In vivo performance of titanium implants functionalized with eicosapentaenoic acid and UV irradiation

The aim of this study was to design implant surfaces that attach less to bone but at the same time improve osseous healing for use as temporary bone fracture plates. The strategy was to combine the nonadhesive properties of smooth titanium (Ti) surfaces with the differentiative and anti-inflammatory properties of eicosapentaenoic acid (EPA). Machined Ti implant surfaces coated with a layer of EPA, with or without UV irradiation, were characterized by X-ray photoelectron spectroscopy, and their in vivo performance was evaluated in New Zealand White rabbits. The performance of the functionalised implants was analyzed after 10 weeks of healing by mechanical pull-out testing, molecular biology, and histological and microcomputed tomography analysis. The results indicate that surface functionalization with UV light can reduce bone attachment and volumetric bone mineral density in the peri-implant bone tissue. The presence of EPA on the surfaces enhanced this effect further. Gene expression of bone formation markers showed a trend toward higher mRNA levels in all EPA treated groups. The histological analyses demonstrated lower inflammation in the UV-irradiated group and immature bone formation in all the groups. In conclusion, surface functionalization of Ti implants with UV light and EPA could be a biocompatible coating for reduced bone bonding ability of Ti while promoting bone formation.