1
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Hilton BJ, Griffin JM, Fawcett JW, Bradke F. Neuronal maturation and axon regeneration: unfixing circuitry to enable repair. Nat Rev Neurosci 2024; 25:649-667. [PMID: 39164450 DOI: 10.1038/s41583-024-00849-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/19/2024] [Indexed: 08/22/2024]
Abstract
Mammalian neurons lose the ability to regenerate their central nervous system axons as they mature during embryonic or early postnatal development. Neuronal maturation requires a transformation from a situation in which neuronal components grow and assemble to one in which these components are fixed and involved in the machinery for effective information transmission and computation. To regenerate after injury, neurons need to overcome this fixed state to reactivate their growth programme. A variety of intracellular processes involved in initiating or sustaining neuronal maturation, including the regulation of gene expression, cytoskeletal restructuring and shifts in intracellular trafficking, have been shown to prevent axon regeneration. Understanding these processes will contribute to the identification of targets to promote repair after injury or disease.
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Affiliation(s)
- Brett J Hilton
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, British Columbia, Canada.
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada.
| | - Jarred M Griffin
- Laboratory for Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - James W Fawcett
- Department of Clinical Neurosciences, John van Geest Centre for Brain Repair, University of Cambridge, Cambridge, UK.
- Centre for Reconstructive Neuroscience, Institute for Experimental Medicine Czech Academy of Science (CAS), Prague, Czechia.
| | - Frank Bradke
- Laboratory for Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.
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2
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Fu XQ, Zhan WR, Tian WY, Zeng PM, Luo ZG. Comparative transcriptomic profiling reveals a role for Olig1 in promoting axon regeneration. Cell Rep 2024; 43:114514. [PMID: 39002126 DOI: 10.1016/j.celrep.2024.114514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Revised: 05/21/2024] [Accepted: 06/30/2024] [Indexed: 07/15/2024] Open
Abstract
The regenerative potential of injured axons displays considerable heterogeneity. However, the molecular mechanisms underlying the heterogeneity have not been fully elucidated. Here, we establish a method that can separate spinal motor neurons (spMNs) with low and high regenerative capacities and identify a set of transcripts revealing differential expression between two groups of neurons. Interestingly, oligodendrocyte transcription factor 1 (Olig1), which regulates the differentiation of various neuronal progenitors, exhibits recurrent expression in spMNs with enhanced regenerative capabilities. Furthermore, overexpression of Olig1 (Olig1 OE) facilitates axonal regeneration in various models, and down-regulation or deletion of Olig1 exhibits an opposite effect. By analyzing the overlapped differentially expressed genes after expressing individual Olig factor and functional validation, we find that the role of Olig1 is at least partially through the neurite extension factor 1 (Nrsn1). We therefore identify Olig1 as an intrinsic factor that promotes regenerative capacity of injured axons.
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Affiliation(s)
- Xiu-Qing Fu
- School of Life Science and Technology and State Key Laboratory of Advanced Medical Materials and Devices, ShanghaiTech University, Shanghai 201210, China.
| | - Wen-Rong Zhan
- School of Life Science and Technology and State Key Laboratory of Advanced Medical Materials and Devices, ShanghaiTech University, Shanghai 201210, China
| | - Wei-Ya Tian
- School of Life Science and Technology and State Key Laboratory of Advanced Medical Materials and Devices, ShanghaiTech University, Shanghai 201210, China
| | - Peng-Ming Zeng
- School of Life Science and Technology and State Key Laboratory of Advanced Medical Materials and Devices, ShanghaiTech University, Shanghai 201210, China
| | - Zhen-Ge Luo
- School of Life Science and Technology and State Key Laboratory of Advanced Medical Materials and Devices, ShanghaiTech University, Shanghai 201210, China.
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3
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Cheng YT, Lett KM, Xu C, Schaffer CB. Three-photon excited fluorescence microscopy enables imaging of blood flow, neural structure and inflammatory response deep into mouse spinal cord in vivo. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.04.588110. [PMID: 38617307 PMCID: PMC11014502 DOI: 10.1101/2024.04.04.588110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
Nonlinear optical microscopy enables non-invasive imaging in scattering samples with cellular resolution. The spinal cord connects the brain with the periphery and governs fundamental behaviors such as locomotion and somatosensation. Because of dense myelination on the dorsal surface, imaging to the spinal grey matter is challenging, even with two-photon microscopy. Here we show that three-photon excited fluorescence (3PEF) microscopy enables multicolor imaging at depths of up to ~550 μm into the mouse spinal cord, in vivo. We quantified blood flow across vessel types along the spinal vascular network. We then followed the response of neurites and microglia after occlusion of a surface venule, where we observed depth-dependent structural changes in neurites and interactions of perivascular microglia with vessel branches upstream from the clot. This work establishes that 3PEF imaging enables studies of functional dynamics and cell type interactions in the top 550 μm of the murine spinal cord, in vivo.
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Affiliation(s)
- Yu-Ting Cheng
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, USA
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, USA
| | - Kawasi M. Lett
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, USA
| | - Chris Xu
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
| | - Chris B. Schaffer
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, USA
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4
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Deng J, Sun C, Zheng Y, Gao J, Cui X, Wang Y, Zhang L, Tang P. In vivo imaging of the neuronal response to spinal cord injury: a narrative review. Neural Regen Res 2024; 19:811-817. [PMID: 37843216 PMCID: PMC10664102 DOI: 10.4103/1673-5374.382225] [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: 01/07/2023] [Revised: 05/15/2023] [Accepted: 07/07/2023] [Indexed: 10/17/2023] Open
Abstract
Deciphering the neuronal response to injury in the spinal cord is essential for exploring treatment strategies for spinal cord injury (SCI). However, this subject has been neglected in part because appropriate tools are lacking. Emerging in vivo imaging and labeling methods offer great potential for observing dynamic neural processes in the central nervous system in conditions of health and disease. This review first discusses in vivo imaging of the mouse spinal cord with a focus on the latest imaging techniques, and then analyzes the dynamic biological response of spinal cord sensory and motor neurons to SCI. We then summarize and compare the techniques behind these studies and clarify the advantages of in vivo imaging compared with traditional neuroscience examinations. Finally, we identify the challenges and possible solutions for spinal cord neuron imaging.
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Affiliation(s)
- Junhao Deng
- Department of Orthopedics, The Fourth Medical Center of Chinese PLA General Hospital, Beijing, China
- National Clinical Research Center for Orthopedics, Sports Medicine and Rehabilitation, Beijing, China
- School of Life Sciences, Tsinghua University, Beijing, China
| | - Chang Sun
- Department of Orthopedics, The Fourth Medical Center of Chinese PLA General Hospital, Beijing, China
- National Clinical Research Center for Orthopedics, Sports Medicine and Rehabilitation, Beijing, China
- Department of Orthopedics, Air Force Medical Center, PLA, Beijing, China
| | - Ying Zheng
- Medical School of Chinese PLA, Beijing, China
| | - Jianpeng Gao
- Department of Orthopedics, The Fourth Medical Center of Chinese PLA General Hospital, Beijing, China
- National Clinical Research Center for Orthopedics, Sports Medicine and Rehabilitation, Beijing, China
| | - Xiang Cui
- Department of Orthopedics, The Fourth Medical Center of Chinese PLA General Hospital, Beijing, China
- National Clinical Research Center for Orthopedics, Sports Medicine and Rehabilitation, Beijing, China
| | - Yu Wang
- Institute of Orthopedics, The First Medical Center, Chinese PLA General Hospital, Beijing, China
- Key Lab of Regenerative Medicine in Orthopedics, Key Laboratory of Musculoskeletal Trauma and War Injuries PLA, Beijing, China
| | - Licheng Zhang
- Department of Orthopedics, The Fourth Medical Center of Chinese PLA General Hospital, Beijing, China
- National Clinical Research Center for Orthopedics, Sports Medicine and Rehabilitation, Beijing, China
| | - Peifu Tang
- Department of Orthopedics, The Fourth Medical Center of Chinese PLA General Hospital, Beijing, China
- National Clinical Research Center for Orthopedics, Sports Medicine and Rehabilitation, Beijing, China
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5
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McCracken S, Fitzpatrick MJ, Hall AL, Wang Z, Kerschensteiner D, Morgan JL, Williams PR. Diversity in homeostatic calcium set points predicts retinal ganglion cell survival following optic nerve injury in vivo. Cell Rep 2023; 42:113165. [PMID: 37751356 PMCID: PMC10947246 DOI: 10.1016/j.celrep.2023.113165] [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: 10/17/2022] [Revised: 06/29/2023] [Accepted: 09/07/2023] [Indexed: 09/28/2023] Open
Abstract
Retinal ganglion cell (RGC) degeneration drives vision loss in blinding conditions. RGC death is often triggered by axon degeneration in the optic nerve. Here, we study the contributions of dynamic and homeostatic Ca2+ levels to RGC death from axon injury. We find that axonal Ca2+ elevations from optic nerve injury do not propagate over distance or reach RGC somas, and acute and chronic Ca2+ dynamics do not affect RGC survival. Instead, we discover that baseline Ca2+ levels vary widely between RGCs and predict their survival after axon injury, and that lowering these levels reduces RGC survival. Further, we find that well-surviving RGC types have higher baseline Ca2+ levels than poorly surviving types. Finally, we observe considerable variation in the baseline Ca2+ levels of different RGCs of the same type, which are predictive of within-type differences in survival.
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Affiliation(s)
- Sean McCracken
- John F. Hardesty, MD Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA; Graduate Program in Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Michael J Fitzpatrick
- John F. Hardesty, MD Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA; Graduate Program in Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA; Medical Scientist Training Program, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Allison L Hall
- John F. Hardesty, MD Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA; Postbaccalaureate Program in Developmental Biology & Regenerative Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Zelun Wang
- John F. Hardesty, MD Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA; Graduate Program in Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA; Medical Scientist Training Program, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Daniel Kerschensteiner
- John F. Hardesty, MD Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA; Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Biomedical Engineering, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Josh L Morgan
- John F. Hardesty, MD Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Philip R Williams
- John F. Hardesty, MD Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA; Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA.
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6
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Stewart AN, Kumari R, Bailey WM, Glaser EP, Bosse-Joseph CC, Park KA, Hammers GV, Wireman OH, Gensel JC. PTEN knockout using retrogradely transported AAVs transiently restores locomotor abilities in both acute and chronic spinal cord injury. Exp Neurol 2023; 368:114502. [PMID: 37558155 PMCID: PMC10498341 DOI: 10.1016/j.expneurol.2023.114502] [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: 04/25/2023] [Revised: 07/07/2023] [Accepted: 08/07/2023] [Indexed: 08/11/2023]
Abstract
Restoring function in chronic stages of spinal cord injury (SCI) has often been met with failure or reduced efficacy when regenerative strategies are delayed past the acute or sub-acute stages of injury. Restoring function in the chronically injured spinal cord remains a critical challenge. We found that a single injection of retrogradely transported adeno-associated viruses (AAVrg) to knockout the phosphatase and tensin homolog protein (PTEN) in chronic SCI can effectively target both damaged and spared axons and transiently restore locomotor functions in near-complete injury models. AAVrg's were injected to deliver cre recombinase and/or a red fluorescent protein (RFP) under the human Synapsin 1 promoter (hSyn1) into the spinal cords of C57BL/6 PTENFloxΔ/Δ mice to knockout PTEN (PTEN-KO) in a severe thoracic SCI crush model at both acute and chronic time points. PTEN-KO improved locomotor abilities in both acute and chronic SCI conditions over a 9-week period. Regardless of whether treatment was initiated at the time of injury (acute), or three months after SCI (chronic), mice with limited hindlimb joint movement gained hindlimb weight support after treatment. Interestingly, functional improvements were not sustained beyond 9 weeks coincident with a loss of RFP reporter-gene expression and a near-complete loss of treatment-associated functional recovery by 6 months post-treatment. Treatment effects were also specific to severely injured mice; animals with weight support at the time of treatment lost function over a 6-month period. Retrograde tracing with Fluorogold revealed viable neurons throughout the motor cortex despite a loss of RFP expression at 9 weeks post-PTEN-KO. However, few Fluorogold labeled neurons were detected within the motor cortex at 6 months post-treatment. BDA labeling from the motor cortex revealed a dense corticospinal tract (CST) bundle in all groups except chronically treated PTEN-KO mice, indicating a potential long-term toxic effect of PTEN-KO to neurons in the motor cortex which was corroborated by a loss of β-tubulin III labeling above the lesion within spinal cords after PTEN-KO. PTEN-KO mice had significantly more β-tubulin III labeled axons within the lesion when treatment was delivered acutely, but not chronically post-SCI. In conclusion, we have found that using AAVrg's to knockout PTEN is an effective manipulation capable of restoring motor functions in chronic SCI and can enhance axon growth of currently unidentified axon populations when delivered acutely after injury. However, the long-term consequences of PTEN-KO on neuronal health and viability should be further explored.
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Affiliation(s)
- Andrew N Stewart
- Department of Physiology, University of Kentucky, Lexington, KY 40536, USA; Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, KY 40536, USA.
| | - Reena Kumari
- Department of Physiology, University of Kentucky, Lexington, KY 40536, USA; Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, KY 40536, USA
| | - William M Bailey
- Department of Physiology, University of Kentucky, Lexington, KY 40536, USA; Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, KY 40536, USA
| | - Ethan P Glaser
- Department of Physiology, University of Kentucky, Lexington, KY 40536, USA; Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, KY 40536, USA
| | - Christopher C Bosse-Joseph
- Department of Physiology, University of Kentucky, Lexington, KY 40536, USA; Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, KY 40536, USA
| | - Kennedy A Park
- Department of Physiology, University of Kentucky, Lexington, KY 40536, USA; Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, KY 40536, USA
| | - Gabrielle V Hammers
- Department of Physiology, University of Kentucky, Lexington, KY 40536, USA; Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, KY 40536, USA
| | - Olivia H Wireman
- Department of Physiology, University of Kentucky, Lexington, KY 40536, USA; Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, KY 40536, USA
| | - John C Gensel
- Department of Physiology, University of Kentucky, Lexington, KY 40536, USA; Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, KY 40536, USA; College of Medicine, University of Kentucky, Lexington, KY 40536, USA.
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7
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Kim H, Skuba A, Xia J, Han SB, Zhai J, Hu H, Kang SH, Son YJ. Oligodendrocyte precursor cells stop sensory axons regenerating into the spinal cord. Cell Rep 2023; 42:113068. [PMID: 37656624 DOI: 10.1016/j.celrep.2023.113068] [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: 11/01/2022] [Revised: 07/17/2023] [Accepted: 08/18/2023] [Indexed: 09/03/2023] Open
Abstract
Primary somatosensory axons stop regenerating as they re-enter the spinal cord, resulting in incurable sensory loss. What arrests them has remained unclear. We previously showed that axons stop by forming synaptic contacts with unknown non-neuronal cells. Here, we identified these cells in adult mice as oligodendrocyte precursor cells (OPCs). We also found that only a few axons stop regenerating by forming dystrophic endings, exclusively at the CNS:peripheral nervous system (PNS) borderline where OPCs are absent. Most axons stop in contact with a dense network of OPC processes. Live imaging, immuno-electron microscopy (immuno-EM), and OPC-dorsal root ganglia (DRG) co-culture additionally suggest that axons are rapidly immobilized by forming synapses with OPCs. Genetic OPC ablation enables many axons to continue regenerating deep into the spinal cord. We propose that sensory axons stop regenerating by encountering OPCs that induce presynaptic differentiation. Our findings identify OPCs as a major regenerative barrier that prevents intraspinal restoration of sensory circuits following spinal root injury.
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Affiliation(s)
- Hyukmin Kim
- Department of Neural Sciences, Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Andy Skuba
- Department of Neural Sciences, Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Jingsheng Xia
- Department of Medicine, New Jersey Medical School, Rutgers University, Newark, NJ, USA
| | - Sung Baek Han
- Department of Neural Sciences, Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Jinbin Zhai
- Department of Neural Sciences, Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Huijuan Hu
- Department of Medicine, New Jersey Medical School, Rutgers University, Newark, NJ, USA
| | - Shin H Kang
- Department of Neural Sciences, Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Young-Jin Son
- Department of Neural Sciences, Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA.
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8
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Stewart AN, Kumari R, Bailey WM, Glaser EP, Hammers GV, Wireman OH, Gensel JC. PTEN knockout using retrogradely transported AAVs restores locomotor abilities in both acute and chronic spinal cord injury. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.17.537179. [PMID: 37131840 PMCID: PMC10153160 DOI: 10.1101/2023.04.17.537179] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Restoring function in chronic stages of spinal cord injury (SCI) has often been met with failure or reduced efficacy when regenerative strategies are delayed past the acute or sub-acute stages of injury. Restoring function in the chronically injured spinal cord remains a critical challenge. We found that a single injection of retrogradely transported adeno-associated viruses (AAVrg) to knockout the phosphatase and tensin homolog protein (PTEN) in chronic SCI can effectively target both damaged and spared axons and restore locomotor functions in near-complete injury models. AAVrg's were injected to deliver cre recombinase and/or a red fluorescent protein (RFP) under the human Synapsin 1 promoter (hSyn1) into the spinal cords of C57BL/6 PTEN FloxΔ / Δ mice to knockout PTEN (PTEN-KO) in a severe thoracic SCI crush model at both acute and chronic time points. PTEN-KO improved locomotor abilities in both acute and chronic SCI conditions over a 9-week period. Regardless of whether treatment was initiated at the time of injury (acute), or three months after SCI (chronic), mice with limited hindlimb joint movement gained hindlimb weight support after treatment. Interestingly, functional improvements were not sustained beyond 9 weeks coincident with a loss of RFP reporter-gene expression and a near-complete loss of treatment-associated functional recovery by 6 months post-treatment. Treatment effects were also specific to severely injured mice; animals with weight support at the time of treatment lost function over a 6-month period. Retrograde tracing with Fluorogold revealed viable neurons throughout the motor cortex despite a loss of RFP expression at 9 weeks post-PTEN-KO. However, few Fluorogold labeled neurons were detected within the motor cortex at 6 months post-treatment. BDA labeling from the motor cortex revealed a dense corticospinal tract (CST) bundle in all groups except chronically treated PTEN-KO mice indicating a potential long-term toxic effect of PTEN-KO to neurons in the motor cortex. PTEN-KO mice had significantly more β - tubulin III labeled axons within the lesion when treatment was delivered acutely, but not chronically post-SCI. In conclusion, we have found that using AAVrg's to knockout PTEN is an effective manipulation capable of restoring motor functions in chronic SCI and can enhance axon growth of currently unidentified axon populations when delivered acutely after injury. However, the long-term consequences of PTEN-KO may exert neurotoxic effects.
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Affiliation(s)
- Andrew N. Stewart
- Department of Physiology, University of Kentucky, Lexington, Kentucky 40536, USA
- Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Reena Kumari
- Department of Physiology, University of Kentucky, Lexington, Kentucky 40536, USA
- Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, Kentucky 40536, USA
| | - William M. Bailey
- Department of Physiology, University of Kentucky, Lexington, Kentucky 40536, USA
- Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Ethan P. Glaser
- Department of Physiology, University of Kentucky, Lexington, Kentucky 40536, USA
- Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Gabrielle V. Hammers
- Department of Physiology, University of Kentucky, Lexington, Kentucky 40536, USA
- Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Olivia H. Wireman
- Department of Physiology, University of Kentucky, Lexington, Kentucky 40536, USA
- Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, Kentucky 40536, USA
| | - John C. Gensel
- Department of Physiology, University of Kentucky, Lexington, Kentucky 40536, USA
- Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, Kentucky 40536, USA
- College of Medicine, University of Kentucky, Lexington, Kentucky 40536, USA
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9
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Zheng B, Tuszynski MH. Regulation of axonal regeneration after mammalian spinal cord injury. Nat Rev Mol Cell Biol 2023; 24:396-413. [PMID: 36604586 DOI: 10.1038/s41580-022-00562-y] [Citation(s) in RCA: 57] [Impact Index Per Article: 57.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/04/2022] [Indexed: 01/06/2023]
Abstract
One hundred years ago, Ramón y Cajal, considered by many as the founder of modern neuroscience, stated that neurons of the adult central nervous system (CNS) are incapable of regenerating. Yet, recent years have seen a tremendous expansion of knowledge in the molecular control of axon regeneration after CNS injury. We now understand that regeneration in the adult CNS is limited by (1) a failure to form cellular or molecular substrates for axon attachment and elongation through the lesion site; (2) environmental factors, including inhibitors of axon growth associated with myelin and the extracellular matrix; (3) astrocyte responses, which can both limit and support axon growth; and (4) intraneuronal mechanisms controlling the establishment of an active cellular growth programme. We discuss these topics together with newly emerging hypotheses, including the surprising finding from transcriptomic analyses of the corticospinal system in mice that neurons revert to an embryonic state after spinal cord injury, which can be sustained to promote regeneration with neural stem cell transplantation. These gains in knowledge are steadily advancing efforts to develop effective treatment strategies for spinal cord injury in humans.
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Affiliation(s)
- Binhai Zheng
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, CA, USA. .,VA San Diego Research Service, San Diego, CA, USA.
| | - Mark H Tuszynski
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, CA, USA. .,VA San Diego Research Service, San Diego, CA, USA.
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10
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Costa G, Ribeiro FF, Sebastião AM, Muir EM, Vaz SH. Bridging the gap of axonal regeneration in the central nervous system: A state of the art review on central axonal regeneration. Front Neurosci 2022; 16:1003145. [PMID: 36440273 PMCID: PMC9682039 DOI: 10.3389/fnins.2022.1003145] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 10/19/2022] [Indexed: 08/26/2023] Open
Abstract
Neuronal regeneration in the central nervous system (CNS) is an important field of research with relevance to all types of neuronal injuries, including neurodegenerative diseases. The glial scar is a result of the astrocyte response to CNS injury. It is made up of many components creating a complex environment in which astrocytes play various key roles. The glial scar is heterogeneous, diverse and its composition depends upon the injury type and location. The heterogeneity of the glial scar observed in different situations of CNS damage and the consequent implications for axon regeneration have not been reviewed in depth. The gap in this knowledge will be addressed in this review which will also focus on our current understanding of central axonal regeneration and the molecular mechanisms involved. The multifactorial context of CNS regeneration is discussed, and we review newly identified roles for components previously thought to solely play an inhibitory role in central regeneration: astrocytes and p75NTR and discuss their potential and relevance for deciding therapeutic interventions. The article ends with a comprehensive review of promising new therapeutic targets identified for axonal regeneration in CNS and a discussion of novel ways of looking at therapeutic interventions for several brain diseases and injuries.
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Affiliation(s)
- Gonçalo Costa
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
- Faculdade de Medicina, Universidade do Porto, Porto, Portugal
| | - Filipa F. Ribeiro
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Ana M. Sebastião
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Elizabeth M. Muir
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - Sandra H. Vaz
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
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11
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Gao J, Provencio I, Liu X. Intrinsically photosensitive retinal ganglion cells in glaucoma. Front Cell Neurosci 2022; 16:992747. [PMID: 36212698 PMCID: PMC9537624 DOI: 10.3389/fncel.2022.992747] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 09/05/2022] [Indexed: 11/30/2022] Open
Abstract
Glaucoma is a group of eye diseases afflicting more than 70 million people worldwide. It is characterized by damage to retinal ganglion cells (RGCs) that ultimately leads to the death of the cells and vision loss. The diversity of RGC types has been appreciated for decades, and studies, including ours, have shown that RGCs degenerate and die in a type-specific manner in rodent models of glaucoma. The type-specific loss of RGCs results in differential damage to visual and non-visual functions. One type of RGC, the intrinsically photosensitive retinal ganglion cell (ipRGC), expressing the photopigment melanopsin, serves a broad array of non-visual responses to light. Since its discovery, six subtypes of ipRGC have been described, each contributing to various image-forming and non-image-forming functions such as circadian photoentrainment, the pupillary light reflex, the photic control of mood and sleep, and visual contrast sensitivity. We recently demonstrated a link between type-specific ipRGC survival and behavioral deficits in a mouse model of chronic ocular hypertension. This review focuses on the type-specific ipRGC degeneration and associated behavioral changes in animal models and glaucoma patients. A better understanding of how glaucomatous insult impacts the ipRGC-based circuits will have broad impacts on improving the treatment of glaucoma-associated non-visual disorders.
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Affiliation(s)
- Jingyi Gao
- Department of Biology, University of Virginia, Charlottesville, VA, United States
| | - Ignacio Provencio
- Department of Biology, University of Virginia, Charlottesville, VA, United States
- Department of Ophthalmology, University of Virginia, Charlottesville, VA, United States
- Program in Fundamental Neuroscience, University of Virginia, Charlottesville, VA, United States
| | - Xiaorong Liu
- Department of Biology, University of Virginia, Charlottesville, VA, United States
- Department of Ophthalmology, University of Virginia, Charlottesville, VA, United States
- Program in Fundamental Neuroscience, University of Virginia, Charlottesville, VA, United States
- Department of Psychology, University of Virginia, Charlottesville, VA, United States
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12
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Noristani HN. Intrinsic regulation of axon regeneration after spinal cord injury: Recent advances and remaining challenges. Exp Neurol 2022; 357:114198. [DOI: 10.1016/j.expneurol.2022.114198] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 07/20/2022] [Accepted: 08/02/2022] [Indexed: 11/16/2022]
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13
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Long-term in vivo imaging of mouse spinal cord through an optically cleared intervertebral window. Nat Commun 2022; 13:1959. [PMID: 35414131 PMCID: PMC9005710 DOI: 10.1038/s41467-022-29496-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Accepted: 03/17/2022] [Indexed: 11/08/2022] Open
Abstract
The spinal cord accounts for the main communication pathway between the brain and the peripheral nervous system. Spinal cord injury is a devastating and largely irreversible neurological trauma, and can result in lifelong disability and paralysis with no available cure. In vivo spinal cord imaging in mouse models without introducing immunological artifacts is critical to understand spinal cord pathology and discover effective treatments. We developed a minimally invasive intervertebral window by retaining the ligamentum flavum to protect the underlying spinal cord. By introducing an optical clearing method, we achieve repeated two-photon fluorescence and stimulated Raman scattering imaging at subcellular resolution with up to 15 imaging sessions over 6-167 days and observe no inflammatory response. Using this optically cleared intervertebral window, we study neuron-glia dynamics following laser axotomy and observe strengthened contact of microglia with the nodes of Ranvier during axonal degeneration. By enabling long-term, repetitive, stable, high-resolution and inflammation-free imaging of mouse spinal cord, our method provides a reliable platform in the research aiming at interpretation of spinal cord physiology and pathology.
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14
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Hilton BJ, Husch A, Schaffran B, Lin TC, Burnside ER, Dupraz S, Schelski M, Kim J, Müller JA, Schoch S, Imig C, Brose N, Bradke F. An active vesicle priming machinery suppresses axon regeneration upon adult CNS injury. Neuron 2022; 110:51-69.e7. [PMID: 34706221 PMCID: PMC8730507 DOI: 10.1016/j.neuron.2021.10.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 09/03/2021] [Accepted: 10/01/2021] [Indexed: 12/16/2022]
Abstract
Axons in the adult mammalian central nervous system fail to regenerate after spinal cord injury. Neurons lose their capacity to regenerate during development, but the intracellular processes underlying this loss are unclear. We found that critical components of the presynaptic active zone prevent axon regeneration in adult mice. Transcriptomic analysis combined with live-cell imaging revealed that adult primary sensory neurons downregulate molecular constituents of the synapse as they acquire the ability to rapidly grow their axons. Pharmacogenetic reduction of neuronal excitability stimulated axon regeneration after adult spinal cord injury. Genetic gain- and loss-of-function experiments uncovered that essential synaptic vesicle priming proteins of the presynaptic active zone, but not clostridial-toxin-sensitive VAMP-family SNARE proteins, inhibit axon regeneration. Systemic administration of Baclofen reduced voltage-dependent Ca2+ influx in primary sensory neurons and promoted their regeneration after spinal cord injury. These findings indicate that functional presynaptic active zones constitute a major barrier to axon regeneration.
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Affiliation(s)
- Brett J Hilton
- Laboratory of Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg Campus 1/99, 53127 Bonn, Germany
| | - Andreas Husch
- Laboratory of Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg Campus 1/99, 53127 Bonn, Germany
| | - Barbara Schaffran
- Laboratory of Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg Campus 1/99, 53127 Bonn, Germany
| | - Tien-Chen Lin
- Laboratory of Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg Campus 1/99, 53127 Bonn, Germany
| | - Emily R Burnside
- Laboratory of Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg Campus 1/99, 53127 Bonn, Germany
| | - Sebastian Dupraz
- Laboratory of Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg Campus 1/99, 53127 Bonn, Germany
| | - Max Schelski
- Laboratory of Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg Campus 1/99, 53127 Bonn, Germany
| | - Jisoo Kim
- Laboratory of Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg Campus 1/99, 53127 Bonn, Germany; Department of Stem Cell and Regenerative Biology, Center for Brain Science, and Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | | | - Susanne Schoch
- Institute of Neuropathology, Medical Faculty, University of Bonn, 53105 Bonn, Germany
| | - Cordelia Imig
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Nils Brose
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Frank Bradke
- Laboratory of Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg Campus 1/99, 53127 Bonn, Germany.
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15
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Middleton SJ, Perez-Sanchez J, Dawes JM. The structure of sensory afferent compartments in health and disease. J Anat 2021; 241:1186-1210. [PMID: 34528255 PMCID: PMC9558153 DOI: 10.1111/joa.13544] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 08/12/2021] [Accepted: 08/30/2021] [Indexed: 12/20/2022] Open
Abstract
Primary sensory neurons are a heterogeneous population of cells able to respond to both innocuous and noxious stimuli. Like most neurons they are highly compartmentalised, allowing them to detect, convey and transfer sensory information. These compartments include specialised sensory endings in the skin, the nodes of Ranvier in myelinated axons, the cell soma and their central terminals in the spinal cord. In this review, we will highlight the importance of these compartments to primary afferent function, describe how these structures are compromised following nerve damage and how this relates to neuropathic pain.
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Affiliation(s)
- Steven J Middleton
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | | | - John M Dawes
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
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16
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Nazareth L, St John J, Murtaza M, Ekberg J. Phagocytosis by Peripheral Glia: Importance for Nervous System Functions and Implications in Injury and Disease. Front Cell Dev Biol 2021; 9:660259. [PMID: 33898462 PMCID: PMC8060502 DOI: 10.3389/fcell.2021.660259] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 03/17/2021] [Indexed: 12/30/2022] Open
Abstract
The central nervous system (CNS) has very limited capacity to regenerate after traumatic injury or disease. In contrast, the peripheral nervous system (PNS) has far greater capacity for regeneration. This difference can be partly attributed to variances in glial-mediated functions, such as axon guidance, structural support, secretion of growth factors and phagocytic activity. Due to their growth-promoting characteristic, transplantation of PNS glia has been trialed for neural repair. After peripheral nerve injuries, Schwann cells (SCs, the main PNS glia) phagocytose myelin debris and attract macrophages to the injury site to aid in debris clearance. One peripheral nerve, the olfactory nerve, is unique in that it continuously regenerates throughout life. The olfactory nerve glia, olfactory ensheathing cells (OECs), are the primary phagocytes within this nerve, continuously clearing axonal debris arising from the normal regeneration of the nerve and after injury. In contrast to SCs, OECs do not appear to attract macrophages. SCs and OECs also respond to and phagocytose bacteria, a function likely critical for tackling microbial invasion of the CNS via peripheral nerves. However, phagocytosis is not always effective; inflammation, aging and/or genetic factors may contribute to compromised phagocytic activity. Here, we highlight the diverse roles of SCs and OECs with the focus on their phagocytic activity under physiological and pathological conditions. We also explore why understanding the contribution of peripheral glia phagocytosis may provide us with translational strategies for achieving axonal regeneration of the injured nervous system and potentially for the treatment of certain neurological diseases.
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Affiliation(s)
- Lynn Nazareth
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia.,Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia
| | - James St John
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia.,Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia.,Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, Australia
| | - Mariyam Murtaza
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia.,Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia.,Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, Australia
| | - Jenny Ekberg
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia.,Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia.,Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, Australia
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17
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Savvaki M, Kafetzis G, Kaplanis SI, Ktena N, Theodorakis K, Karagogeos D. Neuronal, but not glial, Contactin 2 negatively regulates axon regeneration in the injured adult optic nerve. Eur J Neurosci 2021; 53:1705-1721. [PMID: 33469963 DOI: 10.1111/ejn.15121] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 12/26/2020] [Accepted: 01/17/2021] [Indexed: 01/09/2023]
Abstract
Mammalian adult neurons of the central nervous system (CNS) display limited ability to regrow axons after trauma. The developmental decline in their regenerative ability has been attributed to both intrinsic and extrinsic factors, including postnatal suppression of transcription factors and non-neuronal inhibitory components, respectively. The cell adhesion molecule Contactin 2 (CNTN2) is expressed in neurons and oligodendrocytes in the CNS. Neuronal CNTN2 is highly regulated during development and plays critical roles in axon growth and guidance and neuronal migration. On the other hand, CNTN2 expressed by oligodendrocytes interferes with the myelination process, with its ablation resulting in hypomyelination. In the current study, we investigate the role of CNTN2 in neuronal survival and axon regeneration after trauma, in the murine optic nerve crush (ONC) model. We unveil distinct roles for neuronal and glial CNTN2 in regenerative responses. Surprisingly, our data show a conflicting role of neuronal and glial CNTN2 in axon regeneration. Although glial CNTN2 as well as hypomyelination are dispensable for both neuronal survival and axon regeneration following ONC, the neuronal counterpart comprises a negative regulator of regeneration. Specifically, we reveal a novel mechanism of action for neuronal CNTN2, implicating the inhibition of Akt signalling pathway. The in vitro analysis indicates a BDNF-independent mode of action and biochemical data suggest the implication of the truncated form of TrkB neurotrophin receptor. In conclusion, CNTN2 expressed in CNS neurons serves as an inhibitor of axon regeneration after trauma and its mechanism of action involves the neutralization of Akt-mediated neuroprotective effects.
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Affiliation(s)
- Maria Savvaki
- Department of Basic Science, Faculty of Medicine, University of Crete, Crete, Greece.,Institute of Molecular Biology & Biotechnology - FoRTH, Heraklion, Crete, Greece
| | - George Kafetzis
- Department of Biology, University of Crete, Crete, Greece.,School of Life Sciences, University of Sussex, Brighton, UK
| | - Stefanos-Ioannis Kaplanis
- Department of Basic Science, Faculty of Medicine, University of Crete, Crete, Greece.,Institute of Molecular Biology & Biotechnology - FoRTH, Heraklion, Crete, Greece
| | - Niki Ktena
- Department of Basic Science, Faculty of Medicine, University of Crete, Crete, Greece.,Institute of Molecular Biology & Biotechnology - FoRTH, Heraklion, Crete, Greece
| | - Kostas Theodorakis
- Institute of Molecular Biology & Biotechnology - FoRTH, Heraklion, Crete, Greece
| | - Domna Karagogeos
- Department of Basic Science, Faculty of Medicine, University of Crete, Crete, Greece.,Institute of Molecular Biology & Biotechnology - FoRTH, Heraklion, Crete, Greece
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18
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Ewan EE, Avraham O, Carlin D, Gonçalves TM, Zhao G, Cavalli V. Ascending dorsal column sensory neurons respond to spinal cord injury and downregulate genes related to lipid metabolism. Sci Rep 2021; 11:374. [PMID: 33431991 PMCID: PMC7801468 DOI: 10.1038/s41598-020-79624-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 12/07/2020] [Indexed: 02/08/2023] Open
Abstract
Regeneration failure after spinal cord injury (SCI) results in part from the lack of a pro-regenerative response in injured neurons, but the response to SCI has not been examined specifically in injured sensory neurons. Using RNA sequencing of dorsal root ganglion, we determined that thoracic SCI elicits a transcriptional response distinct from sciatic nerve injury (SNI). Both SNI and SCI induced upregulation of ATF3 and Jun, yet this response failed to promote growth in sensory neurons after SCI. RNA sequencing of purified sensory neurons one and three days after injury revealed that unlike SNI, the SCI response is not sustained. Both SCI and SNI elicited the expression of ATF3 target genes, with very little overlap between conditions. Pathway analysis of differentially expressed ATF3 target genes revealed that fatty acid biosynthesis and terpenoid backbone synthesis were downregulated after SCI but not SNI. Pharmacologic inhibition of fatty acid synthase, the enzyme generating palmitic acid, decreased axon growth and regeneration in vitro. These results support the notion that decreased expression of lipid metabolism-related genes after SCI, including fatty acid synthase, may restrict axon regenerative capacity after SCI.
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Affiliation(s)
- Eric E Ewan
- Department of Neuroscience, Washington University School of Medicine, 660 S. Euclid Ave, Campus Box 8108, St. Louis, MO, 63110-1093, USA
| | - Oshri Avraham
- Department of Neuroscience, Washington University School of Medicine, 660 S. Euclid Ave, Campus Box 8108, St. Louis, MO, 63110-1093, USA
| | - Dan Carlin
- Department of Neuroscience, Washington University School of Medicine, 660 S. Euclid Ave, Campus Box 8108, St. Louis, MO, 63110-1093, USA
| | - Tassia Mangetti Gonçalves
- Department of Neuroscience, Washington University School of Medicine, 660 S. Euclid Ave, Campus Box 8108, St. Louis, MO, 63110-1093, USA
| | - Guoyan Zhao
- Department of Neuroscience, Washington University School of Medicine, 660 S. Euclid Ave, Campus Box 8108, St. Louis, MO, 63110-1093, USA
| | - Valeria Cavalli
- Department of Neuroscience, Washington University School of Medicine, 660 S. Euclid Ave, Campus Box 8108, St. Louis, MO, 63110-1093, USA. .,Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO, 63110, USA. .,Center of Regenerative Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA.
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19
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Lee B, Cho Y. Experimental Model Systems for Understanding Human Axonal Injury Responses. Int J Mol Sci 2021; 22:E474. [PMID: 33418850 PMCID: PMC7824864 DOI: 10.3390/ijms22020474] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 12/03/2020] [Accepted: 12/30/2020] [Indexed: 12/26/2022] Open
Abstract
Neurons are structurally unique and have dendrites and axons that are vulnerable to injury. Some neurons in the peripheral nervous system (PNS) can regenerate their axons after injuries. However, most neurons in the central nervous system (CNS) fail to do so, resulting in irreversible neurological disorders. To understand the mechanisms of axon regeneration, various experimental models have been utilized in vivo and in vitro. Here, we collate the key experimental models that revealed the important mechanisms regulating axon regeneration and degeneration in different systems. We also discuss the advantages of experimenting with the rodent model, considering the application of these findings in understanding human diseases and for developing therapeutic methods.
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Affiliation(s)
| | - Yongcheol Cho
- Laboratory of Axon Regeneration & Degeneration, Department of Life Sciences, Korea University, Anam-ro 145, Seongbuk-gu, Seoul 02841, Korea;
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20
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El Waly B, Escarrat V, Perez-Sanchez J, Kaur J, Pelletier F, Collazos-Castro JE, Debarbieux F. Intravital Assessment of Cells Responses to Conducting Polymer-Coated Carbon Microfibres for Bridging Spinal Cord Injury. Cells 2021; 10:cells10010073. [PMID: 33466339 PMCID: PMC7824803 DOI: 10.3390/cells10010073] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Revised: 12/27/2020] [Accepted: 12/29/2020] [Indexed: 12/18/2022] Open
Abstract
The extension of the lesion following spinal cord injury (SCI) poses a major challenge for regenerating axons, which must grow across several centimetres of damaged tissue in the absence of ordered guidance cues. Biofunctionalized electroconducting microfibres (MFs) that provide biochemical signals, as well as electrical and mechanical cues, offer a promising therapeutic approach to help axons overcome this blind journey. We used poly(3,4-ethylenedioxythiophene)-coated carbon MFs functionalized with cell adhesion molecules and growth factors to bridge the spinal cord after a partial unilateral dorsal quadrant lesion (PUDQL) in mice and followed cellular responses by intravital two-photon (2P) imaging through a spinal glass window. Thy1-CFP//LysM-EGFP//CD11c-EYFP triple transgenic reporter animals allowed real time simultaneous monitoring of axons, myeloid cells and microglial cells in the vicinity of the implanted MFs. MF biocompatibility was confirmed by the absence of inflammatory storm after implantation. We found that the sprouting of sensory axons was significantly accelerated by the implantation of functionalized MFs after PUDQL. Their implantation produced better axon alignment compared to random and misrouted axon regeneration that occurred in the absence of MF, with a most striking effect occurring two months after injury. Importantly, we observed differences in the intensity and composition of the innate immune response in comparison to PUDQL-only animals. A significant decrease of immune cell density was found in MF-implanted mice one month after lesion along with a higher ratio of monocyte-derived dendritic cells whose differentiation was accelerated. Therefore, functionalized carbon MFs promote the beneficial immune responses required for neural tissue repair, providing an encouraging strategy for SCI management.
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Affiliation(s)
- Bilal El Waly
- Institut des Neurosciences de la Timone (UMR7289), Aix-Marseille Université and Centre National de la Recherche Scientifique, 13005 Marseille, France; (B.E.W.); (V.E.); (J.P.-S.); (J.K.); (F.P.)
- Centre Européen de Recherche en Imagerie Médicale, Aix-Marseille Université, 13005 Marseille, France
| | - Vincent Escarrat
- Institut des Neurosciences de la Timone (UMR7289), Aix-Marseille Université and Centre National de la Recherche Scientifique, 13005 Marseille, France; (B.E.W.); (V.E.); (J.P.-S.); (J.K.); (F.P.)
- Centre Européen de Recherche en Imagerie Médicale, Aix-Marseille Université, 13005 Marseille, France
| | - Jimena Perez-Sanchez
- Institut des Neurosciences de la Timone (UMR7289), Aix-Marseille Université and Centre National de la Recherche Scientifique, 13005 Marseille, France; (B.E.W.); (V.E.); (J.P.-S.); (J.K.); (F.P.)
- Centre Européen de Recherche en Imagerie Médicale, Aix-Marseille Université, 13005 Marseille, France
| | - Jaspreet Kaur
- Institut des Neurosciences de la Timone (UMR7289), Aix-Marseille Université and Centre National de la Recherche Scientifique, 13005 Marseille, France; (B.E.W.); (V.E.); (J.P.-S.); (J.K.); (F.P.)
- Centre Européen de Recherche en Imagerie Médicale, Aix-Marseille Université, 13005 Marseille, France
- Department of Neuroscience, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Florence Pelletier
- Institut des Neurosciences de la Timone (UMR7289), Aix-Marseille Université and Centre National de la Recherche Scientifique, 13005 Marseille, France; (B.E.W.); (V.E.); (J.P.-S.); (J.K.); (F.P.)
- Centre Européen de Recherche en Imagerie Médicale, Aix-Marseille Université, 13005 Marseille, France
| | - Jorge Eduardo Collazos-Castro
- Neural Repair and Biomaterials Laboratory, Hospital Nacional de Parapléjicos (SESCAM), 45071 Toledo, Spain
- Correspondence: (J.C.-C.); (F.D.); Tel.:+34-925-247758 (J.C.-C.); +33-491-324186 (F.D.)
| | - Franck Debarbieux
- Institut des Neurosciences de la Timone (UMR7289), Aix-Marseille Université and Centre National de la Recherche Scientifique, 13005 Marseille, France; (B.E.W.); (V.E.); (J.P.-S.); (J.K.); (F.P.)
- Centre Européen de Recherche en Imagerie Médicale, Aix-Marseille Université, 13005 Marseille, France
- Institut Universitaire de France, 75005 Paris, France
- Correspondence: (J.C.-C.); (F.D.); Tel.:+34-925-247758 (J.C.-C.); +33-491-324186 (F.D.)
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21
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Zhang N, Lin J, Chin JS, Zhang K, Chew SY. A laser microdissection-based axotomy model incorporating the use of biomimicking fiber scaffolds reveals that microRNAs promote axon regeneration over long injury distances. Biomater Sci 2020; 8:6286-6300. [PMID: 33020773 DOI: 10.1039/d0bm01380c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The regeneration of injured neurons over long injury distances remains suboptimal. In order to successfully stimulate nerve regrowth, potent biomolecules are necessary. Furthermore, reproducible and translatable methods to test the potency of candidate drugs for enhancing nerve regeneration over long axotomy distances are also needed. To address these issues, we report a novel laser microdissection-based axotomy model that involves the use of biomimicking aligned fiber substrates to precisely control neuronal axotomy distances. Correspondingly, we demonstrate that in the absence of therapeutics, dorsal root ganglion (DRG) explants (consisting of neurons) axotomized within short distances from the main cell somas regenerated significantly longer than axons that were injured more distally (p < 0.05). However, when treated with a cocktail of microRNAs (miR-132/miR-222/miR-431), robust neurite outgrowth was observed (p < 0.05). Specifically, microRNA treatment promoted neurite outgrowth by ∼2.2-fold as compared to untreated cells and this enhancement was more significant under the less conducive regeneration condition of a long axotomy distance (i.e. 1000 μm from the cell soma). Besides that, we demonstrated that the treatment of miR-132/miR-222/miR-431 led to a longer length of nerve regeneration as well as a bigger nerve extension area after sciatic nerve transection injury. These results indicate that distance effects on axonal regrowth may be overcome by the effects of microRNAs and that these microRNAs may serve as promising therapeutics for nerve injury treatment.
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Affiliation(s)
- Na Zhang
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459
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22
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Canty AJ, Jackson JS, Huang L, Trabalza A, Bass C, Little G, Tortora M, Khan S, De Paola V. In vivo imaging of injured cortical axons reveals a rapid onset form of Wallerian degeneration. BMC Biol 2020; 18:170. [PMID: 33208154 PMCID: PMC7677840 DOI: 10.1186/s12915-020-00869-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 09/16/2020] [Indexed: 12/22/2022] Open
Abstract
Background Despite the widespread occurrence of axon and synaptic loss in the injured and diseased nervous system, the cellular and molecular mechanisms of these key degenerative processes remain incompletely understood. Wallerian degeneration (WD) is a tightly regulated form of axon loss after injury, which has been intensively studied in large myelinated fibre tracts of the spinal cord, optic nerve and peripheral nervous system (PNS). Fewer studies, however, have focused on WD in the complex neuronal circuits of the mammalian brain, and these were mainly based on conventional endpoint histological methods. Post-mortem analysis, however, cannot capture the exact sequence of events nor can it evaluate the influence of elaborated arborisation and synaptic architecture on the degeneration process, due to the non-synchronous and variable nature of WD across individual axons. Results To gain a comprehensive picture of the spatiotemporal dynamics and synaptic mechanisms of WD in the nervous system, we identify the factors that regulate WD within the mouse cerebral cortex. We combined single-axon-resolution multiphoton imaging with laser microsurgery through a cranial window and a fluorescent membrane reporter. Longitudinal imaging of > 150 individually injured excitatory cortical axons revealed a threshold length below which injured axons consistently underwent a rapid-onset form of WD (roWD). roWD started on average 20 times earlier and was executed 3 times slower than WD described in other regions of the nervous system. Cortical axon WD and roWD were dependent on synaptic density, but independent of axon complexity. Finally, pharmacological and genetic manipulations showed that a nicotinamide adenine dinucleotide (NAD+)-dependent pathway could delay cortical roWD independent of transcription in the damaged neurons, demonstrating further conservation of the molecular mechanisms controlling WD in different areas of the mammalian nervous system. Conclusions Our data illustrate how in vivo time-lapse imaging can provide new insights into the spatiotemporal dynamics and synaptic mechanisms of axon loss and assess therapeutic interventions in the injured mammalian brain.
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Affiliation(s)
- Alison Jane Canty
- Wicking Dementia Research and Education Centre, University of Tasmania, Hobart, Australia.
| | - Johanna Sara Jackson
- Dementia Research Institute at Imperial College, Department of Brain Sciences, Imperial College London, London, W12 0NN, UK
| | - Lieven Huang
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | - Antonio Trabalza
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | - Cher Bass
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | - Graham Little
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | - Maria Tortora
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | - Shabana Khan
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | - Vincenzo De Paola
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, W12 0NN, UK. .,Medical Research Council London Institute of Medical Sciences, London, W12 0NN, UK.
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23
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Kiyoshi C, Tedeschi A. Axon growth and synaptic function: A balancing act for axonal regeneration and neuronal circuit formation in CNS trauma and disease. Dev Neurobiol 2020; 80:277-301. [PMID: 32902152 PMCID: PMC7754183 DOI: 10.1002/dneu.22780] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 08/29/2020] [Accepted: 08/31/2020] [Indexed: 12/13/2022]
Abstract
Axons in the adult mammalian central nervous system (CNS) fail to regenerate inside out due to intrinsic and extrinsic neuronal determinants. During CNS development, axon growth, synapse formation, and function are tightly regulated processes allowing immature neurons to effectively grow an axon, navigate toward target areas, form synaptic contacts and become part of information processing networks that control behavior in adulthood. Not only immature neurons are able to precisely control the expression of a plethora of genes necessary for axon extension and pathfinding, synapse formation and function, but also non-neuronal cells such as astrocytes and microglia actively participate in sculpting the nervous system through refinement, consolidation, and elimination of synaptic contacts. Recent evidence indicates that a balancing act between axon regeneration and synaptic function may be crucial for rebuilding functional neuronal circuits after CNS trauma and disease in adulthood. Here, we review the role of classical and new intrinsic and extrinsic neuronal determinants in the context of CNS development, injury, and disease. Moreover, we discuss strategies targeting neuronal and non-neuronal cell behaviors, either alone or in combination, to promote axon regeneration and neuronal circuit formation in adulthood.
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Affiliation(s)
- Conrad Kiyoshi
- Department of Neuroscience, Wexner Medical Center, The Ohio State University, Columbus, OH 43210, USA
| | - Andrea Tedeschi
- Department of Neuroscience, Wexner Medical Center, The Ohio State University, Columbus, OH 43210, USA
- Discovery Theme on Chronic Brain Injury, The Ohio State University, Columbus, OH 43210, USA
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24
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Han W, Li Y, Cheng J, Zhang J, Chen D, Fang M, Xiang G, Wu Y, Zhang H, Xu K, Wang H, Xie L, Xiao J. Sitagliptin improves functional recovery via GLP-1R-induced anti-apoptosis and facilitation of axonal regeneration after spinal cord injury. J Cell Mol Med 2020; 24:8687-8702. [PMID: 32573108 PMCID: PMC7412681 DOI: 10.1111/jcmm.15501] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Revised: 05/18/2020] [Accepted: 05/28/2020] [Indexed: 12/18/2022] Open
Abstract
Axon growth and neuronal apoptosis are considered to be crucial therapeutic targets against spinal cord injury (SCI). Growing evidences have reported stimulation of glucagon‐like peptide‐1 (GLP‐1)/GLP‐1 receptor (GLP‐1R) signalling axis provides neuroprotection in experimental models of neurodegeneration disease. Endogenous GLP‐1 is rapidly degraded by dipeptidyl peptidase‐IV (DPP4), resulting in blocking of GLP‐1/GLP1R signalling process. Sitagliptin, a highly selective inhibitor of DPP4, has approved to have beneficial effects on diseases in which neurons damaged. However, the roles and the underlying mechanisms of sitagliptin in SCI repairing remain unclear. In this study, we used a rat model of SCI and PC12 cells/primary cortical neurons to explore the mechanism of sitagliptin underlying SCI recovery. We discovered the expression of GLP‐1R decreased in the SCI model. Administration of sitagliptin significantly increased GLP‐1R protein level, alleviated neuronal apoptosis, enhanced axon regeneration and improved functional recovery following SCI. Nevertheless, treatment with exendin9‐39, a GLP‐1R inhibitor, remarkably reversed the protective effect of sitagliptin. Additionally, we detected the AMPK/PGC‐1α signalling pathway was activated by sitagliptin stimulating GLP‐1R. Taken together, sitagliptin may be a potential agent for axon regrowth and locomotor functional repair via GLP‐1R‐induced AMPK/ PGC‐1α signalling pathway after SCI.
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Affiliation(s)
- Wen Han
- Molecular Pharmacology Research Center, School of Pharmaceutical Science, Wenzhou Medical University, Wenzhou, China
| | - Yao Li
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Jiangting Cheng
- Key Laboratory of Combined Multi-Organ Transplantation, Ministry of Public Health, School of Medicine, The First Affiliated Hospital, Zhejiang University, Hangzhou, China
| | - Jing Zhang
- Molecular Pharmacology Research Center, School of Pharmaceutical Science, Wenzhou Medical University, Wenzhou, China
| | - Dingwen Chen
- Molecular Pharmacology Research Center, School of Pharmaceutical Science, Wenzhou Medical University, Wenzhou, China
| | - Mingqiao Fang
- Molecular Pharmacology Research Center, School of Pharmaceutical Science, Wenzhou Medical University, Wenzhou, China.,Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Guangheng Xiang
- Molecular Pharmacology Research Center, School of Pharmaceutical Science, Wenzhou Medical University, Wenzhou, China.,Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Yanqing Wu
- Engineering Laboratory of Zhejiang Province for Pharmaceutical Development of Growth Factors, Biomedical Collaborative Innovation Center of Wenzhou, The Institute of Life Sciences, Wenzhou University, Wenzhou, China
| | - Hongyu Zhang
- Molecular Pharmacology Research Center, School of Pharmaceutical Science, Wenzhou Medical University, Wenzhou, China
| | - Ke Xu
- Engineering Laboratory of Zhejiang Province for Pharmaceutical Development of Growth Factors, Biomedical Collaborative Innovation Center of Wenzhou, The Institute of Life Sciences, Wenzhou University, Wenzhou, China
| | - Hangxiang Wang
- Key Laboratory of Combined Multi-Organ Transplantation, Ministry of Public Health, School of Medicine, The First Affiliated Hospital, Zhejiang University, Hangzhou, China
| | - Ling Xie
- Molecular Pharmacology Research Center, School of Pharmaceutical Science, Wenzhou Medical University, Wenzhou, China
| | - Jian Xiao
- Molecular Pharmacology Research Center, School of Pharmaceutical Science, Wenzhou Medical University, Wenzhou, China
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25
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McCann MM, Fisher KM, Ahloy-Dallaire J, Darian-Smith C. Somatosensory corticospinal tract axons sprout within the cervical cord following a dorsal root/dorsal column spinal injury in the rat. J Comp Neurol 2020; 528:1293-1306. [PMID: 31769033 PMCID: PMC7102935 DOI: 10.1002/cne.24826] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 11/18/2019] [Accepted: 11/20/2019] [Indexed: 12/19/2022]
Abstract
The corticospinal tract (CST) is the major descending pathway controlling voluntary hand function in primates, and though less dominant, it mediates voluntary paw movements in rats. As with primates, the CST in rats originates from multiple (albeit fewer) cortical sites, and functionally different motor and somatosensory subcomponents terminate in different regions of the spinal gray matter. We recently reported in monkeys that following a combined cervical dorsal root/dorsal column lesion (DRL/DCL), both motor and S1 CSTs sprout well beyond their normal terminal range. The S1 CST sprouting response is particularly dramatic, indicating an important, if poorly understood, somatosensory role in the recovery process. As rats are used extensively to model spinal cord injury, we asked if the S1 CST response is conserved in rodents. Rats were divided into sham controls, and two groups surviving post-lesion for ~6 and 10 weeks. A DRL/DCL was made to partially deafferent one paw. Behavioral testing showed a post-lesion deficit and recovery over several weeks. Three weeks prior to ending the experiment, S1 cortex was mapped electrophysiologically, for tracer injection placement to determine S1 CST termination patterns within the cord. Synaptogenesis was also assessed for labeled S1 CST terminals within the dorsal horn. Our findings show that the affected S1 CST sprouts well beyond its normal range in response to a DRL/DCL, much as it does in macaque monkeys. This, along with evidence for increased synaptogenesis post-lesion, indicates that CST terminal sprouting following a central sensory lesion, is a robust and conserved response.
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Affiliation(s)
- Margaret M. McCann
- Department of Comparative Medicine, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA94305-5342
- Margaret M. McCann, Creighton University, Department of Biomedical Sciences, 2500 California Plaza, Criss II, Omaha NE 68178
| | - Karen M. Fisher
- Department of Comparative Medicine, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA94305-5342
| | - Jamie Ahloy-Dallaire
- Department of Comparative Medicine, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA94305-5342
- Département des sciences animales, Université Laval, 2425 rue de l’Agriculture, Québec, Québec, Canada G1V 0A6
| | - Corinna Darian-Smith
- Department of Comparative Medicine, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA94305-5342
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26
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Imperadore P, Uckermann O, Galli R, Steiner G, Kirsch M, Fiorito G. Nerve regeneration in the cephalopod mollusc Octopus vulgaris: label-free multiphoton microscopy as a tool for investigation. J R Soc Interface 2019; 15:rsif.2017.0889. [PMID: 29643223 DOI: 10.1098/rsif.2017.0889] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 03/16/2018] [Indexed: 01/16/2023] Open
Abstract
Octopus and cephalopods are able to regenerate injured tissues. Recent advancements in the study of regeneration in cephalopods appear promising encompassing different approaches helping to decipher cellular and molecular machinery involved in the process. However, lack of specific markers to investigate degenerative/regenerative phenomena and inflammatory events occurring after damage is limiting these studies. Label-free multiphoton microscopy is applied for the first time to the transected pallial nerve of Octopus vulgaris Various optical contrast methods including coherent anti-Stokes Raman scattering (CARS), endogenous two-photon excited fluorescence (TPEF) and second harmonic generation (SHG) have been used. We detected cells and structures often not revealed with classical staining methods. CARS highlighted the involvement of haemocytes in building up scar tissue; CARS and TPEF facilitated the identification of degenerating fibres; SHG allowed visualization of fibrillary collagen, revealing the formation of a connective tissue bridge between the nerve stumps, likely involved in axon guidance. Using label-free multiphoton microscopy, we studied the regenerative events in octopus without using any other labelling techniques. These imaging methods provided extremely helpful morpho-chemical information to describe regeneration events. The techniques applied here are species-specific independent and should facilitate the comparison among various animal species.
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Affiliation(s)
- Pamela Imperadore
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, 80121 Napoli, Italy .,Association for Cephalopod Research - CephRes, 80133 Napoli, Italy
| | - Ortrud Uckermann
- Department of Neurosurgery, University Hospital Carl Gustav Carus and Faculty of Medicine, TU Dresden, Dresden, Germany
| | - Roberta Galli
- Clinical Sensoring and Monitoring, Department of Anesthesiology and Intensive Care Medicine, Faculty of Medicine, TU Dresden, Dresden, Germany
| | - Gerald Steiner
- Clinical Sensoring and Monitoring, Department of Anesthesiology and Intensive Care Medicine, Faculty of Medicine, TU Dresden, Dresden, Germany
| | - Matthias Kirsch
- Department of Neurosurgery, University Hospital Carl Gustav Carus and Faculty of Medicine, TU Dresden, Dresden, Germany.,CRTD/DFG-Center for Regenerative Therapies Dresden - Cluster of Excellence, TU Dresden, Dresden, Germany
| | - Graziano Fiorito
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, 80121 Napoli, Italy
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27
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Wang C, Gong Z, Huang X, Wang J, Xia K, Ying L, Shu J, Yu C, Zhou X, Li F, Liang C, Chen Q. An injectable heparin-Laponite hydrogel bridge FGF4 for spinal cord injury by stabilizing microtubule and improving mitochondrial function. Am J Cancer Res 2019; 9:7016-7032. [PMID: 31660084 PMCID: PMC6815951 DOI: 10.7150/thno.37601] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 07/25/2019] [Indexed: 12/13/2022] Open
Abstract
Rationale: Spinal cord injury (SCI) remains a critical clinical challenge. The controlled release of FGF4, a novel neuroprotective factor, from a versatile Laponite hydrogel to the injured site was a promising strategy to promote axon regeneration and motor functional recovery after SCI. Methods: Characterization of Laponite, Laponite/Heparin (Lap/Hep) and Laponite/Heparin loaded with FGF4 (Lap/Hep@FGF4) hydrogels were measured by rheometer. Multiple comprehensive evaluations were used to detect motor functional recovery and the axonal rehabilitation after Lap/Hep@FGF4 treatment in vivo (SCI rat model). Moreover, microtubule dynamic and energy transportation, which regulated axonal regeneration was evaluated by Lap/Hep@FGF4 gel in vitro (primary neuron). Results: FGF4 released from Lap/Hep gel locally achieves strong protection and regeneration after SCI. The Lap/Hep@FGF4 group revealed remarkable motor functional recovery and axonal regrowth after SCI through suppressing inflammatory reaction, increasing remyelination and reducing glial/fibrotic scars. Furthermore, the underlying mechanism of axonal rehabilitation were demonstrated via enhancing microtubule stability and regulating mitochondrial localization after Lap/Hep@FGF4 treatment. Conclusion: This promising sustained release system provides a synergistic effective approach to enhance recovery after SCI underlying a novel mechanism of axonal rehabilitation, and shows a translational prospect for the clinical treatment of SCI.
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28
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Combining molecular intervention with in vivo imaging to untangle mechanisms of axon pathology and outgrowth following spinal cord injury. Exp Neurol 2019; 318:1-11. [DOI: 10.1016/j.expneurol.2019.04.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 03/20/2019] [Accepted: 04/07/2019] [Indexed: 12/17/2022]
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29
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Chen C, Zhang J, Sun L, Zhang Y, Gan WB, Tang P, Yang G. Long-term imaging of dorsal root ganglia in awake behaving mice. Nat Commun 2019; 10:3087. [PMID: 31300648 PMCID: PMC6625980 DOI: 10.1038/s41467-019-11158-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 06/26/2019] [Indexed: 01/26/2023] Open
Abstract
The dorsal root ganglia (DRG) contain the somas of first-order sensory neurons critical for somatosensation. Due to technical difficulties, DRG neuronal activity in awake behaving animals remains unknown. Here, we develop a method for imaging DRG at cellular and subcellular resolution over weeks in awake mice. The method involves the installation of an intervertebral fusion mount to reduce spinal movement, and the implantation of a vertebral glass window without interfering animals' motor and sensory functions. In vivo two-photon calcium imaging shows that DRG neuronal activity is higher in awake than anesthetized animals. Immediately after plantar formalin injection, DRG neuronal activity increases substantially and this activity upsurge correlates with animals' phasic pain behavior. Repeated imaging of DRG over 5 weeks after formalin injection reveals persistent neuronal hyperactivity associated with ongoing pain. The method described here provides an important means for in vivo studies of DRG functions in sensory perception and disorders.
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Affiliation(s)
- Chao Chen
- Department of Orthopaedics, Peking 301 Hospital, Beijing, 100853, China
| | - Jinhui Zhang
- Department of Orthopaedics, the Affiliated Southeast Hospital of Xiamen University, Zhangzhou 175 Hospital, Zhangzhou, 363000, China
| | - Linlin Sun
- Department of Anesthesiology, Columbia University, New York, 10032, NY, USA
| | - Yiling Zhang
- Department of Orthopaedics, Peking 301 Hospital, Beijing, 100853, China
| | - Wen-Biao Gan
- Department of Neuroscience and Physiology, Department of Anesthesiology, Skirball Institute, New York University School of Medicine, New York, 10016, NY, USA.
| | - Peifu Tang
- Department of Orthopaedics, Peking 301 Hospital, Beijing, 100853, China.
| | - Guang Yang
- Department of Anesthesiology, Columbia University, New York, 10032, NY, USA.
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30
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Evans TA, Barkauskas DS, Silver J. Intravital imaging of immune cells and their interactions with other cell types in the spinal cord: Experiments with multicolored moving cells. Exp Neurol 2019; 320:112972. [PMID: 31234058 DOI: 10.1016/j.expneurol.2019.112972] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 05/25/2019] [Accepted: 06/04/2019] [Indexed: 12/25/2022]
Abstract
Intravital imaging of the immune system is a powerful technique for studying biology of the immune response in the spinal cord using a variety of disease models ranging from traumatic injury to autoimmune disorders. Here, we will discuss specific technical aspects as well as many intriguing biological phenomena that have been revealed with the use of intravital imaging for investigation of the immune system in the spinal cord. We will discuss surgical techniques for exposing and stabilizing the spine that are critical for obtaining images, visualizing immune and CNS cells with genetically expressed fluorescent proteins, fluorescent labeling techniques and briefly discuss some of the challenges of image analysis.
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Affiliation(s)
- Teresa A Evans
- Department of Pediatrics, Stanford University, Stanford, CA, USA.
| | | | - Jerry Silver
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH, USA
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31
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Imaging the execution phase of neuroinflammatory disease models. Exp Neurol 2019; 320:112968. [PMID: 31152743 DOI: 10.1016/j.expneurol.2019.112968] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 05/22/2019] [Accepted: 05/28/2019] [Indexed: 12/15/2022]
Abstract
In vivo imaging of the rodent spinal cord has advanced our understanding of how resident cells of the central nervous system (CNS) respond to neuroinflammation. By combining two-photon imaging and experimental autoimmune encephalomyelitis (EAE), the most widely used rodent model of multiple sclerosis (MS), it has been possible, for example, to study how axons degenerate when confronted with inflammatory cells, how oligodendrocytes get damaged in inflammatory lesions, and how immune cells themselves adapt their phenotype and functionality to the changing lesion environment. Similar approaches are now increasingly used to study other forms of neuroinflammation, such as antibody/complement-mediated neuromyelitis optica spectrum disease (NMOSD). To tackle the most pressing open questions in the field, new biosensors and indicator mice that report the metabolic state and interaction of cells in neuroinflammatory lesions are being developed. Moreover, the field is moving towards new anatomical sites of inflammation, such as the cortical gray matter, but also towards longer observation intervals to reveal the chronic perturbations and adaptations that characterize advanced stages of MS.
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32
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Cheng YT, Lett KM, Schaffer CB. Surgical preparations, labeling strategies, and optical techniques for cell-resolved, in vivo imaging in the mouse spinal cord. Exp Neurol 2019; 318:192-204. [PMID: 31095935 DOI: 10.1016/j.expneurol.2019.05.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 04/25/2019] [Accepted: 05/10/2019] [Indexed: 11/16/2022]
Abstract
In vivo optical imaging has enabled detailed studies of cellular dynamics in the brain of rodents in both healthy and diseased states. Such studies were made possible by three advances: surgical preparations that give optical access to the brain; strategies for in vivo labeling of cells with structural and functional fluorescent indicators; and optical imaging techniques that are relatively insensitive to light scattering by tissue. In vivo imaging in the rodent spinal cord has lagged behind than that in the brain, largely due to the anatomy around the spinal cord that complicates the surgical preparation, and to the strong optical scattering of the dorsal white matter that limits the ability to image deep into the spinal cord. Here, we review recent advances in surgical methods, labeling strategies, and optical tools that have enabled in vivo, high-resolution imaging of the dynamic behaviors of cells in the spinal cord in mice. Surgical preparations that enable long-term optical access and robust stabilization of the spinal cord are now available. Labeling strategies that have been used in the spinal cord tend to follow those that have been used in the brain, and some recent advances in genetically-encoded labeling strategies remain to be capitalized on. The optical imaging methods used to date, including two photon excited fluorescence microscopy, are largely limited to imaging the superficial layers of the spinal cord by the optical scattering of the white matter. Finally, we show preliminary data that points to the use of higher-order nonlinear optical processes, such as three photon excited fluorescence, as a means to image deeper into the mouse spinal cord.
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Affiliation(s)
- Yu-Ting Cheng
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, USA; Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, USA
| | - Kawasi M Lett
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, USA
| | - Chris B Schaffer
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, USA.
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33
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Zheng B, Lorenzana AO, Ma L. Understanding the axonal response to injury by in vivo imaging in the mouse spinal cord: A tale of two branches. Exp Neurol 2019; 318:277-285. [PMID: 30986398 PMCID: PMC6588497 DOI: 10.1016/j.expneurol.2019.04.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 04/05/2019] [Accepted: 04/11/2019] [Indexed: 01/01/2023]
Abstract
Understanding the basic properties of how axons respond to injury in the mammalian central nervous system (CNS) is of fundamental value for developing strategies to promote neural repair. Axons possess complex morphologies with stereotypical branching patterns. However, current knowledge of the axonal response to injury gives little consideration to axonal branches, nor do strategies to promote axon regeneration. This article reviews evidence from in vivo spinal cord imaging that axonal branches markedly impact the degenerative and regenerative responses to injury. At a major bifurcation point, depending on whether one or both axonal branches are injured, neurons may choose either a more self-preservative response or a more dynamic response. The stabilizing effect of the spared branch may underlie a well-known divergence in neuronal responses to injury, and illustrates an example where in vivo spinal cord imaging reveals insights that are difficult to elucidate with conventional histological methods.
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Affiliation(s)
- Binhai Zheng
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, CA, USA; VA San Diego Healthcare System, San Diego, CA, USA.
| | - Ariana O Lorenzana
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Le Ma
- Department of Neuroscience, Jefferson Synaptic Biology Center, Vickie and Jack Farber Institute for Neuroscience, Sydney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
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34
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Abstract
Traumatic brain and spinal cord injuries cause permanent disability. Although progress has been made in understanding the cellular and molecular mechanisms underlying the pathophysiological changes that affect both structure and function after injury to the brain or spinal cord, there are currently no cures for either condition. This may change with the development and application of multi-layer omics, new sophisticated bioinformatics tools, and cutting-edge imaging techniques. Already, these technical advances, when combined, are revealing an unprecedented number of novel cellular and molecular targets that could be manipulated alone or in combination to repair the injured central nervous system with precision. In this review, we highlight recent advances in applying these new technologies to the study of axon regeneration and rebuilding of injured neural circuitry. We then discuss the challenges ahead to translate results produced by these technologies into clinical application to help improve the lives of individuals who have a brain or spinal cord injury.
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Affiliation(s)
- Andrea Tedeschi
- Department of Neuroscience and Discovery Themes Initiative, College of Medicine, Ohio State University, Columbus, Ohio, 43210, USA
| | - Phillip G Popovich
- Center for Brain and Spinal Cord Repair, Institute for Behavioral Medicine Research, Ohio State University, Columbus, Ohio, 43210, USA
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35
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Schaffran B, Hilton BJ, Bradke F. Imaging in vivo dynamics of sensory axon responses to CNS injury. Exp Neurol 2019; 317:110-118. [PMID: 30794766 DOI: 10.1016/j.expneurol.2019.02.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 02/13/2019] [Accepted: 02/17/2019] [Indexed: 01/25/2023]
Abstract
Axons in the adult mammalian brain and spinal cord fail to regenerate upon lesion. In vivo imaging serves as a tool to investigate the immediate response of axons to injury and how the same injured axons behave over time. Here, we describe the dynamic changes that injured sensory axons undergo and methods of imaging them in vivo. First, we explain how sensory axons in the dorsal column of the adult mouse spinal cord respond to axotomy. Then, we highlight practical considerations for implementing two-photon based in vivo imaging of these axons. Finally, we describe future directions for this technique, including the possibility of in vivo imaging of subcellular dynamics within the axon.
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Affiliation(s)
| | - Brett J Hilton
- German Center for Neurodegenerative Diseases, Bonn, Germany
| | - Frank Bradke
- German Center for Neurodegenerative Diseases, Bonn, Germany.
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36
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Li Z, Yao F, Cheng L, Cheng W, Qi L, Yu S, Zhang L, Zha X, Jing J. Low frequency pulsed electromagnetic field promotes the recovery of neurological function after spinal cord injury in rats. J Orthop Res 2019; 37:449-456. [PMID: 30378172 DOI: 10.1002/jor.24172] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 10/22/2018] [Indexed: 02/04/2023]
Abstract
Low frequency pulsed electromagnetic field (LFPEMF) has been shown to provide anti-inflammatory and antioxidative effects. However, there are no reports on whether LFPEMF can treat spinal cord injury (SCI) and its therapeutic mechanism. Therefore, this study was conducted to investigate whether LFPEMF can promote the recovery of neurological function after SCI in rats and its therapeutic mechanism. Basso-Beattie-Bresnahan (BBB) score and transcranial magnetic motor-evoked potentials (tcMMEPs) were recorded to assess the recovery of neurological function. Hematoxylin and eosin (HE) staining and luxol fast blue (LFB) staining were performed to assess the severity of SCI. Immunofluorescence (IF) staining and western blotting (WB) were performed to assess the differentiation of oligodendrocyte precursor cells (OPCs) into oligodendrocytes (OLs). Toluidine blue (TB) staining was performed to assess remyelination. WB and enzyme-linked immunosorbent assays (ELISA) were performed to assess the expression of neurotrophins and inflammatory factors. Our results showed that following stimulation by LFPEMF, there were significant improvements in BBB scores, tcMMEP amplitudes, the extent of the damage, and reduced demyelination in rats after SCI. The mature OLs, the number of well-myelinated fibers, and the myelin sheath thickness significantly increased in rats stimulated by LFPEMF after SCI. The expression of neurotrophins significantly increased, and the expression of inflammatory factors significantly decreased in rats stimulated by LFPEMF after SCI. Therefore, we suggest that LFPEMF can promote the recovery of neurological function in rats after SCI by improving the differentiation of OPCs into OLs and promoting remyelination, as well as by inhibiting inflammation and promoting neurotrophic effects. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:449-456, 2019.
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Affiliation(s)
- Ziyu Li
- Department of Orthopaedics, the Second Hospital of Anhui Medical University, Furong Road 678, Hefei, Anhui, 230601, China
| | - Fei Yao
- Department of Orthopaedics, the Second Hospital of Anhui Medical University, Furong Road 678, Hefei, Anhui, 230601, China
| | - Li Cheng
- Department of Orthopaedics, the Second Hospital of Anhui Medical University, Furong Road 678, Hefei, Anhui, 230601, China
| | - Wendan Cheng
- Department of Orthopaedics, the Second Hospital of Anhui Medical University, Furong Road 678, Hefei, Anhui, 230601, China
| | - Lei Qi
- Department of Orthopaedics, the Second Hospital of Anhui Medical University, Furong Road 678, Hefei, Anhui, 230601, China
| | - Shuisheng Yu
- Department of Orthopaedics, the Second Hospital of Anhui Medical University, Furong Road 678, Hefei, Anhui, 230601, China
| | - Liqian Zhang
- Department of Orthopaedics, the Second Hospital of Anhui Medical University, Furong Road 678, Hefei, Anhui, 230601, China
| | - Xiaowei Zha
- Department of Orthopaedics, the Second Hospital of Anhui Medical University, Furong Road 678, Hefei, Anhui, 230601, China
| | - Juehua Jing
- Department of Orthopaedics, the Second Hospital of Anhui Medical University, Furong Road 678, Hefei, Anhui, 230601, China
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Neumann B, Linton C, Giordano-Santini R, Hilliard MA. Axonal fusion: An alternative and efficient mechanism of nerve repair. Prog Neurobiol 2018; 173:88-101. [PMID: 30500382 DOI: 10.1016/j.pneurobio.2018.11.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 11/22/2018] [Accepted: 11/26/2018] [Indexed: 02/07/2023]
Abstract
Injuries to the nervous system can cause lifelong morbidity due to the disconnect that occurs between nerve cells and their cellular targets. Re-establishing these lost connections is the ultimate goal of endogenous regenerative mechanisms, as well as those induced by exogenous manipulations in a laboratory or clinical setting. Reconnection between severed neuronal fibers occurs spontaneously in some invertebrate species and can be induced in mammalian systems. This process, known as axonal fusion, represents a highly efficient means of repair after injury. Recent progress has greatly enhanced our understanding of the molecular control of axonal fusion, demonstrating that the machinery required for the engulfment of apoptotic cells is repurposed to mediate the reconnection between severed axon fragments, which are subsequently merged by fusogen proteins. Here, we review our current understanding of naturally occurring axonal fusion events, as well as those being ectopically produced with the aim of achieving better clinical outcomes.
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Affiliation(s)
- Brent Neumann
- Neuroscience Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne VIC 3800, Australia.
| | - Casey Linton
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Rosina Giordano-Santini
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Massimo A Hilliard
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
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Global Connectivity and Function of Descending Spinal Input Revealed by 3D Microscopy and Retrograde Transduction. J Neurosci 2018; 38:10566-10581. [PMID: 30341180 DOI: 10.1523/jneurosci.1196-18.2018] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 10/03/2018] [Accepted: 10/09/2018] [Indexed: 12/20/2022] Open
Abstract
The brain communicates with the spinal cord through numerous axon tracts that arise from discrete nuclei, transmit distinct functions, and often collateralize to facilitate the coordination of descending commands. This complexity presents a major challenge to interpreting functional outcomes from therapies that target supraspinal connectivity after injury or disease, while the wide distribution of supraspinal nuclei complicates the delivery of therapeutics. Here we harness retrograde viral vectors to overcome these challenges. We demonstrate that injection of AAV2-Retro to the cervical spinal cord of adult female mice results in highly efficient transduction of supraspinal populations throughout the brainstem, midbrain, and cortex. Some supraspinal populations, including corticospinal and rubrospinal neurons, were transduced with >90% efficiency, with robust transgene expression within 3 d of injection. In contrast, propriospinal and raphe spinal neurons showed much lower rates of retrograde transduction. Using tissue clearing and light-sheet microscopy we present detailed visualizations of descending axons tracts and create a mesoscopic projectome for the spinal cord. Moreover, chemogenetic silencing of supraspinal neurons with retrograde vectors resulted in complete and reversible forelimb paralysis, illustrating effective modulation of supraspinal function. Retrograde vectors were also highly efficient when injected after spinal injury, highlighting therapeutic potential. These data provide a global view of supraspinal connectivity and illustrate the potential of retrograde vectors to parse the functional contributions of supraspinal inputs.SIGNIFICANCE STATEMENT The complexity of descending inputs to the spinal cord presents a major challenge in efforts deliver therapeutics to widespread supraspinal systems, and to interpret their functional effects. Here we demonstrate highly effective gene delivery to diverse supraspinal nuclei using a retrograde viral approach and combine it with tissue clearing and 3D microscopy to map the descending projectome from brain to spinal cord. These data highlight newly developed retrograde viruses as therapeutic and research tools, while offering new insights into supraspinal connectivity.
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Curcio M, Bradke F. Axon Regeneration in the Central Nervous System: Facing the Challenges from the Inside. Annu Rev Cell Dev Biol 2018; 34:495-521. [DOI: 10.1146/annurev-cellbio-100617-062508] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
After an injury in the adult mammalian central nervous system (CNS), lesioned axons fail to regenerate. This failure to regenerate contrasts with axons’ remarkable potential to grow during embryonic development and after an injury in the peripheral nervous system (PNS). Several intracellular mechanisms—including cytoskeletal dynamics, axonal transport and trafficking, signaling and transcription of regenerative programs, and epigenetic modifications—control axon regeneration. In this review, we describe how manipulation of intrinsic mechanisms elicits a regenerative response in different organisms and how strategies are implemented to form the basis of a future regenerative treatment after CNS injury.
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Affiliation(s)
- Michele Curcio
- Laboratory for Axon Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), 53127 Bonn, Germany;,
| | - Frank Bradke
- Laboratory for Axon Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), 53127 Bonn, Germany;,
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40
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Attwell CL, van Zwieten M, Verhaagen J, Mason MRJ. The Dorsal Column Lesion Model of Spinal Cord Injury and Its Use in Deciphering the Neuron-Intrinsic Injury Response. Dev Neurobiol 2018; 78:926-951. [PMID: 29717546 PMCID: PMC6221129 DOI: 10.1002/dneu.22601] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 04/03/2018] [Accepted: 04/05/2018] [Indexed: 12/13/2022]
Abstract
The neuron‐intrinsic response to axonal injury differs markedly between neurons of the peripheral and central nervous system. Following a peripheral lesion, a robust axonal growth program is initiated, whereas neurons of the central nervous system do not mount an effective regenerative response. Increasing the neuron‐intrinsic regenerative response would therefore be one way to promote axonal regeneration in the injured central nervous system. The large‐diameter sensory neurons located in the dorsal root ganglia are pseudo‐unipolar neurons that project one axon branch into the spinal cord, and, via the dorsal column to the brain stem, and a peripheral process to the muscles and skin. Dorsal root ganglion neurons are ideally suited to study the neuron‐intrinsic injury response because they exhibit a successful growth response following peripheral axotomy, while they fail to do so after a lesion of the central branch in the dorsal column. The dorsal column injury model allows the neuron‐intrinsic regeneration response to be studied in the context of a spinal cord injury. Here we will discuss the advantages and disadvantages of this model. We describe the surgical methods used to implement a lesion of the ascending fibers, the anatomy of the sensory afferent pathways and anatomical, electrophysiological, and behavioral techniques to quantify regeneration and functional recovery. Subsequently we review the results of experimental interventions in the dorsal column lesion model, with an emphasis on the molecular mechanisms that govern the neuron‐intrinsic injury response and manipulations of these after central axotomy. Finally, we highlight a number of recent advances that will have an impact on the design of future studies in this spinal cord injury model, including the continued development of adeno‐associated viral vectors likely to improve the genetic manipulation of dorsal root ganglion neurons and the use of tissue clearing techniques enabling 3D reconstruction of regenerating axon tracts. © 2018 The Authors. Developmental Neurobiology Published by Wiley Periodicals, Inc. Develop Neurobiol 00: 000–000, 2018
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Affiliation(s)
- Callan L Attwell
- Laboratory for Regeneration of Sensorimotor Systems, Netherlands Institute for Neuroscience, an Institute of the Royal Netherlands Academy of Arts and Science, Meibergdreef 47, Amsterdam, 1105BA, The Netherlands
| | - Mike van Zwieten
- Laboratory for Regeneration of Sensorimotor Systems, Netherlands Institute for Neuroscience, an Institute of the Royal Netherlands Academy of Arts and Science, Meibergdreef 47, Amsterdam, 1105BA, The Netherlands
| | - Joost Verhaagen
- Laboratory for Regeneration of Sensorimotor Systems, Netherlands Institute for Neuroscience, an Institute of the Royal Netherlands Academy of Arts and Science, Meibergdreef 47, Amsterdam, 1105BA, The Netherlands.,Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, De Boelelaan 1085, Amsterdam, 1081HV, The Netherlands
| | - Matthew R J Mason
- Laboratory for Regeneration of Sensorimotor Systems, Netherlands Institute for Neuroscience, an Institute of the Royal Netherlands Academy of Arts and Science, Meibergdreef 47, Amsterdam, 1105BA, The Netherlands
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41
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White MD, Zhao ZW, Plachta N. In Vivo Imaging of Single Mammalian Cells in Development and Disease. Trends Mol Med 2018; 24:278-293. [PMID: 29439932 DOI: 10.1016/j.molmed.2018.01.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 01/05/2018] [Accepted: 01/14/2018] [Indexed: 12/14/2022]
Abstract
Live imaging has transformed biomedical sciences by enabling visualization and analysis of dynamic cellular processes as they occur in their native contexts. Here, we review key recent efforts applying in vivo optical imaging with single-cell resolution to mammalian systems ranging from embryos to adult tissues and organs. We highlight insights into active processes regulating cell fate and morphogenesis during embryonic development, how neuronal circuitry and non-neuronal cell types contribute to neurological functions, and how novel imaging-based approaches enable the dissection of neurological disorders and cancer with high spatio-temporal resolution. The convergence of technical advancements in accessing, visualizing, and manipulating individual cells provides an unprecedented lens to probe mammalian cellular dynamics in vivo in both physiological and pathological states.
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Affiliation(s)
- Melanie D White
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore; These authors contributed equally to this work
| | - Ziqing W Zhao
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore; These authors contributed equally to this work
| | - Nicolas Plachta
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore.
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Li J, Wang Q, Wang H, Wu Y, Yin J, Chen J, Zheng Z, Jiang T, Xie L, Wu F, Zhang H, Li X, Xu H, Xiao J. Lentivirus Mediating FGF13 Enhances Axon Regeneration after Spinal Cord Injury by Stabilizing Microtubule and Improving Mitochondrial Function. J Neurotrauma 2017; 35:548-559. [PMID: 28922963 DOI: 10.1089/neu.2017.5205] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Fibroblast growth factor 13 (FGF13), a nonsecretory protein of the FGF family, plays a crucial role in developing cortical neurons by stabilizing the microtubule. In previous studies, we showed that regulation of microtubule dynamics was instrumental for both growth cone initiation and for promoting regrowth of injured axon. However, the expression and effect of FGF13 in spinal cord or after spinal cord injury (SCI) remains undefined. Here, we demonstrated a role of FGF13 in regulating microtubule dynamics and in enhancing axon regeneration after SCI. Administration of FGF13 not only promoted neuronal polarization, axon formation, and growth cone initiation in vitro, but it also facilitated functional recovery following SCI. In addition, we found that upregulation of FGF13 in primary cortical neurons was accompanied by enhanced mitochondrial function, which is essential for axon regeneration. Our study has defined a novel mechanism underlying the beneficial effect of FGF13 on axon regeneration, pointing out that FGF13 may serve as a potential candidate for treating SCI or other central nervous system (CNS) injury.
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Affiliation(s)
- Jiawei Li
- 1 Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University , Wenzhou, Zhejiang, China .,2 Molecular Pharmacology Research Center, School of Pharmaceutical Science, Wenzhou Medical University , Wenzhou, Zhejiang, China
| | - Qingqing Wang
- 1 Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University , Wenzhou, Zhejiang, China .,2 Molecular Pharmacology Research Center, School of Pharmaceutical Science, Wenzhou Medical University , Wenzhou, Zhejiang, China
| | - Haoli Wang
- 1 Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University , Wenzhou, Zhejiang, China .,2 Molecular Pharmacology Research Center, School of Pharmaceutical Science, Wenzhou Medical University , Wenzhou, Zhejiang, China
| | - Yanqing Wu
- 3 The Institute of Life Sciences, Wenzhou University , Wenzhou, Zhejiang, China
| | - Jiayu Yin
- 2 Molecular Pharmacology Research Center, School of Pharmaceutical Science, Wenzhou Medical University , Wenzhou, Zhejiang, China
| | - Jian Chen
- 1 Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University , Wenzhou, Zhejiang, China .,2 Molecular Pharmacology Research Center, School of Pharmaceutical Science, Wenzhou Medical University , Wenzhou, Zhejiang, China
| | - Zengming Zheng
- 1 Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University , Wenzhou, Zhejiang, China .,2 Molecular Pharmacology Research Center, School of Pharmaceutical Science, Wenzhou Medical University , Wenzhou, Zhejiang, China
| | - Ting Jiang
- 2 Molecular Pharmacology Research Center, School of Pharmaceutical Science, Wenzhou Medical University , Wenzhou, Zhejiang, China
| | - Ling Xie
- 2 Molecular Pharmacology Research Center, School of Pharmaceutical Science, Wenzhou Medical University , Wenzhou, Zhejiang, China
| | - Fenzan Wu
- 4 Department of Neurosurgery, Cixi People's Hospital, Wenzhou Medical University , Ningbo, Zhejiang, China
| | - Hongyu Zhang
- 2 Molecular Pharmacology Research Center, School of Pharmaceutical Science, Wenzhou Medical University , Wenzhou, Zhejiang, China
| | - Xiaokun Li
- 3 The Institute of Life Sciences, Wenzhou University , Wenzhou, Zhejiang, China
| | - Huazi Xu
- 1 Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University , Wenzhou, Zhejiang, China
| | - Jian Xiao
- 1 Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University , Wenzhou, Zhejiang, China .,2 Molecular Pharmacology Research Center, School of Pharmaceutical Science, Wenzhou Medical University , Wenzhou, Zhejiang, China
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Huang R, Chen M, Yang L, Wagle M, Guo S, Hu B. MicroRNA-133b Negatively Regulates Zebrafish Single Mauthner-Cell Axon Regeneration through Targeting tppp3 in Vivo. Front Mol Neurosci 2017; 10:375. [PMID: 29209165 PMCID: PMC5702462 DOI: 10.3389/fnmol.2017.00375] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 10/27/2017] [Indexed: 12/30/2022] Open
Abstract
Axon regeneration, fundamental to nerve repair, and functional recovery, relies on rapid changes in gene expression attributable to microRNA (miRNA) regulation. MiR-133b has been proved to play an important role in different organ regeneration in zebrafish, but its role in regulating axon regeneration in vivo is still controversial. Here, combining single-cell electroporation with a vector-based miRNA-expression system, we have modulated the expression of miR-133b in Mauthner-cells (M-cells) at the single-cell level in zebrafish. Through in vivo imaging, we show that overexpression of miR-133b inhibits axon regeneration, whereas down-regulation of miR-133b, promotes axon outgrowth. We further show that miR-133b regulates axon regeneration by directly targeting a novel regeneration-associated gene, tppp3, which belongs to Tubulin polymerization-promoting protein family. Gain or loss-of-function of tppp3 experiments indicated that tppp3 was a novel gene that could promote axon regeneration. In addition, we observed a reduction of mitochondrial motility, which have been identified to have a positive correlation with axon regeneration, in miR-133b overexpressed M-cells. Taken together, our work provides a novel way to study the role of miRNAs in individual cell and establishes a critical cell autonomous role of miR-133b in zebrafish M-cell axon regeneration. We propose that up-regulation of the newly founded regeneration-associated gene tppp3 may enhance axonal regeneration.
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Affiliation(s)
- Rongchen Huang
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Min Chen
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Leiqing Yang
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Mahendra Wagle
- Programs in Human Genetics and Biological Sciences, Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, United States
| | - Su Guo
- Programs in Human Genetics and Biological Sciences, Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, United States
| | - Bing Hu
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, School of Life Sciences, University of Science and Technology of China, Hefei, China
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44
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In Vivo Imaging of CNS Injury and Disease. J Neurosci 2017; 37:10808-10816. [PMID: 29118209 DOI: 10.1523/jneurosci.1826-17.2017] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 10/02/2017] [Accepted: 10/03/2017] [Indexed: 02/06/2023] Open
Abstract
In vivo optical imaging has emerged as a powerful tool with which to study cellular responses to injury and disease in the mammalian CNS. Important new insights have emerged regarding axonal degeneration and regeneration, glial responses and neuroinflammation, changes in the neurovascular unit, and, more recently, neural transplantations. Accompanying a 2017 SfN Mini-Symposium, here, we discuss selected recent advances in understanding the neuronal, glial, and other cellular responses to CNS injury and disease with in vivo imaging of the rodent brain or spinal cord. We anticipate that in vivo optical imaging will continue to be at the forefront of breakthrough discoveries of fundamental mechanisms and therapies for CNS injury and disease.
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45
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Abstract
In this issue of Neuron, Tedeschi et al. (2016) describe the voltage-gated calcium channel subunit alpha2delta2 as a developmental switch from axon elongation to synapse formation and transmission that doubles as a suppressor of axon regeneration, providing a molecular clue for the synaptic stabilization hypothesis of CNS regeneration failure.
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Affiliation(s)
- Jessica M Meves
- Neurosciences Graduate Program and Department of Neurosciences, University of California San Diego, School of Medicine, 9500 Gilman Drive, MC 0691, La Jolla, CA 92093, USA
| | - Binhai Zheng
- Neurosciences Graduate Program and Department of Neurosciences, University of California San Diego, School of Medicine, 9500 Gilman Drive, MC 0691, La Jolla, CA 92093, USA.
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46
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Hilton BJ, Bradke F. Can injured adult CNS axons regenerate by recapitulating development? Development 2017; 144:3417-3429. [PMID: 28974639 DOI: 10.1242/dev.148312] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In the adult mammalian central nervous system (CNS), neurons typically fail to regenerate their axons after injury. During development, by contrast, neurons extend axons effectively. A variety of intracellular mechanisms mediate this difference, including changes in gene expression, the ability to form a growth cone, differences in mitochondrial function/axonal transport and the efficacy of synaptic transmission. In turn, these intracellular processes are linked to extracellular differences between the developing and adult CNS. During development, the extracellular environment directs axon growth and circuit formation. In adulthood, by contrast, extracellular factors, such as myelin and the extracellular matrix, restrict axon growth. Here, we discuss whether the reactivation of developmental processes can elicit axon regeneration in the injured CNS.
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Affiliation(s)
- Brett J Hilton
- Laboratory for Axon Growth and Regeneration, German Centre for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
| | - Frank Bradke
- Laboratory for Axon Growth and Regeneration, German Centre for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
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47
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Abstract
Although much is known about the regenerative capacity of retinal ganglion cells, very significant barriers remain in our ability to restore visual function following traumatic injury or disease-induced degeneration. Here we summarize our current understanding of the factors regulating axon guidance and target engagement in regenerating axons, and review the state of the field of neural regeneration, focusing on the visual system and highlighting studies using other model systems that can inform analysis of visual system regeneration. This overview is motivated by a Society for Neuroscience Satellite meeting, "Reconnecting Neurons in the Visual System," held in October 2015 sponsored by the National Eye Institute as part of their "Audacious Goals Initiative" and co-organized by Carol Mason (Columbia University) and Michael Crair (Yale University). The collective wisdom of the conference participants pointed to important gaps in our knowledge and barriers to progress in promoting the restoration of visual system function. This article is thus a summary of our existing understanding of visual system regeneration and provides a blueprint for future progress in the field.
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48
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Optic nerve regeneration in mammals: Regenerated or spared axons? Exp Neurol 2017; 296:83-88. [PMID: 28716559 DOI: 10.1016/j.expneurol.2017.07.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 07/09/2017] [Accepted: 07/13/2017] [Indexed: 12/14/2022]
Abstract
Intraorbital optic nerve crush in rodents is widely used as a model to study axon regeneration in the adult mammalian central nervous system. Recent studies using appropriate genetic manipulations have revealed remarkable abilities of mature retinal ganglion cell (RGC) axons to regenerate after optic nerve injury, with some studies demonstrating that axons can then go on to re-innervate a number of central visual targets with partial functional restoration. However, one confounding factor inherent to optic nerve crush injury is the potential incompleteness of the initial lesion, leaving spared axons that later on could erroneously be interpreted as regenerating distal to the injury site. Careful examination of axonal projection pattern and morphology may facilitate separating spared from regenerating RGC axons. Here we discuss morphological criteria and strategies that may be used to differentiate spared versus regenerated axons in the injured mammalian optic nerve.
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49
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Xu Y, Chen M, Hu B, Huang R, Hu B. In vivo Imaging of Mitochondrial Transport in Single-Axon Regeneration of Zebrafish Mauthner Cells. Front Cell Neurosci 2017; 11:4. [PMID: 28174522 PMCID: PMC5258718 DOI: 10.3389/fncel.2017.00004] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 01/09/2017] [Indexed: 12/17/2022] Open
Abstract
Mitochondrial transport is essential for neuronal function, but the evidence of connections between mitochondrial transport and axon regeneration in the central nervous system (CNS) of living vertebrates remains limited. Here, we developed a novel model to explore mitochondrial transport in a single Mauthner axon (M axon) of zebrafish with non-invasive in vivo imaging. To confirm the feasibility of using this model, we treated labeled zebrafish with nocodazole and demonstrated that it could disrupt mitochondrial transport. We also used two-photon laser axotomy to precisely axotomize M axons and simultaneously recorded their regeneration and the process of mitochondrial transport in living zebrafish larvae. The findings showed that the injured axons with stronger regenerative capability maintain greater mitochondrial motility. Furthermore, to stimulate axon regeneration, treatment with dibutyryl cyclic adenosine monophosphate (db-cAMP) could also augment mitochondrial motility. Taken together, our results provide new evidence that mitochondrial motility is positively correlated with axon regeneration in the living vertebrate CNS. This promising model will be useful for further studies on the interaction between axon regeneration and mitochondrial dynamics, using various genetic and pharmacological techniques.
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Affiliation(s)
- Yang Xu
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China Hefei, China
| | - Min Chen
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China Hefei, China
| | - Bingbing Hu
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China Hefei, China
| | - Rongchen Huang
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China Hefei, China
| | - Bing Hu
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China Hefei, China
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50
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Learning to swim, again: Axon regeneration in fish. Exp Neurol 2017; 287:318-330. [DOI: 10.1016/j.expneurol.2016.02.022] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 02/25/2016] [Accepted: 02/27/2016] [Indexed: 01/10/2023]
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