Tracking cell migration by cellular force footprint recorded with a mechano-optical biosensor.

Conventional cell migration assays require time-lapse imaging of live cells to trace cell migration paths, consequently demanding cumbersome hardware setup and suffering from low data throughput. In this work, we developed an assay named Tracking Cells by Footprint (TCF) based on a mechano-optical biosensor that irreversibly becomes fluorescent when sensing local cell adhesive force. Cell migration paths are visualized and recorded as fluorescent footprints on glass or elastic substrates coated with such biosensor. From the footprints, cell migration ranges, speeds and persistence are analyzed and quantified without the need of time-lapse imaging. The feasibility of TCF assays was demonstrated with three types of cells with different migratory capabilities. TCF was then applied to evaluating cell motility affected by biochemical or biomechanical cues. The results show that fibroblast motility is reduced by blebbistatin and vinblastine but promoted by bFGF (basic fibroblast growth factor), and the motility correlates with the substrate rigidity. TCF is also compatible with 96-well plates which, combined with static imaging and large-area scanning, provides high data throughput with minimal additional effort.