cfaed Seminar Series
cfaed Seminar Series
Claude Holenstein , ETH Zürich, Switzerland
Quantitative Traction Force Microscopy in Two and Three Dimensions
MPI CBG, Seminar Room 2 , Pfotenhauerstraße 108 , 01307 Dresden
The mechanical interaction between a cell and its extracellular environment has become an important aspect in the understanding of underlying behaviors such as adhesion, migration and differentiation. In particular the measurement of cell-generated traction forces with a corresponding method called Traction Force Microscopy (TFM) has emerged as a standard approach to establish a link between the mechanical activity of the cell and the intra- and extracellular signaling processes. However, despite many approaches and advancements in this field, a lack of clarity within the developed results remains. This becomes especially apparent when attempting to resolve adhesion footprints close to the physical limits of light microscopy, where numerical instability and small errors lead to a large divergence in the achievable results. Most studies on cellular traction have been undertaken on cells cultured on two-dimensional flat substrates. While this approach provided a basic understanding of mechanical signaling, the physiological relevance to in-vivo situations, where cells are found in three dimensional matrices, remains unclear.
We recently developed a simulation and calibration framework able to generate artificial traction image sets that can be used to develop, quantify and improve techniques for traction force reconstruction in two and three dimensions. Using a whole range of simulated experimental and numerical parameters, we could show that the tracking of the fiducial markers is a critical bottleneck within most TFM approaches. Moreover, this influence can be alleviated by a careful design of the experiments and by using tracking algorithms based on optical flow. This findings have been successfully employed to a range of TFM experiments in 2D. Our current goal is to establish an accurate process, both experimentally and computationally, to perform TFM of cells growing in three dimensional hydrogels. However, dealing with the increased dimensionality of the process resulted in a number of challenging problems, ranging from the experimental optimization of the 3D cell culture and volume microscopy to the increased difficulty to solve the elasticity equations. Here we present our current endeavors and results in this field and provide potential links for collaboration.
Everybody is very welcome!