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Scientists involved: Tatjana Autenrieth, Stephanie Frank, Dr. A. Greiner, Maria Jäckel, Benjamin Richter, Prof. Dr. Martin Bastmeyer
Funding: Center for Functional Nanostructures (CFN), BioInterfaces Programme of the Helmholtz Society, Landesgraduiertenförderung (LGFG), KIT (FYS)
During recent years it has become clear that cells are not only influenced by biochemical cues but also by
physical aspects like stiffness and geometry of the extracellular environment. These additional factors are
simultaneously sensed on different length scales, ranging from nanoscale assembly processes at single sites
of adhesion to microscale organization of the cytoskeleton. They have a major impact on cell fate and function,
with dramatic consequences for tissue function. Most of our current knowledge on cell behavior and differentiation
is derived primarily from studies on rigid and planar two-dimensional (2D) tissue culture substrates that are
homogeneously coated with biomolecules. There is an increasing demand for in vitro models that capture more
of the relevant complexity present in three-dimensional (3D) tissue scaffolds. In our projects we use various
techniques to functionalize surfaces with biomolecules in a controlled density and a defined geometry.
In addition, we have developed new methods to manufacture complex tailored 3D microstructures as a growth
substrate for various cell types to study the influence of physical aspects on cell behaviour in a manageable
- Project 1: Cell polarization and haptotaxis on micropatterned ECM-gradients
- Project 2: Cell culture in tailored 3D microstructure scaffolds
- Project 3: Mechanical properties of cells and cell nuclei during invasion in 3D scaffolds [FYS]
Project 1: Polarization and haptotaxis on micropatterned fibronectin-gradients in primary fibroblasts
Scientists involved: Tatjana Autenrieth, Stephanie Frank, Dr. A. Greiner, Prof. Dr. Martin Bastmeyer
Cell polarization and migration are essential for the function of multicellular organisms. Directed cell movement
induced by gradients of soluble signalling molecules is a well-studied phenomenon and referred to as chemotaxis.
In contrast, much less is known about cell migration in substrate-bound adhesive protein gradients (haptotaxis).
Haptotactic cell migration on micropatterned gradients
Still frames of a timelapse movie. DIC images and immunostained pictures after fixation are merged.
We use microcontact printing (µCP) to produce discontinuous adhesive fibronectin gradients. Primary chicken
fibroblasts recognize this pattern and migrate uphill the adhesive gradient. This system offers the possibility
to answer basic biological questions: How do cells recognize and read out adhesive gradients? What is the
temporal sequence of intracellular organelle reorientation and remodelling of the cytoskeleton during polarization
and haptotaxis? What are the intracellular signalling mechanisms involved in this process?
Project 2: Cell culture in tailored 3D-microstructure scaffolds
Scientists involved: Dr. A. Greiner, Maria Jäckel, Benjamin Richter, Prof. Dr. Martin Bastmeyer
Our current knowledge on cell behavior and differentiation is primarily derived from studies on rigid and planar
two-dimensional (2D) tissue culture substrates. Cell behavior and differentiation are, however, not only influenced
by biochemical cues but also by physical properties like adhesive geometry, topography, and stiffness of the
three-dimensional (3D) extracellular environment. Therefore, in vitro model systems that capture more of the
complexity present in 3D tissue scaffolds are highly desirable. We realize (in cooperation with the group of
Prof. Dr. Martin Wegener) 3D scaffolds by means of direct laser writing into biocompatible photoresists
(Nanoscribe system). To incorporate in vivo elasticity we also focus on the fabrication of flexible 3D structures
using Ormocer® as photoresist. These elastic 3D scaffolds can be rhythmically deformed by single beating cardiomyocytes.
Calibration with an atomic force microscope in cooperation with the CFN Research Group Dr. Clemens Franz
indicates that cellular forces down to 10-20 nN are detectable with this setup [Klein et al., 2010].
In collaboration with the group of Prof. Dr. Ulrich Schwarz we develop theoretical modelling approaches and
computer simulations to understand the underlying biophysical mechanisms of cell shape in 3D scaffolds.
Project 3: Mechanical properties of cells and cell nuclei during invasion in 3D microstructure
Scientists involved: Prof. Dr. Martin Bastmeyer, Dr. A. Greiner, Maria Jäckel [FYS]
Cell migration plays an important role not only during development, wound healing and immune response, but also
in pathological processes such as tumor metastasis. In this project which is funded by the KIT (FYS), we systematically
investigate different cell types invading 3D scaffolds with different lattice constants, substrate stiffness and
biochemical surface covering. Since nuclear size and nuclear deformability could be limiting cell invasion factors,
we modulate the mechanical properties of the nucleus by siRNA-mediated Lamin-knockdown.
Three-dimensional lattice structures
(A) Scheme of a simple 3D lattice structure. (B) Oblique view of a 3D-reconstructed confocal image stack after
cultivation of BRLs in inelastic protein-coated scaffolds. (C) Growth of BRL-cells in flexible Ormocere®-baskets.
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