Bone cell mechanosensation and mechanotransduction in vivo and in vitro
The exact nature of how bone can detect and communicate the need for bone repair is unknown. It has been shown that cells of the osteoblast lineage (osteoprogenitors, osteoblasts, osteocytes) are capable of transducing mechanical signals into biochemical stimuli. Osteocytes have long been regarded to be the primary mechanosensors in bone, due to their ubiquitous spatial distribution throughout bone and their extensive communication network facilitated by cell processes that extend to other osteocytes and osteoblasts. However, the precise mechanism by which bone cells sense mechanical stimulation is unknown. Dr. McNamara’s research group investigate the mechanosensory complexes different bone cells have in vivo and also seek to distinguish whether they elaborate the same complexes in vitro, or whether in vitro cell culture conditions alter mechanosensation mechanisms. In particular they use a combination of immunohistochemistry with epifluorescent and confocal microscopy, Immunogold Transmission Electron Microscopy on in vivo bone tissue, and in vitro cell culture to identify integrins, primary cilia and adhesion junction based mechanosensors. Our studies strive to determine the effects of mechanical stimulation on MSCs, osteoblasts and osteocytes in vitro in 2D and 3D environments, to distinguish the differences between different mechanical stimulation regimes on the expression of mechanosensitive proteins. The effect of mechanical stimulation on bone cells is quantified by monitoring expression of specific bone proteins, cell morphology and matrix production.