A Method for Applying High Cyclic Strain to Focal Adhesions and Measuring the Cell Response

2013 ◽  
Author(s):  
Toshihiko Shiraishi ◽  
Takuya Ohara ◽  
Shin Morishita
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Focal Adhesion ◽  
High Frequency ◽  
Magnetic Particles ◽  
Focal Adhesions ◽  
Cyclic Strain ◽  
Osteoblast Cell ◽  
A Cell ◽  
The Difference

This paper describes a method by which broadband cyclic strain can be applied to focal adhesions of a cell. In recent years, evidence has been growing that focal adhesions act as mechanosensors of cells which convert mechanical force into biomechanical signaling. However, there are no effective methods by which mechanical stimulation with high frequency can be directly applied to each focal adhesion. Here we develop a micropillar substrate embedding micron-sized magnetic particles and enabling the micropillars to be deflected by external magnetic field. The combination of long and short micropillars produces the difference of deflection between them and enables the micropillars to apply strain to a cell. We verified that the micropillars responded to external magnetic field up to at least 25 Hz without phase difference. Using the magnetic micropillar substrate, we observed the cytoskeletal deformation of an osteoblast cell. The findings indicate that the present micro device can be used for investigating mechanosensing systems of a cell.

Response of an Osteoblast to Cyclic Strain at Its Focal Adhesions Using Magnetic Micropillars

2012 ◽  
Author(s):  
Toshihiko Shiraishi ◽  
Takuya Ohara ◽  
Shin Morishita ◽  
Ryohei Takeuchi
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Focal Adhesion ◽  
Mechanical Stimulation ◽  
Magnetic Particles ◽  
Focal Adhesions ◽  
Cyclic Strain ◽  
Osteoblast Cell ◽  
A Cell ◽  
The Difference

This paper describes a micro device which applies cyclic strain to focal adhesions of a cell. In recent years, evidence has been growing that focal adhesions act as mechanosensors of cells which convert mechanical force into biomechanical signaling. However, there are no effective micro devices which can directly apply mechanical stimulation to each focal adhesion. Here we develop a micropillar substrate embedding micron-sized magnetic particles and enabling the micropillars to be deflected by external magnetic field. The combination of long and short micropillars produces the difference of deflection between them and enables the micropillars to apply strain to a cell. The long pillars were periodically deflected at the amplitude of approximately 1.4 μm whereas most of short pillars were not deflected. Using the magnetic micropillar substrate, we observed the deformation of an osteoblast cell at its focal adhesions. The findings indicate that the present micro device can be used for investigating mechanosensing systems of a cell.

Cell Response to Cyclic Strain at Focal Adhesions

2016 ◽  
Author(s):  
Toshihiko Shiraishi ◽  
Tomohiro Fukuno
Keyword(s):  
Focal Adhesion ◽  
Mechanical Vibration ◽  
Focal Adhesions ◽  
Traction Force ◽  
Cyclic Strain ◽  
Macromolecular Assemblies ◽  
Migration Direction ◽  
A Cell ◽  
Sense And Respond ◽  
The Relationship

Cells are known to sense and respond to mechanical stimulations. The fact shows that there are some cellular mechanosensors for mechanical stimulations. One of the candidates of the mechanosensors is focal adhesions which are large macromolecular assemblies via which mechanical force and regulatory signals may be transmitted between the extracellular matrix and an interacting cell. Although it is quite important to clarify the mechanism of sensing and responding to the mechanical vibration via focal adhesions, there was no micro device applying time-varied mechanical loading to a single focal adhesion of the order of a micrometer. In order to solve the challenging issue, we developed a magnetic micropillar substrate which is able to apply cyclic strain to focal adhesions of a cell. Using the substrate, we investigated how a single osteoblast-like cell changed the direction of migration on micropillars cyclically deflected at 5 Hz and revealed the relationship between the cell migration and the traction force. The experimental results indicate that a cell may sense the cyclic strain and reduce the traction force which is not enough to move the cell body forward leading to changing the migration direction toward the place without cyclic strain.

Effects of Cyclic Strain at Focal Adhesions on Migration of an Osteoblast

2015 ◽  
Author(s):  
Tomohiro Fukuno ◽  
Toshihiko Shiraishi
Keyword(s):  
Magnetic Particles ◽  
Protein Structures ◽  
Focal Adhesions ◽  
Cyclic Strain ◽  
Time Lapse ◽  
Mechanical Forces ◽  
Osteoblast Cell ◽  
Frequency Range ◽  
Cellular Mechanisms ◽  
Biochemical Signals

Cells respond to not only biochemical signals but also mechanical forces, which indicates that cells have some mechanosensors that convert mechanical forces into biochemical signals. According to recent reports, one of the candidates of the mechanosensors is focal adhesions that form multi-protein structures having mechanical links between intracellular cytoskeletons and extracellular matrices. Since the cellular mechanisms of sensing and responding to the mechanical stimulations at focal adhesions have not been clarified yet, we developed a micropillar substrate embedding micron-sized magnetic particles and enabling the micropillars to be cyclically deflected by a time-varied magnetic field. Using the magnetic micropillars, here we apply cyclic strain of some frequencies to a single osteoblast cell through focal adhesions and track cell migration with time-lapse observation to understand how the cell senses and responds to cyclic strain. Our data indicate that the cell may change the direction of migration to move away from the micropillar cyclically deflected in the frequency range from 0.1 to 50 Hz.

scholarly journals Tunable Adhesion of a Bio-Inspired Micropillar Arrayed Surface Actuated by a Magnetic Field

2018 ◽  
Vol 86 (1) ◽  
Author(s):  
Xingji Li ◽  
Zhilong Peng ◽  
Yazheng Yang ◽  
Shaohua Chen
Keyword(s):  
Magnetic Field ◽  
Applied Magnetic Field ◽  
Magnetic Particles ◽  
Rotation Angle ◽  
Adhesion Force ◽  
Practical Applications ◽  
Section Shape ◽  
Theoretical Predictions ◽  
Large Elastic Deformation ◽  
The Difference

Bio-inspired functional surfaces attract many research interests due to the promising applications. In this paper, tunable adhesion of a bio-inspired micropillar arrayed surface actuated by a magnetic field is investigated theoretically in order to disclose the mechanical mechanism of changeable adhesion and the influencing factors. Each polydimethylsiloxane (PDMS) micropillar reinforced by uniformly distributed magnetic particles is assumed to be a cantilever beam. The beam's large elastic deformation is obtained under an externally magnetic field. Specially, the rotation angle of the pillar's end is predicted, which shows an essential effect on the changeable adhesion of the micropillar arrayed surface. The larger the strength of the applied magnetic field, the larger the rotation angle of the pillar's end will be, yielding a decreasing adhesion force of the micropillar arrayed surface. The difference of adhesion force tuned by the applied magnetic field can be a few orders of magnitude, which leads to controllable adhesion of such a micropillar arrayed surface. Influences of each pillar's cross section shape, size, intervals between neighboring pillars, and the distribution pattern on the adhesion force are further analyzed. The theoretical predictions are qualitatively well consistent with the experimental measurements. The present theoretical results should be helpful not only for the understanding of mechanical mechanism of tunable adhesion of micropillar arrayed surface under a magnetic field but also for further precise and optimal design of such an adhesion-controllable bio-inspired surface in future practical applications.

Study of the Performance of Practical Magneto-Rheological Elastomers

2012 ◽  
Vol 430-432 ◽  
pp. 1979-1983
Author(s):  
Wei Bang Feng ◽  
Xue Yang ◽  
Zhi Qiang Lv
Keyword(s):  
Magnetic Field ◽  
Mechanical Properties ◽  
Mechanical Property ◽  
Magnetic Properties ◽  
External Magnetic Field ◽  
Magnetic Particles ◽  
Poor Performance ◽  
Electrical And Magnetic Properties ◽  
Intelligent Material ◽  
Magneto Rheological

Magneto-rheological elastomer( MR elastomer) is an emerging intelligent material made up of macromolecule polymer and magnetic particles. While a promising wide application it has in the fields of warships vibration controlling for its controllable mechanical, electrical and magnetic properties by external magnetic field, design and application of devices based on it are facing great limitations imposed by its poor performance in mechanical properties and magneto effect. Aiming at developing a practical MR elastomer, a new confecting method was proposed in this paper. Then, following this new method and using a specificly designed solidifying matrix, an amido- polyester MR elastomer was developed with its mechanical property systemically explored.

scholarly journals High Frequency Magnetoimpedance of FeNi/Cu/FeNi Sensitive Elements with Different Geometries

2009 ◽  
Vol 152-153 ◽  
pp. 373-376 ◽  
Author(s):  
Stanislav O. Volchkov ◽  
Andrey V. Svalov ◽  
G.V. Kurlyandskaya
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
External Magnetic Field ◽  
Finite Elements ◽  
Magnetic Anisotropy ◽  
Constant Magnetic Field ◽  
High Frequency ◽  
Complex Impedance ◽  
Rf Sputtering ◽  
Frequency Range

In this work magnetoimpedance (MI) behaviour was studied experimentally for Fe19Ni81(175 nm)/Cu(350 nm)/Fe19Ni81(175 nm) sensitive elements deposited by rf-sputtering. A constant magnetic field was applied in plane of the sandwiches during deposition perpendicular to the Cu-lead in order to induce a magnetic anisotropy. Sandwiches with different width (w) of FeNi parts were obtained. The complex impedance was measured as a function of the external magnetic field for a frequency range of 1 MHz to 700 MHz for MI elements with different geometries. Some of MI experimental data are comparatively analysed with finite elements numerical calculations data. The obtained results can be useful for optimization of the design of miniaturized MI detectors.

scholarly journals Cardiac fibroblasts require focal adhesion kinase for normal proliferation and migration

2009 ◽  
Vol 296 (3) ◽  
pp. H627-H638 ◽  
Author(s):  
Ana Maria Manso ◽  
Seok-Min Kang ◽  
Sergey V. Plotnikov ◽  
Ingo Thievessen ◽  
Jaewon Oh ◽  
...  
Keyword(s):  
Focal Adhesion Kinase ◽  
Focal Adhesion ◽  
Adult Mouse ◽  
Cardiac Fibroblasts ◽  
Focal Adhesions ◽  
Protein Levels ◽  
Tyrosine Kinase 2 ◽  
A Cell ◽  
And Migration ◽  
Proliferation And Migration

Migration and proliferation of cardiac fibroblasts (CFs) play an important role in the myocardial remodeling process. While many factors have been identified that regulate CF growth and migration, less is known about the signaling mechanisms involved in these processes. Here, we utilized Cre-LoxP technology to obtain focal adhesion kinase (FAK)-deficient adult mouse CFs and studied how FAK functioned in modulating cell adhesion, proliferation, and migration of these cells. Treatment of FAKflox/flox CFs with Ad/Cre virus caused over 70% reduction of FAK protein levels within a cell population. FAK-deficient CFs showed no changes in focal adhesions, cell morphology, or protein expression levels of vinculin, talin, or paxillin; proline-rich tyrosine kinase 2 (Pyk2) expression and activity were increased. Knockdown of FAK protein in CFs increased PDGF-BB-induced proliferation, while it reduced PDGF-BB-induced migration. Adhesion to fibronectin was not altered. To distinguish between the function of FAK and Pyk2, FAK function was inhibited via adenoviral-mediated overexpression of the natural FAK inhibitor FAK-related nonkinase (FRNK). Ad/FRNK had no effect on Pyk2 expression, inhibited the PDGF-BB-induced migration, but did not change the PDGF-BB-induced proliferation. FAK deficiency had only modest effects on increasing PDGF-BB activation of p38 and JNK MAPKs, with no alteration in the ERK response vs. control cells. These results demonstrate that FAK is required for the PDGF-BB-induced migratory response of adult mouse CFs and suggest that FAK could play an essential role in the wound-healing response that occurs in numerous cardiac pathologies.

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