PTH coatings on titanium surfaces improved osteogenic integration by increasing expression levels of BMP-2/Runx2/Osterix

The aim of this experiment was to assemble parathyroid hormone (PTH) coatings on titanium surfaces and evaluate the effect on implant osseointegration. PTH was assembled on surfaces of titanium with different layers (5, 7, and 10) using a layer-by-layer assembling technique. The degradation rate of PTH coatings was evaluated by measuring the concentration of PTH release. Surface analysis using X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FSEM), and surface contact angle measurements revealed a multilayer structure and confirmed that PTH layers could be assembled on titanium. Bone mesenchymal stem cells (BMSCs) cultured on the multiple layer coatings displayed significantly higher alkaline phosphatase activity (ALP) on the 7th day. The osteocalcin concentration was increased significantly in the 7-layer and 10-layer groups. Expression of bone morphogenetic protein 2 (BMP-2), runt-related transcription factor 2 (Runx2), and Osterix were up-regulated at day 7 and day 14. This showed that incubation with PTH enhanced cell proliferation to a statistically significant extent compared with the control group. Results of in vivo experiments demonstrated the formation of new bone, bone-implant contact (BIC), and the expressions of BMP-2, Runx2, and Osterix in the PTH-loaded group were enhanced. It was concluded that PTH coatings may have the potential benefit of enhancing implant osseointegration.