Recent models in polymer physics and their relevance to cell elasticity

The structural response and internal organization of eukaryotic cells is governed by its cytoskeleton - a highly-organized polymer network extending throughout the cell. Composed of three types of protein filaments - actin filaments, microtubules and intermediate filaments - the cytoskeleton is directly responsible for intra- and intercellular movements as well as cellular shape changes. Hence, the cytoskeleton is a dynamic material, whose architecture and composition reflect cell function and state. This high correlation of cytoskeletal architecture to basic cell functions such as mitosis and transport, has led researchers in the pathology of several diseases, including cancer, to conclude that cytoskeletal changes are key, perhaps even diagnostic, in the progression of these diseases. This, in turn, implies that the change in cell elasticity or structural response due to cytoskeletal change is an important parameter to characterize cells.

There have been many experimetal techniques to characterize eukaryotic cell elasticity. There have also been polymer rheology experiments for the structural characterization of in vitro polymer networks. Our work focusses on relating these two fields, by understanding the results of cell deformation experiments, based on the polymer physics of the cytoskeleton. We have performed detailed theoretical investigations of the structural properties of the actin cytoskeleton and its contribution to cell strength. The ultimate aim of this work is to quantify the contribution of each individual cytoskeletal polymer network to the entire structural response of the cell.