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Efremov YM, Velay-Lizancos M, Weaver CJ, Athamneh AI, Zavattieri PD, Suter DM, Raman A. Anisotropy vs isotropy in living cell indentation with AFM. Sci Rep 2019; 9:5757. [PMID: 30962474 PMCID: PMC6453879 DOI: 10.1038/s41598-019-42077-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 03/18/2019] [Indexed: 12/30/2022] Open
Abstract
The measurement of local mechanical properties of living cells by nano/micro indentation relies on the foundational assumption of locally isotropic cellular deformation. As a consequence of assumed isotropy, the cell membrane and underlying cytoskeleton are expected to locally deform axisymmetrically when indented by a spherical tip. Here, we directly observe the local geometry of deformation of membrane and cytoskeleton of different living adherent cells during nanoindentation with the integrated Atomic Force (AFM) and spinning disk confocal (SDC) microscope. We show that the presence of the perinuclear actin cap (apical stress fibers), such as those encountered in cells subject to physiological forces, causes a strongly non-axisymmetric membrane deformation during indentation reflecting local mechanical anisotropy. In contrast, axisymmetric membrane deformation reflecting mechanical isotropy was found in cells without actin cap: cancerous cells MDA-MB-231, which naturally lack the actin cap, and NIH 3T3 cells in which the actin cap is disrupted by latrunculin A. Careful studies were undertaken to quantify the effect of the live cell fluorescent stains on the measured mechanical properties. Using finite element computations and the numerical analysis, we explored the capability of one of the simplest anisotropic models – transverse isotropy model with three local mechanical parameters (longitudinal and transverse modulus and planar shear modulus) – to capture the observed non-axisymmetric deformation. These results help identifying which cell types are likely to exhibit non-isotropic properties, how to measure and quantify cellular deformation during AFM indentation using live cell stains and SDC, and suggest modelling guidelines to recover quantitative estimates of the mechanical properties of living cells.
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Affiliation(s)
- Yuri M Efremov
- School of Mechanical Engineering, Purdue University, West Lafayette, Indiana, USA.,Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, USA
| | | | - Cory J Weaver
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, USA.,University of South Carolina, Department of Biological Sciences, Jones PSC Building, 712 Main Street, room 517, Columbia, SC, 29208, USA
| | - Ahmad I Athamneh
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, USA.,Department of Biological Sciences, Purdue University, West Lafayette, Indiana, USA
| | - Pablo D Zavattieri
- Lyles School of Civil Engineering, Purdue University, West Lafayette, Indiana, USA
| | - Daniel M Suter
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, USA. .,Department of Biological Sciences, Purdue University, West Lafayette, Indiana, USA. .,Bindley Bioscience Center, Purdue University, West Lafayette, Indiana, USA. .,Purdue Institute for Integrative Neuroscience, West Lafayette, Indiana, USA.
| | - Arvind Raman
- School of Mechanical Engineering, Purdue University, West Lafayette, Indiana, USA. .,Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, USA.
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Gavara N, Chadwick RS. Relationship between cell stiffness and stress fiber amount, assessed by simultaneous atomic force microscopy and live-cell fluorescence imaging. Biomech Model Mechanobiol 2015. [PMID: 26206449 PMCID: PMC4869747 DOI: 10.1007/s10237-015-0706-9] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Actomyosin stress fibers, one of the main components of the cell’s cytoskeleton, provide mechanical stability to adherent cells by applying and transmitting tensile forces onto the extracellular matrix (ECM) at the sites of cell–ECM adhesion. While it is widely accepted that changes in spatial and temporal distribution of stress fibers affect the cell’s mechanical properties, there is no quantitative knowledge on how stress fiber amount and organization directly modulate cell stiffness. We address this key open question by combining atomic force microscopy with simultaneous fluorescence imaging of living cells, and combine for the first time reliable quantitative parameters obtained from both techniques. We show that the amount of myosin and (to a lesser extent) actin assembled in stress fibers directly modulates cell stiffness in adherent mouse fibroblasts (NIH3T3). In addition, the spatial distribution of stress fibers has a second-order modulatory effect. In particular, the presence of either fibers located in the cell periphery, aligned fibers or thicker fibers gives rise to reinforced cell stiffness. Our results provide basic and significant information that will help design optimal protocols to regulate the mechanical properties of adherent cells via pharmacological interventions that alter stress fiber assembly or via micropatterning techniques that restrict stress fiber spatial organization.
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Affiliation(s)
- Núria Gavara
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London, E1 3NS, UK.
| | - Richard S Chadwick
- Auditory Mechanics Section, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Building 10 Rm. 5D49, 10 Center Drive, MSC-1417, Bethesda, MD, 20892, USA
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3
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CHANG CHENGTAO, LIN CHOUCHINGK, JU MINGSHAUNG. MORPHOLOGY AND ULTRASTRUCTURE-RELATED LOCAL MECHANICAL PROPERTIES OF PC-12 CELLS STUDIED BY INTEGRATING ATOMIC FORCE MICROSCOPY AND IMMUNOFLUORESCENCE IMAGING. J MECH MED BIOL 2012. [DOI: 10.1142/s0219519412500327] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A cost-effective method that integrates high-resolution morphology using an atomic force microscope and immunofluorescence imaging for measuring the local mechanical properties of a cell was developed. By considering the normal indentation conditions and the distribution of the underlying cytoskeleton, a criterion for selecting indentation sites was proposed. PC-12 cells cultivated under normal and high D-glucose medium are employed to demonstrate the applicability of the proposed method. The apparent Young's modulus for each indentation site was estimated by fitting the data with a pyramidal punch contact mechanics model. The results showed that the cell bodies cultivated in the high D-glucose medium were higher but their growth cones were shorter than those cultivated in a normal medium. The Young's moduli of the growth cones were positively correlated with the density of the actin filament in the cytoskeleton. The Young's moduli at the growth cone and the nucleus region of cells cultivated in the high D-glucose medium were higher and lower, respectively, than those of the control group. The results demonstrated the integrated method could correlate local mechanical properties and distribution of actin filament of the growth cone of PC-12 cell.
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Affiliation(s)
- CHENG-TAO CHANG
- Department of Mechanical Engineering, National Cheng Kung University, 1 University Road, Tainan 701, Taiwan
| | - CHOU-CHING K. LIN
- Department of Neurology, University Hospital, National Cheng Kung University, 1 University Road, Tainan 701, Taiwan
| | - MING SHAUNG JU
- Department of Mechanical Engineering, National Cheng Kung University, 1 University Road, Tainan 701, Taiwan
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4
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Zimmer CC, Shi L, Shih Y, Li J, Jin L, Lo S, Liu G. F-Actin reassembly during focal adhesion impacts single cell mechanics and nanoscale membrane structure. Sci China Chem 2012. [DOI: 10.1007/s11426-012-4535-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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5
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Mihai C, Bao S, Lai JP, Ghadiali SN, Knoell DL. PTEN inhibition improves wound healing in lung epithelia through changes in cellular mechanics that enhance migration. Am J Physiol Lung Cell Mol Physiol 2011; 302:L287-99. [PMID: 22037358 DOI: 10.1152/ajplung.00037.2011] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The phosphoinositide-3 kinase/Akt pathway is a vital survival axis in lung epithelia. We previously reported that inhibition of phosphatase and tensin homolog deleted on chromosome 10 (PTEN), a major suppressor of this pathway, results in enhanced wound repair following injury. However, the precise cellular and biomechanical mechanisms responsible for increased wound repair during PTEN inhibition are not yet well established. Using primary human lung epithelia and a related lung epithelial cell line, we first determined whether changes in migration or proliferation account for wound closure. Strikingly, we observed that cell migration accounts for the majority of wound recovery following PTEN inhibition in conjunction with activation of the Akt and ERK signaling pathways. We then used fluorescence and atomic force microscopy to investigate how PTEN inhibition alters the cytoskeletal and mechanical properties of the epithelial cell. PTEN inhibition did not significantly alter cytoskeletal structure but did result in large spatial variations in cell stiffness and in particular a decrease in cell stiffness near the wound edge. Biomechanical changes, as well as migration rates, were mediated by both the Akt and ERK pathways. Our results indicate that PTEN inhibition rapidly alters biochemical signaling events that in turn provoke alterations in biomechanical properties that enhance cell migration. Specifically, the reduced stiffness of PTEN-inhibited cells promotes larger deformations, resulting in a more migratory phenotype. We therefore conclude that increased wound closure consequent to PTEN inhibition occurs through enhancement of cell migration that is due to specific changes in the biomechanical properties of the cell.
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Affiliation(s)
- Cosmin Mihai
- Department of Biomedical Engineering, Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, The Ohio State University, Columbus, Ohio 43210, USA
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6
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Reich A, Meurer M, Eckes B, Friedrichs J, Muller DJ. Surface morphology and mechanical properties of fibroblasts from scleroderma patients. J Cell Mol Med 2010; 13:1644-1652. [PMID: 18624756 DOI: 10.1111/j.1582-4934.2008.00401.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Overproduction of extracellular matrix components by fibroblasts plays a key role in the pathogenesis of scleroderma. To investigate whether these functional alterations are accompanied by changes in the mechanical properties and morphology of fibroblast, atomic force microscopy was applied to dermal fibroblasts derived either from scleroderma patients or from healthy donors. No significant morphological differences could be observed among the different cell strains showing long cytoskeleton fibres similar in length and irregularly distributed protrusions on the cell surface. In contrast, significant differences in cellular stiffness of dermal fibroblasts derived from scleroderma lesions were detected. Compared to fibroblasts from healthy donors, diseased cells were characterized by a reduced elastic constant both when the global and local mechanical properties were probed. The altered stiffness of scleroderma fibroblasts may be important in the pathogenesis of the disease as it could lead to the abnormal response of fibroblasts to mechanical stimuli.
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Affiliation(s)
- Adam Reich
- Department of Dermatology, Venereology and Allergology, Wroclaw Medical University, Wroclaw, Poland.,Department of Dermatology, Carl Gustav Carus Medical Faculty, University of Technology, Dresden, Germany.,Biotechnology Center, University of Technology, Dresden, Germany
| | - Michael Meurer
- Department of Dermatology, Carl Gustav Carus Medical Faculty, University of Technology, Dresden, Germany
| | - Beate Eckes
- Department of Dermatology, University of Cologne, Cologne, Germany
| | - Jens Friedrichs
- Biotechnology Center, University of Technology, Dresden, Germany
| | - Daniel J Muller
- Biotechnology Center, University of Technology, Dresden, Germany
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Fels J, Oberleithner H, Kusche-Vihrog K. Ménage à trois: aldosterone, sodium and nitric oxide in vascular endothelium. Biochim Biophys Acta Mol Basis Dis 2010; 1802:1193-202. [PMID: 20302930 DOI: 10.1016/j.bbadis.2010.03.006] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2009] [Revised: 03/10/2010] [Accepted: 03/11/2010] [Indexed: 12/16/2022]
Abstract
Aldosterone, a mineralocorticoid hormone mainly synthesized in the adrenal cortex, has been recognized to be a regulator of cell mechanics. Recent data from a number of laboratories implicate that, besides kidney, the cardiovascular system is an important target for aldosterone. In the endothelium, it promotes the expression of epithelial sodium channels (ENaC) and modifies the morphology of cells in terms of mechanical stiffness, surface area and volume. Additionally, it renders the cells highly sensitive to small changes in extracellular sodium and potassium. In this context, the time course of aldosterone action is pivotal. In the fast (seconds to minutes), non-genomic signalling pathway vascular endothelial cells respond to aldosterone with transient swelling, softening and insertion of ENaC in the apical plasma membrane. In parallel, nitric oxide (NO) is released from the cells. In the long-term (hours), aldosterone has opposite effects: The mechanical stiffness increases, the cells shrink and NO production decreases. This leads to the conclusion that both the physiology and pathophysiology of aldosterone action in the vascular endothelium are closely related. Aldosterone, at concentrations in the physiological range and over limited time periods can stabilize blood pressure and regulate tissue perfusion while chronically high concentrations of this hormone over extended time periods impair sodium homeostasis promoting endothelial dysfunction and the development of tissue fibrosis.
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Affiliation(s)
- Johannes Fels
- Institute of Physiology II, University of Münster, Germany
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8
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Park CY, Tambe D, Alencar AM, Trepat X, Zhou EH, Millet E, Butler JP, Fredberg JJ. Mapping the cytoskeletal prestress. Am J Physiol Cell Physiol 2010; 298:C1245-52. [PMID: 20164383 DOI: 10.1152/ajpcell.00417.2009] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Cell mechanical properties on a whole cell basis have been widely studied, whereas local intracellular variations have been less well characterized and are poorly understood. To fill this gap, here we provide detailed intracellular maps of regional cytoskeleton (CSK) stiffness, loss tangent, and rate of structural rearrangements, as well as their relationships to the underlying regional F-actin density and the local cytoskeletal prestress. In the human airway smooth muscle cell, we used micropatterning to minimize geometric variation. We measured the local cell stiffness and loss tangent with optical magnetic twisting cytometry and the local rate of CSK remodeling with spontaneous displacements of a CSK-bound bead. We also measured traction distributions with traction microscopy and cell geometry with atomic force microscopy. On the basis of these experimental observations, we used finite element methods to map for the first time the regional distribution of intracellular prestress. Compared with the cell center or edges, cell corners were systematically stiffer and more fluidlike and supported higher traction forces, and at the same time had slower remodeling dynamics. Local remodeling dynamics had a close inverse relationship with local cell stiffness. The principal finding, however, is that systematic regional variations of CSK stiffness correlated only poorly with regional F-actin density but strongly and linearly with the regional prestress. Taken together, these findings in the intact cell comprise the most comprehensive characterization to date of regional variations of cytoskeletal mechanical properties and their determinants.
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Affiliation(s)
- Chan Young Park
- Dept. of Environmental Health, Harvard School of Public Health, Boston, MA 02115, USA
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9
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Davidson L, von Dassow M, Zhou J. Multi-scale mechanics from molecules to morphogenesis. Int J Biochem Cell Biol 2009; 41:2147-62. [PMID: 19394436 PMCID: PMC2753763 DOI: 10.1016/j.biocel.2009.04.015] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Revised: 03/31/2009] [Accepted: 04/15/2009] [Indexed: 01/02/2023]
Abstract
Dynamic mechanical processes shape the embryo and organs during development. Little is understood about the basic physics of these processes, what forces are generated, or how tissues resist or guide those forces during morphogenesis. This review offers an outline of some of the basic principles of biomechanics, provides working examples of biomechanical analyses of developing embryos, and reviews the role of structural proteins in establishing and maintaining the mechanical properties of embryonic tissues. Drawing on examples we highlight the importance of investigating mechanics at multiple scales from milliseconds to hours and from individual molecules to whole embryos. Lastly, we pose a series of questions that will need to be addressed if we are to understand the larger integration of molecular and physical mechanical processes during morphogenesis and organogenesis.
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Affiliation(s)
- Lance Davidson
- Department of Bioengineering, University of Pittsburgh, 3501 Fifth Avenue, 5059-BST3, Pittsburgh, PA, USA.
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10
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Sbrana F, Sassoli C, Meacci E, Nosi D, Squecco R, Paternostro F, Tiribilli B, Zecchi-Orlandini S, Francini F, Formigli L. Role for stress fiber contraction in surface tension development and stretch-activated channel regulation in C2C12 myoblasts. Am J Physiol Cell Physiol 2008; 295:C160-72. [DOI: 10.1152/ajpcell.00014.2008] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Membrane-cytoskeleton interaction regulates transmembrane currents through stretch-activated channels (SACs); however, the mechanisms involved have not been tested in living cells. We combined atomic force microscopy, confocal immunofluorescence, and patch-clamp analysis to show that stress fibers (SFs) in C2C12 myoblasts behave as cables that, tensed by myosin II motor, activate SACs by modifying the topography and the viscoelastic (Young's modulus and hysteresis) and electrical passive (membrane capacitance, Cm) properties of the cell surface. Stimulation with sphingosine 1-phosphate to elicit SF formation, the inhibition of Rho-dependent SF formation by Y-27632 and of myosin II-driven SF contraction by blebbistatin, showed that not SF polymerization alone but the generation of tensional forces by SF contraction were involved in the stiffness response of the cell surface. Notably, this event was associated with a significant reduction in the amplitude of the cytoskeleton-mediated corrugations in the cell surface topography, suggesting a contribution of SF contraction to plasma membrane stretching. Moreover, Cm, used as an index of cell surface area, showed a linear inverse relationship with cell stiffness, indicating participation of the actin cytoskeleton in plasma membrane remodeling and the ability of SF formation to cause internalization of plasma membrane patches to reduce Cm and increase membrane tension. SF contraction also increased hysteresis. Together, these data provide the first experimental evidence for a crucial role of SF contraction in SAC activation. The related changes in cell viscosity may prevent SAC from abnormal activation.
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11
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Micropatterning of single endothelial cell shape reveals a tight coupling between nuclear volume in G1 and proliferation. Biophys J 2008; 94:4984-95. [PMID: 18326659 DOI: 10.1529/biophysj.107.116863] [Citation(s) in RCA: 139] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Shape-dependent local differentials in cell proliferation are considered to be a major driving mechanism of structuring processes in vivo, such as embryogenesis, wound healing, and angiogenesis. However, the specific biophysical signaling by which changes in cell shape contribute to cell cycle regulation remains poorly understood. Here, we describe our study of the roles of nuclear volume and cytoskeletal mechanics in mediating shape control of proliferation in single endothelial cells. Micropatterned adhesive islands were used to independently control cell spreading and elongation. We show that, irrespective of elongation, nuclear volume and apparent chromatin decondensation of cells in G1 systematically increased with cell spreading and highly correlated with DNA synthesis (percent of cells in the S phase). In contrast, cell elongation dramatically affected the organization of the actin cytoskeleton, markedly reduced both cytoskeletal stiffness (measured dorsally with atomic force microscopy) and contractility (measured ventrally with traction microscopy), and increased mechanical anisotropy, without affecting either DNA synthesis or nuclear volume. Our results reveal that the nuclear volume in G1 is predictive of the proliferative status of single endothelial cells within a population, whereas cell stiffness and contractility are not. These findings show that the effects of cell mechanics in shape control of proliferation are far more complex than a linear or straightforward relationship. Our data are consistent with a mechanism by which spreading of cells in G1 partially enhances proliferation by inducing nuclear swelling and decreasing chromatin condensation, thereby rendering DNA more accessible to the replication machinery.
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12
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Kasas S, Dietler G. Probing nanomechanical properties from biomolecules to living cells. Pflugers Arch 2008; 456:13-27. [DOI: 10.1007/s00424-008-0448-y] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2008] [Accepted: 01/09/2008] [Indexed: 12/27/2022]
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13
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Kidoaki S, Matsuda T. Shape-engineered vascular endothelial cells: nitric oxide production, cell elasticity, and actin cytoskeletal features. J Biomed Mater Res A 2007; 81:728-35. [PMID: 17212346 DOI: 10.1002/jbm.a.31112] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Single cell shape determines cellular functions. Therefore, control of cell shape is of considerable importance for the tissue engineering field. This study was designed to assess the effect of surface-induced shaping of vascular endothelial cells (ECs) on the intracellular nitric oxide (NO) production level, the cell elasticity, and cytoskeletal (CSK) features on shape-engineered ECs (round, 90, 120 microm diameter; spindle-shaped, 20, 30, 40 microm width) prepared on a photolithographically microprocessed surface. Intracellular NO production was measured using a microscopic spectrometer with diaminofluorescein diacetate probe. Cell elasticity and actin CSK features were analyzed through microindentation measurement and fluorescence observations with fluorescence and atomic force microscopy. Results showed that spindle-shaped cells exhibited lower NO production, higher cell stiffness, and denser actin stress fibers than the round and nonrestrictedly cultured control cells. Relations between cell shape with NO production, cell elasticity, and actin CSK features were discussed.
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Affiliation(s)
- Satoru Kidoaki
- Division of Biomedical Engineering, Graduate School of Medicine, Kyushu University, Fukuoka 812-8582, Japan
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Kidoaki S, Matsuda T. Shape-engineered fibroblasts: cell elasticity and actin cytoskeletal features characterized by fluorescence and atomic force microscopy. J Biomed Mater Res A 2007; 81:803-10. [PMID: 17226810 DOI: 10.1002/jbm.a.31114] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The regulation of cell shape, which determines cell behaviors including adhesion, spreading, migration, and proliferation in an engineered artificial extracellular milieu, is an important task in tissue engineering and in development of functional biomaterials. To deepen the understandings of shape-dependent cell mechanics, the cell elasticity and structural features of the actin cytoskeleton (CSK) were characterized for shape-engineered fibroblasts; round and spindle-shaped cells cultured on photolithographically microprocessed surfaces, employing the cellular microindentation tests and fluorescence observation of actin CSK by the combination of atomic force microscopy (AFM) and fluorescence microscopy (FM). The relationships among cell elasticity, the structural features of actin CSK, and engineered cell shape were analyzed and compared with those of control cells that had been cultured on nonprocessed surfaces (termed naturally extended cells). Results showed that the spindle-shaped cells with sparse or no apical stress fibers (ASFs) exhibited similar stiffness to that of the naturally extended cells with dense ASFs. The elasticity of spindle-shaped cells was affected only slightly by the stress fiber (SF) density, which is in marked contrast to the significant correlation shown between cell elasticity and SF density in naturally extended cells. This result implies that the elasticity of regionally restricted adhesion-surface-induced shape-engineered cells, particularly of highly elongated cells, is affected predominantly by cell shape rather than by structural features of SFs.
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Affiliation(s)
- Satoru Kidoaki
- Division of Biomedical Engineering, Graduate School of Medicine, Kyushu University, Fukuoka 812-8582, Japan
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