Magnetoactive Nanotopography on Hydrogels for Stimulated Cell Adhesion and Differentiation

Advanced cell culture platforms that vary the biophysical microenvironment are useful tools for mechanobiology studies and for directing the differentiation of adherent cells to therapeutically relevant phenotypes. Herein, the fabrication of magnetoactive nanofiber mats for integration with hydrogels as a platform for dynamic stimulation at the cell-biomaterial interface is demonstrated. Electrospinning is used to form iron oxide-loaded gelatin-based nanofibers that are stabilized and cross-linked to the surface of gelatin methacryloyl hydrogels. The presence of a magnetic field stimulates focal adhesion formation and maturation in adherent adipose-derived stromal cells, with concurrent changes in cell and nuclear morphology. Adding lineage guiding supplements has been shown to complement biophysical cues, providing optimal conditions for differentiation into osteogenic and adipogenic lineages. The presence of nanofibers at the interface is beneficial to both lineages, but stiffening through an applied magnetic field encourages further osteogenesis while inhibiting adipogenesis. The system is further demonstrated with skeletal myoblasts, where nanotopography and stiffening promote the formation of mature multinucleated muscle cells. This magnetoactive nanofiber platform could prove useful in a wide array of mechanically sensitive cell systems for fundamental studies and for cell production, with flexibility for use with virtually any hydrogel cell culture system.