Transforming growth factor β1 immobilized adsorptively on Ti6Al4V and collagen type I coated Ti6Al4V maintains its biological activity

Titanium and titanium alloys are often used for orthopedic and dental implants. Osseointegration of Ti6Al4V may be improved not only by precoating of the surface with extracellular matrix proteins like collagen type I but also by additional immobilization of growth factors. In the present study, transforming growth factor β1 (TGF-β1) which is known as an inducer of collagen synthesis was immobilized adsorptively on uncoated and collagen type I coated Ti6Al4V surfaces. TGF-β1 was found immobilized slightly faster to collagen type I coated than to uncoated Ti6Al4V and released slower from the collagen coated material. Immobilized TGF-β1 is biologically active for at least 3 weeks storage at 4°C. Sterilization by ethylene oxide inactivates immobilized TGF-β1. In osteoblasts cultured on implants with adsorptively immobilized TGF-β1, mRNA level and specific catalytic activity of alkaline phosphatase as well as accumulation of calcium and phosphate were found reduced, whereas procollagen α1(I) mRNA level and the rate of collagen synthesis were increased.