Data from: Collagen network strengthening following cyclic tensile loading

The bulk mechanical properties of tissues are highly tuned to the
physiological loads they experience and reflect the hierarchical structure
and mechanical properties of their constituent parts. A thorough
understanding of the processes involved in tissue adaptation is required
to develop multi-scale computational models of tissue remodelling. While
extracellular matrix (ECM) remodelling is partly due to the changing
cellular metabolic activity, there may also be mechanically directed
changes in ECM nano/microscale organization which lead to mechanical
tuning. The thermal and enzymatic stability of collagen, which is the
principal load-bearing biopolymer in vertebrates, have been shown to be
enhanced by force suggesting that collagen has an active role in ECM
mechanical properties. Here, we ask how changes in the mechanical
properties of a collagen-based material are reflected by alterations in
the micro/nanoscale collagen network following cyclic loading.
Surprisingly, we observed significantly higher tensile stiffness and
ultimate tensile strength, roughly analogous to the effect of work
hardening, in the absence of network realignment and alterations to the
fibril area fraction. The data suggest that mechanical loading induces
stabilizing changes internal to the fibrils themselves or in the
fibril–fibril interactions. If such a cell-independent strengthening
effect is operational in vivo, then it would be an important consideration
in any multiscale computational approach to ECM growth and remodelling.