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Cell forces

Cell forces are generated by almost every single animal cell and transferred to its environment. They have many different cellular functions, in particular cell adhesion for the purpose of generating morphologies which do not correspond to a spherical shape (to form, for example, epithelia, muscle or brain tissue). Cell forces also enable movement of cells for example during embryogenesis or wound healing as well as selective contraction of muscle. In line with this wide range of biological functions of cell forces, a plethora of force-producing and force-transmitting structures exist. Aim of this research focus is to understand in detail 1) how cell force is generated and transferred to the environment 2) how large the force of the different cell types is and 3) by which specific adhesion structures (see cell adhesion) the force is transferred. Nearly all of these questions lead to highly specific answers with regard to almost every single cell type.

Kraftanalyse und Deformationsfeld

Forces of animal cells (here created by an adhered with GFP-α-actinin transfected heart muscle cell) on elastic substrates lead to its deformation. These deformations can be measured by decorating the substrate with fluorescent microbeads that are tracked via fluorescence microscopy and digital image processing. From these displacements of marker particles forces are calculated. The deformation field is depicted vectorially (left picture, green arrows) and in false-color display (right picture). Calculated cell forces per focal adhesion are indicated by red vectors (left image). The first generalized moment as a measure for the sum of all contracted forces can be seen in the left picture in blue.

In order to analyze cellular forces we have developed elastomer systems on the basis of different silicon rubbers that allow visualization of forces of living cells with high temporal and spatial resolution. Therefore, additional microstructures are transferred into the surfaces of the transparent elastomer substrates. Forces of adherent cells deform the substrates. The forces of single cells can be determined by analyses of displacement of embedded microstructures via image processing and algorithms solving the underlying equations of elastostatics. Depending on the density of microstructures force fields can be resolved up to under 1 μm. This enables the determination of cellular forces on the level of single adhesion structures. As cell force is a compulsory prerequisite for numerous cellular functions which have not been well examined up to now because of technical limitations this analysis permits a fascinating insight into the interplay of cell mechanics and function.

For further questions please contact: Dr. Bernd Hoffmann, Prof. Dr. Rudolf Merkel