Osteoclastogenic differentiation of human precursor cells over micro- and nanostructured hydroxyapatite topography.

BACKGROUND: Surface topography is a key parameter in bone cells-biomaterials interactions. This study analyzed the behavior of human osteoclast precursor cells cultured over three hydroxyapatite (HA) surfaces ranging from a micro- to nanoscale topography.

METHODS: HA surfaces were prepared with microsized HA particles, at 1300°C (HA1), and with nanosized HA particles at 1000°C (HA2) and 830°C (HA3). Human osteoclast precursors were cultured in the absence or presence of M-SCF and RANKL.

RESULTS: HA surfaces had similar chemical composition, however, HA1 and HA3 presented typical micro- and nanostructured topographies, respectively, and HA2 profile was between those of HA1 and HA3. The decrease on the average grain diameter to the nanoscale range (HA3) was accompanied by an increase in surface area, porosity and hydrophilicity and a decrease in roughness. Compared to HA1 surface, HA3 allowed a lower osteoclastic adhesion, differentiation and function. Differences in the cell response appeared to be associated with the modulation of relevant intracellular signaling pathways.

CONCLUSIONS: The decrease in HA grain size to a biomimetic nanoscale range, appears less attractive to osteoclastic differentiation and function, compared to the HA microsized topography.

GENERAL SIGNIFICANCE: This observation emphasizes the role of surface topography in designing advanced biomaterials for tailored bone cells response in regenerative strategies.