1
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Bucciarelli A, Mantegazza A, Haeberlin A, Obrist D. Relation between hematocrit partitioning and red blood cell lingering in a microfluidic network. Biophys J 2024; 123:3355-3365. [PMID: 39104120 DOI: 10.1016/j.bpj.2024.07.042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Revised: 07/05/2024] [Accepted: 07/31/2024] [Indexed: 08/07/2024] Open
Abstract
Despite increased interest in the effect of lingering red blood cells (LRBCs) on the heterogeneous hematocrit distribution in the microcirculation, quantitative data on LRBCs before and after the lingering event are still limited. The aim of the study was to investigate the relation between red blood cell (RBC) lingering and hematocrit partitioning in a microfluidic model of a microvascular bifurcation in the limit of low hematocrit conditions (tube hematocrit <10%). To this end, the classification of LRBCs was performed based on timing, position, and velocity of the RBCs. The investigation provided statistical information on the velocity, shape, and orientation of LRBCs as well as on their lateral distribution in the parent and daughter vessels. LRBCs traveled predominantly close to the centerline of the parent vessel, but they marginated close to the distal wall in the daughter vessels. Differently than the RBC flow observed in the smallest vessels, no influence of lingering events on the local hematocrit partitioning was observed in our experiments. However, importantly, we found that LRBCs flowing in the daughter vessel after lingering may be connected to reverse hematocrit partitioning in downstream bifurcations by influencing the skewness of the hematocrit distribution in the daughter vessel, which relates to the so-called network history effect.
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Affiliation(s)
- Aurelia Bucciarelli
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland.
| | - Alberto Mantegazza
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland; Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy
| | - Andreas Haeberlin
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland; Department of Cardiology, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Dominik Obrist
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
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2
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Gholivand A, Korculanin O, Dahlhoff K, Babaki M, Dickscheid T, Lettinga MP. Effect of in-plane and out-of-plane bifurcated microfluidic channels on the flow of aggregating red blood cells. LAB ON A CHIP 2024; 24:2317-2326. [PMID: 38545688 DOI: 10.1039/d4lc00151f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
The blood flow through our microvascular system is a renowned difficult process to understand because the complex flow behavior of blood is intertwined with the complex geometry it has to flow through. Conventional 2D microfluidics has provided important insights, but progress is hampered by the limitation of 2-D confinement. Here we use selective laser-induced etching to excavate non-planar 3-D microfluidic channels in glass that consist of two generations of bifurcations, heading towards more physiological geometries. We identify a cross-talk between the first and second bifurcation only when both bifurcations are in the same plane, as observed in 2D microfluidics. Contrarily, the flow in the branch where the second bifurcation is perpendicular to the first is hardly affected by the initial distortion. This difference in flow behavior is only observed when red blood cells are aggregated, due to the presence of dextran, and disappears by increasing the distance between both generations of bifurcations. Thus, 3-D structures scramble in-plane flow distortions, exemplifying the importance of experimenting with truly 3D microfluidic designs in order to understand complex physiological flow behavior.
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Affiliation(s)
- Amirreza Gholivand
- Biomacromolecular Systems and Processes (IBI-4), Research Centre Jülich, 52425 Jülich, Germany.
- Laboratory for Soft Matter and Biophysics, KU Leuven, B-3001 Leuven, Belgium
| | - Olivera Korculanin
- Ernst-Ruska Centre for Microscopy and Spectroscopy with Electrons (ER-C-3 Structural Biology), Research Centre Jülich, 52425 Jülich, Germany
- AG Biophysik, I. Physikalisches Institut (IA), RWTH Aachen University, 52074 Aachen, Germany
| | - Knut Dahlhoff
- Central Institute of Engineering, Electronics and Analytics (ZEA-1), Research Centre Jülich, 52425 Jülich, Germany
| | - Mehrnaz Babaki
- Biomacromolecular Systems and Processes (IBI-4), Research Centre Jülich, 52425 Jülich, Germany.
- Laboratory for Soft Matter and Biophysics, KU Leuven, B-3001 Leuven, Belgium
| | - Timo Dickscheid
- Institute of Neuroscience and Medicine (INM-1), Research Centre Jülich, 52425 Jülich, Germany
- Institute of Computer Science, Heinrich Heine University Düsseldorf, Germany
- Helmholtz AI, Research Centre Jülich, 52425 Jülich, Germany
| | - Minne Paul Lettinga
- Biomacromolecular Systems and Processes (IBI-4), Research Centre Jülich, 52425 Jülich, Germany.
- Laboratory for Soft Matter and Biophysics, KU Leuven, B-3001 Leuven, Belgium
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3
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Stathoulopoulos A, Passos A, Kaliviotis E, Balabani S. Partitioning of dense RBC suspensions in single microfluidic bifurcations: role of cell deformability and bifurcation angle. Sci Rep 2024; 14:535. [PMID: 38177195 PMCID: PMC10767057 DOI: 10.1038/s41598-023-49849-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 12/12/2023] [Indexed: 01/06/2024] Open
Abstract
Red blood cells (RBCs) are a key determinant of human physiology and their behaviour becomes extremely heterogeneous as they navigate in narrow, bifurcating vessels in the microvasculature, affecting local haemodynamics. This is due to partitioning in bifurcations which is dependent on the biomechanical properties of RBCs, especially deformability. We examine the effect of deformability on the haematocrit distributions of dense RBC suspensions flowing in a single, asymmetric Y-shaped bifurcation, experimentally. Human RBC suspensions (healthy and artificially hardened) at 20% haematocrit (Ht) were perfused through the microchannels at different flow ratios between the outlet branches, and negligible inertia, and imaged to infer cell distributions. Notable differences in the shape of the haematocrit distributions were observed between healthy and hardened RBCs near the bifurcation apex. These lead to more asymmetric distributions for healthy RBCs in the daughter and outlet branches with cells accumulating near the inner channel walls, exhibiting distinct hematocrit peaks which are sharper for healthy RBCs. Although the hematocrit distributions differed locally, similar partitioning characteristics were observed for both suspensions. Comparisons with RBC distributions measured in a T-shaped bifurcation showed that the bifurcation angle affects the haematocrit characteristics of the healthy RBCs and not the hardened ones. The extent of RBC partitioning was found similar in both geometries and suspensions. The study highlights the differences between local and global characteristics which impact RBC distribution in more complex, multi-bifurcation networks.
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Affiliation(s)
- Antonios Stathoulopoulos
- FluME, Department of Mechanical Engineering, University College London (UCL), London, WC1E 7JE, UK
| | - Andreas Passos
- FluME, Department of Mechanical Engineering, University College London (UCL), London, WC1E 7JE, UK
- Department of Mechanical Engineering and Material Science Engineering, Cyprus University of Technology, Limassol, Cyprus
| | - Efstathios Kaliviotis
- Department of Mechanical Engineering and Material Science Engineering, Cyprus University of Technology, Limassol, Cyprus
| | - Stavroula Balabani
- FluME, Department of Mechanical Engineering, University College London (UCL), London, WC1E 7JE, UK.
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London (UCL), London, UK.
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4
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Rashidi Y, Aouane O, Darras A, John T, Harting J, Wagner C, Recktenwald SM. Cell-free layer development and spatial organization of healthy and rigid red blood cells in a microfluidic bifurcation. SOFT MATTER 2023; 19:6255-6266. [PMID: 37522517 DOI: 10.1039/d3sm00517h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/01/2023]
Abstract
Bifurcations and branches in the microcirculation dramatically affect blood flow as they determine the spatiotemporal organization of red blood cells (RBCs). Such changes in vessel geometries can further influence the formation of a cell-free layer (CFL) close to the vessel walls. Biophysical cell properties, such as their deformability, which is impaired in various diseases, are often thought to impact blood flow and affect the distribution of flowing RBCs. This study investigates the flow behavior of healthy and artificially hardened RBCs in a bifurcating microfluidic T-junction. We determine the RBC distribution across the channel width at multiple positions before and after the bifurcation. Thus, we reveal distinct focusing profiles in the feeding mother channel for rigid and healthy RBCs that dramatically impact the cell organization in the successive daughter channels. Moreover, we experimentally show how the characteristic asymmetric CFLs in the daughter vessels develop along their flow direction. Complimentary numerical simulations indicate that the buildup of the CFL is faster for healthy than for rigid RBCs. Our results provide fundamental knowledge to understand the partitioning of rigid RBC as a model of cells with pathologically impaired deformability in complex in vitro networks.
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Affiliation(s)
- Yazdan Rashidi
- Dynamics of Fluids, Department of Experimental Physics, Saarland University, 66123 Saarbrücken, Germany.
| | - Othmane Aouane
- Helmholtz Institute Erlangen-Nürnberg for Renewable Energy, Forschungszentrum Jülich, 91058 Erlangen, Germany
| | - Alexis Darras
- Dynamics of Fluids, Department of Experimental Physics, Saarland University, 66123 Saarbrücken, Germany.
| | - Thomas John
- Dynamics of Fluids, Department of Experimental Physics, Saarland University, 66123 Saarbrücken, Germany.
| | - Jens Harting
- Helmholtz Institute Erlangen-Nürnberg for Renewable Energy, Forschungszentrum Jülich, 91058 Erlangen, Germany
- Department of Chemical and Biological Engineering and Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Christian Wagner
- Dynamics of Fluids, Department of Experimental Physics, Saarland University, 66123 Saarbrücken, Germany.
- Department of Physics and Materials Science, University of Luxembourg, 1511 Luxembourg City, Luxembourg
| | - Steffen M Recktenwald
- Dynamics of Fluids, Department of Experimental Physics, Saarland University, 66123 Saarbrücken, Germany.
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5
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Rashidi Y, Simionato G, Zhou Q, John T, Kihm A, Bendaoud M, Krüger T, Bernabeu MO, Kaestner L, Laschke MW, Menger MD, Wagner C, Darras A. Red blood cell lingering modulates hematocrit distribution in the microcirculation. Biophys J 2023; 122:1526-1537. [PMID: 36932676 PMCID: PMC10147840 DOI: 10.1016/j.bpj.2023.03.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 02/04/2023] [Accepted: 03/13/2023] [Indexed: 03/18/2023] Open
Abstract
The distribution of red blood cells (RBCs) in the microcirculation determines the oxygen delivery and solute transport to tissues. This process relies on the partitioning of RBCs at successive bifurcations throughout the microvascular network, and it has been known since the last century that RBCs partition disproportionately to the fractional blood flow rate, therefore leading to heterogeneity of the hematocrit (i.e., volume fraction of RBCs in blood) in microvessels. Usually, downstream of a microvascular bifurcation, the vessel branch with a higher fraction of blood flow receives an even higher fraction of RBC flux. However, both temporal and time-average deviations from this phase-separation law have been observed in recent studies. Here, we quantify how the microscopic behavior of RBC lingering (i.e., RBCs temporarily residing near the bifurcation apex with diminished velocity) influences their partitioning, through combined in vivo experiments and in silico simulations. We developed an approach to quantify the cell lingering at highly confined capillary-level bifurcations and demonstrate that it correlates with deviations of the phase-separation process from established empirical predictions by Pries et al. Furthermore, we shed light on how the bifurcation geometry and cell membrane rigidity can affect the lingering behavior of RBCs; e.g., rigid cells tend to linger less than softer ones. Taken together, RBC lingering is an important mechanism that should be considered when studying how abnormal RBC rigidity in diseases such as malaria and sickle-cell disease could hinder the microcirculatory blood flow or how the vascular networks are altered under pathological conditions (e.g., thrombosis, tumors, aneurysm).
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Affiliation(s)
- Yazdan Rashidi
- Experimental Physics, Saarland University, Saarbruecken, Germany.
| | - Greta Simionato
- Experimental Physics, Saarland University, Saarbruecken, Germany; Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| | - Qi Zhou
- School of Engineering, Institute for Multiscale Thermofluids, University of Edinburgh, Edinburgh, United Kingdom
| | - Thomas John
- Experimental Physics, Saarland University, Saarbruecken, Germany
| | - Alexander Kihm
- Experimental Physics, Saarland University, Saarbruecken, Germany
| | - Mohammed Bendaoud
- Experimental Physics, Saarland University, Saarbruecken, Germany; Université Grenoble Alpes, CNRS, LIPhy, Grenoble, France; LaMCScI, Faculty of Sciences, Mohammed V University of Rabat, Rabat, Morocco
| | - Timm Krüger
- School of Engineering, Institute for Multiscale Thermofluids, University of Edinburgh, Edinburgh, United Kingdom
| | - Miguel O Bernabeu
- Centre for Medical Informatics, Usher Institute, University of Edinburgh, Edinburgh, United Kingdom; The Bayes Centre, University of Edinburgh, Edinburgh, United Kingdom
| | - Lars Kaestner
- Experimental Physics, Saarland University, Saarbruecken, Germany; Theoretical Medicine and Biosciences, Saarland University, Homburg, Germany
| | - Matthias W Laschke
- Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| | - Michael D Menger
- Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| | - Christian Wagner
- Experimental Physics, Saarland University, Saarbruecken, Germany; Physics and Materials Science Research Unit, University of Luxembourg, Luxembourg, Luxembourg
| | - Alexis Darras
- Experimental Physics, Saarland University, Saarbruecken, Germany.
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6
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Merlo A, Losserand S, Yaya F, Connes P, Faivre M, Lorthois S, Minetti C, Nader E, Podgorski T, Renoux C, Coupier G, Franceschini E. Influence of storage and buffer composition on the mechanical behavior of flowing red blood cells. Biophys J 2023; 122:360-373. [PMID: 36476993 PMCID: PMC9892622 DOI: 10.1016/j.bpj.2022.12.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 10/17/2022] [Accepted: 12/01/2022] [Indexed: 12/12/2022] Open
Abstract
On-chip study of blood flow has emerged as a powerful tool to assess the contribution of each component of blood to its overall function. Blood has indeed many functions, from gas and nutrient transport to immune response and thermal regulation. Red blood cells play a central role therein, in particular through their specific mechanical properties, which directly influence pressure regulation, oxygen perfusion, or platelet and white cell segregation toward endothelial walls. As the bloom of in-vitro studies has led to the apparition of various storage and sample preparation protocols, we address the question of the robustness of the results involving cell mechanical behavior against this diversity. The effects of three conservation media (EDTA, citrate, and glucose-albumin-sodium-phosphate) and storage time on the red blood cell mechanical behavior are assessed under different flow conditions: cell deformability by ektacytometry, shape recovery of cells flowing out of a microfluidic constriction, and cell-flipping dynamics under shear flow. The impact of buffer solutions (phosphate-buffered saline and density-matched suspension using iodixanol/Optiprep) are also studied by investigating individual cell-flipping dynamics, relative viscosity of cell suspensions, and cell structuration under Poiseuille flow. Our results reveal that storing blood samples up to 7 days after withdrawal and suspending them in adequate density-matched buffer solutions has, in most experiments, a moderate effect on the overall mechanical response, with a possible rapid evolution in the first 3 days after sample collection.
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Affiliation(s)
- Adlan Merlo
- GDR MECABIO, France; Institut de Mécanique des Fluides de Toulouse (IMFT), Université de Toulouse, CNRS, Toulouse, France; Biomechanics and Bioengineering Laboratory (UMR 7338), Université de Technologie de Compiègne - CNRS, Compiègne, France
| | - Sylvain Losserand
- GDR MECABIO, France; Université Grenoble Alpes, CNRS, LIPhy, Grenoble, France
| | - François Yaya
- GDR MECABIO, France; Université Grenoble Alpes, CNRS, LIPhy, Grenoble, France
| | - Philippe Connes
- GDR MECABIO, France; Team 'Vascular Biology and Red Blood Cell', Laboratoire Interuniversitaire de Biologie de la Motricité (LIBM) EA7424, Université Claude Bernard Lyon 1, Université de Lyon, Villeurbanne, France; Laboratoire d'Excellence du Globule Rouge (Labex GR-Ex), PRES Sorbonne, Paris, France
| | - Magalie Faivre
- GDR MECABIO, France; University Lyon, CNRS, INSA Lyon, Ecole Centrale de Lyon, Université Claude Bernard Lyon 1, CPE Lyon, INL, UMR5270, Villeurbanne, France
| | - Sylvie Lorthois
- GDR MECABIO, France; Institut de Mécanique des Fluides de Toulouse (IMFT), Université de Toulouse, CNRS, Toulouse, France
| | - Christophe Minetti
- Aero Thermo Mechanics CP 165/43, Université libre de Bruxelles, Brussels, Belgium
| | - Elie Nader
- GDR MECABIO, France; Team 'Vascular Biology and Red Blood Cell', Laboratoire Interuniversitaire de Biologie de la Motricité (LIBM) EA7424, Université Claude Bernard Lyon 1, Université de Lyon, Villeurbanne, France; Laboratoire d'Excellence du Globule Rouge (Labex GR-Ex), PRES Sorbonne, Paris, France
| | - Thomas Podgorski
- GDR MECABIO, France; Université Grenoble Alpes, CNRS, LIPhy, Grenoble, France; Université Grenoble Alpes, CNRS, Grenoble INP, LRP, Grenoble, France
| | - Céline Renoux
- GDR MECABIO, France; Team 'Vascular Biology and Red Blood Cell', Laboratoire Interuniversitaire de Biologie de la Motricité (LIBM) EA7424, Université Claude Bernard Lyon 1, Université de Lyon, Villeurbanne, France; Laboratoire d'Excellence du Globule Rouge (Labex GR-Ex), PRES Sorbonne, Paris, France; Service de biochimie et biologie moléculaire, Hospices Civils de Lyon, Lyon, France
| | - Gwennou Coupier
- GDR MECABIO, France; Université Grenoble Alpes, CNRS, LIPhy, Grenoble, France.
| | - Emilie Franceschini
- GDR MECABIO, France; Aix-Marseille University, CNRS, Centrale Marseille, LMA, Turing Center for Living Systems, Marseille, France.
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7
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Pskowski A, Bagchi P, Zahn JD. Hematocrit skewness along sequential bifurcations within a microfluidic network induces significant changes in downstream red blood cell partitioning. BIOMICROFLUIDICS 2022; 16:064104. [PMID: 36483019 PMCID: PMC9726222 DOI: 10.1063/5.0110235] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 11/15/2022] [Indexed: 06/17/2023]
Abstract
There has been a wealth of research conducted regarding the partitioning of red blood cells (RBCs) at bifurcations within the microvasculature. In previous studies, partitioning has been characterized as either regular partitioning, in which the higher flow rate daughter channel receives a proportionally larger percentage of RBCs, or reverse partitioning, in which the opposite occurs. While there are many examples of network studies in silico, most in vitro work has been conducted using single bifurcation. When microfluidic networks have been used, the channel dimensions are typically greater than 20 μm, ignoring conditions where RBCs are highly confined. This paper presents a study of RBC partitioning in a network of sequential bifurcations with channel dimensions less than 8 μm in hydraulic diameter. The study investigated the effect of the volumetric flow rate ratio (Q*) at each bifurcation, solution hematocrit, and channel length on the erythrocyte flux ratio (N*), a measure of RBC partitioning. We report significant differences in partitioning between upstream and downstream bifurcations even when the flow rate ratio remains the same. Skewness analysis, a measure of cell distribution across the width of a vessel, strongly suggests that immediately following the first bifurcation most RBCs are skewed toward the inner channel wall, leading to preferential RBC perfusion into one daughter channel at the subsequent bifurcation even at higher downstream flow rate ratios. The skewness of RBC distribution following the first bifurcation can either manifest as enhanced regular partitioning or reverse partitioning at the succeeding branch.
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Affiliation(s)
- Andrew Pskowski
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA
| | - Prosenjit Bagchi
- Department of Mechanical and Aerospace Engineering, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA
| | - Jeffrey D. Zahn
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA
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8
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Ghanbarzadeh-Dagheyan A, Nili VA, Ejtehadi M, Savabi R, Kavehvash Z, Ahmadian MT, Vahdat BV. Time-domain ultrasound as prior information for frequency-domain compressive ultrasound for intravascular cell detection: A 2-cell numerical model. ULTRASONICS 2022; 125:106791. [PMID: 35809517 DOI: 10.1016/j.ultras.2022.106791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Revised: 05/05/2022] [Accepted: 06/08/2022] [Indexed: 06/15/2023]
Abstract
This study proposes a new method for the detection of a weak scatterer among strong scatterers using prior-information ultrasound (US) imaging. A perfect application of this approach is in vivo cell detection in the bloodstream, where red blood cells (RBCs) serve as identifiable strong scatterers. In vivo cell detection can help diagnose cancer at its earliest stages, increasing the chances of survival for patients. This work combines time-domain US with frequency-domain compressive US imaging to detect a 20-μ MCF-7 circulating tumor cell (CTC) among a number of RBCs within a simulated venule inside the mouth. The 2D image reconstructed from the time-domain US is employed to simulate the reflected and scattered pressure field from the RBCs, which is then measured at the location of the receivers. The RBCs are tagged one time by a human operator and another time, automatically, by template-based computer vision. Next, the resulting signal from the RBCs is subtracted from the measured total signal in frequency domain to generate the scattered-field data, coming from the CTC alone. Feeding that signal and the background pressure field into a norm-one-based compressive sensing code enables detecting the CTC at various locations. As errors could arise in determining the location of the RBCs and their acoustic properties in the real world, small errors (up to 10% in the former and 5% in the latter) are purposefully introduced to the model, to which the proposed method is shown to be resilient. Localization errors are smaller than 12 μ when a human tags the RBCs and smaller than 25 μ when computer vision is applied. Despite its limitations, this study, for the first time, reports the results of combining two US modalities aimed at cell detection and introduces a unique and useful application for ultrahigh-frequency US imaging. It should be noted that this method can be used in detecting weak scatterers with ultrasound waves in other applications as well.
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Affiliation(s)
- Ashkan Ghanbarzadeh-Dagheyan
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran; Department of Electrical Engineering, Sharif University of Technology, Tehran, Iran.
| | - Vahid Amin Nili
- Department of Electrical Engineering, Sharif University of Technology, Tehran, Iran
| | - Mehdi Ejtehadi
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
| | - Reza Savabi
- School of Mechanical Engineering, University of Tehran, Tehran, Iran
| | - Zahra Kavehvash
- Department of Electrical Engineering, Sharif University of Technology, Tehran, Iran
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9
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Stathoulopoulos A, Passos A, Balabani S. Flows of healthy and hardened RBC suspensions through a micropillar array. Med Eng Phys 2022; 107:103874. [DOI: 10.1016/j.medengphy.2022.103874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 07/29/2022] [Accepted: 08/09/2022] [Indexed: 11/25/2022]
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10
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A computational study of red blood cell deformability effect on hemodynamic alteration in capillary vessel networks. Sci Rep 2022; 12:4304. [PMID: 35277592 PMCID: PMC8917159 DOI: 10.1038/s41598-022-08357-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Accepted: 03/07/2022] [Indexed: 01/12/2023] Open
Abstract
Capillary blood vessels, the smallest vessels in the body, form an intricate network with constantly bifurcating, merging and winding vessels. Red blood cells (RBCs) must navigate through such complex microvascular networks in order to maintain tissue perfusion and oxygenation. Normal, healthy RBCs are extremely deformable and able to easily flow through narrow vessels. However, RBC deformability is reduced in many pathological conditions and during blood storage. The influence of reduced cell deformability on microvascular hemodynamics is not well established. Here we use a high-fidelity, 3D computational model of blood flow that retains exact geometric details of physiologically realistic microvascular networks, and deformation of every one of nearly a thousand RBCs flowing through the networks. We predict that reduced RBC deformability alters RBC trafficking with significant and heterogeneous changes in hematocrit. We quantify such changes along with RBC partitioning and lingering at vascular bifurcations, perfusion and vascular resistance, and wall shear stress. We elucidate the cellular-scale mechanisms that cause such changes. We show that such changes arise primarily due to the altered RBC dynamics at vascular bifurcations, as well as cross-stream migration. Less deformable cells tend to linger less at majority of bifurcations increasing the fraction of RBCs entering the higher flow branches. Changes in vascular resistance also seen to be heterogeneous and correlate with hematocrit changes. Furthermore, alteration in RBC dynamics is shown to cause localized changes in wall shear stress within vessels and near vascular bifurcations. Such heterogeneous and focal changes in hemodynamics may be the cause of morphological abnormalities in capillary vessel networks as observed in several diseases.
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11
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Franzetti G, Bonfanti M, Homer-Vanniasinkam S, Diaz-Zuccarini V, Balabani S. Experimental evaluation of the patient-specific haemodynamics of an aortic dissection model using particle image velocimetry. J Biomech 2022; 134:110963. [PMID: 35151036 PMCID: PMC9617468 DOI: 10.1016/j.jbiomech.2022.110963] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 12/05/2021] [Accepted: 01/14/2022] [Indexed: 11/15/2022]
Abstract
Aortic Dissection (AD) is a complex pathology that affects the aorta. Diagnosis, management and treatment remain a challenge as it is a highly patient-specific pathology and there is still a limited understanding of the fluid-mechanics phenomena underlying clinical outcomes. Although in vitro models can allow the accurate study of AD flow fields in physical phantoms, they are currently scarce and almost exclusively rely on over simplifying assumptions. In this work, we present the first experimental study of a patient-specific case of AD. An anatomically correct phantom was produced and combined with a state-of-the-art in vitro platform, informed by clinical data, employed to accurately reproduce personalised conditions. The complex AD haemodynamics reproduced by the platform was characterised by flow rate and pressure acquisitions as well as Particle Image Velocimetry (PIV) derived velocity fields. Clinically relevant haemodynamic indices, that can be correlated with AD prognosis - such as velocity, shear rate, turbulent kinetic energy distributions - were extracted in two regions of interest in the aortic domain. The acquired data highlighted the complex nature of the flow (e.g. recirculation regions, low shear rate in the false lumen) and was in very good agreement with the available clinical data and the CFD results of a study conducted alongside, demonstrating the accuracy of the findings. These results demonstrate that the described platform constitutes a powerful, unique tool to reproduce in vitro personalised haemodynamic conditions, which can be used to support the evaluation of surgical procedures, medical devices testing and to validate state-of-the-art numerical models.
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Affiliation(s)
- Gaia Franzetti
- Department of Mechanical Engineering, University College London, London, UK
| | - Mirko Bonfanti
- Department of Mechanical Engineering, University College London, London, UK; Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS), Department of Medical Physics and Biomedical Engineering, University College London, London, UK
| | - Shervanthi Homer-Vanniasinkam
- Department of Mechanical Engineering, University College London, London, UK; Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS), Department of Medical Physics and Biomedical Engineering, University College London, London, UK; Leeds Teaching Hospitals NHS Trust, Leeds, UK
| | - Vanessa Diaz-Zuccarini
- Department of Mechanical Engineering, University College London, London, UK; Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS), Department of Medical Physics and Biomedical Engineering, University College London, London, UK
| | - Stavroula Balabani
- Department of Mechanical Engineering, University College London, London, UK; Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS), Department of Medical Physics and Biomedical Engineering, University College London, London, UK.
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12
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van Batenburg-Sherwood J, Balabani S. Continuum microhaemodynamics modelling using inverse rheology. Biomech Model Mechanobiol 2022; 21:335-361. [PMID: 34907491 PMCID: PMC8807439 DOI: 10.1007/s10237-021-01537-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 11/23/2021] [Indexed: 11/03/2022]
Abstract
Modelling blood flow in microvascular networks is challenging due to the complex nature of haemorheology. Zero- and one-dimensional approaches cannot reproduce local haemodynamics, and models that consider individual red blood cells (RBCs) are prohibitively computationally expensive. Continuum approaches could provide an efficient solution, but dependence on a large parameter space and scarcity of experimental data for validation has limited their application. We describe a method to assimilate experimental RBC velocity and concentration data into a continuum numerical modelling framework. Imaging data of RBCs were acquired in a sequentially bifurcating microchannel for various flow conditions. RBC concentration distributions were evaluated and mapped into computational fluid dynamics simulations with rheology prescribed by the Quemada model. Predicted velocities were compared to particle image velocimetry data. A subset of cases was used for parameter optimisation, and the resulting model was applied to a wider data set to evaluate model efficacy. The pre-optimised model reduced errors in predicted velocity by 60% compared to assuming a Newtonian fluid, and optimisation further reduced errors by 40%. Asymmetry of RBC velocity and concentration profiles was demonstrated to play a critical role. Excluding asymmetry in the RBC concentration doubled the error, but excluding spatial distributions of shear rate had little effect. This study demonstrates that a continuum model with optimised rheological parameters can reproduce measured velocity if RBC concentration distributions are known a priori. Developing this approach for RBC transport with more network configurations has the potential to provide an efficient approach for modelling network-scale haemodynamics.
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Affiliation(s)
| | - Stavroula Balabani
- Department of Mechanical Engineering, University College London, London, UK
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13
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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] [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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14
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Annio G, Torii R, Ducci A, Muthurangu V, Tsang V, Burriesci G. Experimental Validation of Enhanced Magnetic Resonance Imaging (EMRI) Using Particle Image Velocimetry (PIV). Ann Biomed Eng 2021; 49:3481-3493. [PMID: 34181130 DOI: 10.1007/s10439-021-02811-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 06/07/2021] [Indexed: 12/27/2022]
Abstract
Flow-sensitive four-dimensional Cardiovascular Magnetic Resonance Imaging (4D Flow CMR) has increasingly been utilised to characterise patients' blood flow, in association with patiens' state of health and disease, even though spatial and temporal resolutions still constitute a limit. Computational fluid dynamics (CFD) is a powerful tool that could expand these information and, if integrated with experimentally-obtained velocity fields, would enable to derive a large variety of the flow descriptors of interest. However, the accuracy of the flow parameters is highly influenced by the quality of the input data such as the anatomical model and boundary conditions typically derived from medical images including 4D Flow CMR. We previously proposed a novel approach in which 4D Flow CMR and CFD velocity fields are integrated to obtain an Enhanced 4D Flow CMR (EMRI), allowing to overcome the spatial-resolution limitation of 4D Flow CMR, and enable an accurate quantification of flow. In this paper, the proposed approach is validated in a U bend channel, an idealised model of the human aortic arch. The flow patterns were studied with 4D Flow CMR, CFD and EMRI, and compared with high resolution 2D PIV experiments obtained in pulsatile conditions. The main strengths and limitations of 4D Flow CMR and CFD were illustrated by exploiting the accuracy of PIV by comparing against PIV velocity fields. EMRI flow patterns showed a better qualitative and quantitative agreement with PIV results than the other techniques. EMRI enables to overcome the experimental limitations of MRI-based velocity measurements and the modelling simplifications of CFD, allowing an accurate prediction of complex flow patterns observed experimentally, while satisfying mass and momentum balance equations.
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Affiliation(s)
- Giacomo Annio
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK.
| | - Ryo Torii
- Department of Mechanical Engineering, University College London, London, UK.
| | - Andrea Ducci
- Department of Mechanical Engineering, University College London, London, UK
| | - Vivek Muthurangu
- Centre for Cardiovascular Imaging and Physics, University College London, London, UK
| | - Victor Tsang
- Cardiothoracic Surgery Unit, Great Ormond Street Hospital, London, UK
| | - Gaetano Burriesci
- Department of Mechanical Engineering, University College London, London, UK.
- Ri.MED Foundation, Palermo, Italy.
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15
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Compressed vessels bias red blood cell partitioning at bifurcations in a hematocrit-dependent manner: Implications in tumor blood flow. Proc Natl Acad Sci U S A 2021; 118:2025236118. [PMID: 34140409 DOI: 10.1073/pnas.2025236118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The tumor microenvironment is abnormal and associated with tumor tissue hypoxia, immunosuppression, and poor response to treatment. One important abnormality present in tumors is vessel compression. Vessel decompression has been shown to increase survival rates in animal models via enhanced and more homogeneous oxygenation. However, our knowledge of the biophysical mechanisms linking tumor decompression to improved tumor oxygenation is limited. In this study, we propose a computational model to investigate the impact of vessel compression on red blood cell (RBC) dynamics in tumor vascular networks. Our results demonstrate that vessel compression can alter RBC partitioning at bifurcations in a hematocrit-dependent and flow rate-independent manner. We identify RBC focusing due to cross-streamline migration as the mechanism responsible and characterize the spatiotemporal recovery dynamics controlling downstream partitioning. Based on this knowledge, we formulate a reduced-order model that will help future research to elucidate how these effects propagate at a whole vascular network level. These findings contribute to the mechanistic understanding of hemodilution in tumor vascular networks and oxygen homogenization following pharmacological solid tumor decompression.
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16
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Zhou Q, Perovic T, Fechner I, Edgar LT, Hoskins PR, Gerhardt H, Krüger T, Bernabeu MO. Association between erythrocyte dynamics and vessel remodelling in developmental vascular networks. J R Soc Interface 2021; 18:20210113. [PMID: 34157895 PMCID: PMC8220266 DOI: 10.1098/rsif.2021.0113] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 06/01/2021] [Indexed: 12/14/2022] Open
Abstract
Sprouting angiogenesis is an essential vascularization mechanism consisting of sprouting and remodelling. The remodelling phase is driven by rearrangements of endothelial cells (ECs) within the post-sprouting vascular plexus. Prior work has uncovered how ECs polarize and migrate in response to flow-induced wall shear stress (WSS). However, the question of how the presence of erythrocytes (widely known as red blood cells (RBCs)) and their impact on haemodynamics affect vascular remodelling remains unanswered. Here, we devise a computational framework to model cellular blood flow in developmental mouse retina. We demonstrate a previously unreported highly heterogeneous distribution of RBCs in primitive vasculature. Furthermore, we report a strong association between vessel regression and RBC hypoperfusion, and identify plasma skimming as the driving mechanism. Live imaging in a developmental zebrafish model confirms this association. Taken together, our results indicate that RBC dynamics are fundamental to establishing the regional WSS differences driving vascular remodelling via their ability to modulate effective viscosity.
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Affiliation(s)
- Qi Zhou
- School of Engineering, Institute for Multiscale Thermofluids, The University of Edinburgh, Edinburgh, UK
| | - Tijana Perovic
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | - Ines Fechner
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | - Lowell T. Edgar
- Centre for Medical Informatics, Usher Institute, The University of Edinburgh, Edinburgh, UK
| | - Peter R. Hoskins
- Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, UK
- Biomedical Engineering, University of Dundee, Dundee, UK
| | - Holger Gerhardt
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
- Vascular Patterning Laboratory, Department of Oncology and Leuven Cancer Institute (LKI), KU Leuven, Belgium
- DZHK (German Center for Cardiovascular Research), Germany
- Berlin Institute of Health, Germany
| | - Timm Krüger
- School of Engineering, Institute for Multiscale Thermofluids, The University of Edinburgh, Edinburgh, UK
| | - Miguel O. Bernabeu
- Centre for Medical Informatics, Usher Institute, The University of Edinburgh, Edinburgh, UK
- The Bayes Centre, The University of Edinburgh, Edinburgh, UK
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17
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Pskowski A, Bagchi P, Zahn JD. Investigation of red blood cell partitioning in an in vitro microvascular bifurcation. Artif Organs 2021; 45:1083-1096. [PMID: 33590890 DOI: 10.1111/aor.13941] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 01/29/2021] [Accepted: 02/09/2021] [Indexed: 01/12/2023]
Abstract
There is a long history of research examining red blood cell (RBC) partitioning in microvasculature bifurcations. These studies commonly report results describing partitioning that exists as either regular partitioning, which occurs when the RBC flux ratio is greater than the bulk fluid flowrate ratio, or reverse partitioning when the RBC flux ratio is less than or equal to that of the bulk fluid flowrate. This paper presents a study of RBC partitioning in a single bifurcating microchannel with dimensions of 6 to 16 μm, investigating the effects of hematocrit, channel width, daughter channel flowrate ratio, and bifurcation angle. The erythrocyte flux ratio, N*, manifests itself as either regular or reverse partitioning, and time-dependent partitioning is much more dynamic, occurring as both regular and reverse partitioning. We report a significant reduction in the well-known sigmoidal variation of the erythrocyte flux ratio (N*) versus the volumetric flowrate ratio (Q*), partitioning behavior with increasing hematocrit in microchannels when the channel dimensions are comparable with cell size. RBCs "lingering" or jamming at the bifurcation were also observed and quantified in vitro. Results from trajectory analyses suggest that the RBC position in the feeder channel strongly affects both partitioning and lingering frequency of RBCs, with both being significantly reduced when RBCs flow on streamlines near the edge of the channel as opposed to the center of the channel. Furthermore, our experiments suggest that even at low Reynolds number, partitioning is affected by the bifurcation angle by increasing cell-cell interactions. The presented results provide further insight into RBC partitioning as well as perfusion throughout the microvasculature.
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Affiliation(s)
- Andrew Pskowski
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Prosenjit Bagchi
- Department of Mechanical and Aerospace Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Jeffrey D Zahn
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
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18
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Zhou Q, Fidalgo J, Bernabeu MO, Oliveira MSN, Krüger T. Emergent cell-free layer asymmetry and biased haematocrit partition in a biomimetic vascular network of successive bifurcations. SOFT MATTER 2021; 17:3619-3633. [PMID: 33459318 DOI: 10.1039/d0sm01845g] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Blood is a vital soft matter, and its normal circulation in the human body relies on the distribution of red blood cells (RBCs) at successive bifurcations. Understanding how RBCs are partitioned at bifurcations is key for the optimisation of microfluidic devices as well as for devising novel strategies for diagnosis and treatment of blood-related diseases. We report the dynamics of RBC suspensions flowing through a biomimetic vascular network incorporating three generations of microchannels and two classical types of bifurcations at the arteriole level. Our microfluidic experiments with dilute and semidilute RBC suspensions demonstrate the emergence of excessive heterogeneity of RBC concentration in downstream generations upon altering the network's outflow rates. Through parallel simulations using the immersed-boundary-lattice-Boltzmann method, we reveal that the heterogeneity is attributed to upstream perturbations in the cell-free layer (CFL) and lack of its recovery between consecutive bifurcations owing to suppressed hydrodynamic lift under reduced flow conditions. In the dilute/semidilute regime, this perturbation dominates over the effect of local fractional flow at the bifurcation and can lead to inherently unfavourable child branches that are deprived of RBCs even for equal flow split. Our work highlights the importance of CFL asymmetry cascading down a vascular network, which leads to biased phase separation that deviates from established empirical predictions.
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Affiliation(s)
- Qi Zhou
- School of Engineering, Institute for Multiscale Thermofluids, University of Edinburgh, Edinburgh EH9 3FB, UK.
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19
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Giannokostas K, Dimakopoulos Y, Anayiotos A, Tsamopoulos J. Advanced Constitutive Modeling of the Thixotropic Elasto-Visco-Plastic Behavior of Blood: Steady-State Blood Flow in Microtubes. MATERIALS (BASEL, SWITZERLAND) 2021; 14:E367. [PMID: 33451107 PMCID: PMC7828603 DOI: 10.3390/ma14020367] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 01/02/2021] [Accepted: 01/09/2021] [Indexed: 12/15/2022]
Abstract
The present work focuses on the in-silico investigation of the steady-state blood flow in straight microtubes, incorporating advanced constitutive modeling for human blood and blood plasma. The blood constitutive model accounts for the interplay between thixotropy and elasto-visco-plasticity via a scalar variable that describes the level of the local blood structure at any instance. The constitutive model is enhanced by the non-Newtonian modeling of the plasma phase, which features bulk viscoelasticity. Incorporating microcirculation phenomena such as the cell-free layer (CFL) formation or the Fåhraeus and the Fåhraeus-Lindqvist effects is an indispensable part of the blood flow investigation. The coupling between them and the momentum balance is achieved through correlations based on experimental observations. Notably, we propose a new simplified form for the dependence of the apparent viscosity on the hematocrit that predicts the CFL thickness correctly. Our investigation focuses on the impact of the microtube diameter and the pressure-gradient on velocity profiles, normal and shear viscoelastic stresses, and thixotropic properties. We demonstrate the microstructural configuration of blood in steady-state conditions, revealing that blood is highly aggregated in narrow tubes, promoting a flat velocity profile. Additionally, the proper accounting of the CFL thickness shows that for narrow microtubes, the reduction of discharged hematocrit is significant, which in some cases is up to 70%. At high pressure-gradients, the plasmatic proteins in both regions are extended in the flow direction, developing large axial normal stresses, which are more significant in the core region. We also provide normal stress predictions at both the blood/plasma interface (INS) and the tube wall (WNS), which are difficult to measure experimentally. Both decrease with the tube radius; however, they exhibit significant differences in magnitude and type of variation. INS varies linearly from 4.5 to 2 Pa, while WNS exhibits an exponential decrease taking values from 50 mPa to zero.
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Affiliation(s)
- Konstantinos Giannokostas
- Laboratory of Fluid Mechanics and Rheology, Department of Chemical Engineering, University of Patras, 26504 Patras, Greece; (K.G.); (J.T.)
| | - Yannis Dimakopoulos
- Laboratory of Fluid Mechanics and Rheology, Department of Chemical Engineering, University of Patras, 26504 Patras, Greece; (K.G.); (J.T.)
| | - Andreas Anayiotos
- Department of Mechanical and Materials Engineering, Cyprus University of Technology, Limassol 3036, Cyprus;
| | - John Tsamopoulos
- Laboratory of Fluid Mechanics and Rheology, Department of Chemical Engineering, University of Patras, 26504 Patras, Greece; (K.G.); (J.T.)
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20
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Bonfanti M, Franzetti G, Homer-Vanniasinkam S, Díaz-Zuccarini V, Balabani S. A Combined In Vivo, In Vitro, In Silico Approach for Patient-Specific Haemodynamic Studies of Aortic Dissection. Ann Biomed Eng 2020; 48:2950-2964. [PMID: 32929558 PMCID: PMC7723947 DOI: 10.1007/s10439-020-02603-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 09/02/2020] [Indexed: 12/30/2022]
Abstract
The optimal treatment of Type-B aortic dissection (AD) is still a subject of debate, with up to 50% of the cases developing late-term complications requiring invasive intervention. A better understanding of the patient-specific haemodynamic features of AD can provide useful insights on disease progression and support clinical management. In this work, a novel in vitro and in silico framework to perform personalised studies of AD, informed by non-invasive clinical data, is presented. A Type-B AD was investigated in silico using computational fluid dynamics (CFD) and in vitro by means of a state-of-the-art mock circulatory loop and particle image velocimetry (PIV). Both models not only reproduced the anatomical features of the patient, but also imposed physiologically-accurate and personalised boundary conditions. Experimental flow rate and pressure waveforms, as well as detailed velocity fields acquired via PIV, are extensively compared against numerical predictions at different locations in the aorta, showing excellent agreement. This work demonstrates how experimental and numerical tools can be developed in synergy to accurately reproduce patient-specific AD blood flow. The combined platform presented herein constitutes a powerful tool for advanced haemodynamic studies for a range of vascular conditions, allowing not only the validation of CFD models, but also clinical decision support, surgical planning as well as medical device innovation.
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Affiliation(s)
- Mirko Bonfanti
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS), Department of Medical Physics and Biomedical Engineering, University College London, 43-45 Foley Street, London, W1W 7TS UK
| | - Gaia Franzetti
- Department of Mechanical Engineering, University College London, Torrington Place, London, WC1E 7JE UK
| | - Shervanthi Homer-Vanniasinkam
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS), Department of Medical Physics and Biomedical Engineering, University College London, 43-45 Foley Street, London, W1W 7TS UK
- Department of Mechanical Engineering, University College London, Torrington Place, London, WC1E 7JE UK
- Leeds Teaching Hospitals NHS Trust, Great George Street, Leeds, LS1 3EX UK
| | - Vanessa Díaz-Zuccarini
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS), Department of Medical Physics and Biomedical Engineering, University College London, 43-45 Foley Street, London, W1W 7TS UK
- Department of Mechanical Engineering, University College London, Torrington Place, London, WC1E 7JE UK
| | - Stavroula Balabani
- Department of Mechanical Engineering, University College London, Torrington Place, London, WC1E 7JE UK
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21
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Assessment of Fibrinogen Macromolecules Interaction with Red Blood Cells Membrane by Means of Laser Aggregometry, Flow Cytometry, and Optical Tweezers Combined with Microfluidics. Biomolecules 2020; 10:biom10101448. [PMID: 33076409 PMCID: PMC7602533 DOI: 10.3390/biom10101448] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Revised: 10/07/2020] [Accepted: 10/12/2020] [Indexed: 12/17/2022] Open
Abstract
An elevated concentration of fibrinogen in blood is a significant risk factor during many pathological diseases, as it leads to an increase in red blood cells (RBC) aggregation, resulting in hemorheological disorders. Despite the biomedical importance, the mechanisms of fibrinogen-induced RBC aggregation are still debatable. One of the discussed models is the non-specific adsorption of fibrinogen macromolecules onto the RBC membrane, leading to the cells bridging in aggregates. However, recent works point to the specific character of the interaction between fibrinogen and the RBC membrane. Fibrinogen is the major physiological ligand of glycoproteins receptors IIbIIIa (GPIIbIIIa or αIIββ3 or CD41/CD61). Inhibitors of GPIIbIIIa are widely used in clinics for the treatment of various cardiovascular diseases as antiplatelets agents preventing the platelets’ aggregation. However, the effects of GPIIbIIIa inhibition on RBC aggregation are not sufficiently well studied. The objective of the present work was the complex multimodal in vitro study of the interaction between fibrinogen and the RBC membrane, revealing the role of GPIIbIIIa in the specificity of binding of fibrinogen by the RBC membrane and its involvement in the cells’ aggregation process. We demonstrate that GPIIbIIIa inhibition leads to a significant decrease in the adsorption of fibrinogen macromolecules onto the membrane, resulting in the reduction of RBC aggregation. We show that the mechanisms underlying these effects are governed by a decrease in the bridging components of RBC aggregation forces.
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22
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Mantegazza A, Ungari M, Clavica F, Obrist D. Local vs. Global Blood Flow Modulation in Artificial Microvascular Networks: Effects on Red Blood Cell Distribution and Partitioning. Front Physiol 2020; 11:566273. [PMID: 33123027 PMCID: PMC7571285 DOI: 10.3389/fphys.2020.566273] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 08/12/2020] [Indexed: 12/12/2022] Open
Abstract
Our understanding of cerebral blood flow (CBF) regulation during functional activation is still limited. Alongside with the accepted role of smooth muscle cells in controlling the arteriolar diameter, a new hypothesis has been recently formulated suggesting that CBF may be modulated by capillary diameter changes mediated by pericytes. In this study, we developed in vitro microvascular network models featuring a valve enabling the dilation of a specific micro-channel. This allowed us to investigate the non-uniform red blood cell (RBC) partitioning at microvascular bifurcations (phase separation) and the hematocrit distribution at rest and for two scenarios modeling capillary and arteriolar dilation. RBC partitioning showed similar phase separation behavior during baseline and activation. Results indicated that the RBCs at diverging bifurcations generally enter the high-flow branch (classical partitioning). Inverse behavior (reverse partitioning) was observed for skewed hematocrit profiles in the parent vessel of bifurcations, especially for high RBC velocity (i.e., arteriolar activation). Moreover, results revealed that a local capillary dilation, as it may be mediated in vivo by pericytes, led to a localized increase of RBC flow and a heterogeneous hematocrit redistribution within the whole network. In case of a global increase of the blood flow, as it may be achieved by dilating an arteriole, a homogeneous increase of RBC flow was observed in the whole network and the RBCs were concentrated along preferential pathways. In conclusion, overall increase of RBC flow could be obtained by arteriolar and capillary dilation, but only capillary dilation was found to alter the perfusion locally and heterogeneously.
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Affiliation(s)
- Alberto Mantegazza
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Matteo Ungari
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Francesco Clavica
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland.,Integrated Actuators Laboratory, École Polytechnique Fédérale de Lausanne, Neuchâtel, Switzerland
| | - Dominik Obrist
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
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23
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Zhou Q, Fidalgo J, Calvi L, Bernabeu MO, Hoskins PR, Oliveira MSN, Krüger T. Spatiotemporal Dynamics of Dilute Red Blood Cell Suspensions in Low-Inertia Microchannel Flow. Biophys J 2020; 118:2561-2573. [PMID: 32325022 DOI: 10.1016/j.bpj.2020.03.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 03/01/2020] [Accepted: 03/17/2020] [Indexed: 11/27/2022] Open
Abstract
Microfluidic technologies are commonly used for the manipulation of red blood cell (RBC) suspensions and analyses of flow-mediated biomechanics. To enhance the performance of microfluidic devices, understanding the dynamics of the suspensions processed within is crucial. We report novel, to our knowledge, aspects of the spatiotemporal dynamics of RBC suspensions flowing through a typical microchannel at low Reynolds number. Through experiments with dilute RBC suspensions, we find an off-center two-peak (OCTP) profile of cells contrary to the centralized distribution commonly reported for low-inertia flows. This is reminiscent of the well-known "tubular pinch effect," which arises from inertial effects. However, given the conditions of negligible inertia in our experiments, an alternative explanation is needed for this OCTP profile. Our massively parallel simulations of RBC flow in real-size microfluidic dimensions using the immersed-boundary-lattice-Boltzmann method confirm the experimental findings and elucidate the underlying mechanism for the counterintuitive RBC pattern. By analyzing the RBC migration and cell-free layer development within a high-aspect-ratio channel, we show that such a distribution is co-determined by the spatial decay of hydrodynamic lift and the global deficiency of cell dispersion in dilute suspensions. We find a cell-free layer development length greater than 46 and 28 hydraulic diameters in the experiment and simulation, respectively, exceeding typical lengths of microfluidic designs. Our work highlights the key role of transient cell distribution in dilute suspensions, which may negatively affect the reliability of experimental results if not taken into account.
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Affiliation(s)
- Qi Zhou
- School of Engineering, Institute for Multiscale Thermofluids, University of Edinburgh, Edinburgh, United Kingdom
| | - Joana Fidalgo
- James Weir Fluids Laboratory, Department of Mechanical and Aerospace Engineering, University of Strathclyde, Glasgow, United Kingdom
| | - Lavinia Calvi
- School of Engineering, Institute for Multiscale Thermofluids, University of Edinburgh, Edinburgh, United Kingdom
| | - Miguel O Bernabeu
- Centre for Medical Informatics, Usher Institute, Edinburgh, United Kingdom
| | - Peter R Hoskins
- Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, United Kingdom
| | - Mónica S N Oliveira
- James Weir Fluids Laboratory, Department of Mechanical and Aerospace Engineering, University of Strathclyde, Glasgow, United Kingdom.
| | - Timm Krüger
- School of Engineering, Institute for Multiscale Thermofluids, University of Edinburgh, Edinburgh, United Kingdom.
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Mantegazza A, Clavica F, Obrist D. In vitro investigations of red blood cell phase separation in a complex microchannel network. BIOMICROFLUIDICS 2020; 14:014101. [PMID: 31933711 PMCID: PMC6941945 DOI: 10.1063/1.5127840] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 12/14/2019] [Indexed: 06/10/2023]
Abstract
Microvascular networks feature a complex topology with multiple bifurcating vessels. Nonuniform partitioning (phase separation) of red blood cells (RBCs) occurs at diverging bifurcations, leading to a heterogeneous RBC distribution that ultimately affects the oxygen delivery to living tissues. Our understanding of the mechanisms governing RBC heterogeneity is still limited, especially in large networks where the RBC dynamics can be nonintuitive. In this study, our quantitative data for phase separation were obtained in a complex in vitro network with symmetric bifurcations and 176 microchannels. Our experiments showed that the hematocrit is heterogeneously distributed and confirmed the classical result that the branch with a higher blood fraction received an even higher RBC fraction (classical partitioning). An inversion of this classical phase separation (reverse partitioning) was observed in the case of a skewed hematocrit profile in the parent vessels of bifurcations. In agreement with a recent computational study [P. Balogh and P. Bagchi, Phys. Fluids 30,051902 (2018)], a correlation between the RBC reverse partitioning and the skewness of the hematocrit profile due to sequential converging and diverging bifurcations was reported. A flow threshold below which no RBCs enter a branch was identified. These results highlight the importance of considering the RBC flow history and the local RBC distribution to correctly describe the RBC phase separation in complex networks.
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Affiliation(s)
- A Mantegazza
- ARTORG Center for Biomedical Engineering Research, University of Bern, 3010 Bern, Switzerland
| | | | - D Obrist
- ARTORG Center for Biomedical Engineering Research, University of Bern, 3010 Bern, Switzerland
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25
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Gómez Bardón R, Passos A, Piergiovanni M, Balabani S, Pennati G, Dubini G. Haematocrit heterogeneity in blood flows past microfluidic models of oxygenating fibre bundles. Med Eng Phys 2019; 73:30-38. [DOI: 10.1016/j.medengphy.2019.07.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 06/11/2019] [Accepted: 07/19/2019] [Indexed: 10/26/2022]
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26
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Study of the Partitioning of Red Blood Cells Through Asymmetric Bifurcating Microchannels. J Med Biol Eng 2019. [DOI: 10.1007/s40846-019-00492-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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27
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Shear-Induced Encapsulation into Red Blood Cells: A New Microfluidic Approach to Drug Delivery. Ann Biomed Eng 2019; 48:236-246. [DOI: 10.1007/s10439-019-02342-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Accepted: 08/09/2019] [Indexed: 01/18/2023]
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28
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Hymel SJ, Lan H, Fujioka H, Khismatullin DB. Cell trapping in Y-junction microchannels: A numerical study of the bifurcation angle effect in inertial microfluidics. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2019; 31:082003. [PMID: 31406457 PMCID: PMC6688893 DOI: 10.1063/1.5113516] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 07/09/2019] [Indexed: 05/31/2023]
Abstract
The majority of microfluidic technologies for cell sorting and isolation involve bifurcating (e.g., Y- or T-shaped junction) microchannels to trap the cells of a specific type. However, the microfluidic trapping efficiency remains low, independently of whether the cells are separated by a passive or an active sorting method. Using a custom computational algorithm, we studied the migration of separated deformable cells in a Y-junction microchannel, with a bifurcation angle ranging from 30° to 180°. Single or two cells of initially spherical shape were considered under flow conditions corresponding to inertial microfluidics. Through the numerical simulation, we identified the effects of cell size, cytoplasmic viscoelasticity, cortical tension, flow rate, and bifurcation angle on the critical separation distance for cell trapping. The results of this study show that the trapping and isolation of blood cells, and circulating tumor cells in a Y-junction microchannel was most efficient and least dependent on the flow rate at the bifurcation angle of 120°. At this angle, the trapping efficiency for white blood cells and circulating tumor cells increased, respectively, by 46% and 43%, in comparison with the trapping efficiency at 60°. The efficiency to isolate invasive tumor cells from noninvasive ones increased by 32%. This numerical study provides important design criteria to optimize microfluidic technology for deformability-based cell sorting and isolation.
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Affiliation(s)
| | - Hongzhi Lan
- Department of Pediatrics, Stanford University, Stanford, California 94305, USA
| | - Hideki Fujioka
- Center for Computational Science, Tulane University, New Orleans, Louisiana 70118, USA
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29
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Xiao LL, Lin CS, Chen S, Liu Y, Fu BM, Yan WW. Effects of red blood cell aggregation on the blood flow in a symmetrical stenosed microvessel. Biomech Model Mechanobiol 2019; 19:159-171. [PMID: 31297646 DOI: 10.1007/s10237-019-01202-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2018] [Accepted: 07/06/2019] [Indexed: 11/25/2022]
Abstract
In order to figure out whether red blood cell (RBC) aggregation is beneficial or deleterious for the blood flow through a stenosis, fluid mechanics of a microvascular stenosis was examined through simulating the dynamics of deformable red blood cells suspended in plasma using dissipative particle dynamics. The spatial variation in time-averaged cell-free layer (CFL) thickness and velocity profiles indicated that the blood flow exhibits asymmetry along the flow direction. The RBC accumulation occurs upstream the stenosis, leading to a thinner CFL and reduced flow velocity. Therefore, the emergence of stenosis produces an increased blood flow resistance. In addition, an enhanced Fahraeus-Lindqvist effect was observed in the presence of the stenosis. Finally, the effect of RBC aggregation combined with decreased stenosis on the blood flow was investigated. The findings showed that when the RBC clusters pass through the stenosis with a throat comparable to the RBC core in diameter, the blood flow resistance decreases with increasing intercellular interaction strength. But if the RBC core is larger and even several times than the throat, the blood flow resistance increases largely under strong RBC aggregation, which may contribute to the mechanism of the microthrombus formation.
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Affiliation(s)
- L L Xiao
- School of Mechanical and Automotive Engineering, Shanghai University of Engineering Science, Shanghai, China.
| | - C S Lin
- School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai, China
| | - S Chen
- School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai, China
| | - Y Liu
- Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hong Kong, China
| | - B M Fu
- Department of Biomedical Engineering, The City College of the City University of New York, New York, NY, USA
| | - W W Yan
- College of Metrology and Measurement Engineering, China Jiliang University, Hangzhou, China
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30
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Balogh P, Bagchi P. Three-dimensional distribution of wall shear stress and its gradient in red cell-resolved computational modeling of blood flow in in vivo-like microvascular networks. Physiol Rep 2019; 7:e14067. [PMID: 31062494 PMCID: PMC6503071 DOI: 10.14814/phy2.14067] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 03/20/2019] [Accepted: 03/25/2019] [Indexed: 01/13/2023] Open
Abstract
Using a high-fidelity, 3D computational model of blood flow in microvascular networks, we provide the full 3D distribution of wall shear stress (WSS), and its gradient (WSSG), and quantify the influence of red blood cells (RBCs) on WSS and WSSG. The deformation and flow dynamics of the individual RBCs are accurately resolved in the model, while physiologically realistic microvascular networks comprised of multiple bifurcations, convergences, and tortuous vessels are considered. A strong heterogeneity in WSS and WSSG is predicted across the networks, with the highest WSS occurring in precapillary bifurcations and capillary vessels. 3D variations of WSS and WSSG are shown to occur due to both network morphology and the influence of RBCs. The RBCs increase the WSS by as much as three times compared to that when no RBCs are present, and the highest increase is observed in venules. WSSG also increases significantly, and high WSSGs occur over wider regions in the presence of RBCs. In most vessels, the circumferential component of WSSG is observed to be greater than the axial component in the presence of RBCs, while the opposite trend is observed when RBCs are not considered. These results underscore the important role of RBCs on WSS and WSSG that cannot be predicted by widely used 1D models of network blood flow. Furthermore, the subendothelium-scale variations of WSS and WSSG predicted by the present model have implications in terms of endothelial cell functions in the microvasculature.
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Affiliation(s)
- Peter Balogh
- Mechanical and Aerospace Engineering DepartmentRutgers, The State University of New JerseyPiscatawayNew Jersey
| | - Prosenjit Bagchi
- Mechanical and Aerospace Engineering DepartmentRutgers, The State University of New JerseyPiscatawayNew Jersey
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31
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König CS, Balabani S, Hackett GI, Strange RC, Ramachandran S. Testosterone Therapy: An Assessment of the Clinical Consequences of Changes in Hematocrit and Blood Flow Characteristics. Sex Med Rev 2019; 7:650-660. [PMID: 30926458 DOI: 10.1016/j.sxmr.2019.01.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 01/19/2019] [Accepted: 01/23/2019] [Indexed: 10/27/2022]
Abstract
INTRODUCTION Clinical guidelines indicate that hematocrit should be monitored during testosterone replacement therapy (TTh), with action taken if a level of 0.54 is exceeded. AIM To consider the extent of changes in hematocrit and putative effects on viscosity, blood flow, and mortality rates after TTh. METHODS We focused on literature describing benefits and possible pitfalls of TTh, including increased hematocrit. We used data from the BLAST RCT to determine change in hematocrit after 30 weeks of TTh and describe a clinical case showing the need for monitoring. We consider the validity of the current hematocrit cutoff value at which TTh may be modified. Ways in which hematocrit alters blood flow in the micro- and macro-vasculature are also considered. MAIN OUTCOME MEASURES The following measures were assessed: (i) change in hematocrit, (ii) corresponding actions taken in clinical practice, and (iii) possible blood flow changes following change in hematocrit. RESULTS Analysis of data from the BLAST RCT showed a significant increase in mean hematocrit of 0.01, the increase greater in men with lower baseline values. Although 0 of 61 men given TTh breached the suggested cutoff of 0.54 after 30 weeks, a clinical case demonstrates the need to monitor hematocrit. An association between hematocrit and morbidity and mortality appears likely but not proven and may be evident only in patient subgroups. The consequences of an increased hematocrit may be mediated by alterations in blood viscosity, oxygen delivery, and flow. Their relative impact may vary in different vascular beds. CONCLUSIONS TTh can effect an increased hematocrit via poorly understood mechanisms and may have harmful effects on blood flow that differ in patient subgroups. At present, there appears no scientific basis for using a hematocrit of 0.54 to modify TTh; other values may be more appropriate in particular patient groups. König CS, Balabani S, Hackett GI, et al. Testosterone Therapy: An Assessment of the Clinical Consequences of Changes in Hematocrit and Blood Flow Characteristics. Sex Med Rev 2019;7:650-660.
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Affiliation(s)
- Carola S König
- College of Engineering, Design & Physical Sciences, Brunel University, London, England, United Kingdom
| | - Stavroula Balabani
- Faculty of Engineering Sciences, University College London, London, United Kingdom
| | - Geoffrey I Hackett
- Department of Urology, University Hospitals Birmingham NHS Foundation Trust, West Midlands, England, United Kingdom
| | - Richard C Strange
- Institute for Science and Technology in Medicine, Keele University, Staffordshire, England, United Kingdom
| | - Sudarshan Ramachandran
- College of Engineering, Design & Physical Sciences, Brunel University, London, England, United Kingdom; Department of Clinical Biochemistry, University Hospitals Birmingham NHS Foundation Trust, West Midlands, England, United Kingdom; Department of Clinical Biochemistry, University Hospitals of North Midlands / Faculty of Health Sciences, Staffordshire University, Staffordshire, England, United Kingdom.
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32
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Reinhart WH, Piety NZ, Shevkoplyas SS. Influence of feeding hematocrit and perfusion pressure on hematocrit reduction (Fåhraeus effect) in an artificial microvascular network. Microcirculation 2018; 24. [PMID: 28801994 DOI: 10.1111/micc.12396] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 08/08/2017] [Indexed: 12/27/2022]
Abstract
OBJECTIVE Hct in narrow vessels is reduced due to concentration of fast-flowing RBCs in the center, and of slower flowing plasma along the wall of the vessel, which in combination with plasma skimming at bifurcations leads to the striking heterogeneity of local Hct in branching capillary networks known as the network Fåhraeus effect. We analyzed the influence of feeding Hct and perfusion pressure on the Fåhraeus effect in an AMVN. METHODS RBC suspensions in plasma with Hcts between 20% and 70% were perfused at pressures of 5-60 cm H2 O through the AMVN. A microscope and high-speed camera were used to measure RBC velocity and Hct in microchannels of height of 5 μm and widths of 5-19 μm. RESULTS Channel Hcts were reduced compared with Hctfeeding in 5 and 7 μm microchannels, but not in larger microchannels. The magnitude of Hct reduction increased with decreasing Hctfeeding and decreasing ΔP (flow velocity), showing an about sevenfold higher effect for 40% Hctfeeding and low pressure/flow velocity than for 60% Hctfeeding and high pressure/flow velocity. CONCLUSIONS The magnitude of the network Fåhraeus effect in an AMVN is inversely related to Hctfeeding and ΔP.
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Affiliation(s)
| | - Nathaniel Z Piety
- Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, TX, USA
| | - Sergey S Shevkoplyas
- Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, TX, USA
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33
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Chuang CH, Kikuchi K, Ueno H, Numayama-Tsuruta K, Yamaguchi T, Ishikawa T. Collective spreading of red blood cells flowing in a microchannel. J Biomech 2018; 69:64-69. [PMID: 29397999 DOI: 10.1016/j.jbiomech.2018.01.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 12/19/2017] [Accepted: 01/08/2018] [Indexed: 11/27/2022]
Abstract
Due to recent advances in micro total analysis system technologies, microfluidics provides increased opportunities to manipulate, stimulate, and diagnose blood cells. Controlling the concentration of cells at a given position across the width of a channel is an important aspect in the design of microfluidic devices. Despite its biomedical importance, the collective spreading of red blood cells (RBCs) in a microchannel has not yet been fully clarified. In this study, we experimentally investigated the collective spreading of RBCs in a straight microchannel, and found that RBCs initially distributed in one side of the microchannel spread to the spanwise direction during downstream flow. Spreading increased considerably as the hematocrit increased, though the flow rate had a small effect. We proposed a scaling argument to show that this spreading phenomenon was diffusive and mainly induced by cell-cell interactions. The dispersion coefficient was approximately proportional to the flow rate and the hematocrit. These results are useful in understanding collective behaviors of RBCs in a microchannel and in microcirculation.
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Affiliation(s)
- Cheng-Hsi Chuang
- Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan
| | - Kenji Kikuchi
- Dept. Finemechanics, Graduate School of Engineering, Tohoku University, Sendai, Japan
| | - Hironori Ueno
- Dept. Molecular Function and Life Science, Aichi University of Education, Kariya, Japan
| | | | - Takami Yamaguchi
- Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan
| | - Takuji Ishikawa
- Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan; Dept. Finemechanics, Graduate School of Engineering, Tohoku University, Sendai, Japan.
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34
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Direct Numerical Simulation of Cellular-Scale Blood Flow in 3D Microvascular Networks. Biophys J 2018; 113:2815-2826. [PMID: 29262374 DOI: 10.1016/j.bpj.2017.10.020] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Revised: 08/16/2017] [Accepted: 10/11/2017] [Indexed: 12/16/2022] Open
Abstract
We present, to our knowledge, the first direct numerical simulation of 3D cellular-scale blood flow in physiologically realistic microvascular networks. The vascular networks are designed following in vivo images and data, and are comprised of bifurcating, merging, and winding vessels. Our model resolves the large deformation and dynamics of each individual red blood cell flowing through the networks with high fidelity, while simultaneously retaining the highly complex geometric details of the vascular architecture. To our knowledge, our simulations predict several novel and unexpected phenomena. We show that heterogeneity in hemodynamic quantities, which is a hallmark of microvascular blood flow, appears both in space and time, and that the temporal heterogeneity is more severe than its spatial counterpart. The cells are observed to frequently jam at vascular bifurcations resulting in reductions in hematocrit and flow rate in the daughter and mother vessels. We find that red blood cell jamming at vascular bifurcations results in several orders-of-magnitude increase in hemodynamic resistance, and thus provides an additional mechanism of increased in vivo blood viscosity as compared to that determined in vitro. A striking result from our simulations is negative pressure-flow correlations observed in several vessels, implying a significant deviation from Poiseuille's law. Furthermore, negative correlations between vascular resistance and hematocrit are observed in various vessels, also defying a major principle of particulate suspension flow. To our knowledge, these novel findings are absent in blood flow in straight tubes, and they underscore the importance of considering realistic physiological geometry and resolved cellular interactions in modeling microvascular hemodynamics.
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35
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Namgung B, Ng YC, Leo HL, Rifkind JM, Kim S. Near-Wall Migration Dynamics of Erythrocytes in Vivo: Effects of Cell Deformability and Arteriolar Bifurcation. Front Physiol 2017; 8:963. [PMID: 29238303 PMCID: PMC5712576 DOI: 10.3389/fphys.2017.00963] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 11/13/2017] [Indexed: 01/12/2023] Open
Abstract
Red blood cell (RBC) deformability has a significant impact on microcirculation by affecting cell dynamics. Despite previous studies that have demonstrated the margination of rigid cells and particles in vitro, little information is available on the in vivo margination of deformability-impaired RBCs under physiological flow and hematocrit conditions. Thus, in this study, we examined how the deformability-dependent, RBC migration alters the cell distribution under physiological conditions, particularly in arteriolar network flows. The hardened RBCs (hRBCs) were found to preferentially flow near the vessel walls of small arterioles (diameter = 47.1-93.3 μm). The majority of the hRBCs (63%) were marginated within the range of 0.7R-0.9R (R: radial position normalized by vessel radius), indicating that the hRBCs preferentially accumulated near the vessel walls. The laterally marginated hRBCs maintained their lateral positions near the walls while traversing downstream with attenuated radial dispersion. In addition, the immediate displacement of RBCs while traversing a bifurcation also contributes to the near-wall accumulation of hRBCs. The notable difference in the inward migration between the marginated nRBCs and hRBCs after bifurcations further supports the potential role of bifurcations in the accumulation of hRBCs near the walls.
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Affiliation(s)
- Bumseok Namgung
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
- Biomedical Institute for Global Health Research and Technology, National University of Singapore, Singapore, Singapore
| | - Yan Cheng Ng
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, Singapore
| | - Hwa Liang Leo
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Joseph M. Rifkind
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins Medicine, Baltimore, MD, United States
| | - Sangho Kim
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
- Biomedical Institute for Global Health Research and Technology, National University of Singapore, Singapore, Singapore
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, Singapore
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36
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Kaliviotis E, Pasias D, Sherwood J, Balabani S. Red blood cell aggregate flux in a bifurcating microchannel. Med Eng Phys 2017; 48:23-30. [DOI: 10.1016/j.medengphy.2017.04.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 03/21/2017] [Accepted: 04/16/2017] [Indexed: 11/26/2022]
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37
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Kaliviotis E, Sherwood JM, Balabani S. Partitioning of red blood cell aggregates in bifurcating microscale flows. Sci Rep 2017; 7:44563. [PMID: 28303921 PMCID: PMC5355999 DOI: 10.1038/srep44563] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 02/09/2017] [Indexed: 12/12/2022] Open
Abstract
Microvascular flows are often considered to be free of red blood cell aggregates, however, recent studies have demonstrated that aggregates are present throughout the microvasculature, affecting cell distribution and blood perfusion. This work reports on the spatial distribution of red blood cell aggregates in a T-shaped bifurcation on the scale of a large microvessel. Non-aggregating and aggregating human red blood cell suspensions were studied for a range of flow splits in the daughter branches of the bifurcation. Aggregate sizes were determined using image processing. The mean aggregate size was marginally increased in the daughter branches for a range of flow rates, mainly due to the lower shear conditions and the close cell and aggregate proximity therein. A counterintuitive decrease in the mean aggregate size was apparent in the lower flow rate branches. This was attributed to the existence of regions depleted by aggregates of certain sizes in the parent branch, and to the change in the exact flow split location in the T-junction with flow ratio. The findings of the present investigation may have significant implications for microvascular flows and may help explain why the effects of physiological RBC aggregation are not deleterious in terms of in vivo vascular resistance.
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Affiliation(s)
- E Kaliviotis
- Dept. of Mechanical Engineering and Materials Science and Engineering, Cyprus University of Technology, Cyprus.,Dept. of Mechanical Engineering, University College London, UK
| | - J M Sherwood
- Dept. of Bioengineering, Imperial College London, UK
| | - S Balabani
- Dept. of Mechanical Engineering, University College London, UK
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38
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Red blood cell phase separation in symmetric and asymmetric microchannel networks: effect of capillary dilation and inflow velocity. Sci Rep 2016; 6:36763. [PMID: 27857165 PMCID: PMC5114676 DOI: 10.1038/srep36763] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 10/20/2016] [Indexed: 12/31/2022] Open
Abstract
The non-uniform partitioning or phase separation of red blood cells (RBCs) at a diverging bifurcation of a microvascular network is responsible for RBC heterogeneity within the network. The mechanisms controlling RBC heterogeneity are not yet fully understood and there is a need to improve the basic understanding of the phase separation phenomenon. In this context, in vitro experiments can fill the gap between existing in vivo and in silico models as they provide better controllability than in vivo experiments without mathematical idealizations or simplifications inherent to in silico models. In this study, we fabricated simple models of symmetric/asymmetric microvascular networks; we provided quantitative data on the RBC velocity, line density and flux in the daughter branches. In general our results confirmed the tendency of RBCs to enter the daughter branch with higher flow rate (Zweifach-Fung effect); in some cases even inversion of the Zweifach-Fung effect was observed. We showed for the first time a reduction of the Zweifach-Fung effect with increasing flow rate. Moreover capillary dilation was shown to cause an increase of RBC line density and RBC residence time within the dilated capillary underlining the possible role of pericytes in regulating the oxygen supply.
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39
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Kaliviotis E, Dusting J, Sherwood JM, Balabani S. Quantifying local characteristics of velocity, aggregation and hematocrit of human erythrocytes in a microchannel flow. Clin Hemorheol Microcirc 2016; 63:123-48. [DOI: 10.3233/ch-151980] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Efstathios Kaliviotis
- Department of Mechanical Engineering and Materials Science and Engineering, Cyprus University of Technology, Limassol, Cyprus
- Department of Mechanical Engineering, University College London, UK
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40
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Ng YC, Namgung B, Tien SL, Leo HL, Kim S. Symmetry recovery of cell-free layer after bifurcations of small arterioles in reduced flow conditions: effect of RBC aggregation. Am J Physiol Heart Circ Physiol 2016; 311:H487-97. [PMID: 27233764 DOI: 10.1152/ajpheart.00223.2016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 05/26/2016] [Indexed: 11/22/2022]
Abstract
Heterogeneous distribution of red blood cells (RBCs) in downstream vessels of arteriolar bifurcations can be promoted by an asymmetric formation of cell-free layer (CFL) in upstream vessels. Consequently, the CFL widths in subsequent downstream vessels become an important determinant for tissue oxygenation (O2) and vascular tone change by varying nitric oxide (NO) availability. To extend our previous understanding on the formation of CFL in arteriolar bifurcations, this study investigated the formation of CFL widths from 2 to 6 vessel-diameter (2D-6D) downstream of arteriolar bifurcations in the rat cremaster muscle (D = 51.5 ± 1.3 μm). As the CFL widths are highly influenced by RBC aggregation, the degree of aggregation was adjusted to simulate levels seen during physiological and pathological states. Our in vivo experimental results showed that the asymmetry of CFL widths persists along downstream vessels up to 6D from the bifurcating point. Moreover, elevated levels of RBC aggregation appeared to retard the recovery of CFL width symmetry. The required length of complete symmetry recovery was estimated to be greater than 11D under reduced flow conditions, which is relatively longer than interbifurcation distances of arterioles for vessel diameter of ∼50 μm. In addition, our numerical prediction showed that the persistent asymmetry of CFL widths could potentially result in a heterogeneous vasoactivity over the entire arteriolar network in such abnormal flow conditions.
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Affiliation(s)
- Yan Cheng Ng
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore; Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Bumseok Namgung
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Sim Leng Tien
- Department of Hematology, Singapore General Hospital, Singapore; and
| | - Hwa Liang Leo
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore; Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Sangho Kim
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore; Department of Biomedical Engineering, National University of Singapore, Singapore; Department of Surgery, National University of Singapore, Singapore
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41
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Roman S, Merlo A, Duru P, Risso F, Lorthois S. Going beyond 20 μm-sized channels for studying red blood cell phase separation in microfluidic bifurcations. BIOMICROFLUIDICS 2016; 10:034103. [PMID: 27190568 PMCID: PMC4866949 DOI: 10.1063/1.4948955] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 04/27/2016] [Indexed: 05/13/2023]
Abstract
Despite the development of microfluidics, experimental challenges are considerable for achieving a quantitative study of phase separation, i.e., the non-proportional distribution of Red Blood Cells (RBCs) and suspending fluid, in microfluidic bifurcations with channels smaller than 20 μm. Yet, a basic understanding of phase separation in such small vessels is needed for understanding the coupling between microvascular network architecture and dynamics at larger scale. Here, we present the experimental methodologies and measurement techniques developed for that purpose for RBC concentrations (tube hematocrits) ranging between 2% and 20%. The maximal RBC velocity profile is directly measured by a temporal cross-correlation technique which enables to capture the RBC slip velocity at walls with high resolution, highlighting two different regimes (flat and more blunted ones) as a function of RBC confinement. The tube hematocrit is independently measured by a photometric technique. The RBC and suspending fluid flow rates are then deduced assuming the velocity profile of a Newtonian fluid with no slip at walls for the latter. The accuracy of this combination of techniques is demonstrated by comparison with reference measurements and verification of RBC and suspending fluid mass conservation at individual bifurcations. The present methodologies are much more accurate, with less than 15% relative errors, than the ones used in previous in vivo experiments. Their potential for studying steady state phase separation is demonstrated, highlighting an unexpected decrease of phase separation with increasing hematocrit in symmetrical, but not asymmetrical, bifurcations and providing new reference data in regimes where in vitro results were previously lacking.
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Ye SS, Ju M, Kim S. Recovery of cell-free layer and wall shear stress profile symmetry downstream of an arteriolar bifurcation. Microvasc Res 2016; 106:14-23. [PMID: 26969106 DOI: 10.1016/j.mvr.2016.03.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 02/23/2016] [Accepted: 03/07/2016] [Indexed: 11/29/2022]
Abstract
Unequal RBC partitioning at arteriolar bifurcations contributes to dissimilar flow developments between daughter vessels in a bifurcation. Due to the importance of the cell-free layer (CFL) and the wall shear stress (WSS) to physiological processes such as vasoregulation and gas diffusion, we investigated the effects of a bifurcation disturbance on the development of the CFL width and WSS in bifurcation daughter branches. The analysis was performed on a two-dimensional (2-D) computational model of a transverse arteriole at three different flow rates corresponding to parent branch (PB) pseudoshear rates of 60, 170 and 470s(-1), while maintaining a 2-D hematocrit of about 55% in the PB. Flow symmetry was defined using the statistical similarity of the CFL and WSS distributions between the two walls of the vessel branch. In terms of the flow symmetry recovery, higher flow rates caused larger reductions in the flow symmetry indices in the MB and subsequently required longer vessel lengths for complete recovery. Lower tube hematocrits in the SB led to complete symmetry recovery for all flow rates despite the higher initial asymmetry in the SB than in the MB. Arteriolar bifurcations produce unavoidable local CFL asymmetry and the persistence of the asymmetry downstream may increase effective blood viscosity which is especially significant at higher physiological flow rates.
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Affiliation(s)
- Swe Soe Ye
- Department of Biomedical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575, Singapore
| | - Meongkeun Ju
- Department of Biomedical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575, Singapore
| | - Sangho Kim
- Department of Biomedical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575, Singapore; Department of Surgery, National University of Singapore, 1E Kent Ridge Road, Singapore 119228, Singapore.
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Villa CH, Muzykantov VR, Cines DB. The emerging role for red blood cells in haemostasis: opportunity for intervention. ACTA ACUST UNITED AC 2016. [DOI: 10.1111/voxs.12197] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- C. H. Villa
- Department of Pathology and Laboratory Medicine; The Perelman School of Medicine, University of Pennsylvania; Philadelphia PA USA
| | - V. R. Muzykantov
- Department of Pharmacology and Center for Targeted Therapeutics and Translational Nanomedicine of the Institute for Translational Medicine and Therapeutics; The Perelman School of Medicine; University of Pennsylvania; Philadelphia PA USA
| | - D. B. Cines
- Department of Pathology and Laboratory Medicine; The Perelman School of Medicine, University of Pennsylvania; Philadelphia PA USA
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Agrawal R, Sherwood J, Chhablani J, Ricchariya A, Kim S, Jones PH, Balabani S, Shima D. Red blood cells in retinal vascular disorders. Blood Cells Mol Dis 2016; 56:53-61. [DOI: 10.1016/j.bcmd.2015.10.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 10/26/2015] [Indexed: 02/05/2023]
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Lykov K, Li X, Lei H, Pivkin IV, Karniadakis GE. Inflow/Outflow Boundary Conditions for Particle-Based Blood Flow Simulations: Application to Arterial Bifurcations and Trees. PLoS Comput Biol 2015; 11:e1004410. [PMID: 26317829 PMCID: PMC4552763 DOI: 10.1371/journal.pcbi.1004410] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 06/18/2015] [Indexed: 11/19/2022] Open
Abstract
When blood flows through a bifurcation, red blood cells (RBCs) travel into side branches at different hematocrit levels, and it is even possible that all RBCs enter into one branch only, leading to a complete separation of plasma and RBCs. To quantify this phenomenon via particle-based mesoscopic simulations, we developed a general framework for open boundary conditions in multiphase flows that is effective even for high hematocrit levels. The inflow at the inlet is duplicated from a fully developed flow generated in a pilot simulation with periodic boundary conditions. The outflow is controlled by adaptive forces to maintain the flow rate and velocity gradient at fixed values, while the particles leaving the arteriole at the outlet are removed from the system. Upon validation of this approach, we performed systematic 3D simulations to study plasma skimming in arterioles of diameters 20 to 32 microns. For a flow rate ratio 6:1 at the branches, we observed the “all-or-nothing” phenomenon with plasma only entering the low flow rate branch. We then simulated blood-plasma separation in arteriolar bifurcations with different bifurcation angles and same diameter of the daughter branches. Our simulations predict a significant increase in RBC flux through the main daughter branch as the bifurcation angle is increased. Finally, we demonstrated the effectiveness of the new methodology in simulations of blood flow in vessels with multiple inlets and outlets, constructed using an angiogenesis model. Blood tests, which provide a wealth of information on the state of human health, are often performed on cell-free samples. Therefore, blood-plasma separation needs to be achieved. A simple but effective solution for isolating plasma from blood utilizes capillary bifurcations. In a particle-based simulation study of plasma skimming in capillary bifurcations, the blood flow properties such as velocity and pressure fields differ drastically at the inlet and outlet regions. Therefore, a new open (non-periodic) boundary is required. In this paper, we have developed and validated a general parallel framework for open boundary conditions. This is a non-trivial enabling technology that could be used in all open boundary systems and all particle-based Lagrangian simulations. We performed systematic 3D simulations of blood flow in arteriolar bifurcations and elucidated the biophysical mechanism of blood-plasma separation as well as quantified the effects of branch size and bifurcation angle on cell separation efficiency, which have not been addressed before. We also demonstrated the applicability of the methodology in arterial trees with multiple inlets and outlets.
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Affiliation(s)
- Kirill Lykov
- Institute of Computational Science, Faculty of Informatics, University of Lugano, Lugano, Switzerland
| | - Xuejin Li
- Division of Applied Mathematics, Brown University, Providence, Rhode Island, United States of America
| | - Huan Lei
- Pacific Northwest National Laboratory, Richland, Washington, United States of America,
| | - Igor V. Pivkin
- Institute of Computational Science, Faculty of Informatics, University of Lugano, Lugano, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
- * E-mail: (IVP); (GEK)
| | - George Em Karniadakis
- Division of Applied Mathematics, Brown University, Providence, Rhode Island, United States of America
- * E-mail: (IVP); (GEK)
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