1
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Morris GP, Foster CG, Sutherland BA, Grubb S. Microglia contact cerebral vasculature through gaps between astrocyte endfeet. J Cereb Blood Flow Metab 2024:271678X241280775. [PMID: 39253821 DOI: 10.1177/0271678x241280775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 09/11/2024]
Abstract
The close spatial relationship between microglia and cerebral blood vessels implicates microglia in vascular development, homeostasis and disease. In this study we used the publicly available Cortical MM^3 electron microscopy dataset to systematically investigate microglial interactions with the vasculature. Our analysis revealed that approximately 20% of microglia formed direct contacts with blood vessels through gaps between adjacent astrocyte endfeet. We termed these contact points "plugs". Plug-forming microglia exhibited closer proximity to blood vessels than non-plug forming microglia and formed multiple plugs, predominantly near the soma, ranging in surface area from ∼0.01 μm2 to ∼15 μm2. Plugs were enriched at the venule end of the vascular tree and displayed a preference for contacting endothelial cells over pericytes at a ratio of 3:1. In summary, we provide novel insights into the ultrastructural relationship between microglia and the vasculature, laying a foundation for understanding how these contacts contribute to the functional cross-talk between microglia and cells of the vasculature in health and disease.
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Affiliation(s)
- Gary P Morris
- Tasmanian School of Medicine, College of Health and Medicine, University of Tasmania, Hobart, Tasmania, Australia
| | - Catherine G Foster
- Tasmanian School of Medicine, College of Health and Medicine, University of Tasmania, Hobart, Tasmania, Australia
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA, USA
| | - Brad A Sutherland
- Tasmanian School of Medicine, College of Health and Medicine, University of Tasmania, Hobart, Tasmania, Australia
| | - Søren Grubb
- Center for Translational Neuromedicine, Faculty of Health Sciences, University of Copenhagen, Copenhagen N, Denmark
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2
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Campbell KR, Hallada LP, Huang YS, Solecki DJ. From Blur to Brilliance: The Ascendance of Advanced Microscopy in Neuronal Cell Biology. Annu Rev Neurosci 2024; 47:235-253. [PMID: 38608643 DOI: 10.1146/annurev-neuro-111020-090208] [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] [Indexed: 04/14/2024]
Abstract
The intricate network of the brain's neurons and synapses poses unparalleled challenges for research, distinct from other biological studies. This is particularly true when dissecting how neurons and their functional units work at a cell biological level. While traditional microscopy has been foundational, it was unable to reveal the deeper complexities of neural interactions. However, an imaging renaissance has transformed our capabilities. Advancements in light and electron microscopy, combined with correlative imaging, now achieve unprecedented resolutions, uncovering the most nuanced neural structures. Maximizing these tools requires more than just technical proficiency. It is crucial to align research aims, allocate resources wisely, and analyze data effectively. At the heart of this evolution is interdisciplinary collaboration, where various experts come together to translate detailed imagery into significant biological insights. This review navigates the latest developments in microscopy, underscoring both the promise of and prerequisites for bending this powerful tool set to understanding neuronal cell biology.
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Affiliation(s)
- Kirby R Campbell
- Neuronal Cell Biology Division, Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA;
| | - Liam P Hallada
- St. Jude Graduate School of Biomedical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
- Neuronal Cell Biology Division, Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA;
| | - Yu-Shan Huang
- Neuronal Cell Biology Division, Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA;
| | - David J Solecki
- Neuronal Cell Biology Division, Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA;
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3
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Smets NG, van der Panne SA, Strijkers GJ, Bakker ENTP. Perivascular spaces around arteries exceed perivenous spaces in the mouse brain. Sci Rep 2024; 14:17655. [PMID: 39085283 PMCID: PMC11291892 DOI: 10.1038/s41598-024-67885-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Accepted: 07/17/2024] [Indexed: 08/02/2024] Open
Abstract
The perivascular space (PVS) surrounds cerebral blood vessels and plays an important role in clearing waste products from the brain. Their anatomy and function have been described for arteries, but PVS around veins remain poorly characterized. Using in vivo 2-photon imaging in mice, we determined the size of the PVS around arteries and veins, and their connection with the subarachnoid space. After infusion of 70 kD FITC-dextran into the cerebrospinal fluid via the cisterna magna, labeled PVS were evident around arteries, but veins showed less frequent labeling of the PVS. The size of the PVS correlated with blood vessel size for both pial arteries and veins, but not for penetrating vessels. The PVS around pial arteries and veins was separated from the subarachnoid space by a thin meningeal layer, which did not form a barrier for the tracer. In vivo, FITC-dextran signal was observed adjacent to the vessel wall, but minimally within the wall itself. Post-mortem, there was a significant shift in the tracer's location within the arterial wall, extending into the smooth muscle layer. Taken together, these findings suggest that the PVS around veins has a limited role in the exchange of solutes between CSF and brain parenchyma.
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Affiliation(s)
- Nina G Smets
- Department of Biomedical Engineering and Physics, Amsterdam University Medical Center, Amsterdam, The Netherlands
- Amsterdam Neuroscience Research Institute, Amsterdam, Netherlands
- Amsterdam Cardiovascular Sciences Research Institute, Amsterdam, Netherlands
| | - Shakira A van der Panne
- Department of Biomedical Engineering and Physics, Amsterdam University Medical Center, Amsterdam, The Netherlands
- Amsterdam Neuroscience Research Institute, Amsterdam, Netherlands
- Amsterdam Cardiovascular Sciences Research Institute, Amsterdam, Netherlands
| | - Gustav J Strijkers
- Department of Biomedical Engineering and Physics, Amsterdam University Medical Center, Amsterdam, The Netherlands
- Amsterdam Cardiovascular Sciences Research Institute, Amsterdam, Netherlands
| | - Erik N T P Bakker
- Department of Biomedical Engineering and Physics, Amsterdam University Medical Center, Amsterdam, The Netherlands.
- Amsterdam Neuroscience Research Institute, Amsterdam, Netherlands.
- Amsterdam Cardiovascular Sciences Research Institute, Amsterdam, Netherlands.
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4
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Oltmer J, Mattern H, Beck J, Yakupov R, Greenberg SM, Zwanenburg JJ, Arts T, Düzel E, van Veluw SJ, Schreiber S, Perosa V. Enlarged perivascular spaces in the basal ganglia are associated with arteries not veins. J Cereb Blood Flow Metab 2024:271678X241260629. [PMID: 38863151 DOI: 10.1177/0271678x241260629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 06/13/2024]
Abstract
Enlarged perivascular spaces (EPVS) are common in cerebral small vessel disease (CSVD) and have been identified as a marker of dysfunctional brain clearance. However, it remains unknown if the enlargement occurs predominantly around arteries or veins. We combined in vivo ultra-high-resolution MRI and histopathology to investigate the spatial relationship of veins and arteries with EPVS within the basal ganglia (BG). Furthermore, we assessed the relationship between the EPVS and measures of blood-flow (blood-flow velocity, pulsatility index) in the small arteries of the BG. Twenty-four healthy controls, twelve non-CAA CSVD patients, and five probable CAA patients underwent a 3 tesla [T] and 7T MRI-scan, and EPVS, arteries, and veins within the BG were manually segmented. Furthermore, the scans were co-registered. Six autopsy-cases were also assessed. In the BG, EPVS were significantly closer to and overlapped more frequently with arteries than with veins. Histological analysis showed a higher proportion of BG EPVS surrounding arteries than veins. Finally, the pulsatility index of BG arteries correlated with EPVS volume. Our results are in line with previous works and establish a pathophysiological relationship between arteries and EPVS, contributing to elucidating perivascular clearance routes in the human brain.
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Affiliation(s)
- Jan Oltmer
- Athinoula A. Martinos Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
- Department of Digital Health & Innovation, Vivantes Netzwerk für Gesundheit GmbH, Berlin, Germany
| | - Hendrik Mattern
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
- Department of Biomedical Magnetic Resonance (BMMR), Institute for Physics, Otto-von-Guericke-University, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
| | - Julia Beck
- Department of Neurology, Otto-Von-Guericke University, Magdeburg, Germany
| | - Renat Yakupov
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
- Institute of Cognitive Neurology and Dementia Research (IKND), Otto-von-Guericke University, Magdeburg, Germany
| | - Steven M Greenberg
- J. Philip Kistler Stroke Research Center, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Jaco Jm Zwanenburg
- Center for Image Sciences, University Medical Center Utrecht, Utrecht, Netherlands
| | - Tine Arts
- Center for Image Sciences, University Medical Center Utrecht, Utrecht, Netherlands
| | - Emrah Düzel
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
- Institute of Cognitive Neurology and Dementia Research (IKND), Otto-von-Guericke University, Magdeburg, Germany
- Institute of Cognitive Neuroscience, University College London, London, UK
| | - Susanne J van Veluw
- J. Philip Kistler Stroke Research Center, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- Massachusetts General Hospital, MassGeneral Institute for Neurodegenerative Disease, Charlestown, MA, USA
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Stefanie Schreiber
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
- Department of Neurology, Otto-Von-Guericke University, Magdeburg, Germany
- Department of Neurology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Valentina Perosa
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
- J. Philip Kistler Stroke Research Center, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
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5
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Yang P, Li Y, Qian K, Zhou L, Cheng Y, Wu J, Xu M, Wang T, Yang X, Mu Y, Liu X, Zhang Q. Precise Modulation of Pericyte Dysfunction by a Multifunctional Nanoprodrug to Ameliorate Alzheimer's Disease. ACS NANO 2024; 18:14348-14366. [PMID: 38768086 DOI: 10.1021/acsnano.4c00480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Pericyte dysfunction severely undermines cerebrovascular integrity and exacerbates neurodegeneration in Alzheimer's disease (AD). However, pericyte-targeted therapy is a yet-untapped frontier for AD. Inspired by the elevation of vascular cell adhesion molecule-1 (VCAM-1) and reactive oxygen species (ROS) levels in pericyte lesions, we fabricated a multifunctional nanoprodrug by conjugating the hybrid peptide VLC, a fusion of the VCAM-1 high-affinity peptide VHS and the neuroprotective apolipoprotein mimetic peptide COG1410, to curcumin (Cur) through phenylboronic ester bond (VLC@Cur-NPs) to alleviate complex pericyte-related pathological changes. Importantly, VLC@Cur-NPs effectively homed to pericyte lesions via VLC and released their contents upon ROS stimulation to maximize their regulatory effects. Consequently, VLC@Cur-NPs markedly increased pericyte regeneration to form a positive feedback loop and thus improved neurovascular function and ultimately alleviated memory defects in APP/PS1 transgenic mice. We present a promising therapeutic strategy for AD that can precisely modulate pericytes and has the potential to treat other cerebrovascular diseases.
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Affiliation(s)
- Peng Yang
- Key Laboratory of Smart Drug Delivery, Ministry of Education, & State Key Laboratory of Molecular Engineering of Polymers, School of Pharmacy, Fudan University, Shanghai 201203, People's Republic of China
| | - Yixian Li
- Key Laboratory of Smart Drug Delivery, Ministry of Education, & State Key Laboratory of Molecular Engineering of Polymers, School of Pharmacy, Fudan University, Shanghai 201203, People's Republic of China
| | - Kang Qian
- Key Laboratory of Smart Drug Delivery, Ministry of Education, & State Key Laboratory of Molecular Engineering of Polymers, School of Pharmacy, Fudan University, Shanghai 201203, People's Republic of China
| | - Lingling Zhou
- Key Laboratory of Smart Drug Delivery, Ministry of Education, & State Key Laboratory of Molecular Engineering of Polymers, School of Pharmacy, Fudan University, Shanghai 201203, People's Republic of China
| | - Yunlong Cheng
- Key Laboratory of Smart Drug Delivery, Ministry of Education, & State Key Laboratory of Molecular Engineering of Polymers, School of Pharmacy, Fudan University, Shanghai 201203, People's Republic of China
| | - Jing Wu
- Key Laboratory of Smart Drug Delivery, Ministry of Education, & State Key Laboratory of Molecular Engineering of Polymers, School of Pharmacy, Fudan University, Shanghai 201203, People's Republic of China
| | - Minjun Xu
- Key Laboratory of Smart Drug Delivery, Ministry of Education, & State Key Laboratory of Molecular Engineering of Polymers, School of Pharmacy, Fudan University, Shanghai 201203, People's Republic of China
| | - Tianying Wang
- Key Laboratory of Smart Drug Delivery, Ministry of Education, & State Key Laboratory of Molecular Engineering of Polymers, School of Pharmacy, Fudan University, Shanghai 201203, People's Republic of China
| | - Xiyu Yang
- Key Laboratory of Smart Drug Delivery, Ministry of Education, & State Key Laboratory of Molecular Engineering of Polymers, School of Pharmacy, Fudan University, Shanghai 201203, People's Republic of China
| | - Yongkang Mu
- Key Laboratory of Smart Drug Delivery, Ministry of Education, & State Key Laboratory of Molecular Engineering of Polymers, School of Pharmacy, Fudan University, Shanghai 201203, People's Republic of China
| | - Xuan Liu
- Key Laboratory of Smart Drug Delivery, Ministry of Education, & State Key Laboratory of Molecular Engineering of Polymers, School of Pharmacy, Fudan University, Shanghai 201203, People's Republic of China
| | - Qizhi Zhang
- Key Laboratory of Smart Drug Delivery, Ministry of Education, & State Key Laboratory of Molecular Engineering of Polymers, School of Pharmacy, Fudan University, Shanghai 201203, People's Republic of China
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6
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van Veluw SJ, Benveniste H, Bakker ENTP, Carare RO, Greenberg SM, Iliff JJ, Lorthois S, Van Nostrand WE, Petzold GC, Shih AY, van Osch MJP. Is CAA a perivascular brain clearance disease? A discussion of the evidence to date and outlook for future studies. Cell Mol Life Sci 2024; 81:239. [PMID: 38801464 PMCID: PMC11130115 DOI: 10.1007/s00018-024-05277-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 04/20/2024] [Accepted: 05/13/2024] [Indexed: 05/29/2024]
Abstract
The brain's network of perivascular channels for clearance of excess fluids and waste plays a critical role in the pathogenesis of several neurodegenerative diseases including cerebral amyloid angiopathy (CAA). CAA is the main cause of hemorrhagic stroke in the elderly, the most common vascular comorbidity in Alzheimer's disease and also implicated in adverse events related to anti-amyloid immunotherapy. Remarkably, the mechanisms governing perivascular clearance of soluble amyloid β-a key culprit in CAA-from the brain to draining lymphatics and systemic circulation remains poorly understood. This knowledge gap is critically important to bridge for understanding the pathophysiology of CAA and accelerate development of targeted therapeutics. The authors of this review recently converged their diverse expertise in the field of perivascular physiology to specifically address this problem within the framework of a Leducq Foundation Transatlantic Network of Excellence on Brain Clearance. This review discusses the overarching goal of the consortium and explores the evidence supporting or refuting the role of impaired perivascular clearance in the pathophysiology of CAA with a focus on translating observations from rodents to humans. We also discuss the anatomical features of perivascular channels as well as the biophysical characteristics of fluid and solute transport.
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Affiliation(s)
- Susanne J van Veluw
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
| | - Helene Benveniste
- Department of Anesthesiology, Yale School of Medicine, New Haven, CT, USA
| | - Erik N T P Bakker
- Department of Biomedical Engineering, Amsterdam University Medical Center, Location AMC, Amsterdam Neuroscience Research Institute, Amsterdam, The Netherlands
| | - Roxana O Carare
- Clinical Neurosciences, University of Southampton, Southampton, UK
| | - Steven M Greenberg
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Jeffrey J Iliff
- VA Puget Sound Health Care System, University of Washington, Seattle, WA, USA
| | - Sylvie Lorthois
- Institut de Mécanique Des Fluides de Toulouse, IMFT, Université de Toulouse, CNRS, Toulouse, France
| | - William E Van Nostrand
- Department of Biomedical and Pharmaceutical Science, George & Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI, USA
| | - Gabor C Petzold
- German Center for Neurodegenerative Disease, Bonn, Germany
- Division of Vascular Neurology, Department of Neurology, University Hospital Bonn, Bonn, Germany
| | - Andy Y Shih
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, University of Washington, Seattle, WA, USA
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7
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Agarwal N, Lewis LD, Hirschler L, Rivera LR, Naganawa S, Levendovszky SR, Ringstad G, Klarica M, Wardlaw J, Iadecola C, Hawkes C, Octavia Carare R, Wells J, Bakker EN, Kurtcuoglu V, Bilston L, Nedergaard M, Mori Y, Stoodley M, Alperin N, de Leon M, van Osch MJ. Current Understanding of the Anatomy, Physiology, and Magnetic Resonance Imaging of Neurofluids: Update From the 2022 "ISMRM Imaging Neurofluids Study group" Workshop in Rome. J Magn Reson Imaging 2024; 59:431-449. [PMID: 37141288 PMCID: PMC10624651 DOI: 10.1002/jmri.28759] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 04/18/2023] [Accepted: 04/18/2023] [Indexed: 05/05/2023] Open
Abstract
Neurofluids is a term introduced to define all fluids in the brain and spine such as blood, cerebrospinal fluid, and interstitial fluid. Neuroscientists in the past millennium have steadily identified the several different fluid environments in the brain and spine that interact in a synchronized harmonious manner to assure a healthy microenvironment required for optimal neuroglial function. Neuroanatomists and biochemists have provided an incredible wealth of evidence revealing the anatomy of perivascular spaces, meninges and glia and their role in drainage of neuronal waste products. Human studies have been limited due to the restricted availability of noninvasive imaging modalities that can provide a high spatiotemporal depiction of the brain neurofluids. Therefore, animal studies have been key in advancing our knowledge of the temporal and spatial dynamics of fluids, for example, by injecting tracers with different molecular weights. Such studies have sparked interest to identify possible disruptions to neurofluids dynamics in human diseases such as small vessel disease, cerebral amyloid angiopathy, and dementia. However, key differences between rodent and human physiology should be considered when extrapolating these findings to understand the human brain. An increasing armamentarium of noninvasive MRI techniques is being built to identify markers of altered drainage pathways. During the three-day workshop organized by the International Society of Magnetic Resonance in Medicine that was held in Rome in September 2022, several of these concepts were discussed by a distinguished international faculty to lay the basis of what is known and where we still lack evidence. We envision that in the next decade, MRI will allow imaging of the physiology of neurofluid dynamics and drainage pathways in the human brain to identify true pathological processes underlying disease and to discover new avenues for early diagnoses and treatments including drug delivery. Evidence level: 1 Technical Efficacy: Stage 3.
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Affiliation(s)
- Nivedita Agarwal
- Neuroradiology Unit, Scientific Institute IRCCS E. Medea, Bosisio Parini, Italy
| | - Laura D. Lewis
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, USA
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Lydiane Hirschler
- C.J. Gorter MRI Center, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Leonardo Rivera Rivera
- Wisconsin Alzheimer’s Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Shinji Naganawa
- Department of Radiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | | | - Geir Ringstad
- Department of Radiology, Oslo University Hospital Rikshospitalet, Oslo, Norway
- Department of Geriatrics and Internal Medicine, Sorlandet Hospital, Arendal, Norway
| | - Marijan Klarica
- Department of Pharmacology and Croatian Institute of Brain Research, University of Zagreb School of Medicine, Zagreb, Croatia
| | - Joanna Wardlaw
- Centre for Clinical Brain Sciences and UK Dementia Research Institute Centre, University of Edinburgh, Edinburgh, UK
| | - Costantino Iadecola
- Department of Pharmacology and Croatian Institute of Brain Research, University of Zagreb School of Medicine, Zagreb, Croatia
| | - Cheryl Hawkes
- Biomedical and Life Sciences, Lancaster University, Lancaster, UK
| | | | - Jack Wells
- UCL Centre for Advanced Biomedical Imaging, University College of London, London, UK
| | - Erik N.T.P. Bakker
- Biomedical Engineering and Physics, Amsterdam UMC, University of Amsterdam, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | | | - Lynne Bilston
- Neuroscience Research Australia and UNSW Medicine, Sydney, Australia
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, New York, USA
- Center for Translational Neuromedicine, University of Copenhagen, Copenhagen, Denmark
| | - Yuki Mori
- Center for Translational Neuromedicine, University of Copenhagen, Copenhagen, Denmark
| | - Marcus Stoodley
- Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, Australia
- Department of Neurosurgery, Macquarie University Hospital, Sydney, Australia
| | - Noam Alperin
- Department of Radiology and Biomedical Engineering, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Mony de Leon
- Weil Cornell Medicine, Department of Radiology, Brain Health Imaging Institute, New York City, New York, USA
| | - Matthias J.P. van Osch
- C.J. Gorter MRI Center, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
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8
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Cserép C, Pósfai B, Szabadits E, Dénes Á. Contactomics of Microglia and Intercellular Communication. ADVANCES IN NEUROBIOLOGY 2024; 37:135-149. [PMID: 39207690 DOI: 10.1007/978-3-031-55529-9_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
Microglia represent the main immunocompetent cell type in the parenchyma of the brain and the spinal cord, with roles extending way beyond their immune functions. While emerging data show the pivotal role of microglia in brain development, brain health and brain diseases, the exact mechanisms through which microglia contribute to complex neuroimmune interactions are still largely unclear. Understanding the communication between microglia and other cells represents an important cornerstone of these interactions, which may provide novel opportunities for therapeutic interventions in neurological or psychiatric disorders. As such, in line with studying the effects of the numerous soluble mediators that influence neuroimmune processes, attention on physical interactions between microglia and other cells in the CNS has increased substantially in recent years. In this chapter, we briefly summarize the latest literature on "microglial contactomics" and its functional implications in health and disease.
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Affiliation(s)
- Csaba Cserép
- "Momentum" Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
| | - Balázs Pósfai
- "Momentum" Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
| | - Eszter Szabadits
- "Momentum" Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
| | - Ádám Dénes
- "Momentum" Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary.
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9
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Sosa MJ, Shih AY, Bonney SK. The elusive brain perivascular fibroblast: a potential role in vascular stability and homeostasis. Front Cardiovasc Med 2023; 10:1283434. [PMID: 38075961 PMCID: PMC10704358 DOI: 10.3389/fcvm.2023.1283434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Accepted: 11/10/2023] [Indexed: 01/09/2024] Open
Abstract
In the brain, perivascular fibroblasts (PVFs) reside within the perivascular spaces (PVSs) of arterioles and large venules, however their physiological and pathophysiological roles remain largely unknown. PVFs express numerous extracellular matrix proteins that are found in the basement membrane and PVS surrounding large diameter vessels. PVFs are sandwiched between the mural cell layer and astrocytic endfeet, where they are poised to interact with mural cells, perivascular macrophages, and astrocytes. We draw connections between the more well-studied PVF pro-fibrotic response in ischemic injury and the less understood thickening of the vascular wall and enlargement of the PVS described in dementia and neurodegenerative diseases. We postulate that PVFs may be responsible for stability and homeostasis of the brain vasculature, and may also contribute to changes within the PVS during disease.
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Affiliation(s)
- Maria J. Sosa
- Center for Developmental Biology and Regenerative Medicine, Seattle Children’s Research Institute, Seattle, WA, United States
| | - Andy Y. Shih
- Center for Developmental Biology and Regenerative Medicine, Seattle Children’s Research Institute, Seattle, WA, United States
- Department of Pediatrics, University of Washington, Seattle, WA, United States
- Department of Bioengineering, University of Washington, Seattle, WA, United States
| | - Stephanie K. Bonney
- Center for Developmental Biology and Regenerative Medicine, Seattle Children’s Research Institute, Seattle, WA, United States
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10
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Doney E, Bernatchez R, Clavet-Fournier V, Dudek KA, Dion-Albert L, Lavoie-Cardinal F, Menard C. Characterizing the blood-brain barrier and gut barrier with super-resolution imaging: opportunities and challenges. NEUROPHOTONICS 2023; 10:044410. [PMID: 37799760 PMCID: PMC10548114 DOI: 10.1117/1.nph.10.4.044410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 09/21/2023] [Accepted: 09/25/2023] [Indexed: 10/07/2023]
Abstract
Brain and gut barriers have been receiving increasing attention in health and diseases including in psychiatry. Recent studies have highlighted changes in the blood-brain barrier and gut barrier structural properties, notably a loss of tight junctions, leading to hyperpermeability, passage of inflammatory mediators, stress vulnerability, and the development of depressive behaviors. To decipher the cellular processes actively contributing to brain and gut barrier function in health and disease, scientists can take advantage of neurophotonic tools and recent advances in super-resolution microscopy techniques to complement traditional imaging approaches like confocal and electron microscopy. Here, we summarize the challenges, pros, and cons of these innovative approaches, hoping that a growing number of scientists will integrate them in their study design exploring barrier-related properties and mechanisms.
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Affiliation(s)
- Ellen Doney
- Université Laval, Department of Psychiatry and Neuroscience, Faculty of Medicine, Quebec City, Québec, Canada
- CERVO Brain Research Center, Québec City, Québec, Canada
| | - Renaud Bernatchez
- CERVO Brain Research Center, Québec City, Québec, Canada
- Institute for Intelligence and Data, Québec City, Québec, Canada
| | | | - Katarzyna A. Dudek
- Université Laval, Department of Psychiatry and Neuroscience, Faculty of Medicine, Quebec City, Québec, Canada
- CERVO Brain Research Center, Québec City, Québec, Canada
| | - Laurence Dion-Albert
- Université Laval, Department of Psychiatry and Neuroscience, Faculty of Medicine, Quebec City, Québec, Canada
- CERVO Brain Research Center, Québec City, Québec, Canada
| | - Flavie Lavoie-Cardinal
- Université Laval, Department of Psychiatry and Neuroscience, Faculty of Medicine, Quebec City, Québec, Canada
- CERVO Brain Research Center, Québec City, Québec, Canada
- Institute for Intelligence and Data, Québec City, Québec, Canada
| | - Caroline Menard
- Université Laval, Department of Psychiatry and Neuroscience, Faculty of Medicine, Quebec City, Québec, Canada
- CERVO Brain Research Center, Québec City, Québec, Canada
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11
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Morris GP, Foster CG, Courtney J, Collins JM, Cashion JM, Brown LS, Howells DW, DeLuca GC, Canty AJ, King AE, Ziebell JM, Sutherland BA. Microglia directly associate with pericytes in the central nervous system. Glia 2023; 71:1847-1869. [PMID: 36994950 PMCID: PMC10952742 DOI: 10.1002/glia.24371] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 03/15/2023] [Accepted: 03/20/2023] [Indexed: 03/31/2023]
Abstract
Cerebral blood flow (CBF) is important for the maintenance of brain function and its dysregulation has been implicated in Alzheimer's disease (AD). Microglia associations with capillaries suggest they may play a role in the regulation of CBF or the blood-brain-barrier (BBB). We explored the relationship between microglia and pericytes, a vessel-resident cell type that has a major role in the control of CBF and maintenance of the BBB, discovering a spatially distinct subset of microglia that closely associate with pericytes. We termed these pericyte-associated microglia (PEM). PEM are present throughout the brain and spinal cord in NG2DsRed × CX3 CR1+/GFP mice, and in the human frontal cortex. Using in vivo two-photon microscopy, we found microglia residing adjacent to pericytes at all levels of the capillary tree and found they can maintain their position for at least 28 days. PEM can associate with pericytes lacking astroglial endfeet coverage and capillary vessel width is increased beneath pericytes with or without an associated PEM, but capillary width decreases if a pericyte loses a PEM. Deletion of the microglia fractalkine receptor (CX3 CR1) did not disrupt the association between pericytes and PEM. Finally, we found the proportion of microglia that are PEM declines in the superior frontal gyrus in AD. In summary, we identify microglia that specifically associate with pericytes and find these are reduced in number in AD, which may be a novel mechanism contributing to vascular dysfunction in neurodegenerative diseases.
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Affiliation(s)
- Gary P. Morris
- Tasmanian School of Medicine, College of Health and MedicineUniversity of TasmaniaHobartTasmaniaAustralia
| | - Catherine G. Foster
- Tasmanian School of Medicine, College of Health and MedicineUniversity of TasmaniaHobartTasmaniaAustralia
| | - Jo‐Maree Courtney
- Tasmanian School of Medicine, College of Health and MedicineUniversity of TasmaniaHobartTasmaniaAustralia
| | - Jessica M. Collins
- Wicking Dementia Research and Education Centre, College of Health and MedicineUniversity of TasmaniaHobartTasmaniaAustralia
| | - Jake M. Cashion
- Tasmanian School of Medicine, College of Health and MedicineUniversity of TasmaniaHobartTasmaniaAustralia
| | - Lachlan S. Brown
- Tasmanian School of Medicine, College of Health and MedicineUniversity of TasmaniaHobartTasmaniaAustralia
| | - David W. Howells
- Tasmanian School of Medicine, College of Health and MedicineUniversity of TasmaniaHobartTasmaniaAustralia
| | - Gabriele C. DeLuca
- Nuffield Department of Clinical NeurosciencesUniversity of OxfordOxfordUK
| | - Alison J. Canty
- Wicking Dementia Research and Education Centre, College of Health and MedicineUniversity of TasmaniaHobartTasmaniaAustralia
- Global Brain Health InstituteTrinity CollegeDublinIreland
| | - Anna E. King
- Wicking Dementia Research and Education Centre, College of Health and MedicineUniversity of TasmaniaHobartTasmaniaAustralia
| | - Jenna M. Ziebell
- Wicking Dementia Research and Education Centre, College of Health and MedicineUniversity of TasmaniaHobartTasmaniaAustralia
| | - Brad A. Sutherland
- Tasmanian School of Medicine, College of Health and MedicineUniversity of TasmaniaHobartTasmaniaAustralia
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12
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Shetti AU, Ramakrishnan A, Romanova L, Li W, Vo K, Volety I, Ratnayake I, Stephen T, Minshall RD, Cologna SM, Lazarov O. Reduced endothelial caveolin-1 underlies deficits in brain insulin signalling in type 2 diabetes. Brain 2023; 146:3014-3028. [PMID: 36731883 PMCID: PMC10316766 DOI: 10.1093/brain/awad028] [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: 08/05/2022] [Revised: 01/07/2023] [Accepted: 01/17/2023] [Indexed: 02/04/2023] Open
Abstract
Patients with type 2 diabetes exhibit severe impairments in insulin signalling in the brain and are five times more likely to develop Alzheimer's disease. However, what leads to these impairments is not fully understood. Here, we show reduced expression of endothelial cell caveolin-1 (Cav-1) in the db/db (Leprdb) mouse model of type 2 diabetes. This reduction correlated with alterations in insulin receptor expression and signalling in brain microvessels as well as brain parenchyma. These findings were recapitulated in the brains of endothelial cell-specific Cav-1 knock-out (Tie2Cre; Cav-1fl/fl) mice. Lack of Cav-1 in endothelial cells led to reduced response to insulin as well as reduced insulin uptake. Furthermore, we observed that Cav-1 was necessary for the stabilization of insulin receptors in lipid rafts. Interactome analysis revealed that insulin receptor interacts with Cav-1 and caveolae-associated proteins, insulin-degrading enzyme and the tight junction protein Zonula Occludence-1 in brain endothelial cells. Restoration of Cav-1 in Cav-1 knock-out brain endothelial cells rescued insulin receptor expression and localization. Overall, these results suggest that Cav-1 regulates insulin signalling and uptake by brain endothelial cells by modulating IR-α and IR-β localization and function in lipid rafts. Furthermore, depletion of endothelial cell-specific Cav-1 and the resulting impairment in insulin transport leads to alteration in insulin signalling in the brain parenchyma of type 2 diabetics.
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Affiliation(s)
- Aashutosh U Shetti
- Department of Anatomy and Cell Biology, College of Medicine, The University of Illinois Chicago, Chicago, IL 60612, USA
| | - Abhirami Ramakrishnan
- Department of Anatomy and Cell Biology, College of Medicine, The University of Illinois Chicago, Chicago, IL 60612, USA
| | - Liudmila Romanova
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612, USA
| | - Wenping Li
- Department of Chemistry, College of Liberal Arts and Sciences, The University of Illinois Chicago, Chicago, IL 60612, USA
| | - Khanh Vo
- Department of Anatomy and Cell Biology, College of Medicine, The University of Illinois Chicago, Chicago, IL 60612, USA
| | - Ipsita Volety
- Department of Anatomy and Cell Biology, College of Medicine, The University of Illinois Chicago, Chicago, IL 60612, USA
| | - Ishara Ratnayake
- Electron Microscopy Core, Research Resource Center, The University of Illinois Chicago, Chicago, IL 60612, USA
| | - Terilyn Stephen
- Department of Anatomy and Cell Biology, College of Medicine, The University of Illinois Chicago, Chicago, IL 60612, USA
| | - Richard D Minshall
- Department of Pharmacology and Regenerative Medicine, College of Medicine, The University of Illinois Chicago, Chicago, IL 60612, USA
- Department of Anesthesiology, College of Medicine, The University of Illinois Chicago, Chicago, IL 60612, USA
| | - Stephanie M Cologna
- Department of Chemistry, College of Liberal Arts and Sciences, The University of Illinois Chicago, Chicago, IL 60612, USA
| | - Orly Lazarov
- Department of Anatomy and Cell Biology, College of Medicine, The University of Illinois Chicago, Chicago, IL 60612, USA
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13
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Waxman S, Quinn M, Donahue C, Falo LD, Sun D, Jakobs TC, Sigal IA. Individual astrocyte morphology in the collagenous lamina cribrosa revealed by multicolor DiOlistic labeling. Exp Eye Res 2023; 230:109458. [PMID: 36965593 PMCID: PMC10152998 DOI: 10.1016/j.exer.2023.109458] [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: 12/21/2022] [Revised: 03/17/2023] [Accepted: 03/20/2023] [Indexed: 03/27/2023]
Abstract
Astrocytes in the lamina region of the optic nerve head play vital roles in supporting retinal ganglion cell axon health. In glaucoma, these astrocytes are implicated as early responders to stressors, undergoing characteristic changes in cell function as well as cell morphology. Much of what is currently known about individual lamina astrocyte morphology has been learned from rodent models which lack a defining feature of the human optic nerve head, the collagenous lamina cribrosa (LC). Current methods available for evaluation of collagenous LC astrocyte morphology have significant shortcomings. We aimed to evaluate Multicolor DiOlistic labeling (MuDi) as an approach to reveal individual astrocyte morphologies across the collagenous LC. Gold microcarriers were coated with all combinations of three fluorescent cell membrane dyes, DiI, DiD, and DiO, for a total of seven dye combinations. Microcarriers were delivered to 150 μm-thick coronal vibratome slices through the LC of pig, sheep, goat, and monkey eyes via MuDi. Labeled tissues were imaged with confocal and second harmonic generation microscopy to visualize dyed cells and LC collagenous beams, respectively. GFAP labeling of DiOlistically-labeled cells with astrocyte morphologies was used to investigate cell identity. 3D models of astrocytes were created from confocal image stacks for quantification of morphological features. DiOlistic labeling revealed fine details of LC astrocyte morphologies including somas, primary branches, higher-order branches, and end-feet. Labeled cells with astrocyte morphologies were GFAP+. Astrocytes were visible across seven distinct color channels, allowing high labeling density while still distinguishing individual cells from their neighbors. MuDi was capable of revealing tens to hundreds of collagenous LC astrocytes, in situ, with a single application. 3D astrocyte models allowed automated quantification of morphological features including branch number, length, thickness, hierarchy, and straightness as well as Sholl analysis. MuDi labeling provides an opportunity to investigate morphologies of collagenous LC astrocytes, providing both qualitative and quantitative detail, in healthy tissues. This approach may open doors for research of glaucoma, where astrocyte morphological alterations are thought to coincide with key functional changes related to disease progression.
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Affiliation(s)
- Susannah Waxman
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Marissa Quinn
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Cara Donahue
- Department of Dermatology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Louis D Falo
- Department of Dermatology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Daniel Sun
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Tatjana C Jakobs
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Ian A Sigal
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA; Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA.
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14
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Sargent SM, Bonney SK, Li Y, Stamenkovic S, Takeno M, Coelho-Santos V, Shih AY. Endothelial structure contributes to heterogeneity in brain capillary diameter. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.26.538503. [PMID: 37163126 PMCID: PMC10168366 DOI: 10.1101/2023.04.26.538503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The high metabolic demand of brain tissue is supported by a constant supply of blood through dense microvascular networks. Capillaries are the smallest class of vessels and vary in diameter between ∼2 to 5 μm in the brain. This diameter range plays a significant role in the optimization of blood flow resistance, blood cell distribution, and oxygen extraction. The control of capillary diameter has largely been ascribed to pericyte contractility, but it remains unclear if endothelial wall architecture also contributes to capillary diameter heterogeneity. Here, we use public, large-scale volume electron microscopy data from mouse cortex (MICrONS Explorer, Cortical MM^3) to examine how endothelial cell number, endothelial cell thickness, and pericyte coverage relates to microvascular lumen size. We find that transitional vessels near the penetrating arteriole and ascending venule are composed of 2 to 5 interlocked endothelial cells, while the numerous capillary segments intervening these zones are composed of either 1 or 2 endothelial cells, with roughly equal proportions. The luminal area and diameter is on average slightly larger with capillary segments composed of 2 interlocked endothelial cells versus 1 endothelial cell. However, this difference is insufficient to explain the full range of capillary diameters seen in vivo. This suggests that both endothelial structure and other influences, such as pericyte tone, contribute to the basal diameter and optimized perfusion of brain capillaries.
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15
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Koch T, Vinje V, Mardal KA. Estimates of the permeability of extra-cellular pathways through the astrocyte endfoot sheath. Fluids Barriers CNS 2023; 20:20. [PMID: 36941607 PMCID: PMC10026447 DOI: 10.1186/s12987-023-00421-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 03/07/2023] [Indexed: 03/23/2023] Open
Abstract
BACKGROUND Astrocyte endfoot processes are believed to cover all micro-vessels in the brain cortex and may play a significant role in fluid and substance transport into and out of the brain parenchyma. Detailed fluid mechanical models of diffusive and advective transport in the brain are promising tools to investigate theories of transport. METHODS We derive theoretical estimates of astrocyte endfoot sheath permeability for advective and diffusive transport and its variation in microvascular networks from mouse brain cortex. The networks are based on recently published experimental data and generated endfoot patterns are based on Voronoi tessellations of the perivascular surface. We estimate corrections for projection errors in previously published data. RESULTS We provide structural-functional relationships between vessel radius and resistance that can be directly used in flow and transport simulations. We estimate endfoot sheath filtration coefficients in the range [Formula: see text] to [Formula: see text], diffusion membrane coefficients for small solutes in the range [Formula: see text] to [Formula: see text], and gap area fractions in the range 0.2-0.6%, based on a inter-endfoot gap width of 20 nm. CONCLUSIONS The astrocyte endfoot sheath surrounding microvessels forms a secondary barrier to extra-cellular transport, separating the extra-cellular space of the parenchyma and the perivascular space outside the endothelial layer. The filtration and membrane diffusion coefficients of the endfoot sheath are estimated to be an order of magnitude lower than those of the extra-cellular matrix while being two orders of magnitude higher than those of the vessel wall.
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Affiliation(s)
- Timo Koch
- Department of Mathematics, University of Oslo, Postboks 1053 Blindern, 0316 Oslo, Norway
- Simula Research Laboratory, Kristian Augusts gate 23, 0164 Oslo, Norway
| | - Vegard Vinje
- Simula Research Laboratory, Kristian Augusts gate 23, 0164 Oslo, Norway
| | - Kent-André Mardal
- Department of Mathematics, University of Oslo, Postboks 1053 Blindern, 0316 Oslo, Norway
- Simula Research Laboratory, Kristian Augusts gate 23, 0164 Oslo, Norway
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16
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Malong L, Napoli I, Casal G, White IJ, Stierli S, Vaughan A, Cattin AL, Burden JJ, Hng KI, Bossio A, Flanagan A, Zhao HT, Lloyd AC. Characterization of the structure and control of the blood-nerve barrier identifies avenues for therapeutic delivery. Dev Cell 2023; 58:174-191.e8. [PMID: 36706755 DOI: 10.1016/j.devcel.2023.01.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 10/26/2022] [Accepted: 01/04/2023] [Indexed: 01/27/2023]
Abstract
The blood barriers of the nervous system protect neural environments but can hinder therapeutic accessibility. The blood-brain barrier (BBB) is well characterized, consisting of endothelial cells with specialized tight junctions and low levels of transcytosis, properties conferred by contacting pericytes and astrocytes. In contrast, the blood-nerve barrier (BNB) of the peripheral nervous system is poorly defined. Here, we characterize the structure of the mammalian BNB, identify the processes that confer barrier function, and demonstrate how the barrier can be opened in response to injury. The homeostatic BNB is leakier than the BBB, which we show is due to higher levels of transcytosis. However, the barrier is reinforced by macrophages that specifically engulf leaked materials, identifying a role for resident macrophages as an important component of the BNB. Finally, we demonstrate the exploitation of these processes to effectively deliver RNA-targeting therapeutics to peripheral nerves, indicating new treatment approaches for nervous system pathologies.
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Affiliation(s)
- Liza Malong
- UCL Laboratory for Molecular Cell Biology and UCL Cancer Institute, University College London, Gower Street, London, WC1E 6BT, UK
| | - Ilaria Napoli
- UCL Laboratory for Molecular Cell Biology and UCL Cancer Institute, University College London, Gower Street, London, WC1E 6BT, UK
| | - Giulia Casal
- UCL Laboratory for Molecular Cell Biology and UCL Cancer Institute, University College London, Gower Street, London, WC1E 6BT, UK
| | - Ian J White
- UCL Laboratory for Molecular Cell Biology and UCL Cancer Institute, University College London, Gower Street, London, WC1E 6BT, UK
| | - Salome Stierli
- UCL Laboratory for Molecular Cell Biology and UCL Cancer Institute, University College London, Gower Street, London, WC1E 6BT, UK
| | - Andrew Vaughan
- UCL Laboratory for Molecular Cell Biology and UCL Cancer Institute, University College London, Gower Street, London, WC1E 6BT, UK
| | - Anne-Laure Cattin
- UCL Laboratory for Molecular Cell Biology and UCL Cancer Institute, University College London, Gower Street, London, WC1E 6BT, UK
| | - Jemima J Burden
- UCL Laboratory for Molecular Cell Biology and UCL Cancer Institute, University College London, Gower Street, London, WC1E 6BT, UK
| | - Keng I Hng
- UCL Laboratory for Molecular Cell Biology and UCL Cancer Institute, University College London, Gower Street, London, WC1E 6BT, UK
| | - Alessandro Bossio
- UCL Laboratory for Molecular Cell Biology and UCL Cancer Institute, University College London, Gower Street, London, WC1E 6BT, UK
| | - Adrienne Flanagan
- UCL Laboratory for Molecular Cell Biology and UCL Cancer Institute, University College London, Gower Street, London, WC1E 6BT, UK
| | - Hien T Zhao
- IONIS, 2855 Gazelle Court, Carlsbad, CA 92010, USA
| | - Alison C Lloyd
- UCL Laboratory for Molecular Cell Biology and UCL Cancer Institute, University College London, Gower Street, London, WC1E 6BT, UK.
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17
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Sargent SM, Bonney SK, Li Y, Stamenkovic S, Takeno MM, Coelho-Santos V, Shih AY. Endothelial structure contributes to heterogeneity in brain capillary diameter. VASCULAR BIOLOGY (BRISTOL, ENGLAND) 2023; 5:e230010. [PMID: 37582180 PMCID: PMC10503221 DOI: 10.1530/vb-23-0010] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Accepted: 08/15/2023] [Indexed: 08/17/2023]
Abstract
The high metabolic demand of brain tissue is supported by a constant supply of blood flow through dense microvascular networks. Capillaries are the smallest class of vessels in the brain and their lumens vary in diameter between ~2 and 5 μm. This diameter range plays a significant role in optimizing blood flow resistance, blood cell distribution, and oxygen extraction. The control of capillary diameter has largely been ascribed to pericyte contractility, but it remains unclear if the architecture of the endothelial wall also contributes to capillary diameter. Here, we use public, large-scale volume electron microscopy data from mouse cortex (MICrONS Explorer, Cortical mm3) to examine how endothelial cell number, endothelial cell thickness, and pericyte coverage relates to microvascular lumen size. We find that transitional vessels near the penetrating arteriole and ascending venule are composed of two to six interlocked endothelial cells, while the capillaries intervening these zones are composed of either one or two endothelial cells, with roughly equal proportions. The luminal area and diameter are on average slightly larger with capillary segments composed of two interlocked endothelial cells vs one endothelial cell. However, this difference is insufficient to explain the full range of capillary diameters seen in vivo. This suggests that both endothelial structure and other influences, including pericyte tone, contribute to the basal diameter and optimized perfusion of brain capillaries.
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Affiliation(s)
- Sheridan M Sargent
- Neuroscience Graduate Program, University of Washington, Seattle, Washington, USA
| | - Stephanie K Bonney
- Center for Developmental Biology and Regenerative Medicine, Seattle Children’s Research Institute, Seattle, Washington, USA
| | - Yuandong Li
- Center for Developmental Biology and Regenerative Medicine, Seattle Children’s Research Institute, Seattle, Washington, USA
| | - Stefan Stamenkovic
- Center for Developmental Biology and Regenerative Medicine, Seattle Children’s Research Institute, Seattle, Washington, USA
| | - Marc M Takeno
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Vanessa Coelho-Santos
- Coimbra Institute for Biomedical Imaging and Translational Research, University of Coimbra, Portugal
- Institute of Nuclear Sciences Applied to Health, University of Coimbra, Portugal
| | - Andy Y Shih
- Neuroscience Graduate Program, University of Washington, Seattle, Washington, USA
- Center for Developmental Biology and Regenerative Medicine, Seattle Children’s Research Institute, Seattle, Washington, USA
- Department of Pediatrics, University of Washington, Seattle, Washington, USA
- Department of Bioengineering, University of Washington, Seattle, Washington, USA
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18
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Grubb S. Ultrastructure of precapillary sphincters and the neurovascular unit. VASCULAR BIOLOGY (BRISTOL, ENGLAND) 2023; 5:e230011. [PMID: 37855433 PMCID: PMC10762554 DOI: 10.1530/vb-23-0011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 10/09/2023] [Indexed: 10/20/2023]
Abstract
Neurons communicate with vasculature to regulate blood flow in the brain, a process maintained by the neurovascular unit (NVU). This interaction, termed neurovascular coupling, is believed to involve astrocytes or molecules capable of traversing the astrocytic endfeet. The precise mechanism, however, remains elusive. Using large 3D electron microscopy datasets, we can now study the entire NVU in context of vascular hierarchy. This study presents evidence supporting the role of precapillary sphincters as a nexus for neurovascular coupling and endothelial transcytosis. It also highlights the role of fibroblast-synthesized collagen in fortifying first-order capillaries. Furthermore, I demonstrate how astrocytic endfeet establish a barrier for fluid flow and reveal that the cortex's microvasculature is semicircled by an unexpected arrangement of parenchymal neuronal processes around penetrating arterioles and arterial-end capillaries in both mouse and human brains. These discoveries offer insights into the NVU's structure and its operational mechanisms, potentially aiding researchers in devising new strategies for preserving cognitive function and promoting healthy aging.
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Affiliation(s)
- Søren Grubb
- Department of Neuroscience and Center for Translational Neuromedicine, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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19
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Abdelazim H, Payne LB, Nolan K, Paralkar K, Bradley V, Kanodia R, Gude R, Ward R, Monavarfeshani A, Fox MA, Chappell JC. Pericyte heterogeneity identified by 3D ultrastructural analysis of the microvessel wall. Front Physiol 2022; 13:1016382. [PMID: 36589416 PMCID: PMC9800988 DOI: 10.3389/fphys.2022.1016382] [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: 08/10/2022] [Accepted: 12/05/2022] [Indexed: 12/23/2022] Open
Abstract
Confident identification of pericytes (PCs) remains an obstacle in the field, as a single molecular marker for these unique perivascular cells remains elusive. Adding to this challenge is the recent appreciation that PC populations may be heterogeneous, displaying a range of morphologies within capillary networks. We found additional support on the ultrastructural level for the classification of these PC subtypes-"thin-strand" (TSP), mesh (MP), and ensheathing (EP)-based on distinct morphological characteristics. Interestingly, we also found several examples of another cell type, likely a vascular smooth muscle cell, in a medial layer between endothelial cells (ECs) and pericytes (PCs) harboring characteristics of the ensheathing type. A conserved feature across the different PC subtypes was the presence of extracellular matrix (ECM) surrounding the vascular unit and distributed in between neighboring cells. The thickness of this vascular basement membrane was remarkably consistent depending on its location, but never strayed beyond a range of 150-300 nm unless thinned to facilitate closer proximity of neighboring cells (suggesting direct contact). The density of PC-EC contact points ("peg-and-socket" structures) was another distinguishing feature across the different PC subtypes, as were the apparent contact locations between vascular cells and brain parenchymal cells. In addition to this thinning, the extracellular matrix (ECM) surrounding EPs displayed another unique configuration in the form of extensions that emitted out radially into the surrounding parenchyma. Knowledge of the origin and function of these structures is still emerging, but their appearance suggests the potential for being mechanical elements and/or perhaps signaling nodes via embedded molecular cues. Overall, this unique ultrastructural perspective provides new insights into PC heterogeneity and the presence of medial cells within the microvessel wall, the consideration of extracellular matrix (ECM) coverage as another PC identification criteria, and unique extracellular matrix (ECM) configurations (i.e., radial extensions) that may reveal additional aspects of PC heterogeneity.
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Affiliation(s)
- Hanaa Abdelazim
- Fralin Biomedical Research Institute (FBRI) at Virginia Tech-Carilion (VTC), Roanoke, VA, United States,FBRI Center for Vascular and Heart Research, Roanoke, VA, United States
| | - Laura Beth Payne
- Fralin Biomedical Research Institute (FBRI) at Virginia Tech-Carilion (VTC), Roanoke, VA, United States,FBRI Center for Vascular and Heart Research, Roanoke, VA, United States
| | - Kyle Nolan
- Virginia Tech Carilion School of Medicine, Roanoke, VA, United States
| | - Karan Paralkar
- Fralin Biomedical Research Institute (FBRI) at Virginia Tech-Carilion (VTC), Roanoke, VA, United States
| | - Vanessa Bradley
- Fralin Biomedical Research Institute (FBRI) at Virginia Tech-Carilion (VTC), Roanoke, VA, United States
| | - Ronak Kanodia
- Fralin Biomedical Research Institute (FBRI) at Virginia Tech-Carilion (VTC), Roanoke, VA, United States
| | - Rosalie Gude
- Fralin Biomedical Research Institute (FBRI) at Virginia Tech-Carilion (VTC), Roanoke, VA, United States
| | - Rachael Ward
- Fralin Biomedical Research Institute (FBRI) at Virginia Tech-Carilion (VTC), Roanoke, VA, United States
| | - Aboozar Monavarfeshani
- Fralin Biomedical Research Institute (FBRI) at Virginia Tech-Carilion (VTC), Roanoke, VA, United States
| | - Michael A. Fox
- Fralin Biomedical Research Institute (FBRI) at Virginia Tech-Carilion (VTC), Roanoke, VA, United States,FBRI Center for Neurobiology, Roanoke, VA, United States,School of Neuroscience, Virginia Tech, Blacksburg, VA, United States
| | - John C. Chappell
- Fralin Biomedical Research Institute (FBRI) at Virginia Tech-Carilion (VTC), Roanoke, VA, United States,FBRI Center for Vascular and Heart Research, Roanoke, VA, United States,Virginia Tech Carilion School of Medicine, Roanoke, VA, United States,Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA, United States,*Correspondence: John C. Chappell,
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20
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Reciprocal Interactions between Oligodendrocyte Precursor Cells and the Neurovascular Unit in Health and Disease. Cells 2022; 11:cells11121954. [PMID: 35741083 PMCID: PMC9221698 DOI: 10.3390/cells11121954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 06/02/2022] [Accepted: 06/14/2022] [Indexed: 12/04/2022] Open
Abstract
Oligodendrocyte precursor cells (OPCs) are mostly known for their capability to differentiate into oligodendrocytes and myelinate axons. However, they have been observed to frequently interact with cells of the neurovascular unit during development, homeostasis, and under pathological conditions. The functional consequences of these interactions are largely unclear, but are increasingly studied. Although OPCs appear to be a rather homogenous cell population in the central nervous system (CNS), they present with an enormous potential to adapt to their microenvironment. In this review, it is summarized what is known about the various roles of OPC-vascular interactions, and the circumstances under which they have been observed.
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