The effects of nerve growth factor on endothelial cells seeded on different titanium surfaces

Angiogenesis is critical for peri-implant bone regeneration and osseointegration. Endothelial cells (ECs) play an important role in angiogenesis during the early stage of bone formation. Nerve growth factor (NGF) is also reported to function as an angiogenic growth factor. The effects of NGF on ECs seeded on titanium surfaces are unclear. This study was done to investigate the influence of NGF on peri-implant angiogenesis in vitro and in vivo. We used two different titanium surfaces. ECs seeded on these surfaces were treated with indicated concentrations of NGF or vascular endothelial growth factor (VEGF). Proliferation, differentiation, morphological features, and amounts attached were assessed. Chicken embryo chorioallantoic membrane (CAM) was adopted to evaluate the effect of NGF in vivo. The results showed that NGF could promote EC proliferation on both titanium surfaces (F1d=2.083, P=0.156; F3d=30.857, P=0.0002; F5d=4.440, P=0.041; F7d=11.065, P=0.001). NGF and the SLA surface upregulated mRNA of NGF, TrkA, and p75 expression (FNGF=11.941, P=0.003; FTrkA=28.514, P=0.004; Fp75=7.725, P=0.01). In vivo, the supernatants of the NGF-treated group could promote neovascularization in CAM (F=17.662, P=0.009). This study demonstrated that NGF could enhance EC proliferation, gene expression on different titanium surfaces, and neovascularization in CAM. This provides novel information in relation to the promotion of early dental implant osseointegration.