In vitro osteogenic differentiation enhanced by zirconia coated with nano-layered growth and differentiation factor-5

Zirconia (Zr) is also known as a biocompatible material with favorable mechanical properties as well as low plaque adhesion. In this study, we examined the efficacy of Zr coated with growth and differentiation factor-5 (GDF-5) bonded via click reaction as a substrate to support osteogenic differentiation of MC3T3-E1 cells. Pristine and surface-modified Zr surfaces were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), resulting that GDF-5 was successfully coated to the pristine Zr surface. GDF-5 coated to Zr surfaces was released for 28 days in a sustained manner. New bone formation onto GDF-5 coated Zr (Zr/GDF-5) surface was confirmed by in vitro test including cell proliferation, alkaline phosphatase activity and calcium deposition assays, and in vivo test including real-time polymerase chain reaction (qPCR) assay including osterix (OSX), runt-related transcription factor 2 (Runx 2), COL 1 (type I collagen) and osteocalcin (OC). Cell proliferation, alkaline phosphatase activity, and calcium deposition of MC3T3-E1 cells were significantly enhanced when the cells were cultured on Zr/GDF-5. Additionally, the results of qPCR revealed that genes related with osteogenic differentiation were up regulated when the cells were cultured on Zr/GDF-5. Our findings demonstrate that Zr/GDF-5 could be used as a material for enhancing the efficacy of osteogenic differentiation.