1
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Thompson SB, Waldman MM, Jacobelli J. Polymerization power: effectors of actin polymerization as regulators of T lymphocyte migration through complex environments. FEBS J 2022; 289:6154-6171. [PMID: 34273243 PMCID: PMC8761786 DOI: 10.1111/febs.16130] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 05/24/2021] [Accepted: 07/16/2021] [Indexed: 11/26/2022]
Abstract
During their life span, T cells are tasked with patrolling the body for potential pathogens. To do so, T cells migrate through numerous distinct anatomical sites and tissue environments with different biophysical characteristics. To migrate through these different environments, T cells use various motility strategies that rely on actin network remodeling to generate shape changes and mechanical forces. In this review, we initially discuss the migratory journey of T cells and then cover the actin polymerization effectors at play in T cells, and finally, we focus on the function of these effectors of actin cytoskeleton remodeling in mediating T-cell migration through diverse tissue environments. Specifically, we will discuss the current state of the field pertaining to our understanding of the roles in T-cell migration played by members of the three main families of actin polymerization machinery: the Arp2/3 complex; formin proteins; and Ena/VASP proteins.
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Affiliation(s)
- Scott B. Thompson
- Department of Immunology and Microbiology, University of Colorado School of Medicine
| | - Monique M. Waldman
- Department of Immunology and Microbiology, University of Colorado School of Medicine
- Barbara Davis Research Center, University of Colorado School of Medicine
| | - Jordan Jacobelli
- Department of Immunology and Microbiology, University of Colorado School of Medicine
- Barbara Davis Research Center, University of Colorado School of Medicine
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2
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Biomechanics of Neutrophil Tethers. Life (Basel) 2021; 11:life11060515. [PMID: 34073130 PMCID: PMC8230032 DOI: 10.3390/life11060515] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 05/22/2021] [Accepted: 05/25/2021] [Indexed: 12/11/2022] Open
Abstract
Leukocytes, including neutrophils, propelled by blood flow, can roll on inflamed endothelium using transient bonds between selectins and their ligands, and integrins and their ligands. When such receptor–ligand bonds last long enough, the leukocyte microvilli become extended and eventually form thin, 20 µm long tethers. Tether formation can be observed in blood vessels in vivo and in microfluidic flow chambers. Tethers can also be extracted using micropipette aspiration, biomembrane force probe, optical trap, or atomic force microscopy approaches. Here, we review the biomechanical properties of leukocyte tethers as gleaned from such measurements and discuss the advantages and disadvantages of each approach. We also review and discuss viscoelastic models that describe the dependence of tether formation on time, force, rate of loading, and cell activation. We close by emphasizing the need to combine experimental observations with quantitative models and computer simulations to understand how tether formation is affected by membrane tension, membrane reservoir, and interactions of the membrane with the cytoskeleton.
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3
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Puhr-Westerheide D, Schink SJ, Fabritius M, Mittmann L, Hessenauer MET, Pircher J, Zuchtriegel G, Uhl B, Holzer M, Massberg S, Krombach F, Reichel CA. Neutrophils promote venular thrombosis by shaping the rheological environment for platelet aggregation. Sci Rep 2019; 9:15932. [PMID: 31685838 PMCID: PMC6828708 DOI: 10.1038/s41598-019-52041-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 10/12/2019] [Indexed: 12/24/2022] Open
Abstract
In advanced inflammatory disease, microvascular thrombosis leads to the interruption of blood supply and provokes ischemic tissue injury. Recently, intravascularly adherent leukocytes have been reported to shape the blood flow in their immediate vascular environment. Whether these rheological effects are relevant for microvascular thrombogenesis remains elusive. Employing multi-channel in vivo microscopy, analyses in microfluidic devices, and computational modeling, we identified a previously unanticipated role of leukocytes for microvascular clot formation in inflamed tissue. For this purpose, neutrophils adhere at distinct sites in the microvasculature where these immune cells effectively promote thrombosis by shaping the rheological environment for platelet aggregation. In contrast to larger (lower-shear) vessels, this process in high-shear microvessels does not require fibrin generation or extracellular trap formation, but involves GPIbα-vWF and CD40-CD40L-dependent platelet interactions. Conversely, interference with these cellular interactions substantially compromises microvascular clotting. Thus, leukocytes shape the rheological environment in the inflamed venular microvasculature for platelet aggregation thereby effectively promoting the formation of blood clots. Targeting this specific crosstalk between the immune system and the hemostatic system might be instrumental for the prevention and treatment of microvascular thromboembolic pathologies, which are inaccessible to invasive revascularization strategies.
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Affiliation(s)
- Daniel Puhr-Westerheide
- Walter Brendel Centre of Experimental Medicine, Klinikum der Universität München, Ludwig-Maximilians-Universität München, Munich, Germany.,Department of Radiology, University Hospital, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Severin J Schink
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, USA
| | - Matthias Fabritius
- Walter Brendel Centre of Experimental Medicine, Klinikum der Universität München, Ludwig-Maximilians-Universität München, Munich, Germany.,Department of Radiology, University Hospital, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Laura Mittmann
- Walter Brendel Centre of Experimental Medicine, Klinikum der Universität München, Ludwig-Maximilians-Universität München, Munich, Germany.,Department of Otorhinolaryngology, Klinikum der Universität München, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Maximilian E T Hessenauer
- Walter Brendel Centre of Experimental Medicine, Klinikum der Universität München, Ludwig-Maximilians-Universität München, Munich, Germany.,Department of Plastic and Hand Surgery, Friedrich Alexander University Erlangen Nuernberg, Erlangen, Germany
| | - Joachim Pircher
- Walter Brendel Centre of Experimental Medicine, Klinikum der Universität München, Ludwig-Maximilians-Universität München, Munich, Germany.,Department of Cardiology, Klinikum der Universität München, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Gabriele Zuchtriegel
- Walter Brendel Centre of Experimental Medicine, Klinikum der Universität München, Ludwig-Maximilians-Universität München, Munich, Germany.,Department of Otorhinolaryngology, Klinikum der Universität München, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Bernd Uhl
- Walter Brendel Centre of Experimental Medicine, Klinikum der Universität München, Ludwig-Maximilians-Universität München, Munich, Germany.,Department of Otorhinolaryngology, Klinikum der Universität München, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Martin Holzer
- Walter Brendel Centre of Experimental Medicine, Klinikum der Universität München, Ludwig-Maximilians-Universität München, Munich, Germany.,Department of Otorhinolaryngology, Klinikum der Universität München, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Steffen Massberg
- Department of Cardiology, Klinikum der Universität München, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Fritz Krombach
- Walter Brendel Centre of Experimental Medicine, Klinikum der Universität München, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Christoph A Reichel
- Walter Brendel Centre of Experimental Medicine, Klinikum der Universität München, Ludwig-Maximilians-Universität München, Munich, Germany. .,Department of Otorhinolaryngology, Klinikum der Universität München, Ludwig-Maximilians-Universität München, Munich, Germany.
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4
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Effector and Regulatory T Cells Roll at High Shear Stress by Inducible Tether and Sling Formation. Cell Rep 2019; 21:3885-3899. [PMID: 29281835 DOI: 10.1016/j.celrep.2017.11.099] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 10/04/2017] [Accepted: 11/28/2017] [Indexed: 01/07/2023] Open
Abstract
The adaptive immune response involves T cell differentiation and migration to sites of inflammation. T cell trafficking is initiated by rolling on inflamed endothelium. Tethers and slings, discovered in neutrophils, facilitate cell rolling at high shear stress. Here, we demonstrate that the ability to form tethers and slings during rolling is highly inducible in T helper 1 (Th1), Th17, and regulatory T (Treg) cells but less in Th2 cells. In vivo, endogenous Treg cells rolled stably in cremaster venules at physiological shear stress. Quantitative dynamic footprinting nanoscopy of Th1, Th17, and Treg cells uncovered the formation of multiple tethers per cell. Human Th1 cells also showed tethers and slings. RNA sequencing (RNA-seq) revealed the induction of cell migration and cytoskeletal genes in sling-forming cells. We conclude that differentiated CD4 T cells stabilize rolling by inducible tether and sling formation. These phenotypic changes approximate the adhesion phenotype of neutrophils and support CD4 T cell access to sites of inflammation.
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5
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Marki A, Gutierrez E, Mikulski Z, Groisman A, Ley K. Microfluidics-based side view flow chamber reveals tether-to-sling transition in rolling neutrophils. Sci Rep 2016; 6:28870. [PMID: 27357741 PMCID: PMC4928115 DOI: 10.1038/srep28870] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 06/06/2016] [Indexed: 12/13/2022] Open
Abstract
Neutrophils rolling at high shear stress (above 6 dyn/cm2) form tethers in the rear and slings in the front. Here, we developed a novel photo-lithographically fabricated, silicone(PDMS)-based side-view flow chamber to dynamically visualize tether and sling formation. Fluorescently membrane-labeled mouse neutrophils rolled on P-selectin substrate at 10 dyn/cm2. Most rolling cells formed 5 tethers that were 2–30 μm long. Breaking of a single tether caused a reproducible forward microjump of the cell, showing that the tether was load-bearing. About 15% of all tether-breaking events resulted in slings. The tether-to-sling transition was fast (<100 ms) with no visible material extending above the rolling cell, suggesting a very low bending modulus of the tether. The sling downstream of the rolling cell aligned according to the streamlines before landing on the flow chamber. These new observations explain how slings form from tethers and provide insight into their biomechanical properties.
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Affiliation(s)
- Alex Marki
- La Jolla Institute for Allergy and Immunology, La Jolla, CA, USA
| | - Edgar Gutierrez
- Department of Physics and University of California San Diego, La Jolla, CA, USA
| | | | - Alex Groisman
- Department of Physics and University of California San Diego, La Jolla, CA, USA
| | - Klaus Ley
- La Jolla Institute for Allergy and Immunology, La Jolla, CA, USA.,Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
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6
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Takeishi N, Imai Y, Ishida S, Omori T, Kamm RD, Ishikawa T. Cell adhesion during bullet motion in capillaries. Am J Physiol Heart Circ Physiol 2016; 311:H395-403. [PMID: 27261363 DOI: 10.1152/ajpheart.00241.2016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 05/31/2016] [Indexed: 01/13/2023]
Abstract
A numerical analysis is presented of cell adhesion in capillaries whose diameter is comparable to or smaller than that of the cell. In contrast to a large number of previous efforts on leukocyte and tumor cell rolling, much is still unknown about cell motion in capillaries. The solid and fluid mechanics of a cell in flow was coupled with a slip bond model of ligand-receptor interactions. When the size of a capillary was reduced, the cell always transitioned to "bullet-like" motion, with a consequent decrease in the velocity of the cell. A state diagram was obtained for various values of capillary diameter and receptor density. We found that bullet motion enables firm adhesion of a cell to the capillary wall even for a weak ligand-receptor binding. We also quantified effects of various parameters, including the dissociation rate constant, the spring constant, and the reactive compliance on the characteristics of cell motion. Our results suggest that even under the interaction between P-selectin glycoprotein ligand-1 (PSGL-1) and P-selectin, which is mainly responsible for leukocyte rolling, a cell is able to show firm adhesion in a small capillary. These findings may help in understanding such phenomena as leukocyte plugging and cancer metastasis.
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Affiliation(s)
- Naoki Takeishi
- Graduate School of Biomedical Engineering, Tohoku University, Aoba, Sendai, Japan
| | - Yohsuke Imai
- School of Engineering, Tohoku University, Aoba, Sendai, Japan;
| | - Shunichi Ishida
- Graduate School of Biomedical Engineering, Tohoku University, Aoba, Sendai, Japan
| | - Toshihiro Omori
- School of Engineering, Tohoku University, Aoba, Sendai, Japan
| | - Roger D Kamm
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts; and Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Takuji Ishikawa
- Graduate School of Biomedical Engineering, Tohoku University, Aoba, Sendai, Japan; School of Engineering, Tohoku University, Aoba, Sendai, Japan
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7
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Omori T, Imai Y, Kikuchi K, Ishikawa T, Yamaguchi T. Hemodynamics in the microcirculation and in microfluidics. Ann Biomed Eng 2014; 43:238-57. [PMID: 25398331 DOI: 10.1007/s10439-014-1180-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 11/04/2014] [Indexed: 12/20/2022]
Abstract
Hemodynamics in microcirculation is important for hemorheology and several types of circulatory disease. Although hemodynamics research has a long history, the field continues to expand due to recent advancements in numerical and experimental techniques at the micro-and nano-scales. In this paper, we review recent computational and experimental studies of blood flow in microcirculation and microfluidics. We first focus on the computational studies of red blood cell (RBC) dynamics, from the single cellular level to mesoscopic multiple cellular flows, followed by a review of recent computational adhesion models for white blood cells, platelets, and malaria-infected RBCs, in which the cell adhesion to the vascular wall is essential for cellular function. Recent developments in optical microscopy have enabled the observation of flowing blood cells in microfluidics. Experimental particle image velocimetry and particle tracking velocimetry techniques are described in this article. Advancements in micro total analysis system technologies have facilitated flowing cell separation with microfluidic devices, which can be used for biomedical applications, such as a diagnostic tool for breast cancer or large intestinal tumors. In this paper, cell-separation techniques are reviewed for microfluidic devices, emphasizing recent advances and the potential of this fast-evolving research field in the near future.
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Affiliation(s)
- Toshihiro Omori
- Department of Bioengineering and Robotics, Tohoku University, Aoba 6-6-01, Sendai, Miyagi, Japan,
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8
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Lamberti G, Prabhakarpandian B, Garson C, Smith A, Pant K, Wang B, Kiani MF. Bioinspired microfluidic assay for in vitro modeling of leukocyte-endothelium interactions. Anal Chem 2014; 86:8344-51. [PMID: 25135319 PMCID: PMC4139165 DOI: 10.1021/ac5018716] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Accepted: 07/28/2014] [Indexed: 01/08/2023]
Abstract
Current in vitro models of the leukocyte adhesion cascade cannot be used for real-time studies of the entire leukocyte adhesion cascade, including rolling, adhesion, and migration in a single assay. In this study, we have developed and validated a novel bioinspired microfluidic assay (bMFA) and used it to test the hypothesis that blocking of specific steps in the adhesion/migration cascade significantly affects other steps of the cascade. The bMFA consists of an endothelialized microvascular network in communication with a tissue compartment via a 3 μm porous barrier. Human neutrophils in bMFA preferentially adhered to activated human endothelial cells near bifurcations with rolling and adhesion patterns in close agreement with in vivo observations. Treating endothelial cells with monoclonal antibodies to E-selectin or ICAM-1 or treating neutrophils with wortmannin reduced rolling, adhesion, and migration of neutrophils to 60%, 20%, and 18% of their respective control values. Antibody blocking of specific steps in the adhesion/migration cascade (e.g., mAb to E-selectin) significantly downregulated other steps of the cascade (e.g., migration). This novel in vitro assay provides a realistic human cell based model for basic science studies, identification of new treatment targets, selection of pathways to target validation, and rapid screening of candidate agents.
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Affiliation(s)
- Giuseppina Lamberti
- Department
of Mechanical Engineering, Temple University, 1947 N. 12th street, Philadelphia, Pennsylvania 19122, United States
| | | | - Charles Garson
- Biomedical
Technology, CFD Research Corporation, 701 McMillian Way, Huntsville, Alabama 35806, United
States
| | - Ashley Smith
- Biomedical
Technology, CFD Research Corporation, 701 McMillian Way, Huntsville, Alabama 35806, United
States
| | - Kapil Pant
- Biomedical
Technology, CFD Research Corporation, 701 McMillian Way, Huntsville, Alabama 35806, United
States
| | - Bin Wang
- Department
of Mechanical Engineering, Temple University, 1947 N. 12th street, Philadelphia, Pennsylvania 19122, United States
- Department
of Biomedical Engineering, Widener University, One University Place, Chester, Pennsylvania 19013-5792, United States
| | - Mohammad F. Kiani
- Department
of Mechanical Engineering, Temple University, 1947 N. 12th street, Philadelphia, Pennsylvania 19122, United States
- Department
of Radiation Oncology, Temple University
School of Medicine, 3500
N. Broad Street, Philadelphia, Pennsylvania 19140, United States
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9
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Zabetian M, Saidi MS, Shafii MB, Saidi MH. Separation of microparticles suspended in a minichannel using laser radiation pressure. APPLIED OPTICS 2013; 52:4950-8. [PMID: 23852211 DOI: 10.1364/ao.52.004950] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 05/30/2013] [Indexed: 05/20/2023]
Abstract
Optical separation, which is a contactless and accurate technique, has been mostly used to manipulate single particles. This work mainly aims to present an effective technique for optical propulsion and separation of a group of microscopic particles that are suspended in liquids. An experimental study is conducted to assess the effect of radiation pressure of a high-power laser on a dilute dispersion of microparticles in water using microscopic image analysis. Results of separation experiments indicate that the manipulation mechanism is capable of sorting the microscopic particles in two size classes. Compared to common optical separators, this configuration has a benefit of separating many particles simultaneously.
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Affiliation(s)
- Mohammad Zabetian
- Center of Excellence in Energy Conversion, School of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
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10
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BAI BOFENG, LUO ZHENGYUAN, LU TIANJIAN, XU FENG. NUMERICAL SIMULATION OF CELL ADHESION AND DETACHMENT IN MICROFLUIDICS. J MECH MED BIOL 2013. [DOI: 10.1142/s0219519413500024] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Inspired by the complex biophysical processes of cell adhesion and detachment under blood flow in vivo, numerous novel microfluidic devices have been developed to manipulate, capture, and separate bio-particles for various applications, such as cell analysis and cell enumeration. However, the underlying physical mechanisms are yet unclear, which has limited the further development of microfluidic devices and point-of-care (POC) systems. Mathematical modeling is an enabling tool to study the physical mechanisms of biological processes for its relative simplicity, low cost, and high efficiency. Recent development in computation technology for multiphase flow simulation enables the theoretical study of the complex flow processes of cell adhesion and detachment in microfluidics. Various mathematical methods (e.g., front tracking method, level set method, volume of fluid (VOF) method, fluid–solid interaction method, and particulate modeling method) have been developed to investigate the effects of cell properties (i.e., cell membrane, cytoplasma, and nucleus), flow conditions, and microchannel structures on cell adhesion and detachment in microfluidic channels. In this paper, with focus on our own simulation results, we review these methods and compare their advantages and disadvantages for cell adhesion/detachment modeling. The mathematical approaches discussed here would allow us to study microfluidics for cell capture and separation, and to develop more effective POC devices for disease diagnostics.
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Affiliation(s)
- BOFENG BAI
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, P.R. China
| | - ZHENGYUAN LUO
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, P.R. China
| | - TIANJIAN LU
- Biomedical Engineering and Biomechanics Center, Xi'an Jiaotong University, P.R. China
| | - FENG XU
- Biomedical Engineering and Biomechanics Center, Xi'an Jiaotong University, P.R. China
- School of Life Science and Technology, Xi'an Jiaotong University, P.R. China
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11
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Bianchi E, Molteni R, Pardi R, Dubini G. Microfluidics for in vitro biomimetic shear stress-dependent leukocyte adhesion assays. J Biomech 2012. [PMID: 23200903 DOI: 10.1016/j.jbiomech.2012.10.024] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Recruitment of leukocytes from blood to tissues is a multi-step process playing a major role in the activation of inflammatory responses. Tethering and rolling of leukocytes along the vessel wall, followed by arrest and transmigration through the endothelium result from chemoattractant-dependent signals, inducing adhesive and migratory events. Shear forces exerted by the blood flow on leukocytes induce rolling via selectin-mediated interactions with endothelial cells and increase the probability of leukocytes to engage their chemokine receptors, facilitating integrin activation and consequent arrest. Flow-derived shear forces generate mechanical stimuli concurring with biochemical signals in the modulation of leukocyte-endothelial cell interactions. In the last few years, a host of in vitro studies have clarified the biochemical adhesion cascade and the role of shear stress in leukocyte extravasation. The limitation of the static environment in Boyden devices has been overcome both by the use of parallel-plate flow chambers and by custom models mimicking the in vivo conditions, along with widespread microfluidic approaches to in vitro modeling. These devices create an in vitro biomimetic environment where the multi-step transmigration process can be imaged and quantified under mechanical and biochemical controlled conditions, including fluid dynamic settings, channel design, materials and surface coatings. This paper reviews the technological solutions recently proposed to model, observe and quantify leukocyte adhesion behavior under shear flow, with a final survey of high-throughput solutions featuring multiple parallel assays as well as thorough and time-saving statistical interpretation of the experimental results.
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Affiliation(s)
- Elena Bianchi
- LaBS-Laboratory of Biological Structure Mechanics, Department of Structural Engineering, Politecnico di Milano, Milan, Italy.
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12
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Ha H, Nam KH, Lee SJ. Hybrid PIV-PTV technique for measuring blood flow in rat mesenteric vessels. Microvasc Res 2012; 84:242-8. [PMID: 22820216 DOI: 10.1016/j.mvr.2012.07.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 07/06/2012] [Accepted: 07/10/2012] [Indexed: 11/30/2022]
Abstract
The micro-particle tracking velocimetry (μ-PTV) technique is used to obtain the velocity fields of blood flow in the microvasculature under in vivo conditions because it can provide the blood velocity distribution in microvessels with high spatial resolution. The in vivo μ-PTV technique usually requires a few to tens of seconds to obtain a whole velocity profile across the vessel diameter because of the limited number density of tracer particles under in vivo conditions. Thus, the μ-PTV technique alone is limited in measuring unsteady blood flows that fluctuate irregularly due to the heart beating and muscle movement in surrounding tissues. In this study, a new hybrid PIV-PTV technique was established by combining PTV and particle image velocimetry (PIV) techniques to resolve the drawbacks of the μ-PTV method in measuring blood flow in microvessels under in vivo conditions. Images of red blood cells (RBCs) and fluorescent particles in rat mesenteric vessels were obtained simultaneously. Temporal variations of the centerline blood velocity were monitored using a fast Fourier transform-based cross-correlation PIV method. The fluorescence particle images were analyzed using the μ-PTV technique to extract the spatial distribution of the velocity vectors. Data from the μ-PTV and PIV methods were combined to obtain a better estimate of the velocity profile in actual blood flow. This technique will be useful in investigating hemodynamics in microcirculation by measuring unsteady irregular blood flows more accurately.
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Affiliation(s)
- Hojin Ha
- Department of Mechanical Engineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang 790-784, Republic of Korea
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13
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Zhang S, Cheng J, Qin YX. Mechanobiological modulation of cytoskeleton and calcium influx in osteoblastic cells by short-term focused acoustic radiation force. PLoS One 2012; 7:e38343. [PMID: 22701628 PMCID: PMC3368843 DOI: 10.1371/journal.pone.0038343] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 05/03/2012] [Indexed: 01/27/2023] Open
Abstract
Mechanotransduction has demonstrated potential for regulating tissue adaptation in vivo and cellular activities in vitro. It is well documented that ultrasound can produce a wide variety of biological effects in biological systems. For example, pulsed ultrasound can be used to noninvasively accelerate the rate of bone fracture healing. Although a wide range of studies has been performed, mechanism for this therapeutic effect on bone healing is currently unknown. To elucidate the mechanism of cellular response to mechanical stimuli induced by pulsed ultrasound radiation, we developed a method to apply focused acoustic radiation force (ARF) (duration, one minute) on osteoblastic MC3T3-E1 cells and observed cellular responses to ARF using a spinning disk confocal microscope. This study demonstrates that the focused ARF induced F-actin cytoskeletal rearrangement in MC3T3-E1 cells. In addition, these cells showed an increase in intracellular calcium concentration following the application of focused ARF. Furthermore, passive bending movement was noted in primary cilium that were treated with focused ARF. Cell viability was not affected. Application of pulsed ultrasound radiation generated only a minimal temperature rise of 0.1°C, and induced a streaming resulting fluid shear stress of 0.186 dyne/cm(2), suggesting that hyperthermia and acoustic streaming might not be the main causes of the observed cell responses. In conclusion, these data provide more insight in the interactions between acoustic mechanical stress and osteoblastic cells. This experimental system could serve as basis for further exploration of the mechanosensing mechanism of osteoblasts triggered by ultrasound.
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Affiliation(s)
- Shu Zhang
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, United States of America
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14
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Fu Y, Kunz R, Wu J, Dong C. Study of local hydrodynamic environment in cell-substrate adhesion using side-view μPIV technology. PLoS One 2012; 7:e30721. [PMID: 22363477 PMCID: PMC3281875 DOI: 10.1371/journal.pone.0030721] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Accepted: 12/20/2011] [Indexed: 01/10/2023] Open
Abstract
Tumor cell adhesion to the endothelium under shear flow conditions is a critical step that results in circulation-mediated tumor metastasis. This study presents experimental and computational techniques for studying the local hydrodynamic environment around adherent cells and how local shear conditions affect cell-cell interactions on the endothelium in tumor cell adhesion. To study the local hydrodynamic profile around heterotypic adherent cells, a side-view flow chamber assay coupled with micro particle imaging velocimetry (μPIV) technique was developed, where interactions between leukocytes and tumor cells in the near-endothelial wall region and the local shear flow environment were characterized. Computational fluid dynamics (CFD) simulations were also used to obtain quantitative flow properties around those adherent cells. Results showed that cell dimension and relative cell-cell positions had strong influence on local shear rates. The velocity profile above leukocytes and tumor cells displayed very different patterns. Larger cell deformations led to less disturbance to the flow. Local shear rates above smaller cells were observed to be more affected by relative positions between two cells.
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Affiliation(s)
- Yi Fu
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, China
- Bioengineering Department, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Robert Kunz
- Applied Research Laboratory, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Jianhua Wu
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, China
| | - Cheng Dong
- Bioengineering Department, Pennsylvania State University, University Park, Pennsylvania, United States of America
- * E-mail:
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Pospieszalska MK, Ley K. Chapter 8 Modeling Leukocyte Rolling. CURRENT TOPICS IN MEMBRANES 2009. [DOI: 10.1016/s1063-5823(09)64008-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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