Stretching adherent cells with light
FacultiesFakultät für Naturwissenschaften
InstitutionsInstitut für Experimentelle Physik
In natural science and medicine mechanical properties of cells are important parameters. Over the years, countless techniques to assess all kinds of parameters have been developed for all kinds of cells. The most important ones are: stiffness, creep and relaxation constants . However, the investigation often relies on the interaction of a probe like a cantilever in AFM or of micropipettes in aspiration experiments with the cells. Hence, the measured properties are always those of the joint system cell and probe. In 2001 a new method to trap and stretch cells was published by Guck et al. He demonstrated that it is possible to investigate the mechanical properties of suspended cells in a microfluidic channel with laser light. In this work we present a setup that is capable of stretching adherent cells with light. This is, to the best of our knowledge, the fist method to determine the mechanical properties of adherent cells without having to alter their biochemistry (e.g. by applying trypsin to detach them) or influence the measurement results by interaction of a probe with the cells. A setup for stretching and a method to detect the deformation of the cell have been developed together with the necessary data analysis algorithms. The deformation data are fitted to different kinds of viscoelastic models to describe the behavior of the cells with networks of springs and dashpods. The best models are selected and the properties of 3T3 fibroblasts measured as cultured are compared to latrunculin treated ones. The finding is, that the new technique works well and delivers the expected results. By investigating the behavior of individual parameters, also conclusion about different parts of the cytoskeleton can be drawn. In addition, the new technique proved to be more sensitive and accurate than the well established technique of passive microrheology.
Subject HeadingsMikroskopie [GND]
Viskoelastisches Medium [GND]