Topographic patterning of 3D cellular environments controls cell movement, termed topotaxis. Here, fundamental investigations into the mechanism of tissue organization are presented.

Using laser-based two-photon polymerization (2PP) defined topographies were created to investigate fundamental processes of cell movement and organization in structured 3D environments.

Micro- and nanostructured surfaces and variations of biomechanical parameters as well as 3D model structures were produced using 2PP and various hydrogel-based precursor materials, including supramolecular squaramide materials and 1,2-dithiolane (DT) monomer and photoswitchable chemistry. Different cell types, also hiPSCs were analyzed microscopically in these 3D systems.

Analysis of cellular movement reveals specific cell reactions. 3D hydrogel objects in the form of highly porous 3D networks of strung together rings, which allow control of the elastic modulus of the structures and stepwise photocrosslinked 1,2-dithiolane coassembled squaramide materials (without photoinitiator) to increase the storage modulus from approximately 200 Pa to >10 kPa, which led to the stepwise decrease in viscoelasticity and plasticity of the supramolecular networks, enabled control of cell movement. Furthermore, it was shown that cells move in a specific topotactic pattern from a high to a low obstacle density.

The results allow conclusions to be drawn about cell migration behavior as well as cell sorting mechanisms in tissue engineering through topotaxis processes.