Reprogramming cell shape with laser nano-patterning.

Cell shape in vitro can be directed by geometrically defined micropatterned adhesion substrates. However conventional methods are limited by the fixed micropattern design, which cannot recapitulate the dynamic changes of the cell microenvironment. Here, we manipulate the shape of living cells in real time by using a tightly focused pulsed laser to introduce additional geometrically defined adhesion sites. The sub-micrometer resolution of the laser patterning allowed us to identify the critical distances between cell adhesion sites required for cell shape extension and contraction. This easy-to-handle method allows the precise control of specific actin-based structures that regulate cell architecture. Actin filament bundles or branched meshworks were induced, displaced or removed in response to specific dynamic modifications of the cell adhesion pattern. Isotropic branched actin meshworks could be forced to assemble new stress fibers locally and polarised in response to specific geometrical cues.