Mechanobiology of bone tissue.

In order to obtain bones that combine a proper resistance against mechanical failure with a minimum use of material, bone mass and its architecture are continuously being adapted to the prevailing mechanical loads. It is currently believed that mechanical adaptation is governed by the osteocytes, which respond to a loading-induced flow of interstitial fluid through the lacuno-canalicular network by producing signaling molecules. An optimal bone architecture and density may thus not only be determined by the intensity and spatial distribution of mechanical stimuli, but also by the mechanoresponsiveness of osteocytes. Bone cells are highly responsive to mechanical stimuli, but the critical components in the load profile are still unclear. Whether different components such as fluid shear, tension or compression may affect cells differently is also not known. Although both tissue strain and fluid shear stress cause cell deformation, these stimuli might excite different signaling pathways related to bone growth and remodeling. In order to define new approaches for bone tissue engineering in which bioartificial organs capable of functional load bearing are created, it is important to use cells responding to the local forces within the tissue, whereby biophysical stimuli need to be optimized to ensure rapid tissue regeneration and strong tissue repair.