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Dibaj P, Safavi-Abbasi S, Asadollahi E. In vivo spectrally unmixed multi-photon imaging of longitudinal axon-glia changes in injured spinal white matter. Neurosci Lett 2024; 841:137959. [PMID: 39218293 DOI: 10.1016/j.neulet.2024.137959] [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: 05/05/2024] [Revised: 08/06/2024] [Accepted: 08/29/2024] [Indexed: 09/04/2024]
Abstract
Understanding the sequence of cellular responses and their contributions to pathomorphogical changes in spinal white matter injuries is a prerequisite for developing efficient therapeutic strategies for spinal cord injury (SCI) as well as neurodegenerative and inflammatory diseases of the spinal cord such as amyotrophic lateral sclerosis and multiple sclerosis. We have developed several types of surgical procedures suitable for acute one-time and chronic recurrent in vivo multiphoton microscopy of spinal white matter [1]. Sophisticated surgical procedures were combined with transgenic mouse technology to image spinal tissue labeled with up to four fluorescent proteins (FPs) in axons, astrocytes, microglia, and blood vessels. To clearly separate the simultaneously excited FPs, spectral unmixing including iterative procedures was performed after imaging the diversely labeled spinal white matter with a custom-made 4-channel two-photon laser-scanning microscope. In our longitudinal multicellular studies of injured spinal white matter, we imaged axonal dynamics and invasion of microglia and astrocytes for a time course of over 200 days after SCI. Our methods offer ideal platforms for investigating acute and chronic cellular dynamics, cell-cell interactions, and metabolite fluctuations in health and disease as well as pharmacological manipulations in vivo.
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Affiliation(s)
- Payam Dibaj
- Center for Rare Diseases Göttingen (ZSEG), Department of Pediatrics, University Medical Center Göttingen, Georg August University, 37075 Göttingen, Germany; Max-Planck-Institute for Multidisciplinary Sciences, 37075 Göttingen, Germany; Department of Neurology, Ökumenisches Hainich Klinikum, 99974 Mühlhausen, Germany.
| | - Sam Safavi-Abbasi
- Neurosurgical Medicine, Yavapai Regional Medical Group, Prescott, AZ 86301, USA
| | - Ebrahim Asadollahi
- Max-Planck-Institute for Multidisciplinary Sciences, 37075 Göttingen, Germany
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2
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da Silva NS, Lombardi J, Kirchhoff F, Ferreira RS, Barraviera B, de Oliveira ALR, Cartarozzi LP. Effects of local and systemic treatment with human natural killer-1 mimetic peptide (HNK-1) after ventral root avulsion and reimplantation in mice. J Venom Anim Toxins Incl Trop Dis 2024; 30:e20230065. [PMID: 38770186 PMCID: PMC11105159 DOI: 10.1590/1678-9199-jvatitd-2023-0065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 04/01/2024] [Indexed: 05/22/2024] Open
Abstract
Background Spinal ventral root injuries generate significant motoneuron degeneration, which hinders full functional recovery. The poor prognosis of functional recovery can be attributed to the use or combination of different therapeutic approaches. Several molecules have been screened as potential treatments in combination with surgical reimplantation of the avulsed roots, the gold standard approach for such injuries. Among the studied molecules, human natural killer-1 (HNK-1) stands out as it is related to the stimulation of motor axon outgrowth. Therefore, we aimed to comparatively investigate the effects of local administration of an HNK-1 mimetic peptide (mp-HNK-1) and systemic treatment with ursolic acid (UA), another HNK-1 mimetic, after ventral root avulsion and reimplantation with heterologous fibrin biopolymer (HFB). Methods Female mice of the isogenic strain C57BL/6JUnib were divided into five experimental groups: Avulsion, Reimplantation, mp-HNK-1 (in situ), and UA (systemic treatment). Mice were evaluated 2 and 12 weeks after surgery. Functional assessment was performed every four days using the Catwalk platform. Neuronal survival was analyzed by cytochemistry, and glial reactions and synaptic coverage were evaluated by immunofluorescence. Results Treatment with UA elicited long-term neuroprotection, accompanied by a decrease in microglial reactions, and reactive astrogliosis. The neuroprotective effects of UA were preceded by increased glutamatergic and GABAergic inputs in the ventral spinal cord two weeks after injury. However, a single application of mp-HNK-1 had no significant effects. Functional analysis showed that UA treatment led to an improvement in motor and sensory recovery. Conclusion Overall, the results indicate that UA is neuroprotective, acting on glial cells and synaptic maintenance, and the combination of these findings led to a better functional recovery.
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Affiliation(s)
- Natalia Scanavachia da Silva
- Department of Structural and Functional Biology, Laboratory of Nerve Regeneration, Institute of Biology, University of Campinas (Unicamp), Campinas, SP, Brazil
| | - Julia Lombardi
- Department of Structural and Functional Biology, Laboratory of Nerve Regeneration, Institute of Biology, University of Campinas (Unicamp), Campinas, SP, Brazil
| | - Frank Kirchhoff
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
- Center for Gender-specific Biology and Medicine (CGBM), University of Saarland, Homburg, Germany
| | - Rui Seabra Ferreira
- Center for the Study of Venoms and Venomous Animals (CEVAP), São Paulo State University (UNESP), Botucatu, SP, Brazil
| | - Benedito Barraviera
- Center for the Study of Venoms and Venomous Animals (CEVAP), São Paulo State University (UNESP), Botucatu, SP, Brazil
| | - Alexandre Leite Rodrigues de Oliveira
- Department of Structural and Functional Biology, Laboratory of Nerve Regeneration, Institute of Biology, University of Campinas (Unicamp), Campinas, SP, Brazil
| | - Luciana Politti Cartarozzi
- Department of Structural and Functional Biology, Laboratory of Nerve Regeneration, Institute of Biology, University of Campinas (Unicamp), Campinas, SP, Brazil
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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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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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Goyal D, Kumar H. In Vivo and 3D Imaging Technique(s) for Spatiotemporal Mapping of Pathological Events in Experimental Model(s) of Spinal Cord Injury. ACS Chem Neurosci 2023; 14:809-819. [PMID: 36787542 DOI: 10.1021/acschemneuro.2c00643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023] Open
Abstract
Endothelial damage, astrogliosis, microgliosis, and neuronal degeneration are the most common events after spinal cord injury (SCI). Studies highlighted that studying the spatiotemporal profile of these events might provide a deeper understanding of the pathophysiology of SCI. For imaging of these events, available conventional techniques such as 2-dimensional histology and immunohistochemistry (IHC) are well established and frequently used to visualize and detect the altered expression of the protein of interest involved in these events. However, the technique requires the physical sectioning of the tissue, and results are also open to misinterpretation. Currently, researchers are focusing more attention toward the advanced tools for imaging the spinal cord's various physiological and pathological parameters. The tools include two-photon imaging, light sheet fluorescence microscopy, in vivo imaging system with fluorescent probes, and in vivo chemical and fluorescent protein-expressing viral-tracers. These techniques outperform the limitations associated with conventional techniques in various aspects, such as optical sectioning of tissue, 3D reconstructed imaging, and imaging of particular planes of interest. In addition to this, these techniques are minimally invasive and less time-consuming. In this review, we will discuss the various advanced imaging methodologies that will evolve in the future to explore the fundamental mechanisms after SCI.
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Affiliation(s)
- Divya Goyal
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)-Ahmedabad, Gandhinagar, Gujarat India, 382355
| | - Hemant Kumar
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)-Ahmedabad, Gandhinagar, Gujarat India, 382355
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Rieder P, Gobbo D, Stopper G, Welle A, Damo E, Kirchhoff F, Scheller A. Astrocytes and Microglia Exhibit Cell-Specific Ca2+ Signaling Dynamics in the Murine Spinal Cord. Front Mol Neurosci 2022; 15:840948. [PMID: 35431801 PMCID: PMC9006623 DOI: 10.3389/fnmol.2022.840948] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 02/22/2022] [Indexed: 12/31/2022] Open
Abstract
The spinal cord is the main pathway connecting brain and peripheral nervous system. Its functionality relies on the orchestrated activity of both neurons and glial cells. To date, most advancement in understanding the spinal cord inner mechanisms has been made either by in vivo exposure of its dorsal surface through laminectomy or by acute ex vivo slice preparation, likely affecting spinal cord physiology in virtue of the necessary extensive manipulation of the spinal cord tissue. This is especially true of cells immediately responding to alterations of the surrounding environment, such as microglia and astrocytes, reacting within seconds or minutes and for up to several days after the original insult. Ca2+ signaling is considered one of the most immediate, versatile, and yet elusive cellular responses of glia. Here, we induced the cell-specific expression of the genetically encoded Ca2+ indicator GCaMP3 to evaluate spontaneous intracellular Ca2+ signaling in astrocytes and microglia. Ca2+ signals were then characterized in acute ex vivo (both gray and white matter) as well as in chronic in vivo (white matter) preparations using MSparkles, a MATLAB-based software for automatic detection and analysis of fluorescence events. As a result, we were able to segregate distinct astroglial and microglial Ca2+ signaling patterns along with method-specific Ca2+ signaling alterations, which must be taken into consideration in the reliable evaluation of any result obtained in physiological as well as pathological conditions. Our study revealed a high degree of Ca2+ signaling diversity in glial cells of the murine spinal cord, thus adding to the current knowledge of the astonishing glial heterogeneity and cell-specific Ca2+ dynamics in non-neuronal networks.
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Affiliation(s)
- Phillip Rieder
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Davide Gobbo
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Gebhard Stopper
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Anna Welle
- Department of Genetics and Epigenetics, University of Saarland, Saarbrücken, Germany
| | - Elisa Damo
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
- Institute of Pharmacology, Medical Faculty Heidelberg, Heidelberg University, Heidelberg, Germany
| | - Frank Kirchhoff
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Anja Scheller
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
- *Correspondence: Anja Scheller,
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Darras A, Breunig HG, John T, Zhao R, Koch J, Kummerow C, König K, Wagner C, Kaestner L. Imaging Erythrocyte Sedimentation in Whole Blood. Front Physiol 2022; 12:729191. [PMID: 35153805 PMCID: PMC8832033 DOI: 10.3389/fphys.2021.729191] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 11/23/2021] [Indexed: 11/13/2022] Open
Abstract
The erythrocyte sedimentation rate (ESR) is one of the oldest medical diagnostic tools. However, currently there is some debate on the structure formed by the cells during the sedimentation process. While the conventional view is that erythrocytes sediment as separate aggregates, others have suggested that they form a percolating gel, similar to other colloidal suspensions. However, visualization of aggregated erythrocytes, which would settle the question, has always been challenging. Direct methods usually study erythrocytes in 2D situations or low hematocrit (∼1%). Indirect methods, such as scattering or electric measurements, provide insight on the suspension evolution, but cannot directly discriminate between open or percolating structures. Here, we achieved a direct probing of the structures formed by erythrocytes in blood at stasis. We focused on blood samples at rest with controlled hematocrit of 45%, from healthy donors, and report observations from three different optical imaging techniques: direct light transmission through thin samples, two-photon microscopy and light-sheet microscopy. The three techniques, used in geometries with thickness from 150 μm to 3 mm, highlight that erythrocytes form a continuous network with characteristic cracks, i.e., a colloidal gel. The characteristic distance between the main cracks is of the order of ∼100 μm. A complete description of the structure then requires a field of view of the order of ∼1 mm, in order to obtain a statistically relevant number of structural elements. A quantitative analysis of the erythrocyte related processes and interactions during the sedimentation need a further refinement of the experimental set-ups.
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Affiliation(s)
- Alexis Darras
- Experimental Physics, Saarland University, Saarbrücken, Germany
| | - Hans Georg Breunig
- Biophotonics and Laser Technology, Saarland University, Saarbrücken, Germany
| | - Thomas John
- Experimental Physics, Saarland University, Saarbrücken, Germany
| | - Renping Zhao
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg, Germany
| | - Johannes Koch
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg, Germany
| | - Carsten Kummerow
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg, Germany
| | - Karsten König
- Biophotonics and Laser Technology, Saarland University, Saarbrücken, Germany
- JenLab GmbH, Berlin, Germany
| | - Christian Wagner
- Experimental Physics, Saarland University, Saarbrücken, Germany
- Department of Physics and Materials Science, University of Luxembourg, Luxembourg City, Luxembourg
| | - Lars Kaestner
- Experimental Physics, Saarland University, Saarbrücken, Germany
- Theoretical Medicine and Biosciences, Saarland University, Homburg, Germany
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Cartarozzi LP, Perez M, Fernandes GG, Chiarotto GB, Luzo ÂCM, Campos AC, Kirchhoff F, de Oliveira ALR. Neuroprotection and gliosis attenuation by intravenous application of human mesenchymal stem cells (hMSC) following ventral root crush in mice. Mol Cell Neurosci 2021; 118:103694. [PMID: 34954382 DOI: 10.1016/j.mcn.2021.103694] [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: 06/09/2021] [Revised: 12/13/2021] [Accepted: 12/17/2021] [Indexed: 11/15/2022] Open
Abstract
Rupture and stretching of spinal roots are common incidents that take place in high-energy accidents. The proximal axotomy of motoneurons by crushing of ventral roots is directly related to the degeneration of half of the lesioned population within the first two weeks. Moreover, only a small percentage of surviving motoneurons can successfully achieve regeneration after such a proximal lesion, and new treatments are necessary to improve this scenario. In this sense, mesenchymal stem cells (MSC) are of great interest once they secrete a broad spectrum of bioactive molecules that are immunomodulatory and can restore the environment after a lesion. The present work aimed at studying the effects of human mesenchymal stem cells (hMSC) therapy after ventral root crush (VRC) in mice. We evaluated motoneuron survival, glial reaction, and synapse preservation at the ventral horn. For this purpose, C57BL/6 J were submitted to a crush procedure of L4 to L6 ventral roots and treated with a single intravenous injection of adipose-derived hMSC. Evaluation of the results was carried out at 7, 14, and 28 days after injury. Analysis of motoneuron survival and astrogliosis showed that hMSC treatment resulted in higher motoneuron preservation (motoneuron survival ipsi/contralateral ratio: VRC group = 53%, VRC + hMSC group = 66%; p < 0.01), combined with reduction of astrogliosis (ipsi/contralateral GFAP immunolabeling: VRC group = 470%, VRC + hMSC group = 250%; p < 0.001). The morphological classification and Sholl analysis of microglial activation revealed that hMSC treatment reduced type V and increased type II profiles, indicating an enhancement of surveying over activated microglial cells. The glial reactivity modulation directly influenced synaptic inputs in apposition to axotomized motoneurons. In the hMSC-treated group, synaptic maintenance was increased (ipsi/contralateral synaptophysin immunolabeling: VRC group = 53%, VRC + hMSC group = 64%; p < 0.05). Overall, the present data show that intravenous injection of hMSC has neuroprotective and anti-inflammatory effects, decreasing reactive astrogliosis, and microglial reaction. Also, such cell therapy results in motoneuron preservation, combined with significant maintenance of spinal cord circuits, in particular those related to the ventral horn.
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Affiliation(s)
- Luciana Politti Cartarozzi
- Laboratory of Nerve Regeneration, University of Campinas - UNICAMP, Cidade Universitaria "Zeferino Vaz", Rua Monteiro Lobato, 255, 13083-970 Campinas, SP, Brazil
| | - Matheus Perez
- School of Physical Education and Sport of Ribeirão Preto, University of São Paulo, Av. Bandeirantes, 3900, 14040-907 Ribeirão Preto, SP, Brazil
| | - Gabriel Gripp Fernandes
- Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Av. Bandeirantes, 3900, 14040-907 Ribeirão Preto, SP, Brazil
| | - Gabriela Bortolança Chiarotto
- Laboratory of Nerve Regeneration, University of Campinas - UNICAMP, Cidade Universitaria "Zeferino Vaz", Rua Monteiro Lobato, 255, 13083-970 Campinas, SP, Brazil
| | - Ângela Cristina Malgeiros Luzo
- Hematology and Hemotherapy Center, University of Campinas/Hemocentro-Unicamp, Instituto Nacional de Ciência e Tecnologia do Sangue, Campinas, São Paulo, Brazil
| | - Alline Cristina Campos
- Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Av. Bandeirantes, 3900, 14040-907 Ribeirão Preto, SP, Brazil
| | - Frank Kirchhoff
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Building 48, 66421 Homburg, Germany
| | - Alexandre Leite Rodrigues de Oliveira
- Laboratory of Nerve Regeneration, University of Campinas - UNICAMP, Cidade Universitaria "Zeferino Vaz", Rua Monteiro Lobato, 255, 13083-970 Campinas, SP, Brazil.
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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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10
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Carvalho NZM, Chiarotto GB, Bernardes D, Kempe PRG, Oliveira ALR. Neuroprotection by dimethyl fumarate following ventral root crush in C57BL/6J mice. Brain Res Bull 2020; 164:184-197. [PMID: 32866558 DOI: 10.1016/j.brainresbull.2020.08.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 07/22/2020] [Accepted: 08/13/2020] [Indexed: 01/22/2023]
Abstract
CNS lesions usually result in permanent loss of function and are an important problem in the medical field. In order to investigate neuroprotection/degeneration mechanisms and the synaptic plasticity of motoneurons, in addition to the potential for a variety of treatments, different experimental models of axonal injury have been proposed. Recent studies have tested the immunomodulatory drug dimethyl fumarate (DMF) for the treatment of neurodegenerative diseases and have shown promising outcomes. Therefore, in this work, we investigated the effects of DMF with regard to neuroprotection and its influence on the glial response in C57BL/6J animals subjected to crushing of the motor roots in the lumbar intumescence of the spinal cord. The animals were divided into a vehicle-treated injury group (0.08 % methylcellulose solution control group, n = 7) and injured groups treated with DMF at different doses (15, 30, 45, 90 and 180 mg/kg; n = 6-7 per dose). The 90 mg/kg dose showed the best neuroprotective results, so it was used for treatment over a period of eight weeks. Neuronal survival was assessed through Nissl staining, and functional recovery was evaluated with the CatWalk system (walking track test) and the von Frey test (mechanoreception). Immunohistochemistry was used to assess synaptic coverage and astroglial and microglial reactivity using the primary antibodies anti-synaptophysin (pre-synaptic terminal pan marker), GAD65 (GABAergic pre-synaptic terminations - inhibitory), and VGLUT1 (glutamatergic pre-synaptic terminations - excitatory). Glial reactions were evaluated with anti-IBA1 (microglia) and GFAP (astrocytes). Gene transcript levels of IL-3, IL-4, TNF-α, IL-6, TGF-β, iNOS-M1, and arginase-M2 were quantified by RT-qPCR. The results indicated that treatment with DMF, at a dose of 90 mg/kg, promoted neuroprotection and immunomodulation towards an anti-inflammatory response. It also resulted in greater preservation of inhibitory synapses and reduced astroglial reactivity, providing a more favorable environment for sensorimotor recovery.
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Affiliation(s)
| | - Gabriela Bortolança Chiarotto
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas - UNICAMP. 13083-970, Campinas, SP, Brazil; University Center of Herminio Ometto Foundation, Post Graduate Program in Biomedical Science, Brazil.
| | - Danielle Bernardes
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas - UNICAMP. 13083-970, Campinas, SP, Brazil; University Center of Herminio Ometto Foundation, Post Graduate Program in Biomedical Science, Brazil.
| | - Paula Regina Gelinski Kempe
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas - UNICAMP. 13083-970, Campinas, SP, Brazil.
| | - Alexandre Leite Rodrigues Oliveira
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas - UNICAMP. 13083-970, Campinas, SP, Brazil.
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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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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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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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Nelson NA, Wang X, Cook D, Carey EM, Nimmerjahn A. Imaging spinal cord activity in behaving animals. Exp Neurol 2019; 320:112974. [PMID: 31175843 DOI: 10.1016/j.expneurol.2019.112974] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 06/02/2019] [Accepted: 06/04/2019] [Indexed: 01/06/2023]
Abstract
The spinal cord is the primary neurological link between the brain and peripheral organs. How important it is in everyday life is apparent in patients with spinal cord injury or motoneuron disease, who have dramatically reduced musculoskeletal control or capacity to sense their environment. Despite its crucial role in sensory and motor processing little is known about the cellular and molecular signaling events that underlie spinal cord function under naturalistic conditions. While genetic, electrophysiological, pharmacological, and circuit tracing studies have revealed important roles for different molecularly defined neurons, these approaches insufficiently describe the moment-to-moment neuronal and non-neuronal activity patterns that underlie sensory-guided motor behaviors in health and disease. The recent development of imaging methods for real-time interrogation of cellular activity in the spinal cord of behaving mice has removed longstanding technical obstacles to spinal cord research and allowed new insight into how different cell types encode sensory information from mechanoreceptors and nociceptors in the skin. Here, we review the current state-of-the-art in interrogating cellular and microcircuit function in the spinal cord of behaving mammals and discuss current opportunities and technological challenges.
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Affiliation(s)
- Nicholas A Nelson
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA; Biologial Sciences Graduate Program, University of California, San Diego, La Jolla, CA 92037, USA
| | - Xiang Wang
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Daniela Cook
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Erin M Carey
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Axel Nimmerjahn
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA.
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15
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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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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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17
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Liang Y, Zhang J, Walczak P, Bulte JWM. Quantification of motor neuron loss and muscular atrophy in ricin-induced focal nerve injury. J Neurosci Methods 2018; 308:142-150. [PMID: 30056087 PMCID: PMC6251705 DOI: 10.1016/j.jneumeth.2018.07.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 07/07/2018] [Accepted: 07/18/2018] [Indexed: 12/13/2022]
Abstract
BACKGROUND Intrasciatic nerve injection of the Ricinus communis agglutinin (RCA or ricin) causes degeneration of motor neurons (MNs) with functional deficits, such as those that occur in amyotrophic lateral sclerosis (ALS). The objective of this study was to develop a new comprehensive platform for quantitative evaluation of MN loss, muscular atrophy and behavioral deficits using different ricin injection regimens. NEW METHOD Fluorogold (FG)-guided stereological quantification of MNs, in vivo magnetic resonance imaging (MRI) of muscular atrophy, and CatWalk behavioral testing were used to evaluate the outcome of rats treated with different ricin regimens (RCA60 0.5 μg, RCA60 3 μg, and RCA120 6 μg) as animal models of MN degeneration. RESULTS FG-guided stereological counting of MNs enabled identification, dissection and robust quantification of ricin-induced MN loss. The RCA60 0.5 μg and RCA120 6 μg regimens were found to be best suited as preclinical MN depletion models, with a low mortality and a reproducible MN loss, accompanied by muscle atrophy and functional deficits evaluated by MRI and the CatWalk method, respectively. COMPARISON WITH EXISTING METHODS 1) Fluorogold neuronal tracing provides a robust and straightforward means for quantifying MN loss in the spinal cord; 2) MRI is well-suited to non-invasively assess muscle atrophy; and 3) The CatWalk method is more flexible than rotarod test for studying motor deficits. CONCLUSION Intrasciatic injection of RCA60 or RCA120 induces nerve injury and muscle atrophy, which can be properly evaluated by a comprehensive platform using FG-guided quantitative 3D topographic histological analysis, MRI and the CatWalk behavioral test.
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Affiliation(s)
- Yajie Liang
- Russell H. Morgan Dept. of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA; Cellular Imaging Section and Vascular Biology Program, Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Jiangyang Zhang
- Russell H. Morgan Dept. of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Piotr Walczak
- Russell H. Morgan Dept. of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA; Cellular Imaging Section and Vascular Biology Program, Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA; Department of Neurology and Neurosurgery, Faculty of Medical Sciences, University of Warmia and Mazury, Olsztyn, Poland
| | - Jeff W M Bulte
- Russell H. Morgan Dept. of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA; Cellular Imaging Section and Vascular Biology Program, Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA; Dept. of Chemical & Biomolecular Engineering, The Johns Hopkins University Whiting School of Engineering, Baltimore, MD, 21205, USA; Dept. of Oncology, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA; Dept of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
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