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van Osch MJP, Wåhlin A, Scheyhing P, Mossige I, Hirschler L, Eklund A, Mogensen K, Gomolka R, Radbruch A, Qvarlander S, Decker A, Nedergaard M, Mori Y, Eide PK, Deike K, Ringstad G. Human brain clearance imaging: Pathways taken by magnetic resonance imaging contrast agents after administration in cerebrospinal fluid and blood. NMR IN BIOMEDICINE 2024; 37:e5159. [PMID: 38634301 DOI: 10.1002/nbm.5159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 02/26/2024] [Accepted: 03/11/2024] [Indexed: 04/19/2024]
Abstract
Over the last decade, it has become evident that cerebrospinal fluid (CSF) plays a pivotal role in brain solute clearance through perivascular pathways and interactions between the brain and meningeal lymphatic vessels. Whereas most of this fundamental knowledge was gained from rodent models, human brain clearance imaging has provided important insights into the human system and highlighted the existence of important interspecies differences. Current gold standard techniques for human brain clearance imaging involve the injection of gadolinium-based contrast agents and monitoring their distribution and clearance over a period from a few hours up to 2 days. With both intrathecal and intravenous injections being used, which each have their own specific routes of distribution and thus clearance of contrast agent, a clear understanding of the kinetics associated with both approaches, and especially the differences between them, is needed to properly interpret the results. Because it is known that intrathecally injected contrast agent reaches the blood, albeit in small concentrations, and that similarly some of the intravenously injected agent can be detected in CSF, both pathways are connected and will, in theory, reach the same compartments. However, because of clear differences in relative enhancement patterns, both injection approaches will result in varying sensitivities for assessment of different subparts of the brain clearance system. In this opinion review article, the "EU Joint Programme - Neurodegenerative Disease Research (JPND)" consortium on human brain clearance imaging provides an overview of contrast agent pharmacokinetics in vivo following intrathecal and intravenous injections and what typical concentrations and concentration-time curves should be expected. This can be the basis for optimizing and interpreting contrast-enhanced MRI for brain clearance imaging. Furthermore, this can shed light on how molecules may exchange between blood, brain, and CSF.
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Affiliation(s)
- Matthias J P van Osch
- C. J. Gorter MRI Center, Department of Radiology, Leiden University Medical Center (LUMC), Leiden, The Netherlands
| | - Anders Wåhlin
- Department of Radiation Sciences, Radiation Physics, Biomedical Engineering, Umeå University, Umeå, Sweden
- Department of Applied Physics and Electronics, Umeå University, Umeå, Sweden
- Umeå Center for Functional Brain Imaging, Umeå University, Umeå, Sweden
| | - Paul Scheyhing
- Department of Neuroradiology, University Medical Center Bonn, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Ingrid Mossige
- Division of Radiology and Nuclear Medicine, Department of Physics and Computational Radiology, Oslo University Hospital, Oslo, Norway
- Institute of Clinical Medicine, The Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Lydiane Hirschler
- C. J. Gorter MRI Center, Department of Radiology, Leiden University Medical Center (LUMC), Leiden, The Netherlands
| | - Anders Eklund
- Department of Radiation Sciences, Radiation Physics, Biomedical Engineering, Umeå University, Umeå, Sweden
- Umeå Center for Functional Brain Imaging, Umeå University, Umeå, Sweden
| | - Klara Mogensen
- Department of Radiation Sciences, Radiation Physics, Biomedical Engineering, Umeå University, Umeå, Sweden
| | - Ryszard Gomolka
- Center for Translational Neuromedicine, University of Copenhagen, Copenhagen, Denmark
| | - Alexander Radbruch
- Department of Neuroradiology, University Medical Center Bonn, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Sara Qvarlander
- Department of Radiation Sciences, Radiation Physics, Biomedical Engineering, Umeå University, Umeå, Sweden
| | - Andreas Decker
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, University of Copenhagen, Copenhagen, Denmark
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, New York, USA
| | - Yuki Mori
- Center for Translational Neuromedicine, University of Copenhagen, Copenhagen, Denmark
| | - Per Kristian Eide
- Department of Neurosurgery, Oslo University Hospital-Rikshospitalet, Oslo, Norway
- KG Jebsen Centre for Brain Fluid Research, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Katerina Deike
- Department of Neuroradiology, University Medical Center Bonn, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Geir Ringstad
- Department of Radiology, Oslo University Hospital-Rikshospitalet, Oslo, Norway
- Department of Geriatrics and Internal Medicine, Sorlandet Hospital, Arendal, Norway
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2
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Smets NG, Strijkers GJ, Vinje V, Bakker ENTP. Cerebrospinal fluid turnover as a driver of brain clearance. NMR IN BIOMEDICINE 2024; 37:e5029. [PMID: 37658736 DOI: 10.1002/nbm.5029] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 06/30/2023] [Accepted: 08/05/2023] [Indexed: 09/05/2023]
Abstract
Cerebrospinal fluid (CSF) has historically been considered to function as a sink for brain-derived waste disposal. Recent work suggested that CSF interacts even more intensely with brain tissue than previously recognized, through perivascular spaces that penetrate the brain. Cardiac pulsations, vasomotion, and respiration have been suggested to drive CSF flow in these perivascular spaces, thereby enhancing waste clearance. However, the intrinsic role of CSF production in relation to its distribution volume (turnover) is not an explicit component of recent concepts on brain clearance. Here, we review the work on CSF turnover and volume, focusing on preclinical evidence. Herein, we highlight the use of MRI in establishing CSF-related parameters. We describe the impact of sleep, effect of anesthesia, aging, and hypertension on CSF turnover, and how this relates to brain clearance. Evaluation of the available evidence suggests that CSF turnover is a major determinant in brain clearance. In addition, we propose that several putative drivers of brain clearance, but also conditions associated with impaired clearance, such as aging, may actually relate to altered CSF turnover.
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Affiliation(s)
- Nina G Smets
- Department of Biomedical Engineering and Physics, Amsterdam University Medical Center, location AMC, Amsterdam, the Netherlands
- Amsterdam Cardiovascular Sciences Research Institute, Amsterdam, the Netherlands
- Amsterdam Neuroscience Research Institute, Amsterdam, the Netherlands
| | - Gustav J Strijkers
- Department of Biomedical Engineering and Physics, Amsterdam University Medical Center, location AMC, Amsterdam, the Netherlands
- Amsterdam Cardiovascular Sciences Research Institute, Amsterdam, the Netherlands
| | | | - Erik N T P Bakker
- Department of Biomedical Engineering and Physics, Amsterdam University Medical Center, location AMC, Amsterdam, the Netherlands
- Amsterdam Cardiovascular Sciences Research Institute, Amsterdam, the Netherlands
- Amsterdam Neuroscience Research Institute, Amsterdam, the Netherlands
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3
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Rivera-Rivera LA, Vikner T, Eisenmenger L, Johnson SC, Johnson KM. Four-dimensional flow MRI for quantitative assessment of cerebrospinal fluid dynamics: Status and opportunities. NMR IN BIOMEDICINE 2024; 37:e5082. [PMID: 38124351 PMCID: PMC11162953 DOI: 10.1002/nbm.5082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 10/03/2023] [Accepted: 11/07/2023] [Indexed: 12/23/2023]
Abstract
Neurological disorders can manifest with altered neurofluid dynamics in different compartments of the central nervous system. These include alterations in cerebral blood flow, cerebrospinal fluid (CSF) flow, and tissue biomechanics. Noninvasive quantitative assessment of neurofluid flow and tissue motion is feasible with phase contrast magnetic resonance imaging (PC MRI). While two-dimensional (2D) PC MRI is routinely utilized in research and clinical settings to assess flow dynamics through a single imaging slice, comprehensive neurofluid dynamic assessment can be limited or impractical. Recently, four-dimensional (4D) flow MRI (or time-resolved three-dimensional PC with three-directional velocity encoding) has emerged as a powerful extension of 2D PC, allowing for large volumetric coverage of fluid velocities at high spatiotemporal resolution within clinically reasonable scan times. Yet, most 4D flow studies have focused on blood flow imaging. Characterizing CSF flow dynamics with 4D flow (i.e., 4D CSF flow) is of high interest to understand normal brain and spine physiology, but also to study neurological disorders such as dysfunctional brain metabolite waste clearance, where CSF dynamics appear to play an important role. However, 4D CSF flow imaging is challenged by the long T1 time of CSF and slower velocities compared with blood flow, which can result in longer scan times from low flip angles and extended motion-sensitive gradients, hindering clinical adoption. In this work, we review the state of 4D CSF flow MRI including challenges, novel solutions from current research and ongoing needs, examples of clinical and research applications, and discuss an outlook on the future of 4D CSF flow.
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Affiliation(s)
- Leonardo A Rivera-Rivera
- Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Tomas Vikner
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
- Department of Radiation Sciences, Radiation Physics and Biomedical Engineering, Umeå University, Umeå, Sweden
| | - Laura Eisenmenger
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Sterling C Johnson
- Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Kevin M Johnson
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
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4
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DiNuzzo M, Dienel GA, Behar KL, Petroff OA, Benveniste H, Hyder F, Giove F, Michaeli S, Mangia S, Herculano-Houzel S, Rothman DL. Neurovascular coupling is optimized to compensate for the increase in proton production from nonoxidative glycolysis and glycogenolysis during brain activation and maintain homeostasis of pH, pCO 2, and pO 2. J Neurochem 2024; 168:632-662. [PMID: 37150946 PMCID: PMC10628336 DOI: 10.1111/jnc.15839] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 04/22/2023] [Accepted: 05/02/2023] [Indexed: 05/09/2023]
Abstract
During transient brain activation cerebral blood flow (CBF) increases substantially more than cerebral metabolic rate of oxygen consumption (CMRO2) resulting in blood hyperoxygenation, the basis of BOLD-fMRI contrast. Explanations for the high CBF versus CMRO2 slope, termed neurovascular coupling (NVC) constant, focused on maintenance of tissue oxygenation to support mitochondrial ATP production. However, paradoxically the brain has a 3-fold lower oxygen extraction fraction (OEF) than other organs with high energy requirements, like heart and muscle during exercise. Here, we hypothesize that the NVC constant and the capillary oxygen mass transfer coefficient (which in combination determine OEF) are co-regulated during activation to maintain simultaneous homeostasis of pH and partial pressure of CO2 and O2 (pCO2 and pO2). To test our hypothesis, we developed an arteriovenous flux balance model for calculating blood and brain pH, pCO2, and pO2 as a function of baseline OEF (OEF0), CBF, CMRO2, and proton production by nonoxidative metabolism coupled to ATP hydrolysis. Our model was validated against published brain arteriovenous difference studies and then used to calculate pH, pCO2, and pO2 in activated human cortex from published calibrated fMRI and PET measurements. In agreement with our hypothesis, calculated pH, pCO2, and pO2 remained close to constant independently of CMRO2 in correspondence to experimental measurements of NVC and OEF0. We also found that the optimum values of the NVC constant and OEF0 that ensure simultaneous homeostasis of pH, pCO2, and pO2 were remarkably similar to their experimental values. Thus, the high NVC constant is overall determined by proton removal by CBF due to increases in nonoxidative glycolysis and glycogenolysis. These findings resolve the paradox of the brain's high CBF yet low OEF during activation, and may contribute to explaining the vulnerability of brain function to reductions in blood flow and capillary density with aging and neurovascular disease.
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Affiliation(s)
| | - Gerald A Dienel
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR, 72205 USA
- Department of Cell Biology and Physiology, University of New Mexico School of Medicine, Albuquerque, NM, 87131 USA
| | - Kevin L Behar
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, 06511 USA
| | - Ognen A Petroff
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, 06511 USA
| | - Helene Benveniste
- Department of Anesthesiology, Yale University, New Haven, CT, 06520 USA
- Department of Biomedical Engineering, Yale University, New Haven, CT, 06520 USA
| | - Fahmeed Hyder
- Department of Biomedical Engineering, Yale University, New Haven, CT, 06520 USA
- Department of Radiology, Magnetic Resonance Research Center (MRRC), Yale University, New Haven, CT, 06520 USA
| | - Federico Giove
- Centro Ricerche Enrico Fermi, Rome, RM, 00184 Italy
- Fondazione Santa Lucia IRCCS, Rome, RM, 00179 Italy
| | - Shalom Michaeli
- Department of Radiology, Center for Magnetic Resonance Research (CMRR), University of Minnesota, Minneapolis, MN, 55455 USA
| | - Silvia Mangia
- Department of Radiology, Center for Magnetic Resonance Research (CMRR), University of Minnesota, Minneapolis, MN, 55455 USA
| | - Suzana Herculano-Houzel
- Department of Psychology, Vanderbilt University, Nashville, TN
- Department of Biological Sciences, Vanderbilt University, Nashville, TN
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN
| | - Douglas L Rothman
- Department of Biomedical Engineering, Yale University, New Haven, CT, 06520 USA
- Department of Radiology, Magnetic Resonance Research Center (MRRC), Yale University, New Haven, CT, 06520 USA
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5
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Dong Y, Xu T, Yuan L, Wang Y, Yu S, Wang Z, Chen S, Chen C, He W, Stewart T, Zhang W, Yang X. Cerebrospinal fluid efflux through dynamic paracellular pores on venules as a missing piece of the brain drainage system. EXPLORATION (BEIJING, CHINA) 2024; 4:20230029. [PMID: 38855622 PMCID: PMC11022608 DOI: 10.1002/exp.20230029] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 10/31/2023] [Indexed: 06/11/2024]
Abstract
The glymphatic system plays a key role in the clearance of waste from the parenchyma, and its dysfunction has been associated with the pathogenesis of Alzheimer's disease (AD). However, questions remain regarding its complete mechanisms. Here, we report that efflux of cerebrospinal fluid (CSF)/interstitial fluid (ISF) solutes occurs through a triphasic process that cannot be explained by the current model, but rather hints at the possibility of other, previously undiscovered routes from paravenous spaces to the blood. Using real-time, in vivo observation of efflux, a novel drainage pathway was discovered, in which CSF molecules enter the bloodstream directly through dynamically assembled, trumpet-shaped pores (basolateral ϕ<8 μm; apical ϕ < 2 μm) on the walls of brain venules. As Zn2+ could facilitate the brain clearance of macromolecular ISF solutes, Zn2+-induced reconstruction of the tight junctions (TJs) in vascular endothelial cells may participate in pore formation. Thus, an updated model for glymphatic clearance of brain metabolites and potential regulation is postulated. In addition, deficient clearance of Aβ through these asymmetric venule pores was observed in AD model mice, supporting the notion that impaired brain drainage function contributes to Aβ accumulation and pathogenic dilation of the perivascular space in AD.
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Affiliation(s)
- Yaqiong Dong
- Institute of Translational Medicine, The Affiliated Hospital of Qingdao University, College of MedicineQingdao UniversityQingdaoChina
- The State Key Laboratories of Natural and Biomimetic Drugs and Department of Chemical Biology, School of Pharmaceutical SciencesPeking University Health Science CenterBeijingChina
| | - Ting Xu
- The State Key Laboratories of Natural and Biomimetic Drugs and Department of Chemical Biology, School of Pharmaceutical SciencesPeking University Health Science CenterBeijingChina
| | - Lan Yuan
- The State Key Laboratories of Natural and Biomimetic Drugs and Department of Chemical Biology, School of Pharmaceutical SciencesPeking University Health Science CenterBeijingChina
| | - Yahan Wang
- The State Key Laboratories of Natural and Biomimetic Drugs and Department of Chemical Biology, School of Pharmaceutical SciencesPeking University Health Science CenterBeijingChina
| | - Siwang Yu
- The State Key Laboratories of Natural and Biomimetic Drugs and Department of Chemical Biology, School of Pharmaceutical SciencesPeking University Health Science CenterBeijingChina
| | - Zhi Wang
- The State Key Laboratories of Natural and Biomimetic Drugs and Department of Chemical Biology, School of Pharmaceutical SciencesPeking University Health Science CenterBeijingChina
| | - Shizhu Chen
- The National Institutes of Pharmaceutical R&D Co., Ltd.China Resources Pharmaceutical Group LimitedBeijingChina
| | - Chunhua Chen
- Department of Anatomy and HistologyPeking University Health Science CenterBeijingChina
| | - Weijiang He
- State Key Laboratory of Coordination Chemistry, Coordination Chemistry Institute, School of Chemistry and Chemical EngineeringNanjing UniversityNanjingChina
| | - Tessandra Stewart
- Department of PathologyUniversity of Washington School of MedicineSeattleWashingtonUSA
| | - Weiguang Zhang
- Department of Anatomy and HistologyPeking University Health Science CenterBeijingChina
| | - Xiaoda Yang
- The State Key Laboratories of Natural and Biomimetic Drugs and Department of Chemical Biology, School of Pharmaceutical SciencesPeking University Health Science CenterBeijingChina
- SATCM Key Laboratory of Compound Drug DetoxificationPeking University Health Science CenterBeijingChina
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6
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Agarwal N, Lewis LD, Hirschler L, Rivera LR, Naganawa S, Levendovszky SR, Ringstad G, Klarica M, Wardlaw J, Iadecola C, Hawkes C, Octavia Carare R, Wells J, Bakker EN, Kurtcuoglu V, Bilston L, Nedergaard M, Mori Y, Stoodley M, Alperin N, de Leon M, van Osch MJ. Current Understanding of the Anatomy, Physiology, and Magnetic Resonance Imaging of Neurofluids: Update From the 2022 "ISMRM Imaging Neurofluids Study group" Workshop in Rome. J Magn Reson Imaging 2024; 59:431-449. [PMID: 37141288 PMCID: PMC10624651 DOI: 10.1002/jmri.28759] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 04/18/2023] [Accepted: 04/18/2023] [Indexed: 05/05/2023] Open
Abstract
Neurofluids is a term introduced to define all fluids in the brain and spine such as blood, cerebrospinal fluid, and interstitial fluid. Neuroscientists in the past millennium have steadily identified the several different fluid environments in the brain and spine that interact in a synchronized harmonious manner to assure a healthy microenvironment required for optimal neuroglial function. Neuroanatomists and biochemists have provided an incredible wealth of evidence revealing the anatomy of perivascular spaces, meninges and glia and their role in drainage of neuronal waste products. Human studies have been limited due to the restricted availability of noninvasive imaging modalities that can provide a high spatiotemporal depiction of the brain neurofluids. Therefore, animal studies have been key in advancing our knowledge of the temporal and spatial dynamics of fluids, for example, by injecting tracers with different molecular weights. Such studies have sparked interest to identify possible disruptions to neurofluids dynamics in human diseases such as small vessel disease, cerebral amyloid angiopathy, and dementia. However, key differences between rodent and human physiology should be considered when extrapolating these findings to understand the human brain. An increasing armamentarium of noninvasive MRI techniques is being built to identify markers of altered drainage pathways. During the three-day workshop organized by the International Society of Magnetic Resonance in Medicine that was held in Rome in September 2022, several of these concepts were discussed by a distinguished international faculty to lay the basis of what is known and where we still lack evidence. We envision that in the next decade, MRI will allow imaging of the physiology of neurofluid dynamics and drainage pathways in the human brain to identify true pathological processes underlying disease and to discover new avenues for early diagnoses and treatments including drug delivery. Evidence level: 1 Technical Efficacy: Stage 3.
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Affiliation(s)
- Nivedita Agarwal
- Neuroradiology Unit, Scientific Institute IRCCS E. Medea, Bosisio Parini, Italy
| | - Laura D. Lewis
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, USA
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Lydiane Hirschler
- C.J. Gorter MRI Center, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Leonardo Rivera Rivera
- Wisconsin Alzheimer’s Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Shinji Naganawa
- Department of Radiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | | | - Geir Ringstad
- Department of Radiology, Oslo University Hospital Rikshospitalet, Oslo, Norway
- Department of Geriatrics and Internal Medicine, Sorlandet Hospital, Arendal, Norway
| | - Marijan Klarica
- Department of Pharmacology and Croatian Institute of Brain Research, University of Zagreb School of Medicine, Zagreb, Croatia
| | - Joanna Wardlaw
- Centre for Clinical Brain Sciences and UK Dementia Research Institute Centre, University of Edinburgh, Edinburgh, UK
| | - Costantino Iadecola
- Department of Pharmacology and Croatian Institute of Brain Research, University of Zagreb School of Medicine, Zagreb, Croatia
| | - Cheryl Hawkes
- Biomedical and Life Sciences, Lancaster University, Lancaster, UK
| | | | - Jack Wells
- UCL Centre for Advanced Biomedical Imaging, University College of London, London, UK
| | - Erik N.T.P. Bakker
- Biomedical Engineering and Physics, Amsterdam UMC, University of Amsterdam, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | | | - Lynne Bilston
- Neuroscience Research Australia and UNSW Medicine, Sydney, Australia
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, New York, USA
- Center for Translational Neuromedicine, University of Copenhagen, Copenhagen, Denmark
| | - Yuki Mori
- Center for Translational Neuromedicine, University of Copenhagen, Copenhagen, Denmark
| | - Marcus Stoodley
- Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, Australia
- Department of Neurosurgery, Macquarie University Hospital, Sydney, Australia
| | - Noam Alperin
- Department of Radiology and Biomedical Engineering, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Mony de Leon
- Weil Cornell Medicine, Department of Radiology, Brain Health Imaging Institute, New York City, New York, USA
| | - Matthias J.P. van Osch
- C.J. Gorter MRI Center, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
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7
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Zedde M, Grisendi I, Assenza F, Vandelli G, Napoli M, Moratti C, Lochner P, Seiffge DJ, Piazza F, Valzania F, Pascarella R. The Venular Side of Cerebral Amyloid Angiopathy: Proof of Concept of a Neglected Issue. Biomedicines 2023; 11:2663. [PMID: 37893037 PMCID: PMC10604278 DOI: 10.3390/biomedicines11102663] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 09/23/2023] [Accepted: 09/25/2023] [Indexed: 10/29/2023] Open
Abstract
Small vessel diseases (SVD) is an umbrella term including several entities affecting small arteries, arterioles, capillaries, and venules in the brain. One of the most relevant and prevalent SVDs is cerebral amyloid angiopathy (CAA), whose pathological hallmark is the deposition of amyloid fragments in the walls of small cortical and leptomeningeal vessels. CAA frequently coexists with Alzheimer's Disease (AD), and both are associated with cerebrovascular events, cognitive impairment, and dementia. CAA and AD share pathophysiological, histopathological and neuroimaging issues. The venular involvement in both diseases has been neglected, although both animal models and human histopathological studies found a deposition of amyloid beta in cortical venules. This review aimed to summarize the available information about venular involvement in CAA, starting from the biological level with the putative pathomechanisms of cerebral damage, passing through the definition of the peculiar angioarchitecture of the human cortex with the functional organization and consequences of cortical arteriolar and venular occlusion, and ending to the hypothesized links between cortical venular involvement and the main neuroimaging markers of the disease.
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Affiliation(s)
- Marialuisa Zedde
- Neurology Unit, Stroke Unit, AUSL-IRCCS di Reggio Emilia, Via Amendola 2, 42122 Reggio Emilia, Italy
| | - Ilaria Grisendi
- Neurology Unit, Stroke Unit, AUSL-IRCCS di Reggio Emilia, Via Amendola 2, 42122 Reggio Emilia, Italy
| | - Federica Assenza
- Neurology Unit, Stroke Unit, AUSL-IRCCS di Reggio Emilia, Via Amendola 2, 42122 Reggio Emilia, Italy
| | - Gabriele Vandelli
- Neurology Unit, Stroke Unit, AUSL-IRCCS di Reggio Emilia, Via Amendola 2, 42122 Reggio Emilia, Italy
| | - Manuela Napoli
- Neuroradiology Unit, AUSL-IRCCS di Reggio Emilia, Via Amendola 2, 42122 Reggio Emilia, Italy
| | - Claudio Moratti
- Neuroradiology Unit, AUSL-IRCCS di Reggio Emilia, Via Amendola 2, 42122 Reggio Emilia, Italy
| | - Piergiorgio Lochner
- Department of Neurology, Saarland University Medical Center, 66421 Homburg, Germany;
| | - David J. Seiffge
- Department of Neurology, Inselspital, Bern University Hospital, University of Bern, 3010 Bern, Switzerland
| | - Fabrizio Piazza
- CAA and AD Translational Research and Biomarkers Laboratory, School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900 Monza, Italy;
| | - Franco Valzania
- Neurology Unit, Stroke Unit, AUSL-IRCCS di Reggio Emilia, Via Amendola 2, 42122 Reggio Emilia, Italy
| | - Rosario Pascarella
- Neuroradiology Unit, AUSL-IRCCS di Reggio Emilia, Via Amendola 2, 42122 Reggio Emilia, Italy
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8
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Ciurea AV, Mohan AG, Covache-Busuioc RA, Costin HP, Saceleanu VM. The Brain's Glymphatic System: Drawing New Perspectives in Neuroscience. Brain Sci 2023; 13:1005. [PMID: 37508938 PMCID: PMC10377460 DOI: 10.3390/brainsci13071005] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 06/16/2023] [Accepted: 06/26/2023] [Indexed: 07/30/2023] Open
Abstract
This paper delves into the intricate structure and functionality of the brain's glymphatic system, bringing forth new dimensions in its neuroscientific understanding. This paper commences by exploring the cerebrospinal fluid (CSF)-its localization, production, and pivotal role within the central nervous system, acting as a cushion and vehicle for nutrient distribution and waste elimination. We then transition into an in-depth study of the morphophysiological aspects of the glymphatic system, a recent discovery revolutionizing the perception of waste clearance from the brain, highlighting its lymphatic-like characteristics and remarkable operations. This paper subsequently emphasizes the glymphatic system's potential implications in Alzheimer's disease (AD), discussing the connection between inefficient glymphatic clearance and AD pathogenesis. This review also elucidates the intriguing interplay between the glymphatic system and the circadian rhythm, illustrating the optimal functioning of glymphatic clearance during sleep. Lastly, we underscore the hitherto underappreciated involvement of the glymphatic system in the tumoral microenvironment, potentially impacting tumor growth and progression. This comprehensive paper accentuates the glymphatic system's pivotal role in multiple domains, fostering an understanding of the brain's waste clearance mechanisms and offering avenues for further research into neuropathological conditions.
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Affiliation(s)
- Alexandru Vlad Ciurea
- Neurosurgery Department, "Carol Davila" University of Medicine and Pharmacy, 020021 Bucharest, Romania
- Neurosurgery Department, Sanador Clinical Hospital, 010991 Bucharest, Romania
| | - Aurel George Mohan
- Department of Neurosurgery, Bihor County Emergency Clinical Hospital, 410167 Oradea, Romania
- Department of Neurosurgery, Faculty of Medicine, Oradea University, 410610 Oradea, Romania
| | | | - Horia Petre Costin
- Neurosurgery Department, "Carol Davila" University of Medicine and Pharmacy, 020021 Bucharest, Romania
| | - Vicentiu Mircea Saceleanu
- Neurosurgery Department, Sibiu County Emergency Hospital, 550245 Sibiu, Romania
- Department of Neurosurgery, "Lucian Blaga" University of Medicine, 550024 Sibiu, Romania
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9
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Iadecola C, Smith EE, Anrather J, Gu C, Mishra A, Misra S, Perez-Pinzon MA, Shih AY, Sorond FA, van Veluw SJ, Wellington CL. The Neurovasculome: Key Roles in Brain Health and Cognitive Impairment: A Scientific Statement From the American Heart Association/American Stroke Association. Stroke 2023; 54:e251-e271. [PMID: 37009740 PMCID: PMC10228567 DOI: 10.1161/str.0000000000000431] [Citation(s) in RCA: 36] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2023]
Abstract
BACKGROUND Preservation of brain health has emerged as a leading public health priority for the aging world population. Advances in neurovascular biology have revealed an intricate relationship among brain cells, meninges, and the hematic and lymphatic vasculature (the neurovasculome) that is highly relevant to the maintenance of cognitive function. In this scientific statement, a multidisciplinary team of experts examines these advances, assesses their relevance to brain health and disease, identifies knowledge gaps, and provides future directions. METHODS Authors with relevant expertise were selected in accordance with the American Heart Association conflict-of-interest management policy. They were assigned topics pertaining to their areas of expertise, reviewed the literature, and summarized the available data. RESULTS The neurovasculome, composed of extracranial, intracranial, and meningeal vessels, as well as lymphatics and associated cells, subserves critical homeostatic functions vital for brain health. These include delivering O2 and nutrients through blood flow and regulating immune trafficking, as well as clearing pathogenic proteins through perivascular spaces and dural lymphatics. Single-cell omics technologies have unveiled an unprecedented molecular heterogeneity in the cellular components of the neurovasculome and have identified novel reciprocal interactions with brain cells. The evidence suggests a previously unappreciated diversity of the pathogenic mechanisms by which disruption of the neurovasculome contributes to cognitive dysfunction in neurovascular and neurodegenerative diseases, providing new opportunities for the prevention, recognition, and treatment of these conditions. CONCLUSIONS These advances shed new light on the symbiotic relationship between the brain and its vessels and promise to provide new diagnostic and therapeutic approaches for brain disorders associated with cognitive dysfunction.
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10
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Han G, Zhou Y, Zhang K, Jiao B, Hu J, Zhang Y, Wang Z, Lou M, Bai R. Age- and time-of-day dependence of glymphatic function in the human brain measured via two diffusion MRI methods. Front Aging Neurosci 2023; 15:1173221. [PMID: 37284019 PMCID: PMC10239807 DOI: 10.3389/fnagi.2023.1173221] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 05/04/2023] [Indexed: 06/08/2023] Open
Abstract
Advanced age, accompanied by impaired glymphatic function, is a key risk factor for many neurodegenerative diseases. To study age-related differences in the human glymphatic system, we measured the influx and efflux activities of the glymphatic system via two non-invasive diffusion magnetic resonance imaging (MRI) methods, ultra-long echo time and low-b diffusion tensor imaging (DTIlow-b) measuring the subarachnoid space (SAS) flow along the middle cerebral artery and DTI analysis along the perivascular space (DTI-ALPS) along medullary veins in 22 healthy volunteers (aged 21-75 years). We first evaluated the circadian rhythm dependence of the glymphatic activity by repeating the MRI measurements at five time points from 8:00 to 23:00 and found no time-of-day dependence in the awake state under the current sensitivity of MRI measurements. Further test-retest analysis demonstrated high repeatability of both diffusion MRI measurements, suggesting their reliability. Additionally, the influx rate of the glymphatic system was significantly higher in participants aged >45 years than in participants aged 21-38, while the efflux rate was significantly lower in those aged >45 years. The mismatched influx and efflux activities in the glymphatic system might be due to age-related changes in arterial pulsation and aquaporin-4 polarization.
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Affiliation(s)
- Guangxu Han
- Department of Physical Medicine and Rehabilitation of the Affiliated Sir Run Shaw Hospital AND Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Zhejiang University, Hangzhou, China
- Key Laboratory of Biomedical Engineering of Education Ministry, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, China
| | - Ying Zhou
- Department of Neurology, School of Medicine, The Second Affiliated Hospital of Zhejiang University, Hangzhou, China
| | - Kemeng Zhang
- Department of Neurology, School of Medicine, The Second Affiliated Hospital of Zhejiang University, Hangzhou, China
| | - Bingjie Jiao
- Department of Physical Medicine and Rehabilitation of the Affiliated Sir Run Shaw Hospital AND Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Zhejiang University, Hangzhou, China
- Key Laboratory of Biomedical Engineering of Education Ministry, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, China
| | - Junwen Hu
- Department of Neurosurgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
- Clinical Research Center for Neurological Diseases of Zhejiang Province, Hangzhou, China
| | - Yifan Zhang
- Department of Physical Medicine and Rehabilitation of the Affiliated Sir Run Shaw Hospital AND Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Zhejiang University, Hangzhou, China
- Key Laboratory of Biomedical Engineering of Education Ministry, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, China
| | - Zejun Wang
- Department of Physical Medicine and Rehabilitation of the Affiliated Sir Run Shaw Hospital AND Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Zhejiang University, Hangzhou, China
- Key Laboratory of Biomedical Engineering of Education Ministry, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, China
| | - Min Lou
- Department of Neurology, School of Medicine, The Second Affiliated Hospital of Zhejiang University, Hangzhou, China
| | - Ruiliang Bai
- Department of Physical Medicine and Rehabilitation of the Affiliated Sir Run Shaw Hospital AND Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Zhejiang University, Hangzhou, China
- Key Laboratory of Biomedical Engineering of Education Ministry, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, China
- MOE Frontier Science Center for Brain Science and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, China
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11
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Williams SD, Setzer B, Fultz NE, Valdiviezo Z, Tacugue N, Diamandis Z, Lewis LD. Neural activity induced by sensory stimulation can drive large-scale cerebrospinal fluid flow during wakefulness in humans. PLoS Biol 2023; 21:e3002035. [PMID: 36996009 PMCID: PMC10062585 DOI: 10.1371/journal.pbio.3002035] [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: 08/08/2022] [Accepted: 02/15/2023] [Indexed: 03/31/2023] Open
Abstract
Cerebrospinal fluid (CSF) flow maintains healthy brain homeostasis, facilitating solute transport and the exchange of brain waste products. CSF flow is thus important for brain health, but the mechanisms that control its large-scale movement through the ventricles are not well understood. While it is well established that CSF flow is modulated by respiratory and cardiovascular dynamics, recent work has also demonstrated that neural activity is coupled to large waves of CSF flow in the ventricles during sleep. To test whether the temporal coupling between neural activity and CSF flow is in part due to a causal relationship, we investigated whether CSF flow could be induced by driving neural activity with intense visual stimulation. We manipulated neural activity with a flickering checkerboard visual stimulus and found that we could drive macroscopic CSF flow in the human brain. The timing and amplitude of CSF flow was matched to the visually evoked hemodynamic responses, suggesting neural activity can modulate CSF flow via neurovascular coupling. These results demonstrate that neural activity can contribute to driving CSF flow in the human brain and that the temporal dynamics of neurovascular coupling can explain this effect.
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Affiliation(s)
- Stephanie D. Williams
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
- Department of Psychological and Brain Sciences, Boston University, Boston, Massachusetts, United States of America
| | - Beverly Setzer
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
- Graduate Program in Neuroscience, Boston University, Boston, Massachusetts, United States of America
| | - Nina E. Fultz
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
| | - Zenia Valdiviezo
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
| | - Nicole Tacugue
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
| | - Zachary Diamandis
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
| | - Laura D. Lewis
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
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12
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Poulain A, Riseth J, Vinje V. Multi-compartmental model of glymphatic clearance of solutes in brain tissue. PLoS One 2023; 18:e0280501. [PMID: 36881576 PMCID: PMC9990927 DOI: 10.1371/journal.pone.0280501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 01/02/2023] [Indexed: 03/08/2023] Open
Abstract
The glymphatic system is the subject of numerous pieces of research in biology. Mathematical modelling plays a considerable role in this field since it can indicate the possible physical effects of this system and validate the biologists' hypotheses. The available mathematical models that describe the system at the scale of the brain (i.e. the macroscopic scale) are often solely based on the diffusion equation and do not consider the fine structures formed by the perivascular spaces. We therefore propose a mathematical model representing the time and space evolution of a mixture flowing through multiple compartments of the brain. We adopt a macroscopic point of view in which the compartments are all present at any point in space. The equations system is composed of two coupled equations for each compartment: One equation for the pressure of a fluid and one for the mass concentration of a solute. The fluid and solute can move from one compartment to another according to certain membrane conditions modelled by transfer functions. We propose to apply this new modelling framework to the clearance of 14C-inulin from the rat brain.
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Affiliation(s)
- Alexandre Poulain
- Laboratoire Paul Painlevé, UMR 8524 CNRS, Université de Lille, Lille, France
- Department for Numerical Analysis and Scientific Computing, Simula Research Laboratory, Oslo, Norway
- * E-mail:
| | - Jørgen Riseth
- Department of Mathematics, University of Oslo, Oslo, Norway
- Department for Numerical Analysis and Scientific Computing, Simula Research Laboratory, Oslo, Norway
| | - Vegard Vinje
- Department for Numerical Analysis and Scientific Computing, Simula Research Laboratory, Oslo, Norway
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13
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Semyachkina-Glushkovskaya OV, Postnov DE, Khorovodov AP, Navolokin NA, Kurthz JHG. Lymphatic Drainage System of the Brain: a New Player in Neuroscience. J EVOL BIOCHEM PHYS+ 2023. [DOI: 10.1134/s0022093023010015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
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14
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Soden PA, Henderson AR, Lee E. A Microfluidic Model of AQP4 Polarization Dynamics and Fluid Transport in the Healthy and Inflamed Human Brain: The First Step Towards Glymphatics-on-a-Chip. Adv Biol (Weinh) 2022; 6:e2200027. [PMID: 35922370 PMCID: PMC9771879 DOI: 10.1002/adbi.202200027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 07/01/2022] [Indexed: 01/28/2023]
Abstract
Dysfunction of the aquaporin-4 (AQP4)-dependent glymphatic waste clearance pathway has recently been implicated in the pathogenesis of several neurodegenerative diseases. However, it is difficult to unravel the causative relationship between glymphatic dysfunction, AQP4 depolarization, protein aggregation, and inflammation in neurodegeneration using animal models alone. There is currently a clear, unmet need for in vitro models of the brain's waterscape, and the first steps towards a bona fide "glymphatics-on-a-chip" are taken in the present study. It is demonstrated that chronic exposure to lipopolysaccharide (LPS), amyloid-β(1-42) oligomers, and an AQP4 inhibitor impairs the drainage of fluid and amyloid-β(1-40) tracer in a gliovascular unit (GVU)-on-a-chip model containing human astrocytes and brain microvascular endothelial cells. The LPS-induced drainage impairment is partially retained following cell lysis, indicating that neuroinflammation induces parallel changes in cell-dependent and matrisome-dependent fluid transport pathways in GVU-on-a-chip. Additionally, AQP4 depolarization is observed following LPS treatment, suggesting that LPS-induced drainage impairments on-chip may be driven in part by changes in AQP4-dependent fluid dynamics.
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Affiliation(s)
- Paul A Soden
- College of Human Ecology, Cornell University, Ithaca, NY, 14853, USA
| | - Aria R Henderson
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Esak Lee
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, 14853, USA
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15
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Zhao L, Tannenbaum A, Bakker ENTP, Benveniste H. Physiology of Glymphatic Solute Transport and Waste Clearance from the Brain. Physiology (Bethesda) 2022; 37:0. [PMID: 35881783 PMCID: PMC9550574 DOI: 10.1152/physiol.00015.2022] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 07/12/2022] [Accepted: 07/20/2022] [Indexed: 12/25/2022] Open
Abstract
This review focuses on the physiology of glymphatic solute transport and waste clearance, using evidence from experimental animal models as well as from human studies. Specific topics addressed include the biophysical characteristics of fluid and solute transport in the central nervous system, glymphatic-lymphatic coupling, as well as the role of cerebrospinal fluid movement for brain waste clearance. We also discuss the current understanding of mechanisms underlying increased waste clearance during sleep.
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Affiliation(s)
- Lucy Zhao
- Department of Anesthesiology, Yale School of Medicine, New Haven, Connecticut
| | - Allen Tannenbaum
- Departments of Computer Science and Applied Mathematics and Statistics, Stony Brook University, Stony Brook, New York
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York City, New York
| | - Erik N T P Bakker
- Department of Biomedical Engineering and Physics, Amsterdam UMC, Amsterdam Cardiovascular Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Helene Benveniste
- Department of Anesthesiology, Yale School of Medicine, New Haven, Connecticut
- Department of Biomedical Engineering, Yale School of Medicine, New Haven, Connecticut
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16
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Abstract
The brain harbors a unique ability to, figuratively speaking, shift its gears. During wakefulness, the brain is geared fully toward processing information and behaving, while homeostatic functions predominate during sleep. The blood-brain barrier establishes a stable environment that is optimal for neuronal function, yet the barrier imposes a physiological problem; transcapillary filtration that forms extracellular fluid in other organs is reduced to a minimum in brain. Consequently, the brain depends on a special fluid [the cerebrospinal fluid (CSF)] that is flushed into brain along the unique perivascular spaces created by astrocytic vascular endfeet. We describe this pathway, coined the term glymphatic system, based on its dependency on astrocytic vascular endfeet and their adluminal expression of aquaporin-4 water channels facing toward CSF-filled perivascular spaces. Glymphatic clearance of potentially harmful metabolic or protein waste products, such as amyloid-β, is primarily active during sleep, when its physiological drivers, the cardiac cycle, respiration, and slow vasomotion, together efficiently propel CSF inflow along periarterial spaces. The brain's extracellular space contains an abundance of proteoglycans and hyaluronan, which provide a low-resistance hydraulic conduit that rapidly can expand and shrink during the sleep-wake cycle. We describe this unique fluid system of the brain, which meets the brain's requisites to maintain homeostasis similar to peripheral organs, considering the blood-brain-barrier and the paths for formation and egress of the CSF.
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Affiliation(s)
- Martin Kaag Rasmussen
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Humberto Mestre
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, New York
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, New York
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17
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Perivascular pumping in the mouse brain: Improved boundary conditions reconcile theory, simulation, and experiment. J Theor Biol 2022; 542:111103. [PMID: 35339513 DOI: 10.1016/j.jtbi.2022.111103] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 02/16/2022] [Accepted: 03/17/2022] [Indexed: 01/24/2023]
Abstract
Cerebrospinal fluid (CSF) flows through the perivascular spaces (PVSs) surrounding cerebral arteries. Revealing the mechanisms driving that flow could bring improved understanding of brain waste transport and insights for disorders including Alzheimer's disease and stroke. In vivo velocity measurements of CSF in surface PVSs in mice have been used to argue that flow is driven primarily by the pulsatile motion of artery walls - perivascular pumping. However, fluid dynamics theory and simulation have predicted that perivascular pumping produces flows differing from in vivo observations starkly, particularly in the phase and relative amplitude of flow oscillation. We show that coupling theoretical and simulated flows to more realistic end boundary conditions, using resistance and compliance values measured in mice instead of using periodic boundaries, results in velocities that match observations more closely in phase and relative amplitude of oscillation, while preserving the existing agreement in mean flow speed. This quantitative agreement among theory, simulation, and in vivo measurement further supports the idea that perivascular pumping is an important CSF driver in physiological conditions.
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18
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Hladky SB, Barrand MA. The glymphatic hypothesis: the theory and the evidence. Fluids Barriers CNS 2022; 19:9. [PMID: 35115036 PMCID: PMC8815211 DOI: 10.1186/s12987-021-00282-z] [Citation(s) in RCA: 87] [Impact Index Per Article: 43.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 10/15/2021] [Indexed: 12/13/2022] Open
Abstract
The glymphatic hypothesis proposes a mechanism for extravascular transport into and out of the brain of hydrophilic solutes unable to cross the blood-brain barrier. It suggests that there is a circulation of fluid carrying solutes inwards via periarterial routes, through the interstitium and outwards via perivenous routes. This review critically analyses the evidence surrounding the mechanisms involved in each of these stages. There is good evidence that both influx and efflux of solutes occur along periarterial routes but no evidence that the principal route of outflow is perivenous. Furthermore, periarterial inflow of fluid is unlikely to be adequate to provide the outflow that would be needed to account for solute efflux. A tenet of the hypothesis is that flow sweeps solutes through the parenchyma. However, the velocity of any possible circulatory flow within the interstitium is too small compared to diffusion to provide effective solute movement. By comparison the earlier classical hypothesis describing extravascular transport proposed fluid entry into the parenchyma across the blood-brain barrier, solute movements within the parenchyma by diffusion, and solute efflux partly by diffusion near brain surfaces and partly carried by flow along "preferred routes" including perivascular spaces, white matter tracts and subependymal spaces. It did not suggest fluid entry via periarterial routes. Evidence is still incomplete concerning the routes and fate of solutes leaving the brain. A large proportion of the solutes eliminated from the parenchyma go to lymph nodes before reaching blood but the proportions delivered directly to lymph or indirectly via CSF which then enters lymph are as yet unclear. In addition, still not understood is why and how the absence of AQP4 which is normally highly expressed on glial endfeet lining periarterial and perivenous routes reduces rates of solute elimination from the parenchyma and of solute delivery to it from remote sites of injection. Neither the glymphatic hypothesis nor the earlier classical hypothesis adequately explain how solutes and fluid move into, through and out of the brain parenchyma. Features of a more complete description are discussed. All aspects of extravascular transport require further study.
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Affiliation(s)
- Stephen B. Hladky
- Department of Pharmacology, University of Cambridge, Cambridge, CB2 1PD UK
| | - Margery A. Barrand
- Department of Pharmacology, University of Cambridge, Cambridge, CB2 1PD UK
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19
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Cousins O, Hodges A, Schubert J, Veronese M, Turkheimer F, Miyan J, Engelhardt B, Roncaroli F. The Blood‐CSF‐Brain Route of Neurological Disease: The Indirect Pathway into the Brain. Neuropathol Appl Neurobiol 2021; 48:e12789. [DOI: 10.1111/nan.12789] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 12/08/2021] [Accepted: 12/14/2021] [Indexed: 11/26/2022]
Affiliation(s)
- Oliver Cousins
- Department of Neuroimaging, IoPPN, King’s College London London United Kingdom
| | - Angela Hodges
- Department of Old Age Psychiatry, IoPPN, King’s College London London United Kingdom
| | - Julia Schubert
- Department of Neuroimaging, IoPPN, King’s College London London United Kingdom
| | - Mattia Veronese
- Department of Neuroimaging, IoPPN, King’s College London London United Kingdom
| | - Federico Turkheimer
- Department of Neuroimaging, IoPPN, King’s College London London United Kingdom
| | - Jaleel Miyan
- Division of Neuroscience and Experimental Psychology School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, M13 9PL
| | | | - Federico Roncaroli
- Division of Neuroscience and Experimental Psychology School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, M13 9PL
- Geoffrey Jefferson Brain Research Centre; Manchester Academic Health Science Centre Manchester UK
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20
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Abstract
Sleep is essential for brain function in a surprisingly diverse set of ways. In the short term, lack of sleep leads to impaired memory and attention; in the longer term, it produces neurological dysfunction or even death. I discuss recent advances in understanding how sleep maintains the physiological health of the brain through interconnected systems of neuronal activity and fluid flow. The neural dynamics that appear during sleep are intrinsically coupled to its consequences for blood flow, cerebrospinal fluid dynamics, and waste clearance. Recognizing these linked causes and consequences of sleep has shed new light on why sleep is important for such disparate aspects of brain function.
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Affiliation(s)
- Laura D Lewis
- Department of Biomedical Engineering, Boston University, Boston, MA, USA, and Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, USA
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21
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Klostranec JM, Vucevic D, Bhatia KD, Kortman HGJ, Krings T, Murphy KP, terBrugge KG, Mikulis DJ. Current Concepts in Intracranial Interstitial Fluid Transport and the Glymphatic System: Part I-Anatomy and Physiology. Radiology 2021; 301:502-514. [PMID: 34665028 DOI: 10.1148/radiol.2021202043] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Normal physiologic function of organs requires a circulation of interstitial fluid to deliver nutrients and clear cellular waste products. Lymphatic vessels serve as collectors of this fluid in most organs; however, these vessels are absent in the central nervous system. How the central nervous system maintains tight control of extracellular conditions has been a fundamental question in neuroscience until recent discovery of the glial-lymphatic, or glymphatic, system was made this past decade. Networks of paravascular channels surrounding pial and parenchymal arteries and veins were found that extend into the walls of capillaries to allow fluid transport and exchange between the interstitial and cerebrospinal fluid spaces. The currently understood anatomy and physiology of the glymphatic system is reviewed, with the paravascular space presented as an intrinsic component of healthy pial and parenchymal cerebral blood vessels. Glymphatic system behavior in animal models of health and disease, and its enhanced function during sleep, are discussed. The evolving understanding of glymphatic system characteristics is then used to provide a current interpretation of its physiology that can be helpful for radiologists when interpreting neuroimaging investigations.
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Affiliation(s)
- Jesse M Klostranec
- From the Montreal Neurologic Institute and Hospital, Department of Diagnostic and Interventional Neuroradiology, McGill University Health Centre, 3801 Rue University, Montréal, QC, Canada H3A 2B4 (J.M.K.); Department of Medical Imaging, University of Toronto, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Division of Neuroradiology, Toronto Western Hospital, University Health Network, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Centre Hospitalier de l'Université de Montreal (CHUM), Department of Radiology, Service of Neuroradiology, l'Université de Montreal, Montréal, Canada (J.M.K.); Department of Materials Science & Engineering, Faculty of Applied Science & Engineering, University of Toronto, Toronto, Canada (D.V.); Department of Medical Imaging, Sydney Children's Hospitals Network, Westmead, Australia (K.D.B.); and Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Canada (T.K., K.G.t.B.)
| | - Diana Vucevic
- From the Montreal Neurologic Institute and Hospital, Department of Diagnostic and Interventional Neuroradiology, McGill University Health Centre, 3801 Rue University, Montréal, QC, Canada H3A 2B4 (J.M.K.); Department of Medical Imaging, University of Toronto, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Division of Neuroradiology, Toronto Western Hospital, University Health Network, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Centre Hospitalier de l'Université de Montreal (CHUM), Department of Radiology, Service of Neuroradiology, l'Université de Montreal, Montréal, Canada (J.M.K.); Department of Materials Science & Engineering, Faculty of Applied Science & Engineering, University of Toronto, Toronto, Canada (D.V.); Department of Medical Imaging, Sydney Children's Hospitals Network, Westmead, Australia (K.D.B.); and Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Canada (T.K., K.G.t.B.)
| | - Kartik D Bhatia
- From the Montreal Neurologic Institute and Hospital, Department of Diagnostic and Interventional Neuroradiology, McGill University Health Centre, 3801 Rue University, Montréal, QC, Canada H3A 2B4 (J.M.K.); Department of Medical Imaging, University of Toronto, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Division of Neuroradiology, Toronto Western Hospital, University Health Network, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Centre Hospitalier de l'Université de Montreal (CHUM), Department of Radiology, Service of Neuroradiology, l'Université de Montreal, Montréal, Canada (J.M.K.); Department of Materials Science & Engineering, Faculty of Applied Science & Engineering, University of Toronto, Toronto, Canada (D.V.); Department of Medical Imaging, Sydney Children's Hospitals Network, Westmead, Australia (K.D.B.); and Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Canada (T.K., K.G.t.B.)
| | - Hans G J Kortman
- From the Montreal Neurologic Institute and Hospital, Department of Diagnostic and Interventional Neuroradiology, McGill University Health Centre, 3801 Rue University, Montréal, QC, Canada H3A 2B4 (J.M.K.); Department of Medical Imaging, University of Toronto, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Division of Neuroradiology, Toronto Western Hospital, University Health Network, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Centre Hospitalier de l'Université de Montreal (CHUM), Department of Radiology, Service of Neuroradiology, l'Université de Montreal, Montréal, Canada (J.M.K.); Department of Materials Science & Engineering, Faculty of Applied Science & Engineering, University of Toronto, Toronto, Canada (D.V.); Department of Medical Imaging, Sydney Children's Hospitals Network, Westmead, Australia (K.D.B.); and Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Canada (T.K., K.G.t.B.)
| | - Timo Krings
- From the Montreal Neurologic Institute and Hospital, Department of Diagnostic and Interventional Neuroradiology, McGill University Health Centre, 3801 Rue University, Montréal, QC, Canada H3A 2B4 (J.M.K.); Department of Medical Imaging, University of Toronto, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Division of Neuroradiology, Toronto Western Hospital, University Health Network, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Centre Hospitalier de l'Université de Montreal (CHUM), Department of Radiology, Service of Neuroradiology, l'Université de Montreal, Montréal, Canada (J.M.K.); Department of Materials Science & Engineering, Faculty of Applied Science & Engineering, University of Toronto, Toronto, Canada (D.V.); Department of Medical Imaging, Sydney Children's Hospitals Network, Westmead, Australia (K.D.B.); and Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Canada (T.K., K.G.t.B.)
| | - Kieran P Murphy
- From the Montreal Neurologic Institute and Hospital, Department of Diagnostic and Interventional Neuroradiology, McGill University Health Centre, 3801 Rue University, Montréal, QC, Canada H3A 2B4 (J.M.K.); Department of Medical Imaging, University of Toronto, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Division of Neuroradiology, Toronto Western Hospital, University Health Network, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Centre Hospitalier de l'Université de Montreal (CHUM), Department of Radiology, Service of Neuroradiology, l'Université de Montreal, Montréal, Canada (J.M.K.); Department of Materials Science & Engineering, Faculty of Applied Science & Engineering, University of Toronto, Toronto, Canada (D.V.); Department of Medical Imaging, Sydney Children's Hospitals Network, Westmead, Australia (K.D.B.); and Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Canada (T.K., K.G.t.B.)
| | - Karel G terBrugge
- From the Montreal Neurologic Institute and Hospital, Department of Diagnostic and Interventional Neuroradiology, McGill University Health Centre, 3801 Rue University, Montréal, QC, Canada H3A 2B4 (J.M.K.); Department of Medical Imaging, University of Toronto, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Division of Neuroradiology, Toronto Western Hospital, University Health Network, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Centre Hospitalier de l'Université de Montreal (CHUM), Department of Radiology, Service of Neuroradiology, l'Université de Montreal, Montréal, Canada (J.M.K.); Department of Materials Science & Engineering, Faculty of Applied Science & Engineering, University of Toronto, Toronto, Canada (D.V.); Department of Medical Imaging, Sydney Children's Hospitals Network, Westmead, Australia (K.D.B.); and Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Canada (T.K., K.G.t.B.)
| | - David J Mikulis
- From the Montreal Neurologic Institute and Hospital, Department of Diagnostic and Interventional Neuroradiology, McGill University Health Centre, 3801 Rue University, Montréal, QC, Canada H3A 2B4 (J.M.K.); Department of Medical Imaging, University of Toronto, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Division of Neuroradiology, Toronto Western Hospital, University Health Network, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Centre Hospitalier de l'Université de Montreal (CHUM), Department of Radiology, Service of Neuroradiology, l'Université de Montreal, Montréal, Canada (J.M.K.); Department of Materials Science & Engineering, Faculty of Applied Science & Engineering, University of Toronto, Toronto, Canada (D.V.); Department of Medical Imaging, Sydney Children's Hospitals Network, Westmead, Australia (K.D.B.); and Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Canada (T.K., K.G.t.B.)
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22
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Raghunandan A, Ladron-de-Guevara A, Tithof J, Mestre H, Du T, Nedergaard M, Thomas JH, Kelley DH. Bulk flow of cerebrospinal fluid observed in periarterial spaces is not an artifact of injection. eLife 2021; 10:65958. [PMID: 33687330 PMCID: PMC7979157 DOI: 10.7554/elife.65958] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Accepted: 03/08/2021] [Indexed: 12/24/2022] Open
Abstract
Cerebrospinal fluid (CSF) flowing through periarterial spaces is integral to the brain’s mechanism for clearing metabolic waste products. Experiments that track tracer particles injected into the cisterna magna (CM) of mouse brains have shown evidence of pulsatile CSF flow in perivascular spaces surrounding pial arteries, with a bulk flow in the same direction as blood flow. However, the driving mechanism remains elusive. Several studies have suggested that the bulk flow might be an artifact, driven by the injection itself. Here, we address this hypothesis with new in vivo experiments where tracer particles are injected into the CM using a dual-syringe system, with simultaneous injection and withdrawal of equal amounts of fluid. This method produces no net increase in CSF volume and no significant increase in intracranial pressure. Yet, particle-tracking reveals flows that are consistent in all respects with the flows observed in earlier experiments with single-syringe injection.
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Affiliation(s)
- Aditya Raghunandan
- Department of Mechanical Engineering, University of Rochester, Rochester, United States
| | - Antonio Ladron-de-Guevara
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, United States
| | - Jeffrey Tithof
- Department of Mechanical Engineering, University of Rochester, Rochester, United States.,Department of Mechanical Engineering, University of Minnesota, Minneapolis, United States
| | - Humberto Mestre
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, United States
| | - Ting Du
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, United States
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, United States.,Center for Translational Neuromedicine, University of Copenhagen, Rochester, United States
| | - John H Thomas
- Department of Mechanical Engineering, University of Rochester, Rochester, United States
| | - Douglas H Kelley
- Department of Mechanical Engineering, University of Rochester, Rochester, United States
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23
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Natale G, Limanaqi F, Busceti CL, Mastroiacovo F, Nicoletti F, Puglisi-Allegra S, Fornai F. Glymphatic System as a Gateway to Connect Neurodegeneration From Periphery to CNS. Front Neurosci 2021; 15:639140. [PMID: 33633540 PMCID: PMC7900543 DOI: 10.3389/fnins.2021.639140] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 01/20/2021] [Indexed: 12/11/2022] Open
Abstract
The classic concept of the absence of lymphatic vessels in the central nervous system (CNS), suggesting the immune privilege of the brain in spite of its high metabolic rate, was predominant until recent times. On the other hand, this idea left questioned how cerebral interstitial fluid is cleared of waste products. It was generally thought that clearance depends on cerebrospinal fluid (CSF). Not long ago, an anatomically and functionally discrete paravascular space was revised to provide a pathway for the clearance of molecules drained within the interstitial space. According to this model, CSF enters the brain parenchyma along arterial paravascular spaces. Once mixed with interstitial fluid and solutes in a process mediated by aquaporin-4, CSF exits through the extracellular space along venous paravascular spaces, thus being removed from the brain. This process includes the participation of perivascular glial cells due to a sieving effect of their end-feet. Such draining space resembles the peripheral lymphatic system, therefore, the term "glymphatic" (glial-lymphatic) pathway has been coined. Specific studies focused on the potential role of the glymphatic pathway in healthy and pathological conditions, including neurodegenerative diseases. This mainly concerns Alzheimer's disease (AD), as well as hemorrhagic and ischemic neurovascular disorders; other acute degenerative processes, such as normal pressure hydrocephalus or traumatic brain injury are involved as well. Novel morphological and functional investigations also suggested alternative models to drain molecules through perivascular pathways, which enriched our insight of homeostatic processes within neural microenvironment. Under the light of these considerations, the present article aims to discuss recent findings and concepts on nervous lymphatic drainage and blood-brain barrier (BBB) in an attempt to understand how peripheral pathological conditions may be detrimental to the CNS, paving the way to neurodegeneration.
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Affiliation(s)
- Gianfranco Natale
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Fiona Limanaqi
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | | | | | | | | | - Francesco Fornai
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy.,IRCCS Neuromed, Pozzilli, Italy
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24
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Bryniarski MA, Ren T, Rizvi AR, Snyder AM, Morris ME. Targeting the Choroid Plexuses for Protein Drug Delivery. Pharmaceutics 2020; 12:pharmaceutics12100963. [PMID: 33066423 PMCID: PMC7602164 DOI: 10.3390/pharmaceutics12100963] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 10/05/2020] [Accepted: 10/10/2020] [Indexed: 12/15/2022] Open
Abstract
Delivery of therapeutic agents to the central nervous system is challenged by the barriers in place to regulate brain homeostasis. This is especially true for protein therapeutics. Targeting the barrier formed by the choroid plexuses at the interfaces of the systemic circulation and ventricular system may be a surrogate brain delivery strategy to circumvent the blood-brain barrier. Heterogenous cell populations located at the choroid plexuses provide diverse functions in regulating the exchange of material within the ventricular space. Receptor-mediated transcytosis may be a promising mechanism to deliver protein therapeutics across the tight junctions formed by choroid plexus epithelial cells. However, cerebrospinal fluid flow and other barriers formed by ependymal cells and perivascular spaces should also be considered for evaluation of protein therapeutic disposition. Various preclinical methods have been applied to delineate protein transport across the choroid plexuses, including imaging strategies, ventriculocisternal perfusions, and primary choroid plexus epithelial cell models. When used in combination with simultaneous measures of cerebrospinal fluid dynamics, they can yield important insight into pharmacokinetic properties within the brain. This review aims to provide an overview of the choroid plexuses and ventricular system to address their function as a barrier to pharmaceutical interventions and relevance for central nervous system drug delivery of protein therapeutics. Protein therapeutics targeting the ventricular system may provide new approaches in treating central nervous system diseases.
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25
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Naessens DMP, Coolen BF, de Vos J, VanBavel E, Strijkers GJ, Bakker ENTP. Altered brain fluid management in a rat model of arterial hypertension. Fluids Barriers CNS 2020; 17:41. [PMID: 32590994 PMCID: PMC7318739 DOI: 10.1186/s12987-020-00203-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 06/18/2020] [Indexed: 12/22/2022] Open
Abstract
Background Proper neuronal function is directly dependent on the composition, turnover, and amount of interstitial fluid that bathes the cells. Most of the interstitial fluid is likely to be derived from ion and water transport across the brain capillary endothelium, a process that may be altered in hypertension due to vascular pathologies as endothelial dysfunction and arterial remodelling. In the current study, we investigated the effects of hypertension on the brain for differences in the water homeostasis. Methods Magnetic resonance imaging (MRI) was performed on a 7T small animal MRI system on male spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY) of 10 months of age. The MRI protocol consisted of T2-weighted scans followed by quantitative apparent diffusion coefficient (ADC) mapping to measure volumes of different anatomical structures and water diffusion respectively. After MRI, we assessed the spatial distribution of aquaporin 4 expression around blood vessels. Results MRI analysis revealed a significant reduction in overall brain volume and remarkably higher cerebroventricular volume in SHR compared to WKY. Whole brain ADC, as well as ADC values of a number of specific anatomical structures, were significantly lower in hypertensive animals. Additionally, SHR exhibited higher brain parenchymal water content. Immunohistochemical analysis showed a profound expression of aquaporin 4 around blood vessels in both groups, with a significantly larger area of influence around arterioles. Evaluation of specific brain regions revealed a decrease in aquaporin 4 expression around capillaries in the corpus callosum of SHR. Conclusion These results indicate a shift in the brain water homeostasis of adult hypertensive rats.
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Affiliation(s)
- Daphne M P Naessens
- Department of Biomedical Engineering and Physics, Amsterdam Cardiovascular Sciences, Amsterdam Neuroscience, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands
| | - Bram F Coolen
- Department of Biomedical Engineering and Physics, Amsterdam Cardiovascular Sciences, Amsterdam Neuroscience, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands
| | - Judith de Vos
- Department of Biomedical Engineering and Physics, Amsterdam Cardiovascular Sciences, Amsterdam Neuroscience, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands
| | - Ed VanBavel
- Department of Biomedical Engineering and Physics, Amsterdam Cardiovascular Sciences, Amsterdam Neuroscience, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands
| | - Gustav J Strijkers
- Department of Biomedical Engineering and Physics, Amsterdam Cardiovascular Sciences, Amsterdam Neuroscience, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands
| | - Erik N T P Bakker
- Department of Biomedical Engineering and Physics, Amsterdam Cardiovascular Sciences, Amsterdam Neuroscience, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
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26
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Vinje V, Eklund A, Mardal KA, Rognes ME, Støverud KH. Intracranial pressure elevation alters CSF clearance pathways. Fluids Barriers CNS 2020; 17:29. [PMID: 32299464 PMCID: PMC7161287 DOI: 10.1186/s12987-020-00189-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 03/28/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Infusion testing is a common procedure to determine whether shunting will be beneficial in patients with normal pressure hydrocephalus. The method has a well-developed theoretical foundation and corresponding mathematical models that describe the CSF circulation from the choroid plexus to the arachnoid granulations. Here, we investigate to what extent the proposed glymphatic or paravascular pathway (or similar pathways) modifies the results of the traditional mathematical models. METHODS We used a compartment model to estimate pressure in the subarachnoid space and the paravascular spaces. For the arachnoid granulations, the cribriform plate and the glymphatic circulation, resistances were calculated and used to estimate pressure and flow before and during an infusion test. Finally, different variations to the model were tested to evaluate the sensitivity of selected parameters. RESULTS At baseline intracranial pressure (ICP), we found a very small paravascular flow directed into the subarachnoid space, while 60% of the fluid left through the arachnoid granulations and 40% left through the cribriform plate. However, during the infusion, 80% of the fluid left through the arachnoid granulations, 20% through the cribriform plate and flow in the PVS was stagnant. Resistance through the glymphatic system was computed to be 2.73 mmHg/(mL/min), considerably lower than other fluid pathways, giving non-realistic ICP during infusion if combined with a lymphatic drainage route. CONCLUSIONS The relative distribution of CSF flow to different clearance pathways depends on ICP, with the arachnoid granulations as the main contributor to outflow. As such, ICP increase is an important factor that should be addressed when determining the pathways of injected substances in the subarachnoid space. Our results suggest that the glymphatic resistance is too high to allow for pressure driven flow by arterial pulsations and at the same time too small to allow for a direct drainage route from PVS to cervical lymphatics.
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Affiliation(s)
- Vegard Vinje
- Department of Scientific Computing and Numerical Analysis, Simula Research Laboratory, Lysaker, Norway.
| | - Anders Eklund
- Department of Radiation Sciences, Umeå University, Umeå, Sweden
| | - Kent-Andre Mardal
- Department of Scientific Computing and Numerical Analysis, Simula Research Laboratory, Lysaker, Norway.,Department of Mathematics, University of Oslo, Oslo, Norway
| | - Marie E Rognes
- Department of Scientific Computing and Numerical Analysis, Simula Research Laboratory, Lysaker, Norway
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27
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Keep RF, Jones HC, Drewes LR. This was the year that was: brain barriers and brain fluid research in 2019. Fluids Barriers CNS 2020; 17:20. [PMID: 32138786 PMCID: PMC7059280 DOI: 10.1186/s12987-020-00181-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
This editorial highlights advances in brain barrier and brain fluid research published in 2019, as well as addressing current controversies and pressing needs. Topics include recent advances related to: the cerebral endothelium and the neurovascular unit; the choroid plexus, arachnoid membrane; cerebrospinal fluid and the glymphatic hypothesis; the impact of disease states on brain barriers and brain fluids; drug delivery to the brain; and translation of preclinical data to the clinic. This editorial also mourns the loss of two important figures in the field, Malcolm B. Segal and Edward G. Stopa.
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Affiliation(s)
- Richard F. Keep
- Department of Neurosurgery, University of Michigan, R5018 BSRB, 109 Zina Pitcher Place, Ann Arbor, MI 48109-2200 USA
| | | | - Lester R. Drewes
- Department of Biomedical Sciences, University of Minnesota Medical School Duluth, Duluth, MN 55812 USA
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28
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Vardakis JC, Bonfanti M, Franzetti G, Guo L, Lassila T, Mitolo M, Hoz de Vila M, Greenwood JP, Maritati G, Chou D, Taylor ZA, Venneri A, Homer-Vanniasinkam S, Balabani S, Frangi AF, Ventikos Y, Diaz-Zuccarini V. Highly integrated workflows for exploring cardiovascular conditions: Exemplars of precision medicine in Alzheimer's disease and aortic dissection. Morphologie 2019; 103:148-160. [PMID: 31786098 DOI: 10.1016/j.morpho.2019.10.045] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 10/12/2019] [Accepted: 10/16/2019] [Indexed: 12/31/2022]
Abstract
For precision medicine to be implemented through the lens of in silico technology, it is imperative that biophysical research workflows offer insight into treatments that are specific to a particular illness and to a particular subject. The boundaries of precision medicine can be extended using multiscale, biophysics-centred workflows that consider the fundamental underpinnings of the constituents of cells and tissues and their dynamic environments. Utilising numerical techniques that can capture the broad spectrum of biological flows within complex, deformable and permeable organs and tissues is of paramount importance when considering the core prerequisites of any state-of-the-art precision medicine pipeline. In this work, a succinct breakdown of two precision medicine pipelines developed within two Virtual Physiological Human (VPH) projects are given. The first workflow is targeted on the trajectory of Alzheimer's Disease, and caters for novel hypothesis testing through a multicompartmental poroelastic model which is integrated with a high throughput imaging workflow and subject-specific blood flow variability model. The second workflow gives rise to the patient specific exploration of Aortic Dissections via a multi-scale and compliant model, harnessing imaging, computational fluid-dynamics (CFD) and dynamic boundary conditions. Results relating to the first workflow include some core outputs of the multiporoelastic modelling framework, and the representation of peri-arterial swelling and peri-venous drainage solution fields. The latter solution fields were statistically analysed for a cohort of thirty-five subjects (stratified with respect to disease status, gender and activity level). The second workflow allowed for a better understanding of complex aortic dissection cases utilising both a rigid-wall model informed by minimal and clinically common datasets as well as a moving-wall model informed by rich datasets.
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Affiliation(s)
- J C Vardakis
- Centre for Computational Imaging & Simulation Technologies in Biomedicine (CISTIB), School of Computing, University of Leeds, UK.
| | - M Bonfanti
- Department of Mechanical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK; Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS), Department of Medical Physics and Biomedical Engineering, University College London, UK
| | - G Franzetti
- Department of Mechanical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK
| | - L Guo
- Department of Mechanical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK
| | - T Lassila
- Centre for Computational Imaging & Simulation Technologies in Biomedicine (CISTIB), School of Computing, University of Leeds, UK
| | - M Mitolo
- Functional MR Unit, Policlinico S. Orsola e Malpighi, Department of Biomedical and NeuroMotor Sciences (DiBiNeM), Bologna, Italy
| | - M Hoz de Vila
- Centre for Computational Imaging & Simulation Technologies in Biomedicine (CISTIB), School of Computing, University of Leeds, UK
| | - J P Greenwood
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, UK; Leeds Teaching Hospitals NHS Trust, Leeds, UK
| | - G Maritati
- Ospedale A. Perrino, Brindisi, Italy; Azienda Ospedaliera San Camillo-Forlanini, Rome, Italy
| | - D Chou
- Department of Mechanical Engineering, National Central University, Taoyuan County, Taiwan
| | - Z A Taylor
- Centre for Computational Imaging & Simulation Technologies in Biomedicine (CISTIB), School of Mechanical Engineering, University of Leeds, UK
| | - A Venneri
- Department of Neuroscience, Medical School, University of Sheffield, UK
| | - S Homer-Vanniasinkam
- Department of Mechanical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK; Leeds Teaching Hospitals NHS Trust, Leeds, UK; University of Warwick Medical School & University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK
| | - S Balabani
- Department of Mechanical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK
| | - A F Frangi
- Centre for Computational Imaging & Simulation Technologies in Biomedicine (CISTIB), School of Computing, University of Leeds, UK
| | - Y Ventikos
- Department of Mechanical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK
| | - V Diaz-Zuccarini
- Department of Mechanical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK; Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS), Department of Medical Physics and Biomedical Engineering, University College London, UK.
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29
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Martinac AD, Bilston LE. Computational modelling of fluid and solute transport in the brain. Biomech Model Mechanobiol 2019; 19:781-800. [DOI: 10.1007/s10237-019-01253-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 11/05/2019] [Indexed: 01/10/2023]
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30
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Uncertainty quantification of parenchymal tracer distribution using random diffusion and convective velocity fields. Fluids Barriers CNS 2019; 16:32. [PMID: 31564250 PMCID: PMC6767654 DOI: 10.1186/s12987-019-0152-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 09/07/2019] [Indexed: 11/28/2022] Open
Abstract
Background Influx and clearance of substances in the brain parenchyma occur by a combination of diffusion and convection, but the relative importance of these mechanisms is unclear. Accurate modeling of tracer distributions in the brain relies on parameters that are partially unknown and with literature values varying by several orders of magnitude. In this work, we rigorously quantified the variability of tracer distribution in the brain resulting from uncertainty in diffusion and convection model parameters. Methods Using the convection–diffusion–reaction equation, we simulated tracer distribution in the brain parenchyma after intrathecal injection. Several models were tested to assess the uncertainty both in type of diffusion and velocity fields and also the importance of their magnitude. Our results were compared with experimental MRI results of tracer enhancement. Results In models of pure diffusion, the expected amount of tracer in the gray matter reached peak value after 15 h, while the white matter did not reach peak within 24 h with high likelihood. Models of the glymphatic system were similar qualitatively to the models of pure diffusion with respect to expected time to peak but displayed less variability. However, the expected time to peak was reduced to 11 h when an additional directionality was prescribed for the glymphatic circulation. In a model including drainage directly from the brain parenchyma, time to peak occured after 6–8 h for the gray matter. Conclusion Even when uncertainties are taken into account, we find that diffusion alone is not sufficient to explain transport of tracer deep into the white matter as seen in experimental data. A glymphatic velocity field may increase transport if a large-scale directional structure is included in the glymphatic circulation.
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31
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Matchkov VV. Vascular microdomain signalling and possible novel treatments in cardiovascular diseases. Exp Physiol 2019; 104:1011-1012. [PMID: 31257686 DOI: 10.1113/ep087819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 05/14/2019] [Indexed: 11/08/2022]
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32
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Abstract
New Findings What is the topic of this review? In this symposium report, we review the glymphatic clearance from the brain. What advances does it highlight? Evaluation of the evidence indicates that cerebrospinal fluid flows along paravascular spaces at the surface of the brain. However, bulk flow along penetrating arteries into the brain, followed by exit along veins, requires further confirmation. Clearance from the brain, based on mixing, might provide an alternative explanation for experimental findings.
Abstract The interstitial fluid of the brain provides the environment for proper neuronal function. Maintenance of the volume and composition of interstitial fluid requires regulation of the influx and removal of water, ions, nutritive and waste products. The recently described glymphatic pathway might contribute to some of these functions. It is proposed that cerebrospinal fluid enters the brain via paravascular spaces along arteries, mixes with interstitial fluid, and leaves the brain via paravascular spaces along veins. In this symposium report, we review the glymphatic concept, its concerns, and alternative views on interstitial fluid–cerebrospinal fluid exchange.
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Affiliation(s)
- Erik N T P Bakker
- Amsterdam UMC, University of Amsterdam, Department of Biomedical Engineering and Physics, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | - Daphne M P Naessens
- Amsterdam UMC, University of Amsterdam, Department of Biomedical Engineering and Physics, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | - Ed VanBavel
- Amsterdam UMC, University of Amsterdam, Department of Biomedical Engineering and Physics, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
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