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Vecchi JT, Claussen AD, Hansen MR. Decreasing the physical gap in the neural-electrode interface and related concepts to improve cochlear implant performance. Front Neurosci 2024; 18:1425226. [PMID: 39114486 PMCID: PMC11303154 DOI: 10.3389/fnins.2024.1425226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Accepted: 07/11/2024] [Indexed: 08/10/2024] Open
Abstract
Cochlear implants (CI) represent incredible devices that restore hearing perception for those with moderate to profound sensorineural hearing loss. However, the ability of a CI to restore complex auditory function is limited by the number of perceptually independent spectral channels provided. A major contributor to this limitation is the physical gap between the CI electrodes and the target spiral ganglion neurons (SGNs). In order for CI electrodes to stimulate SGNs more precisely, and thus better approximate natural hearing, new methodologies need to be developed to decrease this gap, (i.e., transitioning CIs from a far-field to near-field device). In this review, strategies aimed at improving the neural-electrode interface are discussed in terms of the magnitude of impact they could have and the work needed to implement them. Ongoing research suggests current clinical efforts to limit the CI-related immune response holds great potential for improving device performance. This could eradicate the dense, fibrous capsule surrounding the electrode and enhance preservation of natural cochlear architecture, including SGNs. In the long term, however, optimized future devices will likely need to induce and guide the outgrowth of the peripheral process of SGNs to be in closer proximity to the CI electrode in order to better approximate natural hearing. This research is in its infancy; it remains to be seen which strategies (surface patterning, small molecule release, hydrogel coating, etc.) will be enable this approach. Additionally, these efforts aimed at optimizing CI function will likely translate to other neural prostheses, which face similar issues.
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Affiliation(s)
- Joseph T. Vecchi
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, Iowa City, IA, United States
- Department of Otolaryngology Head-Neck Surgery, Carver College of Medicine, Iowa City, IA, United States
| | - Alexander D. Claussen
- Department of Otolaryngology Head-Neck Surgery, Carver College of Medicine, Iowa City, IA, United States
| | - Marlan R. Hansen
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, Iowa City, IA, United States
- Department of Otolaryngology Head-Neck Surgery, Carver College of Medicine, 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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Rapti G. Regulation of axon pathfinding by astroglia across genetic model organisms. Front Cell Neurosci 2023; 17:1241957. [PMID: 37941606 PMCID: PMC10628440 DOI: 10.3389/fncel.2023.1241957] [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: 06/18/2023] [Accepted: 09/07/2023] [Indexed: 11/10/2023] Open
Abstract
Glia and neurons are intimately associated throughout bilaterian nervous systems, and were early proposed to interact for patterning circuit assembly. The investigations of circuit formation progressed from early hypotheses of intermediate guideposts and a "glia blueprint", to recent genetic and cell manipulations, and visualizations in vivo. An array of molecular factors are implicated in axon pathfinding but their number appears small relatively to circuit complexity. Comprehending this circuit complexity requires to identify unknown factors and dissect molecular topographies. Glia contribute to both aspects and certain studies provide molecular and functional insights into these contributions. Here, I survey glial roles in guiding axon navigation in vivo, emphasizing analogies, differences and open questions across major genetic models. I highlight studies pioneering the topic, and dissect recent findings that further advance our current molecular understanding. Circuits of the vertebrate forebrain, visual system and neural tube in zebrafish, mouse and chick, the Drosophila ventral cord and the C. elegans brain-like neuropil emerge as major contexts to study glial cell functions in axon navigation. I present astroglial cell types in these models, and their molecular and cellular interactions that drive axon guidance. I underline shared principles across models, conceptual or technical complications, and open questions that await investigation. Glia of the radial-astrocyte lineage, emerge as regulators of axon pathfinding, often employing common molecular factors across models. Yet this survey also highlights different involvements of glia in embryonic navigation or pioneer axon pathfinding, and unknowns in the molecular underpinnings of glial cell functions. Future cellular and molecular investigations should complete the comprehensive view of glial roles in circuit assembly.
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Affiliation(s)
- Georgia Rapti
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
- Epigenetics and Neurobiology Unit, European Molecular Biology Laboratory, Rome, Italy
- Interdisciplinary Center of Neurosciences, Heidelberg University, Heidelberg, Germany
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4
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Laureano A, Kim J, Martinez E, Kwan KY. Chromodomain helicase DNA binding protein 4 in cell fate decisions. Hear Res 2023; 436:108813. [PMID: 37329862 PMCID: PMC10463912 DOI: 10.1016/j.heares.2023.108813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 05/09/2023] [Accepted: 05/24/2023] [Indexed: 06/19/2023]
Abstract
Loss of spiral ganglion neurons (SGNs) in the cochlea causes hearing loss. Understanding the mechanisms of cell fate transition accelerates efforts that employ directed differentiation and lineage conversion to repopulate lost SGNs. Proposed strategies to regenerate SGNs rely on altering cell fate by activating transcriptional regulatory networks, but repressing networks for alternative cell lineages is also essential. Epigenomic changes during cell fate transitions suggest that CHD4 represses gene expression by altering the chromatin status. Despite limited direct investigations, human genetic studies implicate CHD4 function in the inner ear. The possibility of CHD4 in suppressing alternative cell fates to promote inner ear regeneration is discussed.
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Affiliation(s)
- Alejandra Laureano
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Jihyun Kim
- Department of Cell Biology & Neuroscience, Rutgers University, Nelson Labs D250 604 Allison Rd., Piscataway, NJ 08854, USA; Stem Cell Research Center and Keck Center for Collaborative Neuroscience, Rutgers University, Piscataway, NJ 08854, USA
| | - Edward Martinez
- Department of Cell Biology & Neuroscience, Rutgers University, Nelson Labs D250 604 Allison Rd., Piscataway, NJ 08854, USA; Stem Cell Research Center and Keck Center for Collaborative Neuroscience, Rutgers University, Piscataway, NJ 08854, USA
| | - Kelvin Y Kwan
- Department of Cell Biology & Neuroscience, Rutgers University, Nelson Labs D250 604 Allison Rd., Piscataway, NJ 08854, USA; Stem Cell Research Center and Keck Center for Collaborative Neuroscience, Rutgers University, Piscataway, NJ 08854, USA.
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5
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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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Li L, Yu K, Mo Z, Yang K, Chen F, Yang J. In Vitro Neurotrophic Properties and Structural Characterization of a New Polysaccharide LTC-1 from Pyrola corbieri Levl (Luticao). Molecules 2023; 28:1544. [PMID: 36838533 PMCID: PMC9964326 DOI: 10.3390/molecules28041544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 02/02/2023] [Accepted: 02/03/2023] [Indexed: 02/09/2023] Open
Abstract
Pyrola corbieri Levl has been used to strengthen bones and nourish the kidney (the kidney governs the bone and is beneficial to the brain) by the local Miao people in China. However, the functional components and neurotrophic activity have not been reported. A new acidic homogeneous heteropolysaccharide named LTC-1 was obtained and characterized by periodate oxidation, Smith degradation, partial acid hydrolysis, GC-MS spectrometry, methylation analysis, and Fourier transform infrared spectroscopy, and its molecular weight was 3239 Da. The content of mannuronic acid (Man A) in LTC-1 was 46%, and the neutral sugar was composed of L-rhamnose (L-Rha), L-arabinose (L-Ara), D-xylose (D-Xyl), D-mannose (D-Man), D-glucose (D-Glc) and D-galactose (D-Gal) with a molar ratio of 1.00:3.63:0.86:1.30:6.97:1.30. The main chain of LTC-1 was composed of Glc, Gal, Man, Man A and the branched chain Ara, Glc, Gal. The terminal residues were composed of Glc and Gal. The main chain and branched chains were linked by (1→5)-linked-Ara, (1→3)-linked-Glc, (1→4)-linked-Glc, (1→6)-linked-Glc, (1→3)-linked-Gal, (1→6)-linked-Gal, (1→3, 6)-linked-Man and ManA. Meanwhile, neurotrophic activity was evaluated through PC12 and primary hippocampal neuronal cell models. LTC-1 exhibited neurotrophic activity in a concentration-dependent manner, which significantly induced the differentiation of PC12 cells, promoted the neurite outgrowth of PC12 cells, enhanced the formation of the web architecture of dendrites, and increased the density of dendritic spines in hippocampal neurons and the expression of PSD-95. These results displayed significant neurotrophic factor-like activity of LTC-1, which suggests that LTC-1 is a potential treatment option for neurodegenerative diseases.
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Affiliation(s)
- Liangqun Li
- State Key Laboratory for Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang 550014, China
- The Key Laboratory of Chemistry for Natural Products of Guizhou Province and Chinese Academy of Sciences, Guiyang 550014, China
| | - Kangkang Yu
- School of Life Science, Shanghai University, Shanghai 200444, China
| | | | - Keling Yang
- State Key Laboratory for Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang 550014, China
- The Key Laboratory of Chemistry for Natural Products of Guizhou Province and Chinese Academy of Sciences, Guiyang 550014, China
| | - Fuxue Chen
- School of Life Science, Shanghai University, Shanghai 200444, China
| | - Juan Yang
- State Key Laboratory for Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang 550014, China
- The Key Laboratory of Chemistry for Natural Products of Guizhou Province and Chinese Academy of Sciences, Guiyang 550014, China
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7
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Vogl C, Neef J, Wichmann C. Methods for multiscale structural and functional analysis of the mammalian cochlea. Mol Cell Neurosci 2022; 120:103720. [DOI: 10.1016/j.mcn.2022.103720] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 02/13/2022] [Accepted: 03/08/2022] [Indexed: 01/11/2023] Open
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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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Motz CT, Kabat V, Saxena T, Bellamkonda RV, Zhu C. Neuromechanobiology: An Expanding Field Driven by the Force of Greater Focus. Adv Healthc Mater 2021; 10:e2100102. [PMID: 34342167 PMCID: PMC8497434 DOI: 10.1002/adhm.202100102] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 07/06/2021] [Indexed: 12/14/2022]
Abstract
The brain processes information by transmitting signals through highly connected and dynamic networks of neurons. Neurons use specific cellular structures, including axons, dendrites and synapses, and specific molecules, including cell adhesion molecules, ion channels and chemical receptors to form, maintain and communicate among cells in the networks. These cellular and molecular processes take place in environments rich of mechanical cues, thus offering ample opportunities for mechanical regulation of neural development and function. Recent studies have suggested the importance of mechanical cues and their potential regulatory roles in the development and maintenance of these neuronal structures. Also suggested are the importance of mechanical cues and their potential regulatory roles in the interaction and function of molecules mediating the interneuronal communications. In this review, the current understanding is integrated and promising future directions of neuromechanobiology are suggested at the cellular and molecular levels. Several neuronal processes where mechanics likely plays a role are examined and how forces affect ligand binding, conformational change, and signal induction of molecules key to these neuronal processes are indicated, especially at the synapse. The disease relevance of neuromechanobiology as well as therapies and engineering solutions to neurological disorders stemmed from this emergent field of study are also discussed.
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Affiliation(s)
- Cara T Motz
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332-0363, USA
- Parker H. Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, GA, 30332-0363, USA
| | - Victoria Kabat
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332-0363, USA
| | - Tarun Saxena
- Department of Biomedical Engineering, Duke University, Durham, NC, 27709, USA
| | - Ravi V Bellamkonda
- Department of Biomedical Engineering, Pratt School of Engineering, Duke University, Durham, NC, 27708, USA
| | - Cheng Zhu
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332-0363, USA
- Parker H. Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, GA, 30332-0363, USA
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332-0363, USA
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10
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Tasdemir-Yilmaz OE, Druckenbrod NR, Olukoya OO, Dong W, Yung AR, Bastille I, Pazyra-Murphy MF, Sitko AA, Hale EB, Vigneau S, Gimelbrant AA, Kharchenko PV, Goodrich LV, Segal RA. Diversity of developing peripheral glia revealed by single-cell RNA sequencing. Dev Cell 2021; 56:2516-2535.e8. [PMID: 34469751 DOI: 10.1016/j.devcel.2021.08.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 05/31/2021] [Accepted: 08/06/2021] [Indexed: 12/22/2022]
Abstract
The peripheral nervous system responds to a wide variety of sensory stimuli, a process that requires great neuronal diversity. These diverse neurons are closely associated with glial cells originating from the neural crest. However, the molecular nature and diversity among peripheral glia are not understood. Here, we used single-cell RNA sequencing to profile developing and mature glia from somatosensory dorsal root ganglia and auditory spiral ganglia. We found that glial precursors (GPs) in these two systems differ in their transcriptional profiles. Despite their unique features, somatosensory and auditory GPs undergo convergent differentiation to generate molecularly uniform myelinating and non-myelinating Schwann cells. By contrast, somatosensory and auditory satellite glial cells retain system-specific features. Lastly, we identified a glial signature gene set, providing new insights into commonalities among glia across the nervous system. This survey of gene expression in peripheral glia constitutes a resource for understanding functions of glia across different sensory modalities.
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Affiliation(s)
- Ozge E Tasdemir-Yilmaz
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Noah R Druckenbrod
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | | | - Weixiu Dong
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA 02115, USA
| | - Andrea R Yung
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Isle Bastille
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Maria F Pazyra-Murphy
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Austen A Sitko
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Evan B Hale
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Sébastien Vigneau
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | | | - Peter V Kharchenko
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA 02115, USA
| | - Lisa V Goodrich
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
| | - Rosalind A Segal
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
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11
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Interaction of micropatterned topographical and biochemical cues to direct neurite growth from spiral ganglion neurons. Hear Res 2021; 409:108315. [PMID: 34343850 DOI: 10.1016/j.heares.2021.108315] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 05/07/2021] [Accepted: 07/12/2021] [Indexed: 01/01/2023]
Abstract
Functional outcomes with neural prosthetic devices, such as cochlear implants, are limited in part due to physical separation between the stimulating elements and the neurons they stimulate. One strategy to close this gap aims to precisely guide neurite regeneration to position the neurites in closer proximity to electrode arrays. Here, we explore the ability of micropatterned biochemical and topographic guidance cues, singly and in combination, to direct the growth of spiral ganglion neuron (SGN) neurites, the neurons targeted by cochlear implants. Photopolymerization of methacrylate monomers was used to form unidirectional topographical features of ridges and grooves in addition to multidirectional patterns with 90o angle turns. Microcontact printing was also used to create similar uni- and multi-directional patterns of peptides on polymer surfaces. Biochemical cues included peptides that facilitate (laminin, LN) or repel (EphA4-Fc) neurite growth. On flat surfaces, SGN neurites preferentially grew on LN-coated stripes and avoided EphA4-Fc-coated stripes. LN or EphA4-Fc was selectively adsorbed onto the ridges or grooves to test the neurite response to a combination of topographical and biochemical cues. Coating the ridges with EphA4-Fc and grooves with LN lead to enhanced SGN alignment to topographical patterns. Conversely, EphA4-Fc coating on the grooves or LN coating on the ridges tended to disrupt alignment to topographical patterns. SGN neurites respond to combinations of topographical and biochemical cues and surface patterning that leverages both cues enhance guided neurite growth.
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12
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Elliott KL, Pavlínková G, Chizhikov VV, Yamoah EN, Fritzsch B. Development in the Mammalian Auditory System Depends on Transcription Factors. Int J Mol Sci 2021; 22:ijms22084189. [PMID: 33919542 PMCID: PMC8074135 DOI: 10.3390/ijms22084189] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Revised: 04/15/2021] [Accepted: 04/16/2021] [Indexed: 12/16/2022] Open
Abstract
We review the molecular basis of several transcription factors (Eya1, Sox2), including the three related genes coding basic helix–loop–helix (bHLH; see abbreviations) proteins (Neurog1, Neurod1, Atoh1) during the development of spiral ganglia, cochlear nuclei, and cochlear hair cells. Neuronal development requires Neurog1, followed by its downstream target Neurod1, to cross-regulate Atoh1 expression. In contrast, hair cells and cochlear nuclei critically depend on Atoh1 and require Neurod1 expression for interactions with Atoh1. Upregulation of Atoh1 following Neurod1 loss changes some vestibular neurons’ fate into “hair cells”, highlighting the significant interplay between the bHLH genes. Further work showed that replacing Atoh1 by Neurog1 rescues some hair cells from complete absence observed in Atoh1 null mutants, suggesting that bHLH genes can partially replace one another. The inhibition of Atoh1 by Neurod1 is essential for proper neuronal cell fate, and in the absence of Neurod1, Atoh1 is upregulated, resulting in the formation of “intraganglionic” HCs. Additional genes, such as Eya1/Six1, Sox2, Pax2, Gata3, Fgfr2b, Foxg1, and Lmx1a/b, play a role in the auditory system. Finally, both Lmx1a and Lmx1b genes are essential for the cochlear organ of Corti, spiral ganglion neuron, and cochlear nuclei formation. We integrate the mammalian auditory system development to provide comprehensive insights beyond the limited perception driven by singular investigations of cochlear neurons, cochlear hair cells, and cochlear nuclei. A detailed analysis of gene expression is needed to understand better how upstream regulators facilitate gene interactions and mammalian auditory system development.
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Affiliation(s)
- Karen L. Elliott
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA;
| | - Gabriela Pavlínková
- Institute of Biotechnology of the Czech Academy of Sciences, 25250 Vestec, Czechia;
| | - Victor V. Chizhikov
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN 38163, USA;
| | - Ebenezer N. Yamoah
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, NV 89557, USA;
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA;
- Correspondence:
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13
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Bozhko DV, Galumov GK, Polovian AI, Kolchanova SM, Myrov VO, Stelmakh VA, Schiöth HB. BCNNM: A Framework for in silico Neural Tissue Development Modeling. Front Comput Neurosci 2021; 14:588224. [PMID: 33551782 PMCID: PMC7855713 DOI: 10.3389/fncom.2020.588224] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 12/18/2020] [Indexed: 12/02/2022] Open
Abstract
Cerebral (“brain”) organoids are high-fidelity in vitro cellular models of the developing brain, which makes them one of the go-to methods to study isolated processes of tissue organization and its electrophysiological properties, allowing to collect invaluable data for in silico modeling neurodevelopmental processes. Complex computer models of biological systems supplement in vivo and in vitro experimentation and allow researchers to look at things that no laboratory study has access to, due to either technological or ethical limitations. In this paper, we present the Biological Cellular Neural Network Modeling (BCNNM) framework designed for building dynamic spatial models of neural tissue organization and basic stimulus dynamics. The BCNNM uses a convenient predicate description of sequences of biochemical reactions and can be used to run complex models of multi-layer neural network formation from a single initial stem cell. It involves processes such as proliferation of precursor cells and their differentiation into mature cell types, cell migration, axon and dendritic tree formation, axon pathfinding and synaptogenesis. The experiment described in this article demonstrates a creation of an in silico cerebral organoid-like structure, constituted of up to 1 million cells, which differentiate and self-organize into an interconnected system with four layers, where the spatial arrangement of layers and cells are consistent with the values of analogous parameters obtained from research on living tissues. Our in silico organoid contains axons and millions of synapses within and between the layers, and it comprises neurons with high density of connections (more than 10). In sum, the BCNNM is an easy-to-use and powerful framework for simulations of neural tissue development that provides a convenient way to design a variety of tractable in silico experiments.
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Affiliation(s)
- Dmitrii V Bozhko
- JetBrains Research Department, Space Office Center, Saint Petersburg, Russia
| | - Georgii K Galumov
- JetBrains Research Department, Space Office Center, Saint Petersburg, Russia
| | | | - Sofiia M Kolchanova
- JetBrains Research Department, Space Office Center, Saint Petersburg, Russia.,Department of Biology, University of Puerto Rico at Mayaguez, Mayaguez, PR, United States.,Theodosius Dobzhansky Center for Genome Bioinformatics, St. Petersburg State University, Saint Petersburg, Russia
| | - Vladislav O Myrov
- Neuroscience Center, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland.,Department of Neuroscience and Biomedical Engineering, Aalto University, Espoo, Finland
| | - Viktoriia A Stelmakh
- JetBrains Research Department, Space Office Center, Saint Petersburg, Russia.,Skolkovo Institute of Science and Technology, Center of Life Sciences, Moscow, Russia
| | - Helgi B Schiöth
- Department of Neuroscience, Functional Pharmacology, Uppsala University, Uppsala, Sweden.,Institute for Translational Medicine and Biotechnology, Sechenov First Moscow State Medical University, Moscow, Russia
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Özçete ÖD, Moser T. A sensory cell diversifies its output by varying Ca 2+ influx-release coupling among active zones. EMBO J 2020; 40:e106010. [PMID: 33346936 PMCID: PMC7917556 DOI: 10.15252/embj.2020106010] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 10/30/2020] [Accepted: 11/03/2020] [Indexed: 02/06/2023] Open
Abstract
The cochlea encodes sound pressures varying over six orders of magnitude by collective operation of functionally diverse spiral ganglion neurons (SGNs). The mechanisms enabling this functional diversity remain elusive. Here, we asked whether the sound intensity information, contained in the receptor potential of the presynaptic inner hair cell (IHC), is fractionated via heterogeneous synapses. We studied the transfer function of individual IHC synapses by combining patch‐clamp recordings with dual‐color Rhod‐FF and iGluSnFR imaging of presynaptic Ca2+ signals and glutamate release. Synapses differed in the voltage dependence of release: Those residing at the IHC' pillar side activated at more hyperpolarized potentials and typically showed tight control of release by few Ca2+ channels. We conclude that heterogeneity of voltage dependence and release site coupling of Ca2+ channels among the synapses varies synaptic transfer within individual IHCs and, thereby, likely contributes to the functional diversity of SGNs. The mechanism reported here might serve sensory cells and neurons more generally to diversify signaling even in close‐by synapses.
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Affiliation(s)
- Özge D Özçete
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Collaborative Research Center 889, University of Göttingen, Göttingen, Germany.,Auditory Neuroscience Group, Max Planck Institute of Experimental Medicine, Göttingen, Germany.,Göttingen Graduate Center for Neurosciences, Biophysics and Molecular Biosciences, University of Göttingen, Göttingen, Germany
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Collaborative Research Center 889, University of Göttingen, Göttingen, Germany.,Auditory Neuroscience Group, Max Planck Institute of Experimental Medicine, Göttingen, Germany.,Göttingen Graduate Center for Neurosciences, Biophysics and Molecular Biosciences, University of Göttingen, Göttingen, Germany.,Synaptic Nanophysiology Group, Max Planck Institute of Biophysical Chemistry, Göttingen, Germany.,Multiscale Bioimaging Cluster of Excellence (MBExC), University of Göttingen, Göttingen, Germany
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