Reduced inflammatory activity of RAW 264.7 macrophages on titania nanotube modified Ti surface

Macrophages play a pivotal role in the hosts response to biomaterials being considered as an essential cell type during both optimal tissue-implant integration and pathologic process of implant failure. Hence, understanding of their cellular activity on biomaterials is important for improving evaluation and design of biomaterials for biomedical applications. In the present study, we have comparatively investigated the interactions of titania nanotubes (78 nm diameter) and commercial pure Ti with RAW 264.7 macrophages in both standard and pro-inflammatory (stimulation with lipopolysaccharide, LPS) culture conditions. In vitro tests showed that TiO2 nanotubes exhibited significantly decreased inflammatory activity of macrophages with respect to cytokine and chemokine gene expression/protein secretion, induction of foreign body giant cells (FBGCs) and nitric oxide (NO) release thereby mitigating the inflammatory response induced by LPS as compared to flat Ti surface. Therefore, our results suggest a novel role of TiO2 nanotubes in modulating macrophage response in biomaterial-associated bacterial infections. Overall, the current study provides new insight into how TiO2 nanotubes can be involved in macrophage activation and supports the great promise of such surface modifications for biomedical applications.