1
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Du M, Li J, Yu S, Chen X, She Y, Lu Y, Shu H. RAGE mediates hippocampal pericyte responses and neurovascular unit lesions after TBI. Exp Neurol 2024; 380:114912. [PMID: 39097075 DOI: 10.1016/j.expneurol.2024.114912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2024] [Revised: 07/13/2024] [Accepted: 07/30/2024] [Indexed: 08/05/2024]
Abstract
Traumatic brain injury impairs brain function through various mechanisms. Recent studies have shown that alterations in pericytes in various diseases affect neurovascular function, but the effects of TBI on hippocampal pericytes remain unclear. Here, we investigated the effects of RAGE activation on pericytes after TBI using male C57BL/6 J mice. Hippocampal samples were collected at different time points within 7 days after TBI, the expression of PDGFR-β, NG2 and the HMGB1-S100B/RAGE signaling pathway was assessed by Western blotting, and the integrity of the hippocampal BBB at different time points was measured by immunofluorescence. RAGE-associated BBB damage in hippocampal pericytes occurred early after cortical impact. By culturing primary mouse brain microvascular pericytes, we determined the different effects of HMGB1-S100B on pericyte RAGE. To investigate whether RAGE blockade could protect neurological function after TBI, we reproduced the process of CCI by administering FPS-ZM1 to RAGE-/- mice. TEM images and BBB damage-related assays showed that inhibition of RAGE resulted in a significant improvement in the number of hippocampal vascular basement membranes and tight junctions and a reduction in perivascular oedema compared with those in the untreated group. In contrast, mouse behavioural testing and doublecortin staining indicated that targeting the HMGB1-S100B/RAGE axis after CCI could protect neurological function by reducing pericyte-associated BBB damage. In conclusion, the present study provides experimental evidence for the strong correlation between the pericyte HMGB1-S100B/RAGE axis and NVU damage in the hippocampus at the early stage of TBI and further demonstrates that pericyte RAGE serves as an important target for the protection of neurological function after TBI.
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Affiliation(s)
- Minghao Du
- Department of Neurosurgery, The General Hospital of Western Theater Command, College of Medicine, Southwest Jiaotong University, Chengdu 610031, Sichuan, China; Mini-Invasive Neurosurgery and Translational Medical Center, Xi'an Central Hospital, Xi'an Jiaotong University, Xi'an 710003, China
| | - Jiani Li
- Department of Gastroenterology, Xi'an Central Hospital, Xi'an Jiaotong University, Xi'an 710003, China
| | - Sixun Yu
- Department of Neurosurgery, The General Hospital of Western Theater Command, College of Medicine, Southwest Jiaotong University, Chengdu 610031, Sichuan, China
| | - Xin Chen
- Department of Neurosurgery, The General Hospital of Western Theater Command, College of Medicine, Southwest Jiaotong University, Chengdu 610031, Sichuan, China
| | - Youyu She
- Mini-Invasive Neurosurgery and Translational Medical Center, Xi'an Central Hospital, Xi'an Jiaotong University, Xi'an 710003, China
| | - Yichen Lu
- Honghui Hospital, Xi'an Jiaotong University, Xi'an, Shaanxi 710054, China.
| | - Haifeng Shu
- Department of Neurosurgery, The General Hospital of Western Theater Command, College of Medicine, Southwest Jiaotong University, Chengdu 610031, Sichuan, China.
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2
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Bonney SK, Nielson CD, Sosa MJ, Bonnar O, Shih AY. Capillary regression leads to sustained local hypoperfusion by inducing constriction of upstream transitional vessels. Proc Natl Acad Sci U S A 2024; 121:e2321021121. [PMID: 39236241 PMCID: PMC11406265 DOI: 10.1073/pnas.2321021121] [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: 12/01/2023] [Accepted: 08/07/2024] [Indexed: 09/07/2024] Open
Abstract
In the brain, a microvascular sensory web coordinates oxygen delivery to regions of neuronal activity. This involves a dense network of capillaries that send conductive signals upstream to feeding arterioles to promote vasodilation and blood flow. Although this process is critical to the metabolic supply of healthy brain tissue, it may also be a point of vulnerability in disease. Deterioration of capillary networks is a feature of many neurological disorders and injuries and how this web is engaged during vascular damage remains unknown. We performed in vivo two-photon microscopy on young adult mural cell reporter mice and induced focal capillary injuries using precise two-photon laser irradiation of single capillaries. We found that ~59% of the injuries resulted in regression of the capillary segment 7 to 14 d following injury, and the remaining repaired to reestablish blood flow within 7 d. Injuries that resulted in capillary regression induced sustained vasoconstriction in the upstream arteriole-capillary transition (ACT) zone at least 21 days postinjury in both awake and anesthetized mice. The degree of vasomotor dynamics was chronically attenuated in the ACT zone consequently reducing blood flow in the ACT zone and in secondary, uninjured downstream capillaries. These findings demonstrate how focal capillary injury and regression can impair the microvascular sensory web and contribute to cerebral hypoperfusion.
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Affiliation(s)
- Stephanie K Bonney
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA 98101
| | - Cara D Nielson
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA 98101
- Graduate Program in Neuroscience, University of Washington, Seattle, WA 98195
| | - Maria J Sosa
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA 98101
| | - Orla Bonnar
- MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02129
| | - Andy Y Shih
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA 98101
- Department of Pediatrics, University of Washington, Seattle, WA 98195
- Department of Bioengineering, University of Washington, Seattle, WA 98195
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3
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Edgerton-Fulton M, Abdul Y, Jamil S, Ergul A. Endothelin-1 (ET-1) contributes to senescence and phenotypic changes in brain pericytes in diabetes-mimicking conditions. Clin Sci (Lond) 2024; 138:1009-1022. [PMID: 39106080 DOI: 10.1042/cs20240328] [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: 02/21/2024] [Revised: 08/03/2024] [Accepted: 08/06/2024] [Indexed: 08/07/2024]
Abstract
Diabetes mediates endothelial dysfunction and increases the risk of Alzheimer's disease and related dementias. Diabetes also dysregulates the ET system. ET-1-mediated constriction of brain microvascular pericytes (BMVPCs) has been shown to contribute to brain hypoperfusion. Cellular senescence, a process that arrests the proliferation of harmful cells and instigates phenotypical changes and proinflammatory responses in endothelial cells that impact their survival and function. Thus, we hypothesized that ET-1 mediates BMVPC senescence and phenotypical changes in diabetes-like conditions. Human BMVPCs were incubated in diabetes-like conditions with or without ET-1 (1 µmol/L) for 3 and 7 days. Hydrogen peroxide (100 µmol/L H2O2) was used as a positive control for senescence and to mimic ischemic conditions. Cells were stained for senescence-associated β-galactosidase or processed for immunoblotting and quantitative real-time PCR analyses. In additional experiments, cells were stimulated with ET-1 in the presence or absence of ETA receptor antagonist BQ-123 (20 μmol/L) or ETB receptor antagonist BQ-788 (20 μmol/L). ET-1 stimulation increased β-galactosidase accumulation which was prevented by BQ-123. ET-1 also increased traditional senescence marker p16 protein and pericyte-specific senescence markers, TGFB1i1, PP1CA, and IGFBP7. Furthermore, ET-1 stimulated contractile protein α-SMA and microglial marker ostepontin in high glucose suggesting a shift toward an ensheathing or microglia-like phenotype. In conclusion, ET-1 triggers senescence, alters ETA and ETB receptors, and causes phenotypical changes in BMVPCs under diabetes-like conditions. These in vitro findings need to be further studied in vivo to establish the role of ETA receptors in the progression of pericyte senescence and phenotypical changes in VCID.
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Affiliation(s)
- Mia Edgerton-Fulton
- Department of Pathology & Laboratory Medicine, Medical University of South Carolina, Charleston, SC, U.S.A
| | - Yasir Abdul
- Department of Pathology & Laboratory Medicine, Medical University of South Carolina, Charleston, SC, U.S.A
| | - Sarah Jamil
- Department of Pathology & Laboratory Medicine, Medical University of South Carolina, Charleston, SC, U.S.A
| | - Adviye Ergul
- Department of Pathology & Laboratory Medicine, Medical University of South Carolina, Charleston, SC, U.S.A
- Ralph H Johnson VA Health Care System, Medical University of South Carolina, Charleston, SC, U.S.A
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4
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Scarpellino G, Brunetti V, Berra-Romani R, De Sarro G, Guerra G, Soda T, Moccia F. The Unexpected Role of the Endothelial Nitric Oxide Synthase at the Neurovascular Unit: Beyond the Regulation of Cerebral Blood Flow. Int J Mol Sci 2024; 25:9071. [PMID: 39201757 PMCID: PMC11354477 DOI: 10.3390/ijms25169071] [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: 07/22/2024] [Revised: 08/19/2024] [Accepted: 08/21/2024] [Indexed: 09/03/2024] Open
Abstract
Nitric oxide (NO) is a highly versatile gasotransmitter that has first been shown to regulate cardiovascular function and then to exert tight control over a much broader range of processes, including neurotransmitter release, neuronal excitability, and synaptic plasticity. Endothelial NO synthase (eNOS) is usually far from the mind of synaptic neurophysiologists, who have focused most of their attention on neuronal NO synthase (nNOS) as the primary source of NO at the neurovascular unit (NVU). Nevertheless, the available evidence suggests that eNOS could also contribute to generating the burst of NO that, serving as volume intercellular messenger, is produced in response to neuronal activity in the brain parenchyma. Herein, we review the role of eNOS in both the regulation of cerebral blood flow and of synaptic plasticity and discuss the mechanisms by which cerebrovascular endothelial cells may transduce synaptic inputs into a NO signal. We further suggest that eNOS could play a critical role in vascular-to-neuronal communication by integrating signals converging onto cerebrovascular endothelial cells from both the streaming blood and active neurons.
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Affiliation(s)
- Giorgia Scarpellino
- Laboratory of General Physiology, Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy; (G.S.); (V.B.)
| | - Valentina Brunetti
- Laboratory of General Physiology, Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy; (G.S.); (V.B.)
| | - Roberto Berra-Romani
- Department of Biomedicine, School of Medicine, Benemérita Universidad Autónoma de Puebla, Puebla 72410, Mexico;
| | - Giovambattista De Sarro
- Department of Health Sciences, University of Magna Graecia, 88100 Catanzaro, Italy; (G.D.S.); (T.S.)
| | - Germano Guerra
- Department of Medicine and Health Sciences “V. Tiberio”, University of Molise, 86100 Campobasso, Italy;
| | - Teresa Soda
- Department of Health Sciences, University of Magna Graecia, 88100 Catanzaro, Italy; (G.D.S.); (T.S.)
| | - Francesco Moccia
- Department of Medicine and Health Sciences “V. Tiberio”, University of Molise, 86100 Campobasso, Italy;
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5
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Daoud HAS, Kokoti L, Al-Karagholi MAM. K ATP channels in cerebral hemodynamics: a systematic review of preclinical and clinical studies. Front Neurol 2024; 15:1417421. [PMID: 39022739 PMCID: PMC11252034 DOI: 10.3389/fneur.2024.1417421] [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: 04/14/2024] [Accepted: 06/14/2024] [Indexed: 07/20/2024] Open
Abstract
Cumulative evidence suggests that ATP-sensitive potassium (KATP) channels act as a key regulator of cerebral blood flow (CBF). This implication seems to be complicated, since KATP channels are expressed in several vascular-related structures such as smooth muscle cells, endothelial cells and pericytes. In this systematic review, we searched PubMed and EMBASE for preclinical and clinical studies addressing the involvement of KATP channels in CBF regulation. A total of 216 studies were screened by title and abstract. Of these, 45 preclinical and 6 clinical studies were included. Preclinical data showed that KATP channel openers (KCOs) caused dilation of several cerebral arteries including pial arteries, the middle cerebral artery and basilar artery, and KATP channel inhibitor (KCI) glibenclamide, reversed the dilation. Glibenclamide affected neither the baseline CBF nor the baseline vascular tone. Endothelium removal from cerebral arterioles resulted in an impaired response to KCO/KCI. Clinical studies showed that KCOs dilated cerebral arteries and increased CBF, however, glibenclamide failed to attenuate these vascular changes. Endothelial KATP channels played a major role in CBF regulation. More studies investigating the role of KATP channels in CBF-related structures are needed to further elucidate their actual role in cerebral hemodynamics in humans. Systematic review registration: Prospero: CRD42023339278 (preclinical data) and CRD42022339152 (clinical data).
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Affiliation(s)
- Hassan Ali Suleiman Daoud
- Department of Neurology, Danish Headache Center, Copenhagen University Hospital- Rigshospitalet, Copenhagen, Denmark
| | - Lili Kokoti
- Department of Neurology, Danish Headache Center, Copenhagen University Hospital- Rigshospitalet, Copenhagen, Denmark
| | - Mohammad Al-Mahdi Al-Karagholi
- Department of Neurology, Danish Headache Center, Copenhagen University Hospital- Rigshospitalet, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Neurology, Nordsjaellands Hospital- Hilleroed, Hilleroed, Denmark
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6
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Wellman S, Forrest AM, Douglas MM, Subbaraman A, Zhang G, Kozai TDY. Dynamic changes in structure and function of brain mural cells around chronically implanted microelectrodes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.11.598494. [PMID: 38915601 PMCID: PMC11195141 DOI: 10.1101/2024.06.11.598494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
Integration of neural interfaces with minimal tissue disruption in the brain is ideal to develop robust tools that can address essential neuroscience questions and combat neurological disorders. However, implantation of intracortical devices provokes severe tissue inflammation within the brain, which requires a high metabolic demand to support a complex series of cellular events mediating tissue degeneration and wound healing. Pericytes, peri-vascular cells involved in blood-brain barrier maintenance, vascular permeability, waste clearance, and angiogenesis, have recently been implicated as potential perpetuators of neurodegeneration in brain injury and disease. While the intimate relationship between pericytes and the cortical microvasculature have been explored in other disease states, their behavior following microelectrode implantation, which is responsible for direct blood vessel disruption and dysfunction, is currently unknown. Using two-photon microscopy we observed dynamic changes in the structure and function of pericytes during implantation of a microelectrode array over a 4-week implantation period. Pericytes respond to electrode insertion through transient increases in intracellular calcium and underlying constriction of capillary vessels. Within days following the initial insertion, we observed an influx of new, proliferating pericytes which contribute to new blood vessel formation. Additionally, we discovered a potentially novel population of reactive immune cells in close proximity to the electrode-tissue interface actively engaging in encapsulation of the microelectrode array. Finally, we determined that intracellular pericyte calcium can be modulated by intracortical microstimulation in an amplitude- and frequency-dependent manner. This study provides a new perspective on the complex biological sequelae occurring the electrode-tissue interface and will foster new avenues of potential research consideration and lead to development of more advanced therapeutic interventions towards improving the biocompatibility of neural electrode technology.
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7
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Ruff CF, Juarez Anaya F, Dienel SJ, Rakymzhan A, Altamirano-Espinoza A, Couey JJ, Fukuda M, Watson AM, Su A, Fish KN, Rubio ME, Hooks BM, Ross SE, Vazquez AL. Long-range inhibitory neurons mediate cortical neurovascular coupling. Cell Rep 2024; 43:113970. [PMID: 38512868 PMCID: PMC11168451 DOI: 10.1016/j.celrep.2024.113970] [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: 06/08/2023] [Revised: 12/29/2023] [Accepted: 02/29/2024] [Indexed: 03/23/2024] Open
Abstract
To meet the high energy demands of brain function, cerebral blood flow (CBF) parallels changes in neuronal activity by a mechanism known as neurovascular coupling (NVC). However, which neurons play a role in mediating NVC is not well understood. Here, we identify in mice and humans a specific population of cortical GABAergic neurons that co-express neuronal nitric oxide synthase and tachykinin receptor 1 (Tacr1). Through whole-tissue clearing, we demonstrate that Tacr1 neurons extend local and long-range projections across functionally connected cortical areas. We show that whisker stimulation elicited Tacr1 neuron activity in the barrel cortex through feedforward excitatory pathways. Additionally, through optogenetic experiments, we demonstrate that Tacr1 neurons are instrumental in mediating CBF through the relaxation of mural cells in a similar fashion to whisker stimulation. Finally, by electron microscopy, we observe that Tacr1 processes contact astrocytic endfeet. These findings suggest that Tacr1 neurons integrate cortical activity to mediate NVC.
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Affiliation(s)
- Catherine F Ruff
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, USA
| | | | - Samuel J Dienel
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
| | - Adiya Rakymzhan
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | | | - Jonathan J Couey
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Mitsuhiro Fukuda
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Alan M Watson
- Center for Biologic Imaging, University of Pittsburgh, Pittsburgh, PA, USA
| | - Aihua Su
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Kenneth N Fish
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
| | - Maria E Rubio
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Bryan M Hooks
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Sarah E Ross
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, USA.
| | - Alberto L Vazquez
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA; Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA.
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8
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Zhang C, Shi J, Dai Y, Li X, Leng J. Progress of the study of pericytes and their potential research value in adenomyosis. Sci Prog 2024; 107:368504241257126. [PMID: 38863331 PMCID: PMC11179483 DOI: 10.1177/00368504241257126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2024]
Abstract
Pericytes (PCs) are versatile cells integral to the microcirculation wall, exhibiting specific stem cell traits. They are essential in modulating blood flow, ensuring vascular permeability, maintaining homeostasis, and aiding tissue repair process. Given their involvement in numerous disease-related pathological and physiological processes, the regulation of PCs has emerged as a focal point of research. Adenomyosis is characterized by the presence of active endometrial glands and stroma encased by an enlarged and proliferative myometrial layer, further accompanied by fibrosis and new blood vessel formation. This distinct pathological condition might be intricately linked with PCs. This article comprehensively reviews the markers associated with PCs, their contributions to angiogenesis, blood flow modulation, and fibrotic processes. Moreover, it provides a comprehensive overview of the current research on adenomyosis pathophysiology, emphasizing the potential correlation and future implications regarding PCs and the development of adenomyosis.
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Affiliation(s)
- Chenyu Zhang
- Department of Obstetrics and Gynecology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
- National Clinical Research Center for Obstetric & Gynecologic Diseases, Beijing, China
| | - Jinghua Shi
- Department of Obstetrics and Gynecology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
- National Clinical Research Center for Obstetric & Gynecologic Diseases, Beijing, China
| | - Yi Dai
- Department of Obstetrics and Gynecology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
- National Clinical Research Center for Obstetric & Gynecologic Diseases, Beijing, China
| | - Xiaoyan Li
- Department of Obstetrics and Gynecology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
- National Clinical Research Center for Obstetric & Gynecologic Diseases, Beijing, China
| | - Jinhua Leng
- Department of Obstetrics and Gynecology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
- National Clinical Research Center for Obstetric & Gynecologic Diseases, Beijing, China
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9
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Shrouder JJ, Calandra GM, Filser S, Varga DP, Besson-Girard S, Mamrak U, Dorok M, Bulut-Impraim B, Seker FB, Gesierich B, Laredo F, Wehn AC, Khalin I, Bayer P, Liesz A, Gokce O, Plesnila N. Continued dysfunction of capillary pericytes promotes no-reflow after experimental stroke in vivo. Brain 2024; 147:1057-1074. [PMID: 38153327 DOI: 10.1093/brain/awad401] [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: 03/17/2023] [Revised: 11/15/2023] [Accepted: 11/16/2023] [Indexed: 12/29/2023] Open
Abstract
Incomplete reperfusion of the microvasculature ('no-reflow') after ischaemic stroke damages salvageable brain tissue. Previous ex vivo studies suggest pericytes are vulnerable to ischaemia and may exacerbate no-reflow, but the viability of pericytes and their association with no-reflow remains under-explored in vivo. Using longitudinal in vivo two-photon single-cell imaging over 7 days, we showed that 87% of pericytes constrict during cerebral ischaemia and remain constricted post reperfusion, and 50% of the pericyte population are acutely damaged. Moreover, we revealed ischaemic pericytes to be fundamentally implicated in capillary no-reflow by limiting and arresting blood flow within the first 24 h post stroke. Despite sustaining acute membrane damage, we observed that over half of all cortical pericytes survived ischaemia and responded to vasoactive stimuli, upregulated unique transcriptomic profiles and replicated. Finally, we demonstrated the delayed recovery of capillary diameter by ischaemic pericytes after reperfusion predicted vessel reconstriction in the subacute phase of stroke. Cumulatively, these findings demonstrate that surviving cortical pericytes remain both viable and promising therapeutic targets to counteract no-reflow after ischaemic stroke.
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Affiliation(s)
- Joshua James Shrouder
- Institute for Stroke and Dementia Research (ISD), LMU University Hospital, Ludwig-Maximilians-University (LMU) Munich, 81377 Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), 81377 Munich, Germany
| | - Gian Marco Calandra
- Institute for Stroke and Dementia Research (ISD), LMU University Hospital, Ludwig-Maximilians-University (LMU) Munich, 81377 Munich, Germany
| | - Severin Filser
- Institute for Stroke and Dementia Research (ISD), LMU University Hospital, Ludwig-Maximilians-University (LMU) Munich, 81377 Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), 81377 Munich, Germany
- Core Research Facilities and Services-Light Microscope Facility, German Center for Neurodegenerative Diseases (DZNE), 53127 Bonn, Germany
| | - Daniel Peter Varga
- Institute for Stroke and Dementia Research (ISD), LMU University Hospital, Ludwig-Maximilians-University (LMU) Munich, 81377 Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), 81377 Munich, Germany
| | - Simon Besson-Girard
- Institute for Stroke and Dementia Research (ISD), LMU University Hospital, Ludwig-Maximilians-University (LMU) Munich, 81377 Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), 81377 Munich, Germany
| | - Uta Mamrak
- Institute for Stroke and Dementia Research (ISD), LMU University Hospital, Ludwig-Maximilians-University (LMU) Munich, 81377 Munich, Germany
| | - Maximilian Dorok
- Institute for Stroke and Dementia Research (ISD), LMU University Hospital, Ludwig-Maximilians-University (LMU) Munich, 81377 Munich, Germany
| | - Buket Bulut-Impraim
- Institute for Stroke and Dementia Research (ISD), LMU University Hospital, Ludwig-Maximilians-University (LMU) Munich, 81377 Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), 81377 Munich, Germany
| | - Fatma Burcu Seker
- Institute for Stroke and Dementia Research (ISD), LMU University Hospital, Ludwig-Maximilians-University (LMU) Munich, 81377 Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), 81377 Munich, Germany
| | - Benno Gesierich
- Institute for Stroke and Dementia Research (ISD), LMU University Hospital, Ludwig-Maximilians-University (LMU) Munich, 81377 Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), 81377 Munich, Germany
| | - Fabio Laredo
- Institute for Stroke and Dementia Research (ISD), LMU University Hospital, Ludwig-Maximilians-University (LMU) Munich, 81377 Munich, Germany
| | - Antonia Clarissa Wehn
- Institute for Stroke and Dementia Research (ISD), LMU University Hospital, Ludwig-Maximilians-University (LMU) Munich, 81377 Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), 81377 Munich, Germany
- Department of Neurosurgery, LMU University Hospital, Ludwig-Maximilians-University (LMU) Munich, 81377 Munich, Germany
| | - Igor Khalin
- Institute for Stroke and Dementia Research (ISD), LMU University Hospital, Ludwig-Maximilians-University (LMU) Munich, 81377 Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), 81377 Munich, Germany
- Normandie University, UNICAEN, INSERM UMR-S U1237, Physiopathology and Imaging of Neurological Disorders (PhIND), GIP Cyceron, Institute Blood and Brain @ Caen-Normandie (BB@C), 14000 Caen, France
| | - Patrick Bayer
- Institute for Stroke and Dementia Research (ISD), LMU University Hospital, Ludwig-Maximilians-University (LMU) Munich, 81377 Munich, Germany
| | - Arthur Liesz
- Institute for Stroke and Dementia Research (ISD), LMU University Hospital, Ludwig-Maximilians-University (LMU) Munich, 81377 Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), 81377 Munich, Germany
| | - Ozgun Gokce
- Institute for Stroke and Dementia Research (ISD), LMU University Hospital, Ludwig-Maximilians-University (LMU) Munich, 81377 Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), 81377 Munich, Germany
| | - Nikolaus Plesnila
- Institute for Stroke and Dementia Research (ISD), LMU University Hospital, Ludwig-Maximilians-University (LMU) Munich, 81377 Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), 81377 Munich, Germany
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10
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Mester JR, Rozak MW, Dorr A, Goubran M, Sled JG, Stefanovic B. Network response of brain microvasculature to neuronal stimulation. Neuroimage 2024; 287:120512. [PMID: 38199427 DOI: 10.1016/j.neuroimage.2024.120512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 12/21/2023] [Accepted: 01/04/2024] [Indexed: 01/12/2024] Open
Abstract
Neurovascular coupling (NVC), or the adjustment of blood flow in response to local increases in neuronal activity is a hallmark of healthy brain function, and the physiological foundation for functional magnetic resonance imaging (fMRI). However, it remains only partly understood due to the high complexity of the structure and function of the cerebrovascular network. Here we set out to understand NVC at the network level, i.e. map cerebrovascular network reactivity to activation of neighbouring neurons within a 500×500×500 μm3 cortical volume (∼30 high-resolution 3-nL fMRI voxels). Using 3D two-photon fluorescence microscopy data, we quantified blood volume and flow changes in the brain vessels in response to spatially targeted optogenetic activation of cortical pyramidal neurons. We registered the vessels in a series of image stacks acquired before and after stimulations and applied a deep learning pipeline to segment the microvascular network from each time frame acquired. We then performed image analysis to extract the microvascular graphs, and graph analysis to identify the branch order of each vessel in the network, enabling the stratification of vessels by their branch order, designating branches 1-3 as precapillary arterioles and branches 4+ as capillaries. Forty-five percent of all vessels showed significant calibre changes; with 85 % of responses being dilations. The largest absolute CBV change was in the capillaries; the smallest, in the venules. Capillary CBV change was also the largest fraction of the total CBV change, but normalized to the baseline volume, arterioles and precapillary arterioles showed the biggest relative CBV change. From linescans along arteriole-venule microvascular paths, we measured red blood cell velocities and hematocrit, allowing for estimation of pressure and local resistance along these paths. While diameter changes following neuronal activation gradually declined along the paths; the pressure drops from arterioles to venules increased despite decreasing resistance: blood flow thus increased more than local resistance decreases would predict. By leveraging functional volumetric imaging and high throughput deep learning-based analysis, our study revealed distinct hemodynamic responses across the vessel types comprising the microvascular network. Our findings underscore the need for large, dense sampling of brain vessels for characterization of neurovascular coupling at the network level in health and disease.
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Affiliation(s)
- James R Mester
- University of Toronto, Department of Medical Biophysics, Toronto, Ontario, Canada; Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Matthew W Rozak
- University of Toronto, Department of Medical Biophysics, Toronto, Ontario, Canada; Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Adrienne Dorr
- Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Maged Goubran
- University of Toronto, Department of Medical Biophysics, Toronto, Ontario, Canada; Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - John G Sled
- University of Toronto, Department of Medical Biophysics, Toronto, Ontario, Canada; Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Bojana Stefanovic
- University of Toronto, Department of Medical Biophysics, Toronto, Ontario, Canada; Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada.
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11
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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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12
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Gastfriend BD, Snyder ME, Holt HE, Daneman R, Palecek SP, Shusta EV. Notch3 directs differentiation of brain mural cells from human pluripotent stem cell-derived neural crest. SCIENCE ADVANCES 2024; 10:eadi1737. [PMID: 38306433 PMCID: PMC10836734 DOI: 10.1126/sciadv.adi1737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 01/04/2024] [Indexed: 02/04/2024]
Abstract
Brain mural cells regulate development and function of the blood-brain barrier and control blood flow. Existing in vitro models of human brain mural cells have low expression of key mural cell genes, including NOTCH3. Thus, we asked whether activation of Notch3 signaling in hPSC-derived neural crest could direct the differentiation of brain mural cells with an improved transcriptional profile. Overexpression of the Notch3 intracellular domain (N3ICD) induced expression of mural cell markers PDGFRβ, TBX2, FOXS1, KCNJ8, SLC6A12, and endogenous Notch3. The resulting N3ICD-derived brain mural cells produced extracellular matrix, self-assembled with endothelial cells, and had functional KATP channels. ChIP-seq revealed that Notch3 serves as a direct input to relatively few genes in the context of this differentiation process. Our work demonstrates that activation of Notch3 signaling is sufficient to direct the differentiation of neural crest to mural cells and establishes a developmentally relevant differentiation protocol.
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Affiliation(s)
- Benjamin D Gastfriend
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Margaret E Snyder
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Hope E Holt
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Richard Daneman
- Departments of Neurosciences and Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Sean P Palecek
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Eric V Shusta
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
- Department of Neurological Surgery, University of Wisconsin-Madison, Madison, WI 53706, USA
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13
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McDonald H, Gardner-Russell J, Alarcon-Martinez L. Orchestrating Blood Flow in the Retina: Interpericyte Tunnelling Nanotube Communication. Results Probl Cell Differ 2024; 73:229-247. [PMID: 39242382 DOI: 10.1007/978-3-031-62036-2_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/09/2024]
Abstract
The retina transforms light into electrical signals, which are sent to the brain via the optic nerve to form our visual perception. This complex signal processing is performed by the retinal neuron and requires a significant amount of energy. Since neurons are unable to store energy, they must obtain glucose and oxygen from the bloodstream to produce energy to match metabolic needs. This process is called neurovascular coupling (NVC), and it is based on a precise mechanism that is not totally understood. The discovery of fine tubular processes termed tunnelling nanotubes (TNTs) set a new type of cell-to-cell communication. TNTs are extensions of the cellular membrane that allow the transfer of material between connected cells. Recently, they have been reported in the brain and retina of living mice, where they connect pericytes, which are vascular mural cells that regulate vessel diameter. Accordingly, these TNTs were termed interpericyte tunnelling nanotubes (IPTNTs), which showed a vital role in blood delivery and NVC. In this chapter, we review the involvement of TNTs in NVC and discuss their implications in retinal neurodegeneration.
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Affiliation(s)
- Hannah McDonald
- Centre for Eye Research Australia, Melbourne, VIC, Australia
- Department of Ophthalmology, University of Melbourne, Melbourne, VIC, Australia
- The Royal Victorian Eye and Ear Hospital, Melbourne, VIC, Australia
| | - Jesse Gardner-Russell
- Centre for Eye Research Australia, Melbourne, VIC, Australia
- Department of Ophthalmology, University of Melbourne, Melbourne, VIC, Australia
- The Royal Victorian Eye and Ear Hospital, Melbourne, VIC, Australia
| | - Luis Alarcon-Martinez
- Centre for Eye Research Australia, Melbourne, VIC, Australia.
- Department of Ophthalmology, University of Melbourne, Melbourne, VIC, Australia.
- The Royal Victorian Eye and Ear Hospital, Melbourne, VIC, Australia.
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14
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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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15
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Evdochim L, Chiriac E, Avram M, Dobrescu L, Dobrescu D, Stanciu S, Halichidis S. Red Blood Cells' Area Deformation as the Origin of the Photoplethysmography Signal. SENSORS (BASEL, SWITZERLAND) 2023; 23:9515. [PMID: 38067889 PMCID: PMC10708758 DOI: 10.3390/s23239515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 11/22/2023] [Accepted: 11/28/2023] [Indexed: 12/18/2023]
Abstract
The origin of the photoplethysmography (PPG) signal is a debatable topic, despite plausible models being addressed. One concern revolves around the correlation between the mechanical waveform's pulsatile nature and the associated biomechanism. The interface between these domains requires a clear mathematical or physical model that can explain physiological behavior. Describing the correct origin of the recorded optical waveform not only benefits the development of the next generation of biosensors but also defines novel health markers. In this study, the assumption of a pulsatile nature is based on the mechanism of blood microcirculation. At this level, two interconnected phenomena occur: variation in blood flow velocity through the capillary network and red blood cell (RBC) shape deformation. The latter effect was qualitatively investigated in synthetic capillaries to assess the experimental data needed for PPG model development. Erythrocytes passed through 10 µm and 6 µm microchannel widths with imposed velocities between 50 µm/s and 2000 µm/s, according to real scenarios. As a result, the length and area deformation of RBCs followed a logarithmic law function of the achieved traveling speeds. Applying radiometric expertise on top, mechanical-optical insights are obtained regarding PPG's pulsatile nature. The mathematical equations derived from experimental data correlate microcirculation physiologic with waveform behavior at a high confidence level. The transfer function between the biomechanics and the optical signal is primarily influenced by the vasomotor state, capillary network orientation, concentration, and deformation performance of erythrocytes.
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Affiliation(s)
- Lucian Evdochim
- Department of Electronic Devices, Circuits, and Architectures, Faculty of Electronics, Telecommunications and Information Technology, University Politehnica of Bucharest, 060042 Bucharest, Romania; (L.D.); (D.D.)
| | - Eugen Chiriac
- National Institute for Research and Development in Microtechnologies—IMT Bucharest, 077190 Voluntari, Romania; (E.C.); (M.A.)
| | - Marioara Avram
- National Institute for Research and Development in Microtechnologies—IMT Bucharest, 077190 Voluntari, Romania; (E.C.); (M.A.)
| | - Lidia Dobrescu
- Department of Electronic Devices, Circuits, and Architectures, Faculty of Electronics, Telecommunications and Information Technology, University Politehnica of Bucharest, 060042 Bucharest, Romania; (L.D.); (D.D.)
| | - Dragoș Dobrescu
- Department of Electronic Devices, Circuits, and Architectures, Faculty of Electronics, Telecommunications and Information Technology, University Politehnica of Bucharest, 060042 Bucharest, Romania; (L.D.); (D.D.)
| | - Silviu Stanciu
- Laboratory of Cardiovascular Noninvasive Investigations, Dr. Carol Davila Central Military Emergency University Hospital, 010242 Bucharest, Romania;
| | - Stela Halichidis
- Department of Clinical Medical Disciplines, Faculty of Medicine, Ovidius University of Constanta, 900527 Constanta, Romania;
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16
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Bonney SK, Nielson CD, Sosa MJ, Shih AY. Capillary regression leads to sustained local hypoperfusion by inducing constriction of upstream transitional vessels. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.28.564529. [PMID: 37961686 PMCID: PMC10635020 DOI: 10.1101/2023.10.28.564529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
In the brain, a microvascular sensory web coordinates oxygen delivery to regions of neuronal activity. This involves a dense network of capillaries that send conductive signals upstream to feeding arterioles to promote vasodilation and blood flow. Although this process is critical to the metabolic supply of healthy brain tissue, it may also be a point of vulnerability in disease. Deterioration of capillary networks is a hallmark of many neurological disorders and how this web is engaged during vascular damage remains unknown. We performed in vivo two-photon microscopy on young adult mural cell reporter mice and induced focal capillary injuries using precise two-photon laser irradiation of single capillaries. We found that ∼63% of the injuries resulted in regression of the capillary segment 7-14 days following injury, and the remaining repaired to re-establish blood flow within 7 days. Injuries that resulted in capillary regression induced sustained vasoconstriction in the upstream arteriole-capillary transition (ACT) zone at least 21 days post-injury in both awake and anesthetized mice. This abnormal vasoconstriction involved attenuation of vasomotor dynamics and uncoupling from mural cell calcium signaling following capillary regression. Consequently, blood flow was reduced in the ACT zone and in secondary, uninjured downstream capillaries. These findings demonstrate how capillary injury and regression, as often seen in age-related neurological disease, can impair the microvascular sensory web and contribute to cerebral hypoperfusion. SIGNIFICANCE Deterioration of the capillary network is a characteristic of many neurological diseases and can exacerbate neuronal dysfunction and degeneration due to poor blood perfusion. Here we show that focal capillary injuries can induce vessel regression and elicit sustained vasoconstriction in upstream transitional vessels that branch from cortical penetrating arterioles. This reduces blood flow to broader, uninjured regions of the same microvascular network. These findings suggest that widespread and cumulative damage to brain capillaries in neurological disease may broadly affect blood supply and contribute to hypoperfusion through their remote actions.
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17
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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: 9] [Impact Index Per Article: 9.0] [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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18
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Wu X, Li JR, Fu Y, Chen DY, Nie H, Tang ZP. From static to dynamic: live observation of the support system after ischemic stroke by two photon-excited fluorescence laser-scanning microscopy. Neural Regen Res 2023; 18:2093-2107. [PMID: 37056116 PMCID: PMC10328295 DOI: 10.4103/1673-5374.369099] [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: 10/14/2022] [Revised: 12/21/2022] [Accepted: 01/13/2023] [Indexed: 02/17/2023] Open
Abstract
Ischemic stroke is one of the most common causes of mortality and disability worldwide. However, treatment efficacy and the progress of research remain unsatisfactory. As the critical support system and essential components in neurovascular units, glial cells and blood vessels (including the blood-brain barrier) together maintain an optimal microenvironment for neuronal function. They provide nutrients, regulate neuronal excitability, and prevent harmful substances from entering brain tissue. The highly dynamic networks of this support system play an essential role in ischemic stroke through processes including brain homeostasis, supporting neuronal function, and reacting to injuries. However, most studies have focused on postmortem animals, which inevitably lack critical information about the dynamic changes that occur after ischemic stroke. Therefore, a high-precision technique for research in living animals is urgently needed. Two-photon fluorescence laser-scanning microscopy is a powerful imaging technique that can facilitate live imaging at high spatiotemporal resolutions. Two-photon fluorescence laser-scanning microscopy can provide images of the whole-cortex vascular 3D structure, information on multicellular component interactions, and provide images of structure and function in the cranial window. This technique shifts the existing research paradigm from static to dynamic, from flat to stereoscopic, and from single-cell function to multicellular intercommunication, thus providing direct and reliable evidence to identify the pathophysiological mechanisms following ischemic stroke in an intact brain. In this review, we discuss exciting findings from research on the support system after ischemic stroke using two-photon fluorescence laser-scanning microscopy, highlighting the importance of dynamic observations of cellular behavior and interactions in the networks of the brain's support systems. We show the excellent application prospects and advantages of two-photon fluorescence laser-scanning microscopy and predict future research developments and directions in the study of ischemic stroke.
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Affiliation(s)
- Xuan Wu
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Jia-Rui Li
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Yu Fu
- Department of Geriatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Dan-Yang Chen
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Hao Nie
- Department of Geriatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Zhou-Ping Tang
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
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19
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Abstract
The vasculature consists of vessels of different sizes that are arranged in a hierarchical pattern. Two cell populations work in concert to establish this pattern during embryonic development and adopt it to changes in blood flow demand later in life: endothelial cells that line the inner surface of blood vessels, and adjacent vascular mural cells, including smooth muscle cells and pericytes. Despite recent progress in elucidating the signalling pathways controlling their crosstalk, much debate remains with regard to how mural cells influence endothelial cell biology and thereby contribute to the regulation of blood vessel formation and diameters. In this Review, I discuss mural cell functions and their interactions with endothelial cells, focusing on how these interactions ensure optimal blood flow patterns. Subsequently, I introduce the signalling pathways controlling mural cell development followed by an overview of mural cell ontogeny with an emphasis on the distinguishing features of mural cells located on different types of blood vessels. Ultimately, I explore therapeutic strategies involving mural cells to alleviate tissue ischemia and improve vascular efficiency in a variety of diseases.
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Affiliation(s)
- Arndt F. Siekmann
- Department of Cell and Developmental Biology, Perelman School of Medicine at the University of Pennsylvania, 1114 Biomedical Research Building, 421 Curie Boulevard, Philadelphia, PA 19104, USA
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20
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Zhao F, Tomita M, Dutta A. Operational Modal Analysis of Near-Infrared Spectroscopy Measure of 2-Month Exercise Intervention Effects in Sedentary Older Adults with Diabetes and Cognitive Impairment. Brain Sci 2023; 13:1099. [PMID: 37509027 PMCID: PMC10377417 DOI: 10.3390/brainsci13071099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 07/11/2023] [Accepted: 07/17/2023] [Indexed: 07/30/2023] Open
Abstract
The Global Burden of Disease Study (GBD 2019 Diseases and Injuries Collaborators) found that diabetes significantly increases the overall burden of disease, leading to a 24.4% increase in disability-adjusted life years. Persistently high glucose levels in diabetes can cause structural and functional changes in proteins throughout the body, and the accumulation of protein aggregates in the brain that can be associated with the progression of Alzheimer's Disease (AD). To address this burden in type 2 diabetes mellitus (T2DM), a combined aerobic and resistance exercise program was developed based on the recommendations of the American College of Sports Medicine. The prospectively registered clinical trials (NCT04626453, NCT04812288) involved two groups: an Intervention group of older sedentary adults with T2DM and a Control group of healthy older adults who could be either active or sedentary. The completion rate for the 2-month exercise program was high, with participants completing on an average of 89.14% of the exercise sessions. This indicated that the program was practical, feasible, and well tolerated, even during the COVID-19 pandemic. It was also safe, requiring minimal equipment and no supervision. Our paper presents portable near-infrared spectroscopy (NIRS) based measures that showed muscle oxygen saturation (SmO2), i.e., the balance between oxygen delivery and oxygen consumption in muscle, drop during bilateral heel rise task (BHR) and the 6 min walk task (6MWT) significantly (p < 0.05) changed at the post-intervention follow-up from the pre-intervention baseline in the T2DM Intervention group participants. Moreover, post-intervention changes from pre-intervention baseline for the prefrontal activation (both oxyhemoglobin and deoxyhemoglobin) showed statistically significant (p < 0.05, q < 0.05) effect at the right superior frontal gyrus, dorsolateral, during the Mini-Cog task. Here, operational modal analysis provided further insights into the 2-month exercise intervention effects on the very-low-frequency oscillations (<0.05 Hz) during the Mini-Cog task that improved post-intervention in the sedentary T2DM Intervention group from their pre-intervention baseline when compared to active healthy Control group. Then, the 6MWT distance significantly (p < 0.01) improved in the T2DM Intervention group at post-intervention follow-up from pre-intervention baseline that showed improved aerobic capacity and endurance. Our portable NIRS based measures have practical implications at the point of care for the therapists as they can monitor muscle and brain oxygenation changes during physical and cognitive tests to prescribe personalized physical exercise doses without triggering individual stress response, thereby, enhancing vascular health in T2DM.
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Affiliation(s)
- Fei Zhao
- Department of Rehabilitation Science, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY 14214, USA
| | - Machiko Tomita
- Department of Rehabilitation Science, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY 14214, USA
| | - Anirban Dutta
- School of Engineering, University of Lincoln, Lincoln LN67TS, UK
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21
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Inoue Y, Shue F, Bu G, Kanekiyo T. Pathophysiology and probable etiology of cerebral small vessel disease in vascular dementia and Alzheimer's disease. Mol Neurodegener 2023; 18:46. [PMID: 37434208 PMCID: PMC10334598 DOI: 10.1186/s13024-023-00640-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 06/28/2023] [Indexed: 07/13/2023] Open
Abstract
Vascular cognitive impairment and dementia (VCID) is commonly caused by vascular injuries in cerebral large and small vessels and is a key driver of age-related cognitive decline. Severe VCID includes post-stroke dementia, subcortical ischemic vascular dementia, multi-infarct dementia, and mixed dementia. While VCID is acknowledged as the second most common form of dementia after Alzheimer's disease (AD) accounting for 20% of dementia cases, VCID and AD frequently coexist. In VCID, cerebral small vessel disease (cSVD) often affects arterioles, capillaries, and venules, where arteriolosclerosis and cerebral amyloid angiopathy (CAA) are major pathologies. White matter hyperintensities, recent small subcortical infarcts, lacunes of presumed vascular origin, enlarged perivascular space, microbleeds, and brain atrophy are neuroimaging hallmarks of cSVD. The current primary approach to cSVD treatment is to control vascular risk factors such as hypertension, dyslipidemia, diabetes, and smoking. However, causal therapeutic strategies have not been established partly due to the heterogeneous pathogenesis of cSVD. In this review, we summarize the pathophysiology of cSVD and discuss the probable etiological pathways by focusing on hypoperfusion/hypoxia, blood-brain barriers (BBB) dysregulation, brain fluid drainage disturbances, and vascular inflammation to define potential diagnostic and therapeutic targets for cSVD.
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Affiliation(s)
- Yasuteru Inoue
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224 USA
| | - Francis Shue
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224 USA
| | - Guojun Bu
- SciNeuro Pharmaceuticals, Rockville, MD 20850 USA
| | - Takahisa Kanekiyo
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224 USA
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22
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Sakaguchi M, Nakajima R, Ichinose T, Tanaka S, Kimura R, Sabit H, Nakada S, Nakada M. α-SMA positive vascular mural cells suppress cyst formation in hemangioblastoma. Brain Tumor Pathol 2023:10.1007/s10014-023-00465-6. [PMID: 37273000 DOI: 10.1007/s10014-023-00465-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 05/23/2023] [Indexed: 06/06/2023]
Abstract
Approximately 60% of hemangioblastomas (HBs) have peritumoral cysts adjacent to the tumor, which can cause neurological deficits due to the mass effect, and the management of cyst formation is a clinical challenge. Vascular mural cells surrounding endothelial cells consist of vascular smooth muscle cells (vSMCs) and pericytes, which are essential elements that support blood vessels and regulate permeability. This study investigated the involvement of mural cells in cyst formation. We analyzed the expression of α-smooth muscle actin (α-SMA), platelet-derived growth factor receptor-beta (PDGFRB), and CD31 in 39 consecutive human cerebellar HBs, 20 of cystic and 19 of solid type. Solid type HBs showed stronger diffuse expression of α-SMA in precapillary arterioles and capillaries within the tumor than cystic type HBs (p = 0.001), whereas there was no difference in PDGFRB and CD31 expression. Detailed observation with immunofluorescence demonstrated that α-SMA was expressed in vascular mural cells surrounding capillaries in the solid rather than in the cystic type. Multivariate analysis including various clinical and pathological factors showed that lower α-SMA expression was significantly correlated with cyst formation (p < 0.001). Our data suggested that vascular mural cells from precapillary arterioles to capillaries expressing α-SMA may be pericytes and play a crucial role in HB cystogenesis.
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Affiliation(s)
- Maki Sakaguchi
- Department of Neurosurgery, Graduate School of Medical Science, Kanazawa University, 13-1 Takara-Machi, Kanazawa, 920-8641, Japan
- Department of Diagnostic Pathology, Kanazawa University Hospital, Kanazawa, Japan
| | - Riho Nakajima
- Department of Occupational Therapy, Faculty of Health Science, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Toshiya Ichinose
- Department of Neurosurgery, Graduate School of Medical Science, Kanazawa University, 13-1 Takara-Machi, Kanazawa, 920-8641, Japan
| | - Shingo Tanaka
- Department of Neurosurgery, Graduate School of Medical Science, Kanazawa University, 13-1 Takara-Machi, Kanazawa, 920-8641, Japan
| | - Ryouken Kimura
- Department of Neurosurgery, Graduate School of Medical Science, Kanazawa University, 13-1 Takara-Machi, Kanazawa, 920-8641, Japan
| | - Hemragul Sabit
- Department of Neurosurgery, Graduate School of Medical Science, Kanazawa University, 13-1 Takara-Machi, Kanazawa, 920-8641, Japan
| | - Satoko Nakada
- Department of Diagnostic Pathology, Kanazawa University Hospital, Kanazawa, Japan
- Department of Pathology and Laboratory Medicine, Hokuriku Brain and Neuromuscular Disease Center, National Hospital Organization Iou National Hospital, Kanazawa, Japan
| | - Mitsutoshi Nakada
- Department of Neurosurgery, Graduate School of Medical Science, Kanazawa University, 13-1 Takara-Machi, Kanazawa, 920-8641, Japan.
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23
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Suzuki H, Takeda H, Takuwa H, Ji B, Higuchi M, Kanno I, Masamoto K. Capillary responses to functional and pathological activations rely on the capillary states at rest. J Cereb Blood Flow Metab 2023; 43:1010-1024. [PMID: 36752020 PMCID: PMC10196750 DOI: 10.1177/0271678x231156372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 01/09/2023] [Accepted: 01/19/2023] [Indexed: 02/09/2023]
Abstract
Brain capillaries play a crucial role in maintaining cellular viability and thus preventing neurodegeneration. The aim of this study was to characterize the brain capillary morphology at rest and during neural activation based on a big data analysis from three-dimensional microangiography. Neurovascular responses were measured using a genetic calcium sensor expressed in neurons and microangiography with two-photon microscopy, while neural acivity was modulated by stimulation of contralateral whiskers or by a seizure evoked by kainic acid. For whisker stimulation, 84% of the capillary sites showed no detectable diameter change. The remaining 10% and 6% were dilated and constricted, respectively. Significant differences were observed for capillaries in the diameter at rest between the locations of dilation and constriction. Even the seizures resulted in 44% of the capillaries having no detectable change in diameter, while 56% of the capillaries dilated. The extent of dilation was dependent on the diameter at rest. In conclusion, big data analysis on brain capillary morphology has identified at least two types of capillary states: capillaries with diameters that are relatively large at rest and stable over time regardless of neural activity and capillaries whose diameters are relatively small at rest and vary according to neural activity.
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Affiliation(s)
- Hiroki Suzuki
- Graduate School of
Informatics and Engineering, University of Electro-Communications,
Tokyo, Japan
| | - Hiroshi Takeda
- Graduate School of
Informatics and Engineering, University of Electro-Communications,
Tokyo, Japan
| | - Hiroyuki Takuwa
- Department of Functional
Brain Imaging, National Institutes for Quantum Science and Technology,
Chiba, Japan
| | - Bin Ji
- Department of Functional
Brain Imaging, National Institutes for Quantum Science and Technology,
Chiba, Japan
- Department of Radiopharmacy
and Molecular Imaging, School of Pharmacy, Fudan University, Shanghai,
China
| | - Makoto Higuchi
- Department of Functional
Brain Imaging, National Institutes for Quantum Science and Technology,
Chiba, Japan
| | - Iwao Kanno
- Department of Functional
Brain Imaging, National Institutes for Quantum Science and Technology,
Chiba, Japan
| | - Kazuto Masamoto
- Graduate School of
Informatics and Engineering, University of Electro-Communications,
Tokyo, Japan
- Department of Functional
Brain Imaging, National Institutes for Quantum Science and Technology,
Chiba, Japan
- Center for Neuroscience and
Biomedical Engineering, University of Electro-Communications, Tokyo,
Japan
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24
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Zhukov O, He C, Soylu-Kucharz R, Cai C, Lauritzen AD, Aldana BI, Björkqvist M, Lauritzen M, Kucharz K. Preserved blood-brain barrier and neurovascular coupling in female 5xFAD model of Alzheimer's disease. Front Aging Neurosci 2023; 15:1089005. [PMID: 37261266 PMCID: PMC10228387 DOI: 10.3389/fnagi.2023.1089005] [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: 11/03/2022] [Accepted: 04/17/2023] [Indexed: 06/02/2023] Open
Abstract
Introduction Dysfunction of the cerebral vasculature is considered one of the key components of Alzheimer's disease (AD), but the mechanisms affecting individual brain vessels are poorly understood. Methods Here, using in vivo two-photon microscopy in superficial cortical layers and ex vivo imaging across brain regions, we characterized blood-brain barrier (BBB) function and neurovascular coupling (NVC) at the level of individual brain vessels in adult female 5xFAD mice, an aggressive amyloid-β (Aβ) model of AD. Results We report a lack of abnormal increase in adsorptive-mediated transcytosis of albumin and preserved paracellular barrier for fibrinogen and small molecules despite an extensive load of Aβ. Likewise, the NVC responses to somatosensory stimulation were preserved at all regulatory segments of the microvasculature: penetrating arterioles, precapillary sphincters, and capillaries. Lastly, the Aβ plaques did not affect the density of capillary pericytes. Conclusion Our findings provide direct evidence of preserved microvascular function in the 5xFAD mice and highlight the critical dependence of the experimental outcomes on the choice of preclinical models of AD. We propose that the presence of parenchymal Aβ does not warrant BBB and NVC dysfunction and that the generalized view that microvascular impairment is inherent to Aβ aggregation may need to be revised.
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Affiliation(s)
- Oleg Zhukov
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Chen He
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Rana Soylu-Kucharz
- Biomarkers in Brain Disease, Department of Experimental Medical Sciences, Lund University, Lund, Sweden
| | - Changsi Cai
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Blanca Irene Aldana
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Maria Björkqvist
- Biomarkers in Brain Disease, Department of Experimental Medical Sciences, Lund University, Lund, Sweden
| | - Martin Lauritzen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Clinical Neurophysiology, Rigshospitalet, Copenhagen, Denmark
| | - Krzysztof Kucharz
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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25
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Lia A, Di Spiezio A, Speggiorin M, Zonta M. Two decades of astrocytes in neurovascular coupling. FRONTIERS IN NETWORK PHYSIOLOGY 2023; 3:1162757. [PMID: 37078069 PMCID: PMC10106690 DOI: 10.3389/fnetp.2023.1162757] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 03/23/2023] [Indexed: 04/05/2023]
Abstract
The brain is a highly energy demanding organ, which accounts in humans for the 20% of total energy consumption at resting state although comprising only 2% of the body mass. The necessary delivery of nutrients to brain parenchyma is ensured by the cerebral circulatory system, through the exchange of glucose and oxygen (O2) at the capillary level. Notably, a tight spatial and temporal correlation exists between local increases in neuronal activity and the subsequent changes in regional cerebral blood flow. The recognized concept of neurovascular coupling (NVC), also named functional hyperemia, expresses this close relationship and stands at the basis of the modern functional brain imaging techniques. Different cellular and molecular mechanisms have been proposed to mediate this tight coupling. In this context, astrocytes are ideally positioned to act as relay elements that sense neuronal activity through their perisynaptic processes and release vasodilator agents at their endfeet in contact with brain parenchymal vessels. Two decades after the astrocyte involvement in neurovascular coupling has been proposed, we here review the experimental evidence that contributed to unraveling the molecular and cellular mechanisms underlying cerebral blood flow regulation. While traveling through the different controversies that moved the research in this field, we keep a peculiar focus on those exploring the role of astrocytes in neurovascular coupling and conclude with two sections related to methodological aspects in neurovascular research and to some pathological conditions resulting in altered neurovascular coupling.
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Affiliation(s)
- Annamaria Lia
- Neuroscience Institute, National Research Council (CNR), Padua, Italy
| | - Alessandro Di Spiezio
- Neuroscience Institute, National Research Council (CNR), Padua, Italy
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | | | - Micaela Zonta
- Neuroscience Institute, National Research Council (CNR), Padua, Italy
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26
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Madsen LS, Parbo P, Ismail R, Gottrup H, Østergaard L, Brooks DJ, Eskildsen SF. Capillary dysfunction correlates with cortical amyloid load in early Alzheimer's disease. Neurobiol Aging 2023; 123:1-9. [PMID: 36610198 DOI: 10.1016/j.neurobiolaging.2022.12.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 12/09/2022] [Accepted: 12/12/2022] [Indexed: 12/23/2022]
Abstract
Alterations in cerebral perfusion is increasingly considered to play a crucial role in Alzheimer's disease (AD) and together with accumulated amyloid-β, deficiencies in the brain microvascular circulation may result in local hypoxia. Here, we studied alterations in cerebral circulation and the correlation between amyloid-β load and cerebral perfusion in prodromal AD (pAD). Using dynamic susceptibility contrast MRI and PET, we evaluated cerebral perfusion and amyloid-β levels in 19 individuals with mild cognitive impairment (MCI) and high amyloid-β load (pAD-MCI), 13 MCI individuals without AD pathology and 21 healthy controls. The pAD-MCI group showed significantly lower microvascular blood flow and significantly higher heterogeneity of microvascular blood transit times (p < 0.01) compared with the other 2 groups. Additionally, in the pAD-MCI group raised amyloid-β levels correlated with decreased microvascular blood flow and increased heterogeneity of microvascular blood flow in frontal and temporal areas (p < 0.01). These results indicate a close connection between levels of amyloid-β deposition and brain microvascular perfusion in pAD. A vicious cycle may be established where amyloid-β load and deficiencies in brain perfusion may reinforce each other.
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Affiliation(s)
- Lasse S Madsen
- Department of Nuclear Medicine and PET-Centre, Aarhus University Hospital, Aarhus, Denmark; Center of Functionally Integrative Neuroscience, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.
| | - Peter Parbo
- Department of Nuclear Medicine, Odense University Hospital, Odense, Denmark
| | - Rola Ismail
- Department of Nuclear Medicine, Sygehus Lillebaelt, Kolding, Denmark
| | - Hanne Gottrup
- Dementia Clinic, Department of Neurology, Aarhus University Hospital, Aarhus, Denmark
| | - Leif Østergaard
- Center of Functionally Integrative Neuroscience, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; Department of Neuroradiology, Aarhus University Hospital, Aarhus, Denmark
| | - David J Brooks
- Department of Nuclear Medicine and PET-Centre, Aarhus University Hospital, Aarhus, Denmark; Institute of Translational and Clinical Research, University of Newcastle upon Tyne, Newcastle, UK
| | - Simon F Eskildsen
- Center of Functionally Integrative Neuroscience, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
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27
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Mughal A, Nelson MT, Hill-Eubanks D. The post-arteriole transitional zone: a specialized capillary region that regulates blood flow within the CNS microvasculature. J Physiol 2023; 601:889-901. [PMID: 36751860 PMCID: PMC9992301 DOI: 10.1113/jp282246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 01/13/2023] [Indexed: 02/09/2023] Open
Abstract
The brain is an energy hog, consuming available energy supplies at a rate out of all proportion to its relatively small size. This outsized demand, largely reflecting the unique computational activity of the brain, is met by an ensemble of neurovascular coupling mechanisms that link neuronal activity with local increases in blood delivery. This just-in-time replenishment strategy, made necessary by the limited energy-storage capacity of neurons, complicates the nutrient-delivery task of the cerebral vasculature, layering on a temporo-spatial requirement that invites - and challenges - mechanistic interpretation. The centre of gravity of research efforts to disentangle these mechanisms has shifted from an initial emphasis on astrocyte-arteriole-level processes to mechanisms that operate on the capillary level, a shift that has brought into sharp focus questions regarding the fine control of blood distribution to active neurons. As these investigations have drilled down into finer reaches of the microvasculature, they have revealed an arteriole-proximate subregion of CNS capillary networks that serves a regulatory function in directing blood flow into and within downstream capillaries. They have also illuminated differences in researchers' perspectives on the vascular structures and identity of mural cells in this region that impart the vasomodulatory effects that control blood distribution. In this review, we highlight the regulatory role of a variably named region of the microvasculature, referred to here as the post-arteriole transition zone, in channeling blood flow within CNS capillary networks, and underscore the contribution of dynamically contractile perivascular mural cell - generally, but not universally, recognized as pericytes - to this function.
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Affiliation(s)
- Amreen Mughal
- Department of Pharmacology, University of Vermont, Burlington, VT, USA
| | - Mark T. Nelson
- Department of Pharmacology, University of Vermont, Burlington, VT, USA
- Division of Cardiovascular Sciences, University of Manchester, Manchester, UK
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28
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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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29
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Cai C, Zambach SA, Grubb S, Tao L, He C, Lind BL, Thomsen KJ, Zhang X, Hald BO, Nielsen RM, Kim K, Devor A, Lønstrup M, Lauritzen MJ. Impaired dynamics of precapillary sphincters and pericytes at first-order capillaries predict reduced neurovascular function in the aging mouse brain. NATURE AGING 2023; 3:173-184. [PMID: 37118115 PMCID: PMC11081516 DOI: 10.1038/s43587-022-00354-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 12/20/2022] [Indexed: 04/30/2023]
Abstract
The microvascular inflow tract, comprising the penetrating arterioles, precapillary sphincters and first-order capillaries, is the bottleneck for brain blood flow and energy supply. Exactly how aging alters the structure and function of the microvascular inflow tract remains unclear. By in vivo four-dimensional two-photon imaging, we reveal an age-dependent decrease in vaso-responsivity accompanied by a decrease in vessel density close to the arterioles and loss of vascular mural cell processes, although the number of mural cell somas and their alpha smooth muscle actin density were preserved. The age-related reduction in vascular reactivity was mostly pronounced at precapillary sphincters, highlighting their crucial role in capillary blood flow regulation. Mathematical modeling revealed impaired pressure and flow control in aged mice during vasoconstriction. Interventions that preserve dynamics of cerebral blood vessels may ameliorate age-related decreases in blood flow and prevent brain frailty.
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Affiliation(s)
- Changsi Cai
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark.
| | - Stefan Andreas Zambach
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Søren Grubb
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Lechan Tao
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
- School of Biomedical Engineering, Shanghai Jiao-Tong University, Shanghai, China
| | - Chen He
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Barbara Lykke Lind
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Kirsten Joan Thomsen
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Xiao Zhang
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Bjørn Olav Hald
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Reena Murmu Nielsen
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Kayeon Kim
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Anna Devor
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Harvard Medical School, Massachusetts General Hospital, Charlestown, MA, USA
| | - Micael Lønstrup
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Martin Johannes Lauritzen
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark.
- Department of Clinical Neurophysiology, Rigshospitalet, Copenhagen, Denmark.
- Center for Healthy Aging, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark.
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30
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Markova V, Bogdanov L, Velikanova E, Kanonykina A, Frolov A, Shishkova D, Lazebnaya A, Kutikhin A. Endothelial Cell Markers Are Inferior to Vascular Smooth Muscle Cells Markers in Staining Vasa Vasorum and Are Non-Specific for Distinct Endothelial Cell Lineages in Clinical Samples. Int J Mol Sci 2023; 24:ijms24031959. [PMID: 36768296 PMCID: PMC9916324 DOI: 10.3390/ijms24031959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/15/2023] [Accepted: 01/18/2023] [Indexed: 01/20/2023] Open
Abstract
Current techniques for the detection of vasa vasorum (VV) in vascular pathology include staining for endothelial cell (EC) markers such as CD31 or VE-cadherin. However, this approach does not permit an objective assessment of vascular geometry upon vasospasm and the clinical relevance of endothelial specification markers found in developmental biology studies remains unclear. Here, we performed a combined immunostaining of rat abdominal aorta (rAA) and human saphenous vein (hSV) for various EC or vascular smooth muscle cell (VSMC) markers and found that the latter (e.g., alpha smooth muscle actin (α-SMA) or smooth muscle myosin heavy chain (SM-MHC)) ensure a several-fold higher signal-to-noise ratio irrespective of the primary antibody origin, fluorophore, or VV type (arterioles, venules, or capillaries). Further, α-SMA or SM-MHC staining allowed unbiased evaluation of the VV area under vasospasm. Screening of the molecular markers of endothelial heterogeneity (mechanosensitive transcription factors KLF2 and KLF4, arterial transcription factors HES1, HEY1, and ERG, venous transcription factor NR2F2, and venous/lymphatic markers PROX1, LYVE1, VEGFR3, and NRP2) have not revealed specific markers of any lineage in hSV (although KLF2 and PROX1 were restricted to venous endothelium in rAA), suggesting the need in high-throughput searches for the clinically relevant signatures of arterial, venous, lymphatic, or capillary differentiation.
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31
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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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32
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Stobart JL, Erlebach E, Glück C, Huang SF, Barrett MJ, Li M, Vinogradov SA, Klohs J, Zarb Y, Keller A, Weber B. Altered hemodynamics and vascular reactivity in a mouse model with severe pericyte deficiency. J Cereb Blood Flow Metab 2022; 43:763-777. [PMID: 36545806 PMCID: PMC10108184 DOI: 10.1177/0271678x221147366] [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: 12/24/2022]
Abstract
Pericytes are the mural cells of the microvascular network that are in close contact with underlying endothelial cells. Endothelial-secreted PDGFB leads to recruitment of pericytes to the vessel wall, but this is disrupted in Pdgfbret/ret mice when the PDGFB retention motif is deleted. This results in severely reduced pericyte coverage on blood vessels. In this study, we investigated vascular abnormalities and hemodynamics in Pdgfbret/ret mice throughout the cerebrovascular network and in different cortical layers by in vivo two-photon microscopy. We confirmed that Pdgfbret/ret mice are severely deficient in pericytes throughout the vascular network, with enlarged brain blood vessels and a reduced number of vessel branches. Red blood cell velocity, linear density, and tube hematocrit were reduced in Pdgfbret/ret mice, which may impair oxygen delivery to the tissue. We also measured intravascular PO2 and found that concentrations were higher in cortical Layer 2/3 in Pdgfbret/ret mice, indicative of reduced blood oxygen extraction. Finally, we found that Pdgfbret/ret mice had a reduced capacity for vasodilation in response to an acetazolamide challenge during functional MRI imaging. Taken together, these results suggest that severe pericyte deficiency can lead to vascular abnormalities and altered cerebral blood flow, reminiscent of pathologies such as arteriovenous malformations.
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Affiliation(s)
- Jillian L Stobart
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, Zurich, Switzerland.,College of Pharmacy, University of Manitoba, Winnipeg, MB, Canada
| | - Eva Erlebach
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, Zurich, Switzerland
| | - Chaim Glück
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, Zurich, Switzerland
| | - Sheng-Fu Huang
- Neuroscience Center, University and ETH Zurich, Zurich, Switzerland.,Department of Neurosurgery, University Hospital Zurich, University of Zurich, Zürich, Switzerland
| | - Matthew Jp Barrett
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, Zurich, Switzerland
| | - Max Li
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, Zurich, Switzerland
| | - Sergei A Vinogradov
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Jan Klohs
- Neuroscience Center, University and ETH Zurich, Zurich, Switzerland.,Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Yvette Zarb
- Neuroscience Center, University and ETH Zurich, Zurich, Switzerland.,Department of Neurosurgery, University Hospital Zurich, University of Zurich, Zürich, Switzerland
| | - Annika Keller
- Neuroscience Center, University and ETH Zurich, Zurich, Switzerland.,Department of Neurosurgery, University Hospital Zurich, University of Zurich, Zürich, Switzerland
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, Zurich, Switzerland
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33
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Haider AA, Rex TS, Wareham LK. cGMP Signaling in the Neurovascular Unit-Implications for Retinal Ganglion Cell Survival in Glaucoma. Biomolecules 2022; 12:1671. [PMID: 36421684 PMCID: PMC9687235 DOI: 10.3390/biom12111671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 11/07/2022] [Accepted: 11/09/2022] [Indexed: 11/16/2022] Open
Abstract
Glaucoma is a progressive age-related disease of the visual system and the leading cause of irreversible blindness worldwide. Currently, intraocular pressure (IOP) is the only modifiable risk factor for the disease, but even as IOP is lowered, the pathology of the disease often progresses. Hence, effective clinical targets for the treatment of glaucoma remain elusive. Glaucoma shares comorbidities with a multitude of vascular diseases, and evidence in humans and animal models demonstrates an association between vascular dysfunction of the retina and glaucoma pathology. Integral to the survival of retinal ganglion cells (RGCs) is functional neurovascular coupling (NVC), providing RGCs with metabolic support in response to neuronal activity. NVC is mediated by cells of the neurovascular unit (NVU), which include vascular cells, glial cells, and neurons. Nitric oxide-cyclic guanosine monophosphate (NO-cGMP) signaling is a prime mediator of NVC between endothelial cells and neurons, but emerging evidence suggests that cGMP signaling is also important in the physiology of other cells of the NVU. NO-cGMP signaling has been implicated in glaucomatous neurodegeneration in humans and mice. In this review, we explore the role of cGMP signaling in the different cell types of the NVU and investigate the potential links between cGMP signaling, breakdown of neurovascular function, and glaucoma pathology.
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Affiliation(s)
| | | | - Lauren K. Wareham
- Vanderbilt Eye Institute, Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, TN 37212, USA
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Renaudin N, Demené C, Dizeux A, Ialy-Radio N, Pezet S, Tanter M. Functional ultrasound localization microscopy reveals brain-wide neurovascular activity on a microscopic scale. Nat Methods 2022; 19:1004-1012. [PMID: 35927475 PMCID: PMC9352591 DOI: 10.1038/s41592-022-01549-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 06/14/2022] [Indexed: 12/02/2022]
Abstract
The advent of neuroimaging has increased our understanding of brain function. While most brain-wide functional imaging modalities exploit neurovascular coupling to map brain activity at millimeter resolutions, the recording of functional responses at microscopic scale in mammals remains the privilege of invasive electrophysiological or optical approaches, but is mostly restricted to either the cortical surface or the vicinity of implanted sensors. Ultrasound localization microscopy (ULM) has achieved transcranial imaging of cerebrovascular flow, up to micrometre scales, by localizing intravenously injected microbubbles; however, the long acquisition time required to detect microbubbles within microscopic vessels has so far restricted ULM application mainly to microvasculature structural imaging. Here we show how ULM can be modified to quantify functional hyperemia dynamically during brain activation reaching a 6.5-µm spatial and 1-s temporal resolution in deep regions of the rat brain.
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Affiliation(s)
- Noémi Renaudin
- Institute Physics for Medicine Paris, INSERM U1273, ESPCI PSL Paris, CNRS UMR 8631, PSL Research University, Paris, France
| | - Charlie Demené
- Institute Physics for Medicine Paris, INSERM U1273, ESPCI PSL Paris, CNRS UMR 8631, PSL Research University, Paris, France
| | - Alexandre Dizeux
- Institute Physics for Medicine Paris, INSERM U1273, ESPCI PSL Paris, CNRS UMR 8631, PSL Research University, Paris, France
| | - Nathalie Ialy-Radio
- Institute Physics for Medicine Paris, INSERM U1273, ESPCI PSL Paris, CNRS UMR 8631, PSL Research University, Paris, France
| | - Sophie Pezet
- Institute Physics for Medicine Paris, INSERM U1273, ESPCI PSL Paris, CNRS UMR 8631, PSL Research University, Paris, France
| | - Mickael Tanter
- Institute Physics for Medicine Paris, INSERM U1273, ESPCI PSL Paris, CNRS UMR 8631, PSL Research University, Paris, France.
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35
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Barkaway A, Attwell D, Korte N. Immune-vascular mural cell interactions: consequences for immune cell trafficking, cerebral blood flow, and the blood-brain barrier. NEUROPHOTONICS 2022; 9:031914. [PMID: 35581998 PMCID: PMC9107322 DOI: 10.1117/1.nph.9.3.031914] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 04/13/2022] [Indexed: 06/15/2023]
Abstract
Brain barriers are crucial sites for cerebral energy supply, waste removal, immune cell migration, and solute exchange, all of which maintain an appropriate environment for neuronal activity. At the capillary level, where the largest area of brain-vascular interface occurs, pericytes adjust cerebral blood flow (CBF) by regulating capillary diameter and maintain the blood-brain barrier (BBB) by suppressing endothelial cell (EC) transcytosis and inducing tight junction expression between ECs. Pericytes also limit the infiltration of circulating leukocytes into the brain where resident microglia confine brain injury and provide the first line of defence against invading pathogens. Brain "waste" is cleared across the BBB into the blood, phagocytosed by microglia and astrocytes, or removed by the flow of cerebrospinal fluid (CSF) through perivascular routes-a process driven by respiratory motion and the pulsation of the heart, arteriolar smooth muscle, and possibly pericytes. "Dirty" CSF exits the brain and is probably drained around olfactory nerve rootlets and via the dural meningeal lymphatic vessels and possibly the skull bone marrow. The brain is widely regarded as an immune-privileged organ because it is accessible to few antigen-primed leukocytes. Leukocytes enter the brain via the meninges, the BBB, and the blood-CSF barrier. Advances in genetic and imaging tools have revealed that neurological diseases significantly alter immune-brain barrier interactions in at least three ways: (1) the brain's immune-privileged status is compromised when pericytes are lost or lymphatic vessels are dysregulated; (2) immune cells release vasoactive molecules to regulate CBF, modulate arteriole stiffness, and can plug and eliminate capillaries which impairs CBF and possibly waste clearance; and (3) immune-vascular interactions can make the BBB leaky via multiple mechanisms, thus aggravating the influx of undesirable substances and cells. Here, we review developments in these three areas and briefly discuss potential therapeutic avenues for restoring brain barrier functions.
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Affiliation(s)
- Anna Barkaway
- University College London, Department of Neuroscience, Physiology and Pharmacology, London, United Kingdom
| | - David Attwell
- University College London, Department of Neuroscience, Physiology and Pharmacology, London, United Kingdom
| | - Nils Korte
- University College London, Department of Neuroscience, Physiology and Pharmacology, London, United Kingdom
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36
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Jehle A, Garaschuk O. The Interplay between cGMP and Calcium Signaling in Alzheimer's Disease. Int J Mol Sci 2022; 23:7048. [PMID: 35806059 PMCID: PMC9266933 DOI: 10.3390/ijms23137048] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 05/31/2022] [Accepted: 06/22/2022] [Indexed: 02/04/2023] Open
Abstract
Cyclic guanosine monophosphate (cGMP) is a ubiquitous second messenger and a key molecule in many important signaling cascades in the body and brain, including phototransduction, olfaction, vasodilation, and functional hyperemia. Additionally, cGMP is involved in long-term potentiation (LTP), a cellular correlate of learning and memory, and recent studies have identified the cGMP-increasing drug Sildenafil as a potential risk modifier in Alzheimer's disease (AD). AD development is accompanied by a net increase in the expression of nitric oxide (NO) synthases but a decreased activity of soluble guanylate cyclases, so the exact sign and extent of AD-mediated imbalance remain unclear. Moreover, human patients and mouse models of the disease present with entangled deregulation of both cGMP and Ca2+ signaling, e.g., causing changes in cGMP-mediated Ca2+ release from the intracellular stores as well as Ca2+-mediated cGMP production. Still, the mechanisms governing such interplay are poorly understood. Here, we review the recent data on mechanisms underlying the brain cGMP signaling and its interconnection with Ca2+ signaling. We also discuss the recent evidence stressing the importance of such interplay for normal brain function as well as in Alzheimer's disease.
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Affiliation(s)
| | - Olga Garaschuk
- Department of Neurophysiology, Institute of Physiology, Eberhard Karls University of Tübingen, 72074 Tübingen, Germany;
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37
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Reeson P, Schager B, Van Sprengel M, Brown CE. Behavioral and Neural Activity-Dependent Recanalization of Plugged Capillaries in the Brain of Adult and Aged Mice. Front Cell Neurosci 2022; 16:876746. [PMID: 35722620 PMCID: PMC9204343 DOI: 10.3389/fncel.2022.876746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 04/12/2022] [Indexed: 11/13/2022] Open
Abstract
The capillaries of the brain, owing to their small diameter and low perfusion pressure, are vulnerable to interruptions in blood flow. These tiny occlusions can have outsized consequences on angioarchitecture and brain function; especially when exacerbated by disease states or accumulate with aging. A distinctive feature of the brain’s microvasculature is the ability for active neurons to recruit local blood flow. The coupling of neural activity to blood flow could play an important role in recanalizing obstructed capillaries. To investigate this idea, we experimentally induced capillary obstructions in mice by injecting fluorescent microspheres and then manipulated neural activity levels though behavioral or pharmacologic approaches. We show that engaging adult and aged mice with 12 h exposure to an enriched environment (group housing, novel objects, exercise wheels) was sufficient to significantly reduce the density of obstructed capillaries throughout the forebrain. In order to more directly manipulate neural activity, we pharmacologically suppressed or increased neuronal activity in the somatosensory cortex. When we suppressed cortical activity, recanalization was impaired given the density of obstructed capillaries was significantly increased. Conversely, increasing cortical activity improved capillary recanalization. Since systemic cardiovascular factors (changes in heart rate, blood pressure) could explain these effects on recanalization, we demonstrate that unilateral manipulations of neural activity through whisker trimming or injection of muscimol, still had significant and hemisphere specific effects on recanalization, even in mice exposed to enrichment where cardiovascular effects would be evident in both hemispheres. In summary, our studies reveal that neural activity bi-directionally regulates the recanalization of obstructed capillaries. Further, we show that stimulating brain activity through behavioral engagement (i.e., environmental enrichment) can promote vascular health throughout the lifespan.
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Affiliation(s)
- Patrick Reeson
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
| | - Ben Schager
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
| | | | - Craig E. Brown
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
- Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada
- *Correspondence: Craig E. Brown,
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38
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Zhu WM, Neuhaus A, Beard DJ, Sutherland BA, DeLuca GC. Neurovascular coupling mechanisms in health and neurovascular uncoupling in Alzheimer's disease. Brain 2022; 145:2276-2292. [PMID: 35551356 PMCID: PMC9337814 DOI: 10.1093/brain/awac174] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 05/05/2022] [Accepted: 05/07/2022] [Indexed: 11/25/2022] Open
Abstract
To match the metabolic demands of the brain, mechanisms have evolved to couple neuronal activity to vasodilation, thus increasing local cerebral blood flow and delivery of oxygen and glucose to active neurons. Rather than relying on metabolic feedback signals such as the consumption of oxygen or glucose, the main signalling pathways rely on the release of vasoactive molecules by neurons and astrocytes, which act on contractile cells. Vascular smooth muscle cells and pericytes are the contractile cells associated with arterioles and capillaries, respectively, which relax and induce vasodilation. Much progress has been made in understanding the complex signalling pathways of neurovascular coupling, but issues such as the contributions of capillary pericytes and astrocyte calcium signal remain contentious. Study of neurovascular coupling mechanisms is especially important as cerebral blood flow dysregulation is a prominent feature of Alzheimer’s disease. In this article we will discuss developments and controversies in the understanding of neurovascular coupling and finish by discussing current knowledge concerning neurovascular uncoupling in Alzheimer’s disease.
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Affiliation(s)
- Winston M Zhu
- Oxford Medical School, University of Oxford, Oxford, UK
| | - Ain Neuhaus
- Acute Stroke Programme, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Daniel J Beard
- Acute Stroke Programme, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.,School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, Australia
| | - Brad A Sutherland
- Tasmanian School of Medicine, College of Health and Medicine, University of Tasmania, Hobart, Australia
| | - Gabriele C DeLuca
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
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39
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Korte N, Ilkan Z, Pearson CL, Pfeiffer T, Singhal P, Rock JR, Sethi H, Gill D, Attwell D, Tammaro P. The Ca2+-gated channel TMEM16A amplifies capillary pericyte contraction and reduces cerebral blood flow after ischemia. J Clin Invest 2022; 132:e154118. [PMID: 35316222 PMCID: PMC9057602 DOI: 10.1172/jci154118] [Citation(s) in RCA: 48] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 03/16/2022] [Indexed: 11/26/2022] Open
Abstract
Pericyte-mediated capillary constriction decreases cerebral blood flow in stroke after an occluded artery is unblocked. The determinants of pericyte tone are poorly understood. We show that a small rise in cytoplasmic Ca2+ concentration ([Ca2+]i) in pericytes activated chloride efflux through the Ca2+-gated anion channel TMEM16A, thus depolarizing the cell and opening voltage-gated calcium channels. This mechanism strongly amplified the pericyte [Ca2+]i rise and capillary constriction evoked by contractile agonists and ischemia. In a rodent stroke model, TMEM16A inhibition slowed the ischemia-evoked pericyte [Ca2+]i rise, capillary constriction, and pericyte death; reduced neutrophil stalling; and improved cerebrovascular reperfusion. Genetic analysis implicated altered TMEM16A expression in poor patient recovery from ischemic stroke. Thus, pericyte TMEM16A is a crucial regulator of cerebral capillary function and a potential therapeutic target for stroke and possibly other disorders of impaired microvascular flow, such as Alzheimer's disease and vascular dementia.
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Affiliation(s)
- Nils Korte
- Department of Neuroscience, Physiology & Pharmacology, University College London, London, United Kingdom
| | - Zeki Ilkan
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - Claire L. Pearson
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - Thomas Pfeiffer
- Department of Neuroscience, Physiology & Pharmacology, University College London, London, United Kingdom
| | - Prabhav Singhal
- Department of Neuroscience, Physiology & Pharmacology, University College London, London, United Kingdom
| | - Jason R. Rock
- Center for Regenerative Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Huma Sethi
- Department of Neurosurgery, National Hospital for Neurology and Neurosurgery, London, United Kingdom
| | - Dipender Gill
- Department of Epidemiology and Biostatistics, St Mary’s Hospital, Imperial College London, London, United Kingdom
| | - David Attwell
- Department of Neuroscience, Physiology & Pharmacology, University College London, London, United Kingdom
| | - Paolo Tammaro
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
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40
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Moccia F, Negri S, Faris P, Angelone T. Targeting endothelial ion signalling to rescue cerebral blood flow in cerebral disorders. Vascul Pharmacol 2022; 145:106997. [DOI: 10.1016/j.vph.2022.106997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/22/2022] [Accepted: 05/02/2022] [Indexed: 10/18/2022]
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41
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Demeulenaere O, Bertolo A, Pezet S, Ialy-Radio N, Osmanski B, Papadacci C, Tanter M, Deffieux T, Pernot M. In vivo whole brain microvascular imaging in mice using transcranial 3D Ultrasound Localization Microscopy. EBioMedicine 2022; 79:103995. [PMID: 35460988 PMCID: PMC9048085 DOI: 10.1016/j.ebiom.2022.103995] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 03/25/2022] [Accepted: 03/25/2022] [Indexed: 11/24/2022] Open
Abstract
Background Non-invasive high-resolution imaging of the cerebral vascular anatomy and function is key for the study of intracranial aneurysms, stenosis, arteriovenous malformations, and stroke, but also neurological pathologies, such as degenerative diseases. Direct visualization of the microvascular networks in the whole brain remains however challenging in vivo. Methods In this work, we performed 3D ultrafast ultrasound localization microscopy (ULM) using a 2D ultrasound matrix array and mapped the whole-brain microvasculature and flow at microscopic resolution in C57Bl6 mice in vivo. Findings We demonstrated that the mouse brain vasculature can be imaged directly through the intact skull at a spatial resolution of 20 µm and over the whole brain depth and at high temporal resolution (750 volumes.s−1). Individual microbubbles were tracked to estimate the flow velocities that ranged from 2 mm.s−1 in arterioles and venules up to 100 mm.s−1 in large vessels. The vascular maps were registered automatically with the Allen atlas in order to extract quantitative vascular parameters such as local flow rates and velocities in regions of interest. Interpretation We show the potential of 3D ULM to provide new insights into whole-brain vascular flow in mice models at unprecedented vascular scale for an in vivo technique. This technology is highly translational and has the potential to become a major tool for the clinical investigation of the cerebral microcirculation. Funding This study was supported by the European Research Council under the European Union's Seventh Framework Program (FP/2007-2013) / ERC Grant Agreement n° 311025 and by the Fondation Bettencourt-Schueller under the program “Physics for Medicine”. We acknowledge the ART (Technological Research Accelerator) biomedical ultrasound program of INSERM.
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Affiliation(s)
- Oscar Demeulenaere
- Physics for Medicine, ESPCI, Inserm, CNRS, Institute of Physics for Medicine Paris, PSL University, ESPCI Paris, 17 rue Moreau, Paris 75012, France
| | - Adrien Bertolo
- Physics for Medicine, ESPCI, Inserm, CNRS, Institute of Physics for Medicine Paris, PSL University, ESPCI Paris, 17 rue Moreau, Paris 75012, France; Iconeus, Paris 75014, France
| | - Sophie Pezet
- Physics for Medicine, ESPCI, Inserm, CNRS, Institute of Physics for Medicine Paris, PSL University, ESPCI Paris, 17 rue Moreau, Paris 75012, France
| | - Nathalie Ialy-Radio
- Physics for Medicine, ESPCI, Inserm, CNRS, Institute of Physics for Medicine Paris, PSL University, ESPCI Paris, 17 rue Moreau, Paris 75012, France
| | | | - Clément Papadacci
- Physics for Medicine, ESPCI, Inserm, CNRS, Institute of Physics for Medicine Paris, PSL University, ESPCI Paris, 17 rue Moreau, Paris 75012, France
| | - Mickael Tanter
- Physics for Medicine, ESPCI, Inserm, CNRS, Institute of Physics for Medicine Paris, PSL University, ESPCI Paris, 17 rue Moreau, Paris 75012, France
| | - Thomas Deffieux
- Physics for Medicine, ESPCI, Inserm, CNRS, Institute of Physics for Medicine Paris, PSL University, ESPCI Paris, 17 rue Moreau, Paris 75012, France
| | - Mathieu Pernot
- Physics for Medicine, ESPCI, Inserm, CNRS, Institute of Physics for Medicine Paris, PSL University, ESPCI Paris, 17 rue Moreau, Paris 75012, France.
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42
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Cerebral Blood Flow in Healthy Subjects with Different Hypnotizability Scores. Brain Sci 2022; 12:brainsci12050558. [PMID: 35624945 PMCID: PMC9138886 DOI: 10.3390/brainsci12050558] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 04/11/2022] [Accepted: 04/26/2022] [Indexed: 12/19/2022] Open
Abstract
Hypnotizability is a cognitive trait associated with differences in the brachial artery flow-mediated dilatation of individuals with high hypnotizability (highs) and low hypnotizability scores (lows). The study investigated possible hypnotizability-related cerebrovascular differences. Among 24 healthy volunteers, the Stanford Hypnotic Susceptibility Scale Form A identified 13 medium-to-lows (med-lows), 11 medium-to-highs (med-highs), and 1 medium hypnotizable. Hypnotizability did not influence the significant changes produced by the trail making task (TMT), mental arithmetic task (MAT), hyperventilation (HVT), and rebreathing (RBT) on heart rate (HR), arterial blood pressure (ABP), and partial pressure of end-tidal CO2 (PETCO2), but moderated the correlations between the changes occurring during tasks with respect to basal conditions (Δ) in ABP and PETCO2 with middle cerebral artery flow velocity (MCAv). In HVT, med-lows exhibited a significant correlation between ΔMCAv and ΔPETCO2, and med-highs showed a significant correlation between ΔABP and ΔMCAv. Cerebrovascular reactivity (CVR) and conductance (ΔCVCi) were significantly correlated with ΔMCAv only in med-lows during HVT and RBT. For the first time, cerebrovascular reactivity related to hypnotizability was investigated, evidencing different correlations among hemodynamic variables in med-highs and med-lows.
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43
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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] [Key Words] [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
| | - 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
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Sancho M, Klug NR, Mughal A, Koide M, Huerta de la Cruz S, Heppner TJ, Bonev AD, Hill-Eubanks D, Nelson MT. Adenosine signaling activates ATP-sensitive K + channels in endothelial cells and pericytes in CNS capillaries. Sci Signal 2022; 15:eabl5405. [PMID: 35349300 DOI: 10.1126/scisignal.abl5405] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The dense network of capillaries composed of capillary endothelial cells (cECs) and pericytes lies in close proximity to all neurons, ideally positioning it to sense neuron- and glial-derived compounds that enhance regional and global cerebral perfusion. The membrane potential (VM) of vascular cells serves as the physiological bridge that translates brain activity into vascular function. In other beds, the ATP-sensitive K+ (KATP) channel regulates VM in vascular smooth muscle, which is absent in the capillary network. Here, with transgenic mice that expressed a dominant-negative mutant of the pore-forming Kir6.1 subunit specifically in brain cECs or pericytes, we demonstrated that KATP channels were present in both cell types and robustly controlled VM. We further showed that the signaling nucleotide adenosine acted through A2A receptors and the Gαs/cAMP/PKA pathway to activate capillary KATP channels. Moreover, KATP channel stimulation in vivo increased cerebral blood flow (CBF), an effect that was blunted by expression of the dominant-negative Kir6.1 mutant in either capillary cell type. These findings establish an important role for KATP channels in cECs and pericytes in the regulation of CBF.
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Affiliation(s)
- Maria Sancho
- Department of Pharmacology, University of Vermont, Burlington, VT 05405-0068, USA
| | - Nicholas R Klug
- Department of Pharmacology, University of Vermont, Burlington, VT 05405-0068, USA
| | - Amreen Mughal
- Department of Pharmacology, University of Vermont, Burlington, VT 05405-0068, USA
| | - Masayo Koide
- Department of Pharmacology, University of Vermont, Burlington, VT 05405-0068, USA.,Vermont Center for Cardiovascular and Brain Health, Larner College of Medicine, University of Vermont, Burlington, VT 05405-0068, USA
| | | | - Thomas J Heppner
- Department of Pharmacology, University of Vermont, Burlington, VT 05405-0068, USA
| | - Adrian D Bonev
- Department of Pharmacology, University of Vermont, Burlington, VT 05405-0068, USA
| | - David Hill-Eubanks
- Department of Pharmacology, University of Vermont, Burlington, VT 05405-0068, USA
| | - Mark T Nelson
- Department of Pharmacology, University of Vermont, Burlington, VT 05405-0068, USA.,Vermont Center for Cardiovascular and Brain Health, Larner College of Medicine, University of Vermont, Burlington, VT 05405-0068, USA.,Division of Cardiovascular Sciences, University of Manchester, Manchester M13 9PL, UK
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Takahashi S. Metabolic Contribution and Cerebral Blood Flow Regulation by Astrocytes in the Neurovascular Unit. Cells 2022; 11:cells11050813. [PMID: 35269435 PMCID: PMC8909328 DOI: 10.3390/cells11050813] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 02/17/2022] [Accepted: 02/24/2022] [Indexed: 12/10/2022] Open
Abstract
The neurovascular unit (NVU) is a conceptual framework that has been proposed to better explain the relationships between the neural cells and blood vessels in the human brain, focused mainly on the brain gray matter. The major components of the NVU are the neurons, astrocytes (astroglia), microvessels, pericytes, and microglia. In addition, we believe that oligodendrocytes should also be included as an indispensable component of the NVU in the white matter. Of all these components, astrocytes in particular have attracted the interest of researchers because of their unique anatomical location; these cells are interposed between the neurons and the microvessels of the brain. Their location suggests that astrocytes might regulate the cerebral blood flow (CBF) in response to neuronal activity, so as to ensure an adequate supply of glucose and oxygen to meet the metabolic demands of the neurons. In fact, the adult human brain, which accounts for only 2% of the entire body weight, consumes approximately 20–25% of the total amount of glucose and oxygen consumed by the whole body. The brain needs a continuous supply of these essential energy sources through the CBF, because there are practically no stores of glucose or oxygen in the brain; both acute and chronic cessation of CBF can adversely affect brain functions. In addition, another important putative function of the NVU is the elimination of heat and waste materials produced by neuronal activity. Recent evidence suggests that astrocytes play pivotal roles not only in supplying glucose, but also fatty acids and amino acids to neurons. Loss of astrocytic support can be expected to lead to malfunction of the NVU as a whole, which underlies numerous neurological disorders. In this review, we shall focus on historical and recent findings with regard to the metabolic contributions of astrocytes in the NVU.
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Affiliation(s)
- Shinichi Takahashi
- Department of Neurology and Stroke, Saitama Medical University International Medical Center, 1397-1 Yamane, Hidaka-shi 350-1298, Japan; ; Tel.: +81-42-984-4111 (ext. 7412) or +81-3-3353-1211 (ext. 62613); Fax: +81-42-984-0664 or +81-3-3357-5445
- Department of Physiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
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Shaw K, Boyd K, Anderle S, Hammond-Haley M, Amin D, Bonnar O, Hall CN. Gradual Not Sudden Change: Multiple Sites of Functional Transition Across the Microvascular Bed. Front Aging Neurosci 2022; 13:779823. [PMID: 35237142 PMCID: PMC8885127 DOI: 10.3389/fnagi.2021.779823] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Accepted: 12/20/2021] [Indexed: 01/03/2023] Open
Abstract
In understanding the role of the neurovascular unit as both a biomarker and target for disease interventions, it is vital to appreciate how the function of different components of this unit change along the vascular tree. The cells of the neurovascular unit together perform an array of vital functions, protecting the brain from circulating toxins and infection, while providing nutrients and clearing away waste products. To do so, the brain's microvasculature dilates to direct energy substrates to active neurons, regulates access to circulating immune cells, and promotes angiogenesis in response to decreased blood supply, as well as pulsating to help clear waste products and maintain the oxygen supply. Different parts of the cerebrovascular tree contribute differently to various aspects of these functions, and previously, it has been assumed that there are discrete types of vessel along the vascular network that mediate different functions. Another option, however, is that the multiple transitions in function that occur across the vascular network do so at many locations, such that vascular function changes gradually, rather than in sharp steps between clearly distinct vessel types. Here, by reference to new data as well as by reviewing historical and recent literature, we argue that this latter scenario is likely the case and that vascular function gradually changes across the network without clear transition points between arteriole, precapillary arteriole and capillary. This is because classically localized functions are in fact performed by wide swathes of the vasculature, and different functional markers start and stop being expressed at different points along the vascular tree. Furthermore, vascular branch points show alterations in their mural cell morphology that suggest functional specializations irrespective of their position within the network. Together this work emphasizes the need for studies to consider where transitions of different functions occur, and the importance of defining these locations, in order to better understand the vascular network and how to target it to treat disease.
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Affiliation(s)
- Kira Shaw
- Sussex Neuroscience, School of Psychology, University of Sussex, Falmer, United Kingdom
| | - Katie Boyd
- Sussex Neuroscience, School of Psychology, University of Sussex, Falmer, United Kingdom
| | - Silvia Anderle
- Sussex Neuroscience, School of Psychology, University of Sussex, Falmer, United Kingdom
| | | | - Davina Amin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Orla Bonnar
- MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital and Harvard Medical School, Charlestown Navy Yard, MA, United States
| | - Catherine N. Hall
- Sussex Neuroscience, School of Psychology, University of Sussex, Falmer, United Kingdom
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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: 82] [Impact Index Per Article: 41.0] [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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