The response of osteoblast-like SaOS-2 cells to modified titanium surfaces

To study the effects of different chemically modified titanium surfaces on the proliferation, differentiation, adhesion, and apoptosis of osteoblast-like SaOS-2 cells.

In this work, six different titanium materials were tested and compared to each other: (1) glazed; (2) unglazed; (3) unglazed and alkali-etched; (4) unglazed, sandblasted, acid- and alkali-etched; (5) unglazed and coated with zirconium nitride; and (6) unglazed, sandblasted, and acid-etched. The production of alkaline phosphatase (ALP), tumor necrosis factor alpha (TNF-α), matrix metalloproteinase-2, and the expression of adhesion proteins (integrin α3β1, vinculin) were evaluated using ELISA. Finally, the apoptosis of cells was analyzed by flow cytometry.

The most significant differences were found for unglazed sandblasted acid- and alkali-etched titanium discs compared with unglazed titanium discs. The production of TNF-α was decreased after 24 hours, as was the production of ALP after 72 hours. In contrast, the expression of integrin α3β1 was increased after 6 hours. None of the titanium discs showed an apoptotic effect on cells.

This study has shown that physical surface treatments (such as surface roughness) play a more important role than chemical modifications. Generally, chemical modifications such as acid- and alkali-etching can affect the wettability of titanium surfaces, making a surface hydrophilic or hydrophobic according to the modification. The cell attachment is better on hydrophilic surfaces, while hydrophilic surfaces may slightly decrease the expression of ALP activity.