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Burchert JP, Frohn J, Rölleke U, Bruns H, Yu B, Gleber SC, Stange R, Busse M, Osterhoff M, Salditt T, Köster S. X-ray phase-contrast tomography of cells manipulated with an optical stretcher. JOURNAL OF SYNCHROTRON RADIATION 2024; 31:923-935. [PMID: 38861370 PMCID: PMC11226146 DOI: 10.1107/s1600577524003618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Accepted: 04/21/2024] [Indexed: 06/13/2024]
Abstract
X-rays can penetrate deeply into biological cells and thus allow for examination of their internal structures with high spatial resolution. In this study, X-ray phase-contrast imaging and tomography is combined with an X-ray-compatible optical stretcher and microfluidic sample delivery. Using this setup, individual cells can be kept in suspension while they are examined with the X-ray beam at a synchrotron. From the recorded holograms, 2D phase shift images that are proportional to the projected local electron density of the investigated cell can be calculated. From the tomographic reconstruction of multiple such projections the 3D electron density can be obtained. The cells can thus be studied in a hydrated or even living state, thus avoiding artifacts from freezing, drying or embedding, and can in principle also be subjected to different sample environments or mechanical strains. This combination of techniques is applied to living as well as fixed and stained NIH3T3 mouse fibroblasts and the effect of the beam energy on the phase shifts is investigated. Furthermore, a 3D algebraic reconstruction scheme and a dedicated mathematical description is used to follow the motion of the trapped cells in the optical stretcher for multiple rotations.
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Affiliation(s)
- Jan-Philipp Burchert
- Institute for X-ray PhysicsUniversity of GöttingenFriedrich-Hund-Platz 137077GöttingenGermany
- Cluster of Excellence Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells (MBExC)University of GöttingenGermany
| | - Jasper Frohn
- Institute for X-ray PhysicsUniversity of GöttingenFriedrich-Hund-Platz 137077GöttingenGermany
| | - Ulrike Rölleke
- Institute for X-ray PhysicsUniversity of GöttingenFriedrich-Hund-Platz 137077GöttingenGermany
| | - Hendrik Bruns
- Institute for X-ray PhysicsUniversity of GöttingenFriedrich-Hund-Platz 137077GöttingenGermany
| | - Boram Yu
- Institute for X-ray PhysicsUniversity of GöttingenFriedrich-Hund-Platz 137077GöttingenGermany
| | - Sophie-Charlotte Gleber
- Institute for X-ray PhysicsUniversity of GöttingenFriedrich-Hund-Platz 137077GöttingenGermany
| | | | - Madleen Busse
- Biomedical Physics, School of ScienceTechnical University MunichBoltzmannstraße 1185748GarchingGermany
- Munich Institute of Biomedical EngineeringTechnical University MunichBoltzmannstraße 1185748GarchingGermany
| | - Markus Osterhoff
- Institute for X-ray PhysicsUniversity of GöttingenFriedrich-Hund-Platz 137077GöttingenGermany
| | - Tim Salditt
- Institute for X-ray PhysicsUniversity of GöttingenFriedrich-Hund-Platz 137077GöttingenGermany
- Cluster of Excellence Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells (MBExC)University of GöttingenGermany
| | - Sarah Köster
- Institute for X-ray PhysicsUniversity of GöttingenFriedrich-Hund-Platz 137077GöttingenGermany
- Cluster of Excellence Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells (MBExC)University of GöttingenGermany
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Stolz M. The Revolution in Breast Cancer Diagnostics: From Visual Inspection of Histopathology Slides to Using Desktop Tissue Analysers for Automated Nanomechanical Profiling of Tumours. Bioengineering (Basel) 2024; 11:237. [PMID: 38534510 DOI: 10.3390/bioengineering11030237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 02/26/2024] [Accepted: 02/27/2024] [Indexed: 03/28/2024] Open
Abstract
We aim to develop new portable desktop tissue analysers (DTAs) to provide fast, low-cost, and precise test results for fast nanomechanical profiling of tumours. This paper will explain the reasoning for choosing indentation-type atomic force microscopy (IT-AFM) to reveal the functional details of cancer. Determining the subtype, cancer stage, and prognosis will be possible, which aids in choosing the best treatment. DTAs are based on fast IT-AFM at the size of a small box that can be made for a low budget compared to other clinical imaging tools. The DTAs can work in remote areas and all parts of the world. There are a number of direct benefits: First, it is no longer needed to wait a week for the pathology report as the test will only take 10 min. Second, it avoids the complicated steps of making histopathology slides and saves costs of labour. Third, computers and robots are more consistent, more reliable, and more economical than human workers which may result in fewer diagnostic errors. Fourth, the IT-AFM analysis is capable of distinguishing between various cancer subtypes. Fifth, the IT-AFM analysis could reveal new insights about why immunotherapy fails. Sixth, IT-AFM may provide new insights into the neoadjuvant treatment response. Seventh, the healthcare system saves money by reducing diagnostic backlogs. Eighth, the results are stored on a central server and can be accessed to develop strategies to prevent cancer. To bring the IT-AFM technology from the bench to the operation theatre, a fast IT-AFM sensor needs to be developed and integrated into the DTAs.
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Affiliation(s)
- Martin Stolz
- National Centre for Advanced Tribology at Southampton, Faculty of Engineering and Physical Sciences, University of Southampton, Southampton SO17 1BJ, UK
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3
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Pesen T, Haydaroglu M, Capar S, Parlatan U, Unlu MB. Comparison of the human's and camel's red blood cell deformability by optical tweezers and Raman spectroscopy. Biochem Biophys Rep 2023; 35:101490. [PMID: 37664525 PMCID: PMC10474369 DOI: 10.1016/j.bbrep.2023.101490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 05/09/2023] [Accepted: 05/21/2023] [Indexed: 09/05/2023] Open
Abstract
Red blood cells of vertebrates have undergone evolutionary changes over time, leading to the diversification of morphological and mechanical properties of red blood cells (RBCs). Among the vertebrates, camelids have the most different RBC characteristics. As a result of adaptation to the desert environment, camelid RBCs can expand twice as much of their total volume in the case of rapid hydration yet are almost undeformable under mechanical stress. In this work, the mechanical and chemical differences in the RBC properties of the human and camelid species were examined using optical tweezers and Raman spectroscopy. We measured the deformability of camel and human RBCs at the single-cell level using optical tweezers. We found that the deformability index (DI) of the camel and the human RBCs were 0.024 ± 0.019 and 0.215 ± 0.061, respectively. To investigate the chemical properties of these cells, we measured the Raman spectra of the whole blood samples. The result of our study indicated that some of the Raman peaks observed on the camel's blood spectrum were absent in the human blood's spectrum, which further points to the difference in chemical contents of these two species' RBCs.
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Affiliation(s)
- Tuna Pesen
- Bogazici University, Department of Physics, Istanbul, 34470, Turkiye
| | - Mete Haydaroglu
- Bogazici University, Department of Physics, Istanbul, 34470, Turkiye
| | - Simal Capar
- Bogazici University, Department of Physics, Istanbul, 34470, Turkiye
| | - Ugur Parlatan
- Bogazici University, Department of Physics, Istanbul, 34470, Turkiye
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Salipante PF. Microfluidic techniques for mechanical measurements of biological samples. BIOPHYSICS REVIEWS 2023; 4:011303. [PMID: 38505816 PMCID: PMC10903441 DOI: 10.1063/5.0130762] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 12/30/2022] [Indexed: 03/21/2024]
Abstract
The use of microfluidics to make mechanical property measurements is increasingly common. Fabrication of microfluidic devices has enabled various types of flow control and sensor integration at micrometer length scales to interrogate biological materials. For rheological measurements of biofluids, the small length scales are well suited to reach high rates, and measurements can be made on droplet-sized samples. The control of flow fields, constrictions, and external fields can be used in microfluidics to make mechanical measurements of individual bioparticle properties, often at high sampling rates for high-throughput measurements. Microfluidics also enables the measurement of bio-surfaces, such as the elasticity and permeability properties of layers of cells cultured in microfluidic devices. Recent progress on these topics is reviewed, and future directions are discussed.
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Affiliation(s)
- Paul F. Salipante
- National Institute of Standards and Technology, Polymers and Complex Fluids Group, Gaithersburg, Maryland 20899, USA
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5
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Caveolin-1 dolines form a distinct and rapid caveolae-independent mechanoadaptation system. Nat Cell Biol 2023; 25:120-133. [PMID: 36543981 PMCID: PMC9859760 DOI: 10.1038/s41556-022-01034-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 10/21/2022] [Indexed: 12/24/2022]
Abstract
In response to different types and intensities of mechanical force, cells modulate their physical properties and adapt their plasma membrane (PM). Caveolae are PM nano-invaginations that contribute to mechanoadaptation, buffering tension changes. However, whether core caveolar proteins contribute to PM tension accommodation independently from the caveolar assembly is unknown. Here we provide experimental and computational evidence supporting that caveolin-1 confers deformability and mechanoprotection independently from caveolae, through modulation of PM curvature. Freeze-fracture electron microscopy reveals that caveolin-1 stabilizes non-caveolar invaginations-dolines-capable of responding to low-medium mechanical forces, impacting downstream mechanotransduction and conferring mechanoprotection to cells devoid of caveolae. Upon cavin-1/PTRF binding, doline size is restricted and membrane buffering is limited to relatively high forces, capable of flattening caveolae. Thus, caveolae and dolines constitute two distinct albeit complementary components of a buffering system that allows cells to adapt efficiently to a broad range of mechanical stimuli.
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Bashir KMI, Lee S, Jung DH, Basu SK, Cho MG, Wierschem A. Narrow-Gap Rheometry: A Novel Method for Measuring Cell Mechanics. Cells 2022; 11:cells11132010. [PMID: 35805094 PMCID: PMC9265971 DOI: 10.3390/cells11132010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 06/21/2022] [Accepted: 06/21/2022] [Indexed: 12/18/2022] Open
Abstract
The viscoelastic properties of a cell cytoskeleton contain abundant information about the state of a cell. Cells show a response to a specific environment or an administered drug through changes in their viscoelastic properties. Studies of single cells have shown that chemical agents that interact with the cytoskeleton can alter mechanical cell properties and suppress mitosis. This envisions using rheological measurements as a non-specific tool for drug development, the pharmacological screening of new drug agents, and to optimize dosage. Although there exists a number of sophisticated methods for studying mechanical properties of single cells, studying concentration dependencies is difficult and cumbersome with these methods: large cell-to-cell variations demand high repetition rates to obtain statistically significant data. Furthermore, method-induced changes in the cell mechanics cannot be excluded when working in a nonlinear viscoelastic range. To address these issues, we not only compared narrow-gap rheometry with commonly used single cell techniques, such as atomic force microscopy and microfluidic-based approaches, but we also compared existing cell monolayer studies used to estimate cell mechanical properties. This review provides insight for whether and how narrow-gap rheometer could be used as an efficient drug screening tool, which could further improve our current understanding of the mechanical issues present in the treatment of human diseases.
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Affiliation(s)
- Khawaja Muhammad Imran Bashir
- German Engineering Research and Development Center, LSTME-Busan Branch, Busan 46742, Korea; (K.M.I.B.); (S.L.); (D.H.J.); (M.-G.C.)
| | - Suhyang Lee
- German Engineering Research and Development Center, LSTME-Busan Branch, Busan 46742, Korea; (K.M.I.B.); (S.L.); (D.H.J.); (M.-G.C.)
- Institute of Fluid Mechanics, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), 91058 Erlangen, Germany;
| | - Dong Hee Jung
- German Engineering Research and Development Center, LSTME-Busan Branch, Busan 46742, Korea; (K.M.I.B.); (S.L.); (D.H.J.); (M.-G.C.)
- Division of Energy and Bioengineering, Dongseo University, Busan 47011, Korea
| | - Santanu Kumar Basu
- Institute of Fluid Mechanics, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), 91058 Erlangen, Germany;
| | - Man-Gi Cho
- German Engineering Research and Development Center, LSTME-Busan Branch, Busan 46742, Korea; (K.M.I.B.); (S.L.); (D.H.J.); (M.-G.C.)
- Division of Energy and Bioengineering, Dongseo University, Busan 47011, Korea
| | - Andreas Wierschem
- German Engineering Research and Development Center, LSTME-Busan Branch, Busan 46742, Korea; (K.M.I.B.); (S.L.); (D.H.J.); (M.-G.C.)
- Institute of Fluid Mechanics, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), 91058 Erlangen, Germany;
- Correspondence: ; Tel.: +49-9131-85-29566
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Hobson CM, Falvo MR, Superfine R. A survey of physical methods for studying nuclear mechanics and mechanobiology. APL Bioeng 2021; 5:041508. [PMID: 34849443 PMCID: PMC8604565 DOI: 10.1063/5.0068126] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 10/20/2021] [Indexed: 12/23/2022] Open
Abstract
It is increasingly appreciated that the cell nucleus is not only a home for DNA but also a complex material that resists physical deformations and dynamically responds to external mechanical cues. The molecules that confer mechanical properties to nuclei certainly contribute to laminopathies and possibly contribute to cellular mechanotransduction and physical processes in cancer such as metastasis. Studying nuclear mechanics and the downstream biochemical consequences or their modulation requires a suite of complex assays for applying, measuring, and visualizing mechanical forces across diverse length, time, and force scales. Here, we review the current methods in nuclear mechanics and mechanobiology, placing specific emphasis on each of their unique advantages and limitations. Furthermore, we explore important considerations in selecting a new methodology as are demonstrated by recent examples from the literature. We conclude by providing an outlook on the development of new methods and the judicious use of the current techniques for continued exploration into the role of nuclear mechanobiology.
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Affiliation(s)
| | - Michael R. Falvo
- Department of Physics and Astronomy, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Richard Superfine
- Department of Applied Physical Science, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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8
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The Mechanical Fingerprint of Circulating Tumor Cells (CTCs) in Breast Cancer Patients. Cancers (Basel) 2021; 13:cancers13051119. [PMID: 33807790 PMCID: PMC7961579 DOI: 10.3390/cancers13051119] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 02/17/2021] [Accepted: 02/26/2021] [Indexed: 12/11/2022] Open
Abstract
Simple Summary Detection of circulating tumor cells (CTCs) in the blood of cancer patients is a challenging issue, since they adapt to the biochemical and physical landscape of the bloodstream. We approached the issue of CTC identification on a biophysical level. For the first time, we recorded the mechanical deformation profiles of potential CTCs, which were isolated from the blood of breast cancer patients, at the force regime of the deforming blood flow. Mechanical fingerprints of CTCs were significantly different from healthy white blood cells. We used machine learning to further evaluate the differences and identify discrimination criteria. Our results suggest that mechanical characterization of CTCs at low forces is a promising path towards CTC detection. Abstract Circulating tumor cells (CTCs) are a potential predictive surrogate marker for disease monitoring. Due to the sparse knowledge about their phenotype and its changes during cancer progression and treatment response, CTC isolation remains challenging. Here we focused on the mechanical characterization of circulating non-hematopoietic cells from breast cancer patients to evaluate its utility for CTC detection. For proof of premise, we used healthy peripheral blood mononuclear cells (PBMCs), human MDA-MB 231 breast cancer cells and human HL-60 leukemia cells to create a CTC model system. For translational experiments CD45 negative cells—possible CTCs—were isolated from blood samples of patients with mamma carcinoma. Cells were mechanically characterized in the optical stretcher (OS). Active and passive cell mechanical data were related with physiological descriptors by a random forest (RF) classifier to identify cell type specific properties. Cancer cells were well distinguishable from PBMC in cell line tests. Analysis of clinical samples revealed that in PBMC the elliptic deformation was significantly increased compared to non-hematopoietic cells. Interestingly, non-hematopoietic cells showed significantly higher shape restoration. Based on Kelvin–Voigt modeling, the RF algorithm revealed that elliptic deformation and shape restoration were crucial parameters and that the OS discriminated non-hematopoietic cells from PBMC with an accuracy of 0.69, a sensitivity of 0.74, and specificity of 0.63. The CD45 negative cell population in the blood of breast cancer patients is mechanically distinguishable from healthy PBMC. Together with cell morphology, the mechanical fingerprint might be an appropriate tool for marker-free CTC detection.
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9
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A Universal Model for the Log-Normal Distribution of Elasticity in Polymeric Gels and Its Relevance to Mechanical Signature of Biological Tissues. BIOLOGY 2021; 10:biology10010064. [PMID: 33477413 PMCID: PMC7830536 DOI: 10.3390/biology10010064] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/08/2021] [Accepted: 01/15/2021] [Indexed: 01/19/2023]
Abstract
Simple Summary Mechanical properties of biological tissues are increasingly recognized as important in biology. Atomic force microscopy (AFM) is one of the main tools used to assess elastic properties of various types of biological samples. It has been noted that elasticity values frequently follow a log-normal distribution. We propose in this communication a physical model explaining this fact, and we propose that distribution-type analysis could increase the information obtained from AFM studies on biological tissues. Abstract The mechanosensitivity of cells has recently been identified as a process that could greatly influence a cell’s fate. To understand the interaction between cells and their surrounding extracellular matrix, the characterization of the mechanical properties of natural polymeric gels is needed. Atomic force microscopy (AFM) is one of the leading tools used to characterize mechanically biological tissues. It appears that the elasticity (elastic modulus) values obtained by AFM presents a log-normal distribution. Despite its ubiquity, the log-normal distribution concerning the elastic modulus of biological tissues does not have a clear explanation. In this paper, we propose a physical mechanism based on the weak universality of critical exponents in the percolation process leading to gelation. Following this, we discuss the relevance of this model for mechanical signatures of biological tissues.
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10
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Gensbittel V, Kräter M, Harlepp S, Busnelli I, Guck J, Goetz JG. Mechanical Adaptability of Tumor Cells in Metastasis. Dev Cell 2020; 56:164-179. [PMID: 33238151 DOI: 10.1016/j.devcel.2020.10.011] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 09/18/2020] [Accepted: 10/16/2020] [Indexed: 12/12/2022]
Abstract
The most dangerous aspect of cancer lies in metastatic progression. Tumor cells will successfully form life-threatening metastases when they undergo sequential steps along a journey from the primary tumor to distant organs. From a biomechanics standpoint, growth, invasion, intravasation, circulation, arrest/adhesion, and extravasation of tumor cells demand particular cell-mechanical properties in order to survive and complete the metastatic cascade. With metastatic cells usually being softer than their non-malignant counterparts, high deformability for both the cell and its nucleus is thought to offer a significant advantage for metastatic potential. However, it is still unclear whether there is a finely tuned but fixed mechanical state that accommodates all mechanical features required for survival throughout the cascade or whether tumor cells need to dynamically refine their properties and intracellular components at each new step encountered. Here, we review the various mechanical requirements successful cancer cells might need to fulfill along their journey and speculate on the possibility that they dynamically adapt their properties accordingly. The mechanical signature of a successful cancer cell might actually be its ability to adapt to the successive microenvironmental constraints along the different steps of the journey.
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Affiliation(s)
- Valentin Gensbittel
- INSERM UMR_S1109, Tumor Biomechanics, Strasbourg, France; Université de Strasbourg, Strasbourg, France; Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France
| | - Martin Kräter
- Max Planck Institute for the Science of Light & Max-Planck-Zentrum für Physik und Medizin, Erlangen, Germany
| | - Sébastien Harlepp
- INSERM UMR_S1109, Tumor Biomechanics, Strasbourg, France; Université de Strasbourg, Strasbourg, France; Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France
| | - Ignacio Busnelli
- INSERM UMR_S1109, Tumor Biomechanics, Strasbourg, France; Université de Strasbourg, Strasbourg, France; Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France
| | - Jochen Guck
- Max Planck Institute for the Science of Light & Max-Planck-Zentrum für Physik und Medizin, Erlangen, Germany.
| | - Jacky G Goetz
- INSERM UMR_S1109, Tumor Biomechanics, Strasbourg, France; Université de Strasbourg, Strasbourg, France; Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France.
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11
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Abstract
Miniaturization and integration of optical tweezers are attractive. Optical fiber-based trapping systems allow optical traps to be realized in miniature systems, but the optical traps in these systems lack reliability or mobility. Here, we present the all-fiber modular optical tweezers (AFMOTs), in which an optical trap can be reliably created and freely moved on a sample substrate. Two inclined optical fibers are permanently fixed to a common board, rendering a modular system where fiber alignments are maintained over months. The freely movable optical trap allows particles to be trapped in their native locations. As a demonstration, we applied AFMOTs to trap and deform freely floating individual cells. By the cell mechanical responses, we differentiated the nontumorigenic breast epithelial cell line (MCF10A) from its cancerous PTEN mutants (MCF10 PTEN-/-). To further expand the functionalities, three modalities of AFMOTs are demonstrated by changing the types of fibers for both the optical trap creation and particle position detection. As a miniature and modular system that creates a reliable and mobile optical trap, AFMOTs can find potential applications ranging from point-of-care diagnostics to education, as well as helping transition the optical trapping technology from the research lab to the field.
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12
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Taubenberger AV, Baum B, Matthews HK. The Mechanics of Mitotic Cell Rounding. Front Cell Dev Biol 2020; 8:687. [PMID: 32850812 PMCID: PMC7423972 DOI: 10.3389/fcell.2020.00687] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 07/06/2020] [Indexed: 12/21/2022] Open
Abstract
When animal cells enter mitosis, they round up to become spherical. This shape change is accompanied by changes in mechanical properties. Multiple studies using different measurement methods have revealed that cell surface tension, intracellular pressure and cortical stiffness increase upon entry into mitosis. These cell-scale, biophysical changes are driven by alterations in the composition and architecture of the contractile acto-myosin cortex together with osmotic swelling and enable a mitotic cell to exert force against the environment. When the ability of cells to round is limited, for example by physical confinement, cells suffer severe defects in spindle assembly and cell division. The requirement to push against the environment to create space for spindle formation is especially important for cells dividing in tissues. Here we summarize the evidence and the tools used to show that cells exert rounding forces in mitosis in vitro and in vivo, review the molecular basis for this force generation and discuss its function for ensuring successful cell division in single cells and for cells dividing in normal or diseased tissues.
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Affiliation(s)
- Anna V. Taubenberger
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische Universität Dresden, Dresden, Germany
| | - Buzz Baum
- MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | - Helen K. Matthews
- MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
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13
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Sousa SC, Sousa MM. The cytoskeleton as a modulator of tension driven axon elongation. Dev Neurobiol 2020; 81:300-309. [PMID: 32302060 DOI: 10.1002/dneu.22747] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Revised: 02/11/2020] [Accepted: 04/09/2020] [Indexed: 02/07/2023]
Abstract
Throughout development, neurons are capable of integrating external and internal signals leading to the morphological changes required for neuronal polarization and axon growth. The first phase of axon elongation occurs during neuronal polarization. At this stage, membrane remodeling and cytoskeleton dynamics are crucial for the growth cone to advance and guide axon elongation. When a target is recognized, the growth cone collapses to form the presynaptic terminal. Once a synapse is established, the growth of the organism results in an increased distance between the neuronal cell bodies and their targets. In this second phase of axon elongation, growth cone-independent molecular mechanisms and cytoskeleton changes must occur to enable axon growth to accompany the increase in body size. While the field has mainly focused on growth-cone mediated axon elongation during development, tension driven axon growth remains largely unexplored. In this review, we will discuss in a critical perspective the current knowledge on the mechanisms guiding axon growth following synaptogenesis, with a particular focus on the putative role played by the axonal cytoskeleton.
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Affiliation(s)
- Sara C Sousa
- Nerve Regeneration group, Instituto de Biologia Molecular e Celular - IBMC and i3S, Instituto de Inovação e Investigação em Saúde, University of Porto, Porto, Portugal.,Doctoral Program in Molecular and Cell Biology, Instituto de Ciências Biomédicas Abel Salazar-ICBAS, University of Porto, Porto, Portugal
| | - Mónica M Sousa
- Nerve Regeneration group, Instituto de Biologia Molecular e Celular - IBMC and i3S, Instituto de Inovação e Investigação em Saúde, University of Porto, Porto, Portugal
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14
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Shen Y, Schmidt BUS, Kubitschke H, Morawetz EW, Wolf B, Käs JA, Losert W. Detecting heterogeneity in and between breast cancer cell lines. CANCER CONVERGENCE 2020; 4:1. [PMID: 32090168 PMCID: PMC6997265 DOI: 10.1186/s41236-020-0010-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 01/15/2020] [Indexed: 02/07/2023] Open
Abstract
Background Cellular heterogeneity in tumor cells is a well-established phenomenon. Genetic and phenotypic cell-to-cell variability have been observed in numerous studies both within the same type of cancer cells and across different types of cancers. Another known fact for metastatic tumor cells is that they tend to be softer than their normal or non-metastatic counterparts. However, the heterogeneity of mechanical properties in tumor cells are not widely studied. Results Here we analyzed single-cell optical stretcher data with machine learning algorithms on three different breast tumor cell lines and show that similar heterogeneity can also be seen in mechanical properties of cells both within and between breast tumor cell lines. We identified two clusters within MDA-MB-231 cells, with cells in one cluster being softer than in the other. In addition, we show that MDA-MB-231 cells and MDA-MB-436 cells which are both epithelial breast cancer cell lines with a mesenchymal-like phenotype derived from metastatic cancers are mechanically more different from each other than from non-malignant epithelial MCF-10A cells. Conclusion Since stiffness of tumor cells can be an indicator of metastatic potential, this result suggests that metastatic abilities could vary within the same monoclonal tumor cell line.
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Affiliation(s)
- Yang Shen
- 1Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742 USA
| | - B U Sebastian Schmidt
- 1Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742 USA
| | - Hans Kubitschke
- 2Peter Debye Institute for Soft Matter Physics, Leipzig University, Linnéstr. 5, 04103 Leipzig, Germany
| | - Erik W Morawetz
- 2Peter Debye Institute for Soft Matter Physics, Leipzig University, Linnéstr. 5, 04103 Leipzig, Germany
| | - Benjamin Wolf
- Leipzig University Medical Center, Department of Obstetrics and Gynecology, Liebigstr. 20a, 04103 Leipzig, Germany
| | - Josef A Käs
- 2Peter Debye Institute for Soft Matter Physics, Leipzig University, Linnéstr. 5, 04103 Leipzig, Germany
| | - Wolfgang Losert
- 1Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742 USA
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Kunschmann T, Puder S, Fischer T, Steffen A, Rottner K, Mierke CT. The Small GTPase Rac1 Increases Cell Surface Stiffness and Enhances 3D Migration Into Extracellular Matrices. Sci Rep 2019; 9:7675. [PMID: 31118438 PMCID: PMC6531482 DOI: 10.1038/s41598-019-43975-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 05/07/2019] [Indexed: 01/21/2023] Open
Abstract
Membrane ruffling and lamellipodia formation promote the motility of adherent cells in two-dimensional motility assays by mechano-sensing of the microenvironment and initiation of focal adhesions towards their surroundings. Lamellipodium formation is stimulated by small Rho GTPases of the Rac subfamily, since genetic removal of these GTPases abolishes lamellipodium assembly. The relevance of lamellipodial or invadopodial structures for facilitating cellular mechanics and 3D cell motility is still unclear. Here, we hypothesized that Rac1 affects cell mechanics and facilitates 3D invasion. Thus, we explored whether fibroblasts that are genetically deficient for Rac1 (lacking Rac2 and Rac3) harbor altered mechanical properties, such as cellular deformability, intercellular adhesion forces and force exertion, and exhibit alterations in 3D motility. Rac1 knockout and control cells were analyzed for changes in deformability by applying an external force using an optical stretcher. Five Rac1 knockout cell lines were pronouncedly more deformable than Rac1 control cells upon stress application. Using AFM, we found that cell-cell adhesion forces are increased in Rac1 knockout compared to Rac1-expressing fibroblasts. Since mechanical deformability, cell-cell adhesion strength and 3D motility may be functionally connected, we investigated whether increased deformability of Rac1 knockout cells correlates with changes in 3D motility. All five Rac1 knockout clones displayed much lower 3D motility than Rac1-expressing controls. Moreover, force exertion was reduced in Rac1 knockout cells, as assessed by 3D fiber displacement analysis. Interference with cellular stiffness through blocking of actin polymerization by Latrunculin A could not further reduce invasion of Rac1 knockout cells. In contrast, Rac1-expressing controls treated with Latrunculin A were again more deformable and less invasive, suggesting actin polymerization is a major determinant of observed Rac1-dependent effects. Together, we propose that regulation of 3D motility by Rac1 partly involves cellular mechanics such as deformability and exertion of forces.
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Affiliation(s)
- Tom Kunschmann
- University of Leipzig, Faculty of Physics and Earth Science, Peter Debye Institute of Soft Matter Physics, Biological Physics Division, Linnestr. 5, 04103, Leipzig, Germany
| | - Stefanie Puder
- University of Leipzig, Faculty of Physics and Earth Science, Peter Debye Institute of Soft Matter Physics, Biological Physics Division, Linnestr. 5, 04103, Leipzig, Germany
| | - Tony Fischer
- University of Leipzig, Faculty of Physics and Earth Science, Peter Debye Institute of Soft Matter Physics, Biological Physics Division, Linnestr. 5, 04103, Leipzig, Germany
| | - Anika Steffen
- Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124, Braunschweig, Germany
| | - Klemens Rottner
- Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124, Braunschweig, Germany
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstr. 7, 38106, Braunschweig, Germany
| | - Claudia Tanja Mierke
- University of Leipzig, Faculty of Physics and Earth Science, Peter Debye Institute of Soft Matter Physics, Biological Physics Division, Linnestr. 5, 04103, Leipzig, Germany.
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16
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Kang JH, Miettinen TP, Chen L, Olcum S, Katsikis G, Doyle PS, Manalis SR. Noninvasive monitoring of single-cell mechanics by acoustic scattering. Nat Methods 2019; 16:263-269. [PMID: 30742041 PMCID: PMC6420125 DOI: 10.1038/s41592-019-0326-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 01/09/2019] [Indexed: 02/05/2023]
Abstract
Monitoring mechanics of the same cell throughout the cell cycle has been hampered by the invasiveness of mechanical measurements. Here, we quantify mechanical properties via acoustic scattering of waves from a cell inside a fluid-filled vibrating cantilever with a temporal resolution of <1 min. Through simulations, experiments with hydrogels and chemically perturbed cells, we show that our readout, the size-normalized acoustic scattering (SNACS), measures stiffness. We demonstrate the noninvasiveness of SNACS over successive cell cycles using measurements that result in < 15 nm deformations. Cells maintain constant SNACS throughout interphase but exhibit dynamic changes during mitosis. Our work provides a basis for understanding how growing cells maintain mechanical integrity and demonstrates that acoustic scattering can non-invasively probe subtle and transient dynamics.
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Affiliation(s)
- Joon Ho Kang
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA.,Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Teemu P Miettinen
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA.,MRC Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Lynna Chen
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Selim Olcum
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Georgios Katsikis
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Patrick S Doyle
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA.,Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Scott R Manalis
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA. .,Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA. .,Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
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17
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Analysis of Biomechanical Properties of Hematopoietic Stem and Progenitor Cells Using Real-Time Fluorescence and Deformability Cytometry. Methods Mol Biol 2019; 2017:135-148. [PMID: 31197774 DOI: 10.1007/978-1-4939-9574-5_11] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Stem cell mechanics, determined predominantly by the cell's cytoskeleton, plays an important role in different biological processes such as stem cell differentiation or migration. Several methods to measure mechanical properties of cells are currently available, but most of them are limited in the ability to screen large heterogeneous populations in a robust and efficient manner-a feature required for successful translational applications. With real-time fluorescence and deformability cytometry (RT-FDC), mechanical properties of cells in suspension can be screened continuously at rates of up to 1,000 cells/s-similar to conventional flow cytometers-which makes it a suitable method not only for basic research but also for a clinical setting. In parallel to mechanical characterization, RT-FDC allows to measure specific molecular markers using standard fluorescence labeling. In this chapter, we provide a detailed protocol for the characterization of hematopoietic stem and progenitor cells (HSPCs) in heterogeneous mobilized peripheral blood using RT-FDC and present a specific morpho-rheological fingerprint of HSPCs that allows to distinguish them from all other blood cell types.
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18
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Lipowsky HH, Bowers DT, Banik BL, Brown JL. Mesenchymal Stem Cell Deformability and Implications for Microvascular Sequestration. Ann Biomed Eng 2018; 46:640-654. [PMID: 29352448 PMCID: PMC5862759 DOI: 10.1007/s10439-018-1985-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 01/16/2018] [Indexed: 02/07/2023]
Abstract
Mesenchymal stem cells (MSCs) have received considerable attention in regenerative medicine, particularly in light of prospects for targeted delivery by intra-arterial injection. However, little is known about the mechanics of MSC sequestration in the microvasculature and the yield pressure (PY), above which MSCs will pass through microvessels of a given diameter. The objectives of the current study were to delineate the dependency of PY on cell size and the heterogeneity of cell mechanical properties and diameters (DCELL) of cultured MSCs. To this end the transient filtration test was employed to elucidate the mean filtration pressure (〈PY〉) for an ensemble of pores of a given size (DPORE) similar to in vivo microvessels. Cultured MSCs had a log-normal distribution of cell diameters (DCELL) with a mean of 15.8 ± 0.73 SD μm. MSC clearance from track-etched polycarbonate filters was studied for pore diameters of 7.3-15.4 μm. The pressure required to clear cells from filters with 30-85 × 103 pores rose exponentially with the ratio λ = DCELL/DPORE for 1.1 ≤ λ ≤ 2.2. The clearance of cells from each filter was characterized by a log-normal distribution in PY, with a mean filtration pressure of 0.02 ≤ 〈PY〉 ≤ 6.7 cmH2O. For λ ≤ 1.56, the yield pressure (PY) was well represented by the cortical shell model of a cell with a viscous interior encapsulated by a shell under cortical tension τ0 = 0.99 ± 0.42 SD dyn/cm. For λ > 1.56, the 〈PY〉 characteristic of the cell population rose exponentially with λ. Analysis of the mean filtration pressure (〈PY〉) of each sample suggested that the larger diameter cells that skewed the distribution of DCELL contributed to about 20% of the mean filtration pressure. Further, if all cells had the same deformability (i.e., PY as a function of λ) as the average cell population, then 〈PY〉 would have risen an order of magnitude above the average from fivefold at λ = 1.56 to 200-fold at λ = 2.1. Comparison of 〈PY〉 to published microvascular pressures suggested that 〈PY〉 may exceed microvessel pressure drops for λ exceeding 2.1, and rise 14-fold above capillary pressure drop at λ = 3 leading to 100% sequestration. However, due to the large variance of in vivo microvascular pressures entrapment of MSCs may be mitigated. Thus it is suggested that selecting fractions of the MSC population according to cell deformability may permit optimization of entrapment at sites targeted for tissue regeneration.
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Affiliation(s)
- Herbert H Lipowsky
- Department of Biomedical Engineering, The Pennsylvania State University, 215 Hallowell Bldg, University Park, PA, 16802, USA.
| | - Daniel T Bowers
- Department of Biomedical Engineering, The Pennsylvania State University, 215 Hallowell Bldg, University Park, PA, 16802, USA
| | - Brittany L Banik
- Department of Biomedical Engineering, The Pennsylvania State University, 215 Hallowell Bldg, University Park, PA, 16802, USA
| | - Justin L Brown
- Department of Biomedical Engineering, The Pennsylvania State University, 215 Hallowell Bldg, University Park, PA, 16802, USA
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19
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Schürmann M, Cojoc G, Girardo S, Ulbricht E, Guck J, Müller P. Three-dimensional correlative single-cell imaging utilizing fluorescence and refractive index tomography. JOURNAL OF BIOPHOTONICS 2018; 11. [PMID: 28800386 DOI: 10.1002/jbio.201700145] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 08/04/2017] [Accepted: 08/09/2017] [Indexed: 05/14/2023]
Abstract
Cells alter the path of light, a fact that leads to well-known aberrations in single cell or tissue imaging. Optical diffraction tomography (ODT) measures the biophysical property that causes these aberrations, the refractive index (RI). ODT is complementary to fluorescence imaging and does not require any markers. The present study introduces RI and fluorescence tomography with optofluidic rotation (RAFTOR) of suspended cells, facilitating the segmentation of the 3D-correlated RI and fluorescence data for a quantitative interpretation of the nuclear RI. The technique is validated with cell phantoms and used to confirm a lower nuclear RI for HL60 cells. Furthermore, the nuclear inversion of adult mouse photoreceptor cells is observed in the RI distribution. The applications shown confirm predictions of previous studies and illustrate the potential of RAFTOR to improve our understanding of cells and tissues.
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Affiliation(s)
| | - Gheorghe Cojoc
- Biotechnology Center of the TU Dresden, Dresden, Germany
| | | | - Elke Ulbricht
- Biotechnology Center of the TU Dresden, Dresden, Germany
| | - Jochen Guck
- Biotechnology Center of the TU Dresden, Dresden, Germany
| | - Paul Müller
- Biotechnology Center of the TU Dresden, Dresden, Germany
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20
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Murphy TW, Zhang Q, Naler LB, Ma S, Lu C. Recent advances in the use of microfluidic technologies for single cell analysis. Analyst 2017; 143:60-80. [PMID: 29170786 PMCID: PMC5839671 DOI: 10.1039/c7an01346a] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The inherent heterogeneity in cell populations has become of great interest and importance as analytical techniques have improved over the past decades. With the advent of personalized medicine, understanding the impact of this heterogeneity has become an important challenge for the research community. Many different microfluidic approaches with varying levels of throughput and resolution exist to study single cell activity. In this review, we take a broad view of the recent microfluidic developments in single cell analysis based on microwell, microchamber, and droplet platforms. We cover physical, chemical, and molecular biology approaches for cellular and molecular analysis including newly emerging genome-wide analysis.
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Affiliation(s)
- Travis W Murphy
- Department of Chemical Engineering, Virginia Tech, Blacksburg, VA 24061, USA.
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21
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Gullekson C, Cojoc G, Schürmann M, Guck J, Pelling A. Mechanical mismatch between Ras transformed and untransformed epithelial cells. SOFT MATTER 2017; 13:8483-8491. [PMID: 29091102 DOI: 10.1039/c7sm01396e] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The organization of the actin cytoskeleton plays a key role in regulating cell mechanics. It is fundamentally altered during transformation, affecting how cells interact with their environment. We investigated mechanical properties of cells expressing constitutively active, oncogenic Ras (RasV12) in adherent and suspended states. To do this, we utilized atomic force microscopy and a microfluidic optical stretcher. We found that adherent cells stiffen and suspended cells soften with the expression of constitutively active Ras. The effect on adherent cells was reversed when contractility was inhibited with the ROCK inhibitor Y-27632, resulting in softer RasV12 cells. Our findings suggest that increased ROCK activity as a result of Ras has opposite effects on suspended and adhered cells. Our results also establish the importance of the activation of ROCK by Ras and its effect on cell mechanics.
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Affiliation(s)
- Corinne Gullekson
- Centre for Interdisciplinary NanoPhysics, Department of Physics, University of Ottawa, 598 King Edward, Ottawa, ON, K1N5N5 Canada.
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22
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Chan CJ, Li W, Cojoc G, Guck J. Volume Transitions of Isolated Cell Nuclei Induced by Rapid Temperature Increase. Biophys J 2017; 112:1063-1076. [PMID: 28355535 PMCID: PMC5374986 DOI: 10.1016/j.bpj.2017.01.022] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 01/10/2017] [Accepted: 01/17/2017] [Indexed: 02/07/2023] Open
Abstract
Understanding the physical mechanisms governing nuclear mechanics is important as it can impact gene expression and development. However, how cell nuclei respond to external cues such as heat is not well understood. Here, we studied the material properties of isolated nuclei in suspension using an optical stretcher. We demonstrate that isolated nuclei regulate their volume in a highly temperature-sensitive manner. At constant temperature, isolated nuclei behaved like passive, elastic and incompressible objects, whose volume depended on the pH and ionic conditions. When the temperature was increased suddenly by even a few degrees Kelvin, nuclei displayed a repeatable and reversible temperature-induced volume transition, whose sign depended on the valency of the solvent. Such phenomenon is not observed for nuclei subjected to slow heating. The transition temperature could be shifted by adiabatic changes of the ambient temperature, and the magnitude of temperature-induced volume transition could be modulated by modifying the chromatin compaction state and remodeling processes. Our findings reveal that the cell nucleus can be viewed as a highly charged polymer gel with intriguing thermoresponsive properties, which might play a role in nuclear volume regulation and thermosensing in living cells.
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Affiliation(s)
- Chii J Chan
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, United Kingdom; Biotechnology Center, Technische Universität Dresden, Dresden, Germany.
| | - Wenhong Li
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Gheorghe Cojoc
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Jochen Guck
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, United Kingdom; Biotechnology Center, Technische Universität Dresden, Dresden, Germany.
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23
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Morawetz EW, Stange R, Kießling TR, Schnauß J, Käs JA. Optical stretching in continuous flows. CONVERGENT SCIENCE PHYSICAL ONCOLOGY 2017. [DOI: 10.1088/2057-1739/aa6eb1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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24
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Waigh TA. Advances in the microrheology of complex fluids. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2016; 79:074601. [PMID: 27245584 DOI: 10.1088/0034-4885/79/7/074601] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
New developments in the microrheology of complex fluids are considered. Firstly the requirements for a simple modern particle tracking microrheology experiment are introduced, the error analysis methods associated with it and the mathematical techniques required to calculate the linear viscoelasticity. Progress in microrheology instrumentation is then described with respect to detectors, light sources, colloidal probes, magnetic tweezers, optical tweezers, diffusing wave spectroscopy, optical coherence tomography, fluorescence correlation spectroscopy, elastic- and quasi-elastic scattering techniques, 3D tracking, single molecule methods, modern microscopy methods and microfluidics. New theoretical techniques are also reviewed such as Bayesian analysis, oversampling, inversion techniques, alternative statistical tools for tracks (angular correlations, first passage probabilities, the kurtosis, motor protein step segmentation etc), issues in micro/macro rheological agreement and two particle methodologies. Applications where microrheology has begun to make some impact are also considered including semi-flexible polymers, gels, microorganism biofilms, intracellular methods, high frequency viscoelasticity, comb polymers, active motile fluids, blood clots, colloids, granular materials, polymers, liquid crystals and foods. Two large emergent areas of microrheology, non-linear microrheology and surface microrheology are also discussed.
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Affiliation(s)
- Thomas Andrew Waigh
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Rd., Manchester, M13 9PL, UK. Photon Science Institute, University of Manchester, Oxford Rd., Manchester, M13 9PL, UK
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25
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Yang T, Bragheri F, Minzioni P. A Comprehensive Review of Optical Stretcher for Cell Mechanical Characterization at Single-Cell Level. MICROMACHINES 2016; 7:E90. [PMID: 30404265 PMCID: PMC6189960 DOI: 10.3390/mi7050090] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 04/14/2016] [Accepted: 04/21/2016] [Indexed: 11/21/2022]
Abstract
This paper presents a comprehensive review of the development of the optical stretcher, a powerful optofluidic device for single cell mechanical study by using optical force induced cell stretching. The different techniques and the different materials for the fabrication of the optical stretcher are first summarized. A short description of the optical-stretching mechanism is then given, highlighting the optical force calculation and the cell optical deformability characterization. Subsequently, the implementations of the optical stretcher in various cell-mechanics studies are shown on different types of cells. Afterwards, two new advancements on optical stretcher applications are also introduced: the active cell sorting based on cell mechanical characterization and the temperature effect on cell stretching measurement from laser-induced heating. Two examples of new functionalities developed with the optical stretcher are also included. Finally, the current major limitation and the future development possibilities are discussed.
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Affiliation(s)
- Tie Yang
- Department of Electrical, Computer, and Biomedical Engineering, Università di Pavia, Via Ferrata 5A, Pavia 27100, Italy.
| | - Francesca Bragheri
- Institute of Photonics and Nanotechnology, CNR & Department of Physics, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milano 20133, Italy.
| | - Paolo Minzioni
- Department of Electrical, Computer, and Biomedical Engineering, Università di Pavia, Via Ferrata 5A, Pavia 27100, Italy.
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26
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Suriano R, Zandrini T, De Marco C, Osellame R, Turri S, Bragheri F. Nanomechanical probing of soft matter through hydrophobic AFM tips fabricated by two-photon polymerization. NANOTECHNOLOGY 2016; 27:155702. [PMID: 26926558 DOI: 10.1088/0957-4484/27/15/155702] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Atomic force microscopy (AFM) nanoindentation of soft materials is a powerful tool for probing mechanical properties of biomaterials. Though many results have been reported in this field over the last decade, adhesion forces between the tip and the sample hinder the elastic modulus measurement when hydrophilic soft samples are investigated. Here, two-photon polymerization (2PP) technology was used to fabricate hydrophobic perfluoropolyether-based AFM tips. The hydrophobic 2PP tips allowed us to overcome the limitations of commercial and functionalized tips as well as to successfully measure the elastic modulus of medically relevant soft materials in air. Our results obtained in the characterization of poly(dimethyl siloxane) and polyethylene glycol hydrogels showed lower adhesion forces over a larger measurement range when compared to measurements performed with commercial tips. The elastic moduli measured by means of hydrophobic 2PP AFM tips were also found to be comparable to those obtained using conventional techniques for macroscopic samples. We successfully showed that the hydrophobic AFM tips developed by this highly versatile technology enable the study of mechanical properties of soft matter, benefiting from reduced sample-tip interactions, and a custom-made shape and dimension of the tips.
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Affiliation(s)
- Raffaella Suriano
- Dipartimento di Chimica, Materiali e Ingegneria Chimica 'Giulio Natta', Politecnico di Milano, P.zza Leonardo da Vinci 32, 20133 Milano, Italy
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27
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Martinez Vazquez R, Nava G, Veglione M, Yang T, Bragheri F, Minzioni P, Bianchi E, Di Tano M, Chiodi I, Osellame R, Mondello C, Cristiani I. An optofluidic constriction chip for monitoring metastatic potential and drug response of cancer cells. Integr Biol (Camb) 2015; 7:477-84. [PMID: 25804890 DOI: 10.1039/c5ib00023h] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cellular mechanical properties constitute good markers to characterize tumor cells, to study cell population heterogeneity and to highlight the effect of drug treatments. In this work, we describe the fabrication and validation of an integrated optofluidic chip capable of analyzing cellular deformability on the basis of the pressure gradient needed to push a cell through a narrow constriction. We demonstrate the ability of the chip to discriminate between tumorigenic and metastatic breast cancer cells (MCF7 and MDA-MB231) and between human melanoma cells with different metastatic potential (A375P and A375MC2). Moreover, we show that this chip allows highlighting the effect of drugs interfering with microtubule organization (paclitaxel, combretastatin A-4 and nocodazole) on cancer cells, which leads to changes in the pressure-gradient required to push cells through the constriction. Our single-cell microfluidic device for mechanical evaluation is compact and easy to use, allowing for an extensive use in different laboratory environments.
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Affiliation(s)
- R Martinez Vazquez
- Istituto di Fotonica e Nanotecnologie (IFN)-CNR, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
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28
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Spagnol ST, Lin WC, Booth EA, Ladoux B, Lazarus HM, Dahl KN. Early Passage Dependence of Mesenchymal Stem Cell Mechanics Influences Cellular Invasion and Migration. Ann Biomed Eng 2015; 44:2123-31. [PMID: 26581348 DOI: 10.1007/s10439-015-1508-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 11/11/2015] [Indexed: 02/06/2023]
Abstract
The cellular structures and mechanical properties of human mesenchymal stem cells (hMSCs) vary significantly during culture and with differentiation. Previously, studies to measure mechanics have provided divergent results using different quantitative parameters and mechanical models of deformation. Here, we examine hMSCs prepared for clinical use and subject them to mechanical testing conducive to the relevant deformability associated with clinical injection procedures. Micropipette aspiration of hMSCs shows deformation as a viscoelastic fluid, with little variation from cell to cell within a population. After two passages, hMSCs deform as viscoelastic solids. Further, for clinical applicability during stem cell migration in vivo, we investigated the ability of hMSCs to invade into micropillar arrays of increasing confinement from 12 to 8 μm spacing between adjacent micropillars. We find that hMSC samples with reduced deformability and cells that are more solid-like with passage are more easily able to enter the micropillar arrays. Increased cell fluidity is an advantage for injection procedures and optimization of cell selection based on mechanical properties may enhance efficacy of injected hMSC populations. However, the ability to invade and migrate within tight interstitial spaces appears to be increased with a more solidified cytoskeleton, likely from increased force generation and contractility. Thus, there may be a balance between optimal injection survival and in situ tissue invasion.
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Affiliation(s)
- Stephen T Spagnol
- Department of Chemical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA, 15213, USA
| | - Wei-Chun Lin
- Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Elizabeth A Booth
- Department of Chemical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA, 15213, USA
| | - Benoit Ladoux
- Institut Jacques Monod (IJM), CNRS UMR 7592 & Université Paris Diderot, Paris, France
- Mechanobiology Institute, National University of Singapore, Singapore, Singapore
| | - Hillard M Lazarus
- Division of Hematology and Oncology, Department of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Kris Noel Dahl
- Department of Chemical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA, 15213, USA.
- Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA.
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29
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Delabre U, Feld K, Crespo E, Whyte G, Sykes C, Seifert U, Guck J. Deformation of phospholipid vesicles in an optical stretcher. SOFT MATTER 2015; 11:6075-88. [PMID: 26135540 DOI: 10.1039/c5sm00562k] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Phospholipid vesicles are common model systems for cell membranes. Important aspects of the membrane function relate to its mechanical properties. Here we have investigated the deformation behaviour of phospholipid vesicles in a dual-beam laser trap, also called an optical stretcher. This study explicitly makes use of the inherent heating present in such traps to investigate the dependence of vesicle deformation on temperature. By using lasers with different wavelengths, optically induced mechanical stresses and temperature increase can be tuned fairly independently with a single setup. The phase transition temperature of vesicles can be clearly identified by an increase in deformation. In the case of no heating effects, a minimal model for drop deformation in an optical stretcher and a more specific model for vesicle deformation that takes explicitly into account the angular dependence of the optical stress are presented to account for the experimental results. Elastic constants are extracted from the fitting procedures, which agree with literature data. This study demonstrates the utility of optical stretching, which is easily combined with microfluidic delivery, for the future serial, high-throughput study of the mechanical and thermodynamic properties of phospholipid vesicles.
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Affiliation(s)
- Ulysse Delabre
- Univ. Bordeaux, CNRS, Laboratoire Ondes et Matière d'Aquitaine, UMR 5798, F-33400 Talence, France.
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Boltze J, Arnold A, Walczak P, Jolkkonen J, Cui L, Wagner DC. The Dark Side of the Force - Constraints and Complications of Cell Therapies for Stroke. Front Neurol 2015; 6:155. [PMID: 26257702 PMCID: PMC4507146 DOI: 10.3389/fneur.2015.00155] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 06/23/2015] [Indexed: 12/16/2022] Open
Abstract
Cell therapies are increasingly recognized as a promising option to augment the limited therapeutic arsenal available to fight ischemic stroke. During the last two decades, cumulating preclinical evidence has indicated a substantial efficacy for most cell treatment paradigms and first clinical trials are currently underway to assess safety and feasibility in patients. However, the strong and still unmet demand for novel stroke treatment options and exciting findings reported from experimental studies may have drawn our attention away from potential side effects related to cell therapies and the ways by which they are commonly applied. This review summarizes common and less frequent adverse events that have been discovered in preclinical and clinical investigations assessing cell therapies for stroke. Such adverse events range from immunological and neoplastic complications over seizures to cell clotting and cell-induced embolism. It also describes potential complications of clinically applicable administration procedures, detrimental interactions between therapeutic cells, and the pathophysiological environment that they are placed into, as well as problems related to cell manufacturing. Virtually each therapeutic intervention comes at a certain risk for complications. Side effects do therefore not generally compromise the value of cell treatments for stroke, but underestimating such complications might severely limit therapeutic safety and efficacy of cell treatment protocols currently under development. On the other hand, a better understanding will provide opportunities to further improve existing therapeutic strategies and might help to define those circumstances, under which an optimal effect can be realized. Hence, the review eventually discusses strategies and recommendations allowing us to prevent or at least balance potential complications in order to ensure the maximum therapeutic benefit at minimum risk for stroke patients.
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Affiliation(s)
- Johannes Boltze
- Department of Cell Therapy, Fraunhofer-Institute for Cell Therapy and Immunology , Leipzig , Germany ; Translational Center for Regenerative Medicine, University of Leipzig , Leipzig , Germany
| | - Antje Arnold
- Division of MR Research, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine , Baltimore, MD , USA ; Institute for Cell Engineering, Johns Hopkins University , Baltimore, MD , USA
| | - Piotr Walczak
- Division of MR Research, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine , Baltimore, MD , USA ; Institute for Cell Engineering, Johns Hopkins University , Baltimore, MD , USA
| | - Jukka Jolkkonen
- Department of Neurology, Institute of Clinical Medicine, University of Eastern Finland , Kuopio , Finland
| | - Lili Cui
- Department of Neurology, Institute of Clinical Medicine, University of Eastern Finland , Kuopio , Finland
| | - Daniel-Christoph Wagner
- Department of Cell Therapy, Fraunhofer-Institute for Cell Therapy and Immunology , Leipzig , Germany
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31
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Abstract
Traditionally, cell analysis has focused on using molecular biomarkers for basic research, cell preparation, and clinical diagnostics; however, new microtechnologies are enabling evaluation of the mechanical properties of cells at throughputs that make them amenable to widespread use. We review the current understanding of how the mechanical characteristics of cells relate to underlying molecular and architectural changes, describe how these changes evolve with cell-state and disease processes, and propose promising biomedical applications that will be facilitated by the increased throughput of mechanical testing: from diagnosing cancer and monitoring immune states to preparing cells for regenerative medicine. We provide background about techniques that laid the groundwork for the quantitative understanding of cell mechanics and discuss current efforts to develop robust techniques for rapid analysis that aim to implement mechanophenotyping as a routine tool in biomedicine. Looking forward, we describe additional milestones that will facilitate broad adoption, as well as new directions not only in mechanically assessing cells but also in perturbing them to passively engineer cell state.
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Affiliation(s)
- Eric M Darling
- Center for Biomedical Engineering.,Department of Molecular Pharmacology, Physiology, and Biotechnology.,Department of Orthopaedics, and.,School of Engineering, Brown University, Providence, Rhode Island 02912;
| | - Dino Di Carlo
- Department of Bioengineering.,California NanoSystems Institute, and.,Jonsson Comprehensive Cancer Center, University of California, Los Angeles, California 90095;
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32
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Faigle C, Lautenschläger F, Whyte G, Homewood P, Martín-Badosa E, Guck J. A monolithic glass chip for active single-cell sorting based on mechanical phenotyping. LAB ON A CHIP 2015; 15:1267-1275. [PMID: 25537986 DOI: 10.1039/c4lc01196a] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The mechanical properties of biological cells have long been considered as inherent markers of biological function and disease. However, the screening and active sorting of heterogeneous populations based on serial single-cell mechanical measurements has not been demonstrated. Here we present a novel monolithic glass chip for combined fluorescence detection and mechanical phenotyping using an optical stretcher. A new design and manufacturing process, involving the bonding of two asymmetrically etched glass plates, combines exact optical fiber alignment, low laser damage threshold and high imaging quality with the possibility of several microfluidic inlet and outlet channels. We show the utility of such a custom-built optical stretcher glass chip by measuring and sorting single cells in a heterogeneous population based on their different mechanical properties and verify sorting accuracy by simultaneous fluorescence detection. This offers new possibilities of exact characterization and sorting of small populations based on rheological properties for biological and biomedical applications.
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Affiliation(s)
- Christoph Faigle
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany.
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33
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Holmes D, Whyte G, Bailey J, Vergara-Irigaray N, Ekpenyong A, Guck J, Duke T. Separation of blood cells with differing deformability using deterministic lateral displacement(†). Interface Focus 2014; 4:20140011. [PMID: 25485078 PMCID: PMC4213443 DOI: 10.1098/rsfs.2014.0011] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Determining cell mechanical properties is increasingly recognized as a marker-free way to characterize and separate biological cells. This emerging realization has led to the development of a plethora of appropriate measurement techniques. Here, we use a fairly novel approach, deterministic lateral displacement (DLD), to separate blood cells based on their mechanical phenotype with high throughput. Human red blood cells were treated chemically to alter their membrane deformability and the effect of this alteration on the hydrodynamic behaviour of the cells in a DLD device was investigated. Cells of defined stiffness (glutaraldehyde cross-linked erythrocytes) were used to test the performance of the DLD device across a range of cell stiffness and applied shear rates. Optical stretching was used as an independent method for quantifying the variation in stiffness of the cells. Lateral displacement of cells flowing within the device, and their subsequent exit position from the device were shown to correlate with cell stiffness. Data showing how the isolation of leucocytes from whole blood varies with applied shear rate are also presented. The ability to sort leucocyte sub-populations (T-lymphocytes and neutrophils), based on a combination of cell size and deformability, demonstrates the potential for using DLD devices to perform continuous fractionation and/or enrichment of leucocyte sub-populations from whole blood.
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Affiliation(s)
- David Holmes
- London Centre for Nanotechnology , University College London , 17-19 Gordon Street, London WC1H 0AH , UK
| | - Graeme Whyte
- Friedrich-Alexander Universität Erlangen-Nürnberg , Henkestrasse 91, 91052 Erlangen , Germany ; Cavendish Laboratory, Department of Physics , University of Cambridge , JJ Thomson Avenue, Cambridge CB3 0HE , UK
| | - Joe Bailey
- London Centre for Nanotechnology , University College London , 17-19 Gordon Street, London WC1H 0AH , UK ; Centre for Mathematics and Physics in the Life Sciences and Experimental Biology , University College London , Gower Street, London WC1E 6BT , UK
| | - Nuria Vergara-Irigaray
- London Centre for Nanotechnology , University College London , 17-19 Gordon Street, London WC1H 0AH , UK ; Department of Genetics, Evolution and Environment, Institute of Healthy Ageing , University College London , Gower Street, London WC1E 6BT , UK
| | - Andrew Ekpenyong
- Cavendish Laboratory, Department of Physics , University of Cambridge , JJ Thomson Avenue, Cambridge CB3 0HE , UK ; Biotechnology Center , TechnischeUniversität Dresden , Tatzberg 47/49, 01307 Dresden , Germany
| | - Jochen Guck
- Cavendish Laboratory, Department of Physics , University of Cambridge , JJ Thomson Avenue, Cambridge CB3 0HE , UK ; Biotechnology Center , TechnischeUniversität Dresden , Tatzberg 47/49, 01307 Dresden , Germany
| | - Tom Duke
- London Centre for Nanotechnology , University College London , 17-19 Gordon Street, London WC1H 0AH , UK
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34
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Sawetzki T, Eggleton CD, Desai SA, Marr DWM. Viscoelasticity as a biomarker for high-throughput flow cytometry. Biophys J 2014; 105:2281-8. [PMID: 24268140 DOI: 10.1016/j.bpj.2013.10.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2013] [Revised: 09/15/2013] [Accepted: 10/01/2013] [Indexed: 11/16/2022] Open
Abstract
The mechanical properties of living cells are a label-free biophysical marker of cell viability and health; however, their use has been greatly limited by low measurement throughput. Although examining individual cells at high rates is now commonplace with fluorescence activated cell sorters, development of comparable techniques that nondestructively probe cell mechanics remains challenging. A fundamental hurdle is the signal response time. Where light scattering and fluorescence signatures are virtually instantaneous, the cell stress relaxation, typically occurring on the order of seconds, limits the potential speed of elastic property measurement. To overcome this intrinsic barrier to rapid analysis, we show here that cell viscoelastic properties measured at frequencies far higher than those associated with cell relaxation can be used as a means of identifying significant differences in cell phenotype. In these studies, we explore changes in erythrocyte mechanical properties caused by infection with Plasmodium falciparum and find that the elastic response alone fails to detect malaria at high frequencies. At timescales associated with rapid assays, however, we observe that the inelastic response shows significant changes and can be used as a reliable indicator of infection, establishing the dynamic viscoelasticity as a basis for nondestructive mechanical analogs of current high-throughput cell classification methods.
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Affiliation(s)
- Tobias Sawetzki
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado
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35
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Chalut KJ, Höpfler M, Lautenschläger F, Boyde L, Chan CJ, Ekpenyong A, Martinez-Arias A, Guck J. Chromatin decondensation and nuclear softening accompany Nanog downregulation in embryonic stem cells. Biophys J 2012. [PMID: 23200040 DOI: 10.1016/j.bpj.2012.10.015] [Citation(s) in RCA: 113] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The interplay between epigenetic modification and chromatin compaction is implicated in the regulation of gene expression, and it comprises one of the most fascinating frontiers in cell biology. Although a complete picture is still lacking, it is generally accepted that the differentiation of embryonic stem (ES) cells is accompanied by a selective condensation into heterochromatin with concomitant gene silencing, leaving access only to lineage-specific genes in the euchromatin. ES cells have been reported to have less condensed chromatin, as they are capable of differentiating into any cell type. However, pluripotency itself-even prior to differentiation-is a split state comprising a naïve state and a state in which ES cells prime for differentiation. Here, we show that naïve ES cells decondense their chromatin in the course of downregulating the pluripotency marker Nanog before they initiate lineage commitment. We used fluorescence recovery after photobleaching, and histone modification analysis paired with a novel, to our knowledge, optical stretching method, to show that ES cells in the naïve state have a significantly stiffer nucleus that is coupled to a globally more condensed chromatin state. We link this biophysical phenotype to coinciding epigenetic differences, including histone methylation, and show a strong correlation of chromatin condensation and nuclear stiffness with the expression of Nanog. Besides having implications for transcriptional regulation and embryonic cell sorting and suggesting a putative mechanosensing mechanism, the physical differences point to a system-level regulatory role of chromatin in maintaining pluripotency in embryonic development.
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Affiliation(s)
- Kevin J Chalut
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, UK.
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36
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Matthews H, Delabre U, Rohn J, Guck J, Kunda P, Baum B. Changes in Ect2 localization couple actomyosin-dependent cell shape changes to mitotic progression. Dev Cell 2012; 23:371-83. [PMID: 22898780 PMCID: PMC3763371 DOI: 10.1016/j.devcel.2012.06.003] [Citation(s) in RCA: 145] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Revised: 04/04/2012] [Accepted: 06/05/2012] [Indexed: 12/17/2022]
Abstract
As they enter mitosis, animal cells undergo profound actin-dependent changes in shape to become round. Here we identify the Cdk1 substrate, Ect2, as a central regulator of mitotic rounding, thus uncovering a link between the cell-cycle machinery that drives mitotic entry and its accompanying actin remodeling. Ect2 is a RhoGEF that plays a well-established role in formation of the actomyosin contractile ring at mitotic exit, through the local activation of RhoA. We find that Ect2 first becomes active in prophase, when it is exported from the nucleus into the cytoplasm, activating RhoA to induce the formation of a mechanically stiff and rounded metaphase cortex. Then, at anaphase, binding to RacGAP1 at the spindle midzone repositions Ect2 to induce local actomyosin ring formation. Ect2 localization therefore defines the stage-specific changes in actin cortex organization critical for accurate cell division.
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Affiliation(s)
- Helen K. Matthews
- MRC Laboratory for Molecular Cell Biology, University College London, Gower St., London WC1E 6BT, UK
| | - Ulysse Delabre
- Department of Physics, Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
- PCC Curie, Institut Curie/CNRS/Université Paris 6 - UMR 168, 26 rue d'Ulm, 75248 Paris, France
| | - Jennifer L. Rohn
- MRC Laboratory for Molecular Cell Biology, University College London, Gower St., London WC1E 6BT, UK
| | - Jochen Guck
- Department of Physics, Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - Patricia Kunda
- MRC Laboratory for Molecular Cell Biology, University College London, Gower St., London WC1E 6BT, UK
| | - Buzz Baum
- MRC Laboratory for Molecular Cell Biology, University College London, Gower St., London WC1E 6BT, UK
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37
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Cellular mechanical properties reflect the differentiation potential of adipose-derived mesenchymal stem cells. Proc Natl Acad Sci U S A 2012; 109:E1523-9. [PMID: 22615348 DOI: 10.1073/pnas.1120349109] [Citation(s) in RCA: 146] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The mechanical properties of adipose-derived stem cell (ASC) clones correlate with their ability to produce tissue-specific metabolites, a finding that has dramatic implications for cell-based regenerative therapies. Autologous ASCs are an attractive cell source due to their immunogenicity and multipotent characteristics. However, for practical applications ASCs must first be purified from other cell types, a critical step which has proven difficult using surface-marker approaches. Alternative enrichment strategies identifying broad categories of tissue-specific cells are necessary for translational applications. One possibility developed in our lab uses single-cell mechanical properties as predictive biomarkers of ASC clonal differentiation capability. Elastic and viscoelastic properties of undifferentiated ASCs were tested via atomic force microscopy and correlated with lineage-specific metabolite production. Cell sorting simulations based on these "mechanical biomarkers" indicated they were predictive of differentiation capability and could be used to enrich for tissue-specific cells, which if implemented could dramatically improve the quality of regenerated tissues.
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38
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Martin M, Müller K, Cadenas C, Hermes M, Zink M, Hengstler JG, Käs JA. ERBB2 overexpression triggers transient high mechanoactivity of breast tumor cells. Cytoskeleton (Hoboken) 2012; 69:267-77. [PMID: 22407943 DOI: 10.1002/cm.21023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2011] [Revised: 12/30/2011] [Accepted: 02/22/2012] [Indexed: 01/15/2023]
Abstract
Biomechanical properties of tumor cells play an important role for the metastatic capacity of cancer. Cellular changes of viscoelastic features are prerequisite for cancer progression since they are essential for proliferation and metastasis. However, only little is known about the way how expression of oncogenes influences these biomechanical properties. To address this aspect we used a breast cancer cell line with inducible expression of an oncogenic version of ERBB2. ERBB2 is known to be correlated with bad prognosis in breast cancer. Cell elasticity was determined by the Optical Stretcher, where suspended cells are deformed by two slightly divergent laser beams. We found that induction of ERBB2 caused remarkable biomechanical alterations of the MCF-7 cells after 24 h: the cells actively contracted in response to mechanical stimuli, a phenomenon known as mechanoactivation. After this period, as the cells became senescent, the mechanoactivity returned to control levels. Time-resolved gene array analysis revealed that mechanoactivation was accompanied by temporal upregulation of 46 cytoskeletal genes. A possible role of these genes in tumor progression was investigated by expression analyses of 766 breast cancer patients. This showed an association of 12 out of these 46 genes with increased risk of metastasis. Our results demonstrate that overexpression of ERBB2 causes mechanoactivation of tumor cells, which may enhance tumor cell motility fostering distant metastasis.
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Affiliation(s)
- Mireille Martin
- Department of Diagnostic and Interventional Radiology, University Hospital Leipzig, and University Leipzig, Leipzig, Germany.
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39
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Sraj I, Szatmary AC, Desai SA, Marr DWM, Eggleton CD. Erythrocyte deformation in high-throughput optical stretchers. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:041923. [PMID: 22680514 PMCID: PMC3989886 DOI: 10.1103/physreve.85.041923] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Revised: 10/30/2011] [Indexed: 05/21/2023]
Abstract
Optical stretchers can be used to quantify elastic and homeostatic properties of cells. Because they can apply forces to cells without requiring direct contact, they may noninvasively measure mechanical properties related to cell and membrane health. Present-day optical stretchers are, however, limited to measurements on individual stationary cells, limiting throughput. To overcome this limitation and allow study of variations in cell populations, we recently developed and tested a microfluidic chamber that measures optical stretching parameters for erythrocytes under dynamic flowing conditions. The method uses a single linear diode laser bar and permitted measurements at low flow rates and higher throughput. Here, we numerically investigate the feasibility of further increasing the measurement rates of the optical stretcher in parameter domains where hydrodynamic and optical forces are of comparable magnitude. To do this we couple a recently implemented dynamic optical ray-tracing technique with a fluid-structure interaction solver to simulate the deformation of osmotically swollen erythrocytes in fluid flow of variable rate. Our results demonstrate that a detectable steady-state stretch is induced at nominal optical powers and flow rates. In addition, we find that flow rates can be increased significantly with no major effect on net cell stretch showing the feasibility of application of this technique at greatly increased throughputs.
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Affiliation(s)
- Ihab Sraj
- Department of Mechanical Engineering, University of Maryland Baltimore County, Baltimore, Maryland 21250, USA
| | - Alex C. Szatmary
- Department of Mechanical Engineering, University of Maryland Baltimore County, Baltimore, Maryland 21250, USA
| | - Sanjay A. Desai
- The Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Disease, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - David W. M. Marr
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado 80401, USA
| | - Charles D. Eggleton
- Department of Mechanical Engineering, University of Maryland Baltimore County, Baltimore, Maryland 21250, USA
- Corresponding author:
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40
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Stewart MP, Toyoda Y, Hyman AA, Müller DJ. Tracking mechanics and volume of globular cells with atomic force microscopy using a constant-height clamp. Nat Protoc 2012; 7:143-54. [DOI: 10.1038/nprot.2011.434] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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41
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Schulze C, Wetzel F, Kueper T, Malsen A, Muhr G, Jaspers S, Blatt T, Wittern KP, Wenck H, Käs JA. Stiffening of Human Skin Fibroblasts with Age. Clin Plast Surg 2012; 39:9-20. [DOI: 10.1016/j.cps.2011.09.008] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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42
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43
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Contractility dominates adhesive ligand density in regulating cellular de-adhesion and retraction kinetics. Ann Biomed Eng 2010; 39:1163-73. [PMID: 21046466 PMCID: PMC3069333 DOI: 10.1007/s10439-010-0195-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Accepted: 10/17/2010] [Indexed: 01/09/2023]
Abstract
Cells that are enzymatically detached from a solid substrate rapidly round up as the tensile prestress in the cytoskeleton is suddenly unopposed by cell-ECM adhesions. We recently showed that this retraction follows sigmoidal kinetics with time constants that correlate closely with cortical stiffness values. This raises the promising prospect that these de-adhesion measurements may be used for high-throughput screening of cell mechanical properties; however, an important limitation to doing so is the possibility that the retraction kinetics may also be influenced and potentially rate-limited by the time needed to sever matrix adhesions. In this study, we address this open question by separating contributions of contractility and adhesion to cellular de-adhesion and retraction kinetics. We first develop serum-free conditions under which U373 MG glioma cells can be cultured on substrates of fixed fibronectin density without direct matrix contributions from the medium. We show that while spreading area increases with ECM protein density, cortical stiffness and the time constants of retraction do not. Conversely, addition of lysophosphatidic acid (LPA) to stimulate cell contractility strongly speeds retraction, independent of the initial matrix protein density and LPA's contributions to spreading area. All of these trends hold in serum-rich medium commonly used in tissue culture, with the time constants of retraction much more closely tracking cortical stiffness than adhesive ligand density or cell spreading. These results support the use of cellular de-adhesion measurements to track cellular mechanical properties.
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44
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Schulze C, Wetzel F, Kueper T, Malsen A, Muhr G, Jaspers S, Blatt T, Wittern KP, Wenck H, Käs JA. Stiffening of human skin fibroblasts with age. Biophys J 2010; 99:2434-42. [PMID: 20959083 PMCID: PMC2956221 DOI: 10.1016/j.bpj.2010.08.026] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Revised: 08/05/2010] [Accepted: 08/10/2010] [Indexed: 01/09/2023] Open
Abstract
Changes in mechanical properties are an essential characteristic of the aging process of human skin. Previous studies attribute these changes predominantly to the altered collagen and elastin organization and density of the extracellular matrix. Here, we show that individual dermal fibroblasts also exhibit a significant increase in stiffness during aging in vivo. With the laser-based optical cell stretcher we examined the viscoelastic biomechanics of dermal fibroblasts isolated from 14 human donors aged 27 to 80. Increasing age was clearly accompanied by a stiffening of the investigated cells. We found that fibroblasts from old donors exhibited an increase in rigidity of ∼60% with respect to cells of the youngest donors. A FACS analysis of the content of the cytoskeletal polymers shows a shift from monomeric G-actin to polymerized, filamentous F-actin, but no significant changes in the vimentin and microtubule content. The rheological analysis of fibroblast-populated collagen gels demonstrates that cell stiffening directly results in altered viscoelastic properties of the collagen matrix. These results identify a new mechanism that may contribute to the age-related impairment of elastic properties in human skin. The altered mechanical behavior might influence cell functions involving the cytoskeleton, such as contractility, motility, and proliferation, which are essential for reorganization of the extracellular matrix.
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45
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Guck J, Lautenschläger F, Paschke S, Beil M. Critical review: cellular mechanobiology and amoeboid migration. Integr Biol (Camb) 2010; 2:575-83. [PMID: 20871906 DOI: 10.1039/c0ib00050g] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Cell motility is important for tissue homeostasis and plays a central role in various pathologies, notably inflammation and cancer. Research into the critical processes involved in cell migration has so far mostly focused on cell adhesion and proteolytic degradation of the extracellular matrix. However, pharmacological interference with these processes only partially blocks cell motility in vivo. In this review we summarize the arising evidence that the mechanical properties of the cell body have a major role to play in cell motility--especially in a low-adhesion, amoeboid-like migration mode in three-dimensional tissue structures. We summarize the processes determining cell mechanics and discuss relevant measurement technologies including their applications in medical cell biology.
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Affiliation(s)
- Jochen Guck
- Cavendish Laboratory, Department of Physics, University of Cambridge, JJ Thomson Ave, Cambridge CB3 0HE, UK.
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46
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Mauritz JMA, Esposito A, Tiffert T, Skepper JN, Warley A, Yoon YZ, Cicuta P, Lew VL, Guck JR, Kaminski CF. Biophotonic techniques for the study of malaria-infected red blood cells. Med Biol Eng Comput 2010; 48:1055-63. [PMID: 20661776 DOI: 10.1007/s11517-010-0668-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Accepted: 07/11/2010] [Indexed: 12/23/2022]
Abstract
Investigation of the homeostasis of red blood cells upon infection by Plasmodium falciparum poses complex experimental challenges. Changes in red cell shape, volume, protein, and ion balance are difficult to quantify. In this article, we review a wide range of optical techniques for quantitative measurements of critical homeostatic parameters in malaria-infected red blood cells. Fluorescence lifetime imaging and tomographic phase microscopy, quantitative deconvolution microscopy, and X-ray microanalysis, are used to measure haemoglobin concentration, cell volume, and ion contents. Atomic force microscopy is briefly reviewed in the context of these optical methodologies. We also describe how optical tweezers and optical stretchers can be usefully applied to empower basic malaria research to yield diagnostic information on cell compliance changes upon malaria infection. The combined application of these techniques sheds new light on the detailed mechanisms of malaria infection providing potential for new diagnostic or therapeutic approaches.
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Affiliation(s)
- Jakob M A Mauritz
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
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47
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Sraj I, Eggleton CD, Jimenez R, Hoover E, Squier J, Chichester J, Marr DWM. Cell deformation cytometry using diode-bar optical stretchers. JOURNAL OF BIOMEDICAL OPTICS 2010. [PMID: 20799841 DOI: 10.1117/1.3470124.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The measurement of cell elastic parameters using optical forces has great potential as a reagent-free method for cell classification, identification of phenotype, and detection of disease; however, the low throughput associated with the sequential isolation and probing of individual cells has significantly limited its utility and application. We demonstrate a single-beam, high-throughput method where optical forces are applied anisotropically to stretch swollen erythrocytes in microfluidic flow. We also present numerical simulations of model spherical elastic cells subjected to optical forces and show that dual, opposing optical traps are not required and that even a single linear trap can induce cell stretching, greatly simplifying experimental implementation. Last, we demonstrate how the elastic modulus of the cell can be determined from experimental measurements of the equilibrium deformation. This new optical approach has the potential to be readily integrated with other cytometric technologies and, with the capability of measuring cell populations, enabling true mechanical-property-based cell cytometry.
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Affiliation(s)
- Ihab Sraj
- University of Maryland Baltimore County, Department of Mechanical Engineering, Baltimore, Maryland 21250, USA
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48
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Sraj I, Eggleton CD, Jimenez R, Hoover E, Squier J, Chichester J, Marr DWM. Cell deformation cytometry using diode-bar optical stretchers. JOURNAL OF BIOMEDICAL OPTICS 2010; 15:047010. [PMID: 20799841 PMCID: PMC2929263 DOI: 10.1117/1.3470124] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The measurement of cell elastic parameters using optical forces has great potential as a reagent-free method for cell classification, identification of phenotype, and detection of disease; however, the low throughput associated with the sequential isolation and probing of individual cells has significantly limited its utility and application. We demonstrate a single-beam, high-throughput method where optical forces are applied anisotropically to stretch swollen erythrocytes in microfluidic flow. We also present numerical simulations of model spherical elastic cells subjected to optical forces and show that dual, opposing optical traps are not required and that even a single linear trap can induce cell stretching, greatly simplifying experimental implementation. Last, we demonstrate how the elastic modulus of the cell can be determined from experimental measurements of the equilibrium deformation. This new optical approach has the potential to be readily integrated with other cytometric technologies and, with the capability of measuring cell populations, enabling true mechanical-property-based cell cytometry.
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Affiliation(s)
- Ihab Sraj
- University of Maryland Baltimore County, Department of Mechanical Engineering, Baltimore, Maryland 21250, USA
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Kemper B, Langehanenberg P, Höink A, von Bally G, Wottowah F, Schinkinger S, Guck J, Käs J, Bredebusch I, Schnekenburger J, Schütze K. Monitoring of laser micromanipulated optically trapped cells by digital holographic microscopy. JOURNAL OF BIOPHOTONICS 2010; 3:425-431. [PMID: 20533430 DOI: 10.1002/jbio.201000035] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
For a precise manipulation of particles and cells with laser light as well as for the understanding and the control of the underlying processes it is important to visualize and quantify the response of the specimens. Thus, we investigated if digital holographic microscopy (DHM) can be used in combination with microfluidics to observe optically trapped living cells in a minimally invasive fashion during laser micromanipulation. The obtained results demonstrate that DHM multi-focus phase contrast provides label-free quantitative monitoring of optical manipulation with a temporal resolution of a few milliseconds.
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Affiliation(s)
- Björn Kemper
- Center for Biomedical Optics and Photonics, University of Münster, Münster, Germany.
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Ekpenyong AE, Posey CL, Chaput JL, Burkart AK, Marquardt MM, Smith TJ, Nichols MG. Determination of cell elasticity through hybrid ray optics and continuum mechanics modeling of cell deformation in the optical stretcher. APPLIED OPTICS 2009; 48:6344-54. [PMID: 19904335 PMCID: PMC3060047 DOI: 10.1364/ao.48.006344] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The optical stretcher is a dual-beam trap capable of stretching individual cells. Previous studies have used either ray- or wave-optical models to compute the optical pressure on the surface of a spherical cell. We have extended the ray-optics model to account for focusing by the spherical interface and the effects of multiple internal reflections. Simulation results for red-blood cells (RBCs) show that internal reflections can lead to significant perturbation of the deformation, leading to a systematic error in the determination of cellular elasticity. Calibration studies show excellent agreement between the predicted and measured escape force, and RBC stiffness measurements are consistent with literature values. Measurements of the elasticity of murine osteogenic cells reveal that these cells are approximately 5.4 times stiffer than RBCs.
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