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Vincent PFY, Young ED, Edge ASB, Glowatzki E. Auditory hair cells and spiral ganglion neurons regenerate synapses with refined release properties in vitro. Proc Natl Acad Sci U S A 2024; 121:e2315599121. [PMID: 39058581 PMCID: PMC11294990 DOI: 10.1073/pnas.2315599121] [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: 09/10/2023] [Accepted: 06/12/2024] [Indexed: 07/28/2024] Open
Abstract
Ribbon synapses between inner hair cells (IHCs) and type I spiral ganglion neurons (SGNs) in the inner ear are damaged by noise trauma and with aging, causing "synaptopathy" and hearing loss. Cocultures of neonatal denervated organs of Corti and newly introduced SGNs have been developed to find strategies for improving IHC synapse regeneration, but evidence of the physiological normality of regenerated synapses is missing. This study utilizes IHC optogenetic stimulation and SGN recordings, showing that, when P3-5 denervated organs of Corti are cocultured with SGNs, newly formed IHC/SGN synapses are indeed functional, exhibiting glutamatergic excitatory postsynaptic currents. When using older organs of Corti at P10-11, synaptic activity probed by deconvolution showed more mature release properties, closer to the specialized mode of IHC synaptic transmission crucial for coding the sound signal. This functional assessment of newly formed IHC synapses developed here, provides a powerful tool for testing approaches to improve synapse regeneration.
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Affiliation(s)
- Philippe F. Y. Vincent
- The Center for Hearing and Balance, The Johns Hopkins School of Medicine, Baltimore, MD21205
- Department of Otolaryngology Head and Neck Surgery, The Johns Hopkins School of Medicine, Baltimore, MD21205
| | - Eric D. Young
- The Center for Hearing and Balance, The Johns Hopkins School of Medicine, Baltimore, MD21205
- Department of Otolaryngology Head and Neck Surgery, The Johns Hopkins School of Medicine, Baltimore, MD21205
- Department of Neuroscience, The Johns Hopkins School of Medicine, Baltimore, MD21205
- Department of Biomedical Engineering, The Johns Hopkins School of Medicine, Baltimore, MD21205
| | - Albert S. B. Edge
- Department of Otolaryngology, Harvard Medical School, Boston, MA02115
- Eaton-Peabody Laboratory, Massachusetts Eye and Ear, Boston, MA02114
- Program in Speech and Hearing Bioscience and Technology, Harvard Medical School, Boston, MA02115
- Harvard Stem Cell Institute, Cambridge, MA02139
| | - Elisabeth Glowatzki
- The Center for Hearing and Balance, The Johns Hopkins School of Medicine, Baltimore, MD21205
- Department of Otolaryngology Head and Neck Surgery, The Johns Hopkins School of Medicine, Baltimore, MD21205
- Department of Neuroscience, The Johns Hopkins School of Medicine, Baltimore, MD21205
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Vincent PF, Young ED, Edge AS, Glowatzki E. Auditory Hair Cells and Spiral Ganglion Neurons Regenerate Synapses with Refined Release Properties In Vitro. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.05.561095. [PMID: 38076928 PMCID: PMC10705289 DOI: 10.1101/2023.10.05.561095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Ribbon synapses between inner hair cells (IHCs) and type I spiral ganglion neurons (SGNs) in the inner ear are damaged by noise trauma and with aging, causing 'synaptopathy 'and hearing loss. Co-cultures of neonatal denervated organs of Corti and newly introduced SGNs have been developed to find strategies for improving IHC synapse regeneration, but evidence of the physiological normality of regenerated synapses is missing. This study utilizes IHC optogenetic stimulation and SGN recordings, showing that newly formed IHC synapses are indeed functional, exhibiting glutamatergic excitatory postsynaptic currents. When older organs of Corti were plated, synaptic activity probed by deconvolution, showed more mature release properties, closer to the highly specialized mode of IHC synaptic transmission that is crucial for coding the sound signal. This newly developed functional assessment of regenerated IHC synapses provides a powerful tool for testing approaches to improve synapse regeneration.
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Affiliation(s)
- Philippe F.Y. Vincent
- The Center for Hearing and Balance, The Johns Hopkins School of Medicine, Baltimore, Maryland
- Department of Otolaryngology Head and Neck Surgery, The Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Eric D. Young
- The Center for Hearing and Balance, The Johns Hopkins School of Medicine, Baltimore, Maryland
- Department of Otolaryngology Head and Neck Surgery, The Johns Hopkins School of Medicine, Baltimore, Maryland
- Department of Neuroscience, The Johns Hopkins School of Medicine, Baltimore, Maryland
- Department of Biomedical Engineering, The Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Albert S.B. Edge
- Department of Otolaryngology, Harvard Medical School, Boston, Massachusetts, USA
- Eaton-Peabody Laboratory, Massachusetts Eye and Ear, Boston, Massachusetts, USA
- Program in Speech and Hearing Bioscience and Technology, Harvard Medical School, Boston, Massachusetts, USA
- Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
| | - Elisabeth Glowatzki
- The Center for Hearing and Balance, The Johns Hopkins School of Medicine, Baltimore, Maryland
- Department of Otolaryngology Head and Neck Surgery, The Johns Hopkins School of Medicine, Baltimore, Maryland
- Department of Neuroscience, The Johns Hopkins School of Medicine, Baltimore, Maryland
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Zhou L, Chen W, Jiang S, Xu R. In Vitro Models of Amyotrophic Lateral Sclerosis. Cell Mol Neurobiol 2023; 43:3783-3799. [PMID: 37870685 DOI: 10.1007/s10571-023-01423-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 10/04/2023] [Indexed: 10/24/2023]
Abstract
Amyotrophic Lateral Sclerosis (ALS) is one of the commonest neurodegenerative diseases of adult-onset, which is characterized by the progressive death of motor neurons in the cerebral cortex, brain stem and spinal cord. The dysfunction and death of motor neurons lead to the progressive muscle weakness, atrophy, fasciculations, spasticity and ultimately the whole paralysis of body. Despite the identification of several genetic mutations associated with the pathogenesis of ALS, including mutations in chromosome 9 open reading frame 72 leading to the abnormal expansion of GGGGCC repeat sequence, TAR DNA-binding protein 43, fused in sarcoma/translocated in liposarcoma, copper/zinc superoxide dismutase 1 (SOD1) and TANK-binding kinase 1, the exact mechanisms underlying the specific degeneration of motor neurons that causes ALS remain incompletely understood. At present, since the transgenic model expressed SOD1 mutants was established, multiple in vitro models of ALS have been developed for studying the pathology, pathophysiology and pathogenesis of ALS as well as searching the effective neurotherapeutics. This review reviewed the details of present established in vitro models used in studying the pathology, pathophysiology and pathogenesis of ALS. Meanwhile, we also discussed the advantages, disadvantages, cost and availability of each models.
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Affiliation(s)
- Lijun Zhou
- Department of Neurology, Jiangxi Provincial People's Hospital, Clinical College of Nanchang Medical College, First Affiliated Hospital of Nanchang Medical College, Xiangya Hospital of Central South University Jiangxi Hospital, National Regional Medical Center for Neurological Diseases, No. 266 Fenghe North Avenue, Honggutan District, Nanchang, 330008, Jiangxi, China
- Medical College of Nanchang University, Nanchang, 330006, China
| | - Wenzhi Chen
- Department of Neurology, Jiangxi Provincial People's Hospital, Clinical College of Nanchang Medical College, First Affiliated Hospital of Nanchang Medical College, Xiangya Hospital of Central South University Jiangxi Hospital, National Regional Medical Center for Neurological Diseases, No. 266 Fenghe North Avenue, Honggutan District, Nanchang, 330008, Jiangxi, China
| | - Shishi Jiang
- Department of Neurology, Jiangxi Provincial People's Hospital, Clinical College of Nanchang Medical College, First Affiliated Hospital of Nanchang Medical College, Xiangya Hospital of Central South University Jiangxi Hospital, National Regional Medical Center for Neurological Diseases, No. 266 Fenghe North Avenue, Honggutan District, Nanchang, 330008, Jiangxi, China
- Medical College of Nanchang University, Nanchang, 330006, China
| | - Renshi Xu
- Department of Neurology, Jiangxi Provincial People's Hospital, Clinical College of Nanchang Medical College, First Affiliated Hospital of Nanchang Medical College, Xiangya Hospital of Central South University Jiangxi Hospital, National Regional Medical Center for Neurological Diseases, No. 266 Fenghe North Avenue, Honggutan District, Nanchang, 330008, Jiangxi, China.
- Medical College of Nanchang University, Nanchang, 330006, China.
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3D culture of the spinal cord with roots as an ex vivo model for comparative studies of motor and sensory nerve regeneration. Exp Neurol 2023; 362:114322. [PMID: 36652972 DOI: 10.1016/j.expneurol.2023.114322] [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: 09/28/2022] [Revised: 12/21/2022] [Accepted: 01/13/2023] [Indexed: 01/18/2023]
Abstract
Motor and sensory nerves exhibit tissue-specific structural and functional features. However, in vitro models designed to reflect tissue-specific differences between motor and sensory nerve regeneration have rarely been reported. Here, by embedding the spinal cord with roots (SCWR) in a 3D hydrogel environment, we compared the nerve regeneration processes between the ventral and dorsal roots. The 3D hydrogel environment induced an outward migration of neurons in the gray matter of the spinal cord, which allowed the long-term survival of motor neurons. Tuj1 immunofluorescence labeling confirmed the regeneration of neurites from both the ventral and dorsal roots. Next, we detected asymmetric ventral and dorsal root regeneration in response to nerve growth factor (NGF) and glial cell line-derived neurotrophic factor (GDNF), and we observed motor and sensory Schwann cell phenotypes in the regenerated ventral and dorsal roots, respectively. Moreover, based on the SCWR model, we identified a targeted effect of collagen VI on sensory nerve fasciculation and characterized the protein expression profiles correlating to motor/sensory-specific nerve regeneration. These results suggest that the SCWR model can serve as a valuable ex vivo model for comparative study of motor and sensory nerve regeneration and for pharmacodynamic evaluations.
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