The effect of calcitonin gene-related peptide functionalized TiO2 nanotubes on osteoblast and osteoclast differentiation in vitro

Abstract

Osteoporosis is a disease that causes an increased risk of bone fracture. Our goal was to enhance the bioactivity and anti-osteoporotic properties of titanium implants by immobilizing calcitonin gene-related peptide (CGRP) onto TiO2 nanotubes through polydopamine film. The response behaviors of osteoblasts and osteoclasts cultured onto unmodified and modified TiO2 nanotube surfaces were evaluated in vitro. Alkaline phosphatase (ALP) activity, mineralization potential and osteogenic marker gene expression (Runx2, ALP, Col I, OPN, OPG and RANKL) indicated that osteoblast differentiation was greater on CGRP modified TiO2 nanotubes than those on other substrate surfaces. Additionally, tartrate-resistant acid phosphatase (TRAP) and osteoclastic-related gene expression (VATPase, MMP9, TRAP and CTSK) showed that osteoclast differentiation was lowest on CGRP modified TiO2 nanotubes. These results indicate that CGRP functionalized TiO2 nanotubes enhance osteoblast differentiation as well as suppress osteoclast resorption. This study provides design modifications of titanium applied as osteoporotic bone implants.