ABSTRACT
@#Bone graft material is not only a simple scaffold frame, but also a material with the potential to induce cells grow and differentiate into osteoblasts. The material with excellent bone induction properties can accelerate the healing of bone defect, thus repair the large area of bone defect successfully. Currently, plenty of researches regarding the bone induction in bone graft material have been reported, how to maximize the material osteoinductive potential, and to take advantage of these biological materials to produce the next generation of innovative biological material, is the current concerns. In this paper, a review is made on the bone induction properties of several kinds of bone substitutes.
ABSTRACT
BACKGROUND:The phenomenon of osteoinduction by biomaterials has been proven in animal experiments. OBJECTIVE:To investigate whether the ability of a biomaterial to initiate bone formation in ectopic implantation sites improves the performance of osteoinductive biomaterial as a scaffold for tissue-engineered bone. METHODS:We compared ectopic bone formation by combining autologous adipose-derived stromal cells with an osteoinductive and a nonosteoinductive biphasic calcium phosphate ceramic to create a tissue engineering construction in the muscle of dogs. Al implants were implanted in the back muscle of 10 adult dogs for 8 weeks and 12 weeks, including osteoinductive biphasic calcium phosphate ceramic+adipose-derived stromal cells (osteoinductive complex group), osteoinductive biphasic calcium phosphate ceramic (osteoinductive broup), nonosteoinductive biphasic calcium phosphate ceramic+adipose-derived stromal cells (nonosteoinductive complex group), and nonosteoinductive biphasic calcium phosphate ceramic (nonosteoinductive group). Micro-CT analysis and histomorphometry were performed to evaluate and quantify ectopic bone formation. RESULTS AND CONCLUSION:Ectopic bone formation was visible in the osteoinductive complex group and osteoinductive group, and the former group was superior to the latter one in quality of new bone (P<0.05). However, there was no ectopic bone formation in the other two groups. Micro-CT results were consistent with the histomorphological detection. These findings indicate that osteoinductive biphasic calcium phosphate ceramic, as a kind of bone tissue engineering scaffold material, has a better osteogenic capacity, while adipose-derived mesenchymal stem cells serve as seed cells to promote the ectopic bone formation.
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PURPOSE: The carrier for the delivery of bone morphogenetic proteins(BMPs) should also serve as a scaffold for new bone growth. In addition, predictable bone formation in terms of the volume and shape should be guaranteed. This study evaluated the ectopic bone formation of recombinant human BMP-2(rhBMP-2) using a micro macroporous biphasic calcium phosphate (MBCP: mixture of betaTCP and HA) block as a carrier in a rat subcutaneous assay model. MATERIALS AND METHODS: Subcutaneous pockets were created on the back of 40 male Sprague-Dawley rats. In the pockets, rhBMP-2/MBCP and MBCP alone were implanted. The blocks were evaluated by histological and histometric parameters after a healing interval of 2 weeks (each 10 rats; MBCP and rhBMP-2/MBCP) or 8 weeks (each 10 rats; MBCP and rhBMP-2/MBCP). RESULTS: The shape and volume of the block was maintained stable over the healing period. No histological bone forming activity was observed in the MBCP alone sites after 2 weeks and there was minimal new bone formation at 8 weeks. In the rhBMP-2/MBCP sites, new bone formation was evident in the macropores of the block. The new bone area at 8 weeks was greater than at 2 weeks. There was a further increase in the quantity of new bone with the more advanced stage of remodeling. CONCLUSIONS: A MBCP block could serve as a carrier system for predictable bone tissue engineering using rhBMPs.
Subject(s)
Animals , Humans , Male , Rats , Bone and Bones , Bone Development , Calcium , Hydroxyapatites , Osteogenesis , Rats, Sprague-Dawley , Subcutaneous TissueABSTRACT
Objective To investigate the effect of nerve growth factor (NGF) on the bone induction of recombinant human bone morphogenetic protein-2 (rhBMP-2) through local application of NGF in the osteoinductive process of BMP. Methods Thirty-six ICR mice were divided into the experimental group and control group at random, and rhBMP-2/collagen composite was implanted into the right thigh muscle pouch of each group. NGF or vehicle was daily injected into the implanted sites of BMP, respectively, for 7 days starting from the third day after surgery. At d10, d20 and d30 after implantation, new bone formation was measured radiographically, biochemically and histologically to compare the osteogenetic capacity of the two groups. Results In both groups, new bone formation was found at d10. However, there was significantly more new bone in the experimental group according to histological and radiographic examinations. At d10 and d20, alkaline phosphatase activity of the local tissue in the experimental group was significantly greater than that in the control group, and calcium and phosphonium contents of samples were also greater in the experimental group. Arrangement of collagen fibers became more regular in the experimental group than that in the control group. Conclusion NGF possesses synergistic effect on ectopic bone formation induced by rhBMP-2.
ABSTRACT
The ectopic bone formation is a condition in which mature lamellar bone is formed in tissues that do not normally ossify, which was first described by Riedel in 1883. It has been observed at sites of chronic infection, hemorrhage, fibrous scarring or contracture. The pathophysiology of ectopic bone formation is not clearly identified but has complex and multifaceted causes, which resulted to differentiate the non-circulating pluripotent mesenchymal cells to osteoblastic stem cells. The local environment conditions of trauma, disruption of soft tissues and periostium, bone debris, hematoma, damaged muscle, uncommitted fibroblasts are suspected to be one of the causes of this condition. Comparing to simple soft tissue calcification, the ectopic bone has all the morphologic and biochemical characteristics of orthotopic bone, which is subjected to turnover and even has the ability for bone marrow formation. A case of late occlusion in a femoro-post. tibial PTFE graft about 5 months after vascular reconstruction due to ectotopic bone formation, which is confirmed by pathology around the graft is presented. After excision of the ectopic bone around the inflow vascular anastomosis site with re-vascularization, the patient was free from the ischemic leg symptoms. We reported a case of occlusion of vascular anastomosis site by ectopic bone formation with review of literature.