851
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Blakely JT, Gordon R, Sinton D. Flow-dependent optofluidic particle trapping and circulation. LAB ON A CHIP 2008; 8:1350-6. [PMID: 18651078 DOI: 10.1039/b805318a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Microfluidics and fiber optics are integrated in-plane to achieve several flow-dependent particle trapping mechanisms on-chip. Each mechanism results from a combination of fluid drag and optical scattering forces. Parallel and offset fibers, orthogonally oriented to the flow, show cyclic cross-stream particle transit with flow-dependent particle trajectories and loss. Upstream-angled fibers with flow result in circulatory particle trajectories. Asymmetric angled fibers result in continuous particle circulation whereas symmetry with respect to the flow axis enables both stable trapping and circulation modes. Stable trapping of single particles, self-guided multi-particle arrays and particle assemblies are demonstrated with a single upstream-oriented fiber. Size tuning of trapped multiple particle assemblies is also presented. The planar interaction of fluid drag and optical forces results in novel possibilities for cost-effective on-chip diagnostics, mixing, flow rate monitoring, and cell analysis.
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Affiliation(s)
- J Thomas Blakely
- Department Electrical and Computer Engineering, University of Victoria, BC, CanadaV8W 3P6
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852
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Kim YC, Park SJ, Park JK. Biomechanical analysis of cancerous and normal cells based on bulge generation in a microfluidic device. Analyst 2008; 133:1432-9. [PMID: 18810292 DOI: 10.1039/b805355c] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This paper presents a new biomechanical analysis method for discrimination between cancerous and normal cells through compression by poly(dimethylsiloxane) (PDMS) membrane deflection in a microfluidic device. When a cell is compressed, cellular membrane will expand and then small bulges will appear on the peripheral cell membrane beyond the allowable strain. It is well known that the amount of F-actin in cancer cells is less than that of normal cells and bulges occur at the sites where cytoskeleton becomes detached from the membrane bilayer. Accordingly, we have demonstrated the difference of the bulge generation between breast cancer cells (MCF7) and normal cells (MCF10A). After excessive deformation, the bulges generated in MCF7 cells were not evenly distributed on the cell periphery. Contrary to this, the bulges of MCF10A cells showed an even distribution. In addition, the morphologies of bulges of MCF7 and MCF10A cells looked swollen protrusion and tubular protrusion, respectively. Peripheral strains at the moment of the bulge generation were also 72% in MCF7 and 46% in MCF10A. The results show that the bulge generation can be correlated with the cytoskeleton quantity inside the cell, providing the first step of a new biomechanical approach.
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Affiliation(s)
- Yu Chang Kim
- Department of Bio and Brain Engineering, KAIST, 335 Gwahangno, Yuseong-gu, Daejeon 305-701, Korea
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853
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Zhang H, Liu KK. Optical tweezers for single cells. J R Soc Interface 2008; 5:671-90. [PMID: 18381254 PMCID: PMC2408388 DOI: 10.1098/rsif.2008.0052] [Citation(s) in RCA: 366] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2008] [Revised: 03/17/2008] [Accepted: 03/17/2008] [Indexed: 11/12/2022] Open
Abstract
Optical tweezers (OT) have emerged as an essential tool for manipulating single biological cells and performing sophisticated biophysical/biomechanical characterizations. Distinct advantages of using tweezers for these characterizations include non-contact force for cell manipulation, force resolution as accurate as 100aN and amiability to liquid medium environments. Their wide range of applications, such as transporting foreign materials into single cells, delivering cells to specific locations and sorting cells in microfluidic systems, are reviewed in this article. Recent developments of OT for nanomechanical characterization of various biological cells are discussed in terms of both their theoretical and experimental advancements. The future trends of employing OT in single cells, especially in stem cell delivery, tissue engineering and regenerative medicine, are prospected. More importantly, current limitations and future challenges of OT for these new paradigms are also highlighted in this review.
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Affiliation(s)
| | - Kuo-Kang Liu
- Institute for Science and Technology in Medicine, Keele UniversityStoke-on-Trent ST4 7QB, UK
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854
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Reed J, Frank M, Troke JJ, Schmit J, Han S, Teitell MA, Gimzewski JK. High throughput cell nanomechanics with mechanical imaging interferometry. NANOTECHNOLOGY 2008; 19:235101. [PMID: 20737027 PMCID: PMC2925287 DOI: 10.1088/0957-4484/19/23/235101] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The dynamic nanomechanical properties of a large number of cells (up to hundreds), measured in parallel with high throughput, are reported. Using NIH 3T3 and HEK 293T fibroblasts and actin depolymerizing drugs, we use a novel nanotechnology to quantify the local viscoelastic properties with applied forces of 20 pN-20 nN, a spatial resolution of <20 nm, and a mechanical dynamic range of several Pa up to ~200 kPa. Our approach utilizes imaging interferometry in combination with reflective, magnetic probes attached to cells. These results indicate that mechanical imaging interferometry is a sensitive and scalable technology for measuring the nanomechanical properties of large arrays of live cells in fluid.
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Affiliation(s)
- Jason Reed
- Department of Chemistry and Biochemistry, UCLA, 607 Charles Young Drive East, Los Angeles, CA 90095, USA
- California NanoSystems Institute (CNSI), 570 Westwood Plaza, Los Angeles, CA 90095, USA
| | - Matthew Frank
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, Los Angeles, CA 90095-1732, USA
| | - Joshua J Troke
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, Los Angeles, CA 90095-1732, USA
| | - Joanna Schmit
- Veeco Instruments, Inc., 2650 E. Elvira Road, Tucson, AZ 85711, USA
| | - Sen Han
- Veeco Instruments, Inc., 2650 E. Elvira Road, Tucson, AZ 85711, USA
| | - Michael A Teitell
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, Los Angeles, CA 90095-1732, USA
- California NanoSystems Institute (CNSI), 570 Westwood Plaza, Los Angeles, CA 90095, USA
- Jonsson Comprehensive Cancer Center, Institute for Stem Cell Biology and Medicine (ISCBM), and Molecular Biology Institute, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, Los Angeles, CA 90095-1732, USA
| | - James K Gimzewski
- Department of Chemistry and Biochemistry, UCLA, 607 Charles Young Drive East, Los Angeles, CA 90095, USA
- California NanoSystems Institute (CNSI), 570 Westwood Plaza, Los Angeles, CA 90095, USA
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855
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Ma Z, Burg KJL, Wei Y, Yuan XC, Peng X, Gao BZ. Laser-guidance based detection of cells with single-gene modification. APPLIED PHYSICS LETTERS 2008; 92:213902-2139023. [PMID: 19479045 PMCID: PMC2682740 DOI: 10.1063/1.2938020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2008] [Accepted: 05/06/2008] [Indexed: 05/27/2023]
Abstract
An optical method with single-gene sensitivity for cell detection based on laser guidance was explored. Guided by the optical force from a weakly focused laser beam, a cell will move along the laser axis. Cells with different properties experience different optical forces and thus guidance speeds. The guidance speeds of the TC-1 cell and its genetically modified counterpart with only one gene change, L-10 cell, were studied under the same conditions. The results demonstrated that this laser guidance-based speed-measurement method can precisely distinguish cells that differ by only one gene.
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856
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Elasticity measurement of living cells with an atomic force microscope: data acquisition and processing. Pflugers Arch 2008; 457:551-9. [DOI: 10.1007/s00424-008-0524-3] [Citation(s) in RCA: 172] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2008] [Accepted: 04/22/2008] [Indexed: 01/19/2023]
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857
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Weiss M. Probing the Interior of Living Cells with Fluorescence Correlation Spectroscopy. Ann N Y Acad Sci 2008; 1130:21-7. [DOI: 10.1196/annals.1430.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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858
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Abstract
The primary cause of cancer treatment failure is invasion and metastasis, and invading tumor cells utilize many of the motility patterns that have been documented for normal morphogenesis. Recently, the role of mechanical forces in guiding various tissue and cell movements in embryonic development has been systematically analyzed with new experimental and computational methods. The tissue and cellular mechanobiology approach also holds promise for increasing the understanding of tumor invasion. In fact, the mechanical stiffness of tumors has correlated with invasiveness, and manipulation of extracellular matrix (ECM) stiffness in vitro has suppressed the cancer phenotype. Several important signaling molecules reside on the cytoskeleton, which is affected by external stress imparted by the ECM, and deformation of the nucleus can trigger the activation of certain genes. All these observations suggest that a synthesis of the biology of cancer cell invasion and cellular mechanobiology may offer new targets for the treatment of malignant disease. Accordingly, sensitive and relevant in vivo models and methods to study cancer mechanobiology are needed.
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Affiliation(s)
- Milan Makale
- Moores UCSD Cancer Center, University of California, San Diego, La Jolla, California 92093-0819, USA.
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859
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Fontes A, Fernandes HP, de Thomaz AA, Barbosa LC, Barjas-Castro ML, Cesar CL. Measuring electrical and mechanical properties of red blood cells with double optical tweezers. JOURNAL OF BIOMEDICAL OPTICS 2008; 13:014001. [PMID: 18315359 DOI: 10.1117/1.2870108] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Red blood cell (RBC) aggregation in the blood stream is prevented by the zeta potential created by its negatively charged membrane. There are techniques, however, to decrease the zeta potential and allow cell agglutination, which are the basis of most of antigen-antibody tests used in immunohematology. We propose the use of optical tweezers to measure membrane viscosity, adhesion, zeta potential, and the double layer thickness of charges (DLT) formed around the cell in an electrolytic solution. For the membrane viscosity experiment, we trap a bead attached to RBCs and measure the force to slide one RBC over the other as a function of the velocity. Adhesion is quantified by displacing two RBCs apart until disagglutination. The DLT is measured using the force on the bead attached to a single RBC in response to an applied voltage. The zeta potential is obtained by measuring the terminal velocity after releasing the RBC from the trap at the last applied voltage. We believe that the methodology proposed here can provide information about agglutination, help to improve the tests usually performed in transfusion services, and be applied for zeta potential measurements in other samples.
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Affiliation(s)
- Adriana Fontes
- Universidade Federal de Pernambuco, Cidade Universitária, Departamento de Biofísica e Radiobiologia, Av. Professor Moraes Rego, 50670-901, Recife-PE, Brasil.
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860
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Faria EC, Ma N, Gazi E, Gardner P, Brown M, Clarke NW, Snook RD. Measurement of elastic properties of prostate cancer cells using AFM. Analyst 2008; 133:1498-500. [DOI: 10.1039/b803355b] [Citation(s) in RCA: 204] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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861
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Lele TP, Kumar S. Brushes, cables, and anchors: recent insights into multiscale assembly and mechanics of cellular structural networks. Cell Biochem Biophys 2007; 47:348-60. [PMID: 17652780 DOI: 10.1007/s12013-007-0013-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/1999] [Revised: 11/30/1999] [Accepted: 11/30/1999] [Indexed: 01/09/2023]
Abstract
The remarkable ability of living cells to sense, process, and respond to mechanical stimuli in their environment depends on the rapid and efficient interconversion of mechanical and chemical energy at specific times and places within the cell. For example, application of force to cells leads to conformational changes in specific mechanosensitive molecules which then trigger cellular signaling cascades that may alter cellular structure, mechanics, and migration and profoundly influence gene expression. Similarly, the sensitivity of cells to mechanical stresses is governed by the composition, architecture, and mechanics of the cellular cytoskeleton and extracellular matrix (ECM), which are in turn driven by molecular-scale forces between the constituent biopolymers. Understanding how these mechanochemical systems coordinate over multiple length and time scales to produce orchestrated cell behaviors represents a fundamental challenge in cell biology. Here, we review recent advances in our understanding of these complex processes in three experimental systems: the assembly of axonal neurofilaments, generation of tensile forces by actomyosin stress fiber bundles, and mechanical control of adhesion assembly.
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Affiliation(s)
- Tanmay P Lele
- Department of Chemical Engineering, University of Florida, Gainesville, FL, USA
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862
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Abstract
The unique mechanical performance of animal cells and tissues is attributed mostly to their internal biopolymer meshworks. Its perplexing universality and robustness against structural modifications by drugs and mutations is an enigma in cell biology and provides formidable challenges to materials science. Recent investigations could pinpoint highly universal patterns in the soft glassy rheology and nonlinear elasticity of cells and reconstituted networks. Here, we report observations of a glass transition in semidilute F-actin solutions, which could hold the key to a unified explanation of these phenomena. Combining suitable rheological protocols with high-precision dynamic light scattering, we can establish a remarkable rheological redundancy and trace it back to a highly universal exponential stretching of the single-polymer relaxation spectrum of a "glassy wormlike chain." By exploiting the ensuing generalized time-temperature superposition principle, the time domain accessible to microrheometry can be extended by several orders of magnitude, thus opening promising new metrological opportunities.
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863
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An historical perspective on cell mechanics. Pflugers Arch 2007; 456:3-12. [DOI: 10.1007/s00424-007-0405-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2007] [Revised: 11/12/2007] [Accepted: 11/15/2007] [Indexed: 11/26/2022]
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864
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Cross SE, Jin YS, Rao J, Gimzewski JK. Nanomechanical analysis of cells from cancer patients. NATURE NANOTECHNOLOGY 2007; 2:780-3. [PMID: 18654431 DOI: 10.1038/nnano.2007.388] [Citation(s) in RCA: 1168] [Impact Index Per Article: 68.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2007] [Accepted: 10/19/2007] [Indexed: 05/20/2023]
Abstract
Change in cell stiffness is a new characteristic of cancer cells that affects the way they spread. Despite several studies on architectural changes in cultured cell lines, no ex vivo mechanical analyses of cancer cells obtained from patients have been reported. Using atomic force microscopy, we report the stiffness of live metastatic cancer cells taken from the body (pleural) fluids of patients with suspected lung, breast and pancreas cancer. Within the same sample, we find that the cell stiffness of metastatic cancer cells is more than 70% softer, with a standard deviation over five times narrower, than the benign cells that line the body cavity. Different cancer types were found to display a common stiffness. Our work shows that mechanical analysis can distinguish cancerous cells from normal ones even when they show similar shapes. These results show that nanomechanical analysis correlates well with immunohistochemical testing currently used for detecting cancer.
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865
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866
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Weiss EC, Anastasiadis P, Pilarczyk G, Lemor RM, Zinin PV. Mechanical properties of single cells by high-frequency time-resolved acoustic microscopy. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2007; 54:2257-71. [PMID: 18051160 DOI: 10.1109/tuffc.2007.530] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
In this paper, we describe a new, high-frequency, time-resolved scanning acoustic microscope developed for studying dynamical processes in biological cells. The new acoustic microscope operates in a time-resolved mode. The center frequency is 0.86 GHz, and the pulse duration is 5 ns. With such a short pulse, layers thicker than 3 microm can be resolved. For a cell thicker than 3 microm, the front echo and the echo from the substrate can be distinguished in the signal. Positions of the first and second pulses are used to determine the local impedance of the cell modeled as a thin liquid layer that has spatial variations in its elastic properties. The low signal-to-noise ratio in the acoustical images is increased for image generation by averaging the detected radio frequency signal over 10 measurements at each scanning point. In conducting quantitative measurements of the acoustic parameters of cells, the signal can be averaged over 2000 measurements. This approach enables us to measure acoustical properties of a single HeLa cell in vivo and to derive elastic parameters of subcellular structures. The value of the sound velocity inside the cell (1534.5 +/- 33.6 m/s) appears to be only slightly higher than that of the cell medium (1501 m/s).
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Affiliation(s)
- Eike C Weiss
- Biomedical Ultrasound Research, Fraunhofer-Institute for Biomedical Technology, St. Ingbert, Germany
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867
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Lincoln B, Schinkinger S, Travis K, Wottawah F, Ebert S, Sauer F, Guck J. Reconfigurable microfluidic integration of a dual-beam laser trap with biomedical applications. Biomed Microdevices 2007; 9:703-10. [PMID: 17505883 DOI: 10.1007/s10544-007-9079-x] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A dual-beam fiber laser trap, termed the optical stretcher when used to deform objects, has been combined with a capillary-based microfluidic system in order to serially trap and deform biological cells. The design allows for control over the size and position of the trap relative to the flow channel. Data is recorded using video phase contrast microscopy and is subsequently analyzed using a custom edge fitting routine. This setup has been regularly used with measuring rates of 50-100 cells/h. One such experiment is presented to compare the distribution of deformability found within a normal epithelial cell line to that of a cancerous one. In general, this microfluidic optical stretcher can be used for the characterization of cells by their viscoelastic signature. Possible applications include the cytological diagnosis of cancer and the gentle and marker-free sorting of stem cells from heterogeneous populations for therapeutic cell-based approaches in regenerative medicine.
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Affiliation(s)
- Bryan Lincoln
- Institut für Experimentalphysik I, Universität Leipzig, Linnéstr. 5, 04103, Leipzig, Germany
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868
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Abstract
Forces are increasingly recognized as major regulators of cell structure and function, and the mechanical properties of cells are essential to the mechanisms by which cells sense forces, transmit them to the cell interior or to other cells, and transduce them into chemical signals that impact a spectrum of cellular responses. Comparison of the mechanical properties of intact cells with those of the purified cytoskeletal biopolymers that are thought to dominate their elasticity reveal the extent to which the studies of purified systems can account for the mechanical properties of the much more heterogeneous and complex cell. This review summarizes selected aspects of current work on cell mechanics with an emphasis on the structures that are activated in cell-cell contacts, that regulate ion flow across the plasma membrane, and that may sense fluid flow that produces low levels of shear stress.
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Affiliation(s)
- Paul A Janmey
- Department of Physiology, Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
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869
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Guigas G, Kalla C, Weiss M. The degree of macromolecular crowding in the cytoplasm and nucleoplasm of mammalian cells is conserved. FEBS Lett 2007; 581:5094-8. [DOI: 10.1016/j.febslet.2007.09.054] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Revised: 09/14/2007] [Accepted: 09/24/2007] [Indexed: 10/22/2022]
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870
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Hunt HC, Wilkinson JS. Optofluidic integration for microanalysis. MICROFLUIDICS AND NANOFLUIDICS 2007; 4:53-79. [PMID: 32214954 PMCID: PMC7087941 DOI: 10.1007/s10404-007-0223-y] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2007] [Accepted: 07/25/2007] [Indexed: 05/09/2023]
Abstract
This review describes recent research in the application of optical techniques to microfluidic systems for chemical and biochemical analysis. The "lab-on-a-chip" presents great benefits in terms of reagent and sample consumption, speed, precision, and automation of analysis, and thus cost and ease of use, resulting in rapidly escalating adoption of microfluidic approaches. The use of light for detection of particles and chemical species within these systems is widespread because of the sensitivity and specificity which can be achieved, and optical trapping, manipulation and sorting of particles show significant benefits in terms of discrimination and reconfigurability. Nonetheless, the full integration of optical functions within microfluidic chips is in its infancy, and this review aims to highlight approaches, which may contribute to further miniaturisation and integration.
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Affiliation(s)
- Hamish C. Hunt
- Optoelectronics Research Centre, University of Southampton, Highfield, Southampton, Hampshire SO17 1BJ UK
| | - James S. Wilkinson
- Optoelectronics Research Centre, University of Southampton, Highfield, Southampton, Hampshire SO17 1BJ UK
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871
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Darling EM, Topel M, Zauscher S, Vail TP, Guilak F. Viscoelastic properties of human mesenchymally-derived stem cells and primary osteoblasts, chondrocytes, and adipocytes. J Biomech 2007; 41:454-64. [PMID: 17825308 PMCID: PMC2897251 DOI: 10.1016/j.jbiomech.2007.06.019] [Citation(s) in RCA: 262] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2007] [Revised: 06/23/2007] [Accepted: 06/25/2007] [Indexed: 01/14/2023]
Abstract
The mechanical properties of single cells play important roles in regulating cell-matrix interactions, potentially influencing the process of mechanotransduction. Recent studies also suggest that cellular mechanical properties may provide novel biological markers, or "biomarkers," of cell phenotype, reflecting specific changes that occur with disease, differentiation, or cellular transformation. Of particular interest in recent years has been the identification of such biomarkers that can be used to determine specific phenotypic characteristics of stem cells that separate them from primary, differentiated cells. The goal of this study was to determine the elastic and viscoelastic properties of three primary cell types of mesenchymal lineage (chondrocytes, osteoblasts, and adipocytes) and to test the hypothesis that primary differentiated cells exhibit distinct mechanical properties compared to adult stem cells (adipose-derived or bone marrow-derived mesenchymal stem cells). In an adherent, spread configuration, chondrocytes, osteoblasts, and adipocytes all exhibited significantly different mechanical properties, with osteoblasts being stiffer than chondrocytes and both being stiffer than adipocytes. Adipose-derived and mesenchymal stem cells exhibited similar properties to each other, but were mechanically distinct from primary cells, particularly when comparing a ratio of elastic to relaxed moduli. These findings will help more accurately model the cellular mechanical environment in mesenchymal tissues, which could assist in describing injury thresholds and disease progression or even determining the influence of mechanical loading for tissue engineering efforts. Furthermore, the identification of mechanical properties distinct to stem cells could result in more successful sorting procedures to enrich multipotent progenitor cell populations.
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Affiliation(s)
- Eric M. Darling
- Department of Surgery, Duke University Medical Center, Durham, NC 27710 USA
- Department of Biomedical Engineering, Duke University Medical Center, Durham, NC 27710 USA
| | - Matthew Topel
- Department of Biomedical Engineering, Duke University Medical Center, Durham, NC 27710 USA
| | - Stefan Zauscher
- Department of Mechanical Engineering & Materials Science, Duke University Medical Center, Durham, NC 27710 USA
| | - Thomas P. Vail
- Department of Surgery, Duke University Medical Center, Durham, NC 27710 USA
| | - Farshid Guilak
- Department of Surgery, Duke University Medical Center, Durham, NC 27710 USA
- Department of Biomedical Engineering, Duke University Medical Center, Durham, NC 27710 USA
- Department of Mechanical Engineering & Materials Science, Duke University Medical Center, Durham, NC 27710 USA
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872
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Lincoln B, Wottawah F, Schinkinger S, Ebert S, Guck J. High-throughput rheological measurements with an optical stretcher. Methods Cell Biol 2007; 83:397-423. [PMID: 17613318 DOI: 10.1016/s0091-679x(07)83017-2] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The cytoskeleton is a major determinant of the mechanical strength and morphology of most cells. The composition and assembly state of this intracellular polymer network evolve during the differentiation of cells, and the structure is involved in many cellular functions and is characteristically altered in many diseases, including cancer. Here we exploit the deformability of the cytoskeleton as a link between molecular structure and biological function, to distinguish between cells in different states by using a laser-based optical stretcher (OS) coupled with microfluidic handling of cells. An OS is a cell-sized, dual-beam laser trap designed to nondestructively test the deformability of single suspended cells. Combined with microfluidic delivery, many cells can be measured serially in a short amount of time. With this tool it could be shown that optical deformability is sensitive enough to monitor subtle changes during the progression of cells from normal to cancerous and even a metastatic state. Stem cells can also be distinguished from more differentiated cells. The surprisingly low number of cells required for this assay reflects the tight regulation of the cytoskeleton by the cell. This suggests the possibility of using optical deformability as an inherent cell marker for basic cell biological investigation, diagnosis of disease, and sorting of stem cells from heterogeneous populations, obviating the need for external markers or special preparation. Many additional biological assays can be easily adapted to utilize this innovative physical method. This chapter details the setup and use of the microfluidic OS, the analysis and interpretation of data, and the results of a typical experiment.
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Affiliation(s)
- Bryan Lincoln
- Institut für Experimentelle Physik I, Universität Leipzig, Linnéstrasse 5, 04103 Leipzig, Germany
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873
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Smith RL, Spalding GC, Dholakia K, MacDonald MP. Colloidal sorting in dynamic optical lattices. ACTA ACUST UNITED AC 2007. [DOI: 10.1088/1464-4258/9/8/s05] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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874
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Abstract
The past decade has seen substantial growth in research into how changes in the biomechanical and biophysical properties of cells and subcellular structures influence, and are influenced by, the onset and progression of human diseases. This paper presents an overview of the rapidly expanding, nascent field of research that deals with the biomechanics and biophysics of cancer cells. The review begins with some key observations on the biology of cancer cells and on the role of actin microfilaments, intermediate filaments and microtubule biopolymer cytoskeletal components in influencing cell mechanics, locomotion, differentiation and neoplastic transformation. In order to set the scene for mechanistic discussions of the connections among alterations to subcellular structures, attendant changes in cell deformability, cytoadherence, migration, invasion and tumor metastasis, a survey is presented of the various quantitative mechanical and physical assays to extract the elastic and viscoelastic deformability of cancer cells. Results available in the literature on cell mechanics for different types of cancer are then reviewed. Representative case studies are presented next to illustrate how chemically induced cytoskeletal changes, biomechanical responses and signals from the intracellular regions act in concert with the chemomechanical environment of the extracellular matrix and the molecular tumorigenic signaling pathways to effect malignant transformations. Results are presented to illustrate how changes to cytoskeletal architecture induced by cancer drugs and chemotherapy regimens can significantly influence cell mechanics and disease state. It is reasoned through experimental evidence that greater understanding of the mechanics of cancer cell deformability and its interactions with the extracellular physical, chemical and biological environments offers enormous potential for significant new developments in disease diagnostics, prophylactics, therapeutics and drug efficacy assays.
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Affiliation(s)
- Subra Suresh
- Department of Materials Science and Engineering, Division of Biological Engineering, and Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139-4307, USA.
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875
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Lee GYH, Lim CT. Biomechanics approaches to studying human diseases. Trends Biotechnol 2007; 25:111-8. [PMID: 17257698 DOI: 10.1016/j.tibtech.2007.01.005] [Citation(s) in RCA: 278] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2006] [Accepted: 01/12/2007] [Indexed: 01/09/2023]
Abstract
Nanobiomechanics has recently been identified as an emerging field that can potentially make significant contributions in the study of human diseases. Research into biomechanics at the cellular and molecular levels of some human diseases has not only led to a better elucidation of the mechanisms behind disease progression, because diseased cells differ physically from healthy ones, but has also provided important knowledge in the fight against these diseases. This article highlights some of the cell and molecular biomechanics research carried out on human diseases such as malaria, sickle cell anemia and cancer and aims to provide further important insights into the pathophysiology of such diseases. It is hoped that this can lead to new methods of early detection, diagnosis and treatment.
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Affiliation(s)
- Gabriel Y H Lee
- Singapore-MIT Alliance, 4 Engineering Drive 3, Singapore 117576, Singapore
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876
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Schulz RM, Bader A. Cartilage tissue engineering and bioreactor systems for the cultivation and stimulation of chondrocytes. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2007; 36:539-68. [PMID: 17318529 DOI: 10.1007/s00249-007-0139-1] [Citation(s) in RCA: 156] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2006] [Revised: 01/23/2007] [Accepted: 01/29/2007] [Indexed: 12/14/2022]
Abstract
Damage to and degeneration of articular cartilage is a major health issue in industrialized nations. Articular cartilage has a particularly limited capacity for auto regeneration. At present, there is no established therapy for a sufficiently reliable and durable replacement of damaged articular cartilage. In this, as well as in other areas of regenerative medicine, tissue engineering methods are considered to be a promising therapeutic component. Nevertheless, there remain obstacles to the establishment of tissue-engineered cartilage as a part of the routine therapy for cartilage defects. One necessary aspect of potential tissue engineering-based therapies for cartilage damage that requires both elucidation and progress toward practical solutions is the reliable, cost effective cultivation of suitable tissue. Bioreactors and associated methods and equipment are the tools with which it is hoped that such a supply of tissue-engineered cartilage can be provided. The fact that in vivo adaptive physical stimulation influences chondrocyte function by affecting mechanotransduction leads to the development of specifically designed bioreactor devices that transmit forces like shear, hydrostatic pressure, compression, and combinations thereof to articular and artificial cartilage in vitro. This review summarizes the basic knowledge of chondrocyte biology and cartilage dynamics together with the exploration of the various biophysical principles of cause and effect that have been integrated into bioreactor systems for the cultivation and stimulation of chondrocytes.
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Affiliation(s)
- Ronny Maik Schulz
- Department of Cell Techniques and Applied Stem Cell Biology, Center of Biotechnology and Biomedicine, University of Leipzig, Leipzig, Germany.
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877
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Girard PP, Cavalcanti-Adam EA, Kemkemer R, Spatz JP. Cellular chemomechanics at interfaces: sensing, integration and response. SOFT MATTER 2007; 3:307-326. [PMID: 32900147 DOI: 10.1039/b614008d] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Living cells are complex entities whose remarkable, emergent capacity to sense, integrate, and respond to environmental cues relies on an intricate series of interactions among the cell's macromolecular components. Defects in mechanosensing, transduction,or responses underlie many diseases such as cancers, immune disorders, cardiac hypertrophy, genetic malformations, and neuropathies. Here, we highlight micro- and nanotechnology-based tools that have been used to study how chemical and mechanical cues modulate the responses of single cells in contact with the extracellular environment. Understanding the physical aspects of these complex processes at the micro- and nanometer scale could produce profound and fundamental new insights into how the processes of cell migration, metastasis, immune function and other areas which are regulated by mechanical forces.
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Affiliation(s)
- Philippe P Girard
- Max-Planck-Institute for Metals Research, Dept. New Materials and Biosystems, Heisenbergstr. 3, D-70569 Stuttgart, Germany and University of Heidelberg, Dept. Biophysical Chemistry, INF 253, D-69120 Heidelberg, Germany.
| | - Elisabetta A Cavalcanti-Adam
- Max-Planck-Institute for Metals Research, Dept. New Materials and Biosystems, Heisenbergstr. 3, D-70569 Stuttgart, Germany and University of Heidelberg, Dept. Biophysical Chemistry, INF 253, D-69120 Heidelberg, Germany.
| | - Ralf Kemkemer
- Max-Planck-Institute for Metals Research, Dept. New Materials and Biosystems, Heisenbergstr. 3, D-70569 Stuttgart, Germany and University of Heidelberg, Dept. Biophysical Chemistry, INF 253, D-69120 Heidelberg, Germany.
| | - Joachim P Spatz
- Max-Planck-Institute for Metals Research, Dept. New Materials and Biosystems, Heisenbergstr. 3, D-70569 Stuttgart, Germany and University of Heidelberg, Dept. Biophysical Chemistry, INF 253, D-69120 Heidelberg, Germany.
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878
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Whipple RA, Cheung AM, Martin SS. Detyrosinated microtubule protrusions in suspended mammary epithelial cells promote reattachment. Exp Cell Res 2007; 313:1326-36. [PMID: 17359970 PMCID: PMC3132414 DOI: 10.1016/j.yexcr.2007.02.001] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2006] [Revised: 01/31/2007] [Accepted: 02/01/2007] [Indexed: 11/17/2022]
Abstract
Breast tumor cells enter the bloodstream long before the development of clinically evident metastasis. However, the early presence of such bloodborne cells predicts poor patient outcome. Nearly 90% of human breast tumors arise as carcinomas from mammary epithelial cells, so it is important to study how these cells respond to the detached conditions that they would experience in the bloodstream. We report here that mammary epithelial cell lines produce long and dynamic protrusions of the plasma membrane when detached. Although human and mouse mammary epithelial cell lines die by apoptosis within 16 h of detachment, this protrusive response persists for days in cells overexpressing either Bcl-2 or Bcl-xL. Unlike actin-dependent invadopodia and podosomes, these protrusions are actually enhanced by actin depolymerization with Cytochalasin-D or Latrunculin-A. Immunofluorescence and Western blotting demonstrate that the protrusions are enriched in detyrosinated Glu-tubulin, a post-translationally modified form of alpha-tubulin that is found in stabilized microtubules. Video microscopy indicates that these protrusions promote cell-cell attachment, and inhibiting microtubule-based protrusions correlates with reduced extracellular matrix attachment. Since bloodborne metastasis depends on both cell-cell and cell-matrix attachment, microtubule-based protrusions in detached mammary epithelial cells provide a novel mechanism that could influence the metastatic spread of breast tumors.
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Affiliation(s)
- Rebecca A Whipple
- University of Maryland School of Medicine, Marlene and Stewart Greenebaum Cancer Center, Department of Physiology, Baltimore, MD 21201
| | - Agnes M. Cheung
- University of Maryland School of Medicine, Marlene and Stewart Greenebaum Cancer Center, Department of Physiology, Baltimore, MD 21201
| | - Stuart S. Martin
- University of Maryland School of Medicine, Marlene and Stewart Greenebaum Cancer Center, Department of Physiology, Baltimore, MD 21201
- Corresponding author: HSF-2, Rm S103C, 20 S. Penn St. Baltimore, MD 21201, Tel: 410-706-6601, Fax: 410-706-6600,
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879
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Darling EM, Zauscher S, Block JA, Guilak F. A thin-layer model for viscoelastic, stress-relaxation testing of cells using atomic force microscopy: do cell properties reflect metastatic potential? Biophys J 2006; 92:1784-91. [PMID: 17158567 PMCID: PMC1796808 DOI: 10.1529/biophysj.106.083097] [Citation(s) in RCA: 244] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Atomic force microscopy has rapidly become a valuable tool for quantifying the biophysical properties of single cells. The interpretation of atomic force microscopy-based indentation tests, however, is highly dependent on the use of an appropriate theoretical model of the testing configuration. In this study, a novel, thin-layer viscoelastic model for stress relaxation was developed to quantify the mechanical properties of chondrosarcoma cells in different configurations to examine the hypothesis that viscoelastic properties reflect the metastatic potential and invasiveness of the cell using three well-characterized human chondrosarcoma cell lines (JJ012, FS090, 105KC) that show increasing chondrocytic differentiation and decreasing malignancy, respectively. Single-cell stress relaxation tests were conducted at 2 h and 2 days after plating to determine cell mechanical properties in either spherical or spread morphologies and analyzed using the new theoretical model. At both time points, JJ012 cells had the lowest moduli of the cell lines examined, whereas FS090 typically had the highest. At 2 days, all cells showed an increase in stiffness and a decrease in apparent viscosity compared to the 2-h time point. Fluorescent labeling showed that the F-actin structure in spread cells was significantly different between FS090 cells and JJ012/105KC cells. Taken together with results of previous studies, these findings indicate that cell transformation and tumorigenicity are associated with a decrease in cell modulus and apparent viscosity, suggesting that cell mechanical properties may provide insight into the metastatic potential and invasiveness of a cell.
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Affiliation(s)
- Eric M Darling
- Department of Surgery, Duke University Medical Center, Durham, North Carolina, USA
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880
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Ananthakrishnan R, Guck J, Wottawah F, Schinkinger S, Lincoln B, Romeyke M, Moon T, Käs J. Quantifying the contribution of actin networks to the elastic strength of fibroblasts. J Theor Biol 2006; 242:502-16. [DOI: 10.1016/j.jtbi.2006.03.021] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2005] [Revised: 03/16/2006] [Accepted: 03/22/2006] [Indexed: 01/13/2023]
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881
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Zharov VP, Galanzha EI, Tuchin VV. In vivo photothermal flow cytometry: imaging and detection of individual cells in blood and lymph flow. J Cell Biochem 2006; 97:916-32. [PMID: 16408292 DOI: 10.1002/jcb.20766] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Flow cytometry is a well-established, powerful technique for studying cells in artificial flow in vitro. This review covers a new potential application of this technique for studying normal and abnormal cells in their native condition in blood or lymph flow in vivo. Specifically, the capabilities of the label-free photothermal (PT) technique for detecting and imaging cells in the microvessel network of rat mesentery are analyzed from the point of view of overcoming the problems of flow cytometry in vivo. These problems include, among others, the influences of light scattering and absorption in vessel walls and surrounding tissues, instability of cell velocity, and cells numbers and positions in a vessel's cross-section. The potential applications of this new approach in cell biochemistry and medicine are discussed, including molecular imaging; studying the metabolism and pathogenesis of many diseases at a cellular level; and monitoring and quantifying metastatic and apoptotic cells, and/or their responses to therapeutic interventions (e.g., drug or radiation), in natural biological environments.
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Affiliation(s)
- Vladimir P Zharov
- Philips Classic Laser Laboratories, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA.
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882
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Dittrich PS, Tachikawa K, Manz A. Micro Total Analysis Systems. Latest Advancements and Trends. Anal Chem 2006; 78:3887-908. [PMID: 16771530 DOI: 10.1021/ac0605602] [Citation(s) in RCA: 564] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Petra S Dittrich
- Institute for Analytical Sciences, Bunsen-Kirchhoff-Strasse 11, D-44139 Dortmund, Germany
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883
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Abstract
Viscoelastic changes of the lamellipodial actin cytoskeleton are a fundamental element of cell motility. Thus, the correlation between the local viscoelastic properties of the lamellipodium (including the transitional region to the cell body) and the speed of lamellipodial extension is studied for normal and malignantly transformed fibroblasts. Using our atomic force microscopy-based microrheology technique, we found different mechanical properties between the lamellipodia of malignantly transformed fibroblasts (H-ras transformed and SV-T2 fibroblasts) and normal fibroblasts (BALB 3T3 fibroblasts). The average elastic constants, K, in the leading edge of SV-T2 fibroblasts (0.48 +/- 0.51 kPa) and of H-ras transformed fibroblasts (0.42 +/- 0.35 kPa) are significantly lower than that of BALB 3T3 fibroblasts (1.01 +/- 0.40 kPa). The analysis of time-lapse phase contrast images shows that the decrease in the elastic constant, K, for malignantly transformed fibroblasts is correlated with the enhanced motility of the lamellipodium. The measured mean speeds are 6.1 +/- 4.5 microm/h for BALB 3T3 fibroblasts, 13.1 +/- 5.2 microm/h for SV-T2 fibroblasts, and 26.2 +/- 11.5 microm/h for H-ras fibroblasts. Furthermore, the elastic constant, K, increases toward the cell body in many instances which coincide with an increase in actin filament density toward the cell body. The correlation between the enhanced motility and the decrease in viscoelastic moduli supports the Elastic Brownian Ratchet model for driving lamellipodia extension.
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Affiliation(s)
- S Park
- Department of Physics, Texas Materials Institute, and Center for Nano and Molecular Science, University of Texas, Austin, Texas 78712, USA.
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884
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Drasdo D, Höhme S. A single-cell-based model of tumor growth in vitro: monolayers and spheroids. Phys Biol 2005; 2:133-47. [PMID: 16224119 DOI: 10.1088/1478-3975/2/3/001] [Citation(s) in RCA: 239] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
To what extent the growth dynamics of tumors is controlled by nutrients, biomechanical forces and other factors at different stages and in different environments is still largely unknown. Here we present a biophysical model to study the spatio-temporal growth dynamics of two-dimensional tumor monolayers and three-dimensional tumor spheroids as a complementary tool to in vitro experiments. Within our model each cell is represented as an individual object and parametrized by cell-biophysical and cell-kinetic parameters that can all be experimentally determined. Hence our modeling strategy allows us to study which mechanisms on the microscopic level of individual cells may affect the macroscopic properties of a growing tumor. We find the qualitative growth kinetics and patterns at early growth stages to be remarkably robust. Quantitative comparisons between computer simulations using our model and published experimental observations on monolayer cultures suggest a biomechanically-mediated form of growth inhibition during the experimentally observed transition from exponential to sub-exponential growth at sufficiently large tumor sizes. Our simulations show that the same transition during the growth of avascular tumor spheroids can be explained largely by the same mechanism. Glucose (or oxygen) depletion seems to determine mainly the size of the necrotic core but not the size of the tumor. We explore the consequences of the suggested biomechanical form of contact inhibition, in order to permit an experimental test of our model. Based on our findings we propose a phenomenological growth law in early expansion phases in which specific biological small-scale processes are subsumed in a small number of effective parameters.
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Affiliation(s)
- Dirk Drasdo
- Interdisciplinary Centre for Bioinformatics, University of Leipzig, Härtelstr. 16-18, D-04107 Leipzig, Germany.
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885
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Wottawah F, Schinkinger S, Lincoln B, Ebert S, Müller K, Sauer F, Travis K, Guck J. Characterizing single suspended cells by optorheology. Acta Biomater 2005; 1:263-71. [PMID: 16701805 DOI: 10.1016/j.actbio.2005.02.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2005] [Revised: 02/11/2005] [Accepted: 02/13/2005] [Indexed: 10/25/2022]
Abstract
The measurement of the mechanical properties of individual cells has received much attention in recent years. In this paper we describe the application of optically induced forces with an optical stretcher to perform step-stress experiments on individual suspended fibroblasts. The conversion from creep-compliance to frequency-dependent complex shear modulus reveals characteristic viscoelastic signatures of the underlying cytoskeleton and its dynamic molecular properties. Both normal and cancerous fibroblasts display a single stress relaxation time in the observed time and frequency space that can be related to the transient binding of actin crosslinking proteins. In addition, shear modulus and steady-state viscosity of the shell-like actin cortex as the main module resisting small deformations are extracted. These values in combination with insight into the cells' architecture are used to explain their different deformability. This difference can then be exploited to distinguish normal from cancerous cells. The nature of the optical stretcher as an optical trap allows easy incorporation in a microfluidic system with automatic trapping and alignment of the cells, and thus a high measurement throughput. This carries the potential for using the microfluidic optical stretcher to investigate cellular processes involving the cytoskeleton and to diagnose diseases related to cytoskeletal alterations.
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Affiliation(s)
- Falk Wottawah
- Institute for Soft Matter Physics, Department of Physics and Geosciences, University of Leipzig, Linnéstrasse 5, 04103 Leipzig, Germany
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