Objective To identify the expression of nerve growth factor (NGF) and its high affinity receptor (tyrosine kinase receptor A, TrkA) during bone induction by recombined human bone morphogenetic protein 2 (rhBMP-2) by immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR) and to discuss the role of NGF on the bone induction of the BMP. Methods Thirty-six ICR mice were divided into the experimental groupand the control group at random. rhBMP-2 /collagen sponge and collagen sponge were implanted into the right thigh muscle pouches of the mice in the experimental group and the control group, respectively. The tissues in the implanted site of the two groups were removed on the 7th, 14th and 21st day after the implantation. Histological, immunohistochemical and RT-PCR analyses were performed to detect osteoinductive effects of rhBMP-2 and the expression of NGF and TrkA. Results Gross observation showed that a solid lump was found in theright thigh in the experimental group on the 7th day and became harder on the 14th and 21st day, which was not found in the control group. rhBMP-2/collagen sponge displayed a potent ability to induce bone formation, while immunostaining for NGF and TrkA was observed in the course of osteoinduction by rhBMP-2. On the 7th day in the experimental group, NGF positive immunostaining reached the peak in thestage of chondrogenesis and there were a large number of cells expressing NGF, including fibroblasts, chondroblasts, chondrocytes, and osteoblasts; then, therewas a decrease in the number of the positivecells and in the intensity of immunostaining on the 14th and 21st day. Staining of TrkA wassimilar to that of NGF. The expression level of the mRNA of NGF during the course of bone induction peaked 7 days after the implantation and then decreased. Conclusion rhBMP-2/collagen is a kind of satisfactory osteoinductive material, and many different kinds of cells induced by rhBMP-2 can express NGF and TrkA, which suggests that NGF may play an important role in the osteogenesis initiated by exogenous BMP through direct and indirect pathways.
OBJECTIVE To improve the osteoinduction of coral and provide a perfect bone graft substitute for clinical bone defects. METHODS By combining coral with collagen and recombinant human bone morphogenetic protein-2(rhBMP-2), coral/collagen/rhBMP-2 composite was obtained. The composite was implanted into the back muscle pouches of mice, and coral/collagen or coral/rhBMP-2 were implanted as control. The osteoinduction of the composite was assessed by histology and image analysis system. RESULTS The chondrocyte differentiation and matrix formation were observed in local sites after one week, lamellar bone with bone marrow were formed after 4 weeks, and coral were absorbed partially. The quantity of osteoinduction was time-related and rhBMP-2 dose-related(P lt; 0.01). Coral/collagen and coral/rhBMP-2 implants did not show any bone or cartilage formation. CONCLUSION The coral/collagen/rhBMP-2 composite possesses a superior osteoinduction and will be a new type of bone substitute to be used in orthopedic and maxillofacial surgery.
Bovine bone morphogenetic proteingelatin-hydroxyapatite (bBMP-G-HA) was prepared and its efficacy in bone repair of the diaphyseal defects of radii of rats was studied. The results suggested that bBMPG-HA was osteogenetic and capable of being resorbed, and might be used clinically as a new substitute for bone graft.