The Cellular Adhesion research group investigates the role of cell attachment in developing bioactive biomaterials. The successful integration of biomaterials into biological systems critically depends on their ability to support cellular adhesion processes adequately. Interactions between the biological system and the biomaterial surface are essential for biocompatibility i.e., the absence of undesirable cellular responses and bioactivity, which involves the induction of tissue-specific regeneration processes. These interfacial interactions between material and tissue substantially influence the functional performance and compatibility of the applied biomaterial.

The physicochemical properties of a biomaterial surface play a key role in modulating cellular responses. Upon implantation, proteins rapidly adsorb to the surface, forming an interactive layer that mediates subsequent cell adhesion. Cells that come into contact with this protein layer begin to spread on the surface a process known as "spreading" crucial for biomaterial integration. Spreading is primarily supported by the reorganization of the actin cytoskeleton. This dynamic network of protein filaments serves several essential functions, i.e., enabling structural adaptation of the cell during spreading, acting as a platform for intracellular signaling, and playing a central role in mechanotransduction-converting mechanical stimuli into biochemical signals. The interactions between the biomaterial surface, the adsorbed proteins, and adhering cells form a complex system whose understanding is fundamental to developing and optimizing biomaterials.

Cell-biomaterial interactions significantly influence key cellular processes such as adhesion, migration, proliferation, and differentiation. Optimizing these interactions allows biomaterials to be effectively used as tools for tissue regeneration. Therefore, a detailed understanding of the underlying cellular mechanisms is essential for developing functional biomaterials:

Cellular Response to Microstructures – A Contribution to Optimizing Implant Surfaces
As part of the DFG Research Training Group 1505 welisa, it was demonstrated that defined microstructures with sharp edges—such as 5 µm micropillars—induce a phagocytosis-like response in human bone cells (osteoblasts). This behavior is interpreted as an active attempt by the cells to adapt to the surface. Sharp-edged microstructures generate locally increased mechanical stress at the cell membrane. In response, the cells actively adapt their morphology by "enclosing" the micropillars to eliminate them and increase the adhesive surface area. These findings contribute significantly to our understanding of cellular responses to surface topographies and can be used to develop optimized implant materials that promote improved cell integration and tissue compatibility. [Link: Staehlke S et al. Biomaterials. 2015; 46: 48-57; doi:10.1016/j.biomaterials.2014.12.016]. [Link: Moerke C et al., J Mater Sci Mater Med. 2017, 28, 171; doi: 10.1007/s10856-017-5982-8].

Influence of Moderately Positively Charged Biomaterial Surfaces on Cellular Functions
In the first funding phase of the Collaborative Research Centre SFB 1270/2 ELAINE, “cell-friendly biomaterial coatings” were systematically characterized. It was shown that material surfaces with a moderately positive surface charge (zeta potential: +1 to +10 mV) positively influence cellular behavior. These surfaces enhanced cell spreading, calcium ion mobilization, membrane integrity, and proliferation. These results emphasize the significance of surface charge as a tunable parameter for directing cellular responses and provide a valuable foundation for developing biofunctional implant materials. [Link: Gruening M et al., Frontiers in Bioengineering and Biotechnology 2020, 8, 1016; doi: 10.3389/fbioe.2020.01016].

Chemical Surface Modification with Amino Groups to Improve Cell Adhesion
The German-French project AMINOCOAT (DFG-ANR) provided essential insights into the role of amino groups on biomaterial surfaces in promoting cell adhesion and enhancing cellular responses. The study revealed that the presence and density of amino groups are crucial for improved cell adhesion, highlighting their central role in developing and optimizing bioactive bone implants. [Link: Seemann S et al., Molecules 2023, 28, 6505; doi.org/10.3390/molecules28186505].