Methods for Analyzing Bone Cell Responses to Mechanical Loading Using In Vitro Monolayer and Organ Culture Models

As bone’s primary function is mechanical, it is not surprising that almost all studies using intact bone concern its morphology. Such histomorphometric studies have been used to provide insights into how bone responds, as an organ, to mechanical loading. However, despite the fact that the cellular basis for “sensing” mechanical stimuli or “communicating” their influence to coordinate any loading-induced changes that they engender is not known, studies in intact bone are rarely used to establish the direct links with any changes in bone cell biochemistry. It is also evident that most studies aimed at defining these mechanisms currently use bone cells grown in vitro, and that this has produced rapid advances in our understanding of the factors that might be involved in regulating bone cell responses to loading-induced stimuli. It is clear that such in vitro studies facilitate the final mechanistic deciphering and constitute a useful initial approach. However, it is also evident that they generally take little regard of the influence that might be provided by cell-cell and cell-matrix interactions within a bone’s complex environment and architecture (1 ). It is therefore imperative to attempt to bridge the gap between the cell biology of bone’s response to loading on the one hand and the morphological approach to this same problem on the other.