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The immunomodulatory role of monocytes is essential for tissue healing and can influence the osseointegration of implanted materials. Properties such as the surface structure, hydrophilicity, and roughness of the implanted materials can modulate monocyte–macrophage function. In this study, we characterized material-hydrogenated TiO2 nanotubes (H-TNT) with superhydrophilic surfaces to investigate the effect of H-TNT on macrophage polarization and osseointegration. H-TNT were prepared by anodic oxidation and hydrogenation and used in the experimental group, while TNT and smooth pure Ti were employed in the control groups. RAW264.7 cells were selected to observe the immunomodulatory effect of these samples. The cell morphology was observed via scanning electron microscopy, and cytokine expression was detected using an enzyme-linked immunosorbent assay and immunofluorescence staining. After 24 hr of cultivation, the macrophage-conditioned medium was collected and used for indirect coculture with MC3T3-E1 cells. The morphology of MC3T3-E1 cells was observed using fluorescence staining. Cell adhesion and proliferation were measured using the Cell Counting Kit-8 assay. Alkaline phosphatase activity measurement, alizarin red staining, calcium quantification, and reverse transcription polymerase chain reaction were performed to assess the osteogenic differentiation of MC3T3-E1 cells. The results showed that H-TNT promoted the M2-type polarization of macrophages, which in turn influenced the adhesion, proliferation, and osteogenic differentiation of MC3T3-E1 cells. These materials can serve as useful candidates for bone implants because they activate macrophages to produce a favorable osteoimmunomodulatory microenvironment. [ABSTRACT FROM AUTHOR]

Macrophages are attracting increasing attention in promoting implant-mediated osteogenesis by modulating the microenvironment of the implant site. Biomaterial surface properties including topography and wettability regulate macrophage responses to influence tissue repair. The objective of our present study was to investigate the effects of hydrogenated titanium dioxide nanotube surfaces on the immune response of macrophages in vitro. Hydrogenated titanium dioxide nanotubes (TNTs) were synthesized on Ti surfaces by anodic oxidation and hydrogenation to form super-hydrophilic nanotubular surfaces. Macrophages were seeded directly onto three substrates (hydrogenated TNTs (H2-TNTs), air-annealed TNTs, and commercially pure Ti substrates) and grown under standard or lipopolysaccharide-stimulated culture conditions. Cell proliferation and viability were evaluated by Cell Counting Kit-8 and live/dead staining at 24 and 48 h. Secretion and expression of pro- and anti-inflammatory cytokines were evaluated at 24 and 48 h to determine whether the surfaces elicited differential macrophage behaviors. Gene expression of the M1/M2 surface markers of macrophages was analyzed to assess the effect of the H2-TNT surface on macrophage polarization. The results showed that hydrogenation of the TNT surface resulted in a super-hydrophilic substrate, which exhibited markedly improved wettability attributable to the formation of oxygen vacancies in the nanotubes. The H2-TNT group induced a significantly lower macrophage proliferation rate and up-regulated anti-inflammatory cytokines (interleukin-10, bone morphogenetic protein-2, and transforming growth factor-β1) irrespective of lipopolysaccharide stimulation, while alleviating the secretion of pro-inflammatory cytokines (tumor necrosis factor-α, interleukin-6, nitric oxide, and macrophage chemotactic protein-1) induced by lipopolysaccharide. Moreover, the H2-TNT surface elicited up-regulated gene expression of M2 surface markers and down-regulation of M1 surface markers. We concluded that the hydrogenated TNT surface modulated macrophage immune responses, which could be useful in accelerating inflammation resolution and facilitating tissue repair. [ABSTRACT FROM AUTHOR]

Background: Modified titanium substrates with titanium dioxide nanotubes have broad usage as implant surface treatment and as drug- delivery systems. Their performance in most of these applications is highly dependent on there morphology. Macrophage behavior was thought to be regulated by nanostructured titanium which has been considered as a very promising candidates for dental implants. Aim/Hypothesis: To investigate effects of hydrogenated TiO2 nanotubes on macrophage behavior, secretion and expression of pro- inflammatory cytokines and chemokines. Material and Methods: Macrophage- like J744A.1 cells were cultured on three types of Ti surface- hydrogenated TiO2 nanotubes, unmodified TiO2 nanotubes, and Ti substrates (as control) for 4, 24 and 48 hours. Macrophage adhesion and proliferation were assessed using CCK-8 assay. Levels of pro-inflammatory cytokines (TNF- a, IL- 1b and IL- 6) and chemokines (MCP-1 and MIP-1a) secreted into the supernatant were measured using the Cytometric Bead Arrays kit. TNF-a, MCP-1 and MIP- a gene expression were quantitatively analysed by real- time PCR. Results : These show that TiO2 nanotube surfaces, especially hydrogenated TiO2 nanotubes, benefited macrophage adhesion and prolifera-tion, and reduced protein secretion and mRNA expression of pro- inflammatory cytokines and chemokines. Conclusions and Clinical Implications : TiO2 nanotube surfaces, especially hydrogenated TiO2 nanotubes, reduced inflammatory response in vitro, which might induce rapid osseointegration in implants with hydrogenated TiO2 nanotube surfaces in vivo. [ABSTRACT FROM AUTHOR]