Dynamics of stress fiber remodeling

Background

Tissue cells are known to actively sense and respond to physical and mechanical cues of the extracellular environment. At the basis of this mechanism lies the communication between cells and their environment.

This project concentrates on the cytoskeletal actin stress fibers, a dynamic filamentous network that drives the fundamental processes of cell motility and shape determination. To serve these roles, it arranges and remodels itself in response to the changing mechanical micro-environment.

When subjected to uniaxial mechanical load (strain) in a 2D environment, stress fibers (and, consequently, cells) orient away from the loading direction (strain avoidance response). However, when substrate topography dictates alignment of cells along a specific direction (anisotropy, contact guidance), a competition between strain and contact guidance arises. Preliminary results show that contact guidance overrules strain avoidance response in Human vena saphena cells (HVSC) seeded on anisotropic substrates and strained in the same direction of the anisotropy.

Objective and project outline

Objective
The aim of this project is to understand the dynamics of stress fiber remodeling upon strain and contact guidance. For this purpose, you will learn to perform experiments using micron-sized devices and analyze cell response mainly by means of fluorescent microscopy.

Methods and project outline
Experiments will be performed in the cell and tissue engineering lab. HVSC will be seeded on beds of microposts (Figure 1). Upon cell fixation and immunostaining at several time points, fluorescent microscopy will be performed. Quantification of stress fiber orientation will be obtained after image post-processing using a Mathematica Code.