1
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Stamenkovic S, Schmid F, Weitermann N, Takasaki K, Bonney SK, Sosa MJ, Li Y, Bennett HC, Kim Y, Waters J, Shih AY. Impaired drainage through capillary-venous networks contributes to age-related white matter loss. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.11.579849. [PMID: 38405879 PMCID: PMC10888936 DOI: 10.1101/2024.02.11.579849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
The gradual loss of cerebral white matter contributes to cognitive decline during aging. However, microvascular networks that support the metabolic demands of white matter remain poorly defined. We used in vivo deep multi-photon imaging to characterize microvascular networks that perfuse cortical layer 6 and corpus callosum, a highly studied region of white matter in the mouse brain. We show that these deep tissues are exclusively drained by sparse and wide-reaching venules, termed principal cortical venules, which mirror vascular architecture at the human cortical-U fiber interface. During aging, capillary networks draining into deep branches of principal cortical venules are selectively constricted, reduced in density, and diminished in pericyte numbers. This causes hypo-perfusion in deep tissues, and correlates with gliosis and demyelination, whereas superficial tissues become relatively hyper-perfused. Thus, age-related impairment of capillary-venular drainage is a key vascular deficit that contributes to the unique vulnerability of cerebral white matter during brain aging.
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2
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Bjerkan J, Lancaster G, Meglič B, Kobal J, Crawford TJ, McClintock PVE, Stefanovska A. Aging affects the phase coherence between spontaneous oscillations in brain oxygenation and neural activity. Brain Res Bull 2023; 201:110704. [PMID: 37451471 DOI: 10.1016/j.brainresbull.2023.110704] [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: 04/25/2023] [Revised: 07/03/2023] [Accepted: 07/11/2023] [Indexed: 07/18/2023]
Abstract
The risk of neurodegenerative disorders increases with age, due to reduced vascular nutrition and impaired neural function. However, the interactions between cardiovascular dynamics and neural activity, and how these interactions evolve in healthy aging, are not well understood. Here, the interactions are studied by assessment of the phase coherence between spontaneous oscillations in cerebral oxygenation measured by fNIRS, the electrical activity of the brain measured by EEG, and cardiovascular functions extracted from ECG and respiration effort, all simultaneously recorded. Signals measured at rest in 21 younger participants (31.1 ± 6.9 years) and 24 older participants (64.9 ± 6.9 years) were analysed by wavelet transform, wavelet phase coherence and ridge extraction for frequencies between 0.007 and 4 Hz. Coherence between the neural and oxygenation oscillations at ∼ 0.1 Hz is significantly reduced in the older adults in 46/176 fNIRS-EEG probe combinations. This reduction in coherence cannot be accounted for in terms of reduced power, thus indicating that neurovascular interactions change with age. The approach presented promises a noninvasive means of evaluating the efficiency of the neurovascular unit in aging and disease.
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Affiliation(s)
- Juliane Bjerkan
- Lancaster University, Department of Physics, LA1 4YB, Lancaster, United Kingdom
| | - Gemma Lancaster
- Lancaster University, Department of Physics, LA1 4YB, Lancaster, United Kingdom
| | - Bernard Meglič
- University of Ljubljana Medical Centre, Department of Neurology, 1525, Ljubljana, Slovenia
| | - Jan Kobal
- University of Ljubljana Medical Centre, Department of Neurology, 1525, Ljubljana, Slovenia
| | - Trevor J Crawford
- Lancaster University, Department of Psychology, LA1 4YF, Lancaster, United Kingdom
| | | | - Aneta Stefanovska
- Lancaster University, Department of Physics, LA1 4YB, Lancaster, United Kingdom.
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3
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Walek KW, Stefan S, Lee JH, Puttigampala P, Kim AH, Park SW, Marchand PJ, Lesage F, Liu T, Huang YWA, Boas DA, Moore C, Lee J. Near-lifespan longitudinal tracking of brain microvascular morphology, topology, and flow in male mice. Nat Commun 2023; 14:2982. [PMID: 37221202 DOI: 10.1038/s41467-023-38609-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 05/09/2023] [Indexed: 05/25/2023] Open
Abstract
In age-related neurodegenerative diseases, pathology often develops slowly across the lifespan. As one example, in diseases such as Alzheimer's, vascular decline is believed to onset decades ahead of symptomology. However, challenges inherent in current microscopic methods make longitudinal tracking of such vascular decline difficult. Here, we describe a suite of methods for measuring brain vascular dynamics and anatomy in mice for over seven months in the same field of view. This approach is enabled by advances in optical coherence tomography (OCT) and image processing algorithms including deep learning. These integrated methods enabled us to simultaneously monitor distinct vascular properties spanning morphology, topology, and function of the microvasculature across all scales: large pial vessels, penetrating cortical vessels, and capillaries. We have demonstrated this technical capability in wild-type and 3xTg male mice. The capability will allow comprehensive and longitudinal study of a broad range of progressive vascular diseases, and normal aging, in key model systems.
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Affiliation(s)
- Konrad W Walek
- Warren Alpert Medical School, Brown University, Providence, RI, 02912, USA
| | - Sabina Stefan
- School of Engineering, Brown University, Providence, RI, 02912, USA
| | - Jang-Hoon Lee
- School of Engineering, Brown University, Providence, RI, 02912, USA
| | | | - Anna H Kim
- Department of Neuroscience, Brown University, Providence, RI, 02912, USA
| | - Seong Wook Park
- Department of Neuroscience, Brown University, Providence, RI, 02912, USA
| | - Paul J Marchand
- Department of Electrical Engineering, École Polytechnique de Montréal, Montréal, QC, H3T 1J4, Canada
| | - Frederic Lesage
- Department of Electrical Engineering, École Polytechnique de Montréal, Montréal, QC, H3T 1J4, Canada
| | - Tao Liu
- Department of Biostatistics, Brown University School of Public Health, Providence, RI, 02912, USA
| | - Yu-Wen Alvin Huang
- Warren Alpert Medical School, Brown University, Providence, RI, 02912, USA
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI, 02912, USA
- Carney Institute for Brain Science, Brown University, Providence, RI, 02912, USA
| | - David A Boas
- Department of Biomedical Engineering, Boston University, Boston, MA, 02215, USA
| | - Christopher Moore
- Department of Neuroscience, Brown University, Providence, RI, 02912, USA
- Carney Institute for Brain Science, Brown University, Providence, RI, 02912, USA
| | - Jonghwan Lee
- School of Engineering, Brown University, Providence, RI, 02912, USA.
- Carney Institute for Brain Science, Brown University, Providence, RI, 02912, USA.
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4
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Wei S, Wang Y, Sun Y, Gong L, Dai X, Meng H, Xu W, Ma J, Hu Q, Ma X, Peng J, Gu X. Biodegradable silk fibroin scaffold doped with mineralized collagen induces bone regeneration in rat cranial defects. Int J Biol Macromol 2023; 235:123861. [PMID: 36870644 DOI: 10.1016/j.ijbiomac.2023.123861] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 02/22/2023] [Accepted: 02/24/2023] [Indexed: 03/06/2023]
Abstract
Compared with most nondegradable or slowly degradable bone repair materials, bioactive biodegradable porous scaffolds with certain mechanical strengths can promote the regeneration of both new bone and vasculature while the cavity created by their degradation can be replaced by the infiltration of new bone tissue. Mineralized collagen (MC) is the basic structural unit of bone tissue, and silk fibroin (SF) is a natural polymer with adjustable degradation rates and superior mechanical properties. In this study, a three-dimensional porous biomimetic composite scaffold with a two-component SF-MC system was constructed based on the advantages of both materials. The spherical mineral agglomerates of the MC were uniformly distributed on the surface and inside the SF skeleton, which ensured good mechanical properties while regulating the degradation rate of the scaffold. Second, the SF-MC scaffold had good osteogenic induction of bone marrow mesenchymal stem cells (BMSCs) and preosteoblasts (MC3T3-E1) and also promoted the proliferation of MC3T3-E1 cells. Finally, in vivo 5 mm cranial defect repair experiments confirmed that the SF-MC scaffold stimulated vascular regeneration and promoted new bone regeneration in vivo by means of in situ regeneration. Overall, we believe that this low-cost biomimetic biodegradable SF-MC scaffold with many advantages has some clinical translation prospects.
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Affiliation(s)
- Shuai Wei
- Tianjin Hospital, Tianjin University, No. 406 Jiefang South Road, Hexi District, Tianjin 300211, China; Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Neural Regeneration Co-Innovation Center of Jiangsu Province, Nantong University, No. 19 Qixiu Road, Chongchuan District, Nantong 226001, China; Senior Department of Orthopedics, Beijing Key Lab of Regenerative Medicine in Orthopedics, The 1th Medical Center of PLA General Hospital, No. 28 Fuxing Road, Haidian District, Beijing 100853, China
| | - Yu Wang
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Neural Regeneration Co-Innovation Center of Jiangsu Province, Nantong University, No. 19 Qixiu Road, Chongchuan District, Nantong 226001, China; Senior Department of Orthopedics, Beijing Key Lab of Regenerative Medicine in Orthopedics, The 1th Medical Center of PLA General Hospital, No. 28 Fuxing Road, Haidian District, Beijing 100853, China
| | - Yu Sun
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Neural Regeneration Co-Innovation Center of Jiangsu Province, Nantong University, No. 19 Qixiu Road, Chongchuan District, Nantong 226001, China
| | - Leilei Gong
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Neural Regeneration Co-Innovation Center of Jiangsu Province, Nantong University, No. 19 Qixiu Road, Chongchuan District, Nantong 226001, China
| | - Xiu Dai
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Neural Regeneration Co-Innovation Center of Jiangsu Province, Nantong University, No. 19 Qixiu Road, Chongchuan District, Nantong 226001, China
| | - Haoye Meng
- Senior Department of Orthopedics, Beijing Key Lab of Regenerative Medicine in Orthopedics, The 1th Medical Center of PLA General Hospital, No. 28 Fuxing Road, Haidian District, Beijing 100853, China
| | - Wenjing Xu
- Senior Department of Orthopedics, Beijing Key Lab of Regenerative Medicine in Orthopedics, The 1th Medical Center of PLA General Hospital, No. 28 Fuxing Road, Haidian District, Beijing 100853, China
| | - Jianxiong Ma
- Tianjin Hospital, Tianjin University, No. 406 Jiefang South Road, Hexi District, Tianjin 300211, China; Institute of Orthopedics, Tianjin Hospital Tianjin University, Tianjin Key Laboratory of Orthopedic Biomechanics and Medical Engineering, No. 155 Munan Road, Heping District, Tianjin 300050, China
| | - Qian Hu
- Department of Geriatrics, The Second People's Hospital of Nantong, Affiliated Rehabilitation Hospital of Nantong University, No. 298 Xinhua Road, Chongchuan District, Nantong 226006, China
| | - Xinlong Ma
- Tianjin Hospital, Tianjin University, No. 406 Jiefang South Road, Hexi District, Tianjin 300211, China; Institute of Orthopedics, Tianjin Hospital Tianjin University, Tianjin Key Laboratory of Orthopedic Biomechanics and Medical Engineering, No. 155 Munan Road, Heping District, Tianjin 300050, China.
| | - Jiang Peng
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Neural Regeneration Co-Innovation Center of Jiangsu Province, Nantong University, No. 19 Qixiu Road, Chongchuan District, Nantong 226001, China; Senior Department of Orthopedics, Beijing Key Lab of Regenerative Medicine in Orthopedics, The 1th Medical Center of PLA General Hospital, No. 28 Fuxing Road, Haidian District, Beijing 100853, China.
| | - Xiaosong Gu
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Neural Regeneration Co-Innovation Center of Jiangsu Province, Nantong University, No. 19 Qixiu Road, Chongchuan District, Nantong 226001, China.
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5
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Butyrate promotes post-stroke outcomes in aged mice via interleukin-22. Exp Neurol 2023; 363:114351. [PMID: 36804553 DOI: 10.1016/j.expneurol.2023.114351] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 02/06/2023] [Accepted: 02/14/2023] [Indexed: 02/19/2023]
Abstract
Aging increases the risk of stroke, may exacerbate neuroinflammatory responses, reduce angiogenesis, and promote white matter damage post-stroke, all of which contribute to long-term functional recovery. Butyric acid, an important gut microbial metabolite, showed the highest correlation with the outcomes of ischemic stroke, and butyrate was selected as an effective treatment for aged stroke mice. Here, we tested the neurorestorative effect and potential therapeutic mechanisms of butyrate in aged mice with stroke. Aged male C57BL/6 J mice (17-19 months) were subjected to photothrombotic stroke. We performed butyrate supplementation in the drinking water for 3 weeks before surgery until 14 days after the stroke. At 14 days after ischemic stroke, white matter damage, leukocyte infiltration, and blood-brain barrier permeability were all decreased in the aged stroke mice that received the butyrate treatment, which also improved neurological outcomes by stimulating angiogenesis. Stroke reduces the level of interleukin-22 (IL-22) and butyrate treatment significantly enhanced IL-22 expression in the brain. To further validate the mechanisms of butyrate promoting neurological function after stroke, monoclonal antibodies were used to block IL-22 in aged stroke mice when butyrate treatment was provided. Blocking IL-22 in butyrate-treated aged stroke fails to improve functional outcomes and attenuated butyrate-induced angiogenesis, increased axon/white matter density and blood-brain barrier (BBB) integrity, but has no effect on inflammatory cells infiltration. In conclusion, butyrate improves outcomes in aged mice after stroke by promoting angiogenesis and BBB integrity and reducing leukocyte infiltration. To some extent, IL-22 may contribute to butyrate treatment induced vascular remodeling and increased BBB integrity responses in aged stroke mice.
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6
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Stobart JL, Erlebach E, Glück C, Huang SF, Barrett MJ, Li M, Vinogradov SA, Klohs J, Zarb Y, Keller A, Weber B. Altered hemodynamics and vascular reactivity in a mouse model with severe pericyte deficiency. J Cereb Blood Flow Metab 2022; 43:763-777. [PMID: 36545806 PMCID: PMC10108184 DOI: 10.1177/0271678x221147366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Pericytes are the mural cells of the microvascular network that are in close contact with underlying endothelial cells. Endothelial-secreted PDGFB leads to recruitment of pericytes to the vessel wall, but this is disrupted in Pdgfbret/ret mice when the PDGFB retention motif is deleted. This results in severely reduced pericyte coverage on blood vessels. In this study, we investigated vascular abnormalities and hemodynamics in Pdgfbret/ret mice throughout the cerebrovascular network and in different cortical layers by in vivo two-photon microscopy. We confirmed that Pdgfbret/ret mice are severely deficient in pericytes throughout the vascular network, with enlarged brain blood vessels and a reduced number of vessel branches. Red blood cell velocity, linear density, and tube hematocrit were reduced in Pdgfbret/ret mice, which may impair oxygen delivery to the tissue. We also measured intravascular PO2 and found that concentrations were higher in cortical Layer 2/3 in Pdgfbret/ret mice, indicative of reduced blood oxygen extraction. Finally, we found that Pdgfbret/ret mice had a reduced capacity for vasodilation in response to an acetazolamide challenge during functional MRI imaging. Taken together, these results suggest that severe pericyte deficiency can lead to vascular abnormalities and altered cerebral blood flow, reminiscent of pathologies such as arteriovenous malformations.
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Affiliation(s)
- Jillian L Stobart
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, Zurich, Switzerland.,College of Pharmacy, University of Manitoba, Winnipeg, MB, Canada
| | - Eva Erlebach
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, Zurich, Switzerland
| | - Chaim Glück
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, Zurich, Switzerland
| | - Sheng-Fu Huang
- Neuroscience Center, University and ETH Zurich, Zurich, Switzerland.,Department of Neurosurgery, University Hospital Zurich, University of Zurich, Zürich, Switzerland
| | - Matthew Jp Barrett
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, Zurich, Switzerland
| | - Max Li
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, Zurich, Switzerland
| | - Sergei A Vinogradov
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Jan Klohs
- Neuroscience Center, University and ETH Zurich, Zurich, Switzerland.,Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Yvette Zarb
- Neuroscience Center, University and ETH Zurich, Zurich, Switzerland.,Department of Neurosurgery, University Hospital Zurich, University of Zurich, Zürich, Switzerland
| | - Annika Keller
- Neuroscience Center, University and ETH Zurich, Zurich, Switzerland.,Department of Neurosurgery, University Hospital Zurich, University of Zurich, Zürich, Switzerland
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, Zurich, Switzerland
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7
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Intensity distribution segmentation in ultrafast Doppler combined with scanning laser confocal microscopy for assessing vascular changes associated with ageing in murine hippocampi. Sci Rep 2022; 12:6784. [PMID: 35473942 PMCID: PMC9042937 DOI: 10.1038/s41598-022-10457-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 04/06/2022] [Indexed: 11/21/2022] Open
Abstract
The hippocampus plays an important role in learning and memory, requiring high-neuronal oxygenation. Understanding the relationship between blood flow and vascular structure—and how it changes with ageing—is physiologically and anatomically relevant. Ultrafast Doppler (\documentclass[12pt]{minimal}
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\begin{document}$$\mu$$\end{document}μDoppler) and scanning laser confocal microscopy (SLCM) are powerful imaging modalities that can measure in vivo cerebral blood volume (CBV) and post mortem vascular structure, respectively. Here, we apply both imaging modalities to a cross-sectional and longitudinal study of hippocampi vasculature in wild-type mice brains. We introduce a segmentation of CBV distribution obtained from \documentclass[12pt]{minimal}
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\begin{document}$$\mu$$\end{document}μDoppler and show that this mice-independent and mesoscopic measurement is correlated with vessel volume fraction (VVF) distribution obtained from SLCM—e.g., high CBV relates to specific vessel locations with large VVF. Moreover, we find significant changes in CBV distribution and vasculature due to ageing (5 vs. 21 month-old mice), highlighting the sensitivity of our approach. Overall, we are able to associate CBV with vascular structure—and track its longitudinal changes—at the artery-vein, venules, arteriole, and capillary levels. We believe that this combined approach can be a powerful tool for studying other acute (e.g., brain injuries), progressive (e.g., neurodegeneration) or induced pathological changes.
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8
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Merlo A, Berg M, Duru P, Risso F, Davit Y, Lorthois S. A few upstream bifurcations drive the spatial distribution of red blood cells in model microfluidic networks. SOFT MATTER 2022; 18:1463-1478. [PMID: 35088062 DOI: 10.1039/d1sm01141c] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The physics of blood flow in small vessel networks is dominated by the interactions between Red Blood Cells (RBCs), plasma and blood vessel walls. The resulting couplings between the microvessel network architecture and the heterogeneous distribution of RBCs at network-scale are still poorly understood. The main goal of this paper is to elucidate how a local effect, such as RBC partitioning at individual bifurcations, interacts with the global structure of the flow field to induce specific preferential locations of RBCs in model microfluidic networks. First, using experimental results, we demonstrate that persistent perturbations to the established hematocrit profile after diverging bifurcations may bias RBC partitioning at the next bifurcations. By performing a sensitivity analysis based upon network models of RBC flow, we show that these perturbations may propagate from bifurcation to bifurcation, leading to an outsized impact of a few crucial upstream bifurcations on the distribution of RBCs at network-scale. Based on measured hematocrit profiles, we further construct a modified RBC partitioning model that accounts for the incomplete relaxation of RBCs at these bifurcations. This model allows us to explain how the flow field results in a single pattern of RBC preferential location in some networks, while it leads to the emergence of two different patterns of RBC preferential location in others. Our findings have important implications in understanding and modeling blood flow in physiological and pathological conditions.
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Affiliation(s)
- Adlan Merlo
- Institut de Mécanique des Fluides de Toulouse, IMFT, Université de Toulouse, CNRS, Toulouse, France.
| | - Maxime Berg
- Institut de Mécanique des Fluides de Toulouse, IMFT, Université de Toulouse, CNRS, Toulouse, France.
| | - Paul Duru
- Institut de Mécanique des Fluides de Toulouse, IMFT, Université de Toulouse, CNRS, Toulouse, France.
| | - Frédéric Risso
- Institut de Mécanique des Fluides de Toulouse, IMFT, Université de Toulouse, CNRS, Toulouse, France.
| | - Yohan Davit
- Institut de Mécanique des Fluides de Toulouse, IMFT, Université de Toulouse, CNRS, Toulouse, France.
| | - Sylvie Lorthois
- Institut de Mécanique des Fluides de Toulouse, IMFT, Université de Toulouse, CNRS, Toulouse, France.
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9
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Lowerison MR, Sekaran NVC, Zhang W, Dong Z, Chen X, Llano DA, Song P. Aging-related cerebral microvascular changes visualized using ultrasound localization microscopy in the living mouse. Sci Rep 2022; 12:619. [PMID: 35022482 PMCID: PMC8755738 DOI: 10.1038/s41598-021-04712-8] [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: 08/19/2021] [Accepted: 12/14/2021] [Indexed: 01/09/2023] Open
Abstract
Aging-related cognitive decline is an emerging health crisis; however, no established unifying mechanism has been identified for the cognitive impairments seen in an aging population. A vascular hypothesis of cognitive decline has been proposed but is difficult to test given the requirement of high-fidelity microvascular imaging resolution with a broad and deep brain imaging field of view, which is restricted by the fundamental trade-off of imaging penetration depth and resolution. Super-resolution ultrasound localization microscopy (ULM) offers a potential solution by exploiting circulating microbubbles to achieve a vascular resolution approaching the capillary scale without sacrificing imaging depth. In this report, we apply ULM imaging to a mouse model of aging and quantify differences in cerebral vascularity, blood velocity, and vessel tortuosity across several brain regions. We found significant decreases in blood velocity, and significant increases in vascular tortuosity, across all brain regions in the aged cohort, and significant decreases in blood volume in the cerebral cortex. These data provide the first-ever ULM measurements of subcortical microvascular dynamics in vivo within the context of the aging brain and reveal that aging has a major impact on these measurements.
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Affiliation(s)
- Matthew R Lowerison
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Department of Electrical and Computer Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 N. Mathews Ave, Urbana, IL, 61801, USA
| | - Nathiya Vaithiyalingam Chandra Sekaran
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Department of Molecular and Integrative Physiology, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 N. Mathews Ave, Urbana, IL, 61801, USA
| | - Wei Zhang
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Department of Electrical and Computer Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 N. Mathews Ave, Urbana, IL, 61801, USA
- Department of Medical Ultrasound, Tongji Hospital, Tongji Medical College, Wuhan City, Hubei Province, China
| | - Zhijie Dong
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Department of Electrical and Computer Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 N. Mathews Ave, Urbana, IL, 61801, USA
| | - Xi Chen
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Department of Electrical and Computer Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 N. Mathews Ave, Urbana, IL, 61801, USA
| | - Daniel A Llano
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
- Department of Molecular and Integrative Physiology, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 N. Mathews Ave, Urbana, IL, 61801, USA.
| | - Pengfei Song
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
- Department of Electrical and Computer Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 N. Mathews Ave, Urbana, IL, 61801, USA.
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10
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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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11
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A simulation study investigating potential diffusion-based MRI signatures of microstrokes. Sci Rep 2021; 11:14229. [PMID: 34244549 PMCID: PMC8271016 DOI: 10.1038/s41598-021-93503-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 06/22/2021] [Indexed: 02/06/2023] Open
Abstract
Recent studies suggested that cerebrovascular micro-occlusions, i.e. microstokes, could lead to ischemic tissue infarctions and cognitive deficits. Due to their small size, identifying measurable biomarkers of these microvascular lesions remains a major challenge. This work aims to simulate potential MRI signatures combining arterial spin labeling (ASL) and multi-directional diffusion-weighted imaging (DWI). Driving our hypothesis are recent observations demonstrating a radial reorientation of microvasculature around the micro-infarction locus during recovery in mice. Synthetic capillary beds, randomly- and radially-oriented, and optical coherence tomography (OCT) angiograms, acquired in the barrel cortex of mice (n = 5) before and after inducing targeted photothrombosis, were analyzed. Computational vascular graphs combined with a 3D Monte-Carlo simulator were used to characterize the magnetic resonance (MR) response, encompassing the effects of magnetic field perturbations caused by deoxyhemoglobin, and the advection and diffusion of the nuclear spins. We quantified the minimal intravoxel signal loss ratio when applying multiple gradient directions, at varying sequence parameters with and without ASL. With ASL, our results demonstrate a significant difference (p < 0.05) between the signal-ratios computed at baseline and 3 weeks after photothrombosis. The statistical power further increased (p < 0.005) using angiograms measured at week 4. Without ASL, no reliable signal change was found. We found that higher ratios, and accordingly improved significance, were achieved at lower magnetic field strengths (e.g., B0 = 3T) and shorter echo time TE (< 16 ms). Our simulations suggest that microstrokes might be characterized through ASL-DWI sequence, providing necessary insights for posterior experimental validations, and ultimately, future translational trials.
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12
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Brain capillary pericytes exert a substantial but slow influence on blood flow. Nat Neurosci 2021; 24:633-645. [PMID: 33603231 PMCID: PMC8102366 DOI: 10.1038/s41593-020-00793-2] [Citation(s) in RCA: 168] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 12/23/2020] [Indexed: 01/30/2023]
Abstract
The majority of the brain's vasculature is composed of intricate capillary networks lined by capillary pericytes. However, it remains unclear whether capillary pericytes influence blood flow. Using two-photon microscopy to observe and manipulate brain capillary pericytes in vivo, we find that their optogenetic stimulation decreases lumen diameter and blood flow, but with slower kinetics than similar stimulation of mural cells on upstream pial and precapillary arterioles. This slow vasoconstriction was inhibited by the clinically used vasodilator fasudil, a Rho-kinase inhibitor that blocks contractile machinery. Capillary pericytes were also slower to constrict back to baseline following hypercapnia-induced dilation, and slower to dilate towards baseline following optogenetically induced vasoconstriction. Optical ablation of single capillary pericytes led to sustained local dilation and a doubling of blood cell flux selectively in capillaries lacking pericyte contact. These data indicate that capillary pericytes contribute to basal blood flow resistance and slow modulation of blood flow throughout the brain.
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13
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Hartung G, Badr S, Moeini M, Lesage F, Kleinfeld D, Alaraj A, Linninger A. Voxelized simulation of cerebral oxygen perfusion elucidates hypoxia in aged mouse cortex. PLoS Comput Biol 2021; 17:e1008584. [PMID: 33507970 PMCID: PMC7842915 DOI: 10.1371/journal.pcbi.1008584] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 11/30/2020] [Indexed: 12/13/2022] Open
Abstract
Departures of normal blood flow and metabolite distribution from the cerebral microvasculature into neuronal tissue have been implicated with age-related neurodegeneration. Mathematical models informed by spatially and temporally distributed neuroimage data are becoming instrumental for reconstructing a coherent picture of normal and pathological oxygen delivery throughout the brain. Unfortunately, current mathematical models of cerebral blood flow and oxygen exchange become excessively large in size. They further suffer from boundary effects due to incomplete or physiologically inaccurate computational domains, numerical instabilities due to enormous length scale differences, and convergence problems associated with condition number deterioration at fine mesh resolutions. Our proposed simple finite volume discretization scheme for blood and oxygen microperfusion simulations does not require expensive mesh generation leading to the critical benefit that it drastically reduces matrix size and bandwidth of the coupled oxygen transfer problem. The compact problem formulation yields rapid and stable convergence. Moreover, boundary effects can effectively be suppressed by generating very large replica of the cortical microcirculation in silico using an image-based cerebrovascular network synthesis algorithm, so that boundaries of the perfusion simulations are far removed from the regions of interest. Massive simulations over sizeable portions of the cortex with feature resolution down to the micron scale become tractable with even modest computer resources. The feasibility and accuracy of the novel method is demonstrated and validated with in vivo oxygen perfusion data in cohorts of young and aged mice. Our oxygen exchange simulations quantify steep gradients near penetrating blood vessels and point towards pathological changes that might cause neurodegeneration in aged brains. This research aims to explain mechanistic interactions between anatomical structures and how they might change in diseases or with age. Rigorous quantification of age-related changes is of significant interest because it might aide in the search for imaging biomarkers for dementia and Alzheimer’s disease. Brain function critically depends on the maintenance of physiological blood supply and metabolism in the cortex. Disturbances to adequate perfusion have been linked to age-related neurodegeneration. However, the precise correlation between age-related hemodynamic changes and the resulting decline in oxygen delivery is not well understood and has not been quantified. Therefore, we introduce a new compact, and therefore highly scalable, computational method for predicting the physiological relationship between hemodynamics and cortical oxygen perfusion for large sections of the cortical microcirculation. We demonstrate the novel mesh generation-free (MGF), multi-scale simulation approach through realistic in vivo case studies of cortical microperfusion in the mouse brain. We further validate mechanistic correlations and a quantitative relationship between blood flow and brain oxygenation using experimental data from cohorts of young, middle aged and old mouse brains. Our computational approach overcomes size and performance limitations of previous unstructured meshing techniques to enable the prediction of oxygen tension with a spatial resolution of least two orders of magnitude higher than previously possible. Our simulation results support the hypothesis that structural changes in the microvasculature induce hypoxic pockets in the aged brain that are absent in the healthy, young mouse.
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Affiliation(s)
- Grant Hartung
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Shoale Badr
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Mohammad Moeini
- Polytechnique Montréal, Department of Electrical Engineering, Montreal, Canada
| | - Frédéric Lesage
- Polytechnique Montréal, Department of Electrical Engineering, Montreal, Canada
| | - David Kleinfeld
- Department of Physics, University of California San Diego, San Diego, California, United States of America
| | - Ali Alaraj
- Department of Neurosurgery, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Andreas Linninger
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois, United States of America
- Department of Neurosurgery, University of Illinois at Chicago, Chicago, Illinois, United States of America
- * E-mail:
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14
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Watson AN, Berthiaume AA, Faino AV, McDowell KP, Bhat NR, Hartmann DA, Shih AY. Mild pericyte deficiency is associated with aberrant brain microvascular flow in aged PDGFRβ +/- mice. J Cereb Blood Flow Metab 2020; 40:2387-2400. [PMID: 31987006 PMCID: PMC7820684 DOI: 10.1177/0271678x19900543] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The receptor tyrosine kinase PDGFRβ is essential for pericyte migration to the endothelium. In mice lacking one allele of PDGFRβ (PDGFRβ+/-), previous reports have described an age-dependent loss of pericytes in the brain, leading to cerebrovascular dysfunction and subsequent neurodegeneration reminiscent of that seen in Alzheimer's disease and vascular dementia. We examined 12-20-month-old PDGFRβ+/- mice to better understand how pericyte loss affects brain microvascular structure and perfusion in vivo. We observed a mild reduction of cortical pericyte number in PDGFRβ+/- mice (27% fewer cell bodies) compared to controls, but no decrease in pericyte coverage of the endothelium. This mild degree of pericyte loss caused no discernable change in cortical microvascular density, length, basal diameter or reactivity to hypercapnia. Yet, it was associated with an increase in basal blood cell velocity, primarily in pre-capillary arterioles. Taken together, our results suggest that mild pericyte loss can lead to aberrant cerebral blood flow despite a lack of apparent effect on microvascular structure and reactivity.
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Affiliation(s)
- Ashley N Watson
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA
| | - Andree-Anne Berthiaume
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA.,Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA, USA
| | - Anna V Faino
- Children's Core for Biomedical Statistics, Seattle Children's Research Institute, Seattle, WA, USA
| | - Konnor P McDowell
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA.,Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA, USA
| | - Narayan R Bhat
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA
| | - David A Hartmann
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA
| | - Andy Y Shih
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA.,Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA, USA.,Children's Core for Biomedical Statistics, Seattle Children's Research Institute, Seattle, WA, USA.,Department of Pediatrics, University of Washington, Seattle, WA, USA
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15
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Costea L, Mészáros Á, Bauer H, Bauer HC, Traweger A, Wilhelm I, Farkas AE, Krizbai IA. The Blood-Brain Barrier and Its Intercellular Junctions in Age-Related Brain Disorders. Int J Mol Sci 2019; 20:ijms20215472. [PMID: 31684130 PMCID: PMC6862160 DOI: 10.3390/ijms20215472] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2019] [Revised: 10/30/2019] [Accepted: 11/01/2019] [Indexed: 12/14/2022] Open
Abstract
With age, our cognitive skills and abilities decline. Maybe starting as an annoyance, this decline can become a major impediment to normal daily life. Recent research shows that the neurodegenerative disorders responsible for age associated cognitive dysfunction are mechanistically linked to the state of the microvasculature in the brain. When the microvasculature does not function properly, ischemia, hypoxia, oxidative stress and related pathologic processes ensue, further damaging vascular and neural function. One of the most important and specialized functions of the brain microvasculature is the blood-brain barrier (BBB), which controls the movement of molecules between blood circulation and the brain parenchyma. In this review, we are focusing on tight junctions (TJs), the multiprotein complexes that play an important role in establishing and maintaining barrier function. After a short introduction of the cell types that modulate barrier function via intercellular communication, we examine how age, age related pathologies and the aging of the immune system affects TJs. Then, we review how the TJs are affected in age associated neurodegenerative disorders: Alzheimer's disease and Parkinson's disease. Lastly, we summarize the TJ aspects of Huntington's disease and schizophrenia. Barrier dysfunction appears to be a common denominator in neurological disorders, warranting detailed research into the molecular mechanisms behind it. Learning the commonalities and differences in the pathomechanism of the BBB injury in different neurological disorders will predictably lead to development of new therapeutics that improve our life as we age.
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Affiliation(s)
- Laura Costea
- Institute of Life Sciences, Vasile Goldiş Western University of Arad, 310414 Arad, Romania.
| | - Ádám Mészáros
- Institute of Biophysics, Biological Research Centre, 6726 Szeged, Hungary.
- Doctoral School of Biology, University of Szeged, 6726 Szeged, Hungary.
| | - Hannelore Bauer
- Department of Biological Sciences, University of Salzburg, 5020 Salzburg, Austria.
| | - Hans-Christian Bauer
- Institute of Tendon and Bone Regeneration, Paracelsus Medical University-Spinal Cord Injury and Tissue Regeneration Center Salzburg, 5020 Salzburg, Austria.
| | - Andreas Traweger
- Institute of Tendon and Bone Regeneration, Paracelsus Medical University-Spinal Cord Injury and Tissue Regeneration Center Salzburg, 5020 Salzburg, Austria.
| | - Imola Wilhelm
- Institute of Life Sciences, Vasile Goldiş Western University of Arad, 310414 Arad, Romania.
- Institute of Biophysics, Biological Research Centre, 6726 Szeged, Hungary.
| | - Attila E Farkas
- Institute of Biophysics, Biological Research Centre, 6726 Szeged, Hungary.
- Department of Physiology, Anatomy and Neuroscience, University of Szeged, 6726 Szeged, Hungary.
| | - István A Krizbai
- Institute of Life Sciences, Vasile Goldiş Western University of Arad, 310414 Arad, Romania.
- Institute of Biophysics, Biological Research Centre, 6726 Szeged, Hungary.
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16
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Lu Y, Zhang C, Lu X, Moeini M, Thorin E, Lesage F. Impact of atherosclerotic disease on cerebral microvasculature and tissue oxygenation in awake LDLR-/-hApoB+/+ transgenic mice. NEUROPHOTONICS 2019; 6:045003. [PMID: 31673566 PMCID: PMC6811703 DOI: 10.1117/1.nph.6.4.045003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 09/17/2019] [Indexed: 05/17/2023]
Abstract
We explore cortical microvasculature changes during the progression of atherosclerosis using young and old transgenic atherosclerotic (ATX) mice with thinned-skull cranial window. In awake animals, exploiting intrinsic signal optical imaging, Doppler optical coherence tomography, and two-photon microscopy, we investigate how the progression of atherosclerotic disease affects the morphology and function of cortical microvasculature as well as baseline cerebral tissue oxygenation. Results show that aged ATX mice exhibited weaker hemodynamic response in the somatosensory cortex to whisker stimulation and that the diameter of their descending arterioles and associated mean blood flow decreased significantly compared with the young ATX group. Data from two-photon phosphorescence lifetime microscopy indicate that old ATX mice had lower and more heterogeneous partial pressure of oxygen ( PO 2 ) in cortical tissue than young ATX mice. In addition, hypoxic micropockets in cortical tissue were found in old, but not young, ATX mice. Capillary red blood cell (RBC) flux, RBC velocity, RBC velocity heterogeneity, hematocrit, and diameter were also measured using line scans with two-photon fluorescence microscopy. When compared with the young group, RBC flux, velocity, and hematocrit decreased and RBC velocity heterogeneity increased in old ATX mice, presumably due to disturbed blood supply from arterioles that were affected by atherosclerosis. Finally, dilation of capillaries in old ATX mice was observed, which suggests that capillaries play an active role in compensating for an oxygen deficit in brain tissue.
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Affiliation(s)
- Yuankang Lu
- École Polytechnique de Montréal, Laboratoire d’Imagerie optique et moléculaire, Montréal, Québec, Canada
| | - Cong Zhang
- Institut de Cardiologie de Montréal, Montréal, Québec, Canada
| | - Xuecong Lu
- École Polytechnique de Montréal, Laboratoire d’Imagerie optique et moléculaire, Montréal, Québec, Canada
| | - Mohammad Moeini
- Amirkabir University of Technology (Tehran Polytechnic), Biomedical Engineering Department, Tehran, Iran
| | - Eric Thorin
- Institut de Cardiologie de Montréal, Montréal, Québec, Canada
- Université de Montréal, Department of Pharmacology and Physiology, Faculty of Medicine, Montréal, Québec, Canada
| | - Frédéric Lesage
- École Polytechnique de Montréal, Laboratoire d’Imagerie optique et moléculaire, Montréal, Québec, Canada
- Institut de Cardiologie de Montréal, Montréal, Québec, Canada
- Address all correspondence to Frédéric Lesage, E-mail:
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17
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Atherosclerosis is associated with a decrease in cerebral microvascular blood flow and tissue oxygenation. PLoS One 2019; 14:e0221547. [PMID: 31469849 PMCID: PMC6716780 DOI: 10.1371/journal.pone.0221547] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 08/11/2019] [Indexed: 02/07/2023] Open
Abstract
Chronic atherosclerosis may cause cerebral hypoperfusion and inadequate brain oxygenation, contributing to the progression of cognitive decline. In this study, we exploited two-photon phosphorescence lifetime microscopy to measure the absolute partial pressure of oxygen (PO2) in cortical tissue in both young and old LDLR-/-, hApoB100+/+ mice, spontaneously developing atherosclerosis with age. Capillary red-blood-cell (RBC) speed, flux, hematocrit and capillary diameter were also measured by two-photon imaging of FITC-labelled blood plasma. Our results show positive correlations between RBC speed, flux, diameter and capillary-adjacent tissue PO2. When compared to the young mice, we observed lower tissue PO2, lower RBC speed and flux, and smaller capillary diameter in the old atherosclerotic mice. The old mice also exhibited a higher spatial heterogeneity of tissue PO2, and RBC speed and flux, suggesting a less efficient oxygen extraction.
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18
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Kopylova VS, Boronovskiy SE, Nartsissov YR. Fundamental constraints of vessels network architecture properties revealed by reconstruction of a rat brain vasculature. Math Biosci 2019; 315:108237. [PMID: 31377216 DOI: 10.1016/j.mbs.2019.108237] [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: 11/14/2018] [Revised: 07/31/2019] [Accepted: 07/31/2019] [Indexed: 10/26/2022]
Abstract
The studies of mammalian vasculature are an essential part of biomedical research, enabling the development of physiological understanding and forming the background of medical techniques and therapy. Despite the fact that the basic principles of vessel network description were established in the first quarter of the twentieth century, a digital model describing the vasculature in full accordance with experimental data has not yet been created. In the present study, we combine the determined structure design of basic arterial vessels with the stochastic creation of small vessel networks. By the example of rat brain arterial network model it was shown that the arterial blood volume and the magnitude of the blood flow impose a limitation on the network architecture. In particular, the bifurcation exponent (γ) should not be less than 2.7, and the optimal value of this parameter lies in the range of 2.9-3.0. Although the networks with a low γ appear as branched and complex, they do not fill out the phantom properly. Thus, the architecture of the vasculature is fundamentally determined by topological geometrical parameters.
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Affiliation(s)
- V S Kopylova
- Department of mathematical modelling and statistical analysis, Institute of cytochemistry and molecular pharmacology, Moscow, Russia.
| | - S E Boronovskiy
- Department of mathematical modelling and statistical analysis, Institute of cytochemistry and molecular pharmacology, Moscow, Russia
| | - Ya R Nartsissov
- Department of mathematical modelling and statistical analysis, Institute of cytochemistry and molecular pharmacology, Moscow, Russia
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19
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Li B, Esipova TV, Sencan I, Kılıç K, Fu B, Desjardins M, Moeini M, Kura S, Yaseen MA, Lesage F, Østergaard L, Devor A, Boas DA, Vinogradov SA, Sakadžić S. More homogeneous capillary flow and oxygenation in deeper cortical layers correlate with increased oxygen extraction. eLife 2019; 8:42299. [PMID: 31305237 PMCID: PMC6636997 DOI: 10.7554/elife.42299] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 07/01/2019] [Indexed: 01/01/2023] Open
Abstract
Our understanding of how capillary blood flow and oxygen distribute across cortical layers to meet the local metabolic demand is incomplete. We addressed this question by using two-photon imaging of resting-state microvascular oxygen partial pressure (PO2) and flow in the whisker barrel cortex in awake mice. Our measurements in layers I-V show that the capillary red-blood-cell flux and oxygenation heterogeneity, and the intracapillary resistance to oxygen delivery, all decrease with depth, reaching a minimum around layer IV, while the depth-dependent oxygen extraction fraction is increased in layer IV, where oxygen demand is presumably the highest. Our findings suggest that more homogeneous distribution of the physiological observables relevant to oxygen transport to tissue is an important part of the microvascular network adaptation to local brain metabolism. These results will inform the biophysical models of layer-specific cerebral oxygen delivery and consumption and improve our understanding of the diseases that affect cerebral microcirculation.
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Affiliation(s)
- Baoqiang Li
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, United States
| | - Tatiana V Esipova
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, United States.,Department of Chemistry, University of Pennsylvania, Philadelphia, United States
| | - Ikbal Sencan
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, United States
| | - Kıvılcım Kılıç
- Department of Neurosciences, University of California, San Diego, La Jolla, United States
| | - Buyin Fu
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, United States
| | - Michele Desjardins
- Department of Radiology, University of California, San Diego, La Jolla, United States
| | - Mohammad Moeini
- Institute of Biomedical Engineering, École Polytechnique de Montréal, Montréal, Canada.,Research Centre, Montreal Heart Institute, Montréal, Canada
| | - Sreekanth Kura
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, United States
| | - Mohammad A Yaseen
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, United States
| | - Frederic Lesage
- Institute of Biomedical Engineering, École Polytechnique de Montréal, Montréal, Canada.,Research Centre, Montreal Heart Institute, Montréal, Canada
| | - Leif Østergaard
- Center of Functionally Integrative Neuroscience and MINDLab, Institute of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Anna Devor
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, United States.,Department of Neurosciences, University of California, San Diego, La Jolla, United States.,Department of Radiology, University of California, San Diego, La Jolla, United States
| | - David A Boas
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, United States.,Department of Biomedical Engineering, Boston University, Boston, United States
| | - Sergei A Vinogradov
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, United States.,Department of Chemistry, University of Pennsylvania, Philadelphia, United States
| | - Sava Sakadžić
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, United States
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20
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Zhang C, Tabatabaei M, Bélanger S, Girouard H, Moeini M, Lu X, Lesage F. Astrocytic endfoot Ca 2+ correlates with parenchymal vessel responses during 4-AP induced epilepsy: An in vivo two-photon lifetime microscopy study. J Cereb Blood Flow Metab 2019; 39:260-271. [PMID: 28792278 PMCID: PMC6365602 DOI: 10.1177/0271678x17725417] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Neurovascular coupling (NVC) underlying the local increase in blood flow during neural activity forms the basis of functional brain imaging and is altered in epilepsy. Because astrocytic calcium (Ca2+) signaling is involved in NVC, this study investigates the role of this pathway in epilepsy. Here, we exploit 4-AP induced epileptic events to show that absolute Ca2+ concentration in cortical astrocyte endfeet in vivo correlates with the diameter of precapillary arterioles during neural activity. We simultaneously monitored free Ca2+ concentration in astrocytic endfeet with the Ca2+-sensitive indicator OGB-1 and diameter of adjacent arterioles in the somatosensory cortex of adult mice by two-photon fluorescence lifetime measurements following 4-AP injection. Our results reveal that, regardless of the mechanism by which astrocytic endfoot Ca2+ was elevated during epileptic events, increases in Ca2+ associated with vasodilation for each individual ictal event in the focus. In the remote area, increases in Ca2+ correlated with vasoconstriction at the onset of seizure and vasodilation during the later part of the seizure. Furthermore, a slow increase in absolute Ca2+ with time following multiple seizures was observed, which in turn, correlated with a trend of arteriolar constriction both at the epileptic focus and remote areas.
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Affiliation(s)
- Cong Zhang
- 1 Department of Electrical Engineering, École Polytechnique de Montréal, Montreal, Canada.,2 Montreal Heart Institute, Montreal, Quebec, Canada
| | - Maryam Tabatabaei
- 3 Department of Computer Engineering, École Polytechnique de Montréal, Montreal, Canada
| | - Samuel Bélanger
- 1 Department of Electrical Engineering, École Polytechnique de Montréal, Montreal, Canada
| | - Hélène Girouard
- 4 Department of Pharmacology, University of Montreal, Montreal, Canada
| | - Mohammad Moeini
- 1 Department of Electrical Engineering, École Polytechnique de Montréal, Montreal, Canada.,2 Montreal Heart Institute, Montreal, Quebec, Canada
| | - Xuecong Lu
- 1 Department of Electrical Engineering, École Polytechnique de Montréal, Montreal, Canada.,2 Montreal Heart Institute, Montreal, Quebec, Canada
| | - Frédéric Lesage
- 1 Department of Electrical Engineering, École Polytechnique de Montréal, Montreal, Canada.,2 Montreal Heart Institute, Montreal, Quebec, Canada
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21
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Osipova ED, Komleva YK, Morgun AV, Lopatina OL, Panina YA, Olovyannikova RY, Vais EF, Salmin VV, Salmina AB. Designing in vitro Blood-Brain Barrier Models Reproducing Alterations in Brain Aging. Front Aging Neurosci 2018; 10:234. [PMID: 30127733 PMCID: PMC6088457 DOI: 10.3389/fnagi.2018.00234] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 07/17/2018] [Indexed: 12/22/2022] Open
Abstract
Blood-brain barrier (BBB) modeling in vitro is a huge area of research covering study of intercellular communications and development of BBB, establishment of specific properties that provide controlled permeability of the barrier. Current approaches in designing new BBB models include development of new (bio) scaffolds supporting barriergenesis/angiogenesis and BBB integrity; use of methods enabling modulation of BBB permeability; application of modern analytical techniques for screening the transfer of metabolites, bio-macromolecules, selected drug candidates and drug delivery systems; establishment of 3D models; application of microfluidic technologies; reconstruction of microphysiological systems with the barrier constituents. Acceptance of idea that BBB in vitro models should resemble real functional activity of the barrier in different periods of ontogenesis and in different (patho) physiological conditions leads to proposal that establishment of BBB in vitro model with alterations specific for aging brain is one of current challenges in neurosciences and bioengineering. Vascular dysfunction in the aging brain often associates with leaky BBB, alterations in perivascular microenvironment, neuroinflammation, perturbed neuronal and astroglial activity within the neurovascular unit, impairments in neurogenic niches where microvascular scaffold plays a key regulatory role. The review article is focused on aging-related alterations in BBB and current approaches to development of “aging” BBB models in vitro.
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Affiliation(s)
- Elena D Osipova
- Department of Biochemistry, Medical, Pharmaceutical & Toxicological Chemistry, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia.,Research Institute of Molecular Medicine & Pathobiochemistry, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia
| | - Yulia K Komleva
- Department of Biochemistry, Medical, Pharmaceutical & Toxicological Chemistry, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia.,Research Institute of Molecular Medicine & Pathobiochemistry, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia
| | - Andrey V Morgun
- Department of Medical and Biological Physics, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia
| | - Olga L Lopatina
- Department of Biochemistry, Medical, Pharmaceutical & Toxicological Chemistry, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia.,Research Institute of Molecular Medicine & Pathobiochemistry, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia
| | - Yulia A Panina
- Department of Biochemistry, Medical, Pharmaceutical & Toxicological Chemistry, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia
| | - Raissa Ya Olovyannikova
- Department of Biochemistry, Medical, Pharmaceutical & Toxicological Chemistry, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia
| | - Elizaveta F Vais
- Department of Biochemistry, Medical, Pharmaceutical & Toxicological Chemistry, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia
| | - Vladimir V Salmin
- Department of Medical and Biological Physics, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia
| | - Alla B Salmina
- Department of Biochemistry, Medical, Pharmaceutical & Toxicological Chemistry, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia.,Research Institute of Molecular Medicine & Pathobiochemistry, Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Krasnoyarsk, Russia
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22
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Lourenço CF, Ledo A, Caetano M, Barbosa RM, Laranjinha J. Age-Dependent Impairment of Neurovascular and Neurometabolic Coupling in the Hippocampus. Front Physiol 2018; 9:913. [PMID: 30065657 PMCID: PMC6056650 DOI: 10.3389/fphys.2018.00913] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 06/21/2018] [Indexed: 11/24/2022] Open
Abstract
Neurovascular and neurometabolic coupling are critical and complex processes underlying brain function. Perturbations in the regulation of these processes are, likely, early dysfunctional alterations in pathological brain aging and age-related neurodegeneration. Evidences support the role of nitric oxide (•NO) as a key messenger both in neurovascular coupling, by signaling from neurons to blood vessels, and in neurometabolic coupling, by modulating O2 utilization by mitochondria. In the present study, we investigated the functionality of neurovascular and neurometabolic coupling in connection to •NO signaling and in association to cognitive performance during aging. For this, we performed in vivo simultaneous measurements of •NO, O2 and cerebral blood flow (CBF) in the hippocampus of F344 rats along chronological age in response to glutamatergic activation and in correlation with cognitive performance. Firstly, it is evidenced the temporal sequence of events upon glutamate stimulation of hippocampal dentate gyrus, encompassing the local and transitory increase of •NO followed by transitory local changes of CBF and pO2. Specifically, the transient increase of •NO is followed by an increase of CBF and biphasic changes of the local pO2. We observed that, although the glutamate-induced •NO dynamics were not significantly affected by aging, the correspondent hemodynamic was progressively diminished accompanying a decline in learning and memory. Noteworthy, in spite of a compromised blood supply, in aged rats we observed an increased ΔpO2 associated to the hemodynamic response, suggestive of a decrease in the global metabolic rate of O2. Furthermore, the impairment in the neurovascular coupling observed along aging in F344 rats was mimicked in young rats by promoting an unbalance in redox status toward oxidation via intracellular generation of superoxide radical. This observation strengthens the idea that oxidative stress may have a critical role in the neurovascular uncoupling underlying brain aging and dysfunction. Overall, data supports an impairment of neurovascular response in connection with cognition decline due to oxidative environment-dependent compromised •NO signaling from neurons to vessels during aging.
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Affiliation(s)
- Cátia F Lourenço
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Ana Ledo
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Miguel Caetano
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Rui M Barbosa
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal
| | - João Laranjinha
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal
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23
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Li Y, Choi WJ, Wei W, Song S, Zhang Q, Liu J, Wang RK. Aging-associated changes in cerebral vasculature and blood flow as determined by quantitative optical coherence tomography angiography. Neurobiol Aging 2018; 70:148-159. [PMID: 30007164 DOI: 10.1016/j.neurobiolaging.2018.06.017] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 06/14/2018] [Accepted: 06/14/2018] [Indexed: 01/29/2023]
Abstract
Normal aging is associated with significant alterations in brain's vascular structure and function, which can lead to compromised cerebral circulation and increased risk of neurodegeneration. The in vivo examination of cerebral blood flow (CBF), including capillary beds, in aging brains with sufficient spatial detail remains challenging with current imaging modalities. In the present study, we use 3-dimensional (3-D) quantitative optical coherence tomography angiography (OCTA) to examine characteristic differences of the cerebral vasculatures and hemodynamics at the somatosensory cortex between old (16 months old) and young mice (2 months old) in vivo. The quantitative metrics include cortical vascular morphology, CBF, and capillary flow velocity. We show that compared with young mice, the pial arterial tortuosity increases by 14%, the capillary vessel density decreases by 15%, and the CBF reduces by 33% in the old mice. Most importantly, changes in capillary velocity and heterogeneity with aging are quantified for the first time with sufficiently high statistical power between young and old populations, with a 21% (p < 0.05) increase in capillary mean velocity and 19% (p ≤ 0.05) increase in velocity heterogeneity in the latter. Our findings through noninvasive imaging are in line with previous studies of vascular structure modification with aging, with additional quantitative assessment in capillary velocity enabled by advanced OCTA algorithms on a single imaging platform. The results offer OCTA as a promising neuroimaging tool to study vascular aging, which may shed new light on the investigations of vascular factors contributing to the pathophysiology of age-related neurodegenerative disorders.
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Affiliation(s)
- Yuandong Li
- Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, WA, USA
| | - Woo June Choi
- Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, WA, USA; School of Electrical and Electronics Engineering, College of ICT Engineering, Chung-Ang University, Seoul, Korea
| | - Wei Wei
- Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, WA, USA
| | - Shaozhen Song
- Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, WA, USA
| | - Qinqin Zhang
- Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, WA, USA
| | - Jialing Liu
- Department of Neurological Surgery, University of California, San Francisco and SFVAMC, San Francisco, CA, USA
| | - Ruikang K Wang
- Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, WA, USA.
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24
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Moeini M, Lu X, Avti PK, Damseh R, Bélanger S, Picard F, Boas D, Kakkar A, Lesage F. Compromised microvascular oxygen delivery increases brain tissue vulnerability with age. Sci Rep 2018; 8:8219. [PMID: 29844478 PMCID: PMC5974237 DOI: 10.1038/s41598-018-26543-w] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 05/16/2018] [Indexed: 11/22/2022] Open
Abstract
Despite the possible role of impaired cerebral tissue oxygenation in age-related cognition decline, much is still unknown about the changes in brain tissue pO2 with age. Using a detailed investigation of the age-related changes in cerebral tissue oxygenation in the barrel cortex of healthy, awake aged mice, we demonstrate decreased arteriolar and tissue pO2 with age. These changes are exacerbated after middle-age. We further uncovered evidence of the presence of hypoxic micro-pockets in the cortex of awake old mice. Our data suggests that from young to middle-age, a well-regulated capillary oxygen supply maintains the oxygen availability in cerebral tissue, despite decreased tissue pO2 next to arterioles. After middle-age, due to decreased hematocrit, reduced capillary density and higher capillary transit time heterogeneity, the capillary network fails to compensate for larger decreases in arterial pO2. The substantial decrease in brain tissue pO2, and the presence of hypoxic micro-pockets after middle-age are of significant importance, as these factors may be related to cognitive decline in elderly people.
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Affiliation(s)
- Mohammad Moeini
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada.,Research Center of Montreal Heart Institute, Montréal, QC, Canada.,Department of Chemistry, McGill University, Montréal, QC, Canada
| | - Xuecong Lu
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada.,Research Center of Montreal Heart Institute, Montréal, QC, Canada
| | - Pramod K Avti
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada.,Research Center of Montreal Heart Institute, Montréal, QC, Canada.,Department of Biophysics, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Rafat Damseh
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada
| | - Samuel Bélanger
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada.,Research Center of Montreal Heart Institute, Montréal, QC, Canada
| | - Frédéric Picard
- Centre de Recherche de l'Institut Universitaire de Cardiologie et Pneumologie de Québec (IUCPQ), Québec, QC, Canada
| | - David Boas
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.,Biomedical Engineering Department, College of Engineering, Boston University, Boston, MA, USA
| | - Ashok Kakkar
- Department of Chemistry, McGill University, Montréal, QC, Canada
| | - Frédéric Lesage
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada. .,Research Center of Montreal Heart Institute, Montréal, QC, Canada.
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25
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Li Y, Wei W, Wang RK. Capillary flow homogenization during functional activation revealed by optical coherence tomography angiography based capillary velocimetry. Sci Rep 2018. [PMID: 29515156 PMCID: PMC5841298 DOI: 10.1038/s41598-018-22513-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Elaborate modeling study suggests an important role of capillary transit time heterogeneity (CTTH) reduction in brain oxygenation during functional hyperemia. Here, we use optical coherence tomography angiography (OCTA) capillary velocimetry to probe blood flow dynamics in cerebral capillary beds and validate the change in CTTH during functional activation in an in vivo rodent model. Through evaluating flow dynamics and consequent transit time parameters from thousands of capillary vessels within three-dimensional (3-D) tissue volume upon hindpaw electrical stimulation, we observe reductions in both capillary mean transit time (MTT) (9.8% ± 2.2) and CTTH (5.9% ± 1.4) in the hindlimb somatosensory cortex (HLS1). Additionally, capillary flow pattern modification is observed with a significant difference (p < 0.05) between the HLS1 and non-activated cortex regions. These quantitative findings reveal a localized microcirculatory adjustment during functional activation, consistent with previous studies, and support the critical contribution of capillary flow homogenization to brain oxygenation. The OCTA velocimetry is a useful tool to image microcirculatory dynamics in vivo using animal models, enabling a more comprehensive understanding as to hemodynamic-metabolic coupling.
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Affiliation(s)
- Yuandong Li
- Department of Bioengineering, University of Washington, Seattle, USA
| | - Wei Wei
- Department of Bioengineering, University of Washington, Seattle, USA
| | - Ruikang K Wang
- Department of Bioengineering, University of Washington, Seattle, USA.
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26
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Ambrose CT. The Role of Capillaries in the Lesser Ailments of Old Age and in Alzheimer's Disease and Vascular Dementia: The Potential of Pro-Therapeutic Angiogenesis. J Alzheimers Dis 2018; 54:31-43. [PMID: 27392865 DOI: 10.3233/jad-160303] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Apart from chronic diseases (arthritis, diabetes, etc.), old age is generally characterized by three lesser ailments: muscle weakness, minor memory lapses, and cold intolerance. This trio of complaints may have a common, underlying cause, namely, the age-associated reduced microcirculation in muscles, brain, skin, and elsewhere in the body. The Angiogenesis Hypothesis proposes that old age is in part a deficiency disease due to the decline in angiogenic (AG) factors, resulting in a reduced capillary density (CD) throughout the body. Over fifty published papers document waning levels of AG factors and/or decreased CD in various organ systems of aged animals and people, including those with Alzheimer's disease. The deficiency of AG factors is analogous to that of certain hormones (e.g., testosterone) whose blood levels also decline with age. In theory, therapeutic angiogenesis employing recombinant AG factors is a tenable treatment for the lesser ailments of old age and may improve the later years of human life. An optimal administration route may be intranasal.
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27
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He X, Wengler K, Schweitzer ME. Diffusion sensitivity of 3D-GRASE in arterial spin labeling perfusion. Magn Reson Med 2018; 80:736-747. [DOI: 10.1002/mrm.27058] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 11/02/2017] [Accepted: 12/05/2017] [Indexed: 12/21/2022]
Affiliation(s)
- Xiang He
- Department of Radiology; Stony Brook University; Stony Brook New York USA
| | - Kenneth Wengler
- Department of Biomedical Engineering; Stony Brook University; Stony Brook New York USA
| | - Mark E. Schweitzer
- Department of Radiology; Stony Brook University; Stony Brook New York USA
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28
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Xu X, Wang B, Ren C, Hu J, Greenberg DA, Chen T, Xie L, Jin K. Age-related Impairment of Vascular Structure and Functions. Aging Dis 2017; 8:590-610. [PMID: 28966804 PMCID: PMC5614324 DOI: 10.14336/ad.2017.0430] [Citation(s) in RCA: 166] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 04/30/2017] [Indexed: 12/12/2022] Open
Abstract
Among age-related diseases, cardiovascular and cerebrovascular diseases are major causes of death. Vascular dysfunction is a key characteristic of these diseases wherein age is an independent and essential risk factor. The present work will review morphological alterations of aging vessels in-depth, which includes the discussion of age-related microvessel loss and changes to vasculature involving the capillary basement membrane, intima, media, and adventitia as well as the accompanying vascular dysfunctions arising from these alterations.
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Affiliation(s)
- Xianglai Xu
- 1Zhongshan Hospital, Fudan University, Shanghai 200032, China.,2Department of Pharmacology and Neuroscience, University of North Texas Health Science Center at Fort Worth, TX 76107, USA
| | - Brian Wang
- 2Department of Pharmacology and Neuroscience, University of North Texas Health Science Center at Fort Worth, TX 76107, USA
| | - Changhong Ren
- 2Department of Pharmacology and Neuroscience, University of North Texas Health Science Center at Fort Worth, TX 76107, USA.,4Institute of Hypoxia Medicine, Xuanwu Hospital, Capital Medical University. Beijing, China
| | - Jiangnan Hu
- 2Department of Pharmacology and Neuroscience, University of North Texas Health Science Center at Fort Worth, TX 76107, USA
| | | | - Tianxiang Chen
- 6Department of Thoracic Surgery, Shanghai Chest Hospital, Shanghai Jiaotong University, Shanghai, China
| | - Liping Xie
- 3Department of Urology, the First Affiliated Hospital, Zhejiang University, Zhejiang Province, China
| | - Kunlin Jin
- 2Department of Pharmacology and Neuroscience, University of North Texas Health Science Center at Fort Worth, TX 76107, USA
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29
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Song Y, Garcia S, Frometa Y, Ramella-Roman JC, Soltani M, Almadi M, Riera JJ, Lin WC. Quantitative assessment of hemodynamic and structural characteristics of in vivo brain tissue using total diffuse reflectance spectrum measured in a non-contact fashion. BIOMEDICAL OPTICS EXPRESS 2017; 8:78-103. [PMID: 28101403 PMCID: PMC5231317 DOI: 10.1364/boe.8.000078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 11/03/2016] [Accepted: 11/08/2016] [Indexed: 05/03/2023]
Abstract
Here we present a new methodology that investigates the intrinsic structural and hemodynamic characteristics of in vivo brain tissue, in a non-contact fashion, and can be easily incorporated in an intra-operative environment. Within this methodology, relative total diffuse reflectance spectra (RTD(λ)) were acquired from targets using a hybrid spectroscopy imaging system. A spectral interpretation algorithm was subsequently applied to RTD(λ) to retrieve optical properties related to the compositional and structural characteristics of each target. Estimation errors of the proposed methodology were computationally evaluated using a Monte Carlo simulation model for photon migration under various conditions. It was discovered that this new methodology could handle moderate noise and achieve very high accuracy, but only if the refractive index of the target is known. The accuracy of the technique was also validated using a series of tissue phantom studies, and consistent and accurate estimates of μs'(λ)/μa(λ) were obtained from all the phantoms tested. Finally, a small-scale animal study was conducted to demonstrate the clinical utility of the reported method, wherein a forepaw stimulation model was utilized to induce transient hemodynamic responses in somatosensory cortices. With this approach, significant stimulation-related changes (p < 0.001) in cortical hemodynamic and structural characteristics were successfully measured.
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30
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Pouliot P, Gagnon L, Lam T, Avti PK, Bowen C, Desjardins M, Kakkar AK, Thorin E, Sakadzic S, Boas DA, Lesage F. Magnetic resonance fingerprinting based on realistic vasculature in mice. Neuroimage 2016; 149:436-445. [PMID: 28043909 DOI: 10.1016/j.neuroimage.2016.12.060] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 11/20/2016] [Accepted: 12/20/2016] [Indexed: 11/26/2022] Open
Abstract
Magnetic resonance fingerprinting (MRF) was recently proposed as a novel strategy for MR data acquisition and analysis. A variant of MRF called vascular MRF (vMRF) followed, that extracted maps of three parameters of physiological importance: cerebral oxygen saturation (SatO2), mean vessel radius and cerebral blood volume (CBV). However, this estimation was based on idealized 2-dimensional simulations of vascular networks using random cylinders and the empirical Bloch equations convolved with a diffusion kernel. Here we focus on studying the vascular MR fingerprint using real mouse angiograms and physiological values as the substrate for the MR simulations. The MR signal is calculated ab initio with a Monte Carlo approximation, by tracking the accumulated phase from a large number of protons diffusing within the angiogram. We first study the identifiability of parameters in simulations, showing that parameters are fully estimable at realistically high signal-to-noise ratios (SNR) when the same angiogram is used for dictionary generation and parameter estimation, but that large biases in the estimates persist when the angiograms are different. Despite these biases, simulations show that differences in parameters remain estimable. We then applied this methodology to data acquired using the GESFIDE sequence with SPIONs injected into 9 young wild type and 9 old atherosclerotic mice. Both the pre injection signal and the ratio of post-to-pre injection signals were modeled, using 5-dimensional dictionaries. The vMRF methodology extracted significant differences in SatO2, mean vessel radius and CBV between the two groups, consistent across brain regions and dictionaries. Further validation work is essential before vMRF can gain wider application.
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Affiliation(s)
- Philippe Pouliot
- Department of Electrical Engineering, Ecole Polytechnique Montreal, Montreal, QC, Canada; Research Centre, Montreal Heart Institute, Montreal, Canada.
| | - Louis Gagnon
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, MA, United States
| | - Tina Lam
- Department of Chemistry, McGill University, Montreal, QC, Canada
| | - Pramod K Avti
- Research Centre, Montreal Heart Institute, Montreal, Canada
| | - Chris Bowen
- Department of Diagnostic Radiology, Dalhousie University, Halifax, NS, Canada
| | - Michèle Desjardins
- Department of Electrical Engineering, Ecole Polytechnique Montreal, Montreal, QC, Canada
| | - Ashok K Kakkar
- Department of Chemistry, McGill University, Montreal, QC, Canada
| | - Eric Thorin
- Dept. of Surgery, Faculty of Medicine, University of Montreal, QC, Canada; Research Centre, Montreal Heart Institute, Montreal, Canada
| | - Sava Sakadzic
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, MA, United States
| | - David A Boas
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, MA, United States
| | - Frédéric Lesage
- Department of Electrical Engineering, Ecole Polytechnique Montreal, Montreal, QC, Canada; Research Centre, Montreal Heart Institute, Montreal, Canada
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31
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Gagnon L, Smith AF, Boas DA, Devor A, Secomb TW, Sakadžić S. Modeling of Cerebral Oxygen Transport Based on In vivo Microscopic Imaging of Microvascular Network Structure, Blood Flow, and Oxygenation. Front Comput Neurosci 2016; 10:82. [PMID: 27630556 PMCID: PMC5006088 DOI: 10.3389/fncom.2016.00082] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 07/25/2016] [Indexed: 01/09/2023] Open
Abstract
Oxygen is delivered to brain tissue by a dense network of microvessels, which actively control cerebral blood flow (CBF) through vasodilation and contraction in response to changing levels of neural activity. Understanding these network-level processes is immediately relevant for (1) interpretation of functional Magnetic Resonance Imaging (fMRI) signals, and (2) investigation of neurological diseases in which a deterioration of neurovascular and neuro-metabolic physiology contributes to motor and cognitive decline. Experimental data on the structure, flow and oxygen levels of microvascular networks are needed, together with theoretical methods to integrate this information and predict physiologically relevant properties that are not directly measurable. Recent progress in optical imaging technologies for high-resolution in vivo measurement of the cerebral microvascular architecture, blood flow, and oxygenation enables construction of detailed computational models of cerebral hemodynamics and oxygen transport based on realistic three-dimensional microvascular networks. In this article, we review state-of-the-art optical microscopy technologies for quantitative in vivo imaging of cerebral microvascular structure, blood flow and oxygenation, and theoretical methods that utilize such data to generate spatially resolved models for blood flow and oxygen transport. These “bottom-up” models are essential for the understanding of the processes governing brain oxygenation in normal and disease states and for eventual translation of the lessons learned from animal studies to humans.
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Affiliation(s)
- Louis Gagnon
- Optics Division, Department of Radiology, MHG/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School Charlestown, MA, USA
| | - Amy F Smith
- Institut de Mécanique des Fluides de ToulouseToulouse, France; Department of Physiology, University of ArizonaTucson, AZ, USA
| | - David A Boas
- Optics Division, Department of Radiology, MHG/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School Charlestown, MA, USA
| | - Anna Devor
- Optics Division, Department of Radiology, MHG/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical SchoolCharlestown, MA, USA; Departments of Neurosciences and Radiology, University of California, San DiegoLa Jolla, CA, USA
| | | | - Sava Sakadžić
- Optics Division, Department of Radiology, MHG/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School Charlestown, MA, USA
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32
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Febo M, Foster TC. Preclinical Magnetic Resonance Imaging and Spectroscopy Studies of Memory, Aging, and Cognitive Decline. Front Aging Neurosci 2016; 8:158. [PMID: 27468264 PMCID: PMC4942756 DOI: 10.3389/fnagi.2016.00158] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Accepted: 06/16/2016] [Indexed: 01/14/2023] Open
Abstract
Neuroimaging provides for non-invasive evaluation of brain structure and activity and has been employed to suggest possible mechanisms for cognitive aging in humans. However, these imaging procedures have limits in terms of defining cellular and molecular mechanisms. In contrast, investigations of cognitive aging in animal models have mostly utilized techniques that have offered insight on synaptic, cellular, genetic, and epigenetic mechanisms affecting memory. Studies employing magnetic resonance imaging and spectroscopy (MRI and MRS, respectively) in animal models have emerged as an integrative set of techniques bridging localized cellular/molecular phenomenon and broader in vivo neural network alterations. MRI methods are remarkably suited to longitudinal tracking of cognitive function over extended periods permitting examination of the trajectory of structural or activity related changes. Combined with molecular and electrophysiological tools to selectively drive activity within specific brain regions, recent studies have begun to unlock the meaning of fMRI signals in terms of the role of neural plasticity and types of neural activity that generate the signals. The techniques provide a unique opportunity to causally determine how memory-relevant synaptic activity is processed and how memories may be distributed or reconsolidated over time. The present review summarizes research employing animal MRI and MRS in the study of brain function, structure, and biochemistry, with a particular focus on age-related cognitive decline.
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Affiliation(s)
- Marcelo Febo
- Department of Psychiatry, William L. and Evelyn F. McKnight Brain Institute, University of Florida Gainesville, FL, USA
| | - Thomas C Foster
- Department of Neuroscience, William L. and Evelyn F. McKnight Brain Institute, University of Florida Gainesville, FL, USA
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33
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Roman S, Merlo A, Duru P, Risso F, Lorthois S. Going beyond 20 μm-sized channels for studying red blood cell phase separation in microfluidic bifurcations. BIOMICROFLUIDICS 2016; 10:034103. [PMID: 27190568 PMCID: PMC4866949 DOI: 10.1063/1.4948955] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 04/27/2016] [Indexed: 05/13/2023]
Abstract
Despite the development of microfluidics, experimental challenges are considerable for achieving a quantitative study of phase separation, i.e., the non-proportional distribution of Red Blood Cells (RBCs) and suspending fluid, in microfluidic bifurcations with channels smaller than 20 μm. Yet, a basic understanding of phase separation in such small vessels is needed for understanding the coupling between microvascular network architecture and dynamics at larger scale. Here, we present the experimental methodologies and measurement techniques developed for that purpose for RBC concentrations (tube hematocrits) ranging between 2% and 20%. The maximal RBC velocity profile is directly measured by a temporal cross-correlation technique which enables to capture the RBC slip velocity at walls with high resolution, highlighting two different regimes (flat and more blunted ones) as a function of RBC confinement. The tube hematocrit is independently measured by a photometric technique. The RBC and suspending fluid flow rates are then deduced assuming the velocity profile of a Newtonian fluid with no slip at walls for the latter. The accuracy of this combination of techniques is demonstrated by comparison with reference measurements and verification of RBC and suspending fluid mass conservation at individual bifurcations. The present methodologies are much more accurate, with less than 15% relative errors, than the ones used in previous in vivo experiments. Their potential for studying steady state phase separation is demonstrated, highlighting an unexpected decrease of phase separation with increasing hematocrit in symmetrical, but not asymmetrical, bifurcations and providing new reference data in regimes where in vitro results were previously lacking.
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34
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Ambrose C. Muscle weakness during aging: a deficiency state involving declining angiogenesis. Ageing Res Rev 2015; 23:139-53. [PMID: 26093038 DOI: 10.1016/j.arr.2015.03.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Revised: 03/19/2015] [Accepted: 03/30/2015] [Indexed: 12/12/2022]
Abstract
This essay begins by proposing that muscle weakness of old age from sarcopenia is due in large part to reduced capillary density in the muscles, as documented in 9 reports of aged persons and animals. Capillary density (CD) is determined by local levels of various angiogenic factors, which also decline in muscles with aging, as reported in 7 studies of old persons and animals. There are also numerous reports of reduced CD in the aged brain and other studies showing reduced CD in the kidney and heart of aged animals. Thus a waning angiogenesis throughout the body may be a natural occurrence in later years and may account significantly for the lesser ailments (physical and cognitive) of elderly people. Old age is regarded here as a deficiency state which may be corrected by therapeutic angiogenesis, much as a hormonal deficiency can be relieved by the appropriate hormone therapy. Such therapy could employ recombinant angiogenic factors which are now commercially available.
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Vandal M, Bourassa P, Calon F. Can insulin signaling pathways be targeted to transport Aβ out of the brain? Front Aging Neurosci 2015; 7:114. [PMID: 26136681 PMCID: PMC4468380 DOI: 10.3389/fnagi.2015.00114] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Accepted: 05/29/2015] [Indexed: 12/11/2022] Open
Abstract
Although the causal role of Amyloid-β (Aβ) in Alzheimer’s disease (AD) is unclear, it is still reasonable to expect that lowering concentrations of Aβ in the brain may decrease the risk of developing the neurocognitive symptoms of the disease. Brain capillary endothelial cells forming the blood-brain barrier (BBB) express transporters regulating the efflux of Aβ out of the cerebral tissue. Age-related BBB dysfunctions, that have been identified in AD patients, might impair Aβ clearance from the brain. Thus, targeting BBB outward transport systems has been suggested as a way to stimulate the clearance of Aβ from the brain. Recent data indicate that the increase in soluble brain Aβ and behavioral impairments in 3×Tg-AD mice generated by months of intake of a high-fat diet can be acutely reversed by the administration of a single dose of insulin. A concomitant increase in plasma Aβ suggests that clearance from the brain through the BBB is a likely mechanism for this rapid effect of insulin. Here, we review how BBB insulin response pathways could be stimulated to decrease brain Aβ concentrations and improve cognitive performance, at least on the short term.
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Affiliation(s)
- Milene Vandal
- Faculté de Pharmacie, Université Laval Quebec, QC, Canada ; Axe Neurosciences, Centre de Recherche du Centre Hospitalier de l'Université Laval (CHUL) Québec, QC, Canada ; Institut des Nutraceutiques et des Aliments Fonctionnels, Université Laval Québec, QC, Canada
| | - Philippe Bourassa
- Faculté de Pharmacie, Université Laval Quebec, QC, Canada ; Axe Neurosciences, Centre de Recherche du Centre Hospitalier de l'Université Laval (CHUL) Québec, QC, Canada ; Institut des Nutraceutiques et des Aliments Fonctionnels, Université Laval Québec, QC, Canada
| | - Frédéric Calon
- Faculté de Pharmacie, Université Laval Quebec, QC, Canada ; Axe Neurosciences, Centre de Recherche du Centre Hospitalier de l'Université Laval (CHUL) Québec, QC, Canada ; Institut des Nutraceutiques et des Aliments Fonctionnels, Université Laval Québec, QC, Canada
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Nanoparticle-mediated growth factor delivery systems: A new way to treat Alzheimer's disease. J Control Release 2015; 206:187-205. [DOI: 10.1016/j.jconrel.2015.03.024] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 03/19/2015] [Accepted: 03/20/2015] [Indexed: 01/03/2023]
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Gagnon L, Sakadžić S, Lesage F, Mandeville ET, Fang Q, Yaseen MA, Boas DA. Multimodal reconstruction of microvascular-flow distributions using combined two-photon microscopy and Doppler optical coherence tomography. NEUROPHOTONICS 2015; 2:015008. [PMID: 26157987 PMCID: PMC4478873 DOI: 10.1117/1.nph.2.1.015008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 02/20/2015] [Indexed: 05/04/2023]
Abstract
Computing microvascular cerebral blood flow ([Formula: see text]) in real cortical angiograms is challenging. Here, we investigated whether the use of Doppler optical coherence tomography (DOCT) flow measurements in individual vessel segments can help in reconstructing [Formula: see text] across the entire vasculature of a truncated cortical angiogram. A [Formula: see text] computational framework integrating DOCT measurements is presented. Simulations performed on a synthetic angiogram showed that the addition of DOCT measurements, especially close to large inflowing or outflowing vessels, reduces the impact of pressure boundary conditions and estimated vessel resistances resulting in a more accurate reconstruction of [Formula: see text]. Our technique was then applied to reconstruct microvascular flow distributions in the mouse cortex down to [Formula: see text] by combining two-photon laser scanning microscopy angiography with DOCT.
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Affiliation(s)
- Louis Gagnon
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Building 149 13th Street, Charlestown, Massachusetts 02129, United States
- Harvard-MIT Division of Health Sciences and Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
- Ecole Polytechnique de Montreal, Department of Electrical Engineering, 2900 Boulevard Edouard-Montpetit, Montreal, Quebec H3T 1J4, Canada
- Address all correspondence to: Louis Gagnon, E-mail:
| | - Sava Sakadžić
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Building 149 13th Street, Charlestown, Massachusetts 02129, United States
| | - Fréderic Lesage
- Ecole Polytechnique de Montreal, Department of Electrical Engineering, 2900 Boulevard Edouard-Montpetit, Montreal, Quebec H3T 1J4, Canada
| | - Emiri T. Mandeville
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Building 149 13th Street, Charlestown, Massachusetts 02129, United States
| | - Qianqian Fang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Building 149 13th Street, Charlestown, Massachusetts 02129, United States
| | - Mohammad A. Yaseen
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Building 149 13th Street, Charlestown, Massachusetts 02129, United States
| | - David A. Boas
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Building 149 13th Street, Charlestown, Massachusetts 02129, United States
- Harvard-MIT Division of Health Sciences and Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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Affiliation(s)
- Sigrid Veasey
- Center for Sleep and Circadian Neurobiology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania Philadelphia, PA
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Desjardins M, Berti R, Pouliot P, Dubeau S, Lesage F. Multimodal study of the hemodynamic response to hypercapnia in anesthetized aged rats. Neurosci Lett 2014; 563:33-7. [PMID: 24480251 DOI: 10.1016/j.neulet.2014.01.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 01/13/2014] [Accepted: 01/17/2014] [Indexed: 10/25/2022]
Abstract
With aging, the brain undergoes changes in metabolism and perfusion, both of which influence the widely used blood-oxygenation-level-dependent (BOLD) MRI signal. To isolate the vascular effects associated with age, this study measured the response to a hypercapnic challenge using different imaging modalities in 19 young (3 months-old) and 13 old (24 months-old) Long-Evans rats. Intrinsic optical imaging was used to measure oxy (HbO), deoxy (HbR) and total (HbT) hemoglobin concentration changes, laser speckle for cerebral blood flow (CBF) changes, and MRI for the BOLD signal. Older rats had smaller HbO (41% smaller), HbT (50%) and CBF (34%) responses, but the temporal dynamics did not exhibit significant age differences. The ratio of CBV to CBF responses was also smaller in older adults, potentially indicating a change in the compliance of vessels.
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Affiliation(s)
- Michèle Desjardins
- Institut de Génie Biomédical, Dpt. de Génie Électrique, École Polytechnique de Montréal, C.P. 6079, succ. Centre-ville, Montréal, QC, H3C 3A7, Canada; Montreal Heart Institute, 5000 rue Bélanger, Montréal, QC, H1T 1C8, Canada.
| | - Romain Berti
- Institut de Génie Biomédical, Dpt. de Génie Électrique, École Polytechnique de Montréal, C.P. 6079, succ. Centre-ville, Montréal, QC, H3C 3A7, Canada; Montreal Heart Institute, 5000 rue Bélanger, Montréal, QC, H1T 1C8, Canada
| | - Philippe Pouliot
- Institut de Génie Biomédical, Dpt. de Génie Électrique, École Polytechnique de Montréal, C.P. 6079, succ. Centre-ville, Montréal, QC, H3C 3A7, Canada; Montreal Heart Institute, 5000 rue Bélanger, Montréal, QC, H1T 1C8, Canada
| | - Simon Dubeau
- Institut de Génie Biomédical, Dpt. de Génie Électrique, École Polytechnique de Montréal, C.P. 6079, succ. Centre-ville, Montréal, QC, H3C 3A7, Canada; Montreal Heart Institute, 5000 rue Bélanger, Montréal, QC, H1T 1C8, Canada
| | - Frédéric Lesage
- Institut de Génie Biomédical, Dpt. de Génie Électrique, École Polytechnique de Montréal, C.P. 6079, succ. Centre-ville, Montréal, QC, H3C 3A7, Canada; Montreal Heart Institute, 5000 rue Bélanger, Montréal, QC, H1T 1C8, Canada
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