IADR Abstract Archives
Macrophage Polarization is Regulated by Surface Chemistry and Energy
Objectives: Stem cells and osteoblasts cultured on microstructured/high-energy titanium (Ti) secrete reduced levels of pro-inflammatory cytokines. Recently, titanium-zirconium alloys (TiZr) have been an alternative to Ti implants, and microstructured TiZr have shown similar effects on stem cells and osteoblasts. However, little is known about the surface effect on immune cells. Immune cells such as macrophages are among the first cells to interact with the implant surface and may create a microenvironment that favors osseointegration or rejection. The aim of this study was to determine the effects of surface energy and chemistry on macrophage polarization to pro-inflammatory (M1) or anti-inflammatory (M2) phenotypes.
Methods: Primary macrophages were isolated from C57BL/6 mice under VCU IACUC approval. Two experiments were performed. (1) To assess the role of surface energy, macrophages were cultured on tissue culture polystyrene (TCPS), microrough-Ti (SLA, aged modSLA [exposed to air for 3-weeks]), or high-energy/microrough-Ti (modSLA, plasmaSLA); (2) the role of surface chemistry was examined by comparing macrophage response to Ti (Ti-SLA, Ti-modSLA) or TiZr (TiZr-SLA, TiZr-modSLA) substrates. In both experiments, conditioned media were collected and secreted pro-inflammatory (IL1β, IL6, TNFα) and anti-inflammatory (IL4, IL10) cytokines measured and normalized to DNA (n=6 cultures/variable; ANOVA, Bonferroni, p<0.05).
Results: Higher levels of pro-inflammatory cytokines were detected on low-energy surfaces (SLA, aged modSLA, TiSLA, TiZrSLA) in comparison to high-energy surfaces (modSLA, plasmaSLA, Ti-modSLA, and TiZr-modSLA). High surface energy increased production of anti-inflammatory IL4 and IL10, and reduced production of pro-inflammatory IL1β, IL6, and TNFα. Pro-inflammatory cytokines were lower and anti-inflammatory cytokines higher on both TiZr-SLA and TiZr-modSLA when compared to Ti surfaces with similar microstructure and energy.
Conclusions: Microstructured, high-energy surfaces induce anti-inflammatory macrophage polarization and reduce pro-inflammatory cytokine production. This effect is further amplified on microstructured, high-energy TiZr, suggesting these materials may produce a healing microenvironment surrounding the implant site.
Methods: Primary macrophages were isolated from C57BL/6 mice under VCU IACUC approval. Two experiments were performed. (1) To assess the role of surface energy, macrophages were cultured on tissue culture polystyrene (TCPS), microrough-Ti (SLA, aged modSLA [exposed to air for 3-weeks]), or high-energy/microrough-Ti (modSLA, plasmaSLA); (2) the role of surface chemistry was examined by comparing macrophage response to Ti (Ti-SLA, Ti-modSLA) or TiZr (TiZr-SLA, TiZr-modSLA) substrates. In both experiments, conditioned media were collected and secreted pro-inflammatory (IL1β, IL6, TNFα) and anti-inflammatory (IL4, IL10) cytokines measured and normalized to DNA (n=6 cultures/variable; ANOVA, Bonferroni, p<0.05).
Results: Higher levels of pro-inflammatory cytokines were detected on low-energy surfaces (SLA, aged modSLA, TiSLA, TiZrSLA) in comparison to high-energy surfaces (modSLA, plasmaSLA, Ti-modSLA, and TiZr-modSLA). High surface energy increased production of anti-inflammatory IL4 and IL10, and reduced production of pro-inflammatory IL1β, IL6, and TNFα. Pro-inflammatory cytokines were lower and anti-inflammatory cytokines higher on both TiZr-SLA and TiZr-modSLA when compared to Ti surfaces with similar microstructure and energy.
Conclusions: Microstructured, high-energy surfaces induce anti-inflammatory macrophage polarization and reduce pro-inflammatory cytokine production. This effect is further amplified on microstructured, high-energy TiZr, suggesting these materials may produce a healing microenvironment surrounding the implant site.