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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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2
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Harmon JN, Hyde JE, Jensen DE, D'cessare EC, Odarenko AA, Bruce MF, Khaing ZZ. Quantifying injury expansion in the cervical spinal cord with intravital ultrafast contrast-enhanced ultrasound imaging. Exp Neurol 2024; 374:114681. [PMID: 38199511 PMCID: PMC10922898 DOI: 10.1016/j.expneurol.2024.114681] [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: 10/30/2023] [Revised: 12/08/2023] [Accepted: 01/02/2024] [Indexed: 01/12/2024]
Abstract
Spinal cord injury is characterized by hemodynamic disruption at the injury epicenter and hypoperfusion in the penumbra, resulting in progressive ischemia and cell death. This degenerative secondary injury process has been well-described, though mostly using ex vivo or depth-limited optical imaging techniques. Intravital contrast-enhanced ultrasound enables longitudinal, quantitative evaluation of anatomical and hemodynamic changes in vivo through the entire spinal parenchyma. Here, we used ultrasound imaging to visualize and quantify subacute injury expansion (through 72 h post-injury) in a rodent cervical contusion model. Significant intraparenchymal hematoma expansion was observed through 72 h post-injury (1.86 ± 0.17-fold change from acute, p < 0.05), while the volume of the ischemic deficit largely increased within 24 h post-injury (2.24 ± 0.27-fold, p < 0.05). Histology corroborated these findings; increased apoptosis, tissue and vessel loss, and sustained tissue hypoxia were observed at 72 h post-injury. Vascular resistance was significantly elevated in the remaining perfused tissue, likely due in part to deformation of the central sulcal artery nearest to the lesion site. In conjunction, substantial hyperemia was observed in all perilesional areas examined except the ipsilesional gray matter. This study demonstrates the utility of longitudinal ultrasound imaging as a quantitative tool for tracking injury progression in vivo.
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Affiliation(s)
- Jennifer N Harmon
- Department of Neurological Surgery, University of Washington, 1959 NE Pacific St., Seattle, WA, USA.
| | - Jeffrey E Hyde
- Department of Neurological Surgery, University of Washington, 1959 NE Pacific St., Seattle, WA, USA.
| | - Dylan E Jensen
- Department of Neurological Surgery, University of Washington, 1959 NE Pacific St., Seattle, WA, USA.
| | - Emma C D'cessare
- Department of Neurological Surgery, University of Washington, 1959 NE Pacific St., Seattle, WA, USA.
| | - Anton A Odarenko
- Department of Neurological Surgery, University of Washington, 1959 NE Pacific St., Seattle, WA, USA.
| | - Matthew F Bruce
- Applied Physics Laboratory, University of Washington, Seattle, WA, USA.
| | - Zin Z Khaing
- Department of Neurological Surgery, University of Washington, 1959 NE Pacific St., Seattle, WA, USA.
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3
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Celinskis D, Black CJ, Murphy J, Barrios-Anderson A, Friedman NG, Shaner NC, Saab CY, Gomez-Ramirez M, Borton DA, Moore CI. Toward a brighter constellation: multiorgan neuroimaging of neural and vascular dynamics in the spinal cord and brain. NEUROPHOTONICS 2024; 11:024209. [PMID: 38725801 PMCID: PMC11079446 DOI: 10.1117/1.nph.11.2.024209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 03/18/2024] [Accepted: 03/19/2024] [Indexed: 05/12/2024]
Abstract
Significance Pain comprises a complex interaction between motor action and somatosensation that is dependent on dynamic interactions between the brain and spinal cord. This makes understanding pain particularly challenging as it involves rich interactions between many circuits (e.g., neural and vascular) and signaling cascades throughout the body. As such, experimentation on a single region may lead to an incomplete and potentially incorrect understanding of crucial underlying mechanisms. Aim We aimed to develop and validate tools to enable detailed and extended observation of neural and vascular activity in the brain and spinal cord. The first key set of innovations was targeted to developing novel imaging hardware that addresses the many challenges of multisite imaging. The second key set of innovations was targeted to enabling bioluminescent (BL) imaging, as this approach can address limitations of fluorescent microscopy including photobleaching, phototoxicity, and decreased resolution due to scattering of excitation signals. Approach We designed 3D-printed brain and spinal cord implants to enable effective surgical implantations and optical access with wearable miniscopes or an open window (e.g., for one- or two-photon microscopy or optogenetic stimulation). We also tested the viability for BL imaging and developed a novel modified miniscope optimized for these signals (BLmini). Results We describe "universal" implants for acute and chronic simultaneous brain-spinal cord imaging and optical stimulation. We further describe successful imaging of BL signals in both foci and a new miniscope, the "BLmini," which has reduced weight, cost, and form-factor relative to standard wearable miniscopes. Conclusions The combination of 3D-printed implants, advanced imaging tools, and bioluminescence imaging techniques offers a coalition of methods for understanding spinal cord-brain interactions. Our work has the potential for use in future research into neuropathic pain and other sensory disorders and motor behavior.
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Affiliation(s)
- Dmitrijs Celinskis
- Carney Institute for Brain Science, Providence, Rhode Island, United States
| | | | - Jeremy Murphy
- Carney Institute for Brain Science, Providence, Rhode Island, United States
| | | | - Nina G. Friedman
- Carney Institute for Brain Science, Providence, Rhode Island, United States
| | - Nathan C. Shaner
- University of California San Diego, School of Medicine, La Jolla, California, United States
| | - Carl Y. Saab
- Cleveland Clinic Lerner Research Institute, Neurological Institute, Department of Biomedical Engineering, Cleveland, Ohio, United States
| | - Manuel Gomez-Ramirez
- University of Rochester, School of Arts and Sciences, Rochester, New York, United States
| | - David A. Borton
- Carney Institute for Brain Science, Providence, Rhode Island, United States
- Brown University, School of Engineering, Providence, Rhode Island, United States
- Center for Neurorestoration and Neurotechnology, Providence VA Medical Center, Providence, Rhode Island, United States
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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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Harmon JN, Chandran P, Chandrasekaran A, Hyde JE, Hernandez GJ, Reed MJ, Bruce MF, Khaing ZZ. Contrast-enhanced ultrasound imaging detects anatomical and functional changes in rat cervical spine microvasculature with normal aging. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.12.584672. [PMID: 38559128 PMCID: PMC10980054 DOI: 10.1101/2024.03.12.584672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Normal aging is associated with significant deleterious cerebrovascular changes; these have been implicated in disease pathogenesis and increased susceptibility to ischemic injury. While these changes are well documented in the brain, few studies have been conducted in the spinal cord. Here, we utilize specialized contrast-enhanced ultrasound (CEUS) imaging to investigate age-related changes in cervical spinal vascular anatomy and hemodynamics in male Fisher 344 rats, a common strain in aging research. Aged rats (24-26 mo., N=6) exhibited significant tortuosity in the anterior spinal artery and elevated vascular resistance compared to adults (4-6 mo., N=6; tortuosity index 2.20±0.15 vs 4.74±0.45, p<0.05). Baseline blood volume was lower in both larger vessels and the microcirculation in the aged cohort, specifically in white matter (4.44e14±1.37e13 vs 3.66e14±2.64e13 CEUS bolus AUC, p<0.05). To elucidate functional differences, animals were exposed to a hypoxia challenge; whereas adult rats exhibited significant functional hyperemia in both gray and white matter (GM: 1.13±0.10-fold change from normoxia, p<0.05; WM: 1.16±0.13, p<0.05), aged rats showed no response. Immunohistochemistry revealed reduced pericyte coverage and activated microglia behavior in aged rats, which may partially explain the lack of vascular response. This study provides the first in vivo description of age-related hemodynamic differences in the cervical spinal cord.
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Affiliation(s)
- Jennifer N. Harmon
- Department of Neurological Surgery, University of Washington, 1959 NE Pacific St., Seattle, WA, USA
| | - Preeja Chandran
- Department of Neurological Surgery, University of Washington, 1959 NE Pacific St., Seattle, WA, USA
| | | | - Jeffrey E. Hyde
- Department of Neurological Surgery, University of Washington, 1959 NE Pacific St., Seattle, WA, USA
| | - Gustavo J. Hernandez
- Department of Neurological Surgery, University of Washington, 1959 NE Pacific St., Seattle, WA, USA
| | - May J. Reed
- Department of Gerontology and Geriatric Medicine, University of Washington, Seattle, WA, USA
| | - Matthew F. Bruce
- Applied Physics Laboratory, University of Washington, Seattle, WA, USA
| | - Zin Z. Khaing
- Department of Neurological Surgery, University of Washington, 1959 NE Pacific St., Seattle, WA, USA
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6
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Celinskis D, Black CJ, Murphy J, Barrios-Anderson A, Friedman N, Shaner NC, Saab C, Gomez-Ramirez M, Lipscombe D, Borton DA, Moore CI. Towards a Brighter Constellation: Multi-Organ Neuroimaging of Neural and Vascular Dynamics in the Spinal Cord and Brain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.25.573323. [PMID: 38234789 PMCID: PMC10793404 DOI: 10.1101/2023.12.25.573323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
Significance Pain is comprised of a complex interaction between motor action and somatosensation that is dependent on dynamic interactions between the brain and spinal cord. This makes understanding pain particularly challenging as it involves rich interactions between many circuits (e.g., neural and vascular) and signaling cascades throughout the body. As such, experimentation on a single region may lead to an incomplete and potentially incorrect understanding of crucial underlying mechanisms. Aim Here, we aimed to develop and validate new tools to enable detailed and extended observation of neural and vascular activity in the brain and spinal cord. The first key set of innovations were targeted to developing novel imaging hardware that addresses the many challenges of multi-site imaging. The second key set of innovations were targeted to enabling bioluminescent imaging, as this approach can address limitations of fluorescent microscopy including photobleaching, phototoxicity and decreased resolution due to scattering of excitation signals. Approach We designed 3D-printed brain and spinal cord implants to enable effective surgical implantations and optical access with wearable miniscopes or an open window (e.g., for one- or two-photon microscopy or optogenetic stimulation). We also tested the viability for bioluminescent imaging, and developed a novel modified miniscope optimized for these signals (BLmini). Results Here, we describe novel 'universal' implants for acute and chronic simultaneous brain-spinal cord imaging and optical stimulation. We further describe successful imaging of bioluminescent signals in both foci, and a new miniscope, the 'BLmini,' which has reduced weight, cost and form-factor relative to standard wearable miniscopes. Conclusions The combination of 3D printed implants, advanced imaging tools, and bioluminescence imaging techniques offers a new coalition of methods for understanding spinal cord-brain interactions. This work has the potential for use in future research into neuropathic pain and other sensory disorders and motor behavior.
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Affiliation(s)
| | | | - Jeremy Murphy
- Carney Institute for Brain Science, Providence, RI, USA
| | | | - Nina Friedman
- Carney Institute for Brain Science, Providence, RI, USA
| | - Nathan C. Shaner
- University of California San Diego School of Medicine, La Jolla, CA, USA
| | - Carl Saab
- Cleveland Clinic Lerner Research Institute, Department of Biomedical Engineering and Neurological Institute, Cleveland, OH, USA
| | | | | | - David A. Borton
- Carney Institute for Brain Science, Providence, RI, USA
- School of Engineering, Brown University, RI, USA
- Center for Neurorestoration and Neurotechnology, Providence VA Medical Center, RI, USA
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7
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Ahanonu B, Crowther A, Kania A, Casillas MR, Basbaum A. Long-term optical imaging of the spinal cord in awake, behaving animals. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.22.541477. [PMID: 37292913 PMCID: PMC10245895 DOI: 10.1101/2023.05.22.541477] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Advances in optical imaging approaches and fluorescent biosensors have enabled an understanding of the spatiotemporal and long-term neural dynamics in the brain of awake animals. However, methodological difficulties and the persistence of post-laminectomy fibrosis have greatly limited similar advances in the spinal cord. To overcome these technical obstacles, we combined in vivo application of fluoropolymer membranes that inhibit fibrosis; a redesigned, cost-effective implantable spinal imaging chamber; and improved motion correction methods that together permit imaging of the spinal cord in awake, behaving mice, for months to over a year. We also demonstrate a robust ability to monitor axons, identify a spinal cord somatotopic map, conduct Ca2+ imaging of neural dynamics in behaving animals responding to pain-provoking stimuli, and observe persistent microglial changes after nerve injury. The ability to couple neural activity and behavior at the spinal cord level will drive insights not previously possible at a key location for somatosensory transmission to the brain.
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Affiliation(s)
- Biafra Ahanonu
- Department of Anatomy, University of California, San Francisco, San Francisco, CA 94158, USA
- These authors contributed equally
| | - Andrew Crowther
- Department of Anatomy, University of California, San Francisco, San Francisco, CA 94158, USA
- These authors contributed equally
| | - Artur Kania
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, H2W 1R7, Canada
- Department of Cell Biology and Anatomy, and Division of Experimental Medicine, McGill University, Montréal, QC, H3A 2B2, Canada
| | - Mariela Rosa Casillas
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Allan Basbaum
- Department of Anatomy, University of California, San Francisco, San Francisco, CA 94158, USA
- Lead Contact
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8
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Lobo MEDV, Bates DO, Arkill KP, Hulse RP. Measurement of solute permeability in the mouse spinal cord. J Neurosci Methods 2023; 393:109880. [PMID: 37178727 DOI: 10.1016/j.jneumeth.2023.109880] [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: 02/27/2023] [Revised: 05/01/2023] [Accepted: 05/08/2023] [Indexed: 05/15/2023]
Abstract
BACKGROUND Sensory perception and motor dexterity is coordinated by the spinal cord, which remains effective due to maintenance of neuronal homeostasis. This is stringently controlled by the blood spinal cord barrier. Therefore, the function of the spinal cord is susceptible to alterations in the microvessel integrity (e.g. vascular leakage) and/or perfusion (e.g. changes in blood flow). NEW METHOD Spinal cord solute permeability was measured in anaesthetised mice. The lumbar spinal cord vertebra were stabilised and a coverslip secured to allow fluorescent tracers of vascular function and anatomy to be visualised in the vascular network. Fluorescence microscopy allowed real time measurements of vascular leakage and capillary perfusion within the spinal cord. RESULTS Capillaries were identified through fluorescent labelling of the endothelial luminal glycocalyx (wheat germ agglutin 555). Real time estimation of vascular permeability through visualisation of sodium fluorescein transport was recorded from identified microvessels in the lumbar dorsal horn of the spinal cord. COMPARISON WITH EXISTING METHOD(S) Current approaches have used histological and/or tracer based in-vivo assays alongside cell culture to determine endothelium integrity and/or function. These only provide a snapshot of the developing vasculopathy, restricting the understanding of physiological function or disease progression over time. CONCLUSIONS These techniques allow for direct visualisation of cellular and/or mechanistic influences upon vascular function and integrity, which can be applied to rodent models including disease, transgenic and/or viral approaches. This combination of attributes allows for real time understanding of the function of the vascular network within the spinal cord.
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Affiliation(s)
- Marlene Elisa Da Vitoria Lobo
- Division of Cancer and Stem Cells, School of Medicine, Biodiscovery Institute, University of Nottingham, Nottingham NG7 2UH
| | - David O Bates
- Division of Cancer and Stem Cells, School of Medicine, Biodiscovery Institute, University of Nottingham, Nottingham NG7 2UH; Centre of Membrane and Protein and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
| | - Kenton P Arkill
- Division of Cancer and Stem Cells, School of Medicine, Biodiscovery Institute, University of Nottingham, Nottingham NG7 2UH
| | - Richard Philip Hulse
- School of Science and Technology, Nottingham Trent University, Nottingham, NG11 8NS.
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9
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Shekhtmeyster P, Carey EM, Duarte D, Ngo A, Gao G, Nelson NA, Clark CL, Nimmerjahn A. Multiplex translaminar imaging in the spinal cord of behaving mice. Nat Commun 2023; 14:1427. [PMID: 36944637 PMCID: PMC10030868 DOI: 10.1038/s41467-023-36959-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 02/24/2023] [Indexed: 03/23/2023] Open
Abstract
While the spinal cord is known to play critical roles in sensorimotor processing, including pain-related signaling, corresponding activity patterns in genetically defined cell types across spinal laminae have remained challenging to investigate. Calcium imaging has enabled cellular activity measurements in behaving rodents but is currently limited to superficial regions. Here, using chronically implanted microprisms, we imaged sensory and motor-evoked activity in regions and at speeds inaccessible by other high-resolution imaging techniques. To enable translaminar imaging in freely behaving animals through implanted microprisms, we additionally developed wearable microscopes with custom-compound microlenses. This system addresses multiple challenges of previous wearable microscopes, including their limited working distance, resolution, contrast, and achromatic range. Using this system, we show that dorsal horn astrocytes in behaving mice show sensorimotor program-dependent and lamina-specific calcium excitation. Additionally, we show that tachykinin precursor 1 (Tac1)-expressing neurons exhibit translaminar activity to acute mechanical pain but not locomotion.
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Affiliation(s)
- Pavel Shekhtmeyster
- Waitt Advanced Biophotonics Center, The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
- Electrical and Computer Engineering Graduate Program, University of California, San Diego, La Jolla, CA, 92037, USA
| | - Erin M Carey
- Waitt Advanced Biophotonics Center, The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
| | - Daniela Duarte
- Waitt Advanced Biophotonics Center, The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
| | - Alexander Ngo
- Waitt Advanced Biophotonics Center, The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
| | - Grace Gao
- Waitt Advanced Biophotonics Center, The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
| | - Nicholas A Nelson
- Waitt Advanced Biophotonics Center, The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
- Biological Sciences Graduate Program, University of California, San Diego, La Jolla, CA, 92037, USA
| | - Charles L Clark
- Waitt Advanced Biophotonics Center, The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
| | - Axel Nimmerjahn
- Waitt Advanced Biophotonics Center, The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA.
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10
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Romero G, Park J, Koehler F, Pralle A, Anikeeva P. Modulating cell signalling in vivo with magnetic nanotransducers. NATURE REVIEWS. METHODS PRIMERS 2022; 2:92. [PMID: 38111858 PMCID: PMC10727510 DOI: 10.1038/s43586-022-00170-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 09/15/2022] [Indexed: 12/20/2023]
Abstract
Weak magnetic fields offer nearly lossless transmission of signals within biological tissue. Magnetic nanomaterials are capable of transducing magnetic fields into a range of biologically relevant signals in vitro and in vivo. These nanotransducers have recently enabled magnetic control of cellular processes, from neuronal firing and gene expression to programmed apoptosis. Effective implementation of magnetically controlled cellular signalling relies on careful tailoring of magnetic nanotransducers and magnetic fields to the responses of the intended molecular targets. This primer discusses the versatility of magnetic modulation modalities and offers practical guidelines for selection of appropriate materials and field parameters, with a particular focus on applications in neuroscience. With recent developments in magnetic instrumentation and nanoparticle chemistries, including those that are commercially available, magnetic approaches promise to empower research aimed at connecting molecular and cellular signalling to physiology and behaviour in untethered moving subjects.
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Affiliation(s)
- Gabriela Romero
- Department of Biomedical Engineering and Chemical Engineering, University of Texas at San Antonio, San Antonio, TX, USA
| | - Jimin Park
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Florian Koehler
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Arnd Pralle
- Department of Physics, University at Buffalo, the State University of New York, Buffalo, NY, USA
| | - Polina Anikeeva
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
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11
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Zhou R, Li J, Wang R, Chen Z, Zhou F. Moderate systemic therapeutic hypothermia is insufficient to protect blood-spinal cord barrier in spinal cord injury. Front Neurol 2022; 13:1041099. [DOI: 10.3389/fneur.2022.1041099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Accepted: 10/31/2022] [Indexed: 11/17/2022] Open
Abstract
Blood–spinal cord barrier (BSCB) disruption is a pivotal event in spinal cord injury (SCI) that aggravates secondary injury but has no specific treatment. Previous reports have shown that systemic therapeutic hypothermia (TH) can protect the blood–brain barrier after brain injury. To verify whether a similar effect exists on the BSCB after SCI, moderate systemic TH at 32°C was induced for 4 h on the mice with contusion-SCI. In vivo two-photon microscopy was utilized to dynamically monitor the BSCB leakage 1 h after SCI, combined with immunohistochemistry to detect BSCB leakage at 1 and 4 h after SCI. The BSCB leakage was not different between the normothermia (NT) and TH groups at both the in vivo and postmortem levels. The expression of endothelial tight junctions was not significantly different between the NT and TH groups 4 h after SCI, as detected by capillary western blotting. The structural damage of the BSCB was examined with immunofluorescence, but the occurrence of junctional gaps was not changed by TH 4 h after SCI. Our results have shown that moderate systemic TH induced for 4 h does not have a protective effect on the disrupted BSCB in early SCI. This treatment method has a low value and is not recommended for BSCB disruption therapy in early SCI.
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12
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Zhang H, Fu P, Liu Y, Zheng Z, Zhu L, Wang M, Abdellah M, He M, Qian J, Roe AW, Xi W. Large-depth three-photon fluorescence microscopy imaging of cortical microvasculature on nonhuman primates with bright AIE probe In vivo. Biomaterials 2022; 289:121809. [PMID: 36166895 DOI: 10.1016/j.biomaterials.2022.121809] [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: 05/15/2022] [Revised: 09/08/2022] [Accepted: 09/13/2022] [Indexed: 11/02/2022]
Abstract
Multiphoton microscopy has been a powerful tool in brain research, three-photon fluorescence microscopy is increasingly becoming an emerging technique for neurological research of the cortex in depth. Nonhuman primates play important roles in the study of brain science because of their neural and vascular similarity to humans. However, there are few research results of three-photon fluorescence microscopy on the brain of nonhuman primates due to the lack of optimized imaging systems and excellent fluorescent probes. Here we introduced a bright aggregation-induced emission (AIE) probe with excellent three-photon fluorescence efficiency as well as facile synthesis process and we validated its biocompatibility in the macaque monkey. We achieved a large-depth vascular imaging of approximately 1 mm in the cerebral cortex of macaque monkey with our lab-modified three-photon fluorescence microscopy system and the AIE probe. Functional measurement of blood velocity in deep cortex capillaries was also performed. Furthermore, the comparison of cortical deep vascular structure parameters across species was presented on the monkey and mouse cortex. This work is the first in vivo three-photon fluorescence microscopic imaging research on the macaque monkey cortex reaching the imaging depth of ∼1 mm with the bright AIE probe. The results demonstrate the potential of three-photon microscopy as primate-compatible method for imaging fine vascular networks and will advance our understanding of vascular function in normal and disease in humans.
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Affiliation(s)
- Hequn Zhang
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), Department of Anesthesiology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310020, China; MOE Frontier Science Center for Brain Research and Brain Machine Integration, Zhejiang University, Hangzhou, 310058, China; State Key Laboratory of Modern Optical Instrumentations, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, 310058, China
| | - Peng Fu
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), Department of Anesthesiology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310020, China; MOE Frontier Science Center for Brain Research and Brain Machine Integration, Zhejiang University, Hangzhou, 310058, China
| | - Yin Liu
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), Department of Anesthesiology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310020, China; MOE Frontier Science Center for Brain Research and Brain Machine Integration, Zhejiang University, Hangzhou, 310058, China
| | - Zheng Zheng
- School of Chemistry and Chemical Engineering, Hefei University of Technology, Hefei, 230009, China
| | - Liang Zhu
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, 310027, China
| | - Mengqi Wang
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), Department of Anesthesiology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310020, China; MOE Frontier Science Center for Brain Research and Brain Machine Integration, Zhejiang University, Hangzhou, 310058, China
| | - Marwan Abdellah
- Blue Brain Project (BBP), École Polytechnique Fédérale de Lausanne (EPFL), Campus Biotech, 1202, Geneva, Switzerland
| | - Mubin He
- State Key Laboratory of Modern Optical Instrumentations, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, 310058, China
| | - Jun Qian
- State Key Laboratory of Modern Optical Instrumentations, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, 310058, China.
| | - Anna Wang Roe
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), Department of Anesthesiology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310020, China; MOE Frontier Science Center for Brain Research and Brain Machine Integration, Zhejiang University, Hangzhou, 310058, China
| | - Wang Xi
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), Department of Anesthesiology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310020, China; MOE Frontier Science Center for Brain Research and Brain Machine Integration, Zhejiang University, Hangzhou, 310058, China; Key Laboratory of Biomedical Engineering of Ministry of Education, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, 310027, China
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13
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Zhang H, Zhu L, Gao DS, Liu Y, Zhang J, Yan M, Qian J, Xi W. Imaging the Deep Spinal Cord Microvascular Structure and Function with High-Speed NIR-II Fluorescence Microscopy. SMALL METHODS 2022; 6:e2200155. [PMID: 35599368 DOI: 10.1002/smtd.202200155] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 04/23/2022] [Indexed: 06/15/2023]
Abstract
The spinal cord (SC) is crucial for a myriad of somatosensory, autonomic signal processing, and transductions. Understanding the SC vascular structure and function thus plays an integral part in neuroscience and clinical research. However, the dense layers of myelinated ascending axons on the dorsal side inconveniently grant the SC tissue with high optical scattering property, which significantly hinders the imaging depth of the SC vasculature in vivo. Commonly used antiscattering techniques such as multiphoton fluorescence microscopy have low imaging speed and cannot capture the rapid vascular particle flow without significant motion blur. Here, advantage of the high penetration of near-infrared (NIR)-II fluorescence is taken to demonstrate a deep SC vascular structural image stack up to 350 µm, comparable to two-photon microscopy. Furthermore, the red blood cells are labelled with the clinically approved NIR dye indocyanine. The combination of a fast NIR camera and indocyanine green-red blood cells (RBCs) makes it possible to attain high-speed 100 frame-per-second NIR-II imaging to identify the corresponding changes in RBC velocity during the external hind leg stimulus. For the first time, it is established that the NIR-II region would be a promising spectral window for SC imaging. NIR-II fluorescence microscopy has excellent potential for clinical and basic science research on SC.
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Affiliation(s)
- Hequn Zhang
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), Department of Anesthesiology, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310020, China
- MOE Frontier Science Center for Brain Research and Brain Machine Integration, Zhejiang University, Hangzhou, 310058, China
| | - Liang Zhu
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), Department of Anesthesiology, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310020, China
- MOE Frontier Science Center for Brain Research and Brain Machine Integration, Zhejiang University, Hangzhou, 310058, China
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, 310027, China
| | - Dave Schwinn Gao
- Key Laboratory of The Diagnosis and Treatment of Severe Trauma and Burn of Zhejiang Province, Department of Anesthesiology, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310009, China
| | - Yin Liu
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), Department of Anesthesiology, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310020, China
- MOE Frontier Science Center for Brain Research and Brain Machine Integration, Zhejiang University, Hangzhou, 310058, China
| | - Jun Zhang
- Department of Spine Surgery, Zhejiang Provincial People's Hospital, Hangzhou Medical School People's Hospital, Shangtang Road 158th, Hangzhou, Zhejiang Province, 310014, China
| | - Min Yan
- Key Laboratory of The Diagnosis and Treatment of Severe Trauma and Burn of Zhejiang Province, Department of Anesthesiology, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310009, China
| | - Jun Qian
- State Key Laboratory of Modern Optical Instrumentations, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, Zhejiang University, Hangzhou, 310058, China
| | - Wang Xi
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), Department of Anesthesiology, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310020, China
- MOE Frontier Science Center for Brain Research and Brain Machine Integration, Zhejiang University, Hangzhou, 310058, China
- Key Laboratory of Biomedical Engineering of Ministry of Education, College of Biomedical Engineering and instrument Science, Zhejiang University, Hangzhou, 310027, China
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14
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Rodríguez C, Chen A, Rivera JA, Mohr MA, Liang Y, Natan RG, Sun W, Milkie DE, Bifano TG, Chen X, Ji N. An adaptive optics module for deep tissue multiphoton imaging in vivo. Nat Methods 2021; 18:1259-1264. [PMID: 34608309 PMCID: PMC9090585 DOI: 10.1038/s41592-021-01279-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 08/23/2021] [Indexed: 02/08/2023]
Abstract
Understanding complex biological systems requires visualizing structures and processes deep within living organisms. We developed a compact adaptive optics module and incorporated it into two- and three-photon fluorescence microscopes, to measure and correct tissue-induced aberrations. We resolved synaptic structures in deep cortical and subcortical areas of the mouse brain, and demonstrated high-resolution imaging of neuronal structures and somatosensory-evoked calcium responses in the mouse spinal cord at great depths in vivo.
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Affiliation(s)
- Cristina Rodríguez
- Department of Physics, University of California, Berkeley, CA, USA.,Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA.,These authors contributed equally to this work: Cristina Rodríguez, Anderson Chen
| | - Anderson Chen
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA.,Present address: Bio Optical & Acoustic Spectroscopy Lab, Neurophotonics Center, Boston University, Boston, MA, USA.,These authors contributed equally to this work: Cristina Rodríguez, Anderson Chen
| | - José A. Rivera
- Department of Physics, University of California, Berkeley, CA, USA
| | - Manuel A. Mohr
- Department of Biology, Stanford University, Stanford, CA, USA
| | - Yajie Liang
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA.,Present address: Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Ryan G. Natan
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA.,Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Wenzhi Sun
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA.,Present address: School of Basic Medical Sciences, Capital Medical University, Beijing, China,Present address: Chinese Institute for Brain Research, Beijing, China
| | - Daniel E. Milkie
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Thomas G. Bifano
- Department of Mechanical Engineering, Photonics Center, Boston University, Boston, MA, USA.,Present address: Bio Optical & Acoustic Spectroscopy Lab, Neurophotonics Center, Boston University, Boston, MA, USA
| | - Xiaoke Chen
- Department of Biology, Stanford University, Stanford, CA, USA
| | - Na Ji
- Department of Physics, University of California, Berkeley, CA, USA.,Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA.,Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.,Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA.,Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.,Corresponding author:
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15
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Chen L, Hong W, Ren W, Xu T, Qian Z, He Z. Recent progress in targeted delivery vectors based on biomimetic nanoparticles. Signal Transduct Target Ther 2021; 6:225. [PMID: 34099630 PMCID: PMC8182741 DOI: 10.1038/s41392-021-00631-2] [Citation(s) in RCA: 96] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 04/28/2021] [Accepted: 04/29/2021] [Indexed: 02/05/2023] Open
Abstract
Over the past decades, great interest has been given to biomimetic nanoparticles (BNPs) since the rise of targeted drug delivery systems and biomimetic nanotechnology. Biological vectors including cell membranes, extracellular vesicles (EVs), and viruses are considered promising candidates for targeted delivery owing to their biocompatibility and biodegradability. BNPs, the integration of biological vectors and functional agents, are anticipated to load cargos or camouflage synthetic nanoparticles to achieve targeted delivery. Despite their excellent intrinsic properties, natural vectors are deliberately modified to endow multiple functions such as good permeability, improved loading capability, and high specificity. Through structural modification and transformation of the vectors, they are pervasively utilized as more effective vehicles that can deliver contrast agents, chemotherapy drugs, nucleic acids, and genes to target sites for refractory disease therapy. This review summarizes recent advances in targeted delivery vectors based on cell membranes, EVs, and viruses, highlighting the potential applications of BNPs in the fields of biomedical imaging and therapy industry, as well as discussing the possibility of clinical translation and exploitation trend of these BNPs.
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Affiliation(s)
- Li Chen
- Department of Pharmacy, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Weiqi Hong
- Department of Pharmacy, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Wenyan Ren
- Department of Pharmacy, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Ting Xu
- Department of Pharmacy, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, Sichuan, China
- Key Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu, Sichuan, China
| | - Zhiyong Qian
- Department of Pharmacy, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Zhiyao He
- Department of Pharmacy, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, Sichuan, China.
- Key Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu, Sichuan, China.
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16
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Investigating the blood-spinal cord barrier in preclinical models: a systematic review of in vivo imaging techniques. Spinal Cord 2021; 59:596-612. [PMID: 33742118 DOI: 10.1038/s41393-021-00623-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 02/25/2021] [Accepted: 03/01/2021] [Indexed: 01/31/2023]
Abstract
STUDY DESIGN This study is a systematic review. OBJECTIVES To evaluate current in vivo techniques used in the investigation of the blood-spinal cord barrier (BSCB). METHODS Search of English language literature for animal studies that investigated the BSCB in vivo. Data extraction included animal model/type, protocol for BSCB evaluation, and study outcomes. Descriptive syntheses are provided. RESULTS A total of 40 studies were included, which mainly investigated rodent models of experimental autoimmune encephalomyelitis (EAE) or spinal cord injury (SCI). The main techniques used were magnetic resonance imaging (MRI) and intravital microscopy (IVM). MRI served as a reliable tool to longitudinally track BSCB permeability changes with dynamic contrast enhancement (DCE) using gadolinium, or assess inflammatory infiltrations with targeted alternative contrast agents. IVM provided high-resolution visualization of cellular and molecular interactions across the microvasculature, commonly with either epi-fluorescence or two-photon microscopy. MRI and IVM techniques enabled the evaluation of therapeutic interventions and mechanisms that drive spinal cord dysfunction in EAE and SCI. A small number of studies demonstrated the feasibility of DCE-computed tomography, ultrasound, bioluminescent, and fluorescent optical imaging methods to evaluate the BSCB. Technique-specific limitations and multiple protocols for image acquisition and data analyses are described for all techniques. CONCLUSION There are few in vivo investigations of the BSCB. Additional studies are needed in less commonly studied spinal cord disorders, and to establish standardized protocols for data acquisition and analysis. Further development of techniques and multimodal approaches could overcome current imaging limitations to the spinal cord. These advancements might promote wider adoption of techniques, and can provide greater potential for clinical translation.
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17
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Fan W, Sdrulla AD. Differential modulation of excitatory and inhibitory populations of superficial dorsal horn neurons in lumbar spinal cord by Aβ-fiber electrical stimulation. Pain 2021; 161:1650-1660. [PMID: 32068665 DOI: 10.1097/j.pain.0000000000001836] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Activation of Aβ-fibers is fundamental to numerous analgesic therapies, yet its effects on dorsal horn neuronal activity remain unclear. We used multiphoton microscopy of the genetically encoded calcium indicator GCaMP6s to characterize the effects of Aβ-fiber electrical stimulation (Aβ-ES) on neural activity. Specifically, we quantified somatic responses evoked by C-fiber intensity stimulation before and after a 10-minute train of dorsal root Aβ-ES in superficial dorsal horn (SDH) neurons, in mouse lumbar spinal cord. Aβ-ES did not alter C-fiber-evoked activity when GCaMP6s was virally expressed in all neurons, in an intact lumbar spinal cord preparation. However, when we restricted the expression of GCaMP6s to excitatory or inhibitory populations, we observed that Aβ-ES modestly potentiated evoked activity of excitatory neurons and depressed that of inhibitory neurons. Aβ-ES had no significant effects in a slice preparation in either SDH population. A larger proportion of SDH neurons was activated by Aβ-ES when delivered at a root rostral or caudal to the segment where the imaging and C-fiber intensity stimulation occurred. Aβ-ES effects on excitatory and inhibitory populations depended on the root used. Our findings suggest that Aβ-ES differentially modulates lumbar spinal cord SDH populations in a cell type- and input-specific manner. Furthermore, they underscore the importance of the Aβ-ES delivery site, suggesting that Aβ stimulation at a segment adjacent to where the pain is may improve analgesic efficacy.
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Affiliation(s)
- Wei Fan
- Department of Anesthesiology and Perioperative Medicine, Oregon Health & Science University, Portland, OR, United States
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18
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Abstract
The muscle spindle is an important sense organ for motor control and proprioception. Specialized intrafusal fibers are innervated by both stretch sensitive afferents and γ motor neurons that control the length of the spindle and tune the sensitivity of the muscle spindle afferents to both dynamic movement and static length. γ motor neurons share many similarities with other skeletal motor neurons, making it challenging to identify and specifically record or stimulate them. This short review will discuss recent advances in genetic and molecular biology techniques, electrophysiological recording, optical imaging, computer modelling, and stem cell culture techniques that have the potential to help answer important questions about fusimotor function in motor control and disease.
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19
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Rotterman TM, Alvarez FJ. Microglia Dynamics and Interactions with Motoneurons Axotomized After Nerve Injuries Revealed By Two-Photon Imaging. Sci Rep 2020; 10:8648. [PMID: 32457369 PMCID: PMC7250868 DOI: 10.1038/s41598-020-65363-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 05/01/2020] [Indexed: 01/08/2023] Open
Abstract
The significance of activated microglia around motoneurons axotomized after nerve injuries has been intensely debated. In particular, whether microglia become phagocytic is controversial. To resolve these issues we directly observed microglia behaviors with two-photon microscopy in ex vivo spinal cord slices from CX3CR1-GFP mice complemented with confocal analyses of CD68 protein. Axotomized motoneurons were retrogradely-labeled from muscle before nerve injuries. Microglia behaviors close to axotomized motoneurons greatly differ from those within uninjured motor pools. They develop a phagocytic phenotype as early as 3 days after injury, characterized by frequent phagocytic cups, high phagosome content and CD68 upregulation. Interactions between microglia and motoneurons changed with time after axotomy. Microglia first extend processes that end in phagocytic cups at the motoneuron surface, then they closely attach to the motoneuron while extending filopodia over the cell body. Confocal 3D analyses revealed increased microglia coverage of the motoneuron cell body surface with time after injury and the presence of CD68 granules in microglia surfaces opposed to motoneurons. Some microglia formed macroclusters associated with dying motoneurons. Microglia in these clusters display the highest CD68 expression and associate with cytotoxic T-cells. These observations are discussed in relation to current theories on microglia function around axotomized motoneurons.
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Affiliation(s)
- Travis M Rotterman
- Department of Physiology, Emory University, Atlanta, GA, 30322, United States of America.,School of Biological Sciences, Georgia Tech, Atlanta, GA, 30318, United States of America
| | - Francisco J Alvarez
- Department of Physiology, Emory University, Atlanta, GA, 30322, United States of America.
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20
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Borjini N, Paouri E, Tognatta R, Akassoglou K, Davalos D. Imaging the dynamic interactions between immune cells and the neurovascular interface in the spinal cord. Exp Neurol 2019; 322:113046. [PMID: 31472115 DOI: 10.1016/j.expneurol.2019.113046] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 08/16/2019] [Accepted: 08/27/2019] [Indexed: 12/19/2022]
Abstract
Imaging the dynamic interactions between immune cells, glia, neurons and the vasculature in living rodents has revolutionized our understanding of physiological and pathological mechanisms of the CNS. Emerging microscopy and imaging technologies have enabled longitudinal tracking of structural and functional changes in a plethora of different cell types in the brain. The development of novel methods also allowed stable and longitudinal optical access to the spinal cord with minimum tissue perturbation. These important advances facilitated the application of in vivo imaging using two-photon microscopy for studies of the healthy, diseased, or injured spinal cord. Indeed, decoding the interactions between peripheral and resident cells with the spinal cord vasculature has shed new light on neuroimmune and vascular mechanisms regulating the onset and progression of neurological diseases. This review focuses on imaging studies of the interactions between the vasculature and peripheral immune cells or microglia, with emphasis on their contribution to neuroinflammation. We also discuss in vivo imaging studies highlighting the importance of neurovascular changes following spinal cord injury. Real-time imaging of blood-brain barrier (BBB) permeability and other vascular changes, perivascular glial responses, and immune cell entry has revealed unanticipated cellular mechanisms and novel molecular pathways that can be targeted to protect the injured or diseased CNS. Imaging the cell-cell interactions between the vasculature, immune cells, and neurons as they occur in real time, is a powerful tool both for testing the efficacy of existing therapeutic approaches, and for identifying new targets for limiting damage or enhancing the potential for repair of the affected spinal cord tissue.
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Affiliation(s)
- Nozha Borjini
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Evi Paouri
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | | | - Katerina Akassoglou
- Gladstone Institutes, San Francisco, CA, USA; Department of Neurology, University of California, San Francisco, San Francisco, CA, USA
| | - Dimitrios Davalos
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA; Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, USA.
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