstract
The first successful in vitro experiments on the cochlea were conducted in 1928 by Honor Fell (Fell, Arch Exp Zellforsch 7(1):69-81, 1928). Since then, techniques for culture of this tissue have been refined, and dissociated primary culture of the spiral ganglion has become a widely accepted in vitro model for studying nerve damage and regeneration in the cochlea. Additionally, patterned substrates have been developed that facilitate and direct neural outgrowth. A number of automated and semi-automated methods for quantifying this neurite outgrowth have been utilized in recent years (Zhang et al., J Neurosci Methods 160(1):149-162, 2007; Tapias et al., Neurobiol Dis 54:158-168, 2013). Here, we describe a method to study the effect of topographical cues on spiral ganglion neurite and Schwann cell alignment. We discuss our microfabrication process, characterization of pattern features, cell culture techniques for both spiral ganglion neurons and spiral ganglion Schwann cells. In addition, we describe protocols for reducing fibroblast count, immunocytochemistry, and methods for quantifying neurite and Schwann cell alignment.
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Affiliation(s)
- Elise L Cheng
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA, USA
| | - Braden Leigh
- Department of Chemical and Biochemical Engineering, 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 Hospitals and Clinics, Iowa City, IA, USA. .,Department of Neurosurgery, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, IA, 52242, USA.
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Sameer Mallick A, Qureishi A, Pearson R, O'Donoghue G. Neurotrophins and cochlear implants: a solution to sensorineural deafness? Cochlear Implants Int 2015; 14:158-64. [PMID: 22889496 DOI: 10.1179/1754762812y.0000000013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
OBJECTIVES To review current trends for treating sensorineural deafness by enhancing spiral ganglion neuron (SGN) survival using neurotrophins combined with cochlear implants and identify areas for future research and development. METHODS A literature search was undertaken on PubMed and Google scholar using terms: neurotrophins, cochlear implants (CIs), and sensorineural to identify the most recent and significant publications. The abstracts were read to identify relevant papers; these were accessed in full and analysed for this review. RESULTS Neurotrophins have a known role in cochlear development and the maintenance of SGNs. So far experiments using osmotic pumps to deliver neurotrophins have been successful for short-term enhanced survival of SGN's following aminoglycoside ototoxicity in animal models. They have demonstrated the re-sprouting of radial nerve fibres from SGN's towards the source of delivery. In addition electrical stimulation, gene and cell-based therapy have increased SGN survival to varying degrees. DISCUSSION Osmotic pumps carry a high risk of infection therefore CIs coated in a drug containing polymer or hydrogel are a realistic alternative for sustained delivery of neurotrophins. Increased SGN survival combined with neuronal re-growth raises the possibility for CIs to stimulate discrete SGN populations. Unfortunately, the duration of treatment needed for long-term survival still remains unclear and further work is needed. Nevertheless the combination of regenerative medicine to CI technology presents a novel approach to developing CI technology.
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Abstract
Taurine is an ubiquitary expressed aminosulfonic acid known to play an important role in the development and maintenance of the nervous system. It is distributed in the inner ear, contributing toward the protection of hair cells against aminoglycoside-induced or bilirubin-induced ototoxicity. Thus, the question arises whether taurine also has an influence on the cellular integrity of the auditory neurons. To test this hypothesis, isolated cells of the spiral ganglion were cocultured with taurine or the neurotrophic factors brain derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) as controls. The analysis included cellular survival rate and neurite outgrowth. With application of taurine, the survival of glial cells and neurons was stimulated in a similar pattern, whereas BDNF and NT-3 only effected neuronal survival. Furthermore, administration of taurine resulted in enhanced neurite outgrowth comparable with the effect of the neurotrophic factors. These new insights on the neuromodulatory effects of taurine on auditory neurons suggest the use of this aminosulfonic acid to reduce the degeneration of auditory neurons in sensorineural hearing loss. Consecutively, a new therapeutical approach for the therapy of hearing impairment could be discussed.
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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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36
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Abstract
Severe noise can cause permanent hearing damage. A recent study now shows that the capacity to recover from noise damage varies with time of day, driven by circadian clock control of a nerve growth factor (BDNF) in the inner ear.
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Affiliation(s)
- Andrew S I Loudon
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK.
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Kostic S, Pan B, Guo Y, Yu H, Sapunar D, Kwok WM, Hudmon A, Wu HE, Hogan QH. Regulation of voltage-gated Ca(2+) currents by Ca(2+)/calmodulin-dependent protein kinase II in resting sensory neurons. Mol Cell Neurosci 2014; 62:10-8. [PMID: 25064143 DOI: 10.1016/j.mcn.2014.07.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 06/05/2014] [Accepted: 07/23/2014] [Indexed: 10/25/2022] Open
Abstract
Calcium/calmodulin-dependent protein kinase II (CaMKII) is recognized as a key element in encoding depolarization activity of excitable cells into facilitated voltage-gated Ca(2+) channel (VGCC) function. Less is known about the participation of CaMKII in regulating VGCCs in resting cells. We examined constitutive CaMKII control of Ca(2+) currents in peripheral sensory neurons acutely isolated from dorsal root ganglia (DRGs) of adult rats. The small molecule CaMKII inhibitor KN-93 (1.0μM) reduced depolarization-induced ICa by 16-30% in excess of the effects produced by the inactive homolog KN-92. The specificity of CaMKII inhibition on VGCC function was shown by the efficacy of the selective CaMKII blocking peptide autocamtide-2-related inhibitory peptide in a membrane-permeable myristoylated form, which also reduced VGCC current in resting neurons. Loss of VGCC currents is primarily due to reduced N-type current, as application of mAIP selectively reduced N-type current by approximately 30%, and prior N-type current inhibition eliminated the effect of mAIP on VGCCs, while prior block of L-type channels did not reduce the effect of mAIP on total ICa. T-type currents were not affected by mAIP in resting DRG neurons. Transduction of sensory neurons in vivo by DRG injection of an adeno-associated virus expressing AIP also resulted in a loss of N-type currents. Together, these findings reveal a novel molecular adaptation whereby sensory neurons retain CaMKII support of VGCCs despite remaining quiescent.
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Affiliation(s)
- Sandra Kostic
- Medical College of Wisconsin, Department of Anesthesiology, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
| | - Bin Pan
- Medical College of Wisconsin, Department of Anesthesiology, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
| | - Yuan Guo
- Medical College of Wisconsin, Department of Anesthesiology, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
| | - Hongwei Yu
- Medical College of Wisconsin, Department of Anesthesiology, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
| | - Damir Sapunar
- Department of Anatomy, Histology and Embryology, University of Split School of Medicine, Split, Croatia.
| | - Wai-Meng Kwok
- Medical College of Wisconsin, Department of Anesthesiology, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
| | - Andy Hudmon
- Indiana University School of Medicine, Department of Biochemistry and Molecular Biology, Stark Neuroscience Research Institute, 950 West Walnut (R2-480), Indianapolis, IN 46202, USA.
| | - Hsiang-En Wu
- Medical College of Wisconsin, Department of Anesthesiology, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
| | - Quinn H Hogan
- Medical College of Wisconsin, Department of Anesthesiology, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA; Zablocki VA Medical Center, 5000W. National Avenue, Milwaukee, WI 53295, USA.
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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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Rettenmaier A, Lenarz T, Reuter G. Nanosecond laser pulse stimulation of spiral ganglion neurons and model cells. BIOMEDICAL OPTICS EXPRESS 2014; 5:1014-25. [PMID: 24761285 PMCID: PMC3986005 DOI: 10.1364/boe.5.001014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 12/26/2013] [Accepted: 01/13/2014] [Indexed: 05/18/2023]
Abstract
Optical stimulation of the inner ear has recently attracted attention, suggesting a higher frequency resolution compared to electrical cochlear implants due to its high spatial stimulation selectivity. Although the feasibility of the effect is shown in multiple in vivo experiments, the stimulation mechanism remains open to discussion. Here we investigate in single-cell measurements the reaction of spiral ganglion neurons and model cells to irradiation with a nanosecond-pulsed laser beam over a broad wavelength range from 420 nm up to 1950 nm using the patch clamp technique. Cell reactions were wavelength- and pulse-energy-dependent but too small to elicit action potentials in the investigated spiral ganglion neurons. As the applied radiant exposure was much higher than the reported threshold for in vivo experiments in the same laser regime, we conclude that in a stimulation paradigm with nanosecond-pulses, direct neuronal stimulation is not the main cause of optical cochlea stimulation.
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Kranz K, Warnecke A, Lenarz T, Durisin M, Scheper V. Phosphodiesterase type 4 inhibitor rolipram improves survival of spiral ganglion neurons in vitro. PLoS One 2014; 9:e92157. [PMID: 24642701 PMCID: PMC3958480 DOI: 10.1371/journal.pone.0092157] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Accepted: 02/17/2014] [Indexed: 12/11/2022] Open
Abstract
Sensorineural deafness is caused by damage of hair cells followed by degeneration of the spiral ganglion neurons and can be moderated by cochlear implants. However, the benefit of the cochlear implant depends on the excitability of the spiral ganglion neurons. Therefore, current research focuses on the identification of agents that will preserve their degeneration. In this project we investigated the neuroprotective effect of Rolipram as a promising agent to improve the viability of the auditory neurons. It is a pharmaceutical agent that acts by selective inhibition of the phosphodiesterase 4 leading to an increase in cyclic AMP. Different studies reported a neuroprotective effect of Rolipram. However, its significance for the survival of SGN has not been reported so far. Thus, we isolated spiral ganglion cells of neonatal rats for cultivation with different Rolipram concentrations and determined the neuronal survival rate. Furthermore, we examined immunocytologically distinct proteins that might be involved in the neuroprotective signalling pathway of Rolipram and determined endogenous BDNF by ELISA. When applied at a concentration of 0.1 nM, Rolipram improved the survival of SGN in vitro. According to previous studies, our immunocytological data showed that Rolipram application induces the phosphorylation and thereby activation of the transcription factor CREB. This activation can be mediated by the cAMP-PKA-signalling pathway as well as via ERK as a part of the MAP-kinase pathway. However, only in cultures pre-treated with BDNF, an endogenous increase of BDNF was detected. We conclude that Rolipram has the potential to improve the vitality of neonatal auditory nerve cells in vitro. Further investigations are necessary to prove the effect of Rolipram in vivo in the adult organism after lesion of the hair cells and insertion of cochlear implants.
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Affiliation(s)
- Katharina Kranz
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Athanasia Warnecke
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Thomas Lenarz
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Martin Durisin
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Verena Scheper
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
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TrkB-mediated protection against circadian sensitivity to noise trauma in the murine cochlea. Curr Biol 2014; 24:658-63. [PMID: 24583017 DOI: 10.1016/j.cub.2014.01.047] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 12/20/2013] [Accepted: 01/21/2014] [Indexed: 12/17/2022]
Abstract
Noise-induced hearing loss (NIHL) is a debilitating sensory impairment affecting 10%-15% of the population, caused primarily through damage to the sensory hair cells or to the auditory neurons. Once lost, these never regenerate [1], and no effective drugs are available [2, 3]. Emerging evidence points toward an important contribution of synaptic ribbons in the long-term coupling of the inner hair cell and afferent neuron synapse to maintain hearing [4]. Here we show in nocturnal mice that night noise overexposure triggers permanent hearing loss, whereas mice overexposed during the day recover to normal auditory thresholds. In view of this time-dependent sensitivity, we identified a self-sustained circadian rhythm in the isolated cochlea, as evidenced by circadian expression of clock genes and ample PERIOD2::LUCIFERASE oscillations, originating mainly from the primary auditory neurons and hair cells. The transcripts of the otoprotecting brain-derived neurotrophic factor (BDNF) showed higher levels in response to day noise versus night noise, suggesting that BDNF-mediated signaling regulates noise sensitivity throughout the day. Administration of a selective BDNF receptor, tropomyosin-related kinase type B (TrkB), in the night protected the inner hair cell's synaptic ribbons and subsequent full recovery of hearing thresholds after night noise overexposure. The TrkB agonist shifted the phase and boosted the amplitude of circadian rhythms in the isolated cochlea. These findings highlight the coupling of circadian rhythmicity and the TrkB receptor for the successful prevention and treatment of NIHL.
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Needham K, Hyakumura T, Gunewardene N, Dottori M, Nayagam BA. Electrophysiological properties of neurosensory progenitors derived from human embryonic stem cells. Stem Cell Res 2013; 12:241-9. [PMID: 24280418 DOI: 10.1016/j.scr.2013.10.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 10/30/2013] [Accepted: 10/30/2013] [Indexed: 01/19/2023] Open
Abstract
In severe cases of sensorineural hearing loss where the numbers of auditory neurons are significantly depleted, stem cell-derived neurons may provide a potential source of replacement cells. The success of such a therapy relies upon producing a population of functional neurons from stem cells, to enable precise encoding of sound information to the brainstem. Using our established differentiation assay to produce sensory neurons from human stem cells, patch-clamp recordings indicated that all neurons examined generated action potentials and displayed both transient sodium and sustained potassium currents. Stem cell-derived neurons reliably entrained to stimuli up to 20 pulses per second (pps), with 50% entrainment at 50 pps. A comparison with cultured primary auditory neurons indicated similar firing precision during low-frequency stimuli, but significant differences after 50 pps due to differences in action potential latency and width. The firing properties of stem cell-derived neurons were also considered relative to time in culture (31-56 days) and revealed no change in resting membrane potential, threshold or firing latency over time. Thus, while stem cell-derived neurons did not entrain to high frequency stimulation as effectively as mammalian auditory neurons, their electrical phenotype was stable in culture and consistent with that reported for embryonic auditory neurons.
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Affiliation(s)
- Karina Needham
- Department of Otolaryngology, University of Melbourne, Royal Victorian Eye and Ear Hospital, Level 2, 32 Gisborne Street, East Melbourne, VIC 3002, Australia; Department of Medicine, St Vincent's Hospital, University of Melbourne, Level 4, Clinical Sciences Building, 29 Regent Street, Fitzroy, VIC 3065, Australia.
| | - Tomoko Hyakumura
- Department of Otolaryngology, University of Melbourne, Royal Victorian Eye and Ear Hospital, Level 2, 32 Gisborne Street, East Melbourne, VIC 3002, Australia.
| | - Niliksha Gunewardene
- Department of Otolaryngology, University of Melbourne, Royal Victorian Eye and Ear Hospital, Level 2, 32 Gisborne Street, East Melbourne, VIC 3002, Australia.
| | - Mirella Dottori
- Centre for Neural Engineering, NICTA, University of Melbourne, 203 Bouverie Street, Parkville, VIC 3010, Australia.
| | - Bryony A Nayagam
- Department of Otolaryngology, University of Melbourne, Royal Victorian Eye and Ear Hospital, Level 2, 32 Gisborne Street, East Melbourne, VIC 3002, Australia; Department of Audiology and Speech Pathology, University of Melbourne, 550 Swanston Street, Parkville, VIC 3010, Australia; Bionics Institute, 384-388 Albert Street, East Melbourne, VIC 3002, Australia.
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Kaiser O, Paasche G, Stöver T, Ernst S, Lenarz T, Kral A, Warnecke A. TGF-beta superfamily member activin A acts with BDNF and erythropoietin to improve survival of spiral ganglion neurons in vitro. Neuropharmacology 2013; 75:416-25. [PMID: 23973291 DOI: 10.1016/j.neuropharm.2013.08.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 07/03/2013] [Accepted: 08/08/2013] [Indexed: 01/15/2023]
Abstract
Activins are regulators of embryogenesis, osteogenesis, hormones and neuronal survival. Even though activin receptor type II has been detected in spiral ganglion neurons (SGN), little is known about the role of activins in the inner ear. An activin-mediated neuroprotection is of considerable clinical interest since SGN are targets of electrical stimulation with cochlear implants in hearing impaired patients. Thus, the presence of activin type-I and type-II receptors was demonstrated immunocytochemically and the individual and combined effects of activin A, erythropoietin (EPO) and brain-derived neurotrophic factor (BDNF) on SGN were examined in vitro. SGN isolated from neonatal rats (P 3-5) were cultured in serum-free medium supplemented with activin A, BDNF and EPO. Compared to the negative control, survival rates of SGN were significantly improved when cultivated individually with activin A (p<0.001) and in combination with BDNF (p<0.001). Neither neurite outgrowth nor neuronal survival was influenced by the addition of EPO to activin A-treated neurons. However, when all three factors were added, a significantly (p<0.001) improved neuronal survival was observed (61.2±3.6%) compared to activin A (25.4±2.1%), BDNF (22.8±3.3%) and BDNF+EPO (19.2±1.5%). Under the influence of the EPO-inhibitors, this increase in neuronal survival was blocked. Acting with BDNF and EPO to promote neuronal survival in vitro, activin A presents an interesting factor for pharmacological intervention in the inner ear. The present study demonstrates a synergetic effect of a combined therapy with several trophic factors.
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Affiliation(s)
- Odett Kaiser
- Department of Otolaryngology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany.
| | - Gerrit Paasche
- Department of Otolaryngology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Timo Stöver
- Department of Otolaryngology, University Hospital, Johann Wolfgang Goethe University, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany
| | - Stefanie Ernst
- Institute for Biometry, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Thomas Lenarz
- Department of Otolaryngology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Andrej Kral
- Department of Otolaryngology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Athanasia Warnecke
- Department of Otolaryngology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany.
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Kopelovich JC, Cagaanan AP, Miller CA, Abbas PJ, Green SH. Intracochlear electrical stimulation suppresses apoptotic signaling in rat spiral ganglion neurons after deafening in vivo. Otolaryngol Head Neck Surg 2013; 149:745-52. [PMID: 23907267 DOI: 10.1177/0194599813498702] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
OBJECTIVE To establish the intracellular consequences of electrical stimulation to spiral ganglion neurons after deafferentation. Here we use a rat model to determine the effect of both low and high pulse rate acute electrical stimulation on activation of the proapoptotic transcription factor Jun in deafferented spiral ganglion neurons in vivo. STUDY DESIGN Experimental animal study. SETTING Hearing research laboratories of the University of Iowa Departments of Biology and Otolaryngology. METHODS A single electrode was implanted through the round window of kanamycin-deafened rats at either postnatal day 32 (P32, n = 24) or P60 (n = 22) for 4 hours of stimulation (monopolar, biphasic pulses, amplitude twice electrically evoked auditory brainstem response [eABR] threshold) at either 100 or 5000 Hz. Jun phosphorylation was assayed by immunofluorescence to quantitatively assess the effect of electrical stimulation on proapoptotic signaling. RESULTS Jun phosphorylation was reliably suppressed by 100 Hz stimuli in deafened cochleae of P32 but not P60 rats. This effect was not significant in the basal cochlear turns. Stimulation frequency may be consequential: 100 Hz was significantly more effective than was 5 kHz stimulation in suppressing phospho-Jun. CONCLUSIONS Suppression of Jun phosphorylation occurs in deafferented spiral ganglion neurons after only 4 hours of electrical stimulation. This finding is consistent with the hypothesis that electrical stimulation can decrease spiral ganglion neuron death after deafferentation.
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Affiliation(s)
- Jonathan C Kopelovich
- Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, Iowa, USA
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Grumbles RM, Liu Y, Thomas CM, Wood PM, Thomas CK. Acute stimulation of transplanted neurons improves motoneuron survival, axon growth, and muscle reinnervation. J Neurotrauma 2013; 30:1062-9. [PMID: 23544978 PMCID: PMC3689928 DOI: 10.1089/neu.2012.2797] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Few options exist for treatment of pervasive motoneuron death after spinal cord injury or in neurodegenerative diseases such as amyotrophic lateral sclerosis. Local transplantation of embryonic motoneurons into an axotomized peripheral nerve is a promising approach to arrest the atrophy of denervated muscles; however, muscle reinnervation is limited by poor motoneuron survival. The aim of the present study was to test whether acute electrical stimulation of transplanted embryonic neurons promotes motoneuron survival, axon growth, and muscle reinnervation. The sciatic nerve of adult Fischer rats was transected to mimic the widespread denervation seen after disease or injury. Acutely dissociated rat embryonic ventral spinal cord cells were transplanted into the distal tibial nerve stump as a neuron source for muscle reinnervation. Immediately post-transplantation, the cells were stimulated at 20 Hz for 1 h. Other groups were used to control for the cell transplantation and stimulation. When neurons were stimulated acutely, there were significantly more neurons, including cholinergic neurons, 10 weeks after transplantation. This led to enhanced numbers of myelinated axons, reinnervation of more muscle fibers, and more medial and lateral gastrocnemius muscles were functionally connected to the transplant. Reinnervation reduced muscle atrophy significantly. These data support the concept that electrical stimulation rescues transplanted motoneurons and facilitates muscle reinnervation.
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Affiliation(s)
- Robert M. Grumbles
- The Miami Project to Cure Paralysis, Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, Florida
| | - Yang Liu
- The Miami Project to Cure Paralysis, Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, Florida
| | - Christie M. Thomas
- The Miami Project to Cure Paralysis, Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, Florida
| | - Patrick M. Wood
- The Miami Project to Cure Paralysis, Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, Florida
| | - Christine K. Thomas
- The Miami Project to Cure Paralysis, Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, Florida
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, Florida
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46
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Regenerated synapses between postnatal hair cells and auditory neurons. J Assoc Res Otolaryngol 2013; 14:321-9. [PMID: 23423560 DOI: 10.1007/s10162-013-0374-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2012] [Accepted: 01/29/2013] [Indexed: 02/06/2023] Open
Abstract
Regeneration of synaptic connections between hair cells and spiral ganglion neurons would be required to restore hearing after neural loss. Here we demonstrate by immunohistochemistry the appearance of afferent-like cochlear synapses in vitro after co-culture of de-afferented organ of Corti with spiral ganglion neurons from newborn mice. The glutamatergic synaptic complexes at the ribbon synapse of the inner hair cell contain markers for presynaptic ribbons and postsynaptic densities. We found postsynaptic density protein PSD-95 at the contacts between hair cells and spiral ganglion neurons in newly formed synapses in vitro. The postsynaptic proteins were directly facing the CtBP2-positive presynaptic ribbons of the hair cells. BDNF and NT-3 promoted afferent synaptogenesis in vitro. Direct juxtaposition of the postsynaptic densities with the components of the preexisting ribbon synapse indicated that growing fibers recognized components of the presynaptic sites. Initiation of cochlear synaptogenesis appeared to be influenced by glutamate release from the hair cell ribbons at the presynaptic site since the synaptic regeneration was impaired in glutamate vesicular transporter 3 mutant mice. These insights into cochlear synaptogenesis could be relevant to regenerative approaches for neural loss in the cochlea.
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47
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Kondo K, Pak K, Chavez E, Mullen L, Euteneuer S, Ryan AF. Changes in responsiveness of rat spiral ganglion neurons to neurotrophins across age: differential regulation of survival and neuritogenesis. Int J Neurosci 2013; 123:465-75. [PMID: 23301942 DOI: 10.3109/00207454.2013.764497] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Developmental changes in responsiveness of rat spiral ganglion neurons (SGNs) to neurotrophin-3 (NT-3) and brain-derived neurotrophic factor (BDNF) were examined using an explant culture system. Spiral ganglion (SG) explants at embryonic Day 18 (E18), postnatal Day 0 (P0), P5, P10 and P20 were cultured with the addition of either NT-3 or BDNF at various concentrations (0.1-100 ng/ml) and analyzed the dose-response characteristics of three parameters: SGN survival, the number of neurites emanating from the explants and the length of neurite extension. In E18 cultures, SGN survival and neurite number were enhanced more strongly by NT-3 than by the BDNF. As the explants became more mature, the effects of NT-3 decreased, whereas those of BDNF increased, peaking at P0. Although the intrinsic capacity of SGNs to produce and extend neurites declined considerably by P20, they still retained the capacity to respond to both NT-3 and BDNF. These temporal patterns in responsiveness of SGNs to neurotrophins correspond well to the expression pattern of the two neurotrophins in cochlear sensory epithelium in vivo and also correlate with the time course of developmental events in SGNs such as cell death and the establishment of mature hair cell innervation patterns.
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Affiliation(s)
- Kenji Kondo
- Division of Otolaryngology and Neurosciences, Department of Surgery and Veterans Administration Medical Center, University of California, San Diego School of Medicine, La Jolla, CA 92093, USA
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Leake PA, Stakhovskaya O, Hetherington A, Rebscher SJ, Bonham B. Effects of brain-derived neurotrophic factor (BDNF) and electrical stimulation on survival and function of cochlear spiral ganglion neurons in deafened, developing cats. J Assoc Res Otolaryngol 2013; 14:187-211. [PMID: 23392612 DOI: 10.1007/s10162-013-0372-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Accepted: 01/03/2013] [Indexed: 12/26/2022] Open
Abstract
Both neurotrophic support and neural activity are required for normal postnatal development and survival of cochlear spiral ganglion (SG) neurons. Previous studies in neonatally deafened cats demonstrated that electrical stimulation (ES) from a cochlear implant can promote improved SG survival but does not completely prevent progressive neural degeneration. Neurotrophic agents combined with an implant may further improve neural survival. Short-term studies in rodents have shown that brain-derived neurotrophic factor (BDNF) promotes SG survival after deafness and may be additive to trophic effects of stimulation. Our recent study in neonatally deafened cats provided the first evidence of BDNF neurotrophic effects in the developing auditory system over a prolonged duration Leake et al. (J Comp Neurol 519:1526-1545, 2011). Ten weeks of intracochlear BDNF infusion starting at 4 weeks of age elicited significant improvement in SG survival and larger soma size compared to contralateral. In the present study, the same deafening and BDNF infusion procedures were combined with several months of ES from an implant. After combined BDNF + ES, a highly significant increase in SG numerical density (>50 % improvement re: contralateral) was observed, which was significantly greater than the neurotrophic effect seen with ES-only over comparable durations. Combined BDNF + ES also resulted in a higher density of myelinated radial nerve fibers within the osseous spiral lamina. However, substantial ectopic and disorganized sprouting of these fibers into the scala tympani also occurred, which may be deleterious to implant function. EABR thresholds improved (re: initial thresholds at time of implantation) on the chronically stimulated channels of the implant. Terminal electrophysiological studies recording in the inferior colliculus (IC) revealed that the basic cochleotopic organization was intact in the midbrain in all studied groups. In deafened controls or after ES-only, lower IC thresholds were correlated with more selective activation widths as expected, but no such correlation was seen after BDNF + ES due to much greater variability in both measures.
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Affiliation(s)
- Patricia A Leake
- Epstein Hearing Research Laboratory, Department of Otolaryngology-Head and Neck Surgery, University of California San Francisco, 533 Parnassus Ave., San Francisco, CA 94143-0526, USA.
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Needham K, Minter RL, Shepherd RK, Nayagam BA. Challenges for stem cells to functionally repair the damaged auditory nerve. Expert Opin Biol Ther 2013; 13:85-101. [PMID: 23094991 PMCID: PMC3543850 DOI: 10.1517/14712598.2013.728583] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
INTRODUCTION In the auditory system, a specialized subset of sensory neurons are responsible for correctly relaying precise pitch and temporal cues to the brain. In individuals with severe-to-profound sensorineural hearing impairment these sensory auditory neurons can be directly stimulated by a cochlear implant, which restores sound input to the brainstem after the loss of hair cells. This neural prosthesis therefore depends on a residual population of functional neurons in order to function effectively. AREAS COVERED In severe cases of sensorineural hearing loss where the numbers of auditory neurons are significantly depleted, the benefits derived from a cochlear implant may be minimal. One way in which to restore function to the auditory nerve is to replace these lost neurons using differentiated stem cells, thus re-establishing the neural circuit required for cochlear implant function. Such a therapy relies on producing an appropriate population of electrophysiologically functional neurons from stem cells, and on these cells integrating and reconnecting in an appropriate manner in the deaf cochlea. EXPERT OPINION Here we review progress in the field to date, including some of the key functional features that stem cell-derived neurons would need to possess and how these might be enhanced using electrical stimulation from a cochlear implant.
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Affiliation(s)
- Karina Needham
- University of Melbourne, Department of Otolaryngology, East Melbourne, Australia.
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Kouzoukas DE, Li G, Takapoo M, Moninger T, Bhalla RC, Pantazis NJ. Intracellular calcium plays a critical role in the alcohol-mediated death of cerebellar granule neurons. J Neurochem 2012; 124:323-35. [PMID: 23121601 DOI: 10.1111/jnc.12076] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Revised: 09/30/2012] [Accepted: 10/10/2012] [Indexed: 11/28/2022]
Abstract
Alcohol is a potent neuroteratogen that can trigger neuronal death in the developing brain. However, the mechanism underlying this alcohol-induced neuronal death is not fully understood. Utilizing primary cultures of cerebellar granule neurons (CGN), we tested the hypothesis that the alcohol-induced increase in intracellular calcium [Ca(2+)](i) causes the death of CGN. Alcohol induced a dose-dependent (200-800 mg/dL) neuronal death within 24 h. Ratiometric Ca(2+) imaging with Fura-2 revealed that alcohol causes a rapid (1-2 min), dose-dependent increase in [Ca(2+)](i), which persisted for the duration of the experiment (5 or 7 min). The alcohol-induced increase in [Ca(2+)](i) was observed in Ca(2+) -free media, suggesting intracellular Ca(2+) release. Pre-treatment of CGN cultures with an inhibitor (2-APB) of the inositol-triphosphate receptor (IP(3) R), which regulates Ca(2+) release from the endoplasmic reticulum (ER), blocked both the alcohol-induced rise in [Ca(2+)](i) and the neuronal death caused by alcohol. Similarly, pre-treatment with BAPTA/AM, a Ca(2+) -chelator, also inhibited the alcohol-induced surge in [Ca(2+) ](i) and prevented neuronal death. In conclusion, alcohol disrupts [Ca(2+)](i) homeostasis in CGN by releasing Ca(2+) from intracellular stores, resulting in a sustained increase in [Ca(2+)](i). This sustained increase in [Ca(2+)](i) may be a key determinant in the mechanism underlying alcohol-induced neuronal death.
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Affiliation(s)
- Dimitrios E Kouzoukas
- Department of Anatomy and Cell Biology, Carver College of Medicine, The University of Iowa, Iowa City, IA, USA
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