Characterization of Actin Filament Networks

Abstract

Changes in the biophysical and biomechanical properties of cells and sub-cellular structures are early indicators of onset and progression of human diseases such as cancer. Cell mechanics, locomotion, metastasis and neoplastic transformation are greatly influenced by the cytoskeleton that is composed of actin microfilaments, intermediate filaments and microtubule biopolymer. Prior work on mechanical characterization of semi flexible networks can be extended to mechanical characterization of cytoskeleton networks. It is observed that disrupting actin networks with drugs may lead to a three-fold decrease in cell elasticity, while depolymerizing microtubules and intermediate filaments with appropriate agents does not have as significant an effect on the cell’s structural strength. Thus, it is imperative to develop a realistic model of actin microfilaments for a meaningful prediction of cell mechanical behavior. In this paper, we investigate the influence of directionality of actin filaments in cytoskeleton networks. Numerical models for characterization of actin cytoskeleton are developed from recorded microscope images. It is observed that the directional vectors of actin microfilaments strongly influence their response to mechanical stimuli. The response of the cell to mechanical stimuli is directly correlated with the direction cosines.