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Atomic force microscopy-based microrheology reveals significant differences in the viscoelastic response between malign and benign cell lines.

Rother J, Nöding H, Mey I, Janshoff A - Open Biol (2014)

Bottom Line: Mechanical phenotyping of cells by atomic force microscopy (AFM) was proposed as a novel tool in cancer cell research as cancer cells undergo massive structural changes, comprising remodelling of the cytoskeleton and changes of their adhesive properties.In this work, we focused on the mechanical properties of human breast cell lines with different metastatic potential by AFM-based microrheology experiments.Including also other cell lines from different organs shows that the loss tangent (G″/G') increases generally with the metastatic potential from MCF-10A representing benign cells to highly malignant MDA-MB-231 cells.

View Article: PubMed Central - PubMed

Affiliation: Institute of Physical Chemistry, Tammannstrasse 6, 37077 Göttingen, Germany.

ABSTRACT
Mechanical phenotyping of cells by atomic force microscopy (AFM) was proposed as a novel tool in cancer cell research as cancer cells undergo massive structural changes, comprising remodelling of the cytoskeleton and changes of their adhesive properties. In this work, we focused on the mechanical properties of human breast cell lines with different metastatic potential by AFM-based microrheology experiments. Using this technique, we are not only able to quantify the mechanical properties of living cells in the context of malignancy, but we also obtain a descriptor, namely the loss tangent, which provides model-independent information about the metastatic potential of the cell line. Including also other cell lines from different organs shows that the loss tangent (G″/G') increases generally with the metastatic potential from MCF-10A representing benign cells to highly malignant MDA-MB-231 cells.

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Related in: MedlinePlus

(a) AFM height image of subconfluent epithelial NMuMG cells (contact mode). (b,c) Height image overlaid with the force map data of (b) G′ and (c) G″ at an oscillation frequency of 20 Hz.
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RSOB140046F2: (a) AFM height image of subconfluent epithelial NMuMG cells (contact mode). (b,c) Height image overlaid with the force map data of (b) G′ and (c) G″ at an oscillation frequency of 20 Hz.

Mentions: Spatially resolved microrheological data acquired for nine different cell lines were compared with respect to their malignant potential. Except for fibroblasts, all cell lines were investigated after confluence was reached. Prior to force mapping, the area of interest of each sample was imaged with the AFM to control morphology and confluency of cells. An example of subconfluent NMuMG cells that demonstrates the typical spatial resolution of the microrheological experiment using the AFM is shown in figure 2. The height image (figure 2a) shows two NMuMG cells in close contact to each other with maximal height of 5.5 µm (red area). In the peripheral areas of the cells, the apical membrane has a distance of a few hundred nanometres from the substrate. We assume that the cells in this image reside in a phase shortly after cytokinesis due to the lack of cell–cell contacts and the presence of a small furrow between the cells [18]. Figure 2b and figure 2c show an overlay of the height image and the corresponding storage and loss modules, respectively. The oscillation frequency of the microrheological measurement was set to 20 Hz in this representative image. Notably, at this frequency the values of G′ exceed those of G″. In general, the cells exhibit higher moduli in the peripheral areas, reaching values of more than 50 kPa for G′ compared with only 1–5 kPa in the cells' centre. The moduli in the centre of each cell are lower compared with those in the periphery, but also with values at the interface between the two cells. The high values of G′ at the cell–cell interface can be explained by the presence of a stiff, contractile actomyosin ring that is necessary for the separation of the daughter cells during cytokinesis [19]. The dense network of actin filaments in direct contact with the cell membrane facilitates a higher resistivity against externally applied forces and therefore leads to higher modules.Figure 2.


Atomic force microscopy-based microrheology reveals significant differences in the viscoelastic response between malign and benign cell lines.

Rother J, Nöding H, Mey I, Janshoff A - Open Biol (2014)

(a) AFM height image of subconfluent epithelial NMuMG cells (contact mode). (b,c) Height image overlaid with the force map data of (b) G′ and (c) G″ at an oscillation frequency of 20 Hz.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4042852&req=5

RSOB140046F2: (a) AFM height image of subconfluent epithelial NMuMG cells (contact mode). (b,c) Height image overlaid with the force map data of (b) G′ and (c) G″ at an oscillation frequency of 20 Hz.
Mentions: Spatially resolved microrheological data acquired for nine different cell lines were compared with respect to their malignant potential. Except for fibroblasts, all cell lines were investigated after confluence was reached. Prior to force mapping, the area of interest of each sample was imaged with the AFM to control morphology and confluency of cells. An example of subconfluent NMuMG cells that demonstrates the typical spatial resolution of the microrheological experiment using the AFM is shown in figure 2. The height image (figure 2a) shows two NMuMG cells in close contact to each other with maximal height of 5.5 µm (red area). In the peripheral areas of the cells, the apical membrane has a distance of a few hundred nanometres from the substrate. We assume that the cells in this image reside in a phase shortly after cytokinesis due to the lack of cell–cell contacts and the presence of a small furrow between the cells [18]. Figure 2b and figure 2c show an overlay of the height image and the corresponding storage and loss modules, respectively. The oscillation frequency of the microrheological measurement was set to 20 Hz in this representative image. Notably, at this frequency the values of G′ exceed those of G″. In general, the cells exhibit higher moduli in the peripheral areas, reaching values of more than 50 kPa for G′ compared with only 1–5 kPa in the cells' centre. The moduli in the centre of each cell are lower compared with those in the periphery, but also with values at the interface between the two cells. The high values of G′ at the cell–cell interface can be explained by the presence of a stiff, contractile actomyosin ring that is necessary for the separation of the daughter cells during cytokinesis [19]. The dense network of actin filaments in direct contact with the cell membrane facilitates a higher resistivity against externally applied forces and therefore leads to higher modules.Figure 2.

Bottom Line: Mechanical phenotyping of cells by atomic force microscopy (AFM) was proposed as a novel tool in cancer cell research as cancer cells undergo massive structural changes, comprising remodelling of the cytoskeleton and changes of their adhesive properties.In this work, we focused on the mechanical properties of human breast cell lines with different metastatic potential by AFM-based microrheology experiments.Including also other cell lines from different organs shows that the loss tangent (G″/G') increases generally with the metastatic potential from MCF-10A representing benign cells to highly malignant MDA-MB-231 cells.

View Article: PubMed Central - PubMed

Affiliation: Institute of Physical Chemistry, Tammannstrasse 6, 37077 Göttingen, Germany.

ABSTRACT
Mechanical phenotyping of cells by atomic force microscopy (AFM) was proposed as a novel tool in cancer cell research as cancer cells undergo massive structural changes, comprising remodelling of the cytoskeleton and changes of their adhesive properties. In this work, we focused on the mechanical properties of human breast cell lines with different metastatic potential by AFM-based microrheology experiments. Using this technique, we are not only able to quantify the mechanical properties of living cells in the context of malignancy, but we also obtain a descriptor, namely the loss tangent, which provides model-independent information about the metastatic potential of the cell line. Including also other cell lines from different organs shows that the loss tangent (G″/G') increases generally with the metastatic potential from MCF-10A representing benign cells to highly malignant MDA-MB-231 cells.

Show MeSH
Related in: MedlinePlus