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

Abstract

Purpose: 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.Methods: 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. Results: 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. Conclusion: 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.

A novel, visible light-induced, rapidly cross-linkable gelatin scaffold for osteochondral tissue engineering

“…We used BMP4 and CBD-BMP4 as growth factors. CBD-BMP4 exhibited stronger and more stable collagen binding activity than did wild-type BMP41318. Because gelatin is a hydrolyzed form of collagen, we hypothesized that CBD-BMP4 may be better retained in gelatin-FA hydrogels than native BMP4.…”

Evaluation of the presence of MMP-2, TIMP-2, BMP2/4, and TGFβ3 in the facial tissue of children with cleft lip and palate

“…In recent studies with animal models it has been proved that BMP-4 can also induce hard tissue regeneration ( 21 , 22 ). In his study Torrecillas-Martínez emphasizes that BMP-4 plays an essential role in bone homeostasis and regeneration after surgical expansion of the maxillary sinus ( 23 ).…”

Taking cues from the extracellular matrix to design bone-mimetic regenerative scaffolds

“…To improve BMP anchoring to collagen-based scaffolds, rBMPs have been engineered with CBDs derived from collagen-binding proteins including von Willebrand factor, fibronectin and others [66,120–122]. CBDs have been incorporated into recombinant BMP2 [60,61,66], BMP3 [120], and BMP4 [121,122].…”

“…CBDs have been incorporated into recombinant BMP2 [60,61,66], BMP3 [120], and BMP4 [121,122]. All of these CBD-BMP fusion proteins, when coupled to collagen carriers, were found to stimulate greater bone formation when compared with scaffolds impregnated with unmodified rBMP.…”

“…All of these CBD-BMP fusion proteins, when coupled to collagen carriers, were found to stimulate greater bone formation when compared with scaffolds impregnated with unmodified rBMP. More specifically, greater osteoinduction was elicited by: (1) CBD-BMP3-collagen scaffolds implanted into rat cranial defects [120]; (2) CBD-BMP4-collagen sponges placed into rabbit femurs [122]; and (3) CBD-BMP2-demineralized bone matrix (which is rich in collagen I) implanted into rabbit mandibular defects [66]. …”