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Bagheri M, Habibzadeh S, Moeini M. Transient Changes in Cerebral Tissue Oxygen, Glucose, and Temperature by Microstrokes: A Computational Study. Microcirculation 2024; 31:e12872. [PMID: 38944839 DOI: 10.1111/micc.12872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2024] [Revised: 05/09/2024] [Accepted: 06/08/2024] [Indexed: 07/02/2024]
Abstract
OBJECTIVE This study focuses on evaluating the disruptions in key physiological parameters during microstroke events to assess their severity. METHODS A mathematical model was developed to simulate the changes in cerebral tissue pO2, glucose concentration, and temperature due to blood flow interruptions. The model considers variations in baseline cerebral blood flow (CBF), capillary density, and blood oxygen/glucose levels, as well as ambient temperature changes. RESULTS Simulations indicate that complete blood flow obstruction still allows for limited glucose availability, supporting nonoxidative metabolism and potentially exacerbating lactate buildup and acidosis. Partial obstructions decrease tissue pO2, with minimal impact on glucose level, which can remain almost unchanged or even slightly increase. Reduced CBF, capillary density, or blood oxygen due to aging or disease enhances hypoxia risk at lower obstruction levels, with capillary density having a significant effect on stroke severity by influencing both pO2 and glucose levels. Conditions could lead to co-occurrence of hypoxia/hypoglycemia or hypoxia/hyperglycemia, each worsening outcomes. Temperature effects were minimal in deep brain regions but varied near the skull by 0.2-0.8°C depending on ambient temperature. CONCLUSIONS The model provides insights into the conditions driving severe stroke outcomes based on estimated levels of hypoxia, hypoglycemia, hyperglycemia, and temperature changes.
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Affiliation(s)
- Marzieh Bagheri
- Department of Chemical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran
| | - Sajjad Habibzadeh
- Department of Chemical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran
| | - Mohammad Moeini
- Department of Biomedical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran
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2
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Jamshidi M, Ventimiglia T, Sudres P, Zhang C, Lesage F, Rooney W, Schwartz D, Linninger AA. Impact of stalling events on microcirculatory hemodynamics in the aged brain. Microcirculation 2024; 31:e12845. [PMID: 38265175 PMCID: PMC11014774 DOI: 10.1111/micc.12845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 12/11/2023] [Accepted: 01/05/2024] [Indexed: 01/25/2024]
Abstract
OBJECTIVE The role of cerebral microvasculature in cognitive dysfunction can be investigated by identifying the impact of blood flow on cortical tissue oxygenation. In this paper, the impact of capillary stalls on microcirculatory characteristics such as flow and hematocrit (Ht) in the cortical angioarchitecture is studied. METHODS Using a deterministic mathematical model to simulate blood flow in a realistic mouse cortex, hemodynamics parameters, including pressure, flow, vessel diameter-adjustable hematocrit, and transit time are calculated as a function of stalling events. RESULTS Using a non-linear plasma skimming model, it is observed that Ht increases in the penetrating arteries from the pial vessels as a function of cortical depth. The incidence of stalling on Ht distribution along the blood network vessels shows reduction of RBCs around the tissue near occlusion sites and decreased Ht concentration downstream from the blockage points. Moreover, upstream of the occlusion, there is a noticeable increase of the Ht, leading to larger flow resistance due to higher blood viscosity. We predicted marked changes in transit time behavior due to stalls which match trends observed in mice in vivo. CONCLUSIONS These changes to blood cell quantity and quality may be implicated in the development of Alzheimer's disease and contribute to the course of the illness.
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Affiliation(s)
- Mohammad Jamshidi
- Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Thomas Ventimiglia
- Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Patrice Sudres
- Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Cong Zhang
- Department of Electrical Engineering, Polytechnique Montréal, Montreal, Canada
| | - Frederic Lesage
- Department of Electrical Engineering, Polytechnique Montréal, Montreal, Canada
| | - William Rooney
- Advanced Imaging Research Center, Oregon Health & Science University, Portland, Oregon, USA
| | - Daniel Schwartz
- Advanced Imaging Research Center, Oregon Health & Science University, Portland, Oregon, USA
| | - Andreas A Linninger
- Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, Illinois, USA
- Department of Neurosurgery, University of Illinois at Chicago, Chicago, Illinois, USA
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3
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Maung Ye SS, Phng LK. A cell-and-plasma numerical model reveals hemodynamic stress and flow adaptation in zebrafish microvessels after morphological alteration. PLoS Comput Biol 2023; 19:e1011665. [PMID: 38048371 PMCID: PMC10721208 DOI: 10.1371/journal.pcbi.1011665] [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: 05/23/2023] [Revised: 12/14/2023] [Accepted: 11/06/2023] [Indexed: 12/06/2023] Open
Abstract
The development of a functional cardiovascular system ensures a sustainable oxygen, nutrient and hormone delivery system for successful embryonic development and homeostasis in adulthood. While early vessels are formed by biochemical signaling and genetic programming, the onset of blood flow provides mechanical cues that participate in vascular remodeling of the embryonic vascular system. The zebrafish is a prolific animal model for studying the quantitative relationship between blood flow and vascular morphogenesis due to a combination of favorable factors including blood flow visualization in optically transparent larvae. In this study, we have developed a cell-and-plasma blood transport model using computational fluid dynamics (CFD) to understand how red blood cell (RBC) partitioning affect lumen wall shear stress (WSS) and blood pressure in zebrafish trunk blood vascular networks with altered rheology and morphology. By performing live imaging of embryos with reduced hematocrit, we discovered that cardiac output and caudal artery flow rates were maintained. These adaptation trends were recapitulated in our CFD models, which showed reduction in network WSS via viscosity reduction in the caudal artery/vein and via pressure gradient weakening in the intersegmental vessels (ISVs). Embryos with experimentally reduced lumen diameter showed reduced cardiac output and caudal artery flow rate. Factoring in this trend into our CFD models, simulations highlighted that lumen diameter reduction increased vessel WSS but this increase was mitigated by flow reduction due to the adaptive network pressure gradient weakening. Additionally, hypothetical network CFD models with different vessel lumen diameter distribution characteristics indicated the significance of axial variation in lumen diameter and cross-sectional shape for establishing physiological WSS gradients along ISVs. In summary, our work demonstrates how both experiment-driven and hypothetical CFD modeling can be employed for the study of blood flow physiology during vascular remodeling.
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Affiliation(s)
- Swe Soe Maung Ye
- Laboratory for Vascular Morphogenesis, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe, Japan
| | - Li-Kun Phng
- Laboratory for Vascular Morphogenesis, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe, Japan
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4
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Delafontaine-Martel P, Zhang C, Lu X, Damseh R, Lesage F, Marchand PJ. Targeted capillary photothrombosis via multiphoton excitation of Rose Bengal. J Cereb Blood Flow Metab 2023; 43:1713-1725. [PMID: 36647768 PMCID: PMC10581236 DOI: 10.1177/0271678x231151560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 12/12/2022] [Accepted: 12/19/2022] [Indexed: 01/18/2023]
Abstract
Microvascular stalling, the process occurring when a capillary temporarily loses perfusion, has gained increasing interest in recent years through its demonstrated presence in various neuropathologies. Studying the impact of such stalls on the surrounding brain tissue is of paramount importance to understand their role in such diseases. Despite efforts trying to study the stalling events, investigations are hampered by their elusiveness and scarcity. In an attempt to alleviate these hurdles, we present here a novel methodology enabling transient occlusions of targeted microvascular segments through multiphoton excitation of Rose Bengal, an established photothrombotic agent. With n = 7 mice C57BL/6 J (5 males and 2 females) and 95 photothrombosis trials, we demonstrate the ability of triggering reversible blockages by illuminating a capillary segment during ∼300 s at 1000 nm, using a standard Ti:Sapphire femtosecond laser. Furthermore, we performed concurrent Optical Coherence Microscopy (OCM) angiography imaging of the microvascular network to highlight the specificity of the targeted occlusion and its duration. Through comparison with a control group, we conclude that blood flow cessation is indeed created by the photothrombotic agent via multiphoton excitation and is temporary, followed by a flow recovery in less than 24 h. Moreover, Immunohistology points toward a stalling mechanism driven by adherence of the neutrophil in the vascular lumen. This observation seems to be promoted by the inflammation locally created via multiphoton activation of Rose Bengal.
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Affiliation(s)
- Patrick Delafontaine-Martel
- Department of Electrical Engineering, Polytechnique Montreal, Montreal, Canada
- Research Center, Montreal Heart Institute, Montreal, Canada
| | - Cong Zhang
- Department of Electrical Engineering, Polytechnique Montreal, Montreal, Canada
- Research Center, Montreal Heart Institute, Montreal, Canada
| | - Xuecong Lu
- Research Center, Montreal Heart Institute, Montreal, Canada
- DeGroote School of Business – McMaster University, Ontario, Canada
| | - Rafat Damseh
- Research Center, Montreal Heart Institute, Montreal, Canada
- College of Information Technology, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Frédéric Lesage
- Department of Electrical Engineering, Polytechnique Montreal, Montreal, Canada
- Research Center, Montreal Heart Institute, Montreal, Canada
| | - Paul J Marchand
- Department of Electrical Engineering, Polytechnique Montreal, Montreal, Canada
- Research Center, Montreal Heart Institute, Montreal, Canada
- École polytechnique fédérale de Lausanne- EPFL, Lausanne, Switzerland
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Epp R, Glück C, Binder NF, El Amki M, Weber B, Wegener S, Jenny P, Schmid F. The role of leptomeningeal collaterals in redistributing blood flow during stroke. PLoS Comput Biol 2023; 19:e1011496. [PMID: 37871109 PMCID: PMC10621965 DOI: 10.1371/journal.pcbi.1011496] [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: 12/30/2022] [Revised: 11/02/2023] [Accepted: 09/03/2023] [Indexed: 10/25/2023] Open
Abstract
Leptomeningeal collaterals (LMCs) connect the main cerebral arteries and provide alternative pathways for blood flow during ischaemic stroke. This is beneficial for reducing infarct size and reperfusion success after treatment. However, a better understanding of how LMCs affect blood flow distribution is indispensable to improve therapeutic strategies. Here, we present a novel in silico approach that incorporates case-specific in vivo data into a computational model to simulate blood flow in large semi-realistic microvascular networks from two different mouse strains, characterised by having many and almost no LMCs between middle and anterior cerebral artery (MCA, ACA) territories. This framework is unique because our simulations are directly aligned with in vivo data. Moreover, it allows us to analyse perfusion characteristics quantitatively across all vessel types and for networks with no, few and many LMCs. We show that the occlusion of the MCA directly caused a redistribution of blood that was characterised by increased flow in LMCs. Interestingly, the improved perfusion of MCA-sided microvessels after dilating LMCs came at the cost of a reduced blood supply in other brain areas. This effect was enhanced in regions close to the watershed line and when the number of LMCs was increased. Additional dilations of surface and penetrating arteries after stroke improved perfusion across the entire vasculature and partially recovered flow in the obstructed region, especially in networks with many LMCs, which further underlines the role of LMCs during stroke.
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Affiliation(s)
- Robert Epp
- Institute of Fluid Dynamics, ETH Zurich, Zurich, Switzerland
| | - Chaim Glück
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Nadine Felizitas Binder
- Deptartment of Neurology, University Hospital Zurich and University of Zurich, Zurich, Switzerland
| | - Mohamad El Amki
- Deptartment of Neurology, University Hospital Zurich and University of Zurich, Zurich, Switzerland
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Susanne Wegener
- Deptartment of Neurology, University Hospital Zurich and University of Zurich, Zurich, Switzerland
| | - Patrick Jenny
- Institute of Fluid Dynamics, ETH Zurich, Zurich, Switzerland
| | - Franca Schmid
- Institute of Fluid Dynamics, ETH Zurich, Zurich, Switzerland
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
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6
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Travasso RDM, Coelho-Santos V. Image-based angio-adaptation modelling: a playground to study cerebrovascular development. Front Physiol 2023; 14:1223308. [PMID: 37565149 PMCID: PMC10411953 DOI: 10.3389/fphys.2023.1223308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 07/12/2023] [Indexed: 08/12/2023] Open
Affiliation(s)
- Rui D. M. Travasso
- Department of Physics, Center for Physics of the University of Coimbra (CFisUC), University of Coimbra, Coimbra, Portugal
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, Coimbra, Portugal
| | - Vanessa Coelho-Santos
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, Coimbra, Portugal
- Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Coimbra, Portugal
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Giblin J, Kura S, Nunuez JLU, Zhang J, Kureli G, Jiang J, Boas DA, Chen IA. High throughput detection of capillary stalling events with Bessel beam two-photon microscopy. NEUROPHOTONICS 2023; 10:035009. [PMID: 37705938 PMCID: PMC10495839 DOI: 10.1117/1.nph.10.3.035009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 08/09/2023] [Accepted: 08/17/2023] [Indexed: 09/15/2023]
Abstract
Significance Brief disruptions in capillary flow, commonly referred to as capillary "stalling," have gained interest recently for their potential role in disrupting cerebral blood flow and oxygen delivery. Approaches to studying this phenomenon have been hindered by limited volumetric imaging rates and cumbersome manual analysis. The ability to precisely and efficiently quantify the dynamics of these events will be key in understanding their potential role in stroke and neurodegenerative diseases, such as Alzheimer's disease. Aim Our study aimed to demonstrate that the fast volumetric imaging rates offered by Bessel beam two-photon microscopy combined with improved data analysis throughput allows for faster and more precise measurement of capillary stall dynamics. Results We found that while our analysis approach was unable to achieve full automation, we were able to cut analysis time in half while also finding stalling events that were missed in traditional blind manual analysis. The resulting data showed that our Bessel beam system was captured more stalling events compared to optical coherence tomography, particularly shorter stalling events. We then compare differences in stall dynamics between a young and old group of mice as well as a demonstrate changes in stalling before and after photothrombotic model of stroke. Finally, we also demonstrate the ability to monitor arteriole dynamics alongside stall dynamics. Conclusions Bessel beam two-photon microscopy combined with high throughput analysis is a powerful tool for studying capillary stalling due to its ability to monitor hundreds of capillaries simultaneously at high frame rates.
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Affiliation(s)
- John Giblin
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Boston University, Neurophotonics Center, Boston, Massachusetts, United States
| | - Sreekanth Kura
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Boston University, Neurophotonics Center, Boston, Massachusetts, United States
| | - Juan Luis Ugarte Nunuez
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Boston University, Neurophotonics Center, Boston, Massachusetts, United States
| | - Juncheng Zhang
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Boston University, Neurophotonics Center, Boston, Massachusetts, United States
| | - Gulce Kureli
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Boston University, Neurophotonics Center, Boston, Massachusetts, United States
| | - John Jiang
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Boston University, Neurophotonics Center, Boston, Massachusetts, United States
| | - David A. Boas
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Boston University, Neurophotonics Center, Boston, Massachusetts, United States
| | - Ichun A. Chen
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Boston University, Neurophotonics Center, Boston, Massachusetts, United States
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8
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Zhu L, Wang M, Liu Y, Fu P, Zhang W, Zhang H, Roe AW, Xi W. Single-microvessel occlusion produces lamina-specific microvascular flow vasodynamics and signs of neurodegenerative change. Cell Rep 2023; 42:112469. [PMID: 37141094 DOI: 10.1016/j.celrep.2023.112469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 01/12/2023] [Accepted: 04/18/2023] [Indexed: 05/05/2023] Open
Abstract
Recent studies have highlighted the importance of understanding the architecture and function of microvasculature, and dysfunction of these microvessels may underlie neurodegenerative disease. Here, we utilize a high-precision ultrafast laser-induced photothrombosis (PLP) method to occlude single capillaries and then quantitatively study the effects on vasodynamics and surrounding neurons. Analysis of the microvascular architecture and hemodynamics after single-capillary occlusion reveals distinct changes upstream vs. downstream branches, which shows rapid regional flow redistribution and local downstream blood-brain barrier (BBB) leakage. Focal ischemia via capillary occlusions surrounding labeled target neurons induces dramatic and rapid lamina-specific changes in neuronal dendritic architecture. Further, we find that micro-occlusion at two different depths within the same vascular arbor results in distinct effects on flow profiles in layers 2/3 vs layer 4. The current results reveal laminar-scale regulation distinctions in microinfarct response and raise the possibility that relatively greater impacts on microvascular function contribute to cognitive decline in neurodegenerative disease.
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Affiliation(s)
- Liang Zhu
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310020, China; Interdisciplinary Institute of Neuroscience and Technology (ZIINT), College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou 310027, China
| | - Mengqi Wang
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310020, China
| | - Yin Liu
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310020, China
| | - Peng Fu
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310020, China
| | - Weijie Zhang
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou 310027, China
| | - Hequn Zhang
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310020, China
| | - Anna Wang Roe
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310020, China; MOE Frontier Science Center for Brain Research and Brain Machine Integration, Zhejiang University, Hangzhou 310058, China; Key Laboratory of Biomedical Engineering of the Ministry of Education, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou 310027, China.
| | - Wang Xi
- Interdisciplinary Institute of Neuroscience and Technology (ZIINT), The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310020, China; MOE Frontier Science Center for Brain Research and Brain Machine Integration, Zhejiang University, Hangzhou 310058, China; Key Laboratory of Biomedical Engineering of the Ministry of Education, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou 310027, China.
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9
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Schreiber S, Bernal J, Arndt P, Schreiber F, Müller P, Morton L, Braun-Dullaeus RC, Valdés-Hernández MDC, Duarte R, Wardlaw JM, Meuth SG, Mietzner G, Vielhaber S, Dunay IR, Dityatev A, Jandke S, Mattern H. Brain Vascular Health in ALS Is Mediated through Motor Cortex Microvascular Integrity. Cells 2023; 12:957. [PMID: 36980297 PMCID: PMC10047140 DOI: 10.3390/cells12060957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 03/07/2023] [Accepted: 03/15/2023] [Indexed: 03/30/2023] Open
Abstract
Brain vascular health appears to be critical for preventing the development of amyotrophic lateral sclerosis (ALS) and slowing its progression. ALS patients often demonstrate cardiovascular risk factors and commonly suffer from cerebrovascular disease, with evidence of pathological alterations in their small cerebral blood vessels. Impaired vascular brain health has detrimental effects on motor neurons: vascular endothelial growth factor levels are lowered in ALS, which can compromise endothelial cell formation and the integrity of the blood-brain barrier. Increased turnover of neurovascular unit cells precedes their senescence, which, together with pericyte alterations, further fosters the failure of toxic metabolite removal. We here provide a comprehensive overview of the pathogenesis of impaired brain vascular health in ALS and how novel magnetic resonance imaging techniques can aid its detection. In particular, we discuss vascular patterns of blood supply to the motor cortex with the number of branches from the anterior and middle cerebral arteries acting as a novel marker of resistance and resilience against downstream effects of vascular risk and events in ALS. We outline how certain interventions adapted to patient needs and capabilities have the potential to mechanistically target the brain microvasculature towards favorable motor cortex blood supply patterns. Through this strategy, we aim to guide novel approaches to ALS management and a better understanding of ALS pathophysiology.
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Affiliation(s)
- Stefanie Schreiber
- Department of Neurology, Otto von Guericke University Magdeburg, Medical Faculty, 39120 Magdeburg, Germany
- German Center for Neurodegenerative Diseases (DZNE) within the Helmholtz Association, 39120 Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), 39106 Magdeburg, Germany
| | - Jose Bernal
- Department of Neurology, Otto von Guericke University Magdeburg, Medical Faculty, 39120 Magdeburg, Germany
- German Center for Neurodegenerative Diseases (DZNE) within the Helmholtz Association, 39120 Magdeburg, Germany
| | - Philipp Arndt
- Department of Neurology, Otto von Guericke University Magdeburg, Medical Faculty, 39120 Magdeburg, Germany
- German Center for Neurodegenerative Diseases (DZNE) within the Helmholtz Association, 39120 Magdeburg, Germany
| | - Frank Schreiber
- Department of Neurology, Otto von Guericke University Magdeburg, Medical Faculty, 39120 Magdeburg, Germany
- German Center for Neurodegenerative Diseases (DZNE) within the Helmholtz Association, 39120 Magdeburg, Germany
| | - Patrick Müller
- German Center for Neurodegenerative Diseases (DZNE) within the Helmholtz Association, 39120 Magdeburg, Germany
- Department of Internal Medicine/Cardiology and Angiology, Otto von Guericke University Magdeburg, 39120 Magdeburg, Germany
| | - Lorena Morton
- Institute of Inflammation and Neurodegeneration, Otto von Guericke University Magdeburg, 39120 Magdeburg, Germany
| | | | | | - Roberto Duarte
- Centre for Clinical Brain Sciences, The University of Edinburgh, UK Dementia Research Institute Centre, Edinburgh EH16 4UX, UK
| | - Joanna Marguerite Wardlaw
- Centre for Clinical Brain Sciences, The University of Edinburgh, UK Dementia Research Institute Centre, Edinburgh EH16 4UX, UK
| | - Sven Günther Meuth
- Department of Neurology, Medical Faculty, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Grazia Mietzner
- Department of Neurology, Otto von Guericke University Magdeburg, Medical Faculty, 39120 Magdeburg, Germany
| | - Stefan Vielhaber
- Department of Neurology, Otto von Guericke University Magdeburg, Medical Faculty, 39120 Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), 39106 Magdeburg, Germany
| | - Ildiko Rita Dunay
- Center for Behavioral Brain Sciences (CBBS), 39106 Magdeburg, Germany
- Institute of Inflammation and Neurodegeneration, Otto von Guericke University Magdeburg, 39120 Magdeburg, Germany
| | - Alexander Dityatev
- German Center for Neurodegenerative Diseases (DZNE) within the Helmholtz Association, 39120 Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), 39106 Magdeburg, Germany
- Medical Faculty, Otto von Guericke University, 39120 Magdeburg, Germany
| | - Solveig Jandke
- Department of Neurology, Otto von Guericke University Magdeburg, Medical Faculty, 39120 Magdeburg, Germany
- German Center for Neurodegenerative Diseases (DZNE) within the Helmholtz Association, 39120 Magdeburg, Germany
| | - Hendrik Mattern
- German Center for Neurodegenerative Diseases (DZNE) within the Helmholtz Association, 39120 Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), 39106 Magdeburg, Germany
- Department of Biomedical Magnetic Resonance, Faculty of Natural Sciences, Otto von Guericke University Magdeburg, 39120 Magdeburg, Germany
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10
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Zhou Q, Schirrmann K, Doman E, Chen Q, Singh N, Selvaganapathy PR, Bernabeu MO, Jensen OE, Juel A, Chernyavsky IL, Krüger T. Red blood cell dynamics in extravascular biological tissues modelled as canonical disordered porous media. Interface Focus 2022; 12:20220037. [PMID: 36325194 PMCID: PMC9560785 DOI: 10.1098/rsfs.2022.0037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 09/07/2022] [Indexed: 12/17/2022] Open
Abstract
The dynamics of blood flow in the smallest vessels and passages of the human body, where the cellular character of blood becomes prominent, plays a dominant role in the transport and exchange of solutes. Recent studies have revealed that the microhaemodynamics of a vascular network is underpinned by its interconnected structure, and certain structural alterations such as capillary dilation and blockage can substantially change blood flow patterns. However, for extravascular media with disordered microstructure (e.g. the porous intervillous space in the placenta), it remains unclear how the medium's structure affects the haemodynamics. Here, we simulate cellular blood flow in simple models of canonical porous media representative of extravascular biological tissue, with corroborative microfluidic experiments performed for validation purposes. For the media considered here, we observe three main effects: first, the relative apparent viscosity of blood increases with the structural disorder of the medium; second, the presence of red blood cells (RBCs) dynamically alters the flow distribution in the medium; third, symmetry breaking introduced by moderate structural disorder can promote more homogeneous distribution of RBCs. Our findings contribute to a better understanding of the cell-scale haemodynamics that mediates the relationship linking the function of certain biological tissues to their microstructure.
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Affiliation(s)
- Qi Zhou
- School of Engineering, Institute for Multiscale Thermofluids, Edinburgh, UK
| | - Kerstin Schirrmann
- Manchester Centre for Nonlinear Dynamics, Manchester, UK
- Department of Physics and Astronomy, The University of Manchester, Manchester, UK
| | - Eleanor Doman
- Department of Mathematics, The University of Manchester, Manchester, UK
| | - Qi Chen
- Manchester Centre for Nonlinear Dynamics, Manchester, UK
- Department of Physics and Astronomy, The University of Manchester, Manchester, UK
| | - Naval Singh
- Manchester Centre for Nonlinear Dynamics, Manchester, UK
- Department of Physics and Astronomy, The University of Manchester, Manchester, UK
| | - P. Ravi Selvaganapathy
- Department of Mechanical Engineering, School of Biomedical Engineering, McMaster University, Hamilton, Canada
| | - Miguel O. Bernabeu
- Centre for Medical Informatics, The University of Edinburgh, Edinburgh, UK
- The Bayes Centre, The University of Edinburgh, Edinburgh, UK
| | - Oliver E. Jensen
- Department of Mathematics, The University of Manchester, Manchester, UK
| | - Anne Juel
- Manchester Centre for Nonlinear Dynamics, Manchester, UK
- Department of Physics and Astronomy, The University of Manchester, Manchester, UK
| | - Igor L. Chernyavsky
- Department of Mathematics, The University of Manchester, Manchester, UK
- Maternal and Fetal Health Research Centre, School of Medical Sciences, The University of Manchester, Manchester, UK
| | - Timm Krüger
- School of Engineering, Institute for Multiscale Thermofluids, Edinburgh, UK
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Berthiaume AA, Schmid F, Stamenkovic S, Coelho-Santos V, Nielson CD, Weber B, Majesky MW, Shih AY. Pericyte remodeling is deficient in the aged brain and contributes to impaired capillary flow and structure. Nat Commun 2022; 13:5912. [PMID: 36207315 PMCID: PMC9547063 DOI: 10.1038/s41467-022-33464-w] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 09/14/2022] [Indexed: 02/06/2023] Open
Abstract
Deterioration of brain capillary flow and architecture is a hallmark of aging and dementia. It remains unclear how loss of brain pericytes in these conditions contributes to capillary dysfunction. Here, we conduct cause-and-effect studies by optically ablating pericytes in adult and aged mice in vivo. Focal pericyte loss induces capillary dilation without blood-brain barrier disruption. These abnormal dilations are exacerbated in the aged brain, and result in increased flow heterogeneity in capillary networks. A subset of affected capillaries experience reduced perfusion due to flow steal. Some capillaries stall in flow and regress, leading to loss of capillary connectivity. Remodeling of neighboring pericytes restores endothelial coverage and vascular tone within days. Pericyte remodeling is slower in the aged brain, resulting in regions of persistent capillary dilation. These findings link pericyte loss to disruption of capillary flow and structure. They also identify pericyte remodeling as a therapeutic target to preserve capillary flow dynamics.
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Affiliation(s)
- Andrée-Anne Berthiaume
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA, USA
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA
| | - Franca Schmid
- Institute of Fluid Dynamics, ETH Zurich, Sonneggstrasse 3, Zurich, Switzerland
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, Zurich, Switzerland
| | - Stefan Stamenkovic
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA, USA
| | - Vanessa Coelho-Santos
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA, USA
| | - Cara D Nielson
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA, USA
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, USA
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, Zurich, Switzerland
- Neuroscience Center Zurich, University and ETH Zurich, Winterthurerstrasse 190, Zurich, Switzerland
| | - Mark W Majesky
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA, USA
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA
| | - Andy Y Shih
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA, USA.
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA.
- Department of Pediatrics, University of Washington, Seattle, WA, USA.
- Department of Bioengineering, University of Washington, Seattle, WA, USA.
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12
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Xue Y, Georgakopoulou T, van der Wijk AE, Józsa TI, van Bavel E, Payne SJ. Quantification of hypoxic regions distant from occlusions in cerebral penetrating arteriole trees. PLoS Comput Biol 2022; 18:e1010166. [PMID: 35930591 PMCID: PMC9385041 DOI: 10.1371/journal.pcbi.1010166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 08/17/2022] [Accepted: 07/14/2022] [Indexed: 11/18/2022] Open
Abstract
The microvasculature plays a key role in oxygen transport in the mammalian brain. Despite the close coupling between cerebral vascular geometry and local oxygen demand, recent experiments have reported that microvascular occlusions can lead to unexpected distant tissue hypoxia and infarction. To better understand the spatial correlation between the hypoxic regions and the occlusion sites, we used both in vivo experiments and in silico simulations to investigate the effects of occlusions in cerebral penetrating arteriole trees on tissue hypoxia. In a rat model of microembolisation, 25 μm microspheres were injected through the carotid artery to occlude penetrating arterioles. In representative models of human cortical columns, the penetrating arterioles were occluded by simulating the transport of microspheres of the same size and the oxygen transport was simulated using a Green’s function method. The locations of microspheres and hypoxic regions were segmented, and two novel distance analyses were implemented to study their spatial correlation. The distant hypoxic regions were found to be present in both experiments and simulations, and mainly due to the hypoperfusion in the region downstream of the occlusion site. Furthermore, a reasonable agreement for the spatial correlation between hypoxic regions and occlusion sites is shown between experiments and simulations, which indicates the good applicability of in silico models in understanding the response of cerebral blood flow and oxygen transport to microemboli. The brain function depends on the continuous oxygen supply through the bloodstream inside the microvasculature. Occlusions in the microvascular network will disturb the oxygen delivery in the brain and result in hypoxic tissues that can lead to infarction and cognitive dysfunction. To aid in understanding the formation of hypoxic tissues caused by micro-occlusions in the penetrating arteriole trees, we use rodent experiments and simulations of human vascular networks to study the spatial correlations between the hypoxic regions and the occlusion locations. Our results suggest that hypoxic regions can form distally from the occlusion site, which agrees with the previous observations in the rat brain. These distant hypoxic regions are primarily due to the lack of blood flow in the brain tissues downstream of the occlusion. Moreover, a reasonable agreement of the spatial relationship is found between the experiments and the simulations, which indicates the applicability of in silico models to study the effects of microemboli on the brain tissue.
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Affiliation(s)
- Yidan Xue
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, United Kingdom
| | - Theodosia Georgakopoulou
- Department of Biomedical Engineering and Physics, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The Netherlands
| | - Anne-Eva van der Wijk
- Department of Biomedical Engineering and Physics, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The Netherlands
| | - Tamás I. Józsa
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, United Kingdom
| | - Ed van Bavel
- Department of Biomedical Engineering and Physics, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The Netherlands
| | - Stephen J. Payne
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, United Kingdom
- Institute of Applied Mechanics, National Taiwan University, Taipei, Taiwan
- * E-mail:
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13
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Fukuda M, Matsumura T, Suda T, Hirase H. Depth-targeted intracortical microstroke by two-photon photothrombosis in rodent brain. NEUROPHOTONICS 2022; 9:021910. [PMID: 35311215 PMCID: PMC8929553 DOI: 10.1117/1.nph.9.2.021910] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 02/24/2022] [Indexed: 05/21/2023]
Abstract
Significance: Photothrombosis is a widely used model of ischemic stroke in rodent experiments. In the photothrombosis model, the photosensitizer rose bengal (RB) is systemically introduced into the blood stream and activated by green light to induce aggregation of platelets that eventually cause vessel occlusion. Since the activation of RB is a one-photon phenomenon and the molecules in the illuminated area (light path) are subject to excitation, targeting of thrombosis is unspecific, especially in the depth dimension. We developed a photothrombosis protocol that can target a single vessel in the cortical parenchyma by two-photon excitation. Aim: We aim to induce a thrombotic stroke in the cortical parenchyma by two-photon activation of RB to confine photothrombosis within a vessel of a target depth. Approach: FITC-dextran is injected into the blood stream to visualize the cerebral blood flow in anesthetized adult mice with a cranial window. After a target vessel is chosen by two-photon imaging (950 nm), RB is injected into the blood stream. The scanning wavelength is changed to 720 nm, and photothrombosis is induced by scanning the target vessel. Results: Two-photon depth-targeted single-vessel photothrombosis was achieved with a success rate of 84.9 % ± 1.7 % and an irradiation duration of < 80 s . Attempts without RB (i.e., only with FITC) did not result in photothrombosis at the excitation wavelength of 720 nm. Conclusions: We described a protocol that achieves depth-targeted single-vessel photothrombosis by two-photon excitation. Simultaneous imaging of blood flow in the targeted vessel using FITC dextran enabled the confirmation of vessel occlusion and prevention of excess irradiation that possibly induces unintended photodamage.
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Affiliation(s)
- Masahiro Fukuda
- Kumamoto University, International Research Center for Medical Sciences, Kumamoto, Japan
- Duke-NUS Medical School, Signature Program in Neuroscience and Behavioral Disorders, Singapore
- Address all correspondence to Masahiro Fukuda, ; Hajime Hirase,
| | - Takayoshi Matsumura
- Jichi Medical University, Division of Inflammation Research, Center for Molecular Medicine, Tochigi, Japan
- National University of Singapore, Cancer Science Institute of Singapore, Singapore
| | - Toshio Suda
- Kumamoto University, International Research Center for Medical Sciences, Kumamoto, Japan
- National University of Singapore, Cancer Science Institute of Singapore, Singapore
| | - Hajime Hirase
- University of Copenhagen, Center for Translational Neuromedicine, Faculty of Health and Life Sciences, Copenhagen, Denmark
- Address all correspondence to Masahiro Fukuda, ; Hajime Hirase,
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14
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Networks behind the morphology and structural design of living systems. Phys Life Rev 2022; 41:1-21. [DOI: 10.1016/j.plrev.2022.03.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 03/04/2022] [Indexed: 01/06/2023]
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15
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Xue Y, El-Bouri WK, Józsa TI, Payne SJ. Modelling the effects of cerebral microthrombi on tissue oxygenation and cell death. J Biomech 2021; 127:110705. [PMID: 34464872 DOI: 10.1016/j.jbiomech.2021.110705] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 07/19/2021] [Accepted: 08/16/2021] [Indexed: 11/29/2022]
Abstract
Thrombectomy, the mechanical removal of a clot, is the most common way to treat ischaemic stroke with large vessel occlusions. However, perfusion cannot always be restored after such an intervention. It has been hypothesised that the absence of reperfusion is at least partially due to the clot fragments that block the downstream vessels. In this paper, we present a new way of quantifying the effects of cerebral microthrombi on oxygen transport to tissue in terms of hypoxia and ischaemia. The oxygen transport was simulated with the Green's function method on physiologically representative microvascular cubes, which was found independent of both microvascular geometry and length scale. The microthrombi occlusions were then simulated in the microvasculature, which were extravasated over time with a new thrombus extravasation model. The tissue hypoxic fraction was fitted as a sigmoidal function of vessel blockage fraction, which was then taken to be a function of time after the formation of microthrombi occlusions. A novel hypoxia-based 3-state cell death model was finally proposed to simulate the hypoxic tissue damage over time. Using the cell death model, the impact of a certain degree of microthrombi occlusions on tissue viability and microinfarct volume can be predicted over time. Quantifying the impact of microthrombi on oxygen transport and tissue death will play an important role in full brain models of ischaemic stroke and thrombectomy.
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Affiliation(s)
- Yidan Xue
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, UK.
| | - Wahbi K El-Bouri
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, UK; Liverpool Centre for Cardiovascular Science, Department of Cardiovascular and Metabolic Medicine, University of Liverpool, Liverpool, UK
| | - Tamás I Józsa
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, UK
| | - Stephen J Payne
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, UK
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16
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Graff BJ, Payne SJ, El-Bouri WK. The Ageing Brain: Investigating the Role of Age in Changes to the Human Cerebral Microvasculature With an in silico Model. Front Aging Neurosci 2021; 13:632521. [PMID: 34421568 PMCID: PMC8374868 DOI: 10.3389/fnagi.2021.632521] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 07/12/2021] [Indexed: 11/25/2022] Open
Abstract
Ageing causes extensive structural changes to the human cerebral microvasculature, which have a significant effect on capillary bed perfusion and oxygen transport. Current models of brain capillary networks in the literature focus on healthy adult brains and do not capture the effects of ageing, which is critical when studying neurodegenerative diseases. This study builds upon a statistically accurate model of the human cerebral microvasculature based on ex-vivo morphological data. This model is adapted for “healthy” ageing using in-vivo measurements from mice at three distinct age groups—young, middle-aged, and old. From this new model, blood and molecular exchange parameters are calculated such as permeability and surface-area-to-volume ratio, and compared across the three age groups. The ability to alter the model vessel-by-vessel is used to create a continuous gradient of ageing. It was found that surface-area-to-volume ratio reduced in old age by 6% and permeability by 24% from middle-age to old age, and variability within the networks also increased with age. The ageing gradient indicated a threshold in the ageing process around 75 years old, after which small changes have an amplified effect on blood flow properties. This gradient enables comparison of studies measuring cerebral properties at discrete points in time. The response of middle aged and old aged capillary beds to micro-emboli showed a lower robustness of the old age capillary bed to vessel occlusion. As the brain ages, there is thus increased vulnerability of the microvasculature—with a “tipping point” beyond which further remodeling of the microvasculature has exaggerated effects on the brain. When developing in-silico models of the brain, age is a very important consideration to accurately assess risk factors for cognitive decline and isolate early biomarkers of microvascular health.
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Affiliation(s)
- Barnaby J Graff
- Department of Engineering Science, Institute of Biomedical Engineering, University of Oxford, Oxford, United Kingdom
| | - Stephen J Payne
- Department of Engineering Science, Institute of Biomedical Engineering, University of Oxford, Oxford, United Kingdom
| | - Wahbi K El-Bouri
- Department of Engineering Science, Institute of Biomedical Engineering, University of Oxford, Oxford, United Kingdom.,Liverpool Centre for Cardiovascular Science, University of Liverpool & Liverpool Heart and Chest Hospital, Liverpool, United Kingdom.,Department of Cardiovascular and Metabolic Medicine, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
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