Titanium-adhesive vitronectin promotes peri-implant bone formation via cell adhesion acceleration: An experimental...

Osseointegration begins at the initial blood-implant contact; however, titanium-adhesive blood proteins remain incompletely defined. We used a structure-free, nano-smooth titanium substrate (Ra ≈ 0.6 nm) to identify titanium-adhesive blood proteins and determine whether coating such proteins modulates cell adhesion, osteogenic differentiation, and peri-implant bone formation.

Whole blood from Sprague-Dawley rats was seeded on nano-smooth titanium, followed by stringent washing. Adherent proteins were recovered and analyzed using LC-MS/MS and STRING-based bioinformatics screening. Vitronectin was identified as a major titanium-adhesive protein and functionally evaluated using a recombinant protein. Bone marrow stromal cell (BMSC) adhesion, osteogenic gene expression, mineralization, and peri-implant bone formation were assessed in a rat model. Phosphate-buffered saline (PBS)-treated, albumin-coated, and fibronectin-coated titanium surfaces were used as controls.

The vitronectin coating significantly enhanced early BMSC adhesion compared to all control surfaces, whereas fibronectin and albumin demonstrated no effect. Vitronectin did not alter osteogenic gene expression or mineralization in vitro but significantly accelerated peri-implant bone formation in vivo.

Vitronectin exhibits physicochemical affinity for nano-smooth titanium and promotes peri-implant bone formation, primarily by accelerating early cell adhesion rather than by directly stimulating osteogenic differentiation.