The cell as a material
Authors: K.E. Kasza, A.C.Rowat, J. Liu, T.A. Angelini, C.P. Brangwynne, G.H. Koenderink & D.A. Weitz
Source: Current Opinion in Cell Biology, Vol 19, 101-107, (2007)
Soft Matter key words: rheology, elastic behavior, viscous behavior, prestress
This review paper summarizes the advances made in probing and recording the material properties of cells. Experiments in this field can be divided in two broad categories: the shearing of purified cytoskeletal filament networks and the probing of whole cells. Results indicate that the cell is a viscoelastic material. Rheology of semi-flexible biopolymer networks reveals stress-stiffening behavior: an increase in applied stress increases the network's elastic modulus. This is thought to be a consequence of the 'pulling out' of filament thermal fluctuations at high stress. Although purified filament networks have a linear elasticity much lower than cells, prestressed networks of such filaments display an elasticity similar to that of cells. According to the authors, this suggests that cells themselves are prestressed into a non-linear regime, possibly by molecular motors such as myosin. In the last part of the paper, all this information is integrated into two competing models that account for cell mechanical behavior.