Enhanced in vivo osteogenesis by nanocarrier-fused bone morphogenetic protein-4

• Published in: International journal of nanomedicine 2013-01, Vol.8 (1), p.1349-1360
• Main Authors: Shiozaki, Yasuyuki, Kitajima, Takashi, Mazaki, Tetsuro, Yoshida, Aki, Tanaka, Masato, Umezawa, Akihiro, Nakamura, Mariko, Yoshida, Yasuhiro, Ito, Yoshihiro, Ozaki, Toshifumi, Matsukawa, Akihiro
• Format: Article
• Language: English
• Subjects: Animals; Bone Morphogenetic Protein 4 - administration & dosage; Bone Morphogenetic Protein 4 - chemistry; Bone Morphogenetic Protein 4 - genetics; Bone Morphogenetic Protein 4 - pharmacology; Bone morphogenetic proteins; Bone regeneration; Bones; Collagen; Collagen - metabolism; Drug Carriers - administration & dosage; Drug Carriers - chemistry; Female; Fibronectins - chemistry; Fibronectins - genetics; Fibronectins - pharmacology; Growth; Growth factors; Health aspects; Histocytochemistry; Humans; Mice; Nanoparticles - administration & dosage; Nanoparticles - chemistry; Original Research; Osteogenesis - drug effects; Physiological aspects; Proteins; Rabbits; Recombinant Fusion Proteins - chemistry; Recombinant Fusion Proteins - pharmacology; Skull - injuries; Tissue engineering; Tissue Engineering - methods; Tissue Scaffolds
• ISSN: 1178-2013; 1176-9114; 1178-2013
• DOI: 10.2147/IJN.S44124

Bone defects and nonunions are major clinical skeletal problems. Growth factors are commonly used to promote bone regeneration; however, the clinical impact is limited because the factors do not last long at a given site. The introduction of tissue engineering aimed to deter the diffusion of these factors is a promising therapeutic strategy. The purpose of the present study was to evaluate the in vivo osteogenic capability of an engineered bone morphogenetic protein-4 (BMP4) fusion protein. BMP4 was fused with a nanosized carrier, collagen-binding domain (CBD), derived from fibronectin. The stability of the CBD-BMP4 fusion protein was examined in vitro and in vivo. Osteogenic effects of CBD-BMP4 were evaluated by computer tomography after intramedullary injection without a collagen-sponge scaffold. Recombinant BMP-4, CBD, or vehicle were used as controls. Expressions of bone-related genes and growth factors were compared among the groups. Osteogenesis induced by CBD-BMP4, BMP4, and CBD was also assessed in a bone-defect model. In vitro, CBD-BMP4 was retained in a collagen gel for at least 7 days while BMP4 alone was released within 3 hours. In vivo, CBD-BMP4 remained at the given site for at least 2 weeks, both with or without a collagen-sponge scaffold, while BMP4 disappeared from the site within 3 days after injection. CBD-BMP4 induced better bone formation than BMP4 did alone, CBD alone, and vehicle after the intramedullary injection into the mouse femur. Bone-related genes and growth factors were expressed at higher levels in CBD-BMP4-treated mice than in all other groups, including BMP4-treated mice. Finally, CBD-BMP4 potentiated more bone formation than did controls, including BMP4 alone, when applied to cranial bone defects without a collagen scaffold. Altogether, nanocarrier-CBD enhanced the retention of BMP4 in the bone, thereby promoting augmented osteogenic responses in the absence of a scaffold. These results suggest that CBD-BMP4 may be clinically useful in facilitating bone formation.