Loading‐related reorientation of bone proteoglycan in vivo. Strain memory in bone tissue?

Abstract

The load‐carrying capacity of the skeleton is achieved and maintained as the result of a continued functional stimulus to the cell populations responsible for bone remodeling. Although some bone cells have been assumed to be influenced by the load‐induced changes in strain throughout the matrix, no evidence is available to indicate which cells are susceptible to such strain change or how such transient events provide a sustained influence on cell behaviour. In the present study, we showed that a short period of dynamic loading in vivo affects the orientation of proteoglycan within bone tissue. This reorientation declines only slowly, thus providing a persistent record of the tissue's recent strain history. Such a record has the ability not only to “capture” strain transients but also to “update” and “average” them. In this way, the bone cells could be presented with a sustained and coherent stimulus directly related to dynamic strain transients. These transients are the tissue's principal function variable.