Concentration- and time-dependent response of human gingival fibroblasts to fibroblast growth factor 2 immobilized on titanium dental implants

Qianli Ma¹*, Wei Wang¹*, Paul K Chu², Shenglin Mei^1,2, Kun Ji³, Lei Jin⁴, Yumei Zhang^1
1Department of Prosthetic Dentistry, School of Stomatology, Fourth Military Medical University, Xi'an, People's Republic of China; ²Department of Physics and Materials Science, City University of Hong Kong, Kowloon, Hong Kong, People's Republic of China; ³Department of Pediatric Dentistry, School of Stomatology, Fourth Military Medical University, Xi'an, People's Republic of China; ⁴Stomatology Department, Jinling Hospital, School of Medicine, Southern Medical University, Nanjing, People's Republic of China

*These authors contributed equally to this work

Background: Titanium (Ti) implants are widely used clinically, but peri-implantitis remains one of the most common and serious complications. Healthy integration between gingival tissue and the implant surface is critical to long-term success in dental implant therapy. The objective of this study was to investigate how different concentrations of immobilized fibroblast growth factor 2 (FGF2) on the titania nanotubular surface influence the response of human gingival fibroblasts (HGFs).
Methods: Pure Ti metal was anodized at 20 V to form a vertically organized titanium dioxide nanotube array on which three concentrations of FGF2 (250 ng/mL, 500 ng/mL, or 1000 ng/mL) were immobilized by repeated lyophilization. Surface topography was observed and FGF2 elution was detected using enzyme-linked immunosorbent assay. The bioactivity changes of dissolvable immobilized FGF2 were measured by methyl-thiazolyl-tetrazolium assay. Behavior of HGFs was evaluated using adhesion and methyl-thiazolyl-tetrazolium bromide assays.
Results: The FGF2 remained for several days on the modified surface on which HGFs were cultured. Over 90% of the dissolvable immobilized FGF2 had been eluted by Day 9, whereas the FGF2 activity was found to diminish gradually from Day 1 to Day 9. The titania nanotubular surface with an optimal preparing concentration (500 ng/mL) of FGF2 immobilization exhibited improved HGF functions such as cellular attachment, proliferation, and extracellular matrix-related gene expression. Moreover, significant bidirectional as well as concentration- and time-dependent bioactivity was observed.
Conclusion: Synergism of the FGF2-impregnated titanium dioxide nanotubular surface revealed good gingival-implant integration, indicating that these materials might have promising applications in dentistry and other biomedical devices.

Keywords: dental implants, titanium dioxide nanotube, fibroblast growth factor 2, extracellular matrix, real-time polymerase chain reaction