“Tensegrity and mechanoregulation: from skeleton to cytoskeleton”, Christopher S. Chen and Donald E. Ingber, Children’s Hospital and Harvard Medical School. Osteoarthritis and Cartilage (1999) 7, 81-94.
“Quantitative analysis of the mechanical properties of the cytoplasm and nucleus have confirmed that structural interplay in the cytoskeleton is complex and that the behaviors of these different filament systems are not simply additive. Actin microfilaments form a volume filling gel that can bear compression, but cannot effectively resist external tension and they tear at high tensile strains. The intermediate filament network is itself poor at resisting lateral compression, yet it efficiently resists tension and hardens at high strains.
However, when these two filament systems are combined in living cells, a fiber-reinforced composite material is formed that can provide both load-bearing functions with greater efficiency, just as many biologic tissues with hierarchical structural arrangements. For cells, however, full mechanical responsiveness and structural stability requires the added presence of microtubules to locally resist the inward contraction of the surrounding tensile cytoskeleton and thereby, to impose a pre-stress in this interconnected molecular network.”