Stimuli-responsive materials: A smart way to study dynamic cell responses

Cells in the body reside within the extracellular matrix (ECM), a three-dimensional environment that not only provides structural support for the cells, but also influences cellular processes, like migration and differentiation. The ECM and the cells continuously engage in a complex and highly dynamic interplay, shaping both the matrix as well as the cellular outcome. To study these dynamic, bidirectional interactions in a systematic manner, the ability to dynamically control cellular environments is highly desirable. Stimuli-responsive materials are a class of materials that have been engineered to respond to external cues, e.g., light, electricity, or magnetic field, and therefore hold fascinating potentials as an ideal experimental platform to introduce changing spatiotemporal signals to cells. Here, we review the state of the art in stimuli-responsive materials and their design strategies, with an emphasis on the dynamic introduction of physical and mechanical cues. The effects of such dynamic stimuli on the responses of living cells are examined on three different levels: cellular phenotypes, intracellular and cytoskeletal changes, and nuclear and epigenetic effects. Finally, we discuss the current challenges and limitations as well as the potential outlooks in exploiting stimuli-responsive biomaterials.