Dexamethasone and doxycycline functionalized nanoparticles enhance osteogenic properties of titanium surfaces

Objectives: To evaluate the effect of doxycycline and dexamethasone doped nanoparticles covering titanium surfaces, on osteoblasts proliferation and differentiation. Methods: Doxycycline and dexamethasone doped polymeric nanoparticles were applied on titanium discs (TiDoxNPs and Ti-DexNPs). Undoped NPs and uncovered Ti discs were used as control. Human MG-63 osteoblastlike cells were cultured. Osteoblasts proliferation was tested by MTT assay. Alkaline phosphatase activity was analyzed. Differentiation gene expression was assessed by real-time quantitative polymerase chain reaction. Scanning Electron Microscopy was performed to assess osteoblasts morphology. Mean comparisons were conducted by ANOVA and Wilcoxon or Tukey tests (p < 0.05). Results: No differences in osteoblasts proliferation were found. Osteoblasts grown on Ti-DoxNPs significantly increased alkaline phosphatase activity. Doxycycline and dexamethasone nanoparticles produced an over-expression of the main osteogenic proliferative genes (TGF-& beta;1, TGF-& beta;R1 and TGF-& beta;R2). The expression of Runx-2 was up-regulated. The osteogenic proteins (AP, OSX and OPG) were also overexpressed on osteoblasts cultured on Ti-DoxNPs and Ti-DexNPs. The OPG/RANKL ratio was the highest when DoxNPs were present (75-fold increase with respect to the control group). DexNPs also produced a significantly higher OPG/RANKL ratio with respect to the control (20 times higher). Osteoblasts grown on titanium discs were mainly flat and polygonal in shape, with inter-cellular connections. In contrast, osteoblasts cultured on Ti-DoxNPs or Ti-DexNPs were found to be spindle-shaped and had abundant secretions on their surfaces. Significance: DoxNPs and DexNPs were able to stimulate osteoblasts differentiation when applied on titanium surfaces, being considered potential inducers of osteogenic environment when performing regenerative procedures around titanium dental implants.

Automated summary

This study evaluated the effect of doxycycline and dexamethasone doped nanoparticles on osteoblasts proliferation and differentiation when applied on titanium surfaces. The results showed that these nanoparticles promoted osteoblasts differentiation, up-regulated the expression of osteogenic genes, and altered cell morphology. Therefore, using these nanoparticles in regenerative procedures around titanium dental implants could potentially create a favorable osteogenic environment.