  In-vivo, cells are frequently exposed to multiple mechanical stimuli arising
from the extracellular microenvironment, with deep impact on many biological
functions. On the other hand, current methods for mechanobiology do not allow
to easily replicate in-vitro the complex spatio-temporal behavior of such
mechanical signals. Here, we introduce a new platform for studying the
mechanical coupling between the extracellular environment and the nucleus in
living cells, based on active substrates for cell culture made of Fe-coated
polymeric micropillars. Under the action of quasi-static external magnetic
fields, each group of pillars produces synchronous nano-mechanical stimuli at
different points of the cell membrane, thanks to the highly controllable
pillars' deflection. This method enables to perform a new set of experiments
for the investigation of cellular dynamics and mechanotransduction mechanisms
in response to a periodic nano-pinching, with tunable strength and arbitrary
temporal shape. We applied this methodology to NIH3T3 cells, demonstrating how
the nano-mechanical stimulation affects the actin cytoskeleton, nuclear
morphology, H2B core-histone dynamics and MKL transcription-cofactor nuclear to
cytoplasmic translocation.
