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Sancho M, Klug NR, Harraz OF, Hill-Eubanks D, Nelson MT. Distinct potassium channel types in brain capillary pericytes. Biophys J 2024; 123:2110-2121. [PMID: 38444160 DOI: 10.1016/j.bpj.2024.03.004] [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: 11/15/2023] [Revised: 01/25/2024] [Accepted: 03/01/2024] [Indexed: 03/07/2024] Open
Abstract
Capillaries, composed of electrically coupled endothelial cells and overlying pericytes, constitute the vast majority of blood vessels in the brain. The most arteriole-proximate three to four branches of the capillary bed are covered by α-actin-expressing, contractile pericytes. These mural cells have a distinctive morphology and express different markers compared with their smooth muscle cell (SMC) cousins but share similar excitation-coupling contraction machinery. Despite this similarity, pericytes are considerably more depolarized than SMCs at low intravascular pressures. We have recently shown that pericytes, such as SMCs, possess functional voltage-dependent Ca2+ channels and ATP-sensitive K+ channels. Here, we further investigate the complement of pericyte ion channels, focusing on members of the K+ channel superfamily. Using NG2-DsRed-transgenic mice and diverse configurations of the patch-clamp technique, we demonstrate that pericytes display robust inward-rectifier K+ currents that are primarily mediated by the Kir2 family, based on their unique biophysical characteristics and sensitivity to micromolar concentrations of Ba2+. Moreover, multiple lines of evidence, including characteristic kinetics, sensitivity to specific blockers, biophysical attributes, and distinctive single-channel properties, established the functional expression of two voltage-dependent K+ channels: KV1 and BKCa. Although these three types of channels are also present in SMCs, they exhibit distinctive current density and kinetics profiles in pericytes. Collectively, these findings underscore differences in the operation of shared molecular features between pericytes and SMCs and highlight the potential contribution of these three K+ ion channels in setting pericyte membrane potential, modulating capillary hemodynamics, and regulating cerebral blood flow.
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Affiliation(s)
- Maria Sancho
- Department of Pharmacology, University of Vermont, Burlington, Vermont; Department of Physiology, Faculty of Medicine, Complutense University of Madrid, Madrid, Spain.
| | - Nicholas R Klug
- Department of Pharmacology, University of Vermont, Burlington, Vermont
| | - Osama F Harraz
- Department of Pharmacology, University of Vermont, Burlington, Vermont; Vermont Center for Cardiovascular and Brain Health, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | | | - Mark T Nelson
- Department of Pharmacology, University of Vermont, Burlington, Vermont; Vermont Center for Cardiovascular and Brain Health, Larner College of Medicine, University of Vermont, Burlington, Vermont; Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom.
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2
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Floryanzia S, Lee S, Nance E. Isolation methods and characterization of primary rat neurovascular cells. J Biol Eng 2024; 18:39. [PMID: 38992711 PMCID: PMC11241874 DOI: 10.1186/s13036-024-00434-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2024] [Accepted: 07/02/2024] [Indexed: 07/13/2024] Open
Abstract
BACKGROUND There is significant interest in isolating cells of the blood-brain barrier (BBB) for use in in vitro screening of therapeutics and analyzing cell specific roles in neurovascular pathology. Primary brain cells play an advantageous role in BBB models; however, isolation procedures often do not produce cells at high enough yields for experiments. In addition, although numerous reports provide primary cell isolation methods, the field is lacking in documentation and detail of expected morphological changes that occur throughout culturing and there are minimal troubleshooting resources. Here, we present simplified, robust, and reproducible methodology for isolating astrocytes, pericytes, and endothelial cells, and demonstrate several morphological benchmarks for each cell type throughout the process and culture timeframe. We also analyze common considerations for developing neurovascular cell isolation procedures and recommend solutions for troubleshooting. RESULTS The presented methodology isolated astrocytes, pericytes, and endothelial cells and enabled cell attachment, maturation, and cell viability. We characterized milestones in cell maturation over 12 days in culture, a common timeline for applications of these cell types in BBB models. Phase contrast microscopy was used to show initial cell plating, attachment, and daily growth of isolated cells. Confocal microscopy images were analyzed to determine the identity of cell types and changes to cell morphology. Nuclear staining was also used to show the viability and proliferation of glial cells at four time points. Astrocyte branches became numerous and complex with increased culture time. Microglia, oligodendrocytes, and neurons were present in mixed glial cultures for 12 days, though the percentage of microglia and neurons expectedly decreased after passaging, with microglia demonstrating a less branched morphology. CONCLUSIONS Neurovascular cells can be isolated through our optimized protocols that minimize cell loss and encourage the adhesion and proliferation of isolated cells. By identifying timepoints of viable glia and neurons within an astrocyte-dominant mixed culture, these cells can be used to evaluate drug targeting, uptake studies, and response to pathological stimulus in the neurovascular unit.
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Affiliation(s)
- Sydney Floryanzia
- Department of Chemical Engineering, University of Washington, Seattle, WA, 98195, USA
| | - Seoyoung Lee
- Department of Chemical Engineering, University of Washington, Seattle, WA, 98195, USA
| | - Elizabeth Nance
- Department of Chemical Engineering, University of Washington, Seattle, WA, 98195, USA.
- Department of Bioengineering, University of Washington, Seattle, WA, 98195, USA.
- Department of Molecular Engineering and Sciences, University of Washington, Seattle, WA, 98195, USA.
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3
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Bae SG, Yin GN, Ock J, Suh JK, Ryu JK, Park J. Single-cell transcriptome analysis of cavernous tissues reveals the key roles of pericytes in diabetic erectile dysfunction. eLife 2024; 12:RP88942. [PMID: 38856719 PMCID: PMC11164535 DOI: 10.7554/elife.88942] [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] [Indexed: 06/11/2024] Open
Abstract
Erectile dysfunction (ED) affects a significant proportion of men aged 40-70 and is caused by cavernous tissue dysfunction. Presently, the most common treatment for ED is phosphodiesterase 5 inhibitors; however, this is less effective in patients with severe vascular disease such as diabetic ED. Therefore, there is a need for development of new treatment, which requires a better understanding of the cavernous microenvironment and cell-cell communications under diabetic condition. Pericytes are vital in penile erection; however, their dysfunction due to diabetes remains unclear. In this study, we performed single-cell RNA sequencing to understand the cellular landscape of cavernous tissues and cell type-specific transcriptional changes in diabetic ED. We found a decreased expression of genes associated with collagen or extracellular matrix organization and angiogenesis in diabetic fibroblasts, chondrocytes, myofibroblasts, valve-related lymphatic endothelial cells, and pericytes. Moreover, the newly identified pericyte-specific marker, Limb Bud-Heart (Lbh), in mouse and human cavernous tissues, clearly distinguishing pericytes from smooth muscle cells. Cell-cell interaction analysis revealed that pericytes are involved in angiogenesis, adhesion, and migration by communicating with other cell types in the corpus cavernosum; however, these interactions were highly reduced under diabetic conditions. Lbh expression is low in diabetic pericytes, and overexpression of LBH prevents erectile function by regulating neurovascular regeneration. Furthermore, the LBH-interacting proteins (Crystallin Alpha B and Vimentin) were identified in mouse cavernous pericytes through LC-MS/MS analysis, indicating that their interactions were critical for maintaining pericyte function. Thus, our study reveals novel targets and insights into the pathogenesis of ED in patients with diabetes.
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Affiliation(s)
- Seo-Gyeong Bae
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST)GwangjuRepublic of Korea
| | - Guo Nan Yin
- National Research Center for Sexual Medicine and Department of Urolog, Inha University School of MedicineIncheonRepublic of Korea
| | - Jiyeon Ock
- National Research Center for Sexual Medicine and Department of Urolog, Inha University School of MedicineIncheonRepublic of Korea
| | - Jun-Kyu Suh
- National Research Center for Sexual Medicine and Department of Urolog, Inha University School of MedicineIncheonRepublic of Korea
| | - Ji-Kan Ryu
- National Research Center for Sexual Medicine and Department of Urolog, Inha University School of MedicineIncheonRepublic of Korea
- Program in Biomedical Science & Engineering, Inha UniversityIncheonRepublic of Korea
| | - Jihwan Park
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST)GwangjuRepublic of Korea
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4
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Dupré N, Drieu A, Joutel A. Pathophysiology of cerebral small vessel disease: a journey through recent discoveries. J Clin Invest 2024; 134:e172841. [PMID: 38747292 PMCID: PMC11093606 DOI: 10.1172/jci172841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/19/2024] Open
Abstract
Cerebral small vessel disease (cSVD) encompasses a heterogeneous group of age-related small vessel pathologies that affect multiple regions. Disease manifestations range from lesions incidentally detected on neuroimaging (white matter hyperintensities, small deep infarcts, microbleeds, or enlarged perivascular spaces) to severe disability and cognitive impairment. cSVD accounts for approximately 25% of ischemic strokes and the vast majority of spontaneous intracerebral hemorrhage and is also the most important vascular contributor to dementia. Despite its high prevalence and potentially long therapeutic window, there are still no mechanism-based treatments. Here, we provide an overview of the recent advances in this field. We summarize recent data highlighting the remarkable continuum between monogenic and multifactorial cSVDs involving NOTCH3, HTRA1, and COL4A1/A2 genes. Taking a vessel-centric view, we discuss possible cause-and-effect relationships between risk factors, structural and functional vessel changes, and disease manifestations, underscoring some major knowledge gaps. Although endothelial dysfunction is rightly considered a central feature of cSVD, the contributions of smooth muscle cells, pericytes, and other perivascular cells warrant continued investigation.
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Affiliation(s)
- Nicolas Dupré
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, Paris, France
| | - Antoine Drieu
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, Paris, France
| | - Anne Joutel
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, Paris, France
- GHU-Paris Psychiatrie et Neurosciences, Hôpital Sainte Anne, Paris, France
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5
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Lin S, Landon B, Zhang H, Jin K. Pericyte Dysfunction Contributes to Vascular Cognitive Impairment Induced by Chronic Cerebral Hypoperfusion in Rats. Aging Dis 2024; 15:1357-1372. [PMID: 37611900 PMCID: PMC11081149 DOI: 10.14336/ad.2023.0821-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 08/21/2023] [Indexed: 08/25/2023] Open
Abstract
Vascular cognitive impairment (VCI) encompasses cognitive disorders associated with cerebrovascular disease, often manifesting as white matter lesions (WMLs), irrespective of precise triggers. The integrity of white matter is essential for neural communication and cognitive function maintenance. Persistent cerebral hypoperfusion-induced WMLs are now acknowledged as a key driver of VCI and dementia, though their exact formation mechanism remains unclear. Recent studies link pericyte dysfunction to diverse brain disorders like Alzheimer disease. However, the exact pathological connection between pericyte dysfunction and cognitive impairment in VCI remains unexplored. In this study, we aimed to examine whether pericyte dysfunction could impact WMLs and cognitive impairment in a rat VCI model. Using a rat model of chronic cerebral hypoperfusion-induced VCI through two-vessel occlusion (2VO), we verified that 2VO induced both WMLs and cognitive impairment. Notably, the number of pericytes in the brain was significantly altered after 2VO. Furthermore, we observed significantly increased capillary constrictions at pericyte bodies in the brains of 2VO-induced rats compared to sham-operated rats, accompanied by reduced cerebral blood flow (CBF). To tackle this issue, we administered CGS21680, a specific adenosine A2A subtype receptor agonist, intranasally twice a day for 7 days. We found that rats treated with CGS21680 exhibited a significant increase in CBF at 7 and 14 days after 2VO, compared to the vehicle group. Moreover, capillary lumens beneath pericytes also increased after the CGS21680 treatment. Importantly, the treatment led to substantial improvements in WMLs and cognitive impairment compared to the vehicle group. Our findings suggest a critical role of pericyte dysfunction in WMLs and cognitive impairment within the rat VCI model. This insight contributes to our understanding of pathogenesis and offers prospects for targeted intervention in VCI.
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Affiliation(s)
- Siyang Lin
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, USA.
| | - Benjamin Landon
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, USA.
| | - Hongxia Zhang
- Department of Neurological Surgery, University of California, San Francisco, CA 94158, USA.
| | - Kunlin Jin
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, USA.
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6
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Lin Y, Gahn J, Banerjee K, Dobreva G, Singhal M, Dubrac A, Ola R. Role of endothelial PDGFB in arterio-venous malformations pathogenesis. Angiogenesis 2024; 27:193-209. [PMID: 38070064 PMCID: PMC11021264 DOI: 10.1007/s10456-023-09900-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 11/05/2023] [Indexed: 04/17/2024]
Abstract
Arterial-venous malformations (AVMs) are direct connections between arteries and veins without an intervening capillary bed. Either familial inherited or sporadically occurring, localized pericytes (PCs) drop is among the AVMs' hallmarks. Whether impaired PC coverage triggers AVMs or it is a secondary event is unclear. Here we evaluated the role of the master regulator of PC recruitment, Platelet derived growth factor B (PDGFB) in AVM pathogenesis. Using tamoxifen-inducible deletion of Pdgfb in endothelial cells (ECs), we show that disruption of EC Pdgfb-mediated PC recruitment and maintenance leads to capillary enlargement and organotypic AVM-like structures. These vascular lesions contain non-proliferative hyperplastic, hypertrophic and miss-oriented capillary ECs with an altered capillary EC fate identity. Mechanistically, we propose that PDGFB maintains capillary EC size and caliber to limit hemodynamic changes, thus restricting expression of Krüppel like factor 4 and activation of Bone morphogenic protein, Transforming growth factor β and NOTCH signaling in ECs. Furthermore, our study emphasizes that inducing or activating PDGFB signaling may be a viable therapeutic approach for treating vascular malformations.
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Affiliation(s)
- Yanzhu Lin
- Experimental Pharmacology Mannheim (EPM), European Center for Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Johannes Gahn
- Experimental Pharmacology Mannheim (EPM), European Center for Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Kuheli Banerjee
- Experimental Pharmacology Mannheim (EPM), European Center for Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Gergana Dobreva
- Department of Cardiovascular Genomics and Epigenomics, European Center for Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- German Centre for Cardiovascular Research (DZHK), Heidelberg, Germany
| | - Mahak Singhal
- Laboratory of AngioRhythms, European Center for Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Alexandre Dubrac
- Centre de Recherche, CHU St. Justine, Montreal, QC, H3T 1C5, Canada
- Département de Pathologie et Biologie Cellulaire, Université de Montréal, Montreal, QC, H3T 1J4, Canada
| | - Roxana Ola
- Experimental Pharmacology Mannheim (EPM), European Center for Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.
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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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Coursier D, Calvo F. CAFs vs. TECs: when blood feuds fuel cancer progression, dissemination and therapeutic resistance. Cell Oncol (Dordr) 2024:10.1007/s13402-024-00931-z. [PMID: 38453816 DOI: 10.1007/s13402-024-00931-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/23/2024] [Indexed: 03/09/2024] Open
Abstract
Neoplastic progression involves complex interactions between cancer cells and the surrounding stromal milieu, fostering microenvironments that crucially drive tumor progression and dissemination. Of these stromal constituents, cancer-associated fibroblasts (CAFs) emerge as predominant inhabitants within the tumor microenvironment (TME), actively shaping multiple facets of tumorigenesis, including cancer cell proliferation, invasiveness, and immune evasion. Notably, CAFs also orchestrate the production of pro-angiogenic factors, fueling neovascularization to sustain the metabolic demands of proliferating cancer cells. Moreover, CAFs may also directly or indirectly affect endothelial cell behavior and vascular architecture, which may impact in tumor progression and responses to anti-cancer interventions. Conversely, tumor endothelial cells (TECs) exhibit a corrupted state that has been shown to affect cancer cell growth and inflammation. Both CAFs and TECs are emerging as pivotal regulators of the TME, engaging in multifaceted biological processes that significantly impact cancer progression, dissemination, and therapeutic responses. Yet, the intricate interplay between these stromal components and the orchestrated functions of each cell type remains incompletely elucidated. In this review, we summarize the current understanding of the dynamic interrelationships between CAFs and TECs, discussing the challenges and prospects for leveraging their interactions towards therapeutic advancements in cancer.
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Affiliation(s)
- Diane Coursier
- Instituto de Biomedicina y Biotecnología de Cantabria (Consejo Superior de Investigaciones Científicas, Universidad de Cantabria), Santander, Spain
| | - Fernando Calvo
- Instituto de Biomedicina y Biotecnología de Cantabria (Consejo Superior de Investigaciones Científicas, Universidad de Cantabria), Santander, Spain.
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9
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Mateus Gonçalves L, Andrade Barboza C, Almaça J. Diabetes as a Pancreatic Microvascular Disease-A Pericytic Perspective. J Histochem Cytochem 2024; 72:131-148. [PMID: 38454609 PMCID: PMC10956440 DOI: 10.1369/00221554241236535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Accepted: 02/09/2024] [Indexed: 03/09/2024] Open
Abstract
Diabetes is not only an endocrine but also a vascular disease. Vascular defects are usually seen as consequence of diabetes. However, at the level of the pancreatic islet, vascular alterations have been described before symptom onset. Importantly, the cellular and molecular mechanisms underlying these early vascular defects have not been identified, neither how these could impact the function of islet endocrine cells. In this review, we will discuss the possibility that dysfunction of the mural cells of the microvasculature-known as pericytes-underlies vascular defects observed in islets in pre-symptomatic stages. Pericytes are crucial for vascular homeostasis throughout the body, but their physiological and pathophysiological functions in islets have only recently started to be explored. A previous study had already raised interest in the "microvascular" approach to this disease. With our increased understanding of the crucial role of the islet microvasculature for glucose homeostasis, here we will revisit the vascular aspects of islet function and how their deregulation could contribute to diabetes pathogenesis, focusing in particular on type 1 diabetes (T1D).
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Affiliation(s)
- Luciana Mateus Gonçalves
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida
| | - Catarina Andrade Barboza
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida
| | - Joana Almaça
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, Florida
- Molecular and Cellular Pharmacology Graduate Program, University of Miami Miller School of Medicine, Miami, Florida
- Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, Florida
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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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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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14
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Brown LS, King NE, Courtney JM, Gasperini RJ, Foa L, Howells DW, Sutherland BA. Brain pericytes in culture display diverse morphological and functional phenotypes. Cell Biol Toxicol 2023; 39:2999-3014. [PMID: 37322257 PMCID: PMC10693527 DOI: 10.1007/s10565-023-09814-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 05/23/2023] [Indexed: 06/17/2023]
Abstract
Pericytes play several important functions in the neurovascular unit including contractile control of capillaries, maintenance of the BBB, regulation of angiogenesis, and neuroinflammation. There exists a continuum of pericyte subtypes along the vascular tree which exhibit both morphological and transcriptomic differences. While different functions have been associated with the pericyte subtypes in vivo, numerous recent publications have used a primary human brain vascular pericytes (HBVP) cell line where this pericyte heterogeneity has not been considered. Here, we used primary HBVP cultures, high-definition imaging, cell motility tracking, and immunocytochemistry to characterise morphology, protein expression, and contractile behaviour to determine whether heterogeneity of pericytes also exists in cultures. We identified five distinct morphological subtypes that were defined using both qualitative criteria and quantitative shape analysis. The proportion of each subtype present within the culture changed as passage number increased, but pericytes did not change morphological subtype over short time periods. The rate and extent of cellular and membrane motility differed across the subtypes. Immunocytochemistry revealed differential expression of alpha-smooth muscle actin (αSMA) across subtypes. αSMA is essential for cell contractility, and consequently, only subtypes with high αSMA expression contracted in response to physiological vasoconstrictors endothelin-1 (ET1) and noradrenaline (NA). We conclude that there are distinct morphological subtypes in HBVP culture, which display different behaviours. This has significance for the use of HBVP when modelling pericyte physiology in vitro where relevance to in vivo pericyte subtypes along the vascular tree must be considered.
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Affiliation(s)
- Lachlan S Brown
- Tasmanian School of Medicine, College of Health and Medicine, University of Tasmania, Level 4 Medical Sciences Precinct, 17 Liverpool St, Hobart, TAS, 7000, Australia
| | - Natalie E King
- Tasmanian School of Medicine, College of Health and Medicine, University of Tasmania, Level 4 Medical Sciences Precinct, 17 Liverpool St, Hobart, TAS, 7000, Australia
| | - Jo-Maree Courtney
- Tasmanian School of Medicine, College of Health and Medicine, University of Tasmania, Level 4 Medical Sciences Precinct, 17 Liverpool St, Hobart, TAS, 7000, Australia
| | - Robert J Gasperini
- Tasmanian School of Medicine, College of Health and Medicine, University of Tasmania, Level 4 Medical Sciences Precinct, 17 Liverpool St, Hobart, TAS, 7000, Australia
| | - Lisa Foa
- Tasmanian School of Medicine, College of Health and Medicine, University of Tasmania, Level 4 Medical Sciences Precinct, 17 Liverpool St, Hobart, TAS, 7000, Australia
- School of Psychological Sciences, College of Health and Medicine, University of Tasmania, Hobart, TAS, Australia
| | - David W Howells
- Tasmanian School of Medicine, College of Health and Medicine, University of Tasmania, Level 4 Medical Sciences Precinct, 17 Liverpool St, Hobart, TAS, 7000, Australia
| | - Brad A Sutherland
- Tasmanian School of Medicine, College of Health and Medicine, University of Tasmania, Level 4 Medical Sciences Precinct, 17 Liverpool St, Hobart, TAS, 7000, Australia.
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15
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Ting KK, Coleman P, Kim HJ, Zhao Y, Mulangala J, Cheng NC, Li W, Gunatilake D, Johnstone DM, Loo L, Neely GG, Yang P, Götz J, Vadas MA, Gamble JR. Vascular senescence and leak are features of the early breakdown of the blood-brain barrier in Alzheimer's disease models. GeroScience 2023; 45:3307-3331. [PMID: 37782439 PMCID: PMC10643714 DOI: 10.1007/s11357-023-00927-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 08/27/2023] [Indexed: 10/03/2023] Open
Abstract
Alzheimer's disease (AD) is an age-related disease, with loss of integrity of the blood-brain barrier (BBB) being an early feature. Cellular senescence is one of the reported nine hallmarks of aging. Here, we show for the first time the presence of senescent cells in the vasculature in AD patients and mouse models of AD. Senescent endothelial cells and pericytes are present in APP/PS1 transgenic mice but not in wild-type littermates at the time of amyloid deposition. In vitro, senescent endothelial cells display altered VE-cadherin expression and loss of cell junction formation and increased permeability. Consistent with this, senescent endothelial cells in APP/PS1 mice are present at areas of vascular leak that have decreased claudin-5 and VE-cadherin expression confirming BBB breakdown. Furthermore, single cell sequencing of endothelial cells from APP/PS1 transgenic mice confirms that adhesion molecule pathways are among the most highly altered pathways in these cells. At the pre-plaque stage, the vasculature shows significant signs of breakdown, with a general loss of VE-cadherin, leakage within the microcirculation, and obvious pericyte perturbation. Although senescent vascular cells were not directly observed at sites of vascular leak, senescent cells were close to the leak area. Thus, we would suggest in AD that there is a progressive induction of senescence in constituents of the neurovascular unit contributing to an increasing loss of vascular integrity. Targeting the vasculature early in AD, either with senolytics or with drugs that improve the integrity of the BBB may be valid therapeutic strategies.
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Affiliation(s)
- Ka Ka Ting
- Vascular Biology Program, Centenary Institute, Camperdown, NSW, Australia.
- School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia.
| | - Paul Coleman
- Vascular Biology Program, Centenary Institute, Camperdown, NSW, Australia
- School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia
| | - Hani Jieun Kim
- Computational Systems Biology Group, Children's Medical Research Institute, Faculty of Medicine and Health, The University of Sydney, Westmead, NSW, 2145, Australia
| | - Yang Zhao
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023, Jiangsu, China
| | - Jocelyne Mulangala
- Vascular Biology Program, Centenary Institute, Camperdown, NSW, Australia
| | - Ngan Ching Cheng
- Vascular Biology Program, Centenary Institute, Camperdown, NSW, Australia
| | - Wan Li
- Department of General Surgery, Jiangsu Province Hospital of Chinese Medicine, Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, 210029, China
| | - Dilini Gunatilake
- Vascular Biology Program, Centenary Institute, Camperdown, NSW, Australia
| | - Daniel M Johnstone
- School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia
- School of Biomedical Sciences & Pharmacy, University of Newcastle, Callaghan, NSW, Australia
| | - Lipin Loo
- Charles Perkins Centre, Dr. John and Anne Chong Lab for Functional Genomics, Centenary Institute, & School of Life and Environmental Sciences, University of Sydney, Camperdown, NSW, Australia
| | - G Gregory Neely
- Charles Perkins Centre, Dr. John and Anne Chong Lab for Functional Genomics, Centenary Institute, & School of Life and Environmental Sciences, University of Sydney, Camperdown, NSW, Australia
| | - Pengyi Yang
- Computational Systems Biology Group, Children's Medical Research Institute, Faculty of Medicine and Health, The University of Sydney, Westmead, NSW, 2145, Australia
| | - Jürgen Götz
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Australia
| | - Mathew A Vadas
- Vascular Biology Program, Centenary Institute, Camperdown, NSW, Australia
- Heart Research Institute, Sydney, NSW, Australia
| | - Jennifer R Gamble
- Vascular Biology Program, Centenary Institute, Camperdown, NSW, Australia.
- School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia.
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16
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Wakid M, Almeida D, Aouabed Z, Rahimian R, Davoli MA, Yerko V, Leonova-Erko E, Richard V, Zahedi R, Borchers C, Turecki G, Mechawar N. Universal method for the isolation of microvessels from frozen brain tissue: A proof-of-concept multiomic investigation of the neurovasculature. Brain Behav Immun Health 2023; 34:100684. [PMID: 37822873 PMCID: PMC10562768 DOI: 10.1016/j.bbih.2023.100684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 08/29/2023] [Accepted: 09/06/2023] [Indexed: 10/13/2023] Open
Abstract
The neurovascular unit, comprised of vascular cell types that collectively regulate cerebral blood flow to meet the needs of coupled neurons, is paramount for the proper function of the central nervous system. The neurovascular unit gatekeeps blood-brain barrier properties, which experiences impairment in several central nervous system diseases associated with neuroinflammation and contributes to pathogenesis. To better understand function and dysfunction at the neurovascular unit and how it may confer inflammatory processes within the brain, isolation and characterization of the neurovascular unit is needed. Here, we describe a singular, standardized protocol to enrich and isolate microvessels from archived snap-frozen human and frozen mouse cerebral cortex using mechanical homogenization and centrifugation-separation that preserves the structural integrity and multicellular composition of microvessel fragments. For the first time, microvessels are isolated from postmortem ventromedial prefrontal cortex tissue and are comprehensively investigated as a structural unit using both RNA sequencing and Liquid Chromatography with tandem mass spectrometry (LC-MS/MS). Both the transcriptome and proteome are obtained and compared, demonstrating that the isolated brain microvessel is a robust model for the NVU and can be used to generate highly informative datasets in both physiological and disease contexts.
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Affiliation(s)
- Marina Wakid
- McGill Group for Suicide Studies, Douglas Research Centre, Montréal, Quebec, Canada
- Integrated Program in Neuroscience, McGill University, Montréal, Quebec, Canada
| | - Daniel Almeida
- McGill Group for Suicide Studies, Douglas Research Centre, Montréal, Quebec, Canada
- Integrated Program in Neuroscience, McGill University, Montréal, Quebec, Canada
| | - Zahia Aouabed
- McGill Group for Suicide Studies, Douglas Research Centre, Montréal, Quebec, Canada
| | - Reza Rahimian
- McGill Group for Suicide Studies, Douglas Research Centre, Montréal, Quebec, Canada
| | | | - Volodymyr Yerko
- McGill Group for Suicide Studies, Douglas Research Centre, Montréal, Quebec, Canada
| | - Elena Leonova-Erko
- McGill Group for Suicide Studies, Douglas Research Centre, Montréal, Quebec, Canada
| | - Vincent Richard
- Segal Cancer Proteomics Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, McGill University, Montréal, Quebec, Canada
| | - René Zahedi
- Segal Cancer Proteomics Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, McGill University, Montréal, Quebec, Canada
| | - Christoph Borchers
- Segal Cancer Proteomics Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, McGill University, Montréal, Quebec, Canada
| | - Gustavo Turecki
- McGill Group for Suicide Studies, Douglas Research Centre, Montréal, Quebec, Canada
- Integrated Program in Neuroscience, McGill University, Montréal, Quebec, Canada
- Department of Psychiatry, McGill University, Montréal, Quebec, Canada
| | - Naguib Mechawar
- McGill Group for Suicide Studies, Douglas Research Centre, Montréal, Quebec, Canada
- Integrated Program in Neuroscience, McGill University, Montréal, Quebec, Canada
- Department of Psychiatry, McGill University, Montréal, Quebec, Canada
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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: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 09/23/2023] [Accepted: 09/25/2023] [Indexed: 10/03/2023]
Abstract
Retinal ganglion cells, the neurons that die in glaucoma, are endowed with a high metabolism requiring optimal provision of oxygen and nutrients to sustain their activity. The timely regulation of blood flow is, therefore, essential to supply firing neurons in active areas with the oxygen and glucose they need for energy. Many glaucoma patients suffer from vascular deficits including reduced blood flow, impaired autoregulation, neurovascular coupling dysfunction, and blood-retina/brain-barrier breakdown. These processes are tightly regulated by a community of cells known as the neurovascular unit comprising neurons, endothelial cells, pericytes, Müller cells, astrocytes, and microglia. In this review, the neurovascular unit takes center stage as we examine the ability of its members to regulate neurovascular interactions and how their function might be altered during glaucomatous stress. Pericytes receive special attention based on recent data demonstrating their key role in the regulation of neurovascular coupling in physiological and pathological conditions. Of particular interest is the discovery and characterization of tunneling nanotubes, thin actin-based conduits that connect distal pericytes, which play essential roles in the complex spatial and temporal distribution of blood within the retinal capillary network. We discuss cellular and molecular mechanisms of neurovascular interactions and their pathophysiological implications, while highlighting opportunities to develop strategies for vascular protection and regeneration to improve functional outcomes in glaucoma.
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Affiliation(s)
- Luis Alarcon-Martinez
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada; Centre for Eye Research Australia, University of Melbourne, Melbourne, Australia
| | - Yukihiro Shiga
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Deborah Villafranca-Baughman
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Jorge L Cueva Vargas
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Isaac A Vidal Paredes
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Heberto Quintero
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Brad Fortune
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Healthy, Portland, OR, USA
| | - Helen Danesh-Meyer
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Adriana Di Polo
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada.
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18
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Sandow SL, Wilson SM, Leo MD. Editorial: The role of pericytes in physiology and pathophysiology. Front Physiol 2023; 14:1306031. [PMID: 37929215 PMCID: PMC10625401 DOI: 10.3389/fphys.2023.1306031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 10/10/2023] [Indexed: 11/07/2023] Open
Affiliation(s)
- Shaun L. Sandow
- Biomedical Science, School of Health, University of the Sunshine Coast, Maroochydore, and Center for Clinical Research, Faculty of Medicine, University of Queensland, Brisbane, QLD, Australia
| | - Sean M. Wilson
- Division of Pharmacology, School of Medicine, Loma Linda University, Loma Linda, CA, United States
| | - M. Dennis Leo
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN, United States
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19
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Hein M, Mehnert A, Freund KB, Yu DY, Balaratnasingam C. Variability in Capillary Perfusion Is Increased in Regions of Retinal Ischemia Due to Branch Retinal Vein Occlusion. Invest Ophthalmol Vis Sci 2023; 64:30. [PMID: 37856113 PMCID: PMC10615145 DOI: 10.1167/iovs.64.13.30] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 09/23/2023] [Indexed: 10/20/2023] Open
Abstract
Purpose To investigate alterations in macular perfusion variability due to branch retinal vein occlusion (BRVO) using a novel approach based on optical coherence tomography angiography (OCTA) coefficient of variation (CoV) analysis. Methods Thirteen eyes of 13 patients with macular ischemia due to BRVO were studied. Multiple consecutive en face OCTA images were acquired. Bias field correction, spatial alignment, and normalization of intensities across the images were performed followed by pixelwise computation of standard deviation divided by the mean to generate a CoV map. Region of interest-based CoV values, derived from this map, for arterioles, venules, and the microvasculature were compared between regions with macular ischemia and control areas of the same eye. Control areas were regions of the same macula that were not affected by the BRVO and had normal retinal vascular structure as seen on multimodal imaging and normal retinal vascular density measurements as quantified using OCTA. Results CoV increased by a mean value of 17.6% within the microvasculature of ischemic regions compared to the control microvasculature (P < 0.0001). CoV measurements of microvasculature were consistently greater in the ischemic area of all 13 eyes compared to control. There were no differences in CoV measurements between ischemic and control areas for arterioles (P = 0.13) and venules (P = 1.0). Conclusions Greater variability in microvasculature perfusion occurs at sites of macular ischemia due to BRVO. We report a novel way for quantifying macular perfusion variability using OCTA. This technique may have applicability for studying the pathophysiology of other retinal vascular diseases.
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Affiliation(s)
- Martin Hein
- Lions Eye Institute, Nedlands, Western Australia, Australia
- Centre for Ophthalmology and Visual Science, University of Western Australia, Perth, Australia
| | - Andrew Mehnert
- Lions Eye Institute, Nedlands, Western Australia, Australia
- Centre for Ophthalmology and Visual Science, University of Western Australia, Perth, Australia
| | - K. Bailey Freund
- Vitreous Retina Macula Consultants of New York, New York, New York, United States
- Department of Ophthalmology, New York University Grossman School of Medicine, New York, New York, United States
| | - Dao-Yi Yu
- Lions Eye Institute, Nedlands, Western Australia, Australia
- Centre for Ophthalmology and Visual Science, University of Western Australia, Perth, Australia
| | - Chandrakumar Balaratnasingam
- Lions Eye Institute, Nedlands, Western Australia, Australia
- Centre for Ophthalmology and Visual Science, University of Western Australia, Perth, Australia
- Department of Ophthalmology, Sir Charles Gairdner Hospital, Western Australia, Perth, Australia
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20
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Yang Y, Chen Y, Pei P, Fan Y, Wang S, Zhang H, Zhao D, Qian BZ, Zhang F. Fluorescence-amplified nanocrystals in the second near-infrared window for in vivo real-time dynamic multiplexed imaging. NATURE NANOTECHNOLOGY 2023; 18:1195-1204. [PMID: 37349506 DOI: 10.1038/s41565-023-01422-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Accepted: 05/16/2023] [Indexed: 06/24/2023]
Abstract
Optical imaging in the second near-infrared window (NIR-II, 1,000-1,700 nm) holds great promise for non-invasive in vivo detection. However, real-time dynamic multiplexed imaging remains challenging due to the lack of available fluorescence probes and multiplexing techniques in the ideal NIR-IIb (1,500-1,700 nm) 'deep-tissue-transparent' sub-window. Here we report on thulium-based cubic-phase downshifting nanoparticles (α-TmNPs) with 1,632 nm fluorescence amplification. This strategy was also validated for the fluorescence enhancement of nanoparticles doped with NIR-II Er3+ (α-ErNPs) or Ho3+ (α-HoNPs). In parallel, we developed a simultaneous dual-channel imaging system with high spatiotemporal synchronization and accuracy. The NIR-IIb α-TmNPs and α-ErNPs facilitated the non-invasive real-time dynamic multiplexed imaging of cerebrovascular vasomotion activity and the single-cell-level neutrophil behaviour in mouse subcutaneous tissue and ischaemic stroke model.
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Affiliation(s)
- Yiwei Yang
- Department of Chemistry, State Key Laboratory of Molecular Engineering of Polymers and iChem, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai, China
| | - Ying Chen
- Department of Chemistry, State Key Laboratory of Molecular Engineering of Polymers and iChem, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai, China
| | - Peng Pei
- Department of Chemistry, State Key Laboratory of Molecular Engineering of Polymers and iChem, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai, China
| | - Yong Fan
- Department of Chemistry, State Key Laboratory of Molecular Engineering of Polymers and iChem, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai, China.
| | - Shangfeng Wang
- Department of Chemistry, State Key Laboratory of Molecular Engineering of Polymers and iChem, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai, China
| | - Hongxin Zhang
- Department of Chemistry, State Key Laboratory of Molecular Engineering of Polymers and iChem, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai, China
| | - Dongyuan Zhao
- Department of Chemistry, State Key Laboratory of Molecular Engineering of Polymers and iChem, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai, China
| | - Bin-Zhi Qian
- Human Phenome Institute, Zhangjiang Fudan International Innovation Center, Fudan University, Shanghai, China
- Centre for Reproductive Health, College of Medicine and Veterinary Medicine, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, UK
| | - Fan Zhang
- Department of Chemistry, State Key Laboratory of Molecular Engineering of Polymers and iChem, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai, China.
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21
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Ferris HR, Hill-Eubanks DC, Nelson MT, Wellman GC, Koide M. Epidermal growth factor receptors in vascular endothelial cells contribute to functional hyperemia in the brain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.15.557981. [PMID: 37745396 PMCID: PMC10516026 DOI: 10.1101/2023.09.15.557981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
Functional hyperemia - activity-dependent increases in local blood perfusion - underlies the on-demand delivery of blood to regions of enhanced neuronal activity, a process that is crucial for brain health. Importantly, functional hyperemia deficits have been linked to multiple dementia risk factors, including aging, chronic hypertension, and cerebral small vessel disease (cSVD). We previously reported crippled functional hyperemia in a mouse model of genetic cSVD that was likely caused by depletion of phosphatidylinositol 4,5-bisphosphate (PIP2) in capillary endothelial cells (EC) downstream of impaired epidermal growth factor receptor (EGFR) signaling. Here, using EC-specific EGFR-knockout (KO) mice, we directly examined the role of endothelial EGFR signaling in functional hyperemia, assessed by measuring increases in cerebral blood flow in response to contralateral whisker stimulation using laser Doppler flowmetry. Molecular characterizations showed that EGFR expression was dramatically decreased in freshly isolated capillaries from EC-EGFR-KO mice, as expected. Notably, whisker stimulation-induced functional hyperemia was significantly impaired in these mice, an effect that was rescued by exogenous administration of PIP2, but not by the EGFR ligand, HB-EGF. These data suggest that the deletion of the EGFR specifically in ECs depletes PIP2 and attenuates functional hyperemia, underscoring the central role of the endothelial EGFR signaling in cerebral blood flow regulation.
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Affiliation(s)
- Hannah R. Ferris
- Department of Pharmacology, Larner College of Medicine University of Vermont, Burlington, VT, USA
| | - David C. Hill-Eubanks
- Department of Pharmacology, Larner College of Medicine University of Vermont, Burlington, VT, USA
| | - Mark T. Nelson
- Department of Pharmacology, Larner College of Medicine University of Vermont, Burlington, VT, USA
- Vermont Center for Cardiovascular and Brain Health, Larner College of Medicine University of Vermont, Burlington, VT, USA
- Division of Cardiovascular Sciences, University of Manchester, Manchester, UK
| | - George C. Wellman
- Department of Pharmacology, Larner College of Medicine University of Vermont, Burlington, VT, USA
| | - Masayo Koide
- Department of Pharmacology, Larner College of Medicine University of Vermont, Burlington, VT, USA
- Vermont Center for Cardiovascular and Brain Health, Larner College of Medicine University of Vermont, Burlington, VT, USA
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22
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Li C, Chen S, Siedhoff HR, Grant D, Liu P, Balderrama A, Jackson M, Zuckerman A, Greenlief CM, Kobeissy F, Wang KW, DePalma RG, Cernak I, Cui J, Gu Z. Low-intensity open-field blast exposure effects on neurovascular unit ultrastructure in mice. Acta Neuropathol Commun 2023; 11:144. [PMID: 37674234 PMCID: PMC10481586 DOI: 10.1186/s40478-023-01636-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Accepted: 08/14/2023] [Indexed: 09/08/2023] Open
Abstract
Mild traumatic brain injury (mTBI) induced by low-intensity blast (LIB) is a serious health problem affecting military service members and veterans. Our previous reports using a single open-field LIB mouse model showed the absence of gross microscopic damage or necrosis in the brain, while transmission electron microscopy (TEM) identified ultrastructural abnormalities of myelin sheaths, mitochondria, and synapses. The neurovascular unit (NVU), an anatomical and functional system with multiple components, is vital for the regulation of cerebral blood flow and cellular interactions. In this study, we delineated ultrastructural abnormalities affecting the NVU in mice with LIB exposure quantitatively and qualitatively. Luminal constrictive irregularities were identified at 7 days post-injury (DPI) followed by dilation at 30 DPI along with degeneration of pericytes. Quantitative proteomic analysis identified significantly altered vasomotor-related proteins at 24 h post-injury. Endothelial cell, basement membrane and astrocyte end-foot swellings, as well as vacuole formations, occurred in LIB-exposed mice, indicating cellular edema. Structural abnormalities of tight junctions and astrocyte end-foot detachment from basement membranes were also noted. These ultrastructural findings demonstrate that LIB induces multiple-component NVU damage. Prevention of NVU damage may aid in identifying therapeutic targets to mitigate the effects of primary brain blast injury.
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Affiliation(s)
- Chao Li
- Department of Pathology & Anatomical Sciences, University of Missouri School of Medicine, One Hospital Drive, Medical Science Building, M741, Columbia, MO, 65212, USA
- Department of Rehabilitation Medicine, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, 510630, China
| | - Shanyan Chen
- Department of Pathology & Anatomical Sciences, University of Missouri School of Medicine, One Hospital Drive, Medical Science Building, M741, Columbia, MO, 65212, USA
- Truman VA Hospital Research Service, Columbia, MO, 65201, USA
| | - Heather R Siedhoff
- Department of Pathology & Anatomical Sciences, University of Missouri School of Medicine, One Hospital Drive, Medical Science Building, M741, Columbia, MO, 65212, USA
- Truman VA Hospital Research Service, Columbia, MO, 65201, USA
| | - DeAna Grant
- Electron Microscopy Core Facility, University of Missouri, Columbia, MO, 65211, USA
| | - Pei Liu
- Charles W. Gehrke Proteomic Center, University of Missouri, Columbia, MO, 65211, USA
| | - Ashley Balderrama
- Department of Pathology & Anatomical Sciences, University of Missouri School of Medicine, One Hospital Drive, Medical Science Building, M741, Columbia, MO, 65212, USA
- Truman VA Hospital Research Service, Columbia, MO, 65201, USA
| | - Marcus Jackson
- Department of Pathology & Anatomical Sciences, University of Missouri School of Medicine, One Hospital Drive, Medical Science Building, M741, Columbia, MO, 65212, USA
| | - Amitai Zuckerman
- Department of Pathology & Anatomical Sciences, University of Missouri School of Medicine, One Hospital Drive, Medical Science Building, M741, Columbia, MO, 65212, USA
- Truman VA Hospital Research Service, Columbia, MO, 65201, USA
| | - C Michael Greenlief
- Charles W. Gehrke Proteomic Center, University of Missouri, Columbia, MO, 65211, USA
| | - Firas Kobeissy
- Department of Neurobiology, Center for Neurotrauma, Multiomics & Biomarkers (CNMB), Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA, 30310-1458, USA
- Atlanta VA Medical and Rehab Center, Decatur, GA, 30033, USA
| | - Kevin W Wang
- Department of Neurobiology, Center for Neurotrauma, Multiomics & Biomarkers (CNMB), Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA, 30310-1458, USA
- Atlanta VA Medical and Rehab Center, Decatur, GA, 30033, USA
| | - Ralph G DePalma
- Office of Research and Development, Department of Veterans Affairs, Washington, DC, 20420, USA
- Department of Surgery, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA
| | - Ibolja Cernak
- Department of Biomedical Sciences, Mercer University School of Medicine, Macon, GA, 31207, USA
| | - Jiankun Cui
- Department of Pathology & Anatomical Sciences, University of Missouri School of Medicine, One Hospital Drive, Medical Science Building, M741, Columbia, MO, 65212, USA
- Truman VA Hospital Research Service, Columbia, MO, 65201, USA
| | - Zezong Gu
- Department of Pathology & Anatomical Sciences, University of Missouri School of Medicine, One Hospital Drive, Medical Science Building, M741, Columbia, MO, 65212, USA.
- Truman VA Hospital Research Service, Columbia, MO, 65201, USA.
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23
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Mateus Gonçalves L, Fahd Qadir MM, Boulina M, Makhmutova M, Pereira E, Almaça J. Pericyte dysfunction and impaired vasomotion are hallmarks of islets during the pathogenesis of type 1 diabetes. Cell Rep 2023; 42:112913. [PMID: 37531253 PMCID: PMC10529889 DOI: 10.1016/j.celrep.2023.112913] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 05/26/2023] [Accepted: 07/16/2023] [Indexed: 08/04/2023] Open
Abstract
Pancreatic islets are endocrine organs that depend on their microvasculature to function. Along with endothelial cells, pericytes comprise the islet microvascular network. These mural cells are crucial for microvascular stability and function, but it is not known if/how they are affected during the development of type 1 diabetes (T1D). Here, we investigate islet pericyte density, phenotype, and function using living pancreas slices from donors without diabetes, donors with a single T1D-associated autoantibody (GADA+), and recent onset T1D cases. Our data show that islet pericyte and capillary responses to vasoactive stimuli are impaired early on in T1D. Microvascular dysfunction is associated with a switch in the phenotype of islet pericytes toward myofibroblasts. Using publicly available RNA sequencing (RNA-seq) data, we further found that transcriptional alterations related to endothelin-1 signaling and vascular and extracellular matrix (ECM) remodeling are hallmarks of single autoantibody (Aab)+ donor pancreata. Our data show that microvascular dysfunction is present at early stages of islet autoimmunity.
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Affiliation(s)
- Luciana Mateus Gonçalves
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Mirza Muhammad Fahd Qadir
- Section of Endocrinology and Metabolism, John W. Deming Department of Medicine, Tulane University School of Medicine, New Orleans, LA, USA; Southeast Louisiana Veterans Health Care System, New Orleans, LA, USA; Tulane Center of Excellence in Sex-Based Biology & Medicine, New Orleans, LA, USA
| | - Maria Boulina
- Diabetes Research Institute, University of Miami, Miami, FL, USA
| | - Madina Makhmutova
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Elizabeth Pereira
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, USA; Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Joana Almaça
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, USA; Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA; Molecular and Cellular Pharmacology Graduate Program, University of Miami Miller School of Medicine, Miami, FL, USA.
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24
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Grandi E, Navedo MF, Saucerman JJ, Bers DM, Chiamvimonvat N, Dixon RE, Dobrev D, Gomez AM, Harraz OF, Hegyi B, Jones DK, Krogh-Madsen T, Murfee WL, Nystoriak MA, Posnack NG, Ripplinger CM, Veeraraghavan R, Weinberg S. Diversity of cells and signals in the cardiovascular system. J Physiol 2023; 601:2547-2592. [PMID: 36744541 PMCID: PMC10313794 DOI: 10.1113/jp284011] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 01/19/2023] [Indexed: 02/07/2023] Open
Abstract
This white paper is the outcome of the seventh UC Davis Cardiovascular Research Symposium on Systems Approach to Understanding Cardiovascular Disease and Arrhythmia. This biannual meeting aims to bring together leading experts in subfields of cardiovascular biomedicine to focus on topics of importance to the field. The theme of the 2022 Symposium was 'Cell Diversity in the Cardiovascular System, cell-autonomous and cell-cell signalling'. Experts in the field contributed their experimental and mathematical modelling perspectives and discussed emerging questions, controversies, and challenges in examining cell and signal diversity, co-ordination and interrelationships involved in cardiovascular function. This paper originates from the topics of formal presentations and informal discussions from the Symposium, which aimed to develop a holistic view of how the multiple cell types in the cardiovascular system integrate to influence cardiovascular function, disease progression and therapeutic strategies. The first section describes the major cell types (e.g. cardiomyocytes, vascular smooth muscle and endothelial cells, fibroblasts, neurons, immune cells, etc.) and the signals involved in cardiovascular function. The second section emphasizes the complexity at the subcellular, cellular and system levels in the context of cardiovascular development, ageing and disease. Finally, the third section surveys the technological innovations that allow the interrogation of this diversity and advancing our understanding of the integrated cardiovascular function and dysfunction.
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Affiliation(s)
- Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Manuel F. Navedo
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Jeffrey J. Saucerman
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Donald M. Bers
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Nipavan Chiamvimonvat
- Department of Pharmacology, University of California Davis, Davis, CA, USA
- Department of Internal Medicine, University of California Davis, Davis, CA, USA
| | - Rose E. Dixon
- Department of Physiology and Membrane Biology, University of California Davis, Davis, CA, USA
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany
- Department of Medicine, Montreal Heart Institute and Université de Montréal, Montréal, Canada
- Department of Molecular Physiology & Biophysics, Baylor College of Medicine, Houston, TX, USA
| | - Ana M. Gomez
- Signaling and Cardiovascular Pathophysiology-UMR-S 1180, INSERM, Université Paris-Saclay, Orsay, France
| | - Osama F. Harraz
- Department of Pharmacology, Larner College of Medicine, and Vermont Center for Cardiovascular and Brain Health, University of Vermont, Burlington, VT, USA
| | - Bence Hegyi
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - David K. Jones
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, USA
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Trine Krogh-Madsen
- Department of Physiology & Biophysics, Weill Cornell Medicine, New York, New York, USA
| | - Walter Lee Murfee
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA
| | - Matthew A. Nystoriak
- Department of Medicine, Division of Environmental Medicine, Center for Cardiometabolic Science, University of Louisville, Louisville, KY, 40202, USA
| | - Nikki G. Posnack
- Department of Pediatrics, Department of Pharmacology and Physiology, The George Washington University, Washington, DC, USA
- Sheikh Zayed Institute for Pediatric and Surgical Innovation, Children’s National Heart Institute, Children’s National Hospital, Washington, DC, USA
| | | | - Rengasayee Veeraraghavan
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA
- Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University – Wexner Medical Center, Columbus, OH, USA
| | - Seth Weinberg
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA
- Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University – Wexner Medical Center, Columbus, OH, USA
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25
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Korte N, James G, You H, Hirunpattarasilp C, Christie I, Sethi H, Attwell D. Noradrenaline released from locus coeruleus axons contracts cerebral capillary pericytes via α2 adrenergic receptors. J Cereb Blood Flow Metab 2023; 43:1142-1152. [PMID: 36688515 PMCID: PMC10291462 DOI: 10.1177/0271678x231152549] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 11/15/2022] [Accepted: 01/03/2023] [Indexed: 01/24/2023]
Abstract
Noradrenaline (NA) release from locus coeruleus axons generates vascular contractile tone in arteriolar smooth muscle and contractile capillary pericytes. This tone allows neuronal activity to evoke vasodilation that increases local cerebral blood flow (CBF). Much of the vascular resistance within the brain is located in capillaries and locus coeruleus axons have NA release sites closer to pericytes than to arterioles. In acute brain slices, NA contracted pericytes but did not raise the pericyte cytoplasmic Ca2+ concentration, while the α1 agonist phenylephrine did not evoke contraction. Blocking α2 adrenergic receptors (α2Rs, which induce contraction by inhibiting cAMP production), greatly reduced the NA-evoked pericyte contraction, whereas stimulating α2Rs using xylazine (a sedative) or clonidine (an anti-hypertensive drug) evoked pericyte contraction. Noradrenaline-evoked pericyte contraction and capillary constriction are thus mediated via α2Rs. Consequently, α2Rs may not only modulate CBF in health and pathological conditions, but also contribute to CBF changes evoked by α2R ligands administered in research, veterinary and clinical settings.
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Affiliation(s)
- Nils Korte
- Dept of Neuroscience, Physiology & Pharmacology, University College London, London, UK
| | - Greg James
- Dept of Neuroscience, Physiology & Pharmacology, University College London, London, UK
- Department of Neurosurgery, Great Ormond Street Hospital, London, UK
| | - Haoming You
- Dept of Neuroscience, Physiology & Pharmacology, University College London, London, UK
| | - Chanawee Hirunpattarasilp
- Dept of Neuroscience, Physiology & Pharmacology, University College London, London, UK
- Princess Srisavangavadhana College of Medicine, Chulabhorn Royal Academy, Bangkok, Thailand
| | - Isabel Christie
- Dept of Neuroscience, Physiology & Pharmacology, University College London, London, UK
| | - Huma Sethi
- Dept of Neurosurgery, National Hospital for Neurology and Neurosurgery, London, UK
| | - David Attwell
- Dept of Neuroscience, Physiology & Pharmacology, University College London, London, UK
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26
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Staehr C, Giblin JT, Gutiérrez‐Jiménez E, Guldbrandsen HØ, Tang J, Sandow SL, Boas DA, Matchkov VV. Neurovascular Uncoupling Is Linked to Microcirculatory Dysfunction in Regions Outside the Ischemic Core Following Ischemic Stroke. J Am Heart Assoc 2023; 12:e029527. [PMID: 37232244 PMCID: PMC10381981 DOI: 10.1161/jaha.123.029527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 04/19/2023] [Indexed: 05/27/2023]
Abstract
Background Normal brain function depends on the ability of the vasculature to increase blood flow to regions with high metabolic demands. Impaired neurovascular coupling, such as the local hyperemic response to neuronal activity, may contribute to poor neurological outcome after stroke despite successful recanalization, that is, futile recanalization. Methods and Results Mice implanted with chronic cranial windows were trained for awake head-fixation before experiments. One-hour occlusion of the anterior middle cerebral artery branch was induced using single-vessel photothrombosis. Cerebral perfusion and neurovascular coupling were assessed by optical coherence tomography and laser speckle contrast imaging. Capillaries and pericytes were studied in perfusion-fixed tissue by labeling lectin and platelet-derived growth factor receptor β. Arterial occlusion induced multiple spreading depolarizations over 1 hour associated with substantially reduced blood flow in the peri-ischemic cortex. Approximately half of the capillaries in the peri-ischemic area were no longer perfused at the 3- and 24-hour follow-up (45% [95% CI, 33%-58%] and 53% [95% CI, 39%-66%] reduction, respectively; P<0.0001), which was associated with contraction of an equivalent proportion of peri-ischemic capillary pericytes. The capillaries in the peri-ischemic cortex that remained perfused showed increased point prevalence of dynamic flow stalling (0.5% [95% CI, 0.2%-0.7%] at baseline, 5.1% [95% CI, 3.2%-6.5%] and 3.2% [95% CI, 1.1%-5.3%] at 3- and 24-hour follow-up, respectively; P=0.001). Whisker stimulation at the 3- and 24-hour follow-up led to reduced neurovascular coupling responses in the sensory cortex corresponding to the peri-ischemic region compared with that observed at baseline. Conclusions Arterial occlusion led to contraction of capillary pericytes and capillary flow stalling in the peri-ischemic cortex. Capillary dysfunction was associated with neurovascular uncoupling. Neurovascular coupling impairment associated with capillary dysfunction may be a mechanism that contributes to futile recanalization. Hence, the results from this study suggest a novel treatment target to improve neurological outcome after stroke.
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Affiliation(s)
- Christian Staehr
- Department of BiomedicineAarhus UniversityAarhusDenmark
- Neurophotonics Center, Department of Biomedical EngineeringBoston UniversityBostonMAUSA
| | - John T. Giblin
- Neurophotonics Center, Department of Biomedical EngineeringBoston UniversityBostonMAUSA
| | - Eugenio Gutiérrez‐Jiménez
- Center of Functionally Integrative Neuroscience, Institute for Clinical MedicineAarhus UniversityAarhusDenmark
| | | | - Jianbo Tang
- Neurophotonics Center, Department of Biomedical EngineeringBoston UniversityBostonMAUSA
- Department of Biomedical EngineeringSouthern University of Science and TechnologyShenzhenChina
| | - Shaun L. Sandow
- Biomedical Science, School of HealthUniversity of the Sunshine CoastSippy DownsAustralia
- Centre for Clinical Research, Faculty of MedicineThe University of QueenslandBrisbaneAustralia
| | - David A. Boas
- Neurophotonics Center, Department of Biomedical EngineeringBoston UniversityBostonMAUSA
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27
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Quijada P, Park S, Zhao P, Kolluri KS, Wong D, Shih KD, Fang K, Pezhouman A, Wang L, Daraei A, Tran MD, Rathbun EM, Burgos Villar KN, Garcia-Hernandez ML, Pham TT, Lowenstein CJ, Iruela-Arispe ML, Carmichael ST, Small EM, Ardehali R. Cardiac pericytes mediate the remodeling response to myocardial infarction. J Clin Invest 2023; 133:e162188. [PMID: 37183820 PMCID: PMC10178847 DOI: 10.1172/jci162188] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 03/28/2023] [Indexed: 05/16/2023] Open
Abstract
Despite the prevalence of pericytes in the microvasculature of the heart, their role during ischemia-induced remodeling remains unclear. We used multiple lineage-tracing mouse models and found that pericytes migrated to the injury site and expressed profibrotic genes, coinciding with increased vessel leakage after myocardial infarction (MI). Single-cell RNA-Seq of cardiac pericytes at various time points after MI revealed the temporally regulated induction of genes related to vascular permeability, extracellular matrix production, basement membrane degradation, and TGF-β signaling. Deleting TGF-β receptor 1 in chondroitin sulfate proteoglycan 4-expressing (Cspg4-expressing) cells reduced fibrosis following MI, leading to a transient improvement in the cardiac ejection fraction. Furthermore, genetic ablation of Cspg4-expressing cells resulted in excessive vascular permeability, a decline in cardiac function, and increased mortality in the second week after MI. These data reveal an essential role for cardiac pericytes in the control of vascular homeostasis and the fibrotic response after acute ischemic injury, information that will help guide the development of novel strategies to preserve vascular integrity and attenuate pathological cardiac remodeling.
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Affiliation(s)
- Pearl Quijada
- Department of Integrative Biology and Physiology
- Eli and Edythe Broad Stem Research Center
- Molecular Biology Institute
- Molecular, Cellular, and Integrative Physiology Graduate Program, and
| | - Shuin Park
- Molecular, Cellular, and Integrative Physiology Graduate Program, and
- Cardiology, Internal Medicine, David Geffen School of Medicine, UCLA, Los Angeles, California, USA
| | - Peng Zhao
- Eli and Edythe Broad Stem Research Center
- Cardiology, Internal Medicine, David Geffen School of Medicine, UCLA, Los Angeles, California, USA
| | - Kamal S.S. Kolluri
- Cardiology, Internal Medicine, David Geffen School of Medicine, UCLA, Los Angeles, California, USA
| | - David Wong
- Department of Integrative Biology and Physiology
- Molecular, Cellular, and Integrative Physiology Graduate Program, and
| | | | - Kai Fang
- Cardiology, Internal Medicine, David Geffen School of Medicine, UCLA, Los Angeles, California, USA
| | - Arash Pezhouman
- Section of Cardiology, Department of Internal Medicine, Baylor College of Medicine, Houston, Texas, USA
- The Texas Heart Institute, Houston, Texas, USA
| | - Lingjun Wang
- Cardiology, Internal Medicine, David Geffen School of Medicine, UCLA, Los Angeles, California, USA
- Cardiology, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Ali Daraei
- Cardiology, Internal Medicine, David Geffen School of Medicine, UCLA, Los Angeles, California, USA
| | | | - Elle M. Rathbun
- Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, California, USA
| | - Kimberly N. Burgos Villar
- Department of Pathology
- Department of Medicine, Aab Cardiovascular Research Institute, School of Medicine and Dentistry, and
| | | | - Thanh T.D. Pham
- Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, California, USA
| | - Charles J. Lowenstein
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Maryland, USA
| | - M. Luisa Iruela-Arispe
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - S. Thomas Carmichael
- Eli and Edythe Broad Stem Research Center
- Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, California, USA
| | - Eric M. Small
- Department of Medicine, Aab Cardiovascular Research Institute, School of Medicine and Dentistry, and
- Department of Pharmacology and Physiology and
- Department of Biomedical Engineering, University of Rochester, Rochester, New York, USA
| | - Reza Ardehali
- Section of Cardiology, Department of Internal Medicine, Baylor College of Medicine, Houston, Texas, USA
- The Texas Heart Institute, Houston, Texas, USA
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28
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Phillips B, Clark J, Martineau É, Rungta RL. Orai, RyR, and IP 3R channels cooperatively regulate calcium signaling in brain mid-capillary pericytes. Commun Biol 2023; 6:493. [PMID: 37149720 PMCID: PMC10164186 DOI: 10.1038/s42003-023-04858-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 04/21/2023] [Indexed: 05/08/2023] Open
Abstract
Pericytes are multifunctional cells of the vasculature that are vital to brain homeostasis, yet many of their fundamental physiological properties, such as Ca2+ signaling pathways, remain unexplored. We performed pharmacological and ion substitution experiments to investigate the mechanisms underlying pericyte Ca2+ signaling in acute cortical brain slices of PDGFRβ-Cre::GCaMP6f mice. We report that mid-capillary pericyte Ca2+ signalling differs from ensheathing type pericytes in that it is largely independent of L- and T-type voltage-gated calcium channels. Instead, Ca2+ signals in mid-capillary pericytes were inhibited by multiple Orai channel blockers, which also inhibited Ca2+ entry triggered by endoplasmic reticulum (ER) store depletion. An investigation into store release pathways indicated that Ca2+ transients in mid-capillary pericytes occur through a combination of IP3R and RyR activation, and that Orai store-operated calcium entry (SOCE) is required to sustain and amplify intracellular Ca2+ increases evoked by the GqGPCR agonist endothelin-1. These results suggest that Ca2+ influx via Orai channels reciprocally regulates IP3R and RyR release pathways in the ER, which together generate spontaneous Ca2+ transients and amplify Gq-coupled Ca2+ elevations in mid-capillary pericytes. Thus, SOCE is a major regulator of pericyte Ca2+ and a target for manipulating their function in health and disease.
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Affiliation(s)
- Braxton Phillips
- Department of Neuroscience, Université de Montréal, Montréal, QC, Canada
- Department of Stomatology, Faculty of Dental Medicine, Université de Montréal, Montréal, QC, H3C3J7, Canada
- Centre interdisciplinaire de recherche sur le cerveau et l'apprentissage, Université de Montréal, Montréal, QC, Canada
| | - Jenna Clark
- Department of Neuroscience, Université de Montréal, Montréal, QC, Canada
- Department of Stomatology, Faculty of Dental Medicine, Université de Montréal, Montréal, QC, H3C3J7, Canada
- Centre interdisciplinaire de recherche sur le cerveau et l'apprentissage, Université de Montréal, Montréal, QC, Canada
| | - Éric Martineau
- Department of Stomatology, Faculty of Dental Medicine, Université de Montréal, Montréal, QC, H3C3J7, Canada
- Centre interdisciplinaire de recherche sur le cerveau et l'apprentissage, Université de Montréal, Montréal, QC, Canada
| | - Ravi L Rungta
- Department of Stomatology, Faculty of Dental Medicine, Université de Montréal, Montréal, QC, H3C3J7, Canada.
- Centre interdisciplinaire de recherche sur le cerveau et l'apprentissage, Université de Montréal, Montréal, QC, Canada.
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29
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Perrino BA, Malogan J, Cobine CA, Sasse KC. Mfge8 is expressed by pericytes in gastric antrum submucosa from patients with obesity. Am J Physiol Cell Physiol 2023; 324:C992-C1006. [PMID: 36939201 PMCID: PMC10110711 DOI: 10.1152/ajpcell.00043.2023] [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: 02/02/2023] [Revised: 03/07/2023] [Accepted: 03/08/2023] [Indexed: 03/21/2023]
Abstract
The main function of the stomach is to digest ingested food. Gastric antrum muscular contractions mix ingested food with digestive enzymes and stomach acid and propel the chyme through the pyloric sphincter at a rate in which the small intestine can process the chyme for optimal nutrient absorption. Mfge8 binding to α8β1 integrins helps regulate gastric emptying by reducing the force of antral smooth muscle contractions. The source of Mfge8 within gastric muscles is unclear. Since Mfge8 is a secreted protein, Mfge8 could be delivered via the circulation, or be locally secreted by cells within the muscle layers. In this study, we identify a source of Mfge8 within human gastric antrum muscles using spatial transcriptomic analysis. We show that Mfge8 is expressed in subpopulations of Mef2c+ perivascular cells within the submucosa layer of the gastric antrum. Mef2c is expressed in subpopulations of NG2+ and PDGFRB+ pericytes. Mfge8 is expressed in NG2+/Mef2c+ pericytes, but not in NG2+/Mef2c-, PDGFRB+/Mef2c-, or PDGFRB+/Mef2c+ pericytes. Mfge8 is absent from CD34+ endothelial cells but is expressed in a small population of perivascular ACTA2+ cells. We also show that α8 integrin is not expressed by interstitial cells of Cajal (ICC), supporting the findings that Mfge8 attenuates gastric antrum smooth muscle contractions by binding to α8β1 integrins on enteric smooth muscle cells. These findings suggest a novel, supplementary mechanism of regulation of gastric antrum motility by cellular regulators of capillary blood flow, in addition to the regulation of gastric antrum motility by the enteric nervous system and the SMC, ICC, and PDGFRα+ cell (SIP) syncytium.
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Affiliation(s)
- Brian A Perrino
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada, United States
| | - Justin Malogan
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada, United States
| | - Caroline A Cobine
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada, United States
| | - Kent C Sasse
- Nevada Surgical Associates, Reno, Nevada, United States
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Sargent SM, Bonney SK, Li Y, Stamenkovic S, Takeno M, Coelho-Santos V, Shih AY. Endothelial structure contributes to heterogeneity in brain capillary diameter. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.26.538503. [PMID: 37163126 PMCID: PMC10168366 DOI: 10.1101/2023.04.26.538503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The high metabolic demand of brain tissue is supported by a constant supply of blood through dense microvascular networks. Capillaries are the smallest class of vessels and vary in diameter between ∼2 to 5 μm in the brain. This diameter range plays a significant role in the optimization of blood flow resistance, blood cell distribution, and oxygen extraction. The control of capillary diameter has largely been ascribed to pericyte contractility, but it remains unclear if endothelial wall architecture also contributes to capillary diameter heterogeneity. Here, we use public, large-scale volume electron microscopy data from mouse cortex (MICrONS Explorer, Cortical MM^3) to examine how endothelial cell number, endothelial cell thickness, and pericyte coverage relates to microvascular lumen size. We find that transitional vessels near the penetrating arteriole and ascending venule are composed of 2 to 5 interlocked endothelial cells, while the numerous capillary segments intervening these zones are composed of either 1 or 2 endothelial cells, with roughly equal proportions. The luminal area and diameter is on average slightly larger with capillary segments composed of 2 interlocked endothelial cells versus 1 endothelial cell. However, this difference is insufficient to explain the full range of capillary diameters seen in vivo. This suggests that both endothelial structure and other influences, such as pericyte tone, contribute to the basal diameter and optimized perfusion of brain capillaries.
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31
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Eisenmenger LB, Peret A, Famakin BM, Spahic A, Roberts GS, Bockholt JH, Johnson KM, Paulsen JS. Vascular contributions to Alzheimer's disease. Transl Res 2023; 254:41-53. [PMID: 36529160 PMCID: PMC10481451 DOI: 10.1016/j.trsl.2022.12.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 12/05/2022] [Accepted: 12/12/2022] [Indexed: 12/23/2022]
Abstract
Alzheimer's disease (AD) is the most common cause of dementia and is characterized by progressive neurodegeneration and cognitive decline. Understanding the pathophysiology underlying AD is paramount for the management of individuals at risk of and suffering from AD. The vascular hypothesis stipulates a relationship between cardiovascular disease and AD-related changes although the nature of this relationship remains unknown. In this review, we discuss several potential pathological pathways of vascular involvement in AD that have been described including dysregulation of neurovascular coupling, disruption of the blood brain barrier, and reduced clearance of metabolite waste such as beta-amyloid, a toxic peptide considered the hallmark of AD. We will also discuss the two-hit hypothesis which proposes a 2-step positive feedback loop in which microvascular insults precede the accumulation of Aß and are thought to be at the origin of the disease development. At neuroimaging, signs of vascular dysfunction such as chronic cerebral hypoperfusion have been demonstrated, appearing early in AD, even before cognitive decline and alteration of traditional biomarkers. Cerebral small vessel disease such as cerebral amyloid angiopathy, characterized by the aggregation of Aß in the vessel wall, is highly prevalent in vascular dementia and AD patients. Current data is unclear whether cardiovascular disease causes, precipitates, amplifies, precedes, or simply coincides with AD. Targeted imaging tools to quantitatively evaluate the intracranial vasculature and longitudinal studies in individuals at risk for or in the early stages of the AD continuum could be critical in disentangling this complex relationship between vascular disease and AD.
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Affiliation(s)
- Laura B Eisenmenger
- Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Anthony Peret
- Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Bolanle M Famakin
- Department of Neurology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Alma Spahic
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin
| | - Grant S Roberts
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin
| | - Jeremy H Bockholt
- Tri-Institutional Center for Translational Research in Neuroimaging and Data Science (TReNDS), Georgia State University, Georgia Institute of Technology, and Emory University, Atlanta, Georgia
| | - Kevin M Johnson
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin
| | - Jane S Paulsen
- Department of Neurology, University of Wisconsin-Madison, Madison, Wisconsin.
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Dion-Albert L, Dudek KA, Russo SJ, Campbell M, Menard C. Neurovascular adaptations modulating cognition, mood, and stress responses. Trends Neurosci 2023; 46:276-292. [PMID: 36805768 DOI: 10.1016/j.tins.2023.01.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 01/11/2023] [Accepted: 01/25/2023] [Indexed: 02/19/2023]
Abstract
The neurovascular unit (NVU) is a dynamic center for substance exchange between the blood and the brain, making it an essential gatekeeper for central nervous system (CNS) homeostasis. Recent evidence supports a role for the NVU in modulating brain function and cognition. In addition, alterations in NVU processes are observed in response to stress, although the mechanisms via which they can affect mood and cognitive functions remain elusive. Here, we summarize recent studies of neurovascular regulation of emotional processes and cognitive function, including under stressful conditions. We also highlight relevant RNA-sequencing (RNA-seq) databases aiming to profile the NVU along with innovative tools to study and manipulate NVU function that can be exploited in the context of cognition and stress research throughout development, aging, or brain disorders.
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Affiliation(s)
- Laurence Dion-Albert
- Department of Psychiatry and Neuroscience, Faculty of Medicine and CERVO Brain Research Center, Université Laval, Quebec City, QC, Canada
| | - Katarzyna A Dudek
- Department of Psychiatry and Neuroscience, Faculty of Medicine and CERVO Brain Research Center, Université Laval, Quebec City, QC, Canada
| | - Scott J Russo
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai and Center for Affective Neuroscience, 1 Gustave L Levy Place, New York, NY, USA
| | - Matthew Campbell
- Smurfit Institute of Genetics, Trinity College Dublin, Lincoln Place Gate, Dublin 2, Ireland
| | - Caroline Menard
- Department of Psychiatry and Neuroscience, Faculty of Medicine and CERVO Brain Research Center, Université Laval, Quebec City, QC, Canada.
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The Active Role of Pericytes During Neuroinflammation in the Adult Brain. Cell Mol Neurobiol 2023; 43:525-541. [PMID: 35195811 DOI: 10.1007/s10571-022-01208-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 02/13/2022] [Indexed: 12/11/2022]
Abstract
Microvessels in the central nervous system (CNS) have one of the highest populations of pericytes, indicating their crucial role in maintaining homeostasis. Pericytes are heterogeneous cells located around brain microvessels; they present three different morphologies along the CNS vascular tree: ensheathing, mesh, and thin-strand pericytes. At the arteriole-capillary transition ensheathing pericytes are found, while mesh and thin-strand pericytes are located at capillary beds. Brain pericytes are essential for the establishment and maintenance of the blood-brain barrier, which restricts the passage of soluble and potentially toxic molecules from the circulatory system to the brain parenchyma. Pericytes play a key role in regulating local inflammation at the CNS. Pericytes can respond differentially, depending on the degree of inflammation, by secreting a set of neurotrophic factors to promote cell survival and regeneration, or by potentiating inflammation through the release of inflammatory mediators (e.g., cytokines and chemokines), and the overexpression of cell adhesion molecules. Under inflammatory conditions, pericytes may regulate immune cell trafficking to the CNS and play a role in perpetuating local inflammation. In this review, we describe pericyte responses during acute and chronic neuroinflammation.
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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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Harris WJ, Asselin MC, Hinz R, Parkes LM, Allan S, Schiessl I, Boutin H, Dickie BR. In vivo methods for imaging blood-brain barrier function and dysfunction. Eur J Nucl Med Mol Imaging 2023; 50:1051-1083. [PMID: 36437425 PMCID: PMC9931809 DOI: 10.1007/s00259-022-05997-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 10/09/2022] [Indexed: 11/29/2022]
Abstract
The blood-brain barrier (BBB) is the interface between the central nervous system and systemic circulation. It tightly regulates what enters and is removed from the brain parenchyma and is fundamental in maintaining brain homeostasis. Increasingly, the BBB is recognised as having a significant role in numerous neurological disorders, ranging from acute disorders (traumatic brain injury, stroke, seizures) to chronic neurodegeneration (Alzheimer's disease, vascular dementia, small vessel disease). Numerous approaches have been developed to study the BBB in vitro, in vivo, and ex vivo. The complex multicellular structure and effects of disease are difficult to recreate accurately in vitro, and functional aspects of the BBB cannot be easily studied ex vivo. As such, the value of in vivo methods to study the intact BBB cannot be overstated. This review discusses the structure and function of the BBB and how these are affected in diseases. It then discusses in depth several established and novel methods for imaging the BBB in vivo, with a focus on MRI, nuclear imaging, and high-resolution intravital fluorescence microscopy.
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Affiliation(s)
- William James Harris
- Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Northern Care Alliance & University of Manchester, Manchester, UK
- Division of Neuroscience, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, M13 9PL, Manchester, UK
| | - Marie-Claude Asselin
- Division of Informatics, Imaging and Data Sciences, School of Health Sciences, University of Manchester, Manchester, UK
| | - Rainer Hinz
- Wolfson Molecular Imaging Centre, University of Manchester, Manchester, UK
| | - Laura Michelle Parkes
- Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Northern Care Alliance & University of Manchester, Manchester, UK
- Division of Neuroscience, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, M13 9PL, Manchester, UK
| | - Stuart Allan
- Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Northern Care Alliance & University of Manchester, Manchester, UK
- Division of Neuroscience, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, M13 9PL, Manchester, UK
| | - Ingo Schiessl
- Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Northern Care Alliance & University of Manchester, Manchester, UK
- Division of Neuroscience, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, M13 9PL, Manchester, UK
| | - Herve Boutin
- Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Northern Care Alliance & University of Manchester, Manchester, UK.
- Division of Neuroscience, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, M13 9PL, Manchester, UK.
- Wolfson Molecular Imaging Centre, University of Manchester, Manchester, UK.
| | - Ben Robert Dickie
- Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Northern Care Alliance & University of Manchester, Manchester, UK
- Division of Informatics, Imaging and Data Sciences, School of Health Sciences, University of Manchester, Manchester, UK
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Cashion JM, Young KM, Sutherland BA. How does neurovascular unit dysfunction contribute to multiple sclerosis? Neurobiol Dis 2023; 178:106028. [PMID: 36736923 DOI: 10.1016/j.nbd.2023.106028] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 01/17/2023] [Accepted: 01/30/2023] [Indexed: 02/04/2023] Open
Abstract
Multiple sclerosis is an inflammatory demyelinating disease of the central nervous system (CNS) and the most common non-traumatic cause of neurological disability in young adults. Multiple sclerosis clinical care has improved considerably due to the development of disease-modifying therapies that effectively modulate the peripheral immune response and reduce relapse frequency. However, current treatments do not prevent neurodegeneration and disease progression, and efforts to prevent multiple sclerosis will be hampered so long as the cause of this disease remains unknown. Risk factors for multiple sclerosis development or severity include vitamin D deficiency, cigarette smoking and youth obesity, which also impact vascular health. People with multiple sclerosis frequently experience blood-brain barrier breakdown, microbleeds, reduced cerebral blood flow and diminished neurovascular reactivity, and it is possible that these vascular pathologies are tied to multiple sclerosis development. The neurovascular unit is a cellular network that controls neuroinflammation, maintains blood-brain barrier integrity, and tightly regulates cerebral blood flow, matching energy supply to neuronal demand. The neurovascular unit is composed of vessel-associated cells such as endothelial cells, pericytes and astrocytes, however neuronal and other glial cell types also comprise the neurovascular niche. Recent single-cell transcriptomics data, indicate that neurovascular cells, particular cells of the microvasculature, are compromised within multiple sclerosis lesions. Large-scale genetic and small-scale cell biology studies also suggest that neurovascular dysfunction could be a primary pathology contributing to multiple sclerosis development. Herein we revisit multiple sclerosis risk factors and multiple sclerosis pathophysiology and highlight the known and potential roles of neurovascular unit dysfunction in multiple sclerosis development and disease progression. We also evaluate the suitability of the neurovascular unit as a potential target for future disease modifying therapies for multiple sclerosis.
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Affiliation(s)
- Jake M Cashion
- Tasmanian School of Medicine, College of Health and Medicine, University of Tasmania, Hobart, Tasmania, Australia
| | - Kaylene M Young
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania 7000, Australia
| | - Brad A Sutherland
- Tasmanian School of Medicine, College of Health and Medicine, University of Tasmania, Hobart, Tasmania, Australia.
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Klug NR, Sancho M, Gonzales AL, Heppner TJ, O’Brien RIC, Hill-Eubanks D, Nelson MT. Intraluminal pressure elevates intracellular calcium and contracts CNS pericytes: Role of voltage-dependent calcium channels. Proc Natl Acad Sci U S A 2023; 120:e2216421120. [PMID: 36802432 PMCID: PMC9992766 DOI: 10.1073/pnas.2216421120] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 01/24/2023] [Indexed: 02/23/2023] Open
Abstract
Arteriolar smooth muscle cells (SMCs) and capillary pericytes dynamically regulate blood flow in the central nervous system in the face of fluctuating perfusion pressures. Pressure-induced depolarization and Ca2+ elevation provide a mechanism for regulation of SMC contraction, but whether pericytes participate in pressure-induced changes in blood flow remains unknown. Here, utilizing a pressurized whole-retina preparation, we found that increases in intraluminal pressure in the physiological range induce contraction of both dynamically contractile pericytes in the arteriole-proximate transition zone and distal pericytes of the capillary bed. We found that the contractile response to pressure elevation was slower in distal pericytes than in transition zone pericytes and arteriolar SMCs. Pressure-evoked elevation of cytosolic Ca2+ and contractile responses in SMCs were dependent on voltage-dependent Ca2+ channel (VDCC) activity. In contrast, Ca2+ elevation and contractile responses were partially dependent on VDCC activity in transition zone pericytes and independent of VDCC activity in distal pericytes. In both transition zone and distal pericytes, membrane potential at low inlet pressure (20 mmHg) was approximately -40 mV and was depolarized to approximately -30 mV by an increase in pressure to 80 mmHg. The magnitude of whole-cell VDCC currents in freshly isolated pericytes was approximately half that measured in isolated SMCs. Collectively, these results indicate a loss of VDCC involvement in pressure-induced constriction along the arteriole-capillary continuum. They further suggest that alternative mechanisms and kinetics of Ca2+ elevation, contractility, and blood flow regulation exist in central nervous system capillary networks, distinguishing them from neighboring arterioles.
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Affiliation(s)
- Nicholas R. Klug
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT05405
| | - Maria Sancho
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT05405
| | - Albert L. Gonzales
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT05405
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, NV89557
| | - Thomas J. Heppner
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT05405
| | | | - David Hill-Eubanks
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT05405
| | - Mark T. Nelson
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT05405
- Division of Cardiovascular Sciences, University of Manchester, ManchesterM13 9PL, UK
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Nuñez-Diaz C, Pocevičiūtė D, Schultz N, Welinder C, Swärd K, Wennström M. Contraction of human brain vascular pericytes in response to islet amyloid polypeptide is reversed by pramlintide. Mol Brain 2023; 16:25. [PMID: 36793056 PMCID: PMC9933335 DOI: 10.1186/s13041-023-01013-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 02/05/2023] [Indexed: 02/17/2023] Open
Abstract
The islet amyloid polypeptide (IAPP), a pancreas-produced peptide, has beneficial functions in its monomeric form. However, IAPP aggregates, related to type 2 diabetes mellitus (T2DM), are toxic not only for the pancreas, but also for the brain. In the latter, IAPP is often found in vessels, where it is highly toxic for pericytes, mural cells that have contractile properties and regulate capillary blood flow. In the current study, we use a microvasculature model, where human brain vascular pericytes (HBVP) are co-cultured together with human cerebral microvascular endothelial cells, to demonstrate that IAPP oligomers (oIAPP) alter the morphology and contractility of HBVP. Contraction and relaxation of HBVP was verified using the vasoconstrictor sphingosine-1-phosphate (S1P) and vasodilator Y27632, where the former increased, and the latter decreased, the number of HBVP with round morphology. Increased number of round HBVP was also seen after oIAPP stimulation, and the effect was reverted by the IAPP analogue pramlintide, Y27632, and the myosin inhibitor blebbistatin. Inhibition of the IAPP receptor with the antagonist AC187 only reverted IAPP effects partially. Finally, we demonstrate by immunostaining of human brain tissue against laminin that individuals with high amount of brain IAPP levels show significantly lower capillary diameter and altered mural cell morphology compared to individuals with low brain IAPP levels. These results indicate that HBVP, in an in vitro model of microvasculature, respond morphologically to vasoconstrictors, dilators, and myosin inhibitors. They also suggest that oIAPP induces contraction of these mural cells and that pramlintide can reverse such contraction.
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Affiliation(s)
- Cristina Nuñez-Diaz
- grid.4514.40000 0001 0930 2361Cognitive Disorder Research Unit, Department of Clinical Sciences Malmö, Lund University, Malmö, Sweden
| | - Dovilė Pocevičiūtė
- grid.4514.40000 0001 0930 2361Cognitive Disorder Research Unit, Department of Clinical Sciences Malmö, Lund University, Malmö, Sweden
| | - Nina Schultz
- grid.4514.40000 0001 0930 2361Cognitive Disorder Research Unit, Department of Clinical Sciences Malmö, Lund University, Malmö, Sweden
| | - The Netherlands Brain Bank
- grid.419918.c0000 0001 2171 8263Netherlands Institute for Neuroscience, Meibergdreef 47, 1105 BA Amsterdam, The Netherlands
| | - Charlotte Welinder
- grid.4514.40000 0001 0930 2361Faculty of Medicine, Department of Clinical Sciences, Lund, Mass Spectrometry, Lund University, Lund, Sweden
| | - Karl Swärd
- grid.4514.40000 0001 0930 2361Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Malin Wennström
- Cognitive Disorder Research Unit, Department of Clinical Sciences Malmö, Lund University, Malmö, Sweden.
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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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Mechanisms of the "No-Reflow" Phenomenon After Acute Myocardial Infarction: Potential Role of Pericytes. JACC Basic Transl Sci 2023; 8:204-220. [PMID: 36908667 PMCID: PMC9998747 DOI: 10.1016/j.jacbts.2022.06.008] [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] [Received: 05/20/2022] [Revised: 06/13/2022] [Accepted: 06/13/2022] [Indexed: 11/20/2022]
Abstract
Pericytes contract during myocardial ischemia resulting in capillary constriction and no reflow. Reversing pericyte contraction pharmacologically reduces no reflow and infarct size. These findings open up an entire new venue of research aimed at altering pericyte function in myocardial ischemia and infarction.
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Murdock MH, Tsai LH. Insights into Alzheimer's disease from single-cell genomic approaches. Nat Neurosci 2023; 26:181-195. [PMID: 36593328 PMCID: PMC10155598 DOI: 10.1038/s41593-022-01222-2] [Citation(s) in RCA: 40] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 10/28/2022] [Indexed: 01/03/2023]
Abstract
Alzheimer's disease (AD) is an age-related disease pathologically defined by the deposition of amyloid plaques and neurofibrillary tangles in the brain parenchyma. Single-cell profiling has shown that Alzheimer's dementia involves the complex interplay of virtually every major brain cell type. Here, we highlight cell-type-specific molecular perturbations in AD. We discuss how genomic information from single cells expands existing paradigms of AD pathogenesis and highlight new opportunities for therapeutic interventions.
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Affiliation(s)
- Mitchell H Murdock
- Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Li-Huei Tsai
- Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA, USA.
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Hakim MA, Behringer EJ. K IR channel regulation of electrical conduction along cerebrovascular endothelium: Enhanced modulation during Alzheimer's disease. Microcirculation 2023; 30:e12797. [PMID: 36577656 PMCID: PMC9885900 DOI: 10.1111/micc.12797] [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: 07/15/2022] [Revised: 11/22/2022] [Accepted: 12/22/2022] [Indexed: 12/29/2022]
Abstract
OBJECTIVE Endothelial cell (EC) coupling occurs through gap junctions and underlies cerebral blood flow regulation governed by inward-rectifying K+ (KIR ) channels. This study addressed effects of KIR channel activity on EC coupling before and during Alzheimer's disease (AD). METHODS Intact EC tubes (width: ~90-100 μm; length: ~0.5 mm) were freshly isolated from posterior cerebral arteries of young Pre-AD (1-3 months) and aged AD (13-18 months) male and female 3xTg-AD mice. Dual intracellular microelectrodes applied simultaneous current injections (±0.5-3 nA) and membrane potential (Vm ) recordings in ECs at distance ~400 μm. Elevated extracellular potassium ([K+ ]E ; 8-15 mmol/L; reference, 5 mmol/L) activated KIR channels. RESULTS Conducted Vm (∆Vm ) responses ranged from ~-30 to 30 mV in response to -3 to +3 nA (linear regression, R2 ≥ .99) while lacking rectification for charge polarity or axial direction of spread. Conduction slope decreased ~10%-20% during 15 mmol/L [K+ ]E in Pre-AD males and AD females. 15 mmol/L [K+ ]E decreased conduction by ~10%-20% at lower ∆Vm thresholds in AD animals (~±20 mV) versus Pre-AD (~±25 mV). AD increased conducted hyperpolarization by ~10%-15% during 8-12 mmol/L [K+ ]E . CONCLUSIONS Brain endothelial KIR channel activity modulates bidirectional spread of vasoreactive signals with enhanced regulation of EC coupling during AD pathology.
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Affiliation(s)
- Md A. Hakim
- Basic Sciences, Loma Linda University, Loma Linda, CA 92350, USA
| | - Erik J. Behringer
- Basic Sciences, Loma Linda University, Loma Linda, CA 92350, USA,Corresponding Author: Erik J. Behringer, Ph.D., Department of Basic Sciences, 11041 Campus Street, Risley Hall, Loma Linda University, Loma Linda, CA 92350, , tel: (909) 651-5334, fax: (909) 558-0119
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Sargent SM, Bonney SK, Li Y, Stamenkovic S, Takeno MM, Coelho-Santos V, Shih AY. Endothelial structure contributes to heterogeneity in brain capillary diameter. VASCULAR BIOLOGY (BRISTOL, ENGLAND) 2023; 5:e230010. [PMID: 37582180 PMCID: PMC10503221 DOI: 10.1530/vb-23-0010] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Accepted: 08/15/2023] [Indexed: 08/17/2023]
Abstract
The high metabolic demand of brain tissue is supported by a constant supply of blood flow through dense microvascular networks. Capillaries are the smallest class of vessels in the brain and their lumens vary in diameter between ~2 and 5 μm. This diameter range plays a significant role in optimizing blood flow resistance, blood cell distribution, and oxygen extraction. The control of capillary diameter has largely been ascribed to pericyte contractility, but it remains unclear if the architecture of the endothelial wall also contributes to capillary diameter. Here, we use public, large-scale volume electron microscopy data from mouse cortex (MICrONS Explorer, Cortical mm3) to examine how endothelial cell number, endothelial cell thickness, and pericyte coverage relates to microvascular lumen size. We find that transitional vessels near the penetrating arteriole and ascending venule are composed of two to six interlocked endothelial cells, while the capillaries intervening these zones are composed of either one or two endothelial cells, with roughly equal proportions. The luminal area and diameter are on average slightly larger with capillary segments composed of two interlocked endothelial cells vs one endothelial cell. However, this difference is insufficient to explain the full range of capillary diameters seen in vivo. This suggests that both endothelial structure and other influences, including pericyte tone, contribute to the basal diameter and optimized perfusion of brain capillaries.
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Affiliation(s)
- Sheridan M Sargent
- Neuroscience Graduate Program, University of Washington, Seattle, Washington, USA
| | - Stephanie K Bonney
- Center for Developmental Biology and Regenerative Medicine, Seattle Children’s Research Institute, Seattle, Washington, USA
| | - Yuandong Li
- Center for Developmental Biology and Regenerative Medicine, Seattle Children’s Research Institute, Seattle, Washington, USA
| | - Stefan Stamenkovic
- Center for Developmental Biology and Regenerative Medicine, Seattle Children’s Research Institute, Seattle, Washington, USA
| | - Marc M Takeno
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Vanessa Coelho-Santos
- Coimbra Institute for Biomedical Imaging and Translational Research, University of Coimbra, Portugal
- Institute of Nuclear Sciences Applied to Health, University of Coimbra, Portugal
| | - Andy Y Shih
- Neuroscience Graduate Program, University of Washington, Seattle, Washington, USA
- Center for Developmental Biology and Regenerative Medicine, Seattle Children’s Research Institute, Seattle, Washington, USA
- Department of Pediatrics, University of Washington, Seattle, Washington, USA
- Department of Bioengineering, University of Washington, Seattle, Washington, USA
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44
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Grubb S. Ultrastructure of precapillary sphincters and the neurovascular unit. VASCULAR BIOLOGY (BRISTOL, ENGLAND) 2023; 5:e230011. [PMID: 37855433 PMCID: PMC10762554 DOI: 10.1530/vb-23-0011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 10/09/2023] [Indexed: 10/20/2023]
Abstract
Neurons communicate with vasculature to regulate blood flow in the brain, a process maintained by the neurovascular unit (NVU). This interaction, termed neurovascular coupling, is believed to involve astrocytes or molecules capable of traversing the astrocytic endfeet. The precise mechanism, however, remains elusive. Using large 3D electron microscopy datasets, we can now study the entire NVU in context of vascular hierarchy. This study presents evidence supporting the role of precapillary sphincters as a nexus for neurovascular coupling and endothelial transcytosis. It also highlights the role of fibroblast-synthesized collagen in fortifying first-order capillaries. Furthermore, I demonstrate how astrocytic endfeet establish a barrier for fluid flow and reveal that the cortex's microvasculature is semicircled by an unexpected arrangement of parenchymal neuronal processes around penetrating arterioles and arterial-end capillaries in both mouse and human brains. These discoveries offer insights into the NVU's structure and its operational mechanisms, potentially aiding researchers in devising new strategies for preserving cognitive function and promoting healthy aging.
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Affiliation(s)
- Søren Grubb
- Department of Neuroscience and Center for Translational Neuromedicine, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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45
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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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46
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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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47
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Abdelazim H, Payne LB, Nolan K, Paralkar K, Bradley V, Kanodia R, Gude R, Ward R, Monavarfeshani A, Fox MA, Chappell JC. Pericyte heterogeneity identified by 3D ultrastructural analysis of the microvessel wall. Front Physiol 2022; 13:1016382. [PMID: 36589416 PMCID: PMC9800988 DOI: 10.3389/fphys.2022.1016382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 12/05/2022] [Indexed: 12/23/2022] Open
Abstract
Confident identification of pericytes (PCs) remains an obstacle in the field, as a single molecular marker for these unique perivascular cells remains elusive. Adding to this challenge is the recent appreciation that PC populations may be heterogeneous, displaying a range of morphologies within capillary networks. We found additional support on the ultrastructural level for the classification of these PC subtypes-"thin-strand" (TSP), mesh (MP), and ensheathing (EP)-based on distinct morphological characteristics. Interestingly, we also found several examples of another cell type, likely a vascular smooth muscle cell, in a medial layer between endothelial cells (ECs) and pericytes (PCs) harboring characteristics of the ensheathing type. A conserved feature across the different PC subtypes was the presence of extracellular matrix (ECM) surrounding the vascular unit and distributed in between neighboring cells. The thickness of this vascular basement membrane was remarkably consistent depending on its location, but never strayed beyond a range of 150-300 nm unless thinned to facilitate closer proximity of neighboring cells (suggesting direct contact). The density of PC-EC contact points ("peg-and-socket" structures) was another distinguishing feature across the different PC subtypes, as were the apparent contact locations between vascular cells and brain parenchymal cells. In addition to this thinning, the extracellular matrix (ECM) surrounding EPs displayed another unique configuration in the form of extensions that emitted out radially into the surrounding parenchyma. Knowledge of the origin and function of these structures is still emerging, but their appearance suggests the potential for being mechanical elements and/or perhaps signaling nodes via embedded molecular cues. Overall, this unique ultrastructural perspective provides new insights into PC heterogeneity and the presence of medial cells within the microvessel wall, the consideration of extracellular matrix (ECM) coverage as another PC identification criteria, and unique extracellular matrix (ECM) configurations (i.e., radial extensions) that may reveal additional aspects of PC heterogeneity.
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Affiliation(s)
- Hanaa Abdelazim
- Fralin Biomedical Research Institute (FBRI) at Virginia Tech-Carilion (VTC), Roanoke, VA, United States,FBRI Center for Vascular and Heart Research, Roanoke, VA, United States
| | - Laura Beth Payne
- Fralin Biomedical Research Institute (FBRI) at Virginia Tech-Carilion (VTC), Roanoke, VA, United States,FBRI Center for Vascular and Heart Research, Roanoke, VA, United States
| | - Kyle Nolan
- Virginia Tech Carilion School of Medicine, Roanoke, VA, United States
| | - Karan Paralkar
- Fralin Biomedical Research Institute (FBRI) at Virginia Tech-Carilion (VTC), Roanoke, VA, United States
| | - Vanessa Bradley
- Fralin Biomedical Research Institute (FBRI) at Virginia Tech-Carilion (VTC), Roanoke, VA, United States
| | - Ronak Kanodia
- Fralin Biomedical Research Institute (FBRI) at Virginia Tech-Carilion (VTC), Roanoke, VA, United States
| | - Rosalie Gude
- Fralin Biomedical Research Institute (FBRI) at Virginia Tech-Carilion (VTC), Roanoke, VA, United States
| | - Rachael Ward
- Fralin Biomedical Research Institute (FBRI) at Virginia Tech-Carilion (VTC), Roanoke, VA, United States
| | - Aboozar Monavarfeshani
- Fralin Biomedical Research Institute (FBRI) at Virginia Tech-Carilion (VTC), Roanoke, VA, United States
| | - Michael A. Fox
- Fralin Biomedical Research Institute (FBRI) at Virginia Tech-Carilion (VTC), Roanoke, VA, United States,FBRI Center for Neurobiology, Roanoke, VA, United States,School of Neuroscience, Virginia Tech, Blacksburg, VA, United States
| | - John C. Chappell
- Fralin Biomedical Research Institute (FBRI) at Virginia Tech-Carilion (VTC), Roanoke, VA, United States,FBRI Center for Vascular and Heart Research, Roanoke, VA, United States,Virginia Tech Carilion School of Medicine, Roanoke, VA, United States,Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA, United States,*Correspondence: John C. Chappell,
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48
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Willi CE, Abdelazim H, Chappell JC. Evaluating cell viability, capillary perfusion, and collateral tortuosity in an ex vivo mouse intestine fluidics model. Front Bioeng Biotechnol 2022; 10:1008481. [PMID: 36568288 PMCID: PMC9780384 DOI: 10.3389/fbioe.2022.1008481] [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: 07/31/2022] [Accepted: 11/23/2022] [Indexed: 12/13/2022] Open
Abstract
Numerous disease conditions involve the sudden or progressive loss of blood flow. Perfusion restoration is vital for returning affected organs to full health. While a range of clinical interventions can successfully restore flow to downstream tissues, the microvascular responses after a loss-of-flow event can vary over time and may involve substantial microvessel instability. Increased insight into perfusion-mediated capillary stability and access-to-flow is therefore essential for advancing therapeutic reperfusion strategies and improving patient outcomes. To that end, we developed a tissue-based microvascular fluidics model to better understand (i) microvascular stability and access-to-flow over an acute time course post-ischemia, and (ii) collateral flow in vessels neighboring an occlusion site. We utilized murine intestinal tissue regions by catheterizing a feeder artery and introducing perfusate at physiologically comparable flow-rates. The cannulated vessel as well as a portion of the downstream vessels and associated intestinal tissue were cultured while constant perfusion conditions were maintained. An occlusion was introduced in a selected arterial segment, and changes in perfusion within areas receiving varying degrees of collateral flow were observed over time. To observe the microvascular response to perfusion changes, we incorporated (i) tissues harboring cell-reporter constructs, specifically Ng2-DsRed labeling of intestinal pericytes, and (ii) different types of fluorescent perfusates to quantify capillary access-to-flow at discrete time points. In our model, we found that perfusion tracers could enter capillaries within regions downstream of an occlusion upon the initial introduction of perfusion, but at 24 h tissue perfusion was severely decreased. However, live/dead cell discrimination revealed that the tissue overall did not experience significant cell death, including that of microvascular pericytes, even after 48 h. Our findings suggest that altered flow conditions may rapidly initiate cellular responses that reduce capillary access-to-flow, even in the absence of cellular deterioration or hypoxia. Overall, this ex vivo tissue-based microfluidics model may serve as a platform upon which a variety of follow-on studies may be conducted. It will thus enhance our understanding of microvessel stability and access-to-flow during an occlusive event and the role of collateral flow during normal and disrupted perfusion.
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Affiliation(s)
- Caroline E. Willi
- Fralin Biomedical Research Institute (FBRI) at Virginia Tech-Carilion (VTC), Roanoke, VA, United States,FBRI Center for Vascular and Heart Research, Roanoke, VA, United States
| | - Hanaa Abdelazim
- Fralin Biomedical Research Institute (FBRI) at Virginia Tech-Carilion (VTC), Roanoke, VA, United States,FBRI Center for Vascular and Heart Research, Roanoke, VA, United States
| | - John C. Chappell
- Fralin Biomedical Research Institute (FBRI) at Virginia Tech-Carilion (VTC), Roanoke, VA, United States,FBRI Center for Vascular and Heart Research, Roanoke, VA, United States,Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA, United States,Department of Basic Science Education, Virginia Tech Carilion School of Medicine, Roanoke, VA, United States,*Correspondence: John C. Chappell,
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49
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Carrier M, Dolhan K, Bobotis BC, Desjardins M, Tremblay MÈ. The implication of a diversity of non-neuronal cells in disorders affecting brain networks. Front Cell Neurosci 2022; 16:1015556. [PMID: 36439206 PMCID: PMC9693782 DOI: 10.3389/fncel.2022.1015556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 10/07/2022] [Indexed: 11/13/2022] Open
Abstract
In the central nervous system (CNS) neurons are classically considered the functional unit of the brain. Analysis of the physical connections and co-activation of neurons, referred to as structural and functional connectivity, respectively, is a metric used to understand their interplay at a higher level. A myriad of glial cell types throughout the brain composed of microglia, astrocytes and oligodendrocytes are key players in the maintenance and regulation of neuronal network dynamics. Microglia are the central immune cells of the CNS, able to affect neuronal populations in number and connectivity, allowing for maturation and plasticity of the CNS. Microglia and astrocytes are part of the neurovascular unit, and together they are essential to protect and supply nutrients to the CNS. Oligodendrocytes are known for their canonical role in axonal myelination, but also contribute, with microglia and astrocytes, to CNS energy metabolism. Glial cells can achieve this variety of roles because of their heterogeneous populations comprised of different states. The neuroglial relationship can be compromised in various manners in case of pathologies affecting development and plasticity of the CNS, but also consciousness and mood. This review covers structural and functional connectivity alterations in schizophrenia, major depressive disorder, and disorder of consciousness, as well as their correlation with vascular connectivity. These networks are further explored at the cellular scale by integrating the role of glial cell diversity across the CNS to explain how these networks are affected in pathology.
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Affiliation(s)
- Micaël Carrier
- Neurosciences Axis, Centre de Recherche du CHU de Québec, Université Laval, Québec City, QC, Canada
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
| | - Kira Dolhan
- Department of Psychology, University of Victoria, Victoria, BC, Canada
- Department of Biology, University of Victoria, Victoria, BC, Canada
| | | | - Michèle Desjardins
- Department of Physics, Physical Engineering and Optics, Université Laval, Québec City, QC, Canada
- Oncology Axis, Centre de Recherche du CHU de Québec, Université Laval, Québec City, QC, Canada
| | - Marie-Ève Tremblay
- Neurosciences Axis, Centre de Recherche du CHU de Québec, Université Laval, Québec City, QC, Canada
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
- Department of Molecular Medicine, Université Laval, Québec City, QC, Canada
- Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, BC, Canada
- *Correspondence: Marie-Ève Tremblay,
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50
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Tomanek RJ. The coronary capillary bed and its role in blood flow and oxygen delivery: A review. Anat Rec (Hoboken) 2022; 305:3199-3211. [PMID: 35521832 PMCID: PMC9796134 DOI: 10.1002/ar.24951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Revised: 04/19/2022] [Accepted: 04/21/2022] [Indexed: 01/01/2023]
Abstract
The assumption that the coronary capillary blood flow is exclusively regulated by precapillary vessels is not supported by recent data. Rather, the complex coronary capillary bed has unique structural and geometric characteristics that invalidate many assumptions regarding red blood cell (RBC) transport, for example, data based on a single capillary or that increases in flow are the result of capillary recruitment. It is now recognized that all coronary capillaries are open and that their variations in flow are due to structural differences, local O2 demand and delivery, and variations in hematocrit. Recent data reveal that local mechanisms within the capillary bed regulate flow via signaling mechanisms involving RBC signaling and endothelial-associated pericytes that contract and relax in response to humoral and neural signaling. The discovery that pericytes respond to vasoactive signals (e.g., nitric oxide, phenylephrine, and adenosine) underscores the role of these cells in regulating capillary diameter and consequently RBC flux and oxygen delivery. RBCs also affect blood flow by sensing <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>P</mml:mi> <mml:msub><mml:mi>O</mml:mi> <mml:mn>2</mml:mn></mml:msub> </mml:msub> </mml:math> and releasing nitric oxide to facilitate relaxation of pericytes and a consequential capillary dilation. New data indicate that these signaling mechanisms allow control of blood flow in specific coronary capillaries according to their oxygen requirements. In conclusion, mechanisms in the coronary capillary bed facilitate RBC density and transit time, hematocrit, blood flow and O2 delivery, factors that decrease capillary heterogeneity. These findings have important clinical implications for myocardial ischemia and infarction, as well as other vascular diseases.
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Affiliation(s)
- Robert J. Tomanek
- Department of Anatomy and Cell Biology, Carver College of MedicineUniversity of IowaIowa CityIAUSA
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