Berlin 2012 – scientific programme

Parts | Days | Selection | Search | Updates | Downloads | Help

BP: Fachverband Biologische Physik

BP 2: Physics of Cells I

BP 2.8: Talk

Monday, March 26, 2012, 11:45–12:00, H 1028

Reconstruction of Cellular Forces During Migration Through Three-Dimensional Collagen Meshworks — •Julian Steinwachs, Claus Metzner, Nadine Lang, Navid Bonakdar, Stefan Münster, and Ben Fabry — Biophysics Group Universität Erlangen-Nürnberg

Reconstituted collagen gels are a widely used substitute of connective tissue to study cell migration in three dimensions. The importance of cellular traction forces needed for the cells to overcome the steric hindrance of the connective tissue is still unknown. We developed a method to quantify cell tractions in a highly nonlinear fibrous biopolymer 3-D network such as collagen. Using confocal reflection microscopy we image the 3-D fiber structure around cells as they migrate through the collagen gels. Cell forces are then relaxed using cytochalasin D, and the relaxed state of the gel is also imaged. Using a fiber pattern matching algorithm, we reconstruct the cell-induced deformation field around every cell. Matrix stresses are computed with a model for the elastic behavior of collagen gels in which the non-affine behavior (buckling, alignment and tautening of fibers) is approximated by a network of nonlinear elements that deform in an affine way. The model parameters are obtained from rheological measurements. We then optimize the cell tractions that best account for the measured deformation field with a least squared optimization routine. If the precise cell contour is unknown, it is still possible to reconstruct the stress field around the cell and to quantify the traction magnitude. Total computation time is less than 5 minutes per cell on an average desktop computer.