CELLULAR TENSEGRITY MODELS AND CELL-SUBSTRATE INTERACTIONS

Mammalian cells control their shape and function by altering their mechanical properties through structural rearrangements and changes in molecular biochemistry at the nanometer scale. Yet, little is known about the molecular and biophysical basis of cell mechanics. Most of the existing engineering models of cells are ad hoc descriptions based on measurements obtained under particular experimental conditions, and these continuum models usually ignore contributions of subcellular structures and molecular components. More than 20 years ago, we introduced an alternative model of the cell based on tensegrity architecture which proposes that isometric tension in the cytoskeleton is critical for cell shape stability. Key to this model is the concept that this stabilizing tensile “prestress” results from a complementary force balance between multiple, discrete, molecular support elements, including microfilaments, intermediate filaments and microtubules in the cytoskeleton, as well as external adhesions to extracellular matrix and to neighboring cells. In this chapter, we review progress in the area of cellular tensegrity, including development of theoretical formulations of the tensegrity model that have led to multiple a priori predictions relating to both static and dynamic cell mechanical behaviors that have now been confirmed in experimental studies with living cells. We describe how the cytoskeleton and extracellular matrix form a single, tensionally integrated structural system as predicted by tensegrity, and how distinct molecular biopolymers (e.g., microfilaments vs microtubules) may bear either tensile or compressive loads inside the cell. The tensegrity model is also compared and contrasted with other models of cell mechanics. Taken together, these recent theoretical and experimental studies confirm that the cellular tensegrity model is a useful model because it provides a mechanism to link mechanics to structure at the molecular level, in addition to helping to explain how mechanical signals are transduced into biochemical responses within living cells and tissues.