Bone Abstracts

Titanium (Ti) surface with nanotopography induces osteoblast differentiation, at least in part, by upregulating the expression of α1/β1 integrins. Thus, we hypothesized that other potential candidates from the integrin signalling pathway may be involved in the osteogenic potential of nanotopography. In this context, the aim of this study was to compare the expression of integrin family members of cells grown on nanotopography with machined surface. Machined Ti discs were treated or not with H2SO4/H2O2 to produce nanotopography and the surfaces were analysed by scanning electron microscopy and optical interferometry. Mesenchymal stem cells (MSCs) from rat bone marrow were obtained under the approval of the Committee of Ethics in Animal Research (#2014.1.796.58.7) cultured on both Ti surfaces for up to 7 days. To confirm the osteogenic potential of the nanotopography, the gene expression of some osteoblast markers was evaluated by real-time PCR at day 7. The expression of a panel of genes involved in the integrin signalling pathway was evaluated by PCR array at day 3. All experiments were done in triplicate (n=3) and the data were compared by t-test (P≤0.05). Ti with nanotopography exhibited a network of nanopits with higher (P=0.002) roughness average compared with machined Ti, which presented a smooth surface. The gene expression of Runx2 (P=0.006), osterix (P=0.017), alkaline phosphatase (P=0.004), osteocalcin (P=0.001) and bone sialoprotein (P=0.001) was higher in cells grown on nanotopography compared with machined Ti surface. The nanotopography induced significant changes (modulation ≥2-fold) in the expression of 12 genes, five integrins and seven members of the focal adhesion kinase signalling pathway (P≤0.05). In conclusion, we have shown that Ti with nanotopography modulates the expression of several genes involved in the integrin signalling pathway at early stages of the culture development, which could be related to the higher osteoblast differentiation induced by this surface.