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De Leon SE, Cleuren L, Oo ZY, Stoddart PR, McArthur SL. Extending In-Plane Impedance Measurements from 2D to 3D Cultures: Design Considerations. Bioengineering (Basel) 2021; 8:11. [PMID: 33450860 PMCID: PMC7828367 DOI: 10.3390/bioengineering8010011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/21/2020] [Accepted: 12/29/2020] [Indexed: 11/22/2022] Open
Abstract
Three-dimensional (3D) cell cultures have recently emerged as tools for biologically modelling the human body. As 3D models make their way into laboratories there is a need to develop characterisation techniques that are sensitive enough to monitor the cells in real time and without the need for chemical labels. Impedance spectroscopy has been shown to address both of these challenges, but there has been little research into the full impedance spectrum and how the different components of the system affect the impedance signal. Here we investigate the impedance of human fibroblast cells in 2D and 3D collagen gel cultures across a broad range of frequencies (10 Hz to 5 MHz) using a commercial well with in-plane electrodes. At low frequencies in both 2D and 3D models it was observed that protein adsorption influences the magnitude of the impedance for the cell-free samples. This effect was eliminated once cells were introduced to the systems. Cell proliferation could be monitored in 2D at intermediate frequencies (30 kHz). However, the in-plane electrodes were unable to detect any changes in the impedance at any frequency when the cells were cultured in the 3D collagen gel. The results suggest that in designing impedance measurement devices, both the nature and distribution of the cells within the 3D culture as well as the architecture of the electrodes are key variables.
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Affiliation(s)
- Sorel E. De Leon
- Bioengineering Research Group, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, VIC 3122, Australia; (S.E.D.L.); (Z.Y.O.); (P.R.S.)
- Commonwealth Scientific and Industrial Research Organisation (CSIRO), Clayton, VIC 3168, Australia
| | - Lana Cleuren
- PXL University College, Hasselt University, 3500 Hasselt, Belgium;
| | - Zay Yar Oo
- Bioengineering Research Group, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, VIC 3122, Australia; (S.E.D.L.); (Z.Y.O.); (P.R.S.)
- Commonwealth Scientific and Industrial Research Organisation (CSIRO), Clayton, VIC 3168, Australia
| | - Paul R. Stoddart
- Bioengineering Research Group, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, VIC 3122, Australia; (S.E.D.L.); (Z.Y.O.); (P.R.S.)
| | - Sally L. McArthur
- Bioengineering Research Group, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, VIC 3122, Australia; (S.E.D.L.); (Z.Y.O.); (P.R.S.)
- Commonwealth Scientific and Industrial Research Organisation (CSIRO), Clayton, VIC 3168, Australia
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Nahid MA, Campbell CE, Fong KSK, Barnhill JC, Washington MA. An evaluation of the impact of clinical bacterial isolates on epithelial cell monolayer integrity by the electric Cell-Substrate Impedance Sensing (ECIS) method. J Microbiol Methods 2020; 169:105833. [PMID: 31904440 DOI: 10.1016/j.mimet.2020.105833] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 12/30/2019] [Accepted: 01/01/2020] [Indexed: 01/26/2023]
Abstract
Virulence is the relative capacity of a pathogenic microorganism to cause damage in susceptible host cells such as those found in airway passages and the gut. In this study, the effect of clinical bacterial isolates on the monolayer integrity of cultured human alveolar basal epithelial cells (A549) was evaluated using the Electric Cell-Substrate Impedance Sensing (ECIS) system. ECIS is a morphological biosensor which records electrical properties of cell-covered microelectrodes in an AC circuit including impedance (ohm), resistance (ohm), and capacitance (μFarad). In the current study, fluctuations in the electrical properties of cell-covered microelectrodes reflect dynamic changes in cell morphology resulting from disrupted cell monolayers following exposure to bacteria. Using the ECIS system, real-time changes of cell morphology and disruption of monolayer integrity of cell-cultures in vitro were revealed for A549 cells infected with either Pseudomonas aeruginosa, ESBL Escherichia coli, Staphylococcus aureus (MRSA), or Enterococcus (VRE). We determined empirically that the optimal signal response was obtained for resistance (ohm) measurements at 4000 hertz. Following infection of A549 cells, the data revealed that Pseudomonas aeruginosa resulted in little change in microelectrode resistance (ohm @4 kHz) as compared to pathogen-free controls within the first 12 h. In contrast, E. coli, MRSA, and VRE caused significant changes in electrode resistance (ohm @4 kHz) values in the infected cells compared to controls over the first 5 h. Resistance (ohm @4 kHz) changes were also observed in cell monolayers infected with different bacterial concentrations for all isolates over 24 h. The highest concentration of bacteria caused the measured resistance (ohm @4 kHz) to drop faster than its' immediate lower concentration, suggesting a dose-dependent effect. Compared to live bacteria, cells exposed to heat-killed bacteria did not show significant changes in resistance (ohm @4 kHz) over 48 h post-exposure. Functionally, cytokine responses were different between cells treated with live and heat-killed bacteria. Of note, live bacteria induced IFNγ, IL-13, and IL-1β production in A549 cells, whereas heat-killed bacteria induced IL-8 production suggesting a differential interaction with cells that could reveal the underlying causes of resistance (ohm @4 kHz) changes. Our findings indicate that ECIS provides a means to quantify, automate, and measure bacterial virulence, which may have broader implications governing the course of treatment compared to traditional methods alone.
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Affiliation(s)
- Md A Nahid
- United States Army Institute of Surgical Research, San Antonio, TX, United States.
| | - Carmen E Campbell
- Department of Clinical Investigation, Tripler Army Medical Center, Honolulu, HI, United States
| | - Keith S K Fong
- Department of Clinical Investigation, Tripler Army Medical Center, Honolulu, HI, United States
| | - Jason C Barnhill
- Department of Chemistry and Life Science, United States Military Academy, West Point, NY, United States
| | - Michael A Washington
- Department of Chemistry and Life Science, United States Military Academy, West Point, NY, United States
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Imaizumi Y, Goda T, Schaffhauser DF, Okada JI, Matsumoto A, Miyahara Y. Proton-sensing transistor systems for detecting ion leakage from plasma membranes under chemical stimuli. Acta Biomater 2017; 50:502-509. [PMID: 27956364 DOI: 10.1016/j.actbio.2016.12.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 12/07/2016] [Accepted: 12/07/2016] [Indexed: 01/01/2023]
Abstract
The membrane integrity of live cells is routinely evaluated for cytotoxicity induced by chemical or physical stimuli. Recent progress in bioengineering means that high-quality toxicity validation is required. Here, we report a pH-sensitive transistor system developed for the continuous monitoring of ion leakage from cell membranes upon challenge by toxic compounds. Temporal changes in pH were generated with high reproducibility via periodic flushing of HepG2 cells on a gate insulator of a proton-sensitive field-effect transistor with isotonic buffer solutions with/without NH4Cl. The pH transients at the point of NH4Cl addition/withdrawal originated from the free permeation of NH3 across the semi-permeable plasma membranes, and the proton sponge effect produced by the ammonia equilibrium. Irreversible attenuation of the pH transient was observed when the cells were subjected to a membrane-toxic reagent. Experiments and simulations proved that the decrease in the pH transient was proportional to the area of the ion-permeable pores on the damaged plasma membranes. The pH signal was correlated with the degree of hemolysis produced by the model reagents. The pH assay was sensitive to the formation of molecularly sized pores that were otherwise not measurable via detection of the leakage of hemoglobin, because the hydrodynamic radius of hemoglobin was greater than 3.1nm in the hemolysis assay. The pH transient was not disturbed by inherent ion-transporter activity. The ISFET assay was applied to a wide variety of cell types. The system presented here is fast, sensitive, practical and scalable, and will be useful for validating cytotoxins and nanomaterials. STATEMENT OF SIGNIFICANCE The plasma membrane toxicity and hemolysis are widely and routinely evaluated in biomaterials science and biomedical engineering. Despite the recent development of a variety of methods/materials for efficient gene/drug delivery systems to the cytosol, the methodologies for safety validation remain unchanged in many years while leaving some major issues such as sensitivity, accuracy, and fast response. The paper describes a new way of measuring the plasma membrane leakage in real time upon challenge by toxic reagents using a solid-state transistor that is sensitive to proton as the smallest indicator. Our system was reliable and was correlated to the results from hemolysis assay with advanced features in sensitivity, fast response, and wide applicability to chemical species. The downsizing and integration features of semiconductor fabrication technologies may realize cytotoxicity assays at the single-cell level in multi-parallel.
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Affiliation(s)
- Yuki Imaizumi
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062 Japan
| | - Tatsuro Goda
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062 Japan.
| | - Daniel F Schaffhauser
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062 Japan
| | - Jun-Ichi Okada
- Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8563, Japan
| | - Akira Matsumoto
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062 Japan
| | - Yuji Miyahara
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062 Japan.
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Liu Q, Wu C, Cai H, Hu N, Zhou J, Wang P. Cell-based biosensors and their application in biomedicine. Chem Rev 2014; 114:6423-61. [PMID: 24905074 DOI: 10.1021/cr2003129] [Citation(s) in RCA: 189] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Qingjun Liu
- Biosensor National Special Laboratory, Key Laboratory of Biomedical Engineering of the Ministry of Education, Department of Biomedical Engineering, Zhejiang University , Hangzhou 310027, China
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Liu F, Li F, Nordin AN, Voiculescu I. A novel cell-based hybrid acoustic wave biosensor with impedimetric sensing capabilities. SENSORS 2013; 13:3039-55. [PMID: 23459387 PMCID: PMC3658730 DOI: 10.3390/s130303039] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Revised: 01/28/2013] [Accepted: 02/20/2013] [Indexed: 11/16/2022]
Abstract
A novel multiparametric biosensor system based on living cells will be presented. The biosensor system includes two biosensing techniques on a single device: resonant frequency measurements and electric cell-substrate impedance sensing (ECIS). The multiparametric sensor system is based on the innovative use of the upper electrode of a quartz crystal microbalance (QCM) resonator as working electrode for the ECIS technique. The QCM acoustic wave sensor consists of a thin AT-cut quartz substrate with two gold electrodes on opposite sides. For integration of the QCM with the ECIS technique a semicircular counter electrode was fabricated near the upper electrode on the same side of the quartz crystal. Bovine aortic endothelial live cells (BAECs) were successfully cultured on this hybrid biosensor. Finite element modeling of the bulk acoustic wave resonator using COMSOL simulations was performed. Simultaneous gravimetric and impedimetric measurements performed over a period of time on the same cell culture were conducted to validate the device's sensitivity. The time necessary for the BAEC cells to attach and form a compact monolayer on the biosensor was 35~45 minutes for 1.5 × 10(4) cells/cm2 BAECs; 60 minutes for 2.0 × 10(4) cells/cm2 BAECs; 70 minutes for 3.0 × 10(4) cells/cm2 BAECs; and 100 minutes for 5.0 × 104 cells/cm2 BAECs. It was demonstrated that this time is the same for both gravimetric and impedimetric measurements. This hybrid biosensor will be employed in the future for water toxicity detection.
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Affiliation(s)
- Fei Liu
- Mechanical Engineering Department, City College of New York, New York, NY 10031, USA; E-Mail:
| | - Fang Li
- Mechanical Engineering Department, New York Institute of Technology, Old Westbury, NY 11568, USA; E-Mail:
| | - Anis Nurashikin Nordin
- Electrical and Computer Engineering, International Islamic University Malaysia, Jalan Gombak, Kuala Lumpur 53100, Malaysia; E-Mail:
| | - Ioana Voiculescu
- Mechanical Engineering Department, City College of New York, New York, NY 10031, USA; E-Mail:
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-212-650-5210; Fax: +1-212-650-8013
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6
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Male KB, Leung ACW, Montes J, Kamen A, Luong JHT. Probing inhibitory effects of nanocrystalline cellulose: inhibition versus surface charge. NANOSCALE 2012; 4:1373-9. [PMID: 22252333 DOI: 10.1039/c2nr11886f] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
NCC derived from different biomass sources was probed for its plausible cytotoxicity by electric cell-substrate impedance sensing (ECIS). Two different cell lines, Spodoptera frugiperda Sf9 insect cells and Chinese hamster lung fibroblast V79, were exposed to NCC and their spreading and viability were monitored and quantified by ECIS. Based on the 50%-inhibition concentration (ECIS(50)), none of the NCC produced was judged to have any significant cytotoxicity on these two cell lines. However, NCC derived from flax exhibited the most pronounced inhibition on Sf9 compared to hemp and cellulose powder. NCCs from flax and hemp pre-treated with pectate lyase were also less inhibitory than NCCs prepared from untreated flax and hemp. Results also suggested a correlation between the inhibitory effect and the carboxylic acid contents on the NCC.
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Affiliation(s)
- Keith B Male
- Biotechnology Research Institute, National Research Council Canada, 6100 Royalmount Avenue, Montreal, Quebec H4P 2R2, Canada
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7
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A cell-based impedance assay for monitoring transient receptor potential (TRP) ion channel activity. Biosens Bioelectron 2011; 26:2376-82. [DOI: 10.1016/j.bios.2010.10.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Revised: 10/08/2010] [Accepted: 10/11/2010] [Indexed: 01/29/2023]
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8
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Xiao C, Luong JH. A simple mathematical model for electric cell-substrate impedance sensing with extended applications. Biosens Bioelectron 2010; 25:1774-80. [DOI: 10.1016/j.bios.2009.12.025] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Revised: 12/19/2009] [Accepted: 12/21/2009] [Indexed: 10/20/2022]
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9
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Opp D, Wafula B, Lim J, Huang E, Lo JC, Lo CM. Use of electric cell-substrate impedance sensing to assess in vitro cytotoxicity. Biosens Bioelectron 2009; 24:2625-9. [PMID: 19230649 DOI: 10.1016/j.bios.2009.01.015] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2008] [Revised: 01/14/2009] [Accepted: 01/14/2009] [Indexed: 11/25/2022]
Abstract
In vitro assessment of cytotoxicity based on electrochemical impedance spectroscopy (EIS) needs more quantitative methods to analyze the alteration of cell morphology and motility, and hence the potential risk to human health. Here, we applied electric cell-substrate impedance sensing (ECIS) to evaluate dose-dependent responses of human umbilical vein endothelial cells exposed to cytochalasin B. To detect subtle changes in cell morphology, the frequency-dependent impedance data of the cell monolayer were measured and analyzed with a theoretical cell-electrode model. To detect the alternation of cell micromotion in response to cytochalasin B challenge, time-series impedance fluctuations of cell-covered electrodes were monitored and the values of power spectrum, variance, and variance of the increments were calculated to verify the difference. While a dose-dependent relationship was generally observed from the overall resistance of the cell monolayer, the analysis of frequency-dependent impedance and impedance fluctuations distinguished cytochalasin B levels as low as 0.1 microM. Our results show that cytochalasin B causes a decrease of junctional resistance between cells, an increase of membrane capacitance, and the reduction in micromotion.
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Affiliation(s)
- Daniel Opp
- Department of Physics, University of South Florida, Tampa, FL 33620-5700, United States
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10
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Male KB, Rao YK, Tzeng YM, Montes J, Kamen A, Luong JHT. Probing Inhibitory Effects of Antrodia camphorata Isolates Using Insect Cell-Based Impedance Spectroscopy: Inhibition vs Chemical Structure. Chem Res Toxicol 2008; 21:2127-33. [DOI: 10.1021/tx800202a] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Keith B. Male
- Biotechnology Research Institute, National Research Council Canada, Montreal, Quebec, Canada H4P 2R2, Institute of Biotechnology, Chaoyang University of Technology, Wufeng, 41349 Taiwan, Republic of China, and Department of Chemistry, University College Cork, Cork, Ireland
| | - Yerra Koteswara Rao
- Biotechnology Research Institute, National Research Council Canada, Montreal, Quebec, Canada H4P 2R2, Institute of Biotechnology, Chaoyang University of Technology, Wufeng, 41349 Taiwan, Republic of China, and Department of Chemistry, University College Cork, Cork, Ireland
| | - Yew-Min Tzeng
- Biotechnology Research Institute, National Research Council Canada, Montreal, Quebec, Canada H4P 2R2, Institute of Biotechnology, Chaoyang University of Technology, Wufeng, 41349 Taiwan, Republic of China, and Department of Chemistry, University College Cork, Cork, Ireland
| | - Johnny Montes
- Biotechnology Research Institute, National Research Council Canada, Montreal, Quebec, Canada H4P 2R2, Institute of Biotechnology, Chaoyang University of Technology, Wufeng, 41349 Taiwan, Republic of China, and Department of Chemistry, University College Cork, Cork, Ireland
| | - Amine Kamen
- Biotechnology Research Institute, National Research Council Canada, Montreal, Quebec, Canada H4P 2R2, Institute of Biotechnology, Chaoyang University of Technology, Wufeng, 41349 Taiwan, Republic of China, and Department of Chemistry, University College Cork, Cork, Ireland
| | - John H. T. Luong
- Biotechnology Research Institute, National Research Council Canada, Montreal, Quebec, Canada H4P 2R2, Institute of Biotechnology, Chaoyang University of Technology, Wufeng, 41349 Taiwan, Republic of China, and Department of Chemistry, University College Cork, Cork, Ireland
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11
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Balasubramanian L, Yip KP, Hsu TH, Lo CM. Impedance analysis of renal vascular smooth muscle cells. Am J Physiol Cell Physiol 2008; 295:C954-65. [PMID: 18684988 DOI: 10.1152/ajpcell.00009.2008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Impedance of renal vascular smooth muscle cells (VSMCs) cultured on microelectrodes was measured by electric cell-substrate impedance sensing. Changes in measured impedance as a function of frequency were compared with the calculated values obtained from an extended cell-electrode model to estimate the junctional resistance, distance between the ventral cell surface and the substratum, and apical and basolateral membrane capacitances of renal VSMCs. This cell-electrode model was derived to accommodate the slender and rectangular shape of VSMCs. The calculated changes in impedance (Z(cal)) based on the model agreed well with the experimental measurement (Z(exp)), and the percentage error defined as |(Z(cal)-Z(exp))/Z(exp)| was 1.0%. To test the sensitivity of the new model for capturing changes in cell-cell and cell-substrate interactions induced by changes in cellular environment, we then applied this model to analyze impedance changes induced by an integrin binding peptide in renal VSMCs. Our result demonstrates that integrin binding peptide decreases junctional resistance between cells, increases the distance between the basolateral cell surface and substratum, and increases the apical membrane capacitance, whereas the basolateral membrane capacitance stays relatively stable. This model provides a generic approach for impedance analysis of cell layers composed of slender, rectangular cells.
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Affiliation(s)
- Lavanya Balasubramanian
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida 33620-5700, USA
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12
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Spegel C, Heiskanen A, Skjolding L, Emnéus J. Chip Based Electroanalytical Systems for Cell Analysis. ELECTROANAL 2008. [DOI: 10.1002/elan.200704130] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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13
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Affiliation(s)
- Richard P Ellen
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
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14
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Batista da Silva AP, Lee W, Bajenova E, McCulloch CAG, Ellen RP. The major outer sheath protein of Treponema denticola inhibits the binding step of collagen phagocytosis in fibroblasts. Cell Microbiol 2004; 6:485-98. [PMID: 15056218 DOI: 10.1111/j.1462-5822.2004.00377.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Bacterial infections contribfute to the chronicity of connective tissue lesions in part by perturbing extracellular matrix remodelling processes. We examined a novel mechanism by which the major outer sheath protein (Msp) of the spirochaete Treponema denticola disrupts matrix remodelling mediated by intracellular digestion of collagen. The initial collagen-binding step of phagocytosis was examined in human gingival fibroblasts and Rat-2 fibroblasts. Cells were pretreated with Msp or vehicle, and binding of collagen-coated beads was measured by flow cytometry. Exposure to Msp induced a dose- and time-dependent decrease in cells that bound collagen beads; the inhibition of binding was reversed by absorption with anti-Msp antibodies. Msp-treated fibroblasts remained viable but underwent actin reorganization, including the assembly of a dense meshwork of subcortical actin filaments. Shear force assays showed that Msp abrogated collagen-binding interactions in the minimal affinity range required for stable adhesion. Fluorescence microscopy and immunoblotting showed equivalent amounts of beta1 integrin associated with collagen beads bound to Msp- and vehicle-treated cells. Photobleaching experiments found a similar percentage mobile fraction of beta1 integrins recovered in bleached areas of the plasma membrane. In contrast, Msp-induced inhibition of collagen binding was reversed by beta1 integrin affinity-activating antibodies and by latrunculin B, which prevented subcortical actin assembly. We conclude that native Msp of T. denticola inhibits the binding step of collagen phagocytosis in fibroblasts by inducing subcortical actin filament assembly and restricting affinity modulation of beta1 integrins. We suggest that, like Msp, bacterial toxins that target the cytoskeleton may also perturb the signalling networks required for cellular engagement of matrix ligands.
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Affiliation(s)
- Andre Paes Batista da Silva
- CIHR Group in Matrix Dynamics, University of Toronto, 124 Edward Street, Room 450, Toronto, Ontario, Canada M5G 1G6
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15
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Correia FF, Plummer AR, Ellen RP, Wyss C, Boches SK, Galvin JL, Paster BJ, Dewhirst FE. Two paralogous families of a two-gene subtilisin operon are widely distributed in oral treponemes. J Bacteriol 2004; 185:6860-9. [PMID: 14617650 PMCID: PMC262700 DOI: 10.1128/jb.185.23.6860-6869.2003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Certain oral treponemes express a highly proteolytic phenotype and have been associated with periodontal diseases. The periodontal pathogen Treponema denticola produces dentilisin, a serine protease of the subtilisin family. The two-gene operon prcA-prtP is required for expression of active dentilisin (PrtP), a putative lipoprotein attached to the treponeme's outer membrane or sheath. The purpose of this study was to examine the diversity and structure of treponemal subtilisin-like proteases in order to better understand their distribution and function. The complete sequences of five prcA-prtP operons were determined for Treponema lecithinolyticum, "Treponema vincentii," and two canine species. Partial operon sequences were obtained for T. socranskii subsp. 04 as well as 450- to 1,000-base fragments of prtP genes from four additional treponeme strains. Phylogenetic analysis demonstrated that the sequences fall into two paralogous families. The first family includes the sequence from T. denticola. Treponemes possessing this operon family express chymotrypsin-like protease activity and can cleave the substrate N-succinyl-alanyl-alanyl-prolyl-phenylalanine-p-nitroanilide (SAAPFNA). Treponemes possessing the second paralog family do not possess chymotrypsin-like activity or cleave SAAPFNA. Despite examination of a range of protein and peptide substrates, the specificity of the second protease family remains unknown. Each of the fully sequenced prcA and prtP genes contains a 5' hydrophobic leader sequence with a treponeme lipobox. The two paralogous families of treponeme subtilisins represent a new subgroup within the subtilisin family of proteases and are the only subtilisin lipoprotein family. The present study demonstrated that the subtilisin paralogs comprising a two-gene operon are widely distributed among treponemes.
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Affiliation(s)
- Frederick F Correia
- Department of Molecular Genetics, The Forsyth Institute, Boston, Massachusetts 02115, USA
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16
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Luong JHT. An Emerging Impedance Sensor Based on Cell-Protein Interactions: Applications in Cell Biology and Analytical Biochemistry. ANAL LETT 2003. [DOI: 10.1081/al-120026565] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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17
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Hug TS. Biophysical Methods for Monitoring Cell-Substrate Interactions in Drug Discovery. Assay Drug Dev Technol 2003; 1:479-88. [PMID: 15090185 DOI: 10.1089/154065803322163795] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Cell-substrate interactions are implicated in a number of relevant pathways for drug targets such as angiogenesis, arteriosclerosis, chronic inflammatory diseases, and carcinogenesis. Moreover, cell adhesion and cytoskeletal activity have served as valuable indicators for cytotoxicity, cell density, and cell morphology. This review focuses on impedance, capacitance, resonant frequency, and refractive index measurements for monitoring cell adhesion in real time and without the use of cell labeling. ECIS, QCM, and OWLS deliver information about the cell-substrate interactions, cell-cell contact, and the strength of cell adhesion. Because of high sensitivity of these assays, events down to the single cell level have been observed, and resolutions at the nanometer level of cell-substrate distances have been achieved. The physical principles, including assay sensitivity and selectivity, are discussed in the context of cellular pathways of cell adhesion and migration. With the miniaturization of these types of sensors, cell migration and adhesion measurements in combination with specific fluorescent assays might thus deliver a high-content platform for drug development.
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Affiliation(s)
- Thomas S Hug
- Actuators and Microsystems Laboratory, Institute of Microtechnology, University of Neuchâtel, Neuchâtel, Switzerland.
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Abstract
Some periodontal pathogens disrupt epithelial barriers and cellular adhesion to the extracellular matrix, which affects the cytoskeleton. Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans exploit the cytoskeleton during their uptake by epithelial cells. Treponema denticola perturbs actin and actin-regulating pathways in host cells. Cytoskeletal dysfunction due to pathogenic bacteria may impair physiologic remodeling and wound repair in the periodontium.
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Affiliation(s)
- R P Ellen
- University of Toronto, Faculty of Dentistry, 124 Edward Street, Toronto M5G 1G6, Canada
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Battikhi T, Lee W, McCulloch CA, Ellen RP. Treponema denticola outer membrane enhances the phagocytosis of collagen-coated beads by gingival fibroblasts. Infect Immun 1999; 67:1220-6. [PMID: 10024564 PMCID: PMC96450 DOI: 10.1128/iai.67.3.1220-1226.1999] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human gingival fibroblasts (HGFs) degrade collagen fibrils in physiological processes by phagocytosis. Since Treponema denticola outer membrane (OM) extract perturbs actin filaments, important structures in phagocytosis, we determined whether the OM affects collagen phagocytosis in vitro by HGFs. Phagocytosis was measured by flow cytometric assessment of internalized collagen-coated fluorescent latex beads. Confluent HGFs pretreated with T. denticola ATCC 35405 OM exhibited an increase in the percentage of collagen phagocytic cells (phagocytosis index [PI]) and in the number of beads per phagocytosing cell (phagocytic capacity [PC]) compared with untreated controls. The enhancement was swift (within 15 min) and was still evident after 1 day. PI and PC of HGFs for bovine serum albumin (BSA)-coated beads were also increased, indicating a global increase in phagocytic processes. These results contrasted those for control OM from Veillonella atypica ATCC 17744, which decreased phagocytosis. The T. denticola OM-induced increase in bead uptake was eliminated by heating the OM and by depolymerization of actin filaments by cytochalasin D treatment of HGFs. Fluid-phase accumulation of lucifer yellow was enhanced in a saturable, concentration-dependent, transient manner by the T. denticola OM. Our findings were not due to HGF detachment or cytotoxicity in response to the T. denticola OM treatment since the HGFs exhibited minimal detachment from the substratum; they did not take up propidium iodide; and there was no change in their size, granularity, or content of sub-G1 DNA. We conclude that a heat-sensitive component(s) in T. denticola OM extract stimulates collagen phagocytosis and other endocytic processes such as nonspecific phagocytosis and pinocytosis by HGFs.
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Affiliation(s)
- T Battikhi
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada M5G 1G6
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