Objectives: This study examined the intracellular ROS level and oxidative DNA damage of osteoblastic cells cultured on UV-treated and untreated titanium surfaces.
Methods: Titanium disks with machined and acid-etched surfaces were prepared. Some disks were treated with UV light for 48 hours. Osteoblastic cells extracted from rat bone-marrow were cultured on titanium disks for 24 hours. Some cultures were treated with hydrogen-peroxide to induce simulative cellular inflammatory reaction. To measure ROS generation, fluorometric and confocal image analytic assays using intracellular oxidation of DCF-DA was performed. The oxidative DNA damage was evaluated by staining 8Hydroxy 2'deoxyguasonine (8OHdG).
Results: The intracellular ROS level was approximately 1.5 times greater for the culture on the acid-etched titanium surface than on the machined surface. The UV-pretreatment of titanium reduced the ROS level by 40-50% for both machined and acid-etched surfaces. The ROS was detected intensively and extensively in the osteoblasts cultured on untreated titanium surfaces with hydrogen peroxide in the medium, whereas the cells on UV-treated titanium surfaces rarely produced ROS even with hydrogen peroxide. The 8OHdG level per cell decreased by 80% on UV-treated titanium surfaces compared to untreated titanium surfaces.
Conclusion: This study revealed that ROS was generated in osteoblasts cultured on titanium and that the acid-etched rougher surface promoted its production and subsequent DNA damage. UV treatment of titanium substantially reduced the ROS production regardless of the surface types, indicating a novel function of UV photoactivated titanium surfaces.