Osteoblastic and cytokine gene expression of implant‐adherent cells in humans

Abstract

Implant surface topography is a key determinant affecting osteoblastic differentiation and cell-cell signaling of implant-adherent cells. To assess the early osteoinductive and cell-cell signaling events in adherent cells, commercially pure titanium implants (2.2×5mm) with nanotopography (HF-treated TiO2 grit-blasted) were compared with micron-scale topography TiO2 grit-blasted (micron-scale, control) implants in vivo. Six implants (n=3/surface) were placed in 10 systemically healthy subjects and removed by reverse threading at 1, 3, and 7days. Gene expression profiles of adherent cells were interrogated using low-density RT-PCR arrays. Osteoinduction was not observed at day 1 on either surface. At 3days, elevated levels of BMP6, osteopontin, and osterix (OSX) were observed in RNA of cells adherent to both micron-scale and nanotopography surfaces. Both surfaces supported osteoinductive gene expression at 7days; however, modest elevations of most mRNAs and significantly higher OSX mRNA levels were measured for cells adhered to nanotopography implants. Further, chemokine and cytokine profiles including CXCL10, CXCL14, IL-9, IL-22, and TOLLIP were upregulated on nanotopographic surfaces as compared with microtopographic surfaces. Implants with superimposed nanoscale topography generate a greater induction of genes linked to osteogenesis and cell-cell signaling during the early phases of osseointegration.