Mechanoresponsiveness of human adipose stem cells on nanocomposite and micro-hybrid composite

Resin‐based composites are used for bone repair applications and comprise resin matrix and different sized filler particles. Nanometer‐sized filler particles improve composite's mechanical properties compared with micrometer‐sized filler particles, but whether differences exist in the biological response to these composites is unknown. Natural bone comprises a nanocomposite structure, and nanoscale interactions with extracellular matrix components influence stem cell differentiation. Therefore we hypothesized that nanometer‐sized filler particles in resin‐based composites enhance osteogenic differentiation of stem cells showing a more bone cell‐like response to mechanical loading compared with micrometer‐sized filler particles. Pulsating fluid flow (PFF; 5 Hz, mean shear stress: 0.7 Pa; 1 h) rapidly, within 5 min, increased nitric oxide production in human adipose stem cells (hASCs) on nanocomposite, but not on micro‐hybrid composite. PFF increased RUNX2 expression in hASCs on micro‐hybrid composite, but not on nanocomposite after 2 h post‐incubation. PFF did not affect mean cell orientation and shape index of hASCs on both composites. In conclusion, the PFF‐increased nitric oxide production in hASCs on nanocomposite, and increased osteogenic differentiation of hASCs on micro‐hybrid composite suggest different responses to mechanical loading of hASCs on composite with nanometer‐sized and micrometer‐sized filler particles. This might have important implications for bone tissue engineering.