Nanotopography of Titanium Surface Enhances Osteoblasts Differentiation of Human Mesenchymal Stem Cells

Titanium (Ti) is the biomaterial considered the gold standard metal to produce implants for dental purposes. Recent studies have shown the enhanced biological activity achieved with nanotechnology-based surface modifications (Variola et al, 2011). Previous studies of our group have shown that conditioning treatment of Ti with a mixture of H₂SO₄/H₂O₂ generates a nanostructured surface that supports higher bone-like nodule formation in cells derived from newborn rat calvariae (De Oliveira et al, 2007). Based on this, the aim of our study was to analyze the gene expression of key bone markers during differentiation of human mesenchymal stem cells (MSCs) into osteoblasts grown on Ti with nanotopography. Machined Ti discs, 12 mm in diameter, were chemically treated with H₂SO₄/H₂O₂ for 4 hours. Untreated discs were used as control. Human MSCs were obtained from bone marrow of iliac crest under the rules of the Committee of Ethics in Human Research and expanded in growth media until subconfluence. Cells were then subcultured in an osteogenic medium (2x10⁴cells/disc) on both nanostructured and control Ti discs for periods of up to 17 days. At 4, 10 and 17 days the gene expression of key bone markers was analyzed by real-time PCR. The obtained data were compared by Mann-Withney U-test, for independent samples (n=3). Nanoestructured Ti increased (p≤0.05) gene expression of alkaline phosphatase (Alp) at day 4, type I collagen (Col) and osteopontin (Opn) at day 10 (p≤0.05) and Runt-related transcription factor 2 (Runx2), osteocalcin (Oc), Opn and bone morphogenetic protein 4 (Bmp-4) at day 17. In conclusion, our results showed that nanotopography upregulates the gene expression of key bone markers during distinct phases of the osteoblast differentiation of human MSCs compared with untreated discs, suggesting that this surface modification may favor the osseointegration of Ti implants.

Acknowledgements: FAPESP (Grant # 2010/18395-3, 2010/19280-5)

 

References:

Variola F, Brunski J, Orsini G, De Oliveira PT, Wazen R, Nanci A. Nanoscale surface modifications of medically relevant metals: state-of-the art and perspectives. Nanoscale 2011; 3: 335-353.

De Oliveira PT, Zalzal SF, Beloti MM, Rosa AL, Nanci A. Enhancement of in vitro osteogenesis on titanium by chemically produced nanotopography. J Biomed Mater Res A 2007;80:554-564.