Functionalization of titanium implants using a modular system for binding and release of VEGF enhances bone-implant contact in a rodent model.

Aims: To test the immobilization of vascular endothelial growth factor (VEGF(165)) on the surface of titanium implants using DNA oligonucleotide (ODN) anchor strands for the ability to enhance periimplant bone formation. Materials and Methods: DNA oligonucleotides were anchored to the surface of sandblasted acid-etched (SAE) titanium screw implants and were hybridized with complementary strands of ODN conjugated to rhVEGF(165). The implants were tested against blank SAE implants and SAE implants with nano-anchored ODN. The implants were inserted into the tibiae of 36 Sprague-Dawley rats. Primary outcome parameters were bone-implant contact (BIC), amount of new bone formation and periimplant bone density (BD). density after 1, 4 and 13 weeks. Unit of analysis has been the individual implant. Results: Implants with rhVEGF165 hybridized to ODN anchor strands exhibited significantly increased average BIC after 1 month compared to blank implants and implants with anchored ODN strands. Conclusions: It is concluded that rhVEGF(165)immobilized on the surface of titanium implants through nano-anchored oligonucleotide strands can accelerate BIC of sandblasted and etched titanium implants to a certain extent. The radius of effect of the growth factor appears to be limited to tissue immediately adjacent to the implant surface.