1
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Abello J, Yin Y, Zhao Y, Maurer J, Lee J, Bodell C, Clevenger AJ, Burton Z, Goeckel ME, Lin M, Grainger S, Halabi CM, Raghavan SA, Sah R, Stratman AN. Endothelial cell Piezo1 promotes vascular smooth muscle cell differentiation on large arteries. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.11.598539. [PMID: 38915529 PMCID: PMC11195244 DOI: 10.1101/2024.06.11.598539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
Vascular stabilization is a mechanosensitive process, in part driven by blood flow. Here, we demonstrate the involvement of the mechanosensitive ion channel, Piezo1, in promoting arterial accumulation of vascular smooth muscle cells (vSMCs) during zebrafish development. Using a series of small molecule antagonists or agonists to temporally regulate Piezo1 activity, we identified a role for the Piezo1 channel in regulating klf2a levels and altered targeting of vSMCs between arteries and veins. Increasing Piezo1 activity suppressed klf2a and increased vSMC association with the cardinal vein, while inhibition of Piezo1 activity increased klf2a levels and decreased vSMC association with arteries. We supported the small molecule data with in vivo genetic suppression of piezo1 and 2 in zebrafish, resulting in loss of transgelin+ vSMCs on the dorsal aorta. Further, endothelial cell (EC)-specific Piezo1 knockout in mice was sufficient to decrease vSMC accumulation along the descending dorsal aorta during development, thus phenocopying our zebrafish data, and supporting functional conservation of Piezo1 in mammals. To determine mechanism, we used in vitro modeling assays to demonstrate that differential sensing of pulsatile versus laminar flow forces across endothelial cells changes the expression of mural cell differentiation genes. Together, our findings suggest a crucial role for EC Piezo1 in sensing force within large arteries to mediate mural cell differentiation and stabilization of the arterial vasculature.
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Affiliation(s)
- Javier Abello
- Department of Cell Biology and Physiology, Washington University in St. Louis School of Medicine, St. Louis, MO, USA
| | - Ying Yin
- Department of Cell Biology and Physiology, Washington University in St. Louis School of Medicine, St. Louis, MO, USA
| | - Yonghui Zhao
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO, USA
| | - Josh Maurer
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO, USA
| | - Jihui Lee
- Department of Cell Biology and Physiology, Washington University in St. Louis School of Medicine, St. Louis, MO, USA
| | - Cherokee Bodell
- Department of Cell Biology and Physiology, Washington University in St. Louis School of Medicine, St. Louis, MO, USA
| | - Abigail J. Clevenger
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas, USA
| | - Zarek Burton
- Department of Cell Biology and Physiology, Washington University in St. Louis School of Medicine, St. Louis, MO, USA
| | - Megan E. Goeckel
- Department of Cell Biology and Physiology, Washington University in St. Louis School of Medicine, St. Louis, MO, USA
| | - Michelle Lin
- Department of Pediatrics, Washington University School of Medicine, St. Louis, MO, USA
| | - Stephanie Grainger
- Department of Cell Biology, Van Andel Research Institute, Grand Rapids, Michigan, USA
| | - Carmen M. Halabi
- Department of Pediatrics, Washington University School of Medicine, St. Louis, MO, USA
| | - Shreya A. Raghavan
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas, USA
| | - Rajan Sah
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO, USA
- Center for Cardiovascular Research, Washington University, St Louis, MO, USA
| | - Amber N. Stratman
- Department of Cell Biology and Physiology, Washington University in St. Louis School of Medicine, St. Louis, MO, USA
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2
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Martinez TE, Mayilsamy K, Mohapatra SS, Mohapatra S. Modulation of Paracellular Permeability in SARS-CoV-2 Blood-to-Brain Transcytosis. Viruses 2024; 16:785. [PMID: 38793666 PMCID: PMC11126142 DOI: 10.3390/v16050785] [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: 03/26/2024] [Revised: 04/24/2024] [Accepted: 05/08/2024] [Indexed: 05/26/2024] Open
Abstract
SARS-CoV-2 primarily infects the lungs via the ACE2 receptor but also other organs including the kidneys, the gastrointestinal tract, the heart, and the skin. SARS-CoV-2 also infects the brain, but the hematogenous route of viral entry to the brain is still not fully characterized. Understanding how SARS-CoV-2 traverses the blood-brain barrier (BBB) as well as how it affects the molecular functions of the BBB are unclear. In this study, we investigated the roles of the receptors ACE2 and DPP4 in the SARS-CoV-2 infection of the discrete cellular components of a transwell BBB model comprising HUVECs, astrocytes, and pericytes. Our results demonstrate that direct infection on the BBB model does not modulate paracellular permeability. Also, our results show that SARS-CoV-2 utilizes clathrin and caveolin-mediated endocytosis to traverse the BBB, resulting in the direct infection of the brain side of the BBB model with a minimal endothelial infection. In conclusion, the BBB is susceptible to SARS-CoV-2 infection in multiple ways, including the direct infection of endothelium, astrocytes, and pericytes involving ACE2 and/or DPP4 and the blood-to-brain transcytosis, which is an event that does not require the presence of host receptors.
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Affiliation(s)
- Taylor E Martinez
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
- James A Haley VA Hospital, Tampa, FL 33612, USA
| | - Karthick Mayilsamy
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
- James A Haley VA Hospital, Tampa, FL 33612, USA
| | - Shyam S Mohapatra
- James A Haley VA Hospital, Tampa, FL 33612, USA
- Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
| | - Subhra Mohapatra
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
- James A Haley VA Hospital, Tampa, FL 33612, USA
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3
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van Noorden CJ, Yetkin-Arik B, Serrano Martinez P, Bakker N, van Breest Smallenburg ME, Schlingemann RO, Klaassen I, Majc B, Habic A, Bogataj U, Galun SK, Vittori M, Erdani Kreft M, Novak M, Breznik B, Hira VV. New Insights in ATP Synthesis as Therapeutic Target in Cancer and Angiogenic Ocular Diseases. J Histochem Cytochem 2024; 72:329-352. [PMID: 38733294 PMCID: PMC11107438 DOI: 10.1369/00221554241249515] [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: 12/05/2023] [Accepted: 04/01/2024] [Indexed: 05/13/2024] Open
Abstract
Lactate and ATP formation by aerobic glycolysis, the Warburg effect, is considered a hallmark of cancer. During angiogenesis in non-cancerous tissue, proliferating stalk endothelial cells (ECs) also produce lactate and ATP by aerobic glycolysis. In fact, all proliferating cells, both non-cancer and cancer cells, need lactate for the biosynthesis of building blocks for cell growth and tissue expansion. Moreover, both non-proliferating cancer stem cells in tumors and leader tip ECs during angiogenesis rely on glycolysis for pyruvate production, which is used for ATP synthesis in mitochondria through oxidative phosphorylation (OXPHOS). Therefore, aerobic glycolysis is not a specific hallmark of cancer but rather a hallmark of proliferating cells and limits its utility in cancer therapy. However, local treatment of angiogenic eye conditions with inhibitors of glycolysis may be a safe therapeutic option that warrants experimental investigation. Most types of cells in the eye such as photoreceptors and pericytes use OXPHOS for ATP production, whereas proliferating angiogenic stalk ECs rely on glycolysis for lactate and ATP production. (J Histochem Cytochem XX.XXX-XXX, XXXX).
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Affiliation(s)
- Cornelis J.F. van Noorden
- Department of Genetic Toxicology and Cancer Biology, National Institute of Biology, Ljubljana, Slovenia
- Ocular Angiogenesis Group, Amsterdam University Medical Center Location University of Amsterdam, Amsterdam, The Netherlands
| | - Bahar Yetkin-Arik
- Department of Pediatric Pulmonology, Wilhelmina Children’s Hospital, University Medical Center Utrecht, Utrecht, The Netherlands
- Regenerative Medicine Center Utrecht, University Medical Center Utrecht, Utrecht, The Netherlands
- Centre for Living Technologies, Alliance TU/e, WUR, UU, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Paola Serrano Martinez
- Ocular Angiogenesis Group, Amsterdam University Medical Center Location University of Amsterdam, Amsterdam, The Netherlands
| | - Noëlle Bakker
- Ocular Angiogenesis Group, Amsterdam University Medical Center Location University of Amsterdam, Amsterdam, The Netherlands
| | | | - Reinier O. Schlingemann
- Ocular Angiogenesis Group, Amsterdam University Medical Center Location University of Amsterdam, Amsterdam, The Netherlands
- Department of Ophthalmology, Amsterdam University Medical Center Location University of Amsterdam, Amsterdam, The Netherlands
- Department of Ophthalmology, Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, University of Lausanne, Lausanne, Switzerland
| | - Ingeborg Klaassen
- Ocular Angiogenesis Group, Amsterdam University Medical Center Location University of Amsterdam, Amsterdam, The Netherlands
| | - Bernarda Majc
- Department of Genetic Toxicology and Cancer Biology, National Institute of Biology, Ljubljana, Slovenia
| | - Anamarija Habic
- Department of Genetic Toxicology and Cancer Biology, National Institute of Biology, Ljubljana, Slovenia
- Jozef Stefan Postgraduate School, Ljubljana, Slovenia
| | - Urban Bogataj
- Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - S. Katrin Galun
- Department of Genetic Toxicology and Cancer Biology, National Institute of Biology, Ljubljana, Slovenia
| | - Milos Vittori
- Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Mateja Erdani Kreft
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Metka Novak
- Department of Genetic Toxicology and Cancer Biology, National Institute of Biology, Ljubljana, Slovenia
| | - Barbara Breznik
- Department of Genetic Toxicology and Cancer Biology, National Institute of Biology, Ljubljana, Slovenia
| | - Vashendriya V.V. Hira
- Department of Genetic Toxicology and Cancer Biology, National Institute of Biology, Ljubljana, Slovenia
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4
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Longden TA, Lederer WJ. Electro-metabolic signaling. J Gen Physiol 2024; 156:e202313451. [PMID: 38197953 PMCID: PMC10783436 DOI: 10.1085/jgp.202313451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 10/27/2023] [Accepted: 12/14/2023] [Indexed: 01/11/2024] Open
Abstract
Precise matching of energy substrate delivery to local metabolic needs is essential for the health and function of all tissues. Here, we outline a mechanistic framework for understanding this critical process, which we refer to as electro-metabolic signaling (EMS). All tissues exhibit changes in metabolism over varying spatiotemporal scales and have widely varying energetic needs and reserves. We propose that across tissues, common signatures of elevated metabolism or increases in energy substrate usage that exceed key local thresholds rapidly engage mechanisms that generate hyperpolarizing electrical signals in capillaries that then relax contractile elements throughout the vasculature to quickly adjust blood flow to meet changing needs. The attendant increase in energy substrate delivery serves to meet local metabolic requirements and thus avoids a mismatch in supply and demand and prevents metabolic stress. We discuss in detail key examples of EMS that our laboratories have discovered in the brain and the heart, and we outline potential further EMS mechanisms operating in tissues such as skeletal muscle, pancreas, and kidney. We suggest that the energy imbalance evoked by EMS uncoupling may be central to cellular dysfunction from which the hallmarks of aging and metabolic diseases emerge and may lead to generalized organ failure states-such as diverse flavors of heart failure and dementia. Understanding and manipulating EMS may be key to preventing or reversing these dysfunctions.
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Affiliation(s)
- Thomas A. Longden
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
- Laboratory of Neurovascular Interactions, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - W. Jonathan Lederer
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
- Laboratory of Molecular Cardiology, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA
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5
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You TY, Dong Q, Cui M. Emerging Links between Cerebral Blood Flow Regulation and Cognitive Decline: A Role for Brain Microvascular Pericytes. Aging Dis 2023:AD.2022.1204. [PMID: 37163446 PMCID: PMC10389833 DOI: 10.14336/ad.2022.1204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Accepted: 12/04/2022] [Indexed: 05/12/2023] Open
Abstract
Cognitive impairment associated with vascular etiology has been of considerable interest in the development of dementia. Recent studies have started to uncover cerebral blood flow deficits in initiating cognitive deterioration. Brain microvascular pericytes, the only type of contractile cells in capillaries, are involved in the precise modulation of vascular hemodynamics due to their ability to regulate resistance in the capillaries. They exhibit potential in maintaining the capillary network geometry and basal vascular tone. In addition, pericytes can facilitate better blood flow supply in response to neurovascular coupling. Their dysfunction is thought to disturb cerebral blood flow causing metabolic imbalances or structural injuries, leading to consequent cognitive decline. In this review, we summarize the characteristics of microvascular pericytes in brain blood flow regulation and outline the framework of a two-hit hypothesis in cognitive decline, where we emphasize how pericytes serve as targets of cerebral blood flow dysregulation that occurs with neurological challenges, ranging from genetic factors, aging, and pathological proteins to ischemic stress.
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Affiliation(s)
- Tong-Yao You
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
| | - Qiang Dong
- Department of Neurology, Huashan Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
- National Center for Neurological Disorders, Huashan Hospital, Fudan University, Shanghai, China
| | - Mei Cui
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
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6
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Alarcon-Martinez L, Shiga Y, Villafranca-Baughman D, Cueva Vargas JL, Vidal Paredes IA, Quintero H, Fortune B, Danesh-Meyer H, Di Polo A. Neurovascular dysfunction in glaucoma. Prog Retin Eye Res 2023; 97:101217. [PMID: 37778617 DOI: 10.1016/j.preteyeres.2023.101217] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 09/23/2023] [Accepted: 09/25/2023] [Indexed: 10/03/2023]
Abstract
Retinal ganglion cells, the neurons that die in glaucoma, are endowed with a high metabolism requiring optimal provision of oxygen and nutrients to sustain their activity. The timely regulation of blood flow is, therefore, essential to supply firing neurons in active areas with the oxygen and glucose they need for energy. Many glaucoma patients suffer from vascular deficits including reduced blood flow, impaired autoregulation, neurovascular coupling dysfunction, and blood-retina/brain-barrier breakdown. These processes are tightly regulated by a community of cells known as the neurovascular unit comprising neurons, endothelial cells, pericytes, Müller cells, astrocytes, and microglia. In this review, the neurovascular unit takes center stage as we examine the ability of its members to regulate neurovascular interactions and how their function might be altered during glaucomatous stress. Pericytes receive special attention based on recent data demonstrating their key role in the regulation of neurovascular coupling in physiological and pathological conditions. Of particular interest is the discovery and characterization of tunneling nanotubes, thin actin-based conduits that connect distal pericytes, which play essential roles in the complex spatial and temporal distribution of blood within the retinal capillary network. We discuss cellular and molecular mechanisms of neurovascular interactions and their pathophysiological implications, while highlighting opportunities to develop strategies for vascular protection and regeneration to improve functional outcomes in glaucoma.
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Affiliation(s)
- Luis Alarcon-Martinez
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada; Centre for Eye Research Australia, University of Melbourne, Melbourne, Australia
| | - Yukihiro Shiga
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Deborah Villafranca-Baughman
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Jorge L Cueva Vargas
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Isaac A Vidal Paredes
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Heberto Quintero
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Brad Fortune
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Healthy, Portland, OR, USA
| | - Helen Danesh-Meyer
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Adriana Di Polo
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada.
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7
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Karlupia N, Schalek RL, Wu Y, Meirovitch Y, Wei D, Charney AW, Kopell BH, Lichtman JW. Immersion Fixation and Staining of Multicubic Millimeter Volumes for Electron Microscopy-Based Connectomics of Human Brain Biopsies. Biol Psychiatry 2023; 94:352-360. [PMID: 36740206 PMCID: PMC10397365 DOI: 10.1016/j.biopsych.2023.01.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Revised: 01/25/2023] [Accepted: 01/27/2023] [Indexed: 02/05/2023]
Abstract
Connectomics allows mapping of cells and their circuits at the nanometer scale in volumes of approximately 1 mm3. Given that the human cerebral cortex can be 3 mm in thickness, larger volumes are required. Larger-volume circuit reconstructions of human brain are limited by 1) the availability of fresh biopsies; 2) the need for excellent preservation of ultrastructure, including extracellular space; and 3) the requirement of uniform staining throughout the sample, among other technical challenges. Cerebral cortical samples from neurosurgical patients are available owing to lead placement for deep brain stimulation. Described here is an immersion fixation, heavy metal staining, and tissue processing method that consistently provides excellent ultrastructure throughout human and rodent surgical brain samples of volumes 2 × 2 × 2 mm3 and up to 37 mm3 with one dimension ≤2 mm. This method should allow synapse-level circuit analysis in samples from patients with psychiatric and neurologic disorders.
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Affiliation(s)
- Neha Karlupia
- Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, Massachusetts.
| | - Richard L Schalek
- Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, Massachusetts
| | - Yuelong Wu
- Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, Massachusetts
| | - Yaron Meirovitch
- Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, Massachusetts
| | - Donglai Wei
- Department of Computer Science, Boston College, Boston, Massachusetts
| | | | - Brian H Kopell
- Center for Neuromodulation, Department of Neurosurgery, The Icahn School of Medicine, Mount Sinai, New York, New York
| | - Jeff W Lichtman
- Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, Massachusetts.
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8
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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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9
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Menaceur C, Hachani J, Dib S, Duban-Deweer S, Karamanos Y, Shimizu F, Kanda T, Gosselet F, Fenart L, Saint-Pol J. Highlighting In Vitro the Role of Brain-like Endothelial Cells on the Maturation and Metabolism of Brain Pericytes by SWATH Proteomics. Cells 2023; 12:cells12071010. [PMID: 37048083 PMCID: PMC10093307 DOI: 10.3390/cells12071010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 03/17/2023] [Accepted: 03/22/2023] [Indexed: 03/29/2023] Open
Abstract
Within the neurovascular unit, brain pericytes (BPs) are of major importance for the induction and maintenance of the properties of the blood-brain barrier (BBB) carried by the brain microvessel endothelial cells (ECs). Throughout barriergenesis, ECs take advantage of soluble elements or contact with BPs to maintain BBB integrity and the regulation of their cellular homeostasis. However, very few studies have focused on the role of ECs in the maturation of BPs. The aim of this study is to shed light on the proteome of BPs solocultured (hBP-solo) or cocultured with ECs (hBP-coc) to model the human BBB in a non-contact manner. We first generated protein libraries for each condition and identified 2233 proteins in hBP-solo versus 2492 in hBP-coc and 2035 common proteins. We performed a quantification of the enriched proteins in each condition by sequential window acquisition of all theoretical mass spectra (SWATH) analysis. We found 51 proteins enriched in hBP-solo related to cell proliferation, contractility, adhesion and extracellular matrix element production, a protein pattern related to an immature cell. In contrast, 90 proteins are enriched in hBP-coc associated with a reduction in contractile activities as observed in vivo in ‘mature’ BPs, and a significant gain in different metabolic functions, particularly related to mitochondrial activities and sterol metabolism. This study highlights that BPs take advantage of ECs during barriergenesis to make a metabolic switch in favor of BBB homeostasis in vitro.
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10
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Wälchli T, Bisschop J, Carmeliet P, Zadeh G, Monnier PP, De Bock K, Radovanovic I. Shaping the brain vasculature in development and disease in the single-cell era. Nat Rev Neurosci 2023; 24:271-298. [PMID: 36941369 PMCID: PMC10026800 DOI: 10.1038/s41583-023-00684-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/06/2023] [Indexed: 03/23/2023]
Abstract
The CNS critically relies on the formation and proper function of its vasculature during development, adult homeostasis and disease. Angiogenesis - the formation of new blood vessels - is highly active during brain development, enters almost complete quiescence in the healthy adult brain and is reactivated in vascular-dependent brain pathologies such as brain vascular malformations and brain tumours. Despite major advances in the understanding of the cellular and molecular mechanisms driving angiogenesis in peripheral tissues, developmental signalling pathways orchestrating angiogenic processes in the healthy and the diseased CNS remain incompletely understood. Molecular signalling pathways of the 'neurovascular link' defining common mechanisms of nerve and vessel wiring have emerged as crucial regulators of peripheral vascular growth, but their relevance for angiogenesis in brain development and disease remains largely unexplored. Here we review the current knowledge of general and CNS-specific mechanisms of angiogenesis during brain development and in brain vascular malformations and brain tumours, including how key molecular signalling pathways are reactivated in vascular-dependent diseases. We also discuss how these topics can be studied in the single-cell multi-omics era.
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Affiliation(s)
- Thomas Wälchli
- Group of CNS Angiogenesis and Neurovascular Link, Neuroscience Center Zurich, and Division of Neurosurgery, University and University Hospital Zurich, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland.
- Division of Neurosurgery, University Hospital Zurich, Zurich, Switzerland.
- Group of Brain Vasculature and Perivascular Niche, Division of Experimental and Translational Neuroscience, Krembil Brain Institute, Krembil Research Institute, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, ON, Canada.
- Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, Toronto, ON, Canada.
| | - Jeroen Bisschop
- Group of CNS Angiogenesis and Neurovascular Link, Neuroscience Center Zurich, and Division of Neurosurgery, University and University Hospital Zurich, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
- Division of Neurosurgery, University Hospital Zurich, Zurich, Switzerland
- Group of Brain Vasculature and Perivascular Niche, Division of Experimental and Translational Neuroscience, Krembil Brain Institute, Krembil Research Institute, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, ON, Canada
- Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, Toronto, ON, Canada
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Peter Carmeliet
- Laboratory of Angiogenesis and Vascular Metabolism, Center for Cancer Biology, VIB & Department of Oncology, KU Leuven, Leuven, Belgium
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, People's Republic of China
- Laboratory of Angiogenesis and Vascular Heterogeneity, Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Gelareh Zadeh
- Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, Toronto, ON, Canada
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada
| | - Philippe P Monnier
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
- Donald K. Johnson Research Institute, Krembil Research Institute, Krembil Discovery Tower, Toronto, ON, Canada
- Department of Ophthalmology and Vision Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Katrien De Bock
- Laboratory of Exercise and Health, Department of Health Science and Technology, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
| | - Ivan Radovanovic
- Group of Brain Vasculature and Perivascular Niche, Division of Experimental and Translational Neuroscience, Krembil Brain Institute, Krembil Research Institute, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, ON, Canada
- Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, Toronto, ON, Canada
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11
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Pericytes in the tumor microenvironment. Cancer Lett 2023; 556:216074. [PMID: 36682706 DOI: 10.1016/j.canlet.2023.216074] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 01/10/2023] [Accepted: 01/19/2023] [Indexed: 01/21/2023]
Abstract
Pericytes are a type of mural cell located between the endothelial cells of capillaries and the basement membrane, which function to regulate the capillary vasomotor and maintain normal microcirculation of local tissues and organs and have been identified as a significant component in the tumor microenvironment (TME). Pericytes have various interactions with different components of the TME, such as constituting the pre-metastatic niche, promoting the growth of cancer cells and drug resistance through paracrine activity, and inducing M2 macrophage polarization. While changes in the TME can affect the number, phenotype, and molecular markers of pericytes. For example, pericyte detachment from endothelial cells in the TME facilitates tumor cells in situ to invade the circulating blood and is beneficial to local capillary basement membrane enzymatic hydrolysis and endothelial cell proliferation and budding, which contribute to tumor angiogenesis and metastasis. In this review, we discuss the emerging role of pericytes in the TME, and tumor treatment related to pericytes. This review aimed to provide a more comprehensive understanding of the function of pericytes and the relationship between pericytes and tumors and to provide ideas for the treatment and prevention of malignant tumors.
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12
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The Active Role of Pericytes During Neuroinflammation in the Adult Brain. Cell Mol Neurobiol 2023; 43:525-541. [PMID: 35195811 DOI: 10.1007/s10571-022-01208-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 02/13/2022] [Indexed: 12/11/2022]
Abstract
Microvessels in the central nervous system (CNS) have one of the highest populations of pericytes, indicating their crucial role in maintaining homeostasis. Pericytes are heterogeneous cells located around brain microvessels; they present three different morphologies along the CNS vascular tree: ensheathing, mesh, and thin-strand pericytes. At the arteriole-capillary transition ensheathing pericytes are found, while mesh and thin-strand pericytes are located at capillary beds. Brain pericytes are essential for the establishment and maintenance of the blood-brain barrier, which restricts the passage of soluble and potentially toxic molecules from the circulatory system to the brain parenchyma. Pericytes play a key role in regulating local inflammation at the CNS. Pericytes can respond differentially, depending on the degree of inflammation, by secreting a set of neurotrophic factors to promote cell survival and regeneration, or by potentiating inflammation through the release of inflammatory mediators (e.g., cytokines and chemokines), and the overexpression of cell adhesion molecules. Under inflammatory conditions, pericytes may regulate immune cell trafficking to the CNS and play a role in perpetuating local inflammation. In this review, we describe pericyte responses during acute and chronic neuroinflammation.
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13
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Lochhead JJ, Williams EI, Reddell ES, Dorn E, Ronaldson PT, Davis TP. High Resolution Multiplex Confocal Imaging of the Neurovascular Unit in Health and Experimental Ischemic Stroke. Cells 2023; 12:645. [PMID: 36831312 PMCID: PMC9954836 DOI: 10.3390/cells12040645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 10/31/2022] [Accepted: 02/14/2023] [Indexed: 02/19/2023] Open
Abstract
The neurovascular unit (NVU) is an anatomical group of cells that establishes the blood-brain barrier (BBB) and coordinates cerebral blood flow in association with neuronal function. In cerebral gray matter, cellular constituents of the NVU include endothelial cells and associated pericytes, astrocytes, neurons, and microglia. Dysfunction of the NVU is a common feature of diseases that affect the CNS, such as ischemic stroke. High-level evaluation of these NVU changes requires the use of imaging modalities that can enable the visualization of various cell types under disease conditions. In this study, we applied our confocal microscopy strategy using commercially available labeling reagents to, for the first time, simultaneously investigate associations between endothelial cells, the vascular basal lamina, pericytes, microglia, astrocytes and/or astrocyte end-feet, and neurites in both healthy and ischemic brain tissue. This allowed us to demonstrate ischemia-induced astrocyte activation, neurite loss, and microglial migration toward blood vessels in a single confocal image. Furthermore, our labeling cocktail enabled a precise quantification of changes in neurites and astrocyte reactivity, thereby showing the relationship between different NVU cellular constituents in healthy and diseased brain tissue. The application of our imaging approach for the simultaneous visualization of multiple NVU cell types provides an enhanced understanding of NVU function and pathology, a state-of-the-art advancement that will facilitate the development of more effective treatment strategies for diseases of the CNS that exhibit neurovascular dysfunction, such as ischemic stroke.
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Affiliation(s)
- Jeffrey J. Lochhead
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA
| | - Erica I. Williams
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA
| | - Elizabeth S. Reddell
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA
| | - Emma Dorn
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA
| | - Patrick T. Ronaldson
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, AZ 85721, USA
| | - Thomas P. Davis
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, AZ 85721, USA
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14
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Abstract
Pericytes, attached to the surface of capillaries, play an important role in regulating local blood flow. Using optogenetic tools and genetically encoded reporters in conjunction with confocal and multiphoton imaging techniques, the 3D structure, anatomical organization, and physiology of pericytes have recently been the subject of detailed examination. This work has revealed novel functions of pericytes and morphological features such as tunneling nanotubes in brain and tunneling microtubes in heart. Here, we discuss the state of our current understanding of the roles of pericytes in blood flow control in brain and heart, where functions may differ due to the distinct spatiotemporal metabolic requirements of these tissues. We also outline the novel concept of electro-metabolic signaling, a universal mechanistic framework that links tissue metabolic state with blood flow regulation by pericytes and vascular smooth muscle cells, with capillary KATP and Kir2.1 channels as primary sensors. Finally, we present major unresolved questions and outline how they can be addressed.
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Affiliation(s)
- Thomas A Longden
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA; ,
- Laboratory of Neurovascular Interactions, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Guiling Zhao
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA; ,
- Laboratory of Molecular Cardiology, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Ashwini Hariharan
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA; ,
- Laboratory of Neurovascular Interactions, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - W Jonathan Lederer
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA; ,
- Laboratory of Molecular Cardiology, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland, USA
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15
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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: 10] [Impact Index Per Article: 10.0] [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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16
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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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17
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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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18
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Sano T, Nakajima T, Senda KA, Nakano S, Yamato M, Ikeda Y, Zeng H, Kawabe JI, Matsunaga YT. Image-based crosstalk analysis of cell-cell interactions during sprouting angiogenesis using blood-vessel-on-a-chip. Stem Cell Res Ther 2022; 13:532. [PMID: 36575469 PMCID: PMC9795717 DOI: 10.1186/s13287-022-03223-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 12/15/2022] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Sprouting angiogenesis is an important mechanism for morphogenetic phenomena, including organ development, wound healing, and tissue regeneration. In regenerative medicine, therapeutic angiogenesis is a clinical solution for recovery from ischemic diseases. Mesenchymal stem cells (MSCs) have been clinically used given their pro-angiogenic effects. MSCs are reported to promote angiogenesis by differentiating into pericytes or other vascular cells or through cell-cell communication using multiple protein-protein interactions. However, how MSCs physically contact and move around ECs to keep the sprouting angiogenesis active remains unknown. METHODS We proposed a novel framework of EC-MSC crosstalk analysis using human umbilical vein endothelial cells (HUVECs) and MSCs obtained from mice subcutaneous adipose tissue on a 3D in vitro model, microvessel-on-a-chip, which allows cell-to-tissue level study. The microvessels were fabricated and cultured for 10 days in a collagen matrix where MSCs were embedded. RESULTS Immunofluorescence imaging using a confocal laser microscope showed that MSCs smoothed the surface of the microvessel and elongated the angiogenic sprouts by binding to the microvessel's specific microstructures. Additionally, three-dimensional modeling of HUVEC-MSC intersections revealed that MSCs were selectively located around protrusions or roots of angiogenic sprouts, whose surface curvature was excessively low or high, respectively. CONCLUSIONS The combination of our microvessel-on-a-chip system for 3D co-culture and image-based crosstalk analysis demonstrated that MSCs are selectively localized to concave-convex surfaces on scaffold structures and that they are responsible for the activation and stabilization of capillary vessels.
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Affiliation(s)
- Takanori Sano
- grid.26999.3d0000 0001 2151 536XInstitute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8505 Japan
| | - Tadaaki Nakajima
- grid.26999.3d0000 0001 2151 536XInstitute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8505 Japan ,grid.268441.d0000 0001 1033 6139Department of Science, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama, Kanagawa 236-0027 Japan
| | - Koharu Alicia Senda
- Hiroo Gakuen Junior and Senior High School, 5-1-14 Minami Azabu, Minato-ku, Tokyo, 106-0047 Japan
| | - Shizuka Nakano
- grid.26999.3d0000 0001 2151 536XInstitute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8505 Japan
| | - Mizuho Yamato
- grid.26999.3d0000 0001 2151 536XInstitute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8505 Japan
| | - Yukinori Ikeda
- grid.26999.3d0000 0001 2151 536XInstitute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8505 Japan
| | - Hedele Zeng
- grid.26999.3d0000 0001 2151 536XInstitute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8505 Japan
| | - Jun-ichi Kawabe
- grid.252427.40000 0000 8638 2724Department of Biochemistry, Asahikawa Medical University, 2-1-1 Midorigaoka-higashi, Asahikawa, Hokkaido 078-8510 Japan
| | - Yukiko T. Matsunaga
- grid.26999.3d0000 0001 2151 536XInstitute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8505 Japan
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19
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Hariharan A, Robertson CD, Garcia DCG, Longden TA. Brain capillary pericytes are metabolic sentinels that control blood flow through a K ATP channel-dependent energy switch. Cell Rep 2022; 41:111872. [PMID: 36577387 PMCID: PMC10187957 DOI: 10.1016/j.celrep.2022.111872] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 10/10/2022] [Accepted: 11/30/2022] [Indexed: 12/28/2022] Open
Abstract
Despite the abundance of capillary thin-strand pericytes and their proximity to neurons and glia, little is known of the contributions of these cells to the control of brain hemodynamics. We demonstrate that the pharmacological activation of thin-strand pericyte KATP channels profoundly hyperpolarizes these cells, dilates upstream penetrating arterioles and arteriole-proximate capillaries, and increases capillary blood flow. Focal stimulation of pericytes with a KATP channel agonist is sufficient to evoke this response, mediated via KIR2.1 channel-dependent retrograde propagation of hyperpolarizing signals, whereas genetic inactivation of pericyte KATP channels eliminates these effects. Critically, we show that decreasing extracellular glucose to less than 1 mM or inhibiting glucose uptake by blocking GLUT1 transporters in vivo flips a mechanistic energy switch driving rapid KATP-mediated pericyte hyperpolarization to increase local blood flow. Together, our findings recast capillary pericytes as metabolic sentinels that respond to local energy deficits by increasing blood flow to neurons to prevent energetic shortfalls.
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Affiliation(s)
- Ashwini Hariharan
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD, USA; Laboratory of Neurovascular Interactions, Center for Biomedical Engineering and Technology, School of Medicine, University of Maryland, Baltimore, MD, USA
| | - Colin D Robertson
- Department of Pharmacology, School of Medicine, University of Maryland, Baltimore, MD, USA
| | - Daniela C G Garcia
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD, USA; Laboratory of Neurovascular Interactions, Center for Biomedical Engineering and Technology, School of Medicine, University of Maryland, Baltimore, MD, USA
| | - Thomas A Longden
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD, USA; Laboratory of Neurovascular Interactions, Center for Biomedical Engineering and Technology, School of Medicine, University of Maryland, Baltimore, MD, USA.
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20
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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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21
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Murrant CL, Fletcher NM. Capillary communication: the role of capillaries in sensing the tissue environment, coordinating the microvascular, and controlling blood flow. Am J Physiol Heart Circ Physiol 2022; 323:H1019-H1036. [PMID: 36149771 DOI: 10.1152/ajpheart.00088.2022] [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: 12/14/2022]
Abstract
Historically, capillaries have been viewed as the microvascular site for flux of nutrients to cells and removal of waste products. Capillaries are the most numerous blood vessel segment within the tissue, whose vascular wall consists of only a single layer of endothelial cells and are situated within microns of each cell of the tissue, all of which optimizes capillaries for the exchange of nutrients between the blood compartment and the interstitial space of tissues. There is, however, a growing body of evidence to support that capillaries play an important role in sensing the tissue environment, coordinating microvascular network responses, and controlling blood flow. Much of our growing understanding of capillaries stems from work in skeletal muscle and more recent work in the brain, where capillaries can be stimulated by products released from cells of the tissue during increased activity and are able to communicate with upstream and downstream vascular segments, enabling capillaries to sense the activity levels of the tissue and send signals to the microvascular network to coordinate the blood flow response. This review will focus on the emerging role that capillaries play in communication between cells of the tissue and the vascular network required to direct blood flow to active cells in skeletal muscle and the brain. We will also highlight the emerging central role that disruptions in capillary communication may play in blood flow dysregulation, pathophysiology, and disease.
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Affiliation(s)
- Coral L Murrant
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Nicole M Fletcher
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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22
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Goncalves A, Antonetti DA. Transgenic animal models to explore and modulate the blood brain and blood retinal barriers of the CNS. Fluids Barriers CNS 2022; 19:86. [PMID: 36320068 PMCID: PMC9628113 DOI: 10.1186/s12987-022-00386-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 10/03/2022] [Indexed: 11/18/2022] Open
Abstract
The unique environment of the brain and retina is tightly regulated by blood-brain barrier and the blood-retinal barrier, respectively, to ensure proper neuronal function. Endothelial cells within these tissues possess distinct properties that allow for controlled passage of solutes and fluids. Pericytes, glia cells and neurons signal to endothelial cells (ECs) to form and maintain the barriers and control blood flow, helping to create the neurovascular unit. This barrier is lost in a wide range of diseases affecting the central nervous system (CNS) and retina such as brain tumors, stroke, dementia, and in the eye, diabetic retinopathy, retinal vein occlusions and age-related macular degeneration to name prominent examples. Recent studies directly link barrier changes to promotion of disease pathology and degradation of neuronal function. Understanding how these barriers form and how to restore these barriers in disease provides an important point for therapeutic intervention. This review aims to describe the fundamentals of the blood-tissue barriers of the CNS and how the use of transgenic animal models led to our current understanding of the molecular framework of these barriers. The review also highlights examples of targeting barrier properties to protect neuronal function in disease states.
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Affiliation(s)
- Andreia Goncalves
- Department of Ophthalmology and Visual Sciences, University of Michigan Kellogg Eye Center, 1000 Wall St Rm, Ann Arbor, MI, 7317, USA
| | - David A Antonetti
- Department of Ophthalmology and Visual Sciences, University of Michigan Kellogg Eye Center, 1000 Wall St Rm, Ann Arbor, MI, 7317, USA.
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23
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Edgerton-Fulton M, Ergul A. Vascular contributions to cognitive impairment/dementia in diabetes: role of endothelial cells and pericytes. Am J Physiol Cell Physiol 2022; 323:C1177-C1189. [PMID: 36036445 PMCID: PMC9576164 DOI: 10.1152/ajpcell.00072.2022] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 08/19/2022] [Accepted: 08/19/2022] [Indexed: 11/22/2022]
Abstract
Vascular contributions to cognitive impairment/dementia (VCID) are a leading cause of dementia, a known neurodegenerative disorder characterized by progressive cognitive decline. Although diabetes increases the risks of stroke and the development of cerebrovascular disease, the cellular and vascular mechanisms that lead to VCID in diabetes are yet to be determined. A growing body of research has identified that cerebrovascular cells within the neurovascular complex display an array of cellular responses that impact their survival and reparative properties, which plays a significant role in VCID development. Specifically, endothelial cells and pericytes are the primary cell types that have gained much attention in dementia-related studies due to their molecular and phenotypic heterogeneity. In this review, we will discuss the various morphological subclasses of endothelial cells and pericytes as well as their relative distribution throughout the cerebrovasculature. Furthermore, the use of diabetic and stroke animal models in preclinical studies has provided more insight into the impact of sex differences on cerebral vascularization in progressive VCID. Understanding how cellular responses and sex differences contribute to endothelial cell and pericyte survival and function will set the stage for the development of potential preventive therapies for dementia-related disorders in diabetes.
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Affiliation(s)
- Mia Edgerton-Fulton
- Ralph H. Johnson VA Medical Center, Charleston, South Carolina
- Department of Pathology & Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - Adviye Ergul
- Ralph H. Johnson VA Medical Center, Charleston, South Carolina
- Department of Pathology & Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina
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24
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Remodeling of the Neurovascular Unit Following Cerebral Ischemia and Hemorrhage. Cells 2022; 11:cells11182823. [PMID: 36139398 PMCID: PMC9496956 DOI: 10.3390/cells11182823] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 08/18/2022] [Accepted: 08/30/2022] [Indexed: 11/23/2022] Open
Abstract
Formulated as a group effort of the stroke community, the transforming concept of the neurovascular unit (NVU) depicts the structural and functional relationship between brain cells and the vascular structure. Composed of both neural and vascular elements, the NVU forms the blood-brain barrier that regulates cerebral blood flow to meet the oxygen demand of the brain in normal physiology and maintain brain homeostasis. Conversely, the dysregulation and dysfunction of the NVU is an essential pathological feature that underlies neurological disorders spanning from chronic neurodegeneration to acute cerebrovascular events such as ischemic stroke and cerebral hemorrhage, which were the focus of this review. We also discussed how common vascular risk factors of stroke predispose the NVU to pathological changes. We synthesized existing literature and first provided an overview of the basic structure and function of NVU, followed by knowledge of how these components remodel in response to ischemic stroke and brain hemorrhage. A greater understanding of the NVU dysfunction and remodeling will enable the design of targeted therapies and provide a valuable foundation for relevant research in this area.
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25
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Albargothy MJ, Azizah NN, Stewart SL, Troendle EP, Steel DHW, Curtis TM, Taggart MJ. Investigation of heterocellular features of the mouse retinal neurovascular unit by 3D electron microscopy. J Anat 2022. [PMID: 35841597 DOI: 10.1111/joa.13721] [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: 01/29/2022] [Revised: 06/06/2022] [Accepted: 06/15/2022] [Indexed: 11/26/2022] Open
Abstract
The retina has a complex structure with a diverse collection of component cells that work together to facilitate vision. The retinal capillaries supplying the nutritional requirements to the inner retina have an intricate system of neural, glial and vascular elements that interconnect to form the neurovascular unit (NVU). The retina has no autonomic nervous system and so relies on the NVU as an interdependent, physical and functional unit to alter blood flow appropriately to changes in the physiological environment. The importance of this is demonstrated by alterations in NVU function being apparent in the blinding disease diabetic retinopathy and other diseases of the retina. It is, therefore, imperative to understand the anatomy of the components of the NVU that underlie its functioning and in particular the nanoscale arrangements of its heterocellular components. However, information on this in three spatial dimensions is limited. In the present study, we utilised the technique of serial block-face scanning electron microscopy (SBF-SEM), and computational image reconstruction, to enable the first three-dimensional ultrastructural analysis of the NVU in mouse retinal capillaries. Mouse isolated retina was prepared for SBF-SEM and up to 150 serial scanning electron microscopy images (covering z-axes distances of 12-8 mm) of individual capillaries in the superficial plexus and NVU cellular components digitally aligned. Examination of the data in the x-, y- and z-planes was performed with the use of semi-automated computational image analysis tools including segmentation, 3D image reconstruction and quantitation of cell proximities. A prominent feature of the capillary arrangements in 3D was the extensive sheath-like coverage by singular pericytes. They appeared in close register to the basement membrane with which they interwove in a complex mesh-like appearance. Breaks in the basement membrane appeared to facilitate pericyte interactions with other NVU cell types. There were frequent, close (<10 nm) pericyte-endothelial interactions with direct contact points and peg-and-socket-like morphology. Macroglia typically intervened between neurons and capillary structures; however, regions were identified where neurons came into closer contact with the basement membrane. A software-generated analysis to assess the morphology of the different cellular components of the NVU, including quantifications of convexity, sphericity and cell-to-cell closeness, has enabled preliminary semi-quantitative characterisation of cell arrangements with neighbouring structures. This study presents new data on the nanoscale spatial characteristics of components of the murine retinal NVU in 3D that has implications for our understanding of structural integrity (e.g. pericyte-endothelial cell anchoring) and function (e.g. possible paracrine communication between macroglia and pericytes). It also serves as a platform to inform future studies examining changes in NVU characteristics with different biological and disease circumstances. All raw and processed image data have been deposited for public viewing.
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Affiliation(s)
- Mona J Albargothy
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Nadhira N Azizah
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Sarah L Stewart
- Wellcome Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, UK
| | - Evan P Troendle
- Wellcome Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, UK
| | - David H W Steel
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Tim M Curtis
- Wellcome Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, UK
| | - Michael J Taggart
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK
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26
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Keep RF, Jones HC, Drewes LR. Advances in brain barriers and brain fluids research in 2021: great progress in a time of adversity. Fluids Barriers CNS 2022; 19:48. [PMID: 35681151 PMCID: PMC9178944 DOI: 10.1186/s12987-022-00343-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Accepted: 05/16/2022] [Indexed: 11/10/2022] Open
Abstract
This editorial highlights advances in brain barrier and brain fluid research in 2021. It covers research on components of the blood–brain barrier, neurovascular unit and brain fluid systems; how brain barriers and brain fluid systems are impacted by neurological disorders and their role in disease progression; and advances in strategies for treating such disorders.
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Affiliation(s)
- Richard F Keep
- Department of Neurosurgery, University of Michigan, R5018 BSRB, 109 Zina Pitcher Place, Ann Arbor, MI, 48109-2200, USA.
| | | | - Lester R Drewes
- Department of Biomedical Sciences, University of Minnesota Medical School Duluth, Duluth, MN, 55812, USA
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27
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Bonney SK, Sullivan LT, Cherry TJ, Daneman R, Shih AY. Distinct features of brain perivascular fibroblasts and mural cells revealed by in vivo two-photon imaging. J Cereb Blood Flow Metab 2022; 42:966-978. [PMID: 34929105 PMCID: PMC9125487 DOI: 10.1177/0271678x211068528] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 11/11/2021] [Accepted: 11/19/2021] [Indexed: 12/04/2022]
Abstract
Perivascular fibroblasts (PVFs) are recognized for their pro-fibrotic role in many central nervous system disorders. Like mural cells, PVFs surround blood vessels and express Pdgfrβ. However, these shared attributes hinder the ability to distinguish PVFs from mural cells. We used in vivo two-photon imaging and transgenic mice with PVF-targeting promoters (Col1a1 or Col1a2) to compare the structure and distribution of PVFs and mural cells in cerebral cortex of healthy, adult mice. We show that PVFs localize to all cortical penetrating arterioles and their offshoots (arteriole-capillary transition zone), as well as the main trunk of only larger ascending venules. However, the capillary zone is devoid of PVF coverage. PVFs display short-range mobility along the vessel wall and exhibit distinct structural features (flattened somata and thin ruffled processes) not seen with smooth muscle cells or pericytes. These findings clarify that PVFs and mural cells are distinct cell types coexisting in a similar perivascular niche.
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Affiliation(s)
- Stephanie K Bonney
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA, USA
| | - Liam T Sullivan
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA, USA
| | - Timothy J Cherry
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA, USA
| | - Richard Daneman
- Departments of Neurosciences and Pharmacology, University of California San Diego, La Jolla, CA, USA
| | - Andy Y Shih
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA, USA
- Department of Pediatrics, University of Washington, Seattle, WA, USA
- Department of Bioengineering, University of Washington, Seattle, WA, USA
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28
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Nielson CD, Berthiaume AA, Bonney SK, Shih AY. In vivo Single Cell Optical Ablation of Brain Pericytes. Front Neurosci 2022; 16:900761. [PMID: 35720702 PMCID: PMC9205398 DOI: 10.3389/fnins.2022.900761] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 04/19/2022] [Indexed: 01/09/2023] Open
Abstract
Pericytes have myriad functions in cerebrovascular regulation but remain understudied in the living brain. To dissect pericyte functions in vivo, prior studies have used genetic approaches to induce global pericyte loss in the rodent brain. However, this leads to complex outcomes, making it challenging to disentangle the physiological roles of pericytes from the pathophysiological effects of their depletion. Here, we describe a protocol to optically ablate individual pericytes of the mouse cerebral cortex in vivo for fine-scale studies of pericyte function. The strategy relies on two-photon microscopy and cranial window-implanted transgenic mice with mural cell-specific expression of fluorescent proteins. Single pericyte somata are precisely targeted with pulsed infrared laser light to induce selective pericyte death, but without overt blood-brain barrier leakage. Following pericyte ablation, the changes to the local capillary network and remaining pericytes can be examined longitudinally. The approach has been used to study pericyte roles in capillary flow regulation, and the structural remodeling of pericytes involved in restoration of endothelial coverage after pericyte loss.
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Affiliation(s)
- Cara D. Nielson
- Center for Developmental Biology and Regenerative Medicine, Seattle Children’s Research Institute, Seattle, WA, United States,Graduate Program in Neuroscience, University of Washington, Seattle, WA, United States
| | - Andrée-Anne Berthiaume
- Center for Developmental Biology and Regenerative Medicine, Seattle Children’s Research Institute, Seattle, WA, United States,Department of Neuroscience, Medical University of South Carolina, Charleston, SC, United States
| | - Stephanie K. Bonney
- 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,*Correspondence: Andy Y. Shih,
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29
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Mou Y, Du Y, Zhou L, Yue J, Hu X, Liu Y, Chen S, Lin X, Zhang G, Xiao H, Dong B. Gut Microbiota Interact With the Brain Through Systemic Chronic Inflammation: Implications on Neuroinflammation, Neurodegeneration, and Aging. Front Immunol 2022; 13:796288. [PMID: 35464431 PMCID: PMC9021448 DOI: 10.3389/fimmu.2022.796288] [Citation(s) in RCA: 86] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Accepted: 02/22/2022] [Indexed: 02/05/2023] Open
Abstract
It has been noticed in recent years that the unfavorable effects of the gut microbiota could exhaust host vigor and life, yet knowledge and theory are just beginning to be established. Increasing documentation suggests that the microbiota-gut-brain axis not only impacts brain cognition and psychiatric symptoms but also precipitates neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). How the blood-brain barrier (BBB), a machinery protecting the central nervous system (CNS) from the systemic circulation, allows the risky factors derived from the gut to be translocated into the brain seems paradoxical. For the unique anatomical, histological, and immunological properties underpinning its permeable dynamics, the BBB has been regarded as a biomarker associated with neural pathogenesis. The BBB permeability of mice and rats caused by GM dysbiosis raises the question of how the GM and its metabolites change BBB permeability and causes the brain pathophysiology of neuroinflammation and neurodegeneration (NF&ND) and brain aging, a pivotal multidisciplinary field tightly associated with immune and chronic systemic inflammation. If not all, gut microbiota-induced systemic chronic inflammation (GM-SCI) mainly refers to excessive gut inflammation caused by gut mucosal immunity dysregulation, which is often influenced by dietary components and age, is produced at the interface of the intestinal barrier (IB) or exacerbated after IB disruption, initiates various common chronic diseases along its dispersal routes, and eventually impairs BBB integrity to cause NF&ND and brain aging. To illustrate the immune roles of the BBB in pathophysiology affected by inflammatory or "leaky" IB resulting from GM and their metabolites, we reviewed the selected publications, including the role of the BBB as the immune barrier, systemic chronic inflammation and inflammation influences on BBB permeability, NF&ND, and brain aging. To add depth to the bridging role of systemic chronic inflammation, a plausible mechanism indispensable for BBB corruption was highlighted; namely, BBB maintenance cues are affected by inflammatory cytokines, which may help to understand how GM and its metabolites play a major role in NF&ND and aging.
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Affiliation(s)
- Yi Mou
- Geroscience and Chronic Disease Department, The Eighth Municipal Hospital for the People, Chengdu, China
| | - Yu Du
- Department of Emergency and Critical Care Medicine, The Fourth West China Hospital, Sichuan University, Chengdu, China
| | - Lixing Zhou
- National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Jirong Yue
- National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Xianliang Hu
- Geroscience and Chronic Disease Department, The Eighth Municipal Hospital for the People, Chengdu, China
| | - Yixin Liu
- National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Sao Chen
- Geroscience and Chronic Disease Department, The Eighth Municipal Hospital for the People, Chengdu, China
| | - Xiufang Lin
- National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Gongchang Zhang
- National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Hengyi Xiao
- National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Birong Dong
- National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
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30
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Muhl L, He L, Sun Y, Andaloussi Mäe M, Pietilä R, Liu J, Genové G, Zhang L, Xie Y, Leptidis S, Mocci G, Stritt S, Osman A, Anisimov A, Hemanthakumar KA, Räsänen M, Hansson EM, Björkegren J, Vanlandewijck M, Blomgren K, Mäkinen T, Peng XR, Hu Y, Ernfors P, Arnold TD, Alitalo K, Lendahl U, Betsholtz C. The SARS-CoV-2 receptor ACE2 is expressed in mouse pericytes but not endothelial cells: Implications for COVID-19 vascular research. Stem Cell Reports 2022; 17:1089-1104. [PMID: 35452595 PMCID: PMC9022216 DOI: 10.1016/j.stemcr.2022.03.016] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 03/25/2022] [Accepted: 03/28/2022] [Indexed: 12/11/2022] Open
Abstract
Humanized mouse models and mouse-adapted SARS-CoV-2 virus are increasingly used to study COVID-19 pathogenesis, so it is important to learn where the SARS-CoV-2 receptor ACE2 is expressed. Here we mapped ACE2 expression during mouse postnatal development and in adulthood. Pericytes in the CNS, heart, and pancreas express ACE2 strongly, as do perineurial and adrenal fibroblasts, whereas endothelial cells do not at any location analyzed. In a number of other organs, pericytes do not express ACE2, including in the lung where ACE2 instead is expressed in bronchial epithelium and alveolar type II cells. The onset of ACE2 expression is organ specific: in bronchial epithelium already at birth, in brain pericytes before, and in heart pericytes after postnatal day 10.5. Establishing the vascular localization of ACE2 expression is central to correctly interpret data from modeling COVID-19 in the mouse and may shed light on the cause of vascular COVID-19 complications. Detailed Ace2/ACE2 expression patterns are reported for multiple mouse organs Vascular Ace2/ACE2 expression occurs in pericytes but not endothelial cells Ace2/ACE2 expression is organotypic and developmentally regulated Ace2/ACE2 expression in pericytes may suggest their involvement in COVID-19
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Affiliation(s)
- Lars Muhl
- Department of Medicine, Huddinge, Karolinska Institutet, Solna, Sweden
| | - Liqun He
- Department of Immunology, Genetics, and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden; Department of Neurosurgery, Tianjin Medical University General Hospital, Tianjin Neurological Institute, Key Laboratory of Post-Neuro-injury Neuro-Repair and Regeneration in Central Nervous System, Ministry of Education and Tianjin City, Tianjin 300052, China
| | - Ying Sun
- Department of Immunology, Genetics, and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
| | - Maarja Andaloussi Mäe
- Department of Immunology, Genetics, and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
| | - Riikka Pietilä
- Department of Immunology, Genetics, and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
| | - Jianping Liu
- Department of Medicine, Huddinge, Karolinska Institutet, Solna, Sweden
| | - Guillem Genové
- Department of Medicine, Huddinge, Karolinska Institutet, Solna, Sweden
| | - Lei Zhang
- Key Laboratory of Ministry of Education for Medicinal Plant Resource and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an China
| | - Yuan Xie
- Key Laboratory of Ministry of Education for Medicinal Plant Resource and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an China
| | - Stefanos Leptidis
- Department of Medicine, Huddinge, Karolinska Institutet, Solna, Sweden
| | - Giuseppe Mocci
- Department of Medicine, Huddinge, Karolinska Institutet, Solna, Sweden
| | - Simon Stritt
- Department of Immunology, Genetics, and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
| | - Ahmed Osman
- Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden
| | - Andrey Anisimov
- Wihuri Research Institute and Translational Cancer Medicine Program, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland
| | - Karthik Amudhala Hemanthakumar
- Wihuri Research Institute and Translational Cancer Medicine Program, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland
| | - Markus Räsänen
- Wihuri Research Institute and Translational Cancer Medicine Program, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland
| | - Emil M Hansson
- Department of Medicine, Huddinge, Karolinska Institutet, Solna, Sweden
| | - Johan Björkegren
- Department of Medicine, Huddinge, Karolinska Institutet, Solna, Sweden; Institute of Genomics and Multiscale Biology, Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Michael Vanlandewijck
- Department of Medicine, Huddinge, Karolinska Institutet, Solna, Sweden; Department of Immunology, Genetics, and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
| | - Klas Blomgren
- Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden; Department of Pediatric Oncology, Karolinska University Hospital, Stockholm Sweden
| | - Taija Mäkinen
- Department of Immunology, Genetics, and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
| | - Xiao-Rong Peng
- Cardiovascular, Renal and Metabolism, AstraZeneca BioPharmaceutical R&D, Gothenburg, Sweden
| | - Yizhou Hu
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Solna, Sweden
| | - Patrik Ernfors
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Solna, Sweden
| | - Thomas D Arnold
- Department of Pediatrics, University of California San Francisco, San Francisco, CA 94143, USA
| | - Kari Alitalo
- Wihuri Research Institute and Translational Cancer Medicine Program, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland
| | - Urban Lendahl
- Department of Cell and Molecular Biology, Karolinska Institutet, Solna, Sweden.
| | - Christer Betsholtz
- Department of Medicine, Huddinge, Karolinska Institutet, Solna, Sweden; Department of Immunology, Genetics, and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden.
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31
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Bonney SK, Coelho-Santos V, Huang SF, Takeno M, Kornfeld J, Keller A, Shih AY. Public Volume Electron Microscopy Data: An Essential Resource to Study the Brain Microvasculature. Front Cell Dev Biol 2022; 10:849469. [PMID: 35450291 PMCID: PMC9016339 DOI: 10.3389/fcell.2022.849469] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 02/21/2022] [Indexed: 01/09/2023] Open
Abstract
Electron microscopy is the primary approach to study ultrastructural features of the cerebrovasculature. However, 2D snapshots of a vascular bed capture only a small fraction of its complexity. Recent efforts to synaptically map neuronal circuitry using volume electron microscopy have also sampled the brain microvasculature in 3D. Here, we perform a meta-analysis of 7 data sets spanning different species and brain regions, including two data sets from the MICrONS consortium that have made efforts to segment vasculature in addition to all parenchymal cell types in mouse visual cortex. Exploration of these data have revealed rich information for detailed investigation of the cerebrovasculature. Neurovascular unit cell types (including, but not limited to, endothelial cells, mural cells, perivascular fibroblasts, microglia, and astrocytes) could be discerned across broad microvascular zones. Image contrast was sufficient to identify subcellular details, including endothelial junctions, caveolae, peg-and-socket interactions, mitochondria, Golgi cisternae, microvilli and other cellular protrusions of potential significance to vascular signaling. Additionally, non-cellular structures including the basement membrane and perivascular spaces were visible and could be traced between arterio-venous zones along the vascular wall. These explorations revealed structural features that may be important for vascular functions, such as blood-brain barrier integrity, blood flow control, brain clearance, and bioenergetics. They also identified limitations where accuracy and consistency of segmentation could be further honed by future efforts. The purpose of this article is to introduce these valuable community resources within the framework of cerebrovascular research. We do so by providing an assessment of their vascular contents, identifying features of significance for further study, and discussing next step ideas for refining vascular segmentation and analysis.
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Affiliation(s)
- Stephanie K. Bonney
- Center for Developmental Biology and Regenerative Medicine, Seattle Children’s Research Institute, Seattle, WA, United States
| | - Vanessa Coelho-Santos
- Center for Developmental Biology and Regenerative Medicine, Seattle Children’s Research Institute, Seattle, WA, United States
| | - Sheng-Fu Huang
- Department of Neurosurgery, Clinical Neuroscience Center, University Hospital Zürich, University of Zürich, Zürich, Switzerland
- Neuroscience Center Zürich, University of Zürich and ETH Zürich, Zürich, Switzerland
| | - Marc Takeno
- Allen Institute for Brain Science, Seattle, WA, United States
| | | | - Annika Keller
- Department of Neurosurgery, Clinical Neuroscience Center, University Hospital Zürich, University of Zürich, Zürich, Switzerland
- Neuroscience Center Zürich, University of Zürich and ETH Zürich, Zürich, Switzerland
- *Correspondence: Annika Keller, ; Andy Y. Shih,
| | - 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
- *Correspondence: Annika Keller, ; Andy Y. Shih,
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Hartmann DA, Coelho-Santos V, Shih AY. Pericyte Control of Blood Flow Across Microvascular Zones in the Central Nervous System. Annu Rev Physiol 2022; 84:331-354. [PMID: 34672718 PMCID: PMC10480047 DOI: 10.1146/annurev-physiol-061121-040127] [Citation(s) in RCA: 70] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The vast majority of the brain's vascular length is composed of capillaries, where our understanding of blood flow control remains incomplete. This review synthesizes current knowledge on the control of blood flow across microvascular zones by addressing issues with nomenclature and drawing on new developments from in vivo optical imaging and single-cell transcriptomics. Recent studies have highlighted important distinctions in mural cell morphology, gene expression, and contractile dynamics, which can explain observed differences in response to vasoactive mediators between arteriole, transitional, and capillary zones. Smooth muscle cells of arterioles and ensheathing pericytes of the arteriole-capillary transitional zone control large-scale, rapid changes in blood flow. In contrast, capillary pericytes downstream of the transitional zone act on slower and smaller scales and are involved in establishing resting capillary tone and flow heterogeneity. Many unresolved issues remain, including the vasoactive mediators that activate the different pericyte types in vivo, the role of pericyte-endothelial communication in conducting signals from capillaries to arterioles, and how neurological disease affects these mechanisms.
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Affiliation(s)
- David A Hartmann
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, California, USA
| | - Vanessa Coelho-Santos
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, Washington, USA;
- Department of Pediatrics, University of Washington, Seattle, Washington, USA
| | - Andy Y Shih
- 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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Menaceur C, Gosselet F, Fenart L, Saint-Pol J. The Blood-Brain Barrier, an Evolving Concept Based on Technological Advances and Cell-Cell Communications. Cells 2021; 11:cells11010133. [PMID: 35011695 PMCID: PMC8750298 DOI: 10.3390/cells11010133] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 12/27/2021] [Accepted: 12/30/2021] [Indexed: 02/07/2023] Open
Abstract
The construction of the blood–brain barrier (BBB), which is a natural barrier for maintaining brain homeostasis, is the result of a meticulous organisation in space and time of cell–cell communication processes between the endothelial cells that carry the BBB phenotype, the brain pericytes, the glial cells (mainly the astrocytes), and the neurons. The importance of these communications for the establishment, maturation and maintenance of this unique phenotype had already been suggested in the pioneering work to identify and demonstrate the BBB. As for the history of the BBB, the evolution of analytical techniques has allowed knowledge to evolve on the cell–cell communication pathways involved, as well as on the role played by the cells constituting the neurovascular unit in the maintenance of the BBB phenotype, and more particularly the brain pericytes. This review summarises the key points of the history of the BBB, from its origin to the current knowledge of its physiology, as well as the cell–cell communication pathways identified so far during its development, maintenance, and pathophysiological alteration.
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Guerin CJ, Lippens S. Correlative light and volume electron microscopy (vCLEM): How community participation can advance developing technologies. J Microsc 2021; 284:97-102. [PMID: 34476818 PMCID: PMC9291772 DOI: 10.1111/jmi.13056] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 08/31/2021] [Accepted: 08/31/2021] [Indexed: 12/28/2022]
Abstract
Correlative light and electron microscopy is a valuable tool to image samples across resolution scales and link data on structure and function. While studies using this technique have been available since the 1960s, recent developments have enabled applying these workflows to large volumes of cells and tissues. Much of the development in this area has been facilitated through the collaborative efforts of microscopists and commercial companies to bring the methods, hardware and image processing technologies needed into laboratories and core imaging facilities. This is a prime example of how what was once a niche area can be brought into the mainstream of microscopy by the efforts of imaging pioneers who push the boundaries of possibility.
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Affiliation(s)
| | - Saskia Lippens
- VIB Bio Imaging Core, VIB - Ghent University, Ghent, Belgium
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