Effects of mechanical stress and scaffold material on osteogenesis and chondrogenesis

The present study was designed to investigate how mouse bone marrow stromal ST2 cells and rat limb mesenchymal stem cells respond to mechanical stress. Mechanical stress loading culture devices originally developed or commercially available were used to induce quantitative strain to these cells. Differentiation of ST2, estimated by alkaline phosphatase (ALP), was shown to be affected by the amount of the strain. Chondrogenic cell differentiation was enhanced by stretch stimulation through phosphplylation of extracellular-signaling regulated kinases (ERKs). In this study, the effect of synthetic scaffold octacalcium phosphate (OCP) was also determined. OCP implantation enhanced bone regeneration. The results suggest that the differentiation of these skeletal tissue forming cells is under control of the mechanical stresses through the signaling cascade. It is likely that the scaffold plays a role of site scaffolding the cells to assist differentiation.