Mechanical changes in human dental pulp stem cells during early odontogenic differentiation.

INTRODUCTION: Cell adhesion and migration in bioactive scaffolds require actin cytoskeleton remodeling and focal adhesion formation. Additionally, human dental pulp stem cells (hDPSCs) undergo several changes in their mechanical properties during odontogenic differentiation. The effect of factors essential for odontogenesis on actin stress fiber elasticity and focal adhesion formation is not known. METHODS: Live hDPSCs cultured in odontogenic media were imaged for cytoskeleton changes using an atomic force microscope. The Young's modulus (kPa) of the cytoskeleton was recorded as a function of culture medium for 10 days. Focal adhesion formation was assessed using immunofluorescence. Cultured hDPSCs were incubated with a monoclonal vinculin antibody, and filamentous actins were visualized using 0.5 μmol/L phalloidin. RESULTS: Cytoskeletal elasticity significantly increased in response to odontogenic media. Both the number and physical size of focal adhesions in hDPSCs also increased. Up-regulation of vinculin expression was evident. The increase in the formation of focal adhesions was consistent with actin remodeling to stress fibers. CONCLUSIONS: Our findings suggest that hDPSCs firmly attach to the glass substrate in response to odontogenic media. Successful regeneration of pulp-dentin tissue using biomimetic scaffolds will likely require cell-extracellular matrix interactions influenced by biochemical induction factors.