Biomechanical Remodeling of Dental Pulp Stem Cell Differentiation

The therapeutic efficacy and potential of human dental pulp stem cells (hDPSCs) for regeneration of dental pulp tissue requires appropriate characterization and control of intracellular biochemical and biomechanical processes that may ultimately direct the cell’s lineage commitment. The cellular mechanical properties such as elasticity and cytoskeleton organization may play an important role in determining cell fate and differentiation. Objective: To characterize the biomechanical properties of hDPSCs in response to osteogenic soluble factors. Methods: Young’s modulus of live DPSCs derived from adult dental pulps was determined by microindentation elasticity testing using an atomic force microscope. Each cell was indented at several different locations over a 15 × 15 um region, avoiding the cell’s perinuclear region. Intracellular F-Actin organization of differentiated and non-differentiated hDPSCs was immunostained with rhodamine-phalloidin for fluorescent visualization. Results: Elastic modulus of hDPSCs as assessed by AFM measurements increased following osteogenic induction. Differentiating DPSCs demonstrated thick actin bundles or stress fibers. In contrast, undifferentiated DPSCs had fewer actin stress fibers. Conclusions: The Young’s modulus of DPSCs increased as these stem cells were biochemically induced to differentiate to the osteogenic lineage. Unlike our previous results involving characterization of bone marrow-derived mesenchymal stem cell biomechanical properties, formation of actin stress fibers were evident and correlated with the increase in the cell stiffness. Since cell biomechanics is governed by the cytoskeleton, cell membrane, and focal adhesions, elucidation of the interplay between them appears necessary for tissue engineering dental pulp.  

This work was supported by a NIH/NIDCR grant (DE019514-SBA)