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Nagasawa T, Iwata K, Bachour RPDS, Ogawa-Ochiai K, Tsumura N, Cardoso GC. Quantitative Capillary Refill Time with image-based finger force estimation. Med Eng Phys 2024; 127:104168. [PMID: 38692764 DOI: 10.1016/j.medengphy.2024.104168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Revised: 02/28/2024] [Accepted: 04/10/2024] [Indexed: 05/03/2024]
Abstract
Skin color observation provides a simple and non-invasive method to estimate the health status of patients. Capillary Refill Time (CRT) is widely used as an indicator of pathophysiological conditions, especially in emergency patients. While the measurement of CRT is easy to perform, its evaluation is highly subjective. This study proposes a method to aid quantified CRT measurement using an RGB camera. The procedure consists in applying finger compression to the forearm, and the CRT is calculated based on the skin color change after the pressure release. We estimate compression applied by a finger from its fingernail color change during compression. Our study shows a step towards camera-based quantitative CRT for untrained individuals.
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Affiliation(s)
- Takumi Nagasawa
- Department of Imaging Science, Graduate School of Science and Engineering, Chiba University, Chiba, 263-8522, Japan
| | - Kazuki Iwata
- Department of Imaging Science, Graduate School of Science and Engineering, Chiba University, Chiba, 263-8522, Japan.
| | | | - Keiko Ogawa-Ochiai
- Kampo Clinical Center, Hiroshima University Hospital, Hiroshima, 734-8551, Japan
| | - Norimichi Tsumura
- Department of Imaging Sciences, Graduate School of Engineering, Chiba University, Chiba, 263-8522, Japan
| | - George C Cardoso
- Physics Department, FFCLRP, University of Sao Paulo, 14040-901, Brazil
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2
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Parry HA, Willingham TB, Giordano KA, Kim Y, Qazi S, Knutson JR, Combs CA, Glancy B. Impact of capillary and sarcolemmal proximity on mitochondrial structure and energetic function in skeletal muscle. J Physiol 2024; 602:1967-1986. [PMID: 38564214 PMCID: PMC11068488 DOI: 10.1113/jp286246] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 03/08/2024] [Indexed: 04/04/2024] Open
Abstract
Mitochondria within skeletal muscle cells are located either between the muscle contractile apparatus (interfibrillar mitochondria, IFM) or beneath the cell membrane (subsarcolemmal mitochondria, SSM), with several structural and functional differences reported between IFM and SSM. However, recent 3D imaging studies demonstrate that mitochondria are particularly concentrated in the proximity of capillaries embedded in sarcolemmal grooves rather than in proximity to the sarcolemma itself (paravascular mitochondria, PVM). To evaluate the impact of capillary vs. sarcolemmal proximity, we compared the structure and function of skeletal muscle mitochondria located either lateral to embedded capillaries (PVM), adjacent to the sarcolemma but not in PVM pools (SSM) or interspersed between sarcomeres (IFM). Mitochondrial morphology and interactions were assessed by 3D electron microscopy coupled with machine learning segmentation, whereas mitochondrial energy conversion was assessed by two-photon microscopy of mitochondrial membrane potential, content, calcium, NADH redox and flux in live, intact cells. Structurally, although PVM and SSM were similarly larger than IFM, PVM were larger, rounder and had more physical connections to neighbouring mitochondria compared to both IFM and SSM. Functionally, PVM had similar or greater basal NADH flux compared to SSM and IFM, respectively, despite a more oxidized NADH pool and a greater membrane potential, signifying a greater activation of the electron transport chain in PVM. Together, these data indicate that proximity to capillaries has a greater impact on resting mitochondrial energy conversion and distribution in skeletal muscle than the sarcolemma alone. KEY POINTS: Capillaries have a greater impact on mitochondrial energy conversion in skeletal muscle than the sarcolemma. Paravascular mitochondria are larger, and the outer mitochondrial membrane is more connected with neighbouring mitochondria. Interfibrillar mitochondria are longer and have greater contact sites with other organelles (i.e. sarcoplasmic reticulum and lipid droplets). Paravascular mitochondria have greater activation of oxidative phosphorylation than interfibrillar mitochondria at rest, although this is not regulated by calcium.
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Affiliation(s)
- Hailey A. Parry
- National Lung, Blood, and Heart Institute, National Institutes of Health, Bethesda, MD, USA
| | - T. Bradley Willingham
- National Lung, Blood, and Heart Institute, National Institutes of Health, Bethesda, MD, USA
- Shephard Center’s Virginia C. Crawford Research Institute, Atlanta, GA, USA
| | | | - Yuho Kim
- National Lung, Blood, and Heart Institute, National Institutes of Health, Bethesda, MD, USA
- University of Massachusetts, Lowell, MA,USA
| | - Shureed Qazi
- National Lung, Blood, and Heart Institute, National Institutes of Health, Bethesda, MD, USA
| | - Jay R. Knutson
- National Lung, Blood, and Heart Institute, National Institutes of Health, Bethesda, MD, USA
| | - Christian A. Combs
- National Lung, Blood, and Heart Institute, National Institutes of Health, Bethesda, MD, USA
| | - Brian Glancy
- National Lung, Blood, and Heart Institute, National Institutes of Health, Bethesda, MD, USA
- National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, USA
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3
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Poole DC. Oxygen's final frontier: novel capillary-mitochondrial relationships in muscle predicate function. J Physiol 2024; 602:1879-1880. [PMID: 38564190 DOI: 10.1113/jp286550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Accepted: 03/22/2024] [Indexed: 04/04/2024] Open
Affiliation(s)
- David C Poole
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, KS, USA
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4
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Kowalewska PM, Milkovich SL, Goldman D, Sandow SL, Ellis CG, Welsh DG. Capillary oxygen regulates demand-supply coupling by triggering connexin40-mediated conduction: Rethinking the metabolic hypothesis. Proc Natl Acad Sci U S A 2024; 121:e2303119121. [PMID: 38349880 PMCID: PMC10895355 DOI: 10.1073/pnas.2303119121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Accepted: 12/21/2023] [Indexed: 02/15/2024] Open
Abstract
Coupling red blood cell (RBC) supply to O2 demand is an intricate process requiring O2 sensing, generation of a stimulus, and signal transduction that alters upstream arteriolar tone. Although actively debated, this process has been theorized to be induced by hypoxia and to involve activation of endothelial inwardly rectifying K+ channels (KIR) 2.1 by elevated extracellular K+ to trigger conducted hyperpolarization via connexin40 (Cx40) gap junctions to upstream resistors. This concept was tested in resting healthy skeletal muscle of Cx40-/- and endothelial KIR2.1-/- mice using state-of-the-art live animal imaging where the local tissue O2 environment was manipulated using a custom gas chamber. Second-by-second capillary RBC flow responses were recorded as O2 was altered. A stepwise drop in PO2 at the muscle surface increased RBC supply in capillaries of control animals while elevated O2 elicited the opposite response; capillaries were confirmed to express Cx40. The RBC flow responses were rapid and tightly coupled to O2; computer simulations did not support hypoxia as a driving factor. In contrast, RBC flow responses were significantly diminished in Cx40-/- mice. Endothelial KIR2.1-/- mice, on the other hand, reacted normally to O2 changes, even when the O2 challenge was targeted to a smaller area of tissue with fewer capillaries. Conclusively, microvascular O2 responses depend on coordinated electrical signaling via Cx40 gap junctions, and endothelial KIR2.1 channels do not initiate the event. These findings reconceptualize the paradigm of blood flow regulation in skeletal muscle and how O2 triggers this process in capillaries independent of extracellular K+.
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Affiliation(s)
- Paulina M Kowalewska
- Robarts Research Institute, University of Western Ontario, London, ON N6A 5B7, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON N6A 5B7, Canada
| | - Stephanie L Milkovich
- Robarts Research Institute, University of Western Ontario, London, ON N6A 5B7, Canada
| | - Daniel Goldman
- Department of Medical Biophysics, University of Western Ontario, London, ON N6A 5B7, Canada
| | - Shaun L Sandow
- School of Health, University of the Sunshine Coast, Maroochydore, QLD 4556, Australia
- School of Clinical Medicine, University of Queensland, St. Lucia, QLD 4072, Australia
| | - Christopher G Ellis
- Robarts Research Institute, University of Western Ontario, London, ON N6A 5B7, Canada
- Department of Medical Biophysics, University of Western Ontario, London, ON N6A 5B7, Canada
| | - Donald G Welsh
- Robarts Research Institute, University of Western Ontario, London, ON N6A 5B7, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON N6A 5B7, Canada
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Maqbool K, Siddiqui AM, Mehboob H, Jamil Q. Mechanical study of blood flow through a permeable capillary with slippery wall. J Mech Behav Biomed Mater 2024; 150:106265. [PMID: 38035644 DOI: 10.1016/j.jmbbm.2023.106265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 11/18/2023] [Accepted: 11/20/2023] [Indexed: 12/02/2023]
Abstract
This research presents the mechanical behavior of blood flow through capillary having smooth inner surface. In this study modelling of blood flow via permeable and lubricated capillary caused by nutrients re-absorption has been done by the help of laws of momentum and mass. The nutrients re-absorption is assumed to be constant and inner walls of the capillary are smooth and slippery therefore slip condition on the velocity and constant rate in vertical direction at the wall has considered. The Kelvin Voigt model is employed to simulate blood flow via capillaries, and results for pressure, blood flow pattern, and shear force necessary for blood flow are discovered by recursive approach. Numerical results for nutrient re-absorption from the blood and impact of smooth and slippery surfaces on blood flow are shown through graphs. The novelty of the research invents that the smoothness and slickness of capillary wall is a crucial presumption to examine the blood as non-Newtonian fluid via capillary.
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Affiliation(s)
- K Maqbool
- Department of Mathematics, Pennsylvania State University, York Campus, 1031 Edgecomb Avenue, York, PA, 17403, USA; Department of Mathematics & Statistics, International Islamic University, Islamabad, 44000, Pakistan.
| | - A M Siddiqui
- Department of Mathematics, Pennsylvania State University, York Campus, 1031 Edgecomb Avenue, York, PA, 17403, USA
| | - H Mehboob
- Department of Mathematics & Statistics, International Islamic University, Islamabad, 44000, Pakistan
| | - Q Jamil
- Department of Mathematics & Statistics, International Islamic University, Islamabad, 44000, Pakistan
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Hirth E, Cao W, Peltonen M, Kapetanovic E, Dietsche C, Svanberg S, Filippova M, Reddy S, Dittrich PS. Self-assembled and perfusable microvasculature-on-chip for modeling leukocyte trafficking. Lab Chip 2024; 24:292-304. [PMID: 38086670 PMCID: PMC10793075 DOI: 10.1039/d3lc00719g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 11/20/2023] [Indexed: 01/18/2024]
Abstract
Leukocyte recruitment from blood to tissue is a process that occurs at the level of capillary vessels during both physiological and pathological conditions. This process is also relevant for evaluating novel adoptive cell therapies, in which the trafficking of therapeutic cells such as chimeric antigen receptor (CAR)-T cells throughout the capillaries of solid tumors is important. Local variations in blood flow, mural cell concentration, and tissue stiffness contribute to the regulation of capillary vascular permeability and leukocyte trafficking throughout the capillary microvasculature. We developed a platform to mimic a biologically functional human arteriole-venule microcirculation system consisting of pericytes (PCs) and arterial and venous primary endothelial cells (ECs) embedded within a hydrogel, which self-assembles into a perfusable, heterogeneous microvasculature. Our device shows a preferential association of PCs with arterial ECs that drives the flow-dependent formation of microvasculature networks. We show that PCs stimulate basement membrane matrix synthesis, which affects both vessel diameter and permeability in a manner correlating with the ratio of ECs to PCs. Moreover, we demonstrate that hydrogel concentration can affect capillary morphology but has no observed effect on vascular permeability. The biological function of our capillary network was demonstrated using an inflammation model, where significantly higher expression of cytokines, chemokines, and adhesion molecules was observed after tumor necrosis factor-alpha (TNF-α) treatment. Accordingly, T cell adherence and transendothelial migration were significantly increased in the immune-activated state. Taken together, our platform allows the generation of a perfusable microvasculature that recapitulates the structure and function of an in vivo capillary bed that can be used as a model for developing potential immunotherapies.
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Affiliation(s)
- Elisabeth Hirth
- Department of Biosystems Science and Engineering, ETH Zurich, 4056, Basel, Switzerland.
| | - Wuji Cao
- Department of Biosystems Science and Engineering, ETH Zurich, 4056, Basel, Switzerland.
| | - Marina Peltonen
- Department of Biosystems Science and Engineering, ETH Zurich, 4056, Basel, Switzerland.
| | - Edo Kapetanovic
- Department of Biosystems Science and Engineering, ETH Zurich, 4056, Basel, Switzerland.
| | - Claudius Dietsche
- Department of Biosystems Science and Engineering, ETH Zurich, 4056, Basel, Switzerland.
| | - Sara Svanberg
- Department of Biosystems Science and Engineering, ETH Zurich, 4056, Basel, Switzerland.
| | - Maria Filippova
- Department of Biomedicine, University of Basel, 4031 Basel, Switzerland
| | - Sai Reddy
- Department of Biosystems Science and Engineering, ETH Zurich, 4056, Basel, Switzerland.
| | - Petra S Dittrich
- Department of Biosystems Science and Engineering, ETH Zurich, 4056, Basel, Switzerland.
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Hu NW, Lomel BM, Rice EW, Hossain MMN, Sarntinoranont M, Secomb TW, Murfee WL, Balogh P. Estimation of shear stress heterogeneity along capillary segments in angiogenic rat mesenteric microvascular networks. Microcirculation 2023; 30:e12830. [PMID: 37688531 DOI: 10.1111/micc.12830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 08/22/2023] [Accepted: 08/28/2023] [Indexed: 09/11/2023]
Abstract
OBJECTIVE Fluid shear stress is thought to be a regulator of endothelial cell behavior during angiogenesis. The link, however, requires an understanding of stress values at the capillary level in angiogenic microvascular networks. Critical questions remain. What are the stresses? Do capillaries experience similar stress magnitudes? Can variations explain vessel-specific behavior? The objective of this study was to estimate segment-specific shear stresses in angiogenic networks. METHODS Images of angiogenic networks characterized by increased vascular density were obtained from rat mesenteric tissues stimulated by compound 48/80-induced mast cell degranulation. Vessels were identified by perfusion of a 40 kDa fixable dextran prior to harvesting and immunolabeling for PECAM. Using a network flow-based segment model with physiologically relevant parameters, stresses were computed per vessel for regions across multiple networks. RESULTS Stresses ranged from 0.003 to 2328.1 dyne/cm2 and varied dramatically at the capillary level. For all regions, the maximum segmental shear stresses were for capillary segments. Stresses along proximal capillaries branching from arteriole inlets were increased compared to stresses along capillaries in more distal regions. CONCLUSIONS The results highlight the variability of shear stresses along angiogenic capillaries and motivate new discussions on how endothelial cells may respond in vivo to segment-specific microenvironment during angiogenesis.
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Affiliation(s)
- Nien-Wen Hu
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Florida, Gainesville, USA
| | - Banks M Lomel
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Florida, Gainesville, USA
| | - Elijah W Rice
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Florida, Gainesville, USA
| | - Mir Md Nasim Hossain
- Department of Mechanical and Industrial Engineering, New Jersey Institute of Technology, New Jersey, Newark, USA
| | - Malisa Sarntinoranont
- Department of Mechanical and Aerospace Engineering, University of Florida, Florida, Gainesville, USA
| | - Timothy W Secomb
- Department of Physiology, University of Arizona, Arizona, Tucson, USA
| | - Walter L Murfee
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Florida, Gainesville, USA
| | - Peter Balogh
- Department of Mechanical and Industrial Engineering, New Jersey Institute of Technology, New Jersey, Newark, USA
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Margolis EA, Friend NE, Rolle MW, Alsberg E, Putnam AJ. Manufacturing the multiscale vascular hierarchy: progress toward solving the grand challenge of tissue engineering. Trends Biotechnol 2023; 41:1400-1416. [PMID: 37169690 PMCID: PMC10593098 DOI: 10.1016/j.tibtech.2023.04.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 04/05/2023] [Accepted: 04/14/2023] [Indexed: 05/13/2023]
Abstract
In human vascular anatomy, blood flows from the heart to organs and tissues through a hierarchical vascular tree, comprising large arteries that branch into arterioles and further into capillaries, where gas and nutrient exchange occur. Engineering a complete, integrated vascular hierarchy with vessels large enough to suture, strong enough to withstand hemodynamic forces, and a branching structure to permit immediate perfusion of a fluidic circuit across scales would be transformative for regenerative medicine (RM), enabling the translation of engineered tissues of clinically relevant size, and perhaps whole organs. How close are we to solving this biological plumbing problem? In this review, we highlight advances in engineered vasculature at individual scales and focus on recent strategies to integrate across scales.
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Affiliation(s)
- Emily A Margolis
- University of Michigan, Department of Biomedical Engineering, Ann Arbor, MI, USA
| | - Nicole E Friend
- University of Michigan, Department of Biomedical Engineering, Ann Arbor, MI, USA
| | - Marsha W Rolle
- Worcester Polytechnic Institute, Department of Biomedical Engineering, Worcester, MA, USA
| | - Eben Alsberg
- University of Illinois at Chicago, Department of Biomedical Engineering, Chicago, IL, USA
| | - Andrew J Putnam
- University of Michigan, Department of Biomedical Engineering, Ann Arbor, MI, USA.
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Williams DA, Flood MH. Hematoloechus sp. attachment shifts endothelium in vivo from pro- to anti-inflammatory profile in Rana pipiens: evidence from systemic and capillary physiology. Am J Physiol Regul Integr Comp Physiol 2023; 325:R133-R153. [PMID: 37272786 PMCID: PMC10393331 DOI: 10.1152/ajpregu.00041.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 05/30/2023] [Accepted: 05/31/2023] [Indexed: 06/06/2023]
Abstract
This prospective, descriptive study focused on lung flukes (Hematoloechus sp., H) and their impact on systemic and individual capillary variables measured in pithed Rana pipiens, a long-standing model for studies of capillary physiology. Three groups were identified based on Hematoloechus attachment: no Hematoloechus (No H), Hematoloechus not attached (H Not Att), and Hematoloechus attached (H Att). Among 38 descriptive, cardiovascular, and immunological variables, 18 changed significantly with H. Symptoms of H included weight loss, elevated immune cells, heart rate variability, faster coagulation, lower hematocrit, and fluid accumulation. Important capillary function discoveries included median baselines for hydraulic conductivity (Lp) of 7.0 (No H), 12.4 (H Not Att), and 4.2 (H Att) × 10-7 cm·s-1·cmH2O-1 (P < 0.0001) plus seasonal adaptation of sigma delta pi [σ(πc-πi), P = 0.03]. Pro- and anti-inflammatory phases were revealed for Lp and plasma nitrite/nitrate concentration ([NOx]) in both H Not Att and H Att, whereas capillary wall tensile strength increased in the H Att. H attachment was advantageous for the host due to lower edema and for the parasite via a sustained food source illustrating an excellent example of natural symbiosis. However, H attachment also resulted in host weight loss: in time, a conundrum for the highly dependent parasite. The study increases overall knowledge of Rana pipiens by revealing intriguing effects of H and previously unknown, naturally occurring seasonal changes in many variables. The data improve Rana pipiens as a general scientific and capillary physiology model. Diseases of inflammation and stroke are among the clinical applications.
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Affiliation(s)
- Donna A Williams
- College of Nursing, Montana State University, Bozeman, Montana, United States
| | - Mary H Flood
- College of Nursing, Montana State University, Bozeman, Montana, United States
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10
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Neriyanuri S, Bedggood P, Symons RCA, Metha AB. Flow Heterogeneity and Factors Contributing to the Variability in Retinal Capillary Blood Flow. Invest Ophthalmol Vis Sci 2023; 64:15. [PMID: 37450310 DOI: 10.1167/iovs.64.10.15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/18/2023] Open
Abstract
Purpose Capillary flow plays an important role in the nourishment and maintenance of healthy neural tissue and can be observed directly and non-invasively in the living human retina. Despite their importance, patterns of normal capillary flow are not well understood due to limitations in spatial and temporal resolution of imaging data. Methods Capillary flow characteristics were studied in the retina of three healthy young individuals using a high-resolution adaptive optics ophthalmoscope. Imaging with frame rates of 200 to 300 frames per second was sufficient to capture details of the single-file flow of red blood cells in capillaries over the course of about 3 seconds. Results Erythrocyte velocities were measured from 72 neighboring vessels of the parafoveal capillary network for each subject. We observed strong variability among vessels within a given subject, and even within a given imaged field, across a range of capillary flow parameters including maximum and minimum velocities, pulsatility, abruptness of the systolic peak, and phase of the cardiac cycle. The observed variability was not well explained by "local" factors such as the vessel diameter, tortuosity, length, linear cell density, or hematocrit of the vessel. Within a vessel, a moderate relation between the velocities and hematocrit was noted, suggesting a redistribution of plasma between cells with changes in flow. Conclusions These observations advance our fundamental understanding of normal capillary physiology and raise questions regarding the potential role of network-level effects in explaining the observed flow heterogeneity.
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Affiliation(s)
- Srividya Neriyanuri
- Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Phillip Bedggood
- Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - R C Andrew Symons
- Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia
- Department of Surgery, The University of Melbourne, Parkville, Victoria, Australia
- Centre for Eye Research Australia, East Melbourne, Victoria, Australia
- Department of Surgery, Alfred Hospital, Monash University, Melbourne, Victoria, Australia
| | - Andrew B Metha
- Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia
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Korte N, James G, You H, Hirunpattarasilp C, Christie I, Sethi H, Attwell D. Noradrenaline released from locus coeruleus axons contracts cerebral capillary pericytes via α2 adrenergic receptors. J Cereb Blood Flow Metab 2023; 43:1142-1152. [PMID: 36688515 PMCID: PMC10291462 DOI: 10.1177/0271678x231152549] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 11/15/2022] [Accepted: 01/03/2023] [Indexed: 01/24/2023]
Abstract
Noradrenaline (NA) release from locus coeruleus axons generates vascular contractile tone in arteriolar smooth muscle and contractile capillary pericytes. This tone allows neuronal activity to evoke vasodilation that increases local cerebral blood flow (CBF). Much of the vascular resistance within the brain is located in capillaries and locus coeruleus axons have NA release sites closer to pericytes than to arterioles. In acute brain slices, NA contracted pericytes but did not raise the pericyte cytoplasmic Ca2+ concentration, while the α1 agonist phenylephrine did not evoke contraction. Blocking α2 adrenergic receptors (α2Rs, which induce contraction by inhibiting cAMP production), greatly reduced the NA-evoked pericyte contraction, whereas stimulating α2Rs using xylazine (a sedative) or clonidine (an anti-hypertensive drug) evoked pericyte contraction. Noradrenaline-evoked pericyte contraction and capillary constriction are thus mediated via α2Rs. Consequently, α2Rs may not only modulate CBF in health and pathological conditions, but also contribute to CBF changes evoked by α2R ligands administered in research, veterinary and clinical settings.
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Affiliation(s)
- Nils Korte
- Dept of Neuroscience, Physiology & Pharmacology, University College London, London, UK
| | - Greg James
- Dept of Neuroscience, Physiology & Pharmacology, University College London, London, UK
- Department of Neurosurgery, Great Ormond Street Hospital, London, UK
| | - Haoming You
- Dept of Neuroscience, Physiology & Pharmacology, University College London, London, UK
| | - Chanawee Hirunpattarasilp
- Dept of Neuroscience, Physiology & Pharmacology, University College London, London, UK
- Princess Srisavangavadhana College of Medicine, Chulabhorn Royal Academy, Bangkok, Thailand
| | - Isabel Christie
- Dept of Neuroscience, Physiology & Pharmacology, University College London, London, UK
| | - Huma Sethi
- Dept of Neurosurgery, National Hospital for Neurology and Neurosurgery, London, UK
| | - David Attwell
- Dept of Neuroscience, Physiology & Pharmacology, University College London, London, UK
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Davis H, Attwell D. A tight squeeze: how do we make sense of small changes in microvascular diameter? J Physiol 2023; 601:2263-2272. [PMID: 37036208 PMCID: PMC10953087 DOI: 10.1113/jp284207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 04/04/2023] [Indexed: 04/11/2023] Open
Abstract
The brain is an energetically demanding tissue which, to function adequately, requires constant fine tuning of its supporting blood flow, and hence energy supply. Whilst blood flow was traditionally believed to be regulated only by vascular smooth muscle cells on arteries and arterioles supplying the brain, recent work has suggested a critical role for capillary pericytes, which are also contractile. This concept has evoked some controversy, especially over the relative contributions of arterioles and capillaries to the control of cerebral blood flow. Here we outline why pericytes are in a privileged position to control cerebral blood flow. First we discuss the evidence, and fundamental equations, which describe how the small starting diameter of capillaries, compared to upstream arterioles, confers a potentially greater control by capillary pericytes than by arterioles over total cerebral vascular resistance. Then we suggest that the faster time frame over which low branch order capillary pericytes dilate in response to local energy demands provides a niche role for pericytes to regulate blood flow compared to slower responding arterioles. Finally, we discuss the role of pericytes in capillary stalling, whereby pericyte contraction appears to facilitate a transient stall of circulating blood cells, exacerbating the effect of pericytes upon cerebral blood flow.
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Affiliation(s)
- Harvey Davis
- Department of Neuroscience, Physiology & PharmacologyUniversity College LondonLondonUK
| | - David Attwell
- Department of Neuroscience, Physiology & PharmacologyUniversity College LondonLondonUK
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Suzuki H, Takeda H, Takuwa H, Ji B, Higuchi M, Kanno I, Masamoto K. Capillary responses to functional and pathological activations rely on the capillary states at rest. J Cereb Blood Flow Metab 2023; 43:1010-1024. [PMID: 36752020 PMCID: PMC10196750 DOI: 10.1177/0271678x231156372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 01/09/2023] [Accepted: 01/19/2023] [Indexed: 02/09/2023]
Abstract
Brain capillaries play a crucial role in maintaining cellular viability and thus preventing neurodegeneration. The aim of this study was to characterize the brain capillary morphology at rest and during neural activation based on a big data analysis from three-dimensional microangiography. Neurovascular responses were measured using a genetic calcium sensor expressed in neurons and microangiography with two-photon microscopy, while neural acivity was modulated by stimulation of contralateral whiskers or by a seizure evoked by kainic acid. For whisker stimulation, 84% of the capillary sites showed no detectable diameter change. The remaining 10% and 6% were dilated and constricted, respectively. Significant differences were observed for capillaries in the diameter at rest between the locations of dilation and constriction. Even the seizures resulted in 44% of the capillaries having no detectable change in diameter, while 56% of the capillaries dilated. The extent of dilation was dependent on the diameter at rest. In conclusion, big data analysis on brain capillary morphology has identified at least two types of capillary states: capillaries with diameters that are relatively large at rest and stable over time regardless of neural activity and capillaries whose diameters are relatively small at rest and vary according to neural activity.
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Affiliation(s)
- Hiroki Suzuki
- Graduate School of
Informatics and Engineering, University of Electro-Communications,
Tokyo, Japan
| | - Hiroshi Takeda
- Graduate School of
Informatics and Engineering, University of Electro-Communications,
Tokyo, Japan
| | - Hiroyuki Takuwa
- Department of Functional
Brain Imaging, National Institutes for Quantum Science and Technology,
Chiba, Japan
| | - Bin Ji
- Department of Functional
Brain Imaging, National Institutes for Quantum Science and Technology,
Chiba, Japan
- Department of Radiopharmacy
and Molecular Imaging, School of Pharmacy, Fudan University, Shanghai,
China
| | - Makoto Higuchi
- Department of Functional
Brain Imaging, National Institutes for Quantum Science and Technology,
Chiba, Japan
| | - Iwao Kanno
- Department of Functional
Brain Imaging, National Institutes for Quantum Science and Technology,
Chiba, Japan
| | - Kazuto Masamoto
- Graduate School of
Informatics and Engineering, University of Electro-Communications,
Tokyo, Japan
- Department of Functional
Brain Imaging, National Institutes for Quantum Science and Technology,
Chiba, Japan
- Center for Neuroscience and
Biomedical Engineering, University of Electro-Communications, Tokyo,
Japan
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14
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Kissane RWP, Hauton D, Tickle PG, Egginton S. Skeletal muscle adaptation to indirect electrical stimulation: divergence between microvascular and metabolic adaptations. Exp Physiol 2023; 108:891-911. [PMID: 37026596 PMCID: PMC10988499 DOI: 10.1113/ep091134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 03/15/2023] [Indexed: 04/08/2023]
Abstract
NEW FINDINGS What is the central question of this study? Can we manipulate muscle recruitment to differentially enhance skeletal muscle fatigue resistance? What is the main finding and its importance? Through manipulation of muscle activation patterns, it is possible to promote distinct microvascular growth. Enhancement of fatigue resistance is closely associated with the distribution of the capillaries within the muscle, not necessarily with quantity. Additionally, at the acute stages of remodelling in response to indirect electrical stimulation, the improvement in fatigue resistance appears to be primarily driven by vascular remodelling, with metabolic adaptation of secondary importance. ABSTRACT Exercise involves a complex interaction of factors influencing muscle performance, where variations in recruitment pattern (e.g., endurance vs. resistance training) may differentially modulate the local tissue environment (i.e., oxygenation, blood flow, fuel utilization). These exercise stimuli are potent drivers of vascular and metabolic change. However, their relative contribution to adaptive remodelling of skeletal muscle and subsequent performance is unclear. Using implantable devices, indirect electrical stimulation (ES) of locomotor muscles of rat at different pacing frequencies (4, 10 and 40 Hz) was used to differentially recruit hindlimb blood flow and modulate fuel utilization. After 7 days, ES promoted significant remodelling of microvascular composition, increasing capillary density in the cortex of the tibialis anterior by 73%, 110% and 55% for the 4 Hz, 10 and 40 Hz groups, respectively. Additionally, there was remodelling of the whole muscle metabolome, including significantly elevated amino acid turnover, with muscle kynurenic acid levels doubled by pacing at 10 Hz (P < 0.05). Interestingly, the fatigue index of skeletal muscle was only significantly elevated in 10 Hz (58% increase) and 40 Hz (73% increase) ES groups, apparently linked to improved capillary distribution. These data demonstrate that manipulation of muscle recruitment pattern may be used to differentially expand the capillary network prior to altering the metabolome, emphasising the importance of local capillary supply in promoting exercise tolerance.
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Affiliation(s)
- Roger W. P. Kissane
- Department of Musculoskeletal & Ageing Science, Faculty of Health & Life SciencesUniversity of LiverpoolLiverpoolUK
- School of Biomedical Sciences, Faculty of BiosciencesUniversity of LeedsLeedsUK
| | - David Hauton
- Metabolomics Research Group, Department of ChemistryUniversity of OxfordOxfordUK
| | - Peter G. Tickle
- School of Biomedical Sciences, Faculty of BiosciencesUniversity of LeedsLeedsUK
| | - Stuart Egginton
- School of Biomedical Sciences, Faculty of BiosciencesUniversity of LeedsLeedsUK
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15
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Mughal A, Nelson MT, Hill-Eubanks D. The post-arteriole transitional zone: a specialized capillary region that regulates blood flow within the CNS microvasculature. J Physiol 2023; 601:889-901. [PMID: 36751860 PMCID: PMC9992301 DOI: 10.1113/jp282246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 01/13/2023] [Indexed: 02/09/2023] Open
Abstract
The brain is an energy hog, consuming available energy supplies at a rate out of all proportion to its relatively small size. This outsized demand, largely reflecting the unique computational activity of the brain, is met by an ensemble of neurovascular coupling mechanisms that link neuronal activity with local increases in blood delivery. This just-in-time replenishment strategy, made necessary by the limited energy-storage capacity of neurons, complicates the nutrient-delivery task of the cerebral vasculature, layering on a temporo-spatial requirement that invites - and challenges - mechanistic interpretation. The centre of gravity of research efforts to disentangle these mechanisms has shifted from an initial emphasis on astrocyte-arteriole-level processes to mechanisms that operate on the capillary level, a shift that has brought into sharp focus questions regarding the fine control of blood distribution to active neurons. As these investigations have drilled down into finer reaches of the microvasculature, they have revealed an arteriole-proximate subregion of CNS capillary networks that serves a regulatory function in directing blood flow into and within downstream capillaries. They have also illuminated differences in researchers' perspectives on the vascular structures and identity of mural cells in this region that impart the vasomodulatory effects that control blood distribution. In this review, we highlight the regulatory role of a variably named region of the microvasculature, referred to here as the post-arteriole transition zone, in channeling blood flow within CNS capillary networks, and underscore the contribution of dynamically contractile perivascular mural cell - generally, but not universally, recognized as pericytes - to this function.
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Affiliation(s)
- Amreen Mughal
- Department of Pharmacology, University of Vermont, Burlington, VT, USA
| | - Mark T. Nelson
- Department of Pharmacology, University of Vermont, Burlington, VT, USA
- Division of Cardiovascular Sciences, University of Manchester, Manchester, UK
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16
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Cai C, Zambach SA, Grubb S, Tao L, He C, Lind BL, Thomsen KJ, Zhang X, Hald BO, Nielsen RM, Kim K, Devor A, Lønstrup M, Lauritzen MJ. Impaired dynamics of precapillary sphincters and pericytes at first-order capillaries predict reduced neurovascular function in the aging mouse brain. Nat Aging 2023; 3:173-184. [PMID: 37118115 DOI: 10.1038/s43587-022-00354-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 12/20/2022] [Indexed: 04/30/2023]
Abstract
The microvascular inflow tract, comprising the penetrating arterioles, precapillary sphincters and first-order capillaries, is the bottleneck for brain blood flow and energy supply. Exactly how aging alters the structure and function of the microvascular inflow tract remains unclear. By in vivo four-dimensional two-photon imaging, we reveal an age-dependent decrease in vaso-responsivity accompanied by a decrease in vessel density close to the arterioles and loss of vascular mural cell processes, although the number of mural cell somas and their alpha smooth muscle actin density were preserved. The age-related reduction in vascular reactivity was mostly pronounced at precapillary sphincters, highlighting their crucial role in capillary blood flow regulation. Mathematical modeling revealed impaired pressure and flow control in aged mice during vasoconstriction. Interventions that preserve dynamics of cerebral blood vessels may ameliorate age-related decreases in blood flow and prevent brain frailty.
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Affiliation(s)
- Changsi Cai
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark.
| | - Stefan Andreas Zambach
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Søren Grubb
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Lechan Tao
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
- School of Biomedical Engineering, Shanghai Jiao-Tong University, Shanghai, China
| | - Chen He
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Barbara Lykke Lind
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Kirsten Joan Thomsen
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Xiao Zhang
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Bjørn Olav Hald
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Reena Murmu Nielsen
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Kayeon Kim
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Anna Devor
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Harvard Medical School, Massachusetts General Hospital, Charlestown, MA, USA
| | - Micael Lønstrup
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Martin Johannes Lauritzen
- Department of Neuroscience, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark.
- Department of Clinical Neurophysiology, Rigshospitalet, Copenhagen, Denmark.
- Center for Healthy Aging, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark.
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17
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Averyanova IV, Vdovenko SI. [Capillary blood flow morphofunctional readjustments in northerners of different ages.]. Adv Gerontol 2023; 36:29-35. [PMID: 37192351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Morphofunctional characteristics of capillary blood flow can be considered one of the most sensitive markers of ontogenetic desadaptive changes both within a local area of the capillary network and in the entire cardiovascular system. The study involved two hundred seventy-seven male northerners aged 18-66 to identify the age dynamics of the capillary bed morphofunctional characteristics. Subjects exhibited a reduction in diameters of arterial and transitional sections of the microcapillary bed testifying to a significant age dynamics from young men to the elderly. The remodeling coefficient increasingly came up in workable and elderly men, which indicated the risk of reducing in effectiveness of substances diffusion. We could see the average capillary length increase in this age vector and considered that as a compensatory growth of the contact surface of the vessel aimed at maintaining the necessary level of transcapillary exchange. We clearly observed microcirculatory changes with subjective age and considered them to be adaptive changes of microangioarchitectonics which may indicate the formation of a pattern characteristic of northerners' ontogenetic readjustments.
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Affiliation(s)
- I V Averyanova
- Scientific Research Center «Arktika» Far Eastern Branch of RAS, 24 pr. Karla Marksa, 685000 Magadan, Russian Federation, e-mail:
| | - S I Vdovenko
- Scientific Research Center «Arktika» Far Eastern Branch of RAS, 24 pr. Karla Marksa, 685000 Magadan, Russian Federation, e-mail:
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18
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Takakura N. [Vascular biology and hemophilia]. Rinsho Ketsueki 2023; 64:661-664. [PMID: 37544727 DOI: 10.11406/rinketsu.64.661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
By carrying a systemic circulation, hematopoietic and vascular systems coordinately govern the functional organ connections in the body. Blood vessels play an important role in the development, regeneration, and maintenance of organs by acting as conduits for environmental factors in the blood to tissues and secreting organ-specific cytokines as angiocrine signals. Recently, it has become clear that vascular endothelial cells, which are the main constituent cells of the blood vessels and play a role in homeostasis, are diverse. It has also been established that the cells of stem cell fraction exist in endothelial cells. The vascular endothelial cells in various organs are functionally different. For example, it has been discovered that sinusoidal blood vessels in the liver produce coagulation factor VIII as an organ-specific vascular function. Determining how such tissue-/organ-specific function of the endothelial cells is induced is a topic of interest in the vascular field of study.
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Affiliation(s)
- Nobuyuki Takakura
- Department of Signal Transduction, Research Institute for Microbial Diseases, Osaka University
- IFReC, Osaka University
- Institute for Open and Transdisciplinary Research Initiatives, OTRI, Osaka University
- CiDER, Osaka University
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19
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Kovtanyuk A, Turova V, Sidorenko I, Chebotarev A, Lampe R. Modeling of the cerebral blood circulation in a capillary network accounting for the influence of the endothelial surface layer. Comput Methods Programs Biomed 2022; 224:107008. [PMID: 35901640 DOI: 10.1016/j.cmpb.2022.107008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 06/22/2022] [Accepted: 07/05/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND AND OBJECTIVE The paper describes a mathematical model of blood flow in capillaries with accounting for the endothelial surface layer (ESL). METHOD The influence of ESL is modeled by a boundary layer with zero flow velocity. Finite element modeling and an analytical approach based on the homogenization of the core region of blood flow occupied by erythrocytes are developed to describe the resistance of a capillary. The reliability of the results obtained is verified for different values of the discharge hematocrit and vessel diameter using known in vivo data. RESULTS The proposed approach is applied to the numerical simulation of blood circulation in a capillary network of the germinal matrix of infants born at 25 gestational weeks. The influence of the hematocrit level and effective thickness of ESL on the resistance of the capillary network of the germinal matrix of preterm infants is studied. It was found that a decrease in the effective thickness of ESL in the capillary network (and/or a decrease in the hematocrit) leads to reducing the resistance of the capillary network. CONCLUSION A decrease in the effective thickness of ESL in the capillary network leads to an increase in the pressure drop in arterioles, which may be considered as an additional risk factor for hemorrhages in fragile blood vessels within the germinal matrix.
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Affiliation(s)
- Andrey Kovtanyuk
- Klinikum rechts der Isar, Technische Universität München, Ismaningerstr. 22, München, 81675, Germany.
| | - Varvara Turova
- Klinikum rechts der Isar, Technische Universität München, Ismaningerstr. 22, München, 81675, Germany.
| | - Irina Sidorenko
- Fakultät für Mathematik, Technische Universität München, Boltzmannstr. 3, Garching bei München, 85747, Germany.
| | - Alexander Chebotarev
- Far Eastern Federal University, Far Eastern Center for Research and Education in Mathematics, Ajax Bay 10, Russky Island, Vladivostok, 690922, Russia.
| | - Renée Lampe
- Klinikum rechts der Isar, Technische Universität München, Ismaningerstr. 22, München, 81675, Germany.
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20
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Ebrahimi S, Bagchi P. Application of machine learning in predicting blood flow and red cell distribution in capillary vessel networks. J R Soc Interface 2022; 19:20220306. [PMID: 35946164 PMCID: PMC9363992 DOI: 10.1098/rsif.2022.0306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 07/21/2022] [Indexed: 11/12/2022] Open
Abstract
Capillary blood vessels in the body partake in the exchange of gas and nutrients with tissues. They are interconnected via multiple vascular junctions forming the microvascular network. Distributions of blood flow and red cells (RBCs) in such networks are spatially uneven and vary in time. Since they dictate the pathophysiology of tissues, their knowledge is important. Theoretical models used to obtain flow and RBC distribution in large networks have limitations as they treat each vessel as a one-dimensional segment and do not explicitly consider cell-cell and cell-vessel interactions. High-fidelity computational models that accurately model each individual RBC are computationally too expensive to predict haemodynamics in large vascular networks and over a long time. Here we investigate the applicability of machine learning (ML) techniques to predict blood flow and RBC distributions in physiologically realistic vascular networks. We acquire data from high-fidelity simulations of deformable RBC suspension flowing in the networks. With the flow and haematocrit specified at an inlet of vasculature, the ML models predict the time-averaged flow rate and RBC distributions in the entire network, time-dependent flow rate and haematocrit in each vessel and vascular bifurcation in isolation over a long time, and finally, simultaneous spatially and temporally evolving quantities through the vessel hierarchy in the networks.
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Affiliation(s)
- Saman Ebrahimi
- Mechanical and Aerospace Engineering Department, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Prosenjit Bagchi
- Mechanical and Aerospace Engineering Department, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
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21
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Puttaswamy SV, Bhattacharya G, Raj S, Bhalla N, Lee C, McLaughlin J. Effect of Functional Electrical Stimulation on Capillary Blood Flow to Muscle. Annu Int Conf IEEE Eng Med Biol Soc 2022; 2022:1573-1576. [PMID: 36086637 DOI: 10.1109/embc48229.2022.9871395] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Functional electrical stimulation (FES) modifies red blood cells (RBCs) flux in blood capillaries of muscle. In this work, we aim to investigate changes in the RBC flux in small and large capillaries due to FES using zinc oxide nanowires (ZnO NWs) based electrode at different stimulation parameters. The RBC flux was significantly increased immediately after stimulation, which was evident from decreasing light intensity measured in the region of interest. Clinical Relevance- FES has numerous forms and functions. The benefit of FES is the increased blood flow to a muscle which is contracted abnormally. This work explores the use of FES to increase the blood flow and RBC flux in blood capillaries of stimulated muscle as FES generate muscle contraction and absorption.
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22
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Hyakutake T, Abe H, Miyoshi Y, Yasui M, Suzuki R, Tsurumaki S, Tsutsumi Y. In vitro study on the partitioning of red blood cells using a microchannel network. Microvasc Res 2021; 140:104281. [PMID: 34871649 DOI: 10.1016/j.mvr.2021.104281] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 11/11/2021] [Accepted: 11/13/2021] [Indexed: 11/18/2022]
Abstract
To investigate the partitioning properties of red blood cells (RBCs) in the bifurcating capillary vessels, an in vitro experiment was performed to perfuse human RBC suspensions into the microfluidic channels with a width of <10 μm. Two types of microchannel geometries were established. One is a single model comprising one parent and two daughter channels with different widths, and the other is a network model that had a symmetric geometry with four consecutive divergences and convergences. In addition to the fractional RBC flux at each bifurcation, changes in hematocrit levels and flow velocity before and after the bifurcation were investigated. In the single model, non-uniform partitioning of RBCs was observed, and this result was in good agreement with that of the empirical model. Furthermore, in the network model, the RBC distribution in the cross-section before the bifurcation significantly affected RBC partitioning in the two channels after the bifurcation. Hence, there was a large RBC heterogeneity in the capillary network. The hematocrit levels between the channels differed for more than one order of magnitude. Therefore, the findings of the current research could facilitate a better understanding of RBC partitioning properties in the microcirculatory system.
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Affiliation(s)
- Toru Hyakutake
- Faculty of Engineering, Yokohama National University, 79-5, Hodogaya, Yokohama 240-8501, Japan.
| | - Hiroki Abe
- Graduate School of Engineering, Yokohama National University, 79-5, Hodogaya, Yokohama 240-8501, Japan
| | - Yohei Miyoshi
- Graduate School of Engineering, Yokohama National University, 79-5, Hodogaya, Yokohama 240-8501, Japan
| | - Manabu Yasui
- Kanagawa Institute of Industrial Science and Technology, 705-1, Shimoimaizumi, Ebina 243-0435, Japan
| | - Rina Suzuki
- Graduate School of Engineering, Yokohama National University, 79-5, Hodogaya, Yokohama 240-8501, Japan
| | - Shunto Tsurumaki
- Graduate School of Engineering, Yokohama National University, 79-5, Hodogaya, Yokohama 240-8501, Japan
| | - Yuya Tsutsumi
- Graduate School of Engineering, Yokohama National University, 79-5, Hodogaya, Yokohama 240-8501, Japan
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23
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Massamba N, Mackin AG, Chun LY, Rodriguez S, Dimitroyannis RC, Bodaghi B, Hariprasad SM, Skondra D. Evaluation of flow of chorioretinal capillaries in healthy black and white subjects using optical coherence tomography angiography. Sci Rep 2021; 11:21886. [PMID: 34750481 PMCID: PMC8575995 DOI: 10.1038/s41598-021-01380-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 10/11/2021] [Indexed: 12/18/2022] Open
Abstract
This study compared macular capillary parameters between healthy black and white subjects using optical coherence tomography angiography (OCTA). We measured vessel density (VD) of superficial (SCP), intermediate (ICP), and deep (DCP) capillary plexuses and choriocapillaris blood flow area (BFA) of the fovea, parafovea and total 3 mm-diameter circular area centered on the fovea, as well as the foveal avascular zone (FAZ) parameters, controlling for axial length. Black subjects had lower foveal and parafoveal VD in the SCP (p = 0.043 and p = 0.014) and the ICP (p = 0.014 and p = 0.002). In the DCP, black subjects had a trend toward lower foveal and parafoveal VD. Black subjects had decreased choriocapillaris BFA in the total 3 mm area (p = 0.011) and the parafovea (p = 0.033), larger FAZ area (p = 0.006) and perimeter (p = 0.014), and a higher capillary density in a 300 μm wide region around the FAZ (FD-300) (p = 0.001). There was no significant difference in FAZ acircularity index. To our knowledge, this is the first report analyzing the three distinct retinal capillary plexuses and identifying differing baseline VD, choriocapillaris and FAZ parameters in healthy young black compared to white subjects. Larger studies are needed to validate these findings and better understand racial differences in vulnerability to ocular diseases.
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Affiliation(s)
- Nathalie Massamba
- Department of Ophthalmology and Visual Science, The University of Chicago, 5841 S. Maryland Avenue, S426m MC2114, Chicago, IL, 60637, USA
- Department of Ophthalmology, Handicap, and Vision, Pitie Salpetriere Hospital, Sorbonne University, Paris, France
- J. Terry Ernest Ocular Imaging Center, The University of Chicago, Chicago, IL, USA
| | - Anna G Mackin
- Department of Ophthalmology and Visual Science, The University of Chicago, 5841 S. Maryland Avenue, S426m MC2114, Chicago, IL, 60637, USA
| | - Lindsay Y Chun
- Department of Ophthalmology and Visual Science, The University of Chicago, 5841 S. Maryland Avenue, S426m MC2114, Chicago, IL, 60637, USA
| | - Sarah Rodriguez
- Department of Ophthalmology and Visual Science, The University of Chicago, 5841 S. Maryland Avenue, S426m MC2114, Chicago, IL, 60637, USA
| | - Rose C Dimitroyannis
- Department of Ophthalmology and Visual Science, The University of Chicago, 5841 S. Maryland Avenue, S426m MC2114, Chicago, IL, 60637, USA
| | - Bahram Bodaghi
- Department of Ophthalmology, Handicap, and Vision, Pitie Salpetriere Hospital, Sorbonne University, Paris, France
| | - Seenu M Hariprasad
- Department of Ophthalmology and Visual Science, The University of Chicago, 5841 S. Maryland Avenue, S426m MC2114, Chicago, IL, 60637, USA
| | - Dimitra Skondra
- Department of Ophthalmology and Visual Science, The University of Chicago, 5841 S. Maryland Avenue, S426m MC2114, Chicago, IL, 60637, USA.
- J. Terry Ernest Ocular Imaging Center, The University of Chicago, Chicago, IL, USA.
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24
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Hennigs JK, Matuszcak C, Trepel M, Körbelin J. Vascular Endothelial Cells: Heterogeneity and Targeting Approaches. Cells 2021; 10:2712. [PMID: 34685692 PMCID: PMC8534745 DOI: 10.3390/cells10102712] [Citation(s) in RCA: 65] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 10/01/2021] [Accepted: 10/05/2021] [Indexed: 01/18/2023] Open
Abstract
Forming the inner layer of the vascular system, endothelial cells (ECs) facilitate a multitude of crucial physiological processes throughout the body. Vascular ECs enable the vessel wall passage of nutrients and diffusion of oxygen from the blood into adjacent cellular structures. ECs regulate vascular tone and blood coagulation as well as adhesion and transmigration of circulating cells. The multitude of EC functions is reflected by tremendous cellular diversity. Vascular ECs can form extremely tight barriers, thereby restricting the passage of xenobiotics or immune cell invasion, whereas, in other organ systems, the endothelial layer is fenestrated (e.g., glomeruli in the kidney), or discontinuous (e.g., liver sinusoids) and less dense to allow for rapid molecular exchange. ECs not only differ between organs or vascular systems, they also change along the vascular tree and specialized subpopulations of ECs can be found within the capillaries of a single organ. Molecular tools that enable selective vascular targeting are helpful to experimentally dissect the role of distinct EC populations, to improve molecular imaging and pave the way for novel treatment options for vascular diseases. This review provides an overview of endothelial diversity and highlights the most successful methods for selective targeting of distinct EC subpopulations.
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Affiliation(s)
- Jan K. Hennigs
- ENDomics Lab, Department of Oncology, Hematology and Bone Marrow Transplantation with Section Pneumology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany;
| | - Christiane Matuszcak
- ENDomics Lab, Department of Oncology, Hematology and Bone Marrow Transplantation with Section Pneumology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany;
| | - Martin Trepel
- Department of Hematology and Medical Oncology, University Medical Center Augsburg, 86156 Augsburg, Germany;
| | - Jakob Körbelin
- ENDomics Lab, Department of Oncology, Hematology and Bone Marrow Transplantation with Section Pneumology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany;
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Gliemann L, Rytter N, Jørgensen TS, Piil P, Carter H, Nyberg M, Grassi M, Daumer M, Hellsten Y. The Impact of Lower Limb Immobilization and Rehabilitation on Angiogenic Proteins and Capillarization in Skeletal Muscle. Med Sci Sports Exerc 2021; 53:1797-1806. [PMID: 33787530 DOI: 10.1249/mss.0000000000002665] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE Skeletal muscle vascularization is important for tissue regeneration after injury and immobilization. We examined whether complete immobilization influences capillarization and oxygen delivery to the muscle and assessed the efficacy of rehabilitation by aerobic exercise training. METHODS Young healthy males had one leg immobilized for 14 d and subsequently completed 4 wk of intense aerobic exercise training. Biopsies were obtained from musculus vastus lateralis, and arteriovenous blood sampling for assessment of oxygen extraction and leg blood flow during exercise was done before and after immobilization and training. Muscle capillarization, muscle and platelet content of vascular endothelial growth factor (VEGF), and muscle thrombospondin-1 were determined. RESULTS Immobilization did not have a significant impact on capillary per fiber ratio or capillary density. The content of VEGF protein in muscle samples was reduced by 36% (P = 0.024), and VEGF to thrombospondin-1 ratio was 94% lower (P = 0.046). The subsequent 4-wk training period increased the muscle VEGF content and normalized the muscle VEGF to thrombospondin-1 ratio but did not influence capillarization. Platelet VEGF content followed the trend of muscle VEGF. At the functional level, oxygen extraction, blood flow, and oxygen delivery at rest and during submaximal exercise were not affected by immobilization or training. CONCLUSIONS The results demonstrate that just 2 wk of leg immobilization leads to a strongly reduced angiogenic potential as evidenced by reduced muscle and platelet VEGF content and a reduced muscle VEGF to thrombospondin-1 ratio. Moreover, a subsequent period of intensive aerobic exercise training fails to increase capillarization in the previously immobilized leg, possibly because of the angiostatic condition caused by immobilization.
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Affiliation(s)
- Lasse Gliemann
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, DENMARK
| | - Nicolai Rytter
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, DENMARK
| | - Tue Smith Jørgensen
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, DENMARK
| | - Peter Piil
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, DENMARK
| | - Howard Carter
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, DENMARK
| | - Michael Nyberg
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, DENMARK
| | - Marcello Grassi
- Technical University of Munich, Germany. Sylvia Lawry Centre for Multiple Sclerosis Research, Munich, GERMANY
| | - Martin Daumer
- Technical University of Munich, Germany. Sylvia Lawry Centre for Multiple Sclerosis Research, Munich, GERMANY
| | - Ylva Hellsten
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, DENMARK
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Anzabi M, Li B, Wang H, Kura S, Sakadžić S, Boas D, Østergaard L, Ayata C. Optical coherence tomography of arteriolar diameter and capillary perfusion during spreading depolarizations. J Cereb Blood Flow Metab 2021; 41:2256-2263. [PMID: 33593116 PMCID: PMC8393288 DOI: 10.1177/0271678x21994013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Revised: 12/21/2020] [Accepted: 01/08/2021] [Indexed: 11/17/2022]
Abstract
Spreading depolarization (SD) is associated with profound oligemia and reduced oxygen availability in the mouse cortex during the depolarization phase. Coincident pial arteriolar constriction has been implicated as the primary mechanism for the oligemia. However, where in the vascular bed the hemodynamic response starts has been unclear. To resolve the origin of the hemodynamic response, we used optical coherence tomography (OCT) to simultaneously monitor changes in the vascular tree from capillary bed to pial arteries in mice during two consecutive SDs 15 minutes apart. We found that capillary flow dropped several seconds before pial arteriolar constriction. Moreover, penetrating arterioles constricted before pial arteries suggesting upstream propagation of constriction. Smaller caliber distal pial arteries constricted stronger than larger caliber proximal arterioles, suggesting that the farther the constriction propagates, the weaker it gets. Altogether, our data indicate that the hemodynamic response to cortical SD originates in the capillary bed.
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Affiliation(s)
- Maryam Anzabi
- Neurovascular Research Unit, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, USA
- Center of Functionally Integrative Neuroscience (CFIN) and MINDLab, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Baoqiang Li
- Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences
| | - Hui Wang
- Shenzhen-Hong Kong Institute of Brain Science, Shenzhen Fundamental Research Institutions, Shenzhen, China
| | - Sreekanth Kura
- Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, USA
| | - Sava Sakadžić
- Shenzhen-Hong Kong Institute of Brain Science, Shenzhen Fundamental Research Institutions, Shenzhen, China
| | - David Boas
- Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, USA
| | - Leif Østergaard
- Center of Functionally Integrative Neuroscience (CFIN) and MINDLab, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Cenk Ayata
- Neurovascular Research Unit, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, USA
- Neurophotonics Center, Department of Biomedical Engineering, Boston University, Boston, USA
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Tsai CJ, Nagata T, Liu CY, Suganuma T, Kanda T, Miyazaki T, Liu K, Saitoh T, Nagase H, Lazarus M, Vogt KE, Yanagisawa M, Hayashi Y. Cerebral capillary blood flow upsurge during REM sleep is mediated by A2a receptors. Cell Rep 2021; 36:109558. [PMID: 34407410 DOI: 10.1016/j.celrep.2021.109558] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 06/05/2021] [Accepted: 07/28/2021] [Indexed: 11/16/2022] Open
Abstract
Sleep is generally viewed as a period of recovery, but how the supply of cerebral blood flow (CBF) changes across sleep/wake states has remained unclear. Here, we directly observe red blood cells (RBCs) within capillaries, where the actual substance exchange between the blood and neurons/glia occurs, by two-photon microscopy. Across multiple cortical areas, average capillary CBF is largely increased during rapid eye movement (REM) sleep, whereas it does not differ between periods of active wakefulness and non-REM sleep. Capillary RBC flow during REM sleep is further elevated following REM sleep deprivation, suggesting that capillary CBF reflects REM sleep pressure. At the molecular level, signaling via adenosine A2a receptors is crucial; in A2a-KO mice, capillary CBF upsurge during REM sleep is dampened, and effects of REM sleep pressure are abolished. These results provide evidence regarding the dynamics of capillary CBF across sleep/wake states and insights to the underlying mechanisms.
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Affiliation(s)
- Chia-Jung Tsai
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan; Japan Society for the Promotion of Science (JSPS) International Research Fellow, Tokyo 102-0083, Japan
| | - Takeshi Nagata
- PhD Program in Human Biology, School of Integrative and Global Majors, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
| | - Chih-Yao Liu
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
| | - Takaya Suganuma
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
| | - Takeshi Kanda
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
| | - Takehiro Miyazaki
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
| | - Kai Liu
- Center for Mathematical Sciences, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Tsuyoshi Saitoh
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
| | - Hiroshi Nagase
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
| | - Michael Lazarus
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan; PhD Program in Human Biology, School of Integrative and Global Majors, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
| | - Kaspar E Vogt
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan; PhD Program in Human Biology, School of Integrative and Global Majors, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
| | - Masashi Yanagisawa
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan; PhD Program in Human Biology, School of Integrative and Global Majors, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan; Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Life Science Center for Survival Dynamics (TARA), University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan; R&D Center for Frontiers of Mirai in Policy and Technology (F-MIRAI), University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
| | - Yu Hayashi
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan; PhD Program in Human Biology, School of Integrative and Global Majors, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan; Department of Human Health Sciences, Graduate School of Medicine, Kyoto University, 53 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 603-8363, Japan.
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Rungta RL, Zuend M, Aydin AK, Martineau É, Boido D, Weber B, Charpak S. Diversity of neurovascular coupling dynamics along vascular arbors in layer II/III somatosensory cortex. Commun Biol 2021; 4:855. [PMID: 34244604 PMCID: PMC8270975 DOI: 10.1038/s42003-021-02382-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 06/10/2021] [Indexed: 11/08/2022] Open
Abstract
The spatial-temporal sequence of cerebral blood flow (CBF), cerebral blood volume (CBV) and blood velocity changes triggered by neuronal activation is critical for understanding functional brain imaging. This sequence follows a stereotypic pattern of changes across different zones of the vasculature in the olfactory bulb, the first relay of olfaction. However, in the cerebral cortex, where most human brain mapping studies are performed, the timing of activity evoked vascular events remains controversial. Here we utilized a single whisker stimulation model to map out functional hyperemia along vascular arbours from layer II/III to the surface of primary somatosensory cortex, in anesthetized and awake Thy1-GCaMP6 mice. We demonstrate that sensory stimulation triggers an increase in blood velocity within the mid-capillary bed and a dilation of upstream large capillaries, and the penetrating and pial arterioles. We report that under physiological stimulation, response onset times are highly variable across compartments of different vascular arbours. Furthermore, generating transfer functions (TFs) between neuronal Ca2+ and vascular dynamics across different brain states demonstrates that anesthesia decelerates neurovascular coupling (NVC). This spatial-temporal pattern of vascular events demonstrates functional diversity not only between different brain regions but also at the level of different vascular arbours within supragranular layers of the cerebral cortex.
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Affiliation(s)
- Ravi L Rungta
- INSERM U1128, Laboratory of Neurophysiology and New Microscopy, Université Paris Descartes, Paris, France.
- Faculté de Médecine Dentaire, Université de Montréal, Montréal, QC, Canada.
- Centre Interdisciplinaire de Recherche sur le Cerveau et l'Apprentissage, Université de Montréal, Montréal, QC, Canada.
- Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, Montréal, QC, Canada.
| | - Marc Zuend
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Ali-Kemal Aydin
- INSERM U1128, Laboratory of Neurophysiology and New Microscopy, Université Paris Descartes, Paris, France
- INSERM, CNRS, Institut de la Vision, Sorbonne Université, Paris, France
| | - Éric Martineau
- Faculté de Médecine Dentaire, Université de Montréal, Montréal, QC, Canada
- Centre Interdisciplinaire de Recherche sur le Cerveau et l'Apprentissage, Université de Montréal, Montréal, QC, Canada
- Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, Montréal, QC, Canada
| | - Davide Boido
- INSERM U1128, Laboratory of Neurophysiology and New Microscopy, Université Paris Descartes, Paris, France
- NeuroSpin, Bat. 145, Commissariat à l'Energie Atomique ' Saclay Center, Gif-sur-Yvette, France
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Serge Charpak
- INSERM U1128, Laboratory of Neurophysiology and New Microscopy, Université Paris Descartes, Paris, France.
- INSERM, CNRS, Institut de la Vision, Sorbonne Université, Paris, France.
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Ji X, Ferreira T, Friedman B, Liu R, Liechty H, Bas E, Chandrashekar J, Kleinfeld D. Brain microvasculature has a common topology with local differences in geometry that match metabolic load. Neuron 2021; 109:1168-1187.e13. [PMID: 33657412 PMCID: PMC8525211 DOI: 10.1016/j.neuron.2021.02.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 12/09/2020] [Accepted: 02/03/2021] [Indexed: 01/03/2023]
Abstract
The microvasculature underlies the supply networks that support neuronal activity within heterogeneous brain regions. What are common versus heterogeneous aspects of the connectivity, density, and orientation of capillary networks? To address this, we imaged, reconstructed, and analyzed the microvasculature connectome in whole adult mice brains with sub-micrometer resolution. Graph analysis revealed common network topology across the brain that leads to a shared structural robustness against the rarefaction of vessels. Geometrical analysis, based on anatomically accurate reconstructions, uncovered a scaling law that links length density, i.e., the length of vessel per volume, with tissue-to-vessel distances. We then derive a formula that connects regional differences in metabolism to differences in length density and, further, predicts a common value of maximum tissue oxygen tension across the brain. Last, the orientation of capillaries is weakly anisotropic with the exception of a few strongly anisotropic regions; this variation can impact the interpretation of fMRI data.
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Affiliation(s)
- Xiang Ji
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Tiago Ferreira
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA 20147, USA
| | - Beth Friedman
- Department of Computer Science and Engineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Rui Liu
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Hannah Liechty
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Erhan Bas
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA 20147, USA
| | | | - David Kleinfeld
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA; Section of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA.
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Pandya M, Saxon M, Bozanich J, Tillberg C, Luan X, Diekwisch TG. The Glycoprotein/Cytokine Erythropoietin Promotes Rapid Alveolar Ridge Regeneration In Vivo by Promoting New Bone Extracellular Matrix Deposition in Conjunction with Coupled Angiogenesis/Osteogenesis. Int J Mol Sci 2021; 22:2788. [PMID: 33801825 PMCID: PMC8002021 DOI: 10.3390/ijms22062788] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 03/01/2021] [Accepted: 03/05/2021] [Indexed: 12/20/2022] Open
Abstract
The loss of bone following tooth extraction poses a significant clinical problem for maxillofacial esthetics, function, and future implant placement. In the present study, the efficacy of an erythropoietin-impregnated collagen scaffold as an alveolar ridge augmentation material versus a conventional collagen scaffold and a BioOss inorganic bovine bone xenograft was examined. The collagen/Erythropoietin (EPO) scaffold exhibited significantly more rapid and complete osseous regeneration of the alveolar defect when compared to bone xenograft and the collagen membrane alone. The new EPO induced extracellular matrix was rich in Collagen I, Collagen III, Fibronectin (Fn) and E-cadherin, and featured significantly increased levels of the osteogenic transcription factors Runt-related transcription factor 2 (Runx2) and Osterix (Osx). Histomorphometric evaluation revealed a significant two-fold increase in the number of capillaries between the EPO and the BioOss group. Moreover, there was a highly significant 3.5-fold higher level of vascular endothelial growth factor (VEGF) in the collagen/EPO-treated group compared to controls. The significant effect of EPO on VEGF, FN, and RUNX2 upregulation was confirmed in vitro, and VEGF pathway analysis using VEGF inhibitors confirmed that EPO modulated extracellular matrix protein expression through VEGF even in the absence of blood vessels. Together, these data demonstrate the effectiveness of an EPO-impregnated collagen scaffold for bone regeneration as it induces rapid matrix production and osseoinduction adjacent to new capillaries via VEGF.
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Affiliation(s)
- Mirali Pandya
- Center for Craniofacial Research and Diagnosis, Texas A&M College of Dentistry, 3302 Gaston Avenue, Dallas, TX 75246, USA; (M.P.); (C.T.); (X.L.)
- Department of Periodontics, Texas A&M College of Dentistry, 3302 Gaston Avenue, Dallas, TX 75246, USA; (M.S.); (J.B.)
| | - Matthew Saxon
- Department of Periodontics, Texas A&M College of Dentistry, 3302 Gaston Avenue, Dallas, TX 75246, USA; (M.S.); (J.B.)
| | - John Bozanich
- Department of Periodontics, Texas A&M College of Dentistry, 3302 Gaston Avenue, Dallas, TX 75246, USA; (M.S.); (J.B.)
| | - Connie Tillberg
- Center for Craniofacial Research and Diagnosis, Texas A&M College of Dentistry, 3302 Gaston Avenue, Dallas, TX 75246, USA; (M.P.); (C.T.); (X.L.)
| | - Xianghong Luan
- Center for Craniofacial Research and Diagnosis, Texas A&M College of Dentistry, 3302 Gaston Avenue, Dallas, TX 75246, USA; (M.P.); (C.T.); (X.L.)
- Department of Periodontics, Texas A&M College of Dentistry, 3302 Gaston Avenue, Dallas, TX 75246, USA; (M.S.); (J.B.)
| | - Thomas G.H. Diekwisch
- Center for Craniofacial Research and Diagnosis, Texas A&M College of Dentistry, 3302 Gaston Avenue, Dallas, TX 75246, USA; (M.P.); (C.T.); (X.L.)
- Department of Periodontics, Texas A&M College of Dentistry, 3302 Gaston Avenue, Dallas, TX 75246, USA; (M.S.); (J.B.)
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Rogers S, Lew VL. Up-down biphasic volume response of human red blood cells to PIEZO1 activation during capillary transits. PLoS Comput Biol 2021; 17:e1008706. [PMID: 33657092 PMCID: PMC7928492 DOI: 10.1371/journal.pcbi.1008706] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 01/14/2021] [Indexed: 02/07/2023] Open
Abstract
In this paper we apply a novel JAVA version of a model on the homeostasis of human red blood cells (RBCs) to investigate the changes RBCs experience during single capillary transits. In the companion paper we apply a model extension to investigate the changes in RBC homeostasis over the approximately 200000 capillary transits during the ~120 days lifespan of the cells. These are topics inaccessible to direct experimentation but rendered mature for a computational modelling approach by the large body of recent and early experimental results which robustly constrain the range of parameter values and model outcomes, offering a unique opportunity for an in depth study of the mechanisms involved. Capillary transit times vary between 0.5 and 1.5s during which the red blood cells squeeze and deform in the capillary stream transiently opening stress-gated PIEZO1 channels allowing ion gradient dissipation and creating minuscule quantal changes in RBC ion contents and volume. Widely accepted views, based on the effects of experimental shear stress on human RBCs, suggested that quantal changes generated during capillary transits add up over time to develop the documented changes in RBC density and composition during their long circulatory lifespan, the quantal hypothesis. Applying the new red cell model (RCM) we investigated here the changes in homeostatic variables that may be expected during single capillary transits resulting from transient PIEZO1 channel activation. The predicted quantal volume changes were infinitesimal in magnitude, biphasic in nature, and essentially irreversible within inter-transit periods. A sub-second transient PIEZO1 activation triggered a sharp swelling peak followed by a much slower recovery period towards lower-than-baseline volumes. The peak response was caused by net CaCl2 and fluid gain via PIEZO1 channels driven by the steep electrochemical inward Ca2+ gradient. The ensuing dehydration followed a complex time-course with sequential, but partially overlapping contributions by KCl loss via Ca2+-activated Gardos channels, restorative Ca2+ extrusion by the plasma membrane calcium pump, and chloride efflux by the Jacobs-Steward mechanism. The change in relative cell volume predicted for single capillary transits was around 10-5, an infinitesimal volume change incompatible with a functional role in capillary flow. The biphasic response predicted by the RCM appears to conform to the quantal hypothesis, but whether its cumulative effects could account for the documented changes in density during RBC senescence required an investigation of the effects of myriad transits over the full four months circulatory lifespan of the cells, the subject of the next paper.
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Affiliation(s)
- Simon Rogers
- School of Computing Science, University of Glasgow, United Kingdom
| | - Virgilio L. Lew
- Physiological Laboratory, Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Site, Cambridge, United Kingdom
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Golub AS, Nugent WH, Song BK. Spike of interstitial PO 2 produced by a twitch in rhythmically contracted muscle. Physiol Rep 2021; 9:e14699. [PMID: 33400848 PMCID: PMC7785101 DOI: 10.14814/phy2.14699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 11/27/2020] [Accepted: 12/05/2020] [Indexed: 11/29/2022] Open
Abstract
Oxygen (O2 ) exchange between capillaries and muscle cells in exercising muscles is of great interest for physiology and kinesiology. However, methodical limitations prevent O2 measurements on the millisecond scale. To bypass the constraints of quasi-continuous recording, progressive measurements of O2 partial pressure (PO2 ) in rhythmically contracting skeletal muscle were compiled to describe the O2 kinetics surrounding and including a single muscle contraction. Phosphorescence quenching microscopy measured PO2 in the interstitium of the rat spinotrapezius muscle. Measurements were triggered by contraction-inducing electrical pulses. For the first 60 seconds, measurement preceeded stimulation. After 60, measurement followed with a progressive 20 ms increment. Thus, the first 60 measurements describe the overall PO2 response to electrical stimulation initiated after a 10 second rest period, while 61-100 (stroboscopic mode) were compiled into a single 800 ms profile of the PO2 transient surrounding muscle contraction. Thirty seconds of stimulated contractions decreased interstitial PO2 from a baseline of 71 ± 1.4 mmHg to an "active" steady-state of 43 ± 1.5 mmHg. The stroboscopic mode compilation revealed an unexpected post-contractile rise in PO2 as a 205 ms spike with a maximum amplitude of 58 ± 3.8 mmHg at 68 ms, which restored 58% of the PO2 drop from baseline. Interpretation of this phenomenon is based on classical experiments by G.V. Anrep (1935), who discovered the rapid thrust of blood flow associated with muscle contraction. In addition to the metabolic implications during exercise, the physiological impact of these PO2 spikes may grow with an increased rate of rhythmical contractions in muscle or heart. NEW&NOTEWORTHY: The principal finding is a spike of interstitial PO2 , produced by a twitch in a rhythmically contracting muscle. A possible mechanism is flushing capillaries with arterial blood by mechanical forces. A technical novelty is the PO2 measurement with a "stroboscopic mode" and progressively increasing delay between stimulator pulse and PO2 measuring. That permitted a 20 ms time resolution for a 205 ms spike duration, using an excitation flash rate one per second.
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Farfán-Albarracín JD, Ramírez-Sierra CL, Espitia Segura OM, Pérez SH, Téllez Prada HA, Rueda Rodríguez MC, Lemus Espitia I, Bedoya AM. Diagnostic yield of capillary compared to venous glucose in the diagnosis of hypoglycorrhachia in children: A prospective, observational study. Brain Dev 2021; 43:63-68. [PMID: 32741582 DOI: 10.1016/j.braindev.2020.07.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 07/16/2020] [Accepted: 07/21/2020] [Indexed: 11/19/2022]
Abstract
INTRODUCTION The ratio of cerebrospinal fluid (CSF) glucose and blood glucose is of major relevance, conducting to the diagnosis of hypoglycorrhachia, which is a sign of neuroinfection, as well as a number of neurological diseases of genetic or neoplastic etiology. Glucose in capillary sample (glucometry) is a low cost, readily available technique, as compared to venous glucose. This study aims to compare glucometry to venous glucose in the diagnosis of hypoglycorrhachia in pediatric population. METHODS Prospective cross-sectional study based on data obtained from lumbar punctures in the period from February 2017 to January 2019 in a specialized pediatric institution in Colombia. RESULTS 97 patients were analyzed, aged 1 month to 17 years old, mean 7.67 years, 52 (53.61%) were female. 26 (26.8%) were diagnosed with hypoglycorrhachia. Pearson correlation coefficient for absolute venous and capillary glucose was 0.54, and 0.55 for the ratios of CSF glucose/venous glucose and CSF glucose/glucometry, which support a linear correlation between the variables in both, absolute values and ratios. Intraclass correlation coefficient was calculated for both, the venous glucose and glucometry ratios, which was 0.52, revealing a moderate agreement among the tests. Sensitivity and specificity of CSF glucose/glucometry, as compared to gold standard are 73.1% and 60.6% respectively; whereas predictive positive value (PPV) and negative predictive value (NPV), were 40.4% and 86.0%. CONCLUSION Glucometry cannot replace the glucose in venous sample in the diagnosis of hypoglycorrhachia in children.
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Affiliation(s)
| | | | | | - Sofy Helena Pérez
- Child Neurology Department, HOMI Fundación Hospital Pediátrico la Misericordia, Colombia; Child Neurology Unit, Pediatrics Department, Faculty of Medicine, National University of Colombia, Colombia
| | - Hugo Andrés Téllez Prada
- Child Neurology Department, HOMI Fundación Hospital Pediátrico la Misericordia, Colombia; Child Neurology Unit, Pediatrics Department, Faculty of Medicine, National University of Colombia, Colombia
| | - María Camila Rueda Rodríguez
- Child Neurology Department, HOMI Fundación Hospital Pediátrico la Misericordia, Colombia; Child Neurology Unit, Pediatrics Department, Faculty of Medicine, National University of Colombia, Colombia
| | - Ingrid Lemus Espitia
- Child Neurology Department, HOMI Fundación Hospital Pediátrico la Misericordia, Colombia; Child Neurology Unit, Pediatrics Department, Faculty of Medicine, National University of Colombia, Colombia
| | - Ana Maritza Bedoya
- Child Neurology Department, HOMI Fundación Hospital Pediátrico la Misericordia, Colombia; Child Neurology Unit, Pediatrics Department, Faculty of Medicine, National University of Colombia, Colombia
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Sekine H, Okano T. Capillary Networks for Bio-Artificial Three-Dimensional Tissues Fabricated Using Cell Sheet Based Tissue Engineering. Int J Mol Sci 2020; 22:ijms22010092. [PMID: 33374875 PMCID: PMC7795136 DOI: 10.3390/ijms22010092] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 12/17/2020] [Accepted: 12/18/2020] [Indexed: 12/31/2022] Open
Abstract
One of the most important challenges facing researchers in the field of regenerative medicine is to develop methods to introduce vascular networks into bioengineered tissues. Although cell scaffolds that slowly release angiogenic factors can promote post-transplantation angiogenesis, they cannot be used to construct thick tissues because of the time required for sufficient vascular network formation. Recently, the co-culture of graft tissue with vascular cells before transplantation has attracted attention as a way of promoting capillary angiogenesis. Although the co-cultured vascular cells can directly contribute to blood vessel formation within the tissue, a key objective that needs to be met is the construction of a continuous circulatory structure. Previously described strategies to reconstruct blood vessels include the culture of endothelial cells in a scaffold that contains microchannels or within the original vascular framework after decellularization of an entire organ. The technique, as developed by authors, involves the progressive stacking of three-layered cell sheets onto a vascular bed to induce the formation of a capillary network within the cell sheets. This approach enables the construction of thick, functional tissue of high cell density that can be transplanted by anastomosing its artery and vein (provided by the vascular bed) with host blood vessels.
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Affiliation(s)
- Hidekazu Sekine
- Institute of Advanced Biomedical Engineering and Science, Tokyo Women’s Medical University, Tokyo 162-8666, Japan
- Correspondence: ; Tel.: +81-3-3353-8111
| | - Teruo Okano
- Center for Advanced Medical and Life Science, Tokyo Women’s Medical University, Tokyo 162-8666, Japan;
- Cell Sheet Tissue Engineering Center (CSTEC), Department of Pharmaceutics & Pharmaceutical Chemistry, School of Medicine and College of Pharmacy, University of Utah, Salt Lake City, UT 84112, USA
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Akram J, Akbar NS, Tripathi D. Blood-based graphene oxide nanofluid flow through capillary in the presence of electromagnetic fields: A Sutterby fluid model. Microvasc Res 2020; 132:104062. [PMID: 32828761 DOI: 10.1016/j.mvr.2020.104062] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 08/14/2020] [Accepted: 08/18/2020] [Indexed: 11/17/2022]
Abstract
Pumping devices with the electrokinetics phenomena are important in many microscale transport phenomena in physiology. This study presents a theoretical and numerical investigation on the peristaltic pumping of non-Newtonian Sutterby nanofluid through capillary in presence of electromagnetohydrodynamics. Here blood (Sutterby fluid) is taken as a base fluid and nanofluid is prepared by the suspension of graphene oxide nanoparticle in blood. Graphene oxide is extremely useful in the medical domain for drug delivery and cancer treatment. The modified Buongiorno model for nanofluids and Poisson-Boltzmann ionic distribution is adopted for the formulation of the present problem. Constitutive flow equations are linearized by the implementation of approximations low Reynolds number, large wavelength, and the Debye-Hückel linearization. The numerical solution of reduced coupled and nonlinear set of equations is computed through Mathematica and graphical illustration is presented. Further, the impacts of buoyancy forces, thermal radiation, and mixed convection are also studied. It is revealed in this investigation that the inclusion of a large number of nanoparticles alters the flow characteristics significantly and boosts the heat transfer mechanism. Moreover, the pumping power of the peristaltic pump can be enhanced by the reduction in the width of the electric double layer which can be done by altering the electrolyte concentration.
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Affiliation(s)
- Javaria Akram
- School of Natural Sciences (SNS), National University of Sciences and Technology (NUST), Islamabad 44000, Pakistan.
| | - Noreen Sher Akbar
- DBS&H, CEME, National University of Sciences and Technology, Islamabad, Pakistan
| | - Dharmendra Tripathi
- Department of Mathematics, National Institute of Technology Uttarakhand, Srinagar -246174, India
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Cavedon V, Milanese C, Marchi A, Zancanaro C. Different amount of training affects body composition and performance in High-Intensity Functional Training participants. PLoS One 2020; 15:e0237887. [PMID: 32817652 PMCID: PMC7440620 DOI: 10.1371/journal.pone.0237887] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 08/04/2020] [Indexed: 01/10/2023] Open
Abstract
The effects of High-Intensity Functional Training (HIFT) on body composition and the relationship of the latter with performance are not well defined. In this work we investigated, by means of Dual-energy X-ray Absorptiometry, the relative proportions of fat-, lean soft tissue-, and mineral mass in CrossFit® (CF, a popular mode of HIFT) participants (n = 24; age, 28.2 ± 3.39 y; BMI, 25.3 ± 2.04 kg/m2) with at least 1 year of CF training experience and weekly amount of training > 10 h/w (n = 13; Higher Training, HT) or < 10 h/w (n = 11; Lower Training, LT) as well as age- matched and BMI-matched physically active controls (CHT, CLT). Performance was assessed in the “Fran” workout. Data were analyzed by one-way or repeated measures ANOVA where needed. Association between variables was assessed with the Pearson’s correlation coefficient r. Partial correlation was used where needed. Results showed that HT performed better than LT in the “Fran” (P < 0.001) and they had higher whole-body bone mineral density (P = 0.026) and higher lean soft mass (P = 0.002), and borderline lower percent fat mass (P = 0.050). The main difference between CF participants (HT, LT) and their respective controls (CHT, CLT) was a lower adiposity in the former. In CF participants, performance positively correlated with appendicular lean soft tissue mass (P = 0.030). It can be concluded that, in CF participants, a higher amount of weekly training improves most notably lean body mass and increases performance in association with increased skeletal muscle mass. CF participation is especially effective in reducing fat mass vs. age- and BMI-matched physically active controls.
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Affiliation(s)
- Valentina Cavedon
- Laboratory of Anthropometry and Body Composition, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Chiara Milanese
- Laboratory of Anthropometry and Body Composition, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
- * E-mail:
| | - Alessandro Marchi
- Laboratory of Anthropometry and Body Composition, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Carlo Zancanaro
- Laboratory of Anthropometry and Body Composition, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
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Bedggood P, Metha A. Recovering the appearance of the capillary blood column from under-sampled flow data. Opt Lett 2020; 45:4320-4323. [PMID: 32735288 DOI: 10.1364/ol.398168] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 06/23/2020] [Indexed: 06/11/2023]
Abstract
The regular spacing of cells in capillary flow results in spurious cell trajectories if the sampling rate is too low. This makes it difficult to identify cells, even if the velocity is known. Here, we demonstrate a software method to overcome this problem and validate it using high frame rate data with known velocity, which is downsampled to produce aliasing. The method assumes high spatial sampling, constant velocity over short epochs, and an incompressible blood column. Data in successive frames are shifted along the capillary tube axis according to the flow velocity, faithfully rendering cells and plasma. The velocity estimate, required as input to this procedure, can be obtained from either a) the blind optimization of a simple heuristic, or b) a recently proposed velocimetry algorithm, which appears to extend the aliasing limit.
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Chen Z, Zhou Q, Robin J, Razansky D. Widefield fluorescence localization microscopy for transcranial imaging of cortical perfusion with capillary resolution. Opt Lett 2020; 45:3470-3473. [PMID: 32630874 DOI: 10.1364/ol.396123] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 05/18/2020] [Indexed: 06/11/2023]
Abstract
Imaging of cerebral vasculature is impeded with the existing fluorescence microscopy methods due to intense light scattering in living tissues and the need for highly invasive craniotomy procedures to resolve structures on a capillary scale. We propose a widefield fluorescence localization microscopy technique for high-resolution transcranial imaging and quantitative assessment of cortical perfusion in mice. The method is based on tracking single fluorescent microparticles sparsely distributed in the blood stream using a simple CMOS camera and a continuous-wave laser source. We demonstrate quantitative transcranial in vivo mapping of the blood flow velocity and direction at capillary level resolution (5 µm) across the entire cortex. The new technique opens a new high-resolution transcranial window into the brain function in health and disease.
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Dybala MP, Kuznetsov A, Motobu M, Hendren-Santiago BK, Philipson LH, Chervonsky AV, Hara M. Integrated Pancreatic Blood Flow: Bidirectional Microcirculation Between Endocrine and Exocrine Pancreas. Diabetes 2020; 69:1439-1450. [PMID: 32198213 PMCID: PMC7306124 DOI: 10.2337/db19-1034] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 03/09/2020] [Indexed: 02/06/2023]
Abstract
The pancreatic islet is a highly vascularized endocrine micro-organ. The unique architecture of rodent islets, a so-called core-mantle arrangement seen in two-dimensional images, led researchers to seek functional implications for islet hormone secretion. Three models of islet blood flow were previously proposed, all based on the assumption that islet microcirculation occurs in an enclosed structure. Recent electrophysiological and molecular biological studies using isolated islets also presumed unidirectional flow. Using intravital analysis of the islet microcirculation in mice, we found that islet capillaries were continuously integrated to those in the exocrine pancreas, which made the islet circulation rather open, not self-contained. Similarly in human islets, the capillary structure was integrated with pancreatic microvasculature in its entirety. Thus, islet microcirculation has no relation to islet cytoarchitecture, which explains its well-known variability throughout species. Furthermore, tracking fluorescent-labeled red blood cells at the endocrine-exocrine interface revealed bidirectional blood flow, with similar variability in blood flow speed in both the intra- and extra-islet vasculature. To date, the endocrine and exocrine pancreas have been studied separately by different fields of investigators. We propose that the open circulation model physically links both endocrine and exocrine parts of the pancreas as a single organ through the integrated vascular network.
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Affiliation(s)
| | | | - Maki Motobu
- Department of Pathology, The University of Chicago, Chicago, IL
| | | | - Louis H Philipson
- Department of Medicine, The University of Chicago, Chicago, IL
- Department of Pediatrics, The University of Chicago, Chicago, IL
| | | | - Manami Hara
- Department of Medicine, The University of Chicago, Chicago, IL
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Zhou DB, Scott AW, Linz MO, Han IC, Castanos MV, Lynch G, Andrade Romo JS, Linderman RE, Carroll J, Rosen RB, Chui TY. Interocular asymmetry of foveal avascular zone morphology and parafoveal capillary density in sickle cell retinopathy. PLoS One 2020; 15:e0234151. [PMID: 32520956 PMCID: PMC7286490 DOI: 10.1371/journal.pone.0234151] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 05/19/2020] [Indexed: 02/01/2023] Open
Abstract
OBJECTIVES To examine interocular asymmetry of foveal avascular zone (FAZ) and parafoveal capillary density metrics in sickle cell retinopathy (SCR) using optical coherence tomography angiography (OCT-A). METHODS This cross-sectional, retrospective study evaluated SCR patients and unaffected controls who underwent 3x3mm macular OCT-A imaging using a spectral domain-OCT system. FAZ (area, perimeter, and acircularity index) and parafoveal capillary density metrics were computed for both eyes of each participant. In unaffected controls, interocular difference in FAZ and parafoveal capillary density metrics were evaluated using Bland-Altman plots. SCR patients with interocular difference outside the upper 97.5% and lower 2.5% limits of agreement from controls were defined as having interocular asymmetry. Area under receiver operating characteristic curve (AROC) was also performed to determine the ability of the absolute interocular difference to differentiate between subjects with SCR-including non-proliferative SCR (NP-SCR) and proliferative SCR (P-SCR)-and unaffected controls. RESULTS Thirty-one patients with SCR (21 NP-SCR and 10 P-SCR) and 14 race-matched and age-matched controls were included for analysis. Interocular asymmetry was seen for all FAZ and parafoveal capillary density metrics in NP-SCR and P-SCR subjects. SCR subjects showed greater disease severity in the left-eye for FAZ and parafoveal capillary density metrics. CONCLUSIONS NP-SCR and P-SCR patients demonstrated quantifiable interocular asymmetry in FAZ and parafoveal capillary density metrics compared to unaffected subjects, with left-eye predominance in disease severity.
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Affiliation(s)
- Davis B. Zhou
- Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai, New York, New York, United States of America
- Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Adrienne W. Scott
- Retina Division, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Marguerite O. Linz
- Retina Division, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Ian C. Han
- Retina Division, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, University of Iowa, Iowa City, Iowa, United States of America
| | - Maria V. Castanos
- Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai, New York, New York, United States of America
| | - Giselle Lynch
- Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai, New York, New York, United States of America
- Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Jorge S. Andrade Romo
- Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai, New York, New York, United States of America
| | - Rachel E. Linderman
- Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Joseph Carroll
- Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Richard B. Rosen
- Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai, New York, New York, United States of America
- Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Toco Y. Chui
- Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai, New York, New York, United States of America
- Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- * E-mail:
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41
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Herrera NA, Duchatsch F, Tardelli LP, Dionísio TJ, Shinohara AL, Santos CF, Amaral SL. MicroRNA-126 upregulation, induced by training, plays a role in controlling microcirculation in dexamethasone treated rats. Mol Cell Endocrinol 2020; 505:110732. [PMID: 31991160 DOI: 10.1016/j.mce.2020.110732] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 12/18/2019] [Accepted: 01/20/2020] [Indexed: 12/13/2022]
Abstract
Microcirculation maintenance is associated with microRNAs. Nevertheless, the role of microRNAs induced by training in preventing dexamethasone (DEX)-induced microvascular rarefaction remains unknown. The study aim was to investigate if training-induced microRNAs are able to improve microcirculation proteins and prevent DEX-induced microvascular rarefaction. Rats underwent training for 8 weeks and then were treated with DEX (50 μg/kg per day, s.c.) for 14 days. Arterial pressure was measured and tibialis anterior (TA) muscle was collected for analyses. DEX induced hypertension concomitantly with capillary density loss (CD, -23.9%) and decrease of VEGF (-43.0%), p-AKT/AKT (-39.6%) and Bcl-2 (-23.0%) and an increase in caspase-3-cleaved protein level (+34.0%) in TA muscle. Training upregulated microRNA-126 expression (+13.1%), prevented VEGF (+61.4%), p-AKT/AKT (+37.7%), Bcl-2 (+7.7%) decrease and caspase-3-cleaved (-23.1%) increase associated with CD (+54.7%) reduction and hypertension prevention. MiRNA-126 upregulation, induced by training, plays a role in controlling microcirculation, which may be a potential target against DEX-induced microvascular rarefaction.
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Affiliation(s)
- Naiara A Herrera
- Joint Graduate Program in Physiological Sciences, PIPGCF UFSCar/UNESP, Rodovia Washington Luiz, km 235 Monjolinho 676, CEP:13565-90, São Carlos, SP, Brazil
| | - Francine Duchatsch
- Joint Graduate Program in Physiological Sciences, PIPGCF UFSCar/UNESP, Rodovia Washington Luiz, km 235 Monjolinho 676, CEP:13565-90, São Carlos, SP, Brazil
| | - Lidieli P Tardelli
- Joint Graduate Program in Physiological Sciences, PIPGCF UFSCar/UNESP, Rodovia Washington Luiz, km 235 Monjolinho 676, CEP:13565-90, São Carlos, SP, Brazil
| | - Thiago J Dionísio
- Department of Biological Sciences, Bauru School of Dentistry, University of São Paulo, Alameda Octávio Pinheiro Brisolla 9-75, CEP 17012-901, Bauru, SP, Brazil
| | - Andre L Shinohara
- Department of Biological Sciences, Bauru School of Dentistry, University of São Paulo, Alameda Octávio Pinheiro Brisolla 9-75, CEP 17012-901, Bauru, SP, Brazil
| | - Carlos F Santos
- Department of Biological Sciences, Bauru School of Dentistry, University of São Paulo, Alameda Octávio Pinheiro Brisolla 9-75, CEP 17012-901, Bauru, SP, Brazil
| | - Sandra Lia Amaral
- Joint Graduate Program in Physiological Sciences, PIPGCF UFSCar/UNESP, Rodovia Washington Luiz, km 235 Monjolinho 676, CEP:13565-90, São Carlos, SP, Brazil; Department of Physical Education - São Paulo State University (UNESP), School of Sciences, Av. Eng. Luiz Edmundo Carrijo Coube, 14-01, Vargem Limpa, CEP 17033-360, Bauru, SP, Brazil.
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Chen MB, Yang AC, Yousef H, Lee D, Chen W, Schaum N, Lehallier B, Quake SR, Wyss-Coray T. Brain Endothelial Cells Are Exquisite Sensors of Age-Related Circulatory Cues. Cell Rep 2020; 30:4418-4432.e4. [PMID: 32234477 PMCID: PMC7292569 DOI: 10.1016/j.celrep.2020.03.012] [Citation(s) in RCA: 103] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 11/13/2019] [Accepted: 03/05/2020] [Indexed: 12/28/2022] Open
Abstract
Brain endothelial cells (BECs) are key constituents of the blood-brain barrier (BBB), protecting the brain from pathogens and restricting access of circulatory factors. Yet, because circulatory proteins have prominent age-related effects on adult neurogenesis, neuroinflammation, and cognitive function in mice, we wondered whether BECs receive and potentially relay signals between the blood and brain. Using single-cell RNA sequencing of hippocampal BECs, we discover that capillary BECs-compared with arterial and venous BECs-undergo the greatest transcriptional changes in normal aging, upregulating innate immunity and oxidative stress response pathways. Short-term infusions of aged plasma into young mice recapitulate key aspects of this aging transcriptome, and remarkably, infusions of young plasma into aged mice exert rejuvenation effects on the capillary transcriptome. Together, these findings suggest that the transcriptional age of BECs is exquisitely sensitive to age-related circulatory cues and pinpoint the BBB itself as a promising therapeutic target to treat brain disease.
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Affiliation(s)
- Michelle B Chen
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Andrew C Yang
- Department of Bioengineering, Stanford University, Stanford, CA, USA; Department of Neurology and Neurological Sciences, Stanford School of Medicine, Stanford, CA, USA; ChEM-H, Stanford University, Stanford, CA, USA
| | - Hanadie Yousef
- Department of Neurology and Neurological Sciences, Stanford School of Medicine, Stanford, CA, USA
| | - Davis Lee
- Department of Neurology and Neurological Sciences, Stanford School of Medicine, Stanford, CA, USA
| | - Winnie Chen
- Department of Neurology and Neurological Sciences, Stanford School of Medicine, Stanford, CA, USA
| | - Nicholas Schaum
- Department of Neurology and Neurological Sciences, Stanford School of Medicine, Stanford, CA, USA; Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Benoit Lehallier
- Department of Neurology and Neurological Sciences, Stanford School of Medicine, Stanford, CA, USA
| | - Stephen R Quake
- Department of Bioengineering, Stanford University, Stanford, CA, USA; Chan Zuckerberg Biohub, Stanford, CA 94305, USA.
| | - Tony Wyss-Coray
- Department of Neurology and Neurological Sciences, Stanford School of Medicine, Stanford, CA, USA; ChEM-H, Stanford University, Stanford, CA, USA; Department of Veterans Affairs, VA Palo Alto Health Care System, Palo Alto, CA 94304, USA; Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA, USA.
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Li B, Ohtomo R, Thunemann M, Adams SR, Yang J, Fu B, Yaseen MA, Ran C, Polimeni JR, Boas DA, Devor A, Lo EH, Arai K, Sakadžić S. Two-photon microscopic imaging of capillary red blood cell flux in mouse brain reveals vulnerability of cerebral white matter to hypoperfusion. J Cereb Blood Flow Metab 2020; 40:501-512. [PMID: 30829101 PMCID: PMC7026840 DOI: 10.1177/0271678x19831016] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 01/19/2019] [Accepted: 01/21/2019] [Indexed: 01/15/2023]
Abstract
Despite the importance of understanding the regulation of microvascular blood flow in white matter, no data on subcortical capillary blood flow parameters are available, largely due to the lack of appropriate imaging methods. To address this knowledge gap, we employed two-photon microscopy using a far-red fluorophore Alexa680 and photon-counting detection to measure capillary red blood cell (RBC) flux in both cerebral gray and white matter, in isoflurane-anesthetized mice. We have found that in control animals, baseline capillary RBC flux in the white matter was significantly higher than in the adjacent cerebral gray matter. In response to mild hypercapnia, RBC flux in the white matter exhibited significantly smaller fractional increase than in the gray matter. Finally, during global cerebral hypoperfusion, RBC flux in the white matter was reduced significantly in comparison to the controls, while RBC flux in the gray matter was preserved. Our results suggest that blood flow in the white matter may be less efficiently regulated when challenged by physiological perturbations as compared to the gray matter. Importantly, the blood flow in the white matter may be more susceptible to hypoperfusion than in the gray matter, potentially exacerbating the white matter deterioration in brain conditions involving global cerebral hypoperfusion.
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Affiliation(s)
- Baoqiang Li
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Ryo Ohtomo
- Departments of Radiology and Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Martin Thunemann
- Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| | - Stephen R Adams
- Department of Pharmacology, University of California, San Diego, La Jolla, CA, USA
| | - Jing Yang
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Buyin Fu
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Mohammad A Yaseen
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Chongzhao Ran
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Jonathan R Polimeni
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - David A Boas
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Anna Devor
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
- Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
- Department of Radiology, University of California San Diego, La Jolla, CA, USA
| | - Eng H Lo
- Departments of Radiology and Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Ken Arai
- Departments of Radiology and Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Sava Sakadžić
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
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Williams IM, McClatchey PM, Bracy DP, Bonner JS, Valenzuela FA, Wasserman DH. Transendothelial Insulin Transport is Impaired in Skeletal Muscle Capillaries of Obese Male Mice. Obesity (Silver Spring) 2020; 28:303-314. [PMID: 31903723 PMCID: PMC6980999 DOI: 10.1002/oby.22683] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Accepted: 09/27/2019] [Indexed: 12/19/2022]
Abstract
OBJECTIVE The continuous endothelium of skeletal muscle (SkM) capillaries regulates insulin's access to skeletal myocytes. Whether impaired transendothelial insulin transport (EIT) contributes to SkM insulin resistance (IR), however, is unknown. METHODS Male and female C57/Bl6 mice were fed either chow or a high-fat diet for 16 weeks. Intravital microscopy was used to measure EIT in SkM capillaries, electron microscopy to assess endothelial ultrastructure, and glucose tracers to measure indices of glucose metabolism. RESULTS Diet-induced obesity (DIO) male mice were found to have a ~15% reduction in EIT compared with lean mice. Impaired EIT was associated with a 45% reduction in endothelial vesicles. Despite impaired EIT, hyperinsulinemia sustained delivery of insulin to the interstitial space in DIO male mice. Even with sustained interstitial insulin delivery, DIO male mice still showed SkM IR indicating severe myocellular IR in this model. Interestingly, there was no difference in EIT, endothelial ultrastructure, or SkM insulin sensitivity between lean female mice and female mice fed a high-fat diet. CONCLUSIONS These results suggest that, in male mice, obesity results in ultrastructural alterations to the capillary endothelium that delay EIT. Nonetheless, the myocyte appears to exceed the endothelium as a contributor to SkM IR in DIO male mice.
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Affiliation(s)
- Ian M Williams
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | - P Mason McClatchey
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | - Deanna P Bracy
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
- Mouse Metabolic Phenotyping Center, Vanderbilt University, Nashville, Tennessee, USA
| | | | | | - David H Wasserman
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
- Mouse Metabolic Phenotyping Center, Vanderbilt University, Nashville, Tennessee, USA
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Gniesmer S, Brehm R, Hoffmann A, de Cassan D, Menzel H, Hoheisel AL, Glasmacher B, Willbold E, Reifenrath J, Ludwig N, Zimmerer R, Tavassol F, Gellrich NC, Kampmann A. Vascularization and biocompatibility of poly(ε-caprolactone) fiber mats for rotator cuff tear repair. PLoS One 2020; 15:e0227563. [PMID: 31929570 PMCID: PMC6957163 DOI: 10.1371/journal.pone.0227563] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 12/20/2019] [Indexed: 12/22/2022] Open
Abstract
Rotator cuff tear is the most frequent tendon injury in the adult population. Despite current improvements in surgical techniques and the development of grafts, failure rates following tendon reconstruction remain high. New therapies, which aim to restore the topology and functionality of the interface between muscle, tendon and bone, are essentially required. One of the key factors for a successful incorporation of tissue engineered constructs is a rapid ingrowth of cells and tissues, which is dependent on a fast vascularization. The dorsal skinfold chamber model in female BALB/cJZtm mice allows the observation of microhemodynamic parameters in repeated measurements in vivo and therefore the description of the vascularization of different implant materials. In order to promote vascularization of implant material, we compared a porous polymer patch (a commercially available porous polyurethane based scaffold from Biomerix™) with electrospun polycaprolactone (PCL) fiber mats and chitosan-graft-PCL coated electrospun PCL (CS-g-PCL) fiber mats in vivo. Using intravital fluorescence microscopy microcirculatory parameters were analyzed repetitively over 14 days. Vascularization was significantly increased in CS-g-PCL fiber mats at day 14 compared to the porous polymer patch and uncoated PCL fiber mats. Furthermore CS-g-PCL fiber mats showed also a reduced activation of immune cells. Clinically, these are important findings as they indicate that the CS-g-PCL improves the formation of vascularized tissue and the ingrowth of cells into electrospun PCL scaffolds. Especially the combination of enhanced vascularization and the reduction in immune cell activation at the later time points of our study points to an improved clinical outcome after rotator cuff tear repair.
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Affiliation(s)
- Sarah Gniesmer
- Department of Oral and Maxillofacial Surgery, Hannover Medical School, Hannover, Germany
- NIFE—Lower Saxony Centre for Biomedical Engineering, Implant Research and Development, Hannover, Germany
| | - Ralph Brehm
- Institute for Anatomy, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Andrea Hoffmann
- NIFE—Lower Saxony Centre for Biomedical Engineering, Implant Research and Development, Hannover, Germany
- Department of Orthopedic Surgery, Laboratory for Biomechanics and Biomaterials, Graded Implants and Regenerative Strategies, Hannover Medical School, Hannover, Germany
| | - Dominik de Cassan
- Institute for Technical Chemistry, Braunschweig University of Technology, Braunschweig, Germany
| | - Henning Menzel
- Institute for Technical Chemistry, Braunschweig University of Technology, Braunschweig, Germany
| | - Anna Lena Hoheisel
- NIFE—Lower Saxony Centre for Biomedical Engineering, Implant Research and Development, Hannover, Germany
- Institute of Multiphase Processes, Leibniz University Hannover, Hannover, Germany
| | - Birgit Glasmacher
- NIFE—Lower Saxony Centre for Biomedical Engineering, Implant Research and Development, Hannover, Germany
- Institute of Multiphase Processes, Leibniz University Hannover, Hannover, Germany
| | - Elmar Willbold
- NIFE—Lower Saxony Centre for Biomedical Engineering, Implant Research and Development, Hannover, Germany
- Department of Orthopedic Surgery, Hannover Medical School, Hannover, Germany
| | - Janin Reifenrath
- NIFE—Lower Saxony Centre for Biomedical Engineering, Implant Research and Development, Hannover, Germany
- Department of Orthopedic Surgery, Hannover Medical School, Hannover, Germany
| | - Nils Ludwig
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States of America
| | - Ruediger Zimmerer
- Department of Oral and Maxillofacial Surgery, Hannover Medical School, Hannover, Germany
| | - Frank Tavassol
- Department of Oral and Maxillofacial Surgery, Hannover Medical School, Hannover, Germany
| | - Nils-Claudius Gellrich
- Department of Oral and Maxillofacial Surgery, Hannover Medical School, Hannover, Germany
| | - Andreas Kampmann
- Department of Oral and Maxillofacial Surgery, Hannover Medical School, Hannover, Germany
- NIFE—Lower Saxony Centre for Biomedical Engineering, Implant Research and Development, Hannover, Germany
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Ye F, Yin S, Li M, Li Y, Zhong J. In-vivo full-field measurement of microcirculatory blood flow velocity based on intelligent object identification. J Biomed Opt 2020; 25:1-11. [PMID: 31970945 PMCID: PMC6975132 DOI: 10.1117/1.jbo.25.1.016003] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 12/30/2019] [Indexed: 05/09/2023]
Abstract
Microcirculation plays a crucial role in delivering oxygen and nutrients to living tissues and in removing metabolic wastes from the human body. Monitoring the velocity of blood flow in microcirculation is essential for assessing various diseases, such as diabetes, cancer, and critical illnesses. Because of the complex morphological pattern of the capillaries, both In-vivo capillary identification and blood flow velocity measurement by conventional optical capillaroscopy are challenging. Thus, we focused on developing an In-vivo optical microscope for capillary imaging, and we propose an In-vivo full-field flow velocity measurement method based on intelligent object identification. The proposed method realizes full-field blood flow velocity measurements in microcirculation by employing a deep neural network to automatically identify and distinguish capillaries from images. In addition, a spatiotemporal diagram analysis is used for flow velocity calculation. In-vivo experiments were conducted, and the images and videos of capillaries were collected for analysis. We demonstrated that the proposed method is highly accurate in performing full-field blood flow velocity measurements in microcirculation. Further, because this method is simple and inexpensive, it can be effectively employed in clinics.
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Affiliation(s)
- Fei Ye
- Jinan University, Department of Optoelectronic Engineering, Guangzhou, China
| | - Songchao Yin
- Sun Yat-sen University, Third Affiliated Hospital, Department of Dermatology, Guangzhou, China
| | - Meirong Li
- Sun Yat-sen University, Third Affiliated Hospital, Department of Dermatology, Guangzhou, China
| | - Yujie Li
- Sun Yat-sen University, Sixth Affiliated Hospital, Reproductive Medicine Center, Guangzhou, China
| | - Jingang Zhong
- Jinan University, Department of Optoelectronic Engineering, Guangzhou, China
- Address all correspondence to Jingang Zhong, E-mail:
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Aubert V, Kaminski J, Guillaud F, Hauet T, Hannaert P. A Computer Model of Oxygen Dynamics in the Cortex of the Rat Kidney at the Cell-Tissue Level. Int J Mol Sci 2019; 20:E6246. [PMID: 31835730 PMCID: PMC6941061 DOI: 10.3390/ijms20246246] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Revised: 12/02/2019] [Accepted: 12/05/2019] [Indexed: 02/06/2023] Open
Abstract
The renal cortex drives renal function. Hypoxia/reoxygenation are primary factors in ischemia-reperfusion (IR) injuries, but renal oxygenation per se is complex and awaits full elucidation. Few mathematical models address this issue: none captures cortical tissue heterogeneity. Using agent-based modeling, we develop the first model of cortical oxygenation at the cell-tissue level (RCM), based on first principles and careful bibliographical analysis. Entirely parameterized with Rat data, RCM is a morphometrically equivalent 2D-slice of cortical tissue, featuring peritubular capillaries (PTC), tubules and interstitium. It implements hemoglobin/O2 binding-release, oxygen diffusion, and consumption, as well as capillary and tubular flows. Inputs are renal blood flow RBF and PO2 feeds; output is average tissue PO2 (tPO2). After verification and sensitivity analysis, RCM was validated at steady-state (tPO2 37.7 ± 2.2 vs. 36.9 ± 6 mmHg) and under transients (ischemic oxygen half-time: 4.5 ± 2.5 vs. 2.3 ± 0.5 s in situ). Simulations confirm that PO2 is largely independent of RBF, except at low values. They suggest that, at least in the proximal tubule, the luminal flow dominantly contributes to oxygen delivery, while the contribution of capillaries increases under partial ischemia. Before addressing IR-induced injuries, upcoming developments include ATP production, adaptation to minutes-hours scale, and segmental and regional specification.
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Affiliation(s)
| | | | | | | | - Patrick Hannaert
- INSERM U1082-IRTOMIT, 86000 Poitiers, France; (V.A.); (J.K.); (F.G.); (T.H.)
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48
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Connor BW, Carvalho H. Using Dramatization to Teach Starling Forces in the Microcirculation to First-Year Medical Students. MedEdPORTAL 2019; 15:10842. [PMID: 31911933 PMCID: PMC6944257 DOI: 10.15766/mep_2374-8265.10842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 07/09/2019] [Indexed: 06/10/2023]
Abstract
INTRODUCTION The clinical importance, prevalence, and multiple etiologies of tissue edema make it a critical part of medical education. Given the multiple physiological parameters that must be simultaneously considered to determine fluid movement, it is important that a deeper understanding of the microcirculation and fluid shifts is achieved in preclinical education. METHODS We describe an innovative teaching methodology using dramatization to interactively teach Starling forces to first-year medical students. Prior to the dramatization, students were given an introduction to Starling forces. They also completed a brief knowledge quiz on the topic before and after the activity. The classroom walls were marked with signs representing the intravascular space, extravascular or interstitium, and lymphatics compartments. Students were invited to act out or mimic the fluid shifts within capillaries as the values for hydrostatic and colloid osmotic pressures for the intravascular and interstitial spaces were presented. The goal was for each student to decide which compartment he/she would move to as fluid according to Starling force values and/or clinical scenarios. RESULTS A significant improvement between pre- and postactivity quiz performance (45.4% ± 25.1% and 77.5% ± 14.1%, respectively) was observed (n = 26, p < .001, t test). In a postactivity survey, 85% of students reported the activity to be an effective way of learning. DISCUSSION Our data indicate that this dramatization approach is effective in complementing passive learning in traditional lectures. Furthermore, this type of dynamic activity brings joy to the classroom and breaks the monotony of lecturing.
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Affiliation(s)
| | - Helena Carvalho
- Associate Professor, Department of Basic Science Education, Virginia Tech Carilion School of Medicine
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Abstract
Recent progress on bioresorbable and bio-compatible miniature systems provides prospects for developing novel nanorobots operating inside the human body. These nanoscale systems are expected to dissolve in vivo and cause no side effect after completing their tasks. Motivated by these advancements, we have developed the analytical framework of touchable molecular communication (TouchCom) to describe the process of direct drug targeting (DDT) using externally controllable nanorobots. Built upon our previous work, we develop a novel latticed channel model of TouchCom for an interconnected capillary network near a targeted tumor area. Specifically, we propose a two-dimensional grid to synthesize the microcirculation environment, which is used to describe the propagation process of nanorobots. Furthermore, by applying the concept of multiple-input multiple-output (MIMO) systems in wireless communications to the therapeutic window in cancer treatment, we propose a MIMO DDT strategy in the latticed channel to enhance the targeting efficiency while minimizing the adverse effect of drug toxicity. Based on the proposed model, we study the influence of blood flow direction on the efficiency of DDT, and introduce a compensation strategy with the help of an external guiding field to mitigate the misalignment between the direction of blood flow and the tumor location.
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50
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Schmid F, Barrett MJP, Obrist D, Weber B, Jenny P. Red blood cells stabilize flow in brain microvascular networks. PLoS Comput Biol 2019; 15:e1007231. [PMID: 31469820 PMCID: PMC6750893 DOI: 10.1371/journal.pcbi.1007231] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 09/18/2019] [Accepted: 07/01/2019] [Indexed: 12/28/2022] Open
Abstract
Capillaries are the prime location for oxygen and nutrient exchange in all tissues. Despite their fundamental role, our knowledge of perfusion and flow regulation in cortical capillary beds is still limited. Here, we use in vivo measurements and blood flow simulations in anatomically accurate microvascular network to investigate the impact of red blood cells (RBCs) on microvascular flow. Based on these in vivo and in silico experiments, we show that the impact of RBCs leads to a bias toward equating the values of the outflow velocities at divergent capillary bifurcations, for which we coin the term “well-balanced bifurcations”. Our simulation results further reveal that hematocrit heterogeneity is directly caused by the RBC dynamics, i.e. by their unequal partitioning at bifurcations and their effect on vessel resistance. These results provide the first in vivo evidence of the impact of RBC dynamics on the flow field in the cortical microvasculature. By structural and functional analyses of our blood flow simulations we show that capillary diameter changes locally alter flow and RBC distribution. A dilation of 10% along a vessel length of 100 μm increases the flow on average by 21% in the dilated vessel downstream a well-balanced bifurcation. The number of RBCs rises on average by 27%. Importantly, RBC up-regulation proves to be more effective the more balanced the outflow velocities at the upstream bifurcation are. Taken together, we conclude that diameter changes at capillary level bear potential to locally change the flow field and the RBC distribution. Moreover, our results suggest that the balancing of outflow velocities contributes to the robustness of perfusion. Based on our in silico results, we anticipate that the bi-phasic nature of blood and small-scale regulations are essential for a well-adjusted oxygen and energy substrate supply. Glucose and oxygen are key energy sources of the brain. As energy storage capabilities are limited in the brain, a continuous supply of oxygen and glucose via the bloodstream is crucial for the brain’s functioning. The bulk of discharge occurs at the level of capillaries, which are the smallest and most frequent vessels of the cortical vasculature. Nonetheless, our understanding of perfusion and topology of the capillary bed is still limited. Here, we use in vivo two-photon based blood flow measurements and numerical simulations in large realistic microvascular networks to study the flow in the cortical microvasculature. Our results reveal that the impact of red blood cells enhances the robustness of microvascular perfusion and increases the heterogeneity in red blood cell distribution. It is well established that higher neuronal activity leads to an increase in blood flow. However, the precise regulation mechanisms and their spatial extent remain largely unknown. We show that small-scale regulations locally alter flow and red blood cell distribution. We suggest that these mechanisms are key for an efficient and flexible circulatory system. Moreover, our results reveal a novel role of the bi-phasic nature of blood.
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Affiliation(s)
- Franca Schmid
- Institute of Fluid Dynamics, ETH Zurich, Sonneggstrasse 3, Zurich, Switzerland
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, Zurich, Switzerland
- * E-mail:
| | - Matthew J. P. Barrett
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, Zurich, Switzerland
- Neuroscience Center Zurich, University and ETH Zurich, Winterthurerstrasse 190, Zurich, Switzerland
| | - Dominik Obrist
- ARTORG Center for Biomedical Engineering Research, University of Bern, Murtenstrasse 50, Bern, Switzerland
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, Zurich, Switzerland
- Neuroscience Center Zurich, University and ETH Zurich, Winterthurerstrasse 190, Zurich, Switzerland
| | - Patrick Jenny
- Institute of Fluid Dynamics, ETH Zurich, Sonneggstrasse 3, Zurich, Switzerland
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