We have tried to understand the role of cellular tone (or internal tension mediated
by actin filaments) and interactions with the microenvironment on cellular stiffness. For
this purpose, we compared the apparent elasticity modulus of a 30-element tensegrity
structure with cytoskeleton stiffness measured in subconfluent and confluent adherent cells
by magnetocytometry, assessing the effect of changing cellular tone by treatment with
cytochalasin D. Intracellular and extracellular mechanical interactions were analyzed on the
basis of the non-dimensional relationships between the apparent elasticity modulus of the
tensegrity structure normalized by Young's modulus of the elastic element versus: (i)
element size, (ii) internal tension, and (iii) number of spatially fixed nodes, for small
deformation conditions. Theoretical results and rigidity measurements in adherent cells
consistently showed that higher cellular tone and stronger interdependencies with cellular
environment tend to increase cytoskeleton stiffness. Visualization of the actin lattice
before and after depolymerization by cytochalasin D tended to confirm the geometrical and
mechanical assumptions supported by analysis of the present model.