Titanium surface topography alters cell shape and modulates bone morphogenetic protein 2 expression in the J774A.1 macrophage cell line

Abstract

Macrophage cytokine expression significantly affects wound healing. Macrophage secretion of transforming growth factor beta 1 (TGFbeta1) and bone morphogenetic proteins (BMP) may affect osteogenesis at endosseous implant surfaces. The aim of this investigation was to determine the effect of commercially pure titanium (cpTi) substrate topography on adherent macrophage osteogenic and osteoinductive cytokine expression. J774A.1 murine macrophage cell adhesion was examined by scanning electron microscopy, 0-72 h following plating onto polished, machined, and grit-blasted cpTi surfaces. TGFbeta1 and BMP-2 gene expression by adherent macrophages was determined by the reverse transcription polymerase chain reaction. Macrophage adhesion increased with time on all surfaces and spreading increased with increasing surface roughness (polished < machined < grit-blasted). BMP-2 expression was not evident for cells adherent to polished cpTi at 24 h. In contrast, BMP-2 expression occurred at 24 h in cells adherent to machined and grit-blasted cpTi. BMP-2 expression was evident on all surfaces at 72 h and was greatest in grit-blasted titanium adherent cells. Increasing concentrations of cytochalasin B (0-50 microM) inhibited macrophage spreading and reduced BMP-2 mRNA expression, suggesting a relationship between cell shape and BMP-2 expression. This was further characterized using anti-beta1 and anti-beta3 integrin antibodies. The anti-beta1 integrin antibodies inhibited adherent macrophage BMP-2 mRNA expression. Anti-beta3 integrin antibody treatment only modestly reduced BMP-2 mRNA expression. Endosseous implant surface topography induced changes in macrophage shape that were associated with changes in BMP-2 expression in J774A.1 mouse macrophage cell line. This first demonstration of BMP-2 expression by cpTi adherent macrophages suggests that the macrophage may contribute surface-specific osteoinductive signals during bone formation at implanted alloplastic surfaces.

Submicron-scale surface architecture of tricalcium phosphate directs osteogenesis in vitro and in vivo

“…6, p < 0.05), suggesting that these cells can also impact osteogenesis directly in response to osteoinductive surface structure, as others have previously suggested (Fellah et al, 2007). In vitro, inflammatory macrophages secrete osteogenic factors such as oncostatin M (OSM) (Guihard et al, 2012;Nicolaidou et al, 2012) and may also express BMPs (Champagne et al, 2002;Takebe et al, 2003;Honda et al, 2006). In vivo, Omar et al (2011) showed that a titanium screw coated with lipopolysaccharide (LPS) to stimulate classical activation of macrophages resulted in higher bone contact when in orthotopic sites (Omar et al, 2011) though it is unknown what impact classically activated macrophages may have on bone formation in ectopic sites.…”

Influence of surface microstructure and chemistry on osteoinduction and osteoclastogenesis by biphasic calcium phosphate discs

“…However, large doses of BMPs are required to stimulate substantial amounts of de novo bone formation, likely rendering basal levels of BMPs circulating in the blood ineffective in achieving this response (van Baardewijk et al, 2013;Yuan et al, 2010). Alternatively, BMPs or other osteogenic factors may originate from (pre-)osteoclast interactions with microstructured surfaces including CaP (Davison et al, 2014b) and titanium (Takebe et al, 2003). Elevated Ca 2+ levels resulting from osteoclast resorption of a mineralised substrate can also stimulate BMP expression of precursor cells (Barradas et al, 2012;Klar et al, 2013).…”

Systemic and Local Tissue Response to Titanium Corrosion

“…Mag. X400 the material (Anderson et al, 2004;Lu et al, 2002;Solheim et al, 2002;Takebe et al 2003;Xia & Triffitt, 2006). Particles that are smaller than the macrophages themselves (< 10 µm) can be easily phagocytosed.…”