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Platelets’ Nanomechanics and Morphology in Neurodegenerative Pathologies. Biomedicines 2022; 10:biomedicines10092239. [PMID: 36140340 PMCID: PMC9496241 DOI: 10.3390/biomedicines10092239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Revised: 08/26/2022] [Accepted: 08/30/2022] [Indexed: 11/17/2022] Open
Abstract
The imaging and force–distance curve modes of atomic force microscopy (AFM) are explored to compare the morphological and mechanical signatures of platelets from patients diagnosed with classical neurodegenerative diseases (NDDs) and healthy individuals. Our data demonstrate the potential of AFM to distinguish between the three NDDs—Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS) and Alzheimer’s disease (AD), and normal healthy platelets. The common features of platelets in the three pathologies are reduced membrane surface roughness, area and height, and enhanced nanomechanics in comparison with healthy cells. These changes might be related to general phenomena associated with reorganization in the platelet membrane morphology and cytoskeleton, a key factor for all platelets’ functions. Importantly, the platelets’ signatures are modified to a different extent in the three pathologies, most significant in ALS, less pronounced in PD and the least in AD platelets, which shows the specificity associated with each pathology. Moreover, different degree of activation, distinct pseudopodia and nanocluster formation characterize ALS, PD and AD platelets. The strongest alterations in the biophysical properties correlate with the highest activation of ALS platelets, which reflect the most significant changes in their nanoarchitecture. The specific platelet signatures that mark each of the studied pathologies can be added as novel biomarkers to the currently used diagnostic tools.
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Sachs L, Denker C, Greinacher A, Palankar R. Quantifying single-platelet biomechanics: An outsider's guide to biophysical methods and recent advances. Res Pract Thromb Haemost 2020; 4:386-401. [PMID: 32211573 PMCID: PMC7086474 DOI: 10.1002/rth2.12313] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 12/10/2019] [Accepted: 01/07/2020] [Indexed: 01/30/2023] Open
Abstract
Platelets are the key cellular components of blood primarily contributing to formation of stable hemostatic plugs at the site of vascular injury, thus preventing excessive blood loss. On the other hand, excessive platelet activation can contribute to thrombosis. Platelets respond to many stimuli that can be of biochemical, cellular, or physical origin. This drives platelet activation kinetics and plays a vital role in physiological and pathological situations. Currently used bulk assays are inadequate for comprehensive biomechanical assessment of single platelets. Individual platelets interact and respond differentially while modulating their biomechanical behavior depending on dynamic changes that occur in surrounding microenvironments. Quantitative description of such a phenomenon at single-platelet regime and up to nanometer resolution requires methodological approaches that can manipulate individual platelets at submicron scales. This review focusses on principles, specific examples, and limitations of several relevant biophysical methods applied to single-platelet analysis such as micropipette aspiration, atomic force microscopy, scanning ion conductance microscopy and traction force microscopy. Additionally, we are introducing a promising single-cell approach, real-time deformability cytometry, as an emerging biophysical method for high-throughput biomechanical characterization of single platelets. This review serves as an introductory guide for clinician scientists and beginners interested in exploring one or more of the above-mentioned biophysical methods to address outstanding questions in single-platelet biomechanics.
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Affiliation(s)
- Laura Sachs
- Institute of Immunology and Transfusion MedicineUniversity Medicine GreifswaldGreifswaldGermany
| | | | - Andreas Greinacher
- Institute of Immunology and Transfusion MedicineUniversity Medicine GreifswaldGreifswaldGermany
| | - Raghavendra Palankar
- Institute of Immunology and Transfusion MedicineUniversity Medicine GreifswaldGreifswaldGermany
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3
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Murakami M, Kano F, Murata M. LLO-mediated Cell Resealing System for Analyzing Intracellular Activity of Membrane-impermeable Biopharmaceuticals of Mid-sized Molecular Weight. Sci Rep 2018; 8:1946. [PMID: 29386585 PMCID: PMC5792490 DOI: 10.1038/s41598-018-20482-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 01/19/2018] [Indexed: 12/23/2022] Open
Abstract
Cell-based assays have become increasingly important in the preclinical studies for biopharmaceutical products such as specialty peptides, which are of interest owing to their high substrate specificity. However, many of the latter are membrane impermeable and must be physically introduced into cells to evaluate their intracellular activities. We previously developed a "cell-resealing technique" that exploited the temperature-dependent pore-forming activity of the streptococcal toxin, streptolysin O (SLO), that enabled us to introduce various molecules into cells for evaluation of their intracellular activities. In this study, we report a new cell resealing method, the listeriolysin O (LLO)-mediated resealing method, to deliver mid-sized, membrane-impermeable biopharmaceuticals into cells. We found that LLO-type resealing required no exogenous cytosol to repair the injured cell membrane and allowed the specific entry of mid-sized molecules into cells. We use this method to introduce either a membrane-impermeable, small compound (8-OH-cAMP) or specialty peptide (Akt-in), and demonstrated PKA activation or Akt inhibition, respectively. Collectively, the LLO-type resealing method is a user-friendly and reproducible intracellular delivery system for mid-sized membrane-impermeable molecules into cells and for evaluating their intracellular activities.
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Affiliation(s)
- Masataka Murakami
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan
| | - Fumi Kano
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan.,Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, Kanagawa, 226-8503, Japan
| | - Masayuki Murata
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan. .,Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, Kanagawa, 226-8503, Japan. .,Laboratoty of Frontier Image Analysis, Graduate School of Arts and Science, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan.
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Rheinlaender J, Vogel S, Seifert J, Schächtele M, Borst O, Lang F, Gawaz M, Schäffer TE. Imaging the elastic modulus of human platelets during thrombininduced activation using scanning ion conductance microscopy. Thromb Haemost 2017; 113:305-11. [DOI: 10.1160/th14-05-0414] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 09/28/2014] [Indexed: 01/19/2023]
Abstract
SummaryPlatelet activation plays a critical role in haemostasis and thrombosis. It is well-known that platelets generate contractile forces during activation. However, their mechanical material properties have rarely been investigated. Here, we use scanning ion conductance microscopy (SICM) to visualise morphological and mechanical properties of live human platelets at high spatial resolution. We found that their mean elastic modulus decreases during thrombin-induced activation by about a factor of two. We observed a similar softening of platelets during cytochalasin D-induced cytoskeleton depolymerisation. However, thrombin-induced temporal and spatial modulations of the elastic modulus were substantially different from cytochalasin D-mediated changes. We thereby provide new insights into the mechanics of haemostasis and establish SICM as a novel imaging platform for the ex vivo investigation of the mechanical properties of live platelets.
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5
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Nguyen TH. Single-molecule force spectroscopy applied to heparin-induced thrombocytopenia. J Mol Recognit 2016; 30. [PMID: 27790761 DOI: 10.1002/jmr.2585] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 09/13/2016] [Accepted: 09/19/2016] [Indexed: 01/01/2023]
Abstract
Heparin-induced thrombocytopenia (HIT), occurring up to approximately 1% to 5% of patients receiving the antithrombotic drug heparins, has a complex pathogenesis involving multiple partners ranging from small molecules to cells/platelets. Recently, insights into the mechanism of HIT have been achieved by using single-molecule force spectroscopy (SMFS), a methodology that allows direct measurements of interactions among HIT partners. Here, the potential of SMFS in unraveling the mechanism of the initial steps in the pathogenesis of HIT at single-molecule resolution is highlighted. The new findings ranging from the molecular binding strengths and kinetics to the determination of the boundary between risk and non-risk heparin drugs or platelet-surface and platelet-platelet interactions will be reviewed. These novel results together have contributed to elucidate the mechanisms underlying HIT and demonstrate how SMFS can be applied to develop safer drugs with a reduced risk profile.
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Affiliation(s)
- Thi-Huong Nguyen
- Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, 17475, Greifswald, Germany.,ZIK HIKE - Center for Innovation Competence, Humoral Immune Reactions in Cardiovascular Diseases, University of Greifswald, 17489, Greifswald, Germany
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6
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Nguyen TH, Palankar R, Bui VC, Medvedev N, Greinacher A, Delcea M. Rupture Forces among Human Blood Platelets at different Degrees of Activation. Sci Rep 2016; 6:25402. [PMID: 27146004 PMCID: PMC4857101 DOI: 10.1038/srep25402] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 04/18/2016] [Indexed: 11/21/2022] Open
Abstract
Little is known about mechanics underlying the interaction among platelets during activation and aggregation. Although the strength of a blood thrombus has likely major biological importance, no previous study has measured directly the adhesion forces of single platelet-platelet interaction at different activation states. Here, we filled this void first, by minimizing surface mediated platelet-activation and second, by generating a strong adhesion force between a single platelet and an AFM cantilever, preventing early platelet detachment. We applied our setup to measure rupture forces between two platelets using different platelet activation states, and blockade of platelet receptors. The rupture force was found to increase proportionally to the degree of platelet activation, but reduced with blockade of specific platelet receptors. Quantification of single platelet-platelet interaction provides major perspectives for testing and improving biocompatibility of new materials; quantifying the effect of drugs on platelet function; and assessing the mechanical characteristics of acquired/inherited platelet defects.
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Affiliation(s)
- Thi-Huong Nguyen
- Nanostructure Group, ZIK HIKE - Center for Innovation Competence, Humoral Immune Reactions in Cardiovascular Diseases, University of Greifswald, 17489 Greifswald, Germany.,Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, 17475 Greifswald, Germany
| | - Raghavendra Palankar
- Nanostructure Group, ZIK HIKE - Center for Innovation Competence, Humoral Immune Reactions in Cardiovascular Diseases, University of Greifswald, 17489 Greifswald, Germany.,Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, 17475 Greifswald, Germany
| | - Van-Chien Bui
- Nanostructure Group, ZIK HIKE - Center for Innovation Competence, Humoral Immune Reactions in Cardiovascular Diseases, University of Greifswald, 17489 Greifswald, Germany.,Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, 17475 Greifswald, Germany
| | - Nikolay Medvedev
- Nanostructure Group, ZIK HIKE - Center for Innovation Competence, Humoral Immune Reactions in Cardiovascular Diseases, University of Greifswald, 17489 Greifswald, Germany
| | - Andreas Greinacher
- Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, 17475 Greifswald, Germany
| | - Mihaela Delcea
- Nanostructure Group, ZIK HIKE - Center for Innovation Competence, Humoral Immune Reactions in Cardiovascular Diseases, University of Greifswald, 17489 Greifswald, Germany.,Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, 17475 Greifswald, Germany
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7
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Stewart SE, D'Angelo ME, Piantavigna S, Tabor RF, Martin LL, Bird PI. Assembly of streptolysin O pores assessed by quartz crystal microbalance and atomic force microscopy provides evidence for the formation of anchored but incomplete oligomers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:115-26. [DOI: 10.1016/j.bbamem.2014.10.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 09/20/2014] [Accepted: 10/03/2014] [Indexed: 11/24/2022]
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8
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Activation induced morphological changes and integrin αIIbβ3 activity of living platelets. Methods 2013; 60:179-85. [PMID: 23571313 PMCID: PMC3678024 DOI: 10.1016/j.ymeth.2013.03.034] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 03/04/2013] [Accepted: 03/30/2013] [Indexed: 11/22/2022] Open
Abstract
Platelets are essential in hemostasis. Upon activation they undergo a shape-change accompanied with receptor presentation. Atomic force microscopy (AFM) imaging and single molecule force spectroscopy (SMFS) were used as powerful tools for exploring morphological changes as well as receptor activities of platelets. Imaging time series was accomplished with and without fixation steps at the single platelet level. Hereby the response of mechanical stimulation of the platelet by the AFM cantilever tip was directly observed. We demonstrate that living and fixed platelets develop filopodia after a short activation time followed by their disappearance including cellular bleb formation. Thereafter a second filopodia formation (filopodia extrusion) was observed; those filopodia subsequently disappeared again, and finally platelets detached from the support due to cell death. We determined the influence of mechanical stress on the chronology of morphological changes of platelets and demonstrated shear force induced filopodia formation. Through recordings over several hours, topographical AFM images over the full platelet lifetime - from early activation up to apoptosis - are presented. SMFS measurements on living platelets allowed determining the activation state of the most prominent membrane receptor integrin αIIbβ3 at all different phases of activation. αIIbβ3 was fully activated, independent of the morphological state.
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Polyakov P, Soussen C, Duan J, Duval JFL, Brie D, Francius G. Automated force volume image processing for biological samples. PLoS One 2011; 6:e18887. [PMID: 21559483 PMCID: PMC3084721 DOI: 10.1371/journal.pone.0018887] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Accepted: 03/24/2011] [Indexed: 01/09/2023] Open
Abstract
Atomic force microscopy (AFM) has now become a powerful technique for investigating on a molecular level, surface forces, nanomechanical properties of deformable particles, biomolecular interactions, kinetics, and dynamic processes. This paper specifically focuses on the analysis of AFM force curves collected on biological systems, in particular, bacteria. The goal is to provide fully automated tools to achieve theoretical interpretation of force curves on the basis of adequate, available physical models. In this respect, we propose two algorithms, one for the processing of approach force curves and another for the quantitative analysis of retraction force curves. In the former, electrostatic interactions prior to contact between AFM probe and bacterium are accounted for and mechanical interactions operating after contact are described in terms of Hertz-Hooke formalism. Retraction force curves are analyzed on the basis of the Freely Jointed Chain model. For both algorithms, the quantitative reconstruction of force curves is based on the robust detection of critical points (jumps, changes of slope or changes of curvature) which mark the transitions between the various relevant interactions taking place between the AFM tip and the studied sample during approach and retraction. Once the key regions of separation distance and indentation are detected, the physical parameters describing the relevant interactions operating in these regions are extracted making use of regression procedure for fitting experiments to theory. The flexibility, accuracy and strength of the algorithms are illustrated with the processing of two force-volume images, which collect a large set of approach and retraction curves measured on a single biological surface. For each force-volume image, several maps are generated, representing the spatial distribution of the searched physical parameters as estimated for each pixel of the force-volume image.
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Affiliation(s)
- Pavel Polyakov
- Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, LCPME, UMR 7564, Nancy-Université, CNRS, Vandoeuvre lès Nancy, France
| | - Charles Soussen
- Centre de Recherche en Automatique de Nancy, CRAN, UMR 7039, Nancy-Université, CNRS, Vandoeuvre lès Nancy, France
| | - Junbo Duan
- Centre de Recherche en Automatique de Nancy, CRAN, UMR 7039, Nancy-Université, CNRS, Vandoeuvre lès Nancy, France
| | - Jérôme F. L. Duval
- Laboratoire Environnement et Minéralurgie, LEM, UMR 7569, Nancy-Université, CNRS, Vandoeuvre lès Nancy, France
| | - David Brie
- Centre de Recherche en Automatique de Nancy, CRAN, UMR 7039, Nancy-Université, CNRS, Vandoeuvre lès Nancy, France
- * E-mail: (GF); (DB)
| | - Grégory Francius
- Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, LCPME, UMR 7564, Nancy-Université, CNRS, Vandoeuvre lès Nancy, France
- * E-mail: (GF); (DB)
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10
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Shamova EV, Gorudko IV, Drozd ES, Chizhik SA, Martinovich GG, Cherenkevich SN, Timoshenko AV. Redox regulation of morphology, cell stiffness, and lectin-induced aggregation of human platelets. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2010; 40:195-208. [PMID: 21079947 DOI: 10.1007/s00249-010-0639-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Revised: 10/11/2010] [Accepted: 10/20/2010] [Indexed: 01/24/2023]
Abstract
Redox regulation and carbohydrate recognition are potent molecular mechanisms which can contribute to platelet aggregation in response to various stimuli. The purpose of this study is to investigate the relationship between these mechanisms and to examine whether cell surface glycocalyx and cell stiffness of human platelets are sensitive to the redox potential formed by glutathione. To this end, human platelets were treated with different concentrations (0.05 μM to 6 mM) and ratios of reduced or oxidized glutathione (GSH or GSSG), and platelet morphological, mechanical, and functional properties were determined using conventional light microscopy, atomic force microscopy, and lectin-induced cell aggregation analysis. It was found that lowering the glutathione redox potential changed platelet morphology and increased platelet stiffness as well as modulated nonuniformly platelet aggregation in response to plant lectins with different carbohydrate-binding specificity including wheat germ agglutinin, Sambucus nigra agglutinin, and Canavalia ensiformis agglutinin. Extracellular redox potential and redox buffering capacity of the GSSG/2GSH couple were shown to control the availability of specific lectin-binding glycoligands on the cell surface, while the intracellular glutathione redox state affected the general functional ability of platelets to be aggregated independently of the type of lectins. Our data provide the first experimental evidence that glutathione as a redox molecule can affect the mechanical stiffness of human platelets and induce changes of the cell surface glycocalyx, which may represent a new mechanism of redox regulation of intercellular contacts.
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Affiliation(s)
- Ekaterina V Shamova
- Department of Biophysics, Belarusian State University, Nezavisimosti Ave. 4, 220030 Minsk, Belarus.
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11
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Shu W, Shu YT, Shi HB, Fei LX, Lei W, Ming QG. An easy method to discover cell membrane antigen with atomic force microscopy. Mol Biol Rep 2007; 35:557-61. [PMID: 17668287 DOI: 10.1007/s11033-007-9122-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2007] [Accepted: 07/19/2007] [Indexed: 10/23/2022]
Abstract
Atomic force microscopy (AFM) obtains a high resolution at nanometer. In the current study, we found that, before and after adding CD34, CD44 or CD29 antibodies, the AFM images of mouse adipose tissue derived mesenchymal stem cells (ADMSCs) had significant changes in both cell morphous (shape) and the average roughness of cell membrane. However, there was no significant difference in the cell shape and the average roughness of cell membrane, after adding CD45 or CD144 antibodies. Therefore, we could use the AFM to scan cell shape or to calculate the average roughness changes of cell membrane to analyze the existence of cell membrane antigen qualitatively.
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Affiliation(s)
- Wang Shu
- Laboratory of Cardiovascular Medical Department, The General Hospital of Chinese People of Liberation Army, Fu Xin Road 28, Beijing, 100853, China.
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Beckmann MA, Venkataraman S, Doktycz MJ, Nataro JP, Sullivan CJ, Morrell-Falvey JL, Allison DP. Measuring cell surface elasticity on enteroaggregative Escherichia coli wild type and dispersin mutant by AFM. Ultramicroscopy 2006; 106:695-702. [PMID: 16682120 DOI: 10.1016/j.ultramic.2006.02.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2005] [Accepted: 02/10/2006] [Indexed: 11/24/2022]
Abstract
Enteroaggregative Escherichia coli (EAEC) is pathogenic and produces severe diarrhea in humans. A mutant of EAEC that does not produce dispersin, a cell surface protein, is not pathogenic. It has been proposed that dispersin imparts a positive charge to the bacterial cell surface allowing the bacteria to colonize on the negatively charged intestinal mucosa. However, physical properties of the bacterial cell surface, such as rigidity, may be influenced by the presence of dispersin and may contribute to pathogenicity. Using the system developed in our laboratory for mounting and imaging bacterial cells by atomic force microscopy (AFM), in liquid, on gelatin coated mica surfaces, studies were initiated to measure cell surface elasticity. This was carried out in both wild type EAEC, that produces dispersin, and the mutant that does not produce dispersin. This was accomplished using AFM force-distance (FD) spectroscopy on the wild type and mutant grown in liquid or on solid medium. Images in liquid and in air of both the wild-type and mutant grown in liquid and on solid media are presented. This work represents an initial step in efforts to understand the pathogenic role of the dispersin protein in the wild-type bacteria.
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Affiliation(s)
- M A Beckmann
- UT-ORNL Graduate School of Genome Science and Technology, The University of Tennessee, Knoxville, 37996-0840, USA
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Kasas S, Wang X, Hirling H, Marsault R, Huni B, Yersin A, Regazzi R, Grenningloh G, Riederer B, Forrò L, Dietler G, Catsicas S. Superficial and deep changes of cellular mechanical properties following cytoskeleton disassembly. ACTA ACUST UNITED AC 2005; 62:124-32. [PMID: 16145686 DOI: 10.1002/cm.20086] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The cytoskeleton, composed of actin filaments, intermediate filaments, and microtubules, is a highly dynamic supramolecular network actively involved in many essential biological mechanisms such as cellular structure, transport, movements, differentiation, and signaling. As a first step to characterize the biophysical changes associated with cytoskeleton functions, we have developed finite elements models of the organization of the cell that has allowed us to interpret atomic force microscopy (AFM) data at a higher resolution than that in previous work. Thus, by assuming that living cells behave mechanically as multilayered structures, we have been able to identify superficial and deep effects that could be related to actin and microtubule disassembly, respectively. In Cos-7 cells, actin destabilization with Cytochalasin D induced a decrease of the visco-elasticity close to the membrane surface, while destabilizing microtubules with Nocodazole produced a stiffness decrease only in deeper parts of the cell. In both cases, these effects were reversible. Cell softening was measurable with AFM at concentrations of the destabilizing agents that did not induce detectable effects on the cytoskeleton network when viewing the cells with fluorescent confocal microscopy. All experimental results could be simulated by our models. This technology opens the door to the study of the biophysical properties of signaling domains extending from the cell surface to deeper parts of the cell.
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Affiliation(s)
- S Kasas
- Institut des Neurosciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
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14
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Avci R, Schweitzer M, Boyd RD, Wittmeyer J, Steele A, Toporski J, Beech I, Arce FT, Spangler B, Cole KM, McKay DS. Comparison of antibody--antigen interactions on collagen measured by conventional immunological techniques and atomic force microscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:11053-11063. [PMID: 15568858 DOI: 10.1021/la036376i] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We have developed a means of using atomic force microscopy (AFM) to repeatedly localize a small area of interest (4 x 4 microm(2)) within a 0.5-cm(2) area on a heterogeneous sample, to obtain and localize high-resolution images and force measurements on nonideal samples (i.e., samples that better reflect actual biological systems, not prepared on atomically flat surfaces). We demonstrate the repeated localization and measurement of unbinding forces associated with antibody--antigen (ab--ag) interactions, by applying AFM in air and in liquid to visualize and measure polyclonal ab--ag interactions, using chicken collagen as a model system. We demonstrate that molecular interactions, in the form of ab--ag complexes, can be visualized by AFM when secondary antibodies are conjugated to 20-nm colloidal gold particles. We then compare those results with established immunological techniques, to demonstrate broader application of AFM technology to other systems. Data from AFM studies are compared with results obtained using immunological methods traditionally employed to investigate ab--ag interactions, including enzyme-linked immunosorbent assay, immunoblotting, and in situ immunofluorescence. Finally, using functionalized AFM tips with a flexible tether [poly(ethylene glycol) 800] to which a derivatized antibody was attached, we analyzed force curve data to measure the unbinding force of collagen antibody from its antigen, obtaining a value of approximately 90 +/- 40 pN with a MatLab code written to automate the analyses of force curves obtained in force--volume mode. The methodology we developed for embedded collagen sections can be readily applied to the investigation of other receptor--ligand interactions.
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Affiliation(s)
- Recep Avci
- Department of Physics, Montana State University, EPS 264, Bozeman, Montana 59715, USA.
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Stolz M, Raiteri R, Daniels AU, VanLandingham MR, Baschong W, Aebi U. Dynamic elastic modulus of porcine articular cartilage determined at two different levels of tissue organization by indentation-type atomic force microscopy. Biophys J 2004; 86:3269-83. [PMID: 15111440 PMCID: PMC1304192 DOI: 10.1016/s0006-3495(04)74375-1] [Citation(s) in RCA: 299] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Cartilage stiffness was measured ex vivo at the micrometer and nanometer scales to explore structure-mechanical property relationships at smaller scales than has been done previously. A method was developed to measure the dynamic elastic modulus, |E(*)|, in compression by indentation-type atomic force microscopy (IT AFM). Spherical indenter tips (radius = approximately 2.5 microm) and sharp pyramidal tips (radius = approximately 20 nm) were employed to probe micrometer-scale and nanometer-scale response, respectively. |E(*)| values were obtained at 3 Hz from 1024 unloading response curves recorded at a given location on subsurface cartilage from porcine femoral condyles. With the microsphere tips, the average modulus was approximately 2.6 MPa, in agreement with available millimeter-scale data, whereas with the sharp pyramidal tips, it was typically 100-fold lower. In contrast to cartilage, measurements made on agarose gels, a much more molecularly amorphous biomaterial, resulted in the same average modulus for both indentation tips. From results of AFM imaging of cartilage, the micrometer-scale spherical tips resolved no fine structure except some chondrocytes, whereas the nanometer-scale pyramidal tips resolved individual collagen fibers and their 67-nm axial repeat distance. These results suggest that the spherical AFM tip is large enough to measure the aggregate dynamic elastic modulus of cartilage, whereas the sharp AFM tip depicts the elastic properties of its fine structure. Additional measurements of cartilage stiffness following enzyme action revealed that elastase digestion of the collagen moiety lowered the modulus at the micrometer scale. In contrast, digestion of the proteoglycans moiety by cathepsin D had little effect on |E(*)| at the micrometer scale, but yielded a clear stiffening at the nanometer scale. Thus, cartilage compressive stiffness is different at the nanometer scale compared to the overall structural stiffness measured at the micrometer and larger scales because of the fine nanometer-scale structure, and enzyme-induced structural changes can affect this scale-dependent stiffness differently.
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Affiliation(s)
- Martin Stolz
- M E Müller Institute for Structural Biology, Biozentrum University of Basel, Switzerland
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16
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Schaer-Zammaretti P, Ubbink J. Imaging of lactic acid bacteria with AFM--elasticity and adhesion maps and their relationship to biological and structural data. Ultramicroscopy 2003; 97:199-208. [PMID: 12801672 DOI: 10.1016/s0304-3991(03)00044-5] [Citation(s) in RCA: 134] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The adhesion of lactic acid bacteria to the intestinal epithelium is one of the most important factors determining probiotic ability of a bacterial strain. Studying bacterial adhesion requires knowledge of the structure and properties of the bacterial surface, which can be studied by atomic force microscopy under native conditions. The observation of the surface topography of bacteria from the species Lactobacillus crispatus, L. helveticus and L. johnsonii shows major differences between bacteria having a crystalline-like protein layer as part of the cell wall and those without such layers. Force volume images calculated into elasticity and adhesion force maps of different bacterial strains show that L. crispatus and L. helveticus have a surface with a homogeneous stiffness with no adhesion events. This is most likely caused by the S-layer, which completely covers the surface of the bacteria. We infer that the absence of adhesion peaks is caused by the semi-crystalline character of such protein layers, in agreement with the results obtained from electron microscopy. Analysis of a number of L. johnsonii strains shows that these bacteria have surface properties which strongly differ from the L. crispatus and L. helveticus strains. For L. johnsonii DMS20533 and L. johnsonii ATCC33200 high adhesion forces are observed, which can be related to a surface rich in polysaccharides. L. johnsonii ATCC332 has lower adhesion forces compared to the other two and, furthermore, the surface topography shows depressions. We suppose that this strain has a surface pattern consisting of crystalline-like proteins alternating with polysaccharide-rich domains. The wide variety in surface properties of lactobacilli could well have wide-ranging implications for food processing and for health benefits.
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Abstract
In this chapter I discussed the possibility of measuring elastic properties of living cells by AFM. One reason for using the AFM for this purpose is its ability to both measure locally the mechanics of a cell and to distinguish different regions of the cell. Since the AFM can be operated under physiological conditions cellular processes can be followed, for example, cytokinesis and the investigation of the migration of cells.
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Affiliation(s)
- Manfred Radmacher
- Drittes Physics Institute, Georg-August Universität, 37073 Göttingen, Germany
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Schär-Zammaretti P, Ziegler U, Forster I, Groscurth P, Spichiger-Keller UE. Potassium-selective atomic force microscopy on ion-releasing substrates and living cells. Anal Chem 2002; 74:4269-74. [PMID: 12199601 DOI: 10.1021/ac025605n] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new method for simultaneous mapping of cell topography and ion fluxes was developed. A highly sensitive ion sensor system was generated by coating atomic force microscopy tips with a PVC layer containing valinomycin, an ionophore for potassium. The activity of specific ions was traced on artificial ion-releasing PVC substrates. A boundary potential was generated owing to the selective exchange of a specific ion between coated tip and ion-releasing substrate. The boundary potential was detectable as a force induced by ion-selective electrostatic interactions. The selectivity coefficient of valinomycin for potassium against sodium (K(K,Na)f) was -2.5 +/- 0.5. Potassium efflux was measured on living MDCK-F1 cells expressing BK(Ca) channels. We could demonstrate localized areas of high potassium concentrations at the cell surface. The potassium efflux could be reversibly inhibited by thapsigargin, which is known to inhibit the efflux of potassium from BK(Ca) channels by suppression of calcium ATPase.
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Affiliation(s)
- Prisca Schär-Zammaretti
- Center for Chemical Sensors/Biosensors and Bioanalytical Chemistry, Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology, Zürich.
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Amino R, Martins RM, Procopio J, Hirata IY, Juliano MA, Schenkman S. Trialysin, a novel pore-forming protein from saliva of hematophagous insects activated by limited proteolysis. J Biol Chem 2002; 277:6207-13. [PMID: 11751887 DOI: 10.1074/jbc.m109874200] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have characterized a pore-forming lytic protein from the saliva of the hematophagous insect Triatoma infestans, a vector of Chagas disease. This protein, named trialysin, has 22 kDa and is present in the saliva at about 200 microg/ml. Purified trialysin forms voltage-dependent channels in planar lipid bilayers with conductance of 880 +/- 40 pS. It lyses protozoan parasites and bacteria indicating that it has a role in the control of microorganism growth in the salivary glands. At higher concentrations, but below those found in saliva, trialysin can also permeabilize and lyse mammalian cells, suggesting that it might also facilitate insect blood feeding by interfering with the cell response of the host. The translated cDNA sequence of trialysin shows a basic, lysine-rich protein in which the N-terminal region is predicted to form an amphipathic alpha-helical structure with positive charges on one side and hydrophobic amino acids on the opposite side. A synthetic peptide corresponding to this cationic amphipathic alpha-helix induces protozoan lysis and mammalian cell permeabilization, showing that this region is involved in lytic activity. However, the lytic peptide G6V32 is 10-fold less efficient than trialysin in lysing parasites and 100-fold less efficient in permeabilizing mammalian cells. Trialysin activity is about 10-fold reduced in salivary gland homogenates prepared in the presence of an irreversible serine-protease inhibitor. Since trialysin precursor contains an anionic pro-sequence of 33 amino acids contiguous to the cationic amphipathic putative alpha-helix, we propose that removal of the acidic pro-sequence by limited proteolysis activates trialysin by exposing this lytic basic amphipathic motif.
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Affiliation(s)
- Rogerio Amino
- Departamento de Microbiologia, Imunologia, e Parasitologia, Escola Paulista de Medicina, UNIFESP, São Paulo, S.P. 04023-062, Brazil
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Nagayama M, Haga H, Kawabata K. Drastic change of local stiffness distribution correlating to cell migration in living fibroblasts. CELL MOTILITY AND THE CYTOSKELETON 2001; 50:173-9. [PMID: 11807938 DOI: 10.1002/cm.10008] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Sequential images of the local stiffness distribution of living fibroblasts (NIH3T3) were captured under a culture condition using scanning probe microscopy in a force modulation mode. We found a clear relation between cell migration and local stiffness distribution on the cell: When cells were stationary at one position, the stiffness distribution of their cellular surface was quite stable. On the other hand, once the cells started to move, the stiffness in their nuclear regions drastically decreased. Possible explanations for the correlation between the cell migration and the cell stiffness are proposed.
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Affiliation(s)
- M Nagayama
- Division of Physics, Graduate School of Science, Hokkaido University, Sapporo, Japan.
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Mapping the Surface Characteristics of Polystyrene Microtiter Wells by a Multimode Scanning Force Microscopy Approach. J Colloid Interface Sci 2001. [DOI: 10.1006/jcis.2001.7800] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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