ABSTRACT
BACKGROUND: Concentrated growth factor (CGF) fibrin membrane is involved in metabolism regulation, which has been applied in bone remodeling. Previous Studies have found that the cytoplasts of osteoblasts, interstitial cells and osteocytes in distraction osteogenesis are positive for osteoprotegerin and receptor activator nuclear factor kappa B ligand (RANKL).OBJECTIVE: To explore the mechanism of bone orthopedic effect and the promotion effect of CGF fibrin membrane on the distraction osteogenesis of the rabbit mandible.METHODS: Twenty-four white rabbits were randomly selected. Distraction osteogenesis was performed unilaterally in the rabbit left mandible (control group); CGF fibrin membrane was fixed on the inner surface of distractor, and the distraction gap was then completely wrapped prior to distraction osteogenesis in the right mandible (experimental group).At 1, 7, 14 and 28 days of consolidation period, the rabbits were sacrificed and the bilateral mandibles were taken for hematoxylin-eosin staining, western blot assay and immunohistochemical staining to detect the expression of RANKL and osteoprotegerin in the newborn bones; the osteogenesis in the distraction gap was observed and compared between two groups.RESULTS AND CONCLUSION: The osteoprotegerin positive cells and positive area percentage in the experimental group were significantly higher than those in the control group at 1, 7 and 14 days after distraction osteogenesis (P < 0.01). The RANKL positive rate and positive area percentage in the experimental group were significantly higher than those in the control group at 1 and 14 days after distraction osteogenesis (P < 0.05 or P < 0.01). Western blot assay showed a higher ratio of RANKL/osteoprotegerin in the control group than the experimental group (P < 0.01). Our findings indicate that CGF fibrin membrane can promote osteogenesis and mineralization in the distraction gap of the rabbit mandible, which is beneficial for distraction osteogenesis in the mandible.
ABSTRACT
BACKGROUND:Integfin levels can affect cellular function,regulate bone formation and bone resorption.However,this process need activated by other factors,whether recombinant human bone morphogenetic protein 2 (rhBMP-2)has this effect is poorly understood.OBJECTIVE:To study the effects of the different concentration of rhBMP-2 on the expression of inergrin β_1 during the mandibular dfScraction in rabbits.DESIGN,TIME AND SETTING:The randomized,controlled.animal grouping experiment of histological observation was performed at the Animal ExperimentaI Center and Immunohistochemistry Center of Liaoning Medical University from May 2006 to May 2007.MATERIALS:A total of 45 Japanese white rabbits were used.rhBMP-2 was supplied by Beijing Academy of Military Medical Sciences.METHODS:The rabbits were prepared for mandibular distraction models and randomly assigned into control,1.5 mg rhBMP-2 and 3.0 mg rhBMP-2 groups.with 15 animals in each group.Collagen sponge and collagen binding proteins were implanted into mandibles of rabbits,respectively,and distraction 0.4 mm per time,twice per day for 5 days.The mandibles were lengthened 4 mm.MAIN OUTCOME MEASURES:The expression of integrin 131 was detected using immunohistochemistry at days 1,3,7,14,and 28 after distraction.RESULTS:All rabbits were included in the final analysis.The integdn β_1 mainly expressed at 7 days after distraction.At the same time point.when concenrtation rhBMP-2 was increased,the positive integrin β_1 rate and positive stained area percentage were increased(P<0.05).Compared to the same concentration,the positive integrin β_1 rate and positive stained area percentage were gradually increased as time prolonged (P<0.05).CONCLUSION:The integdn β_1 expression can be promoted by rhBMP-2 at the anaphase of mandibular distraction osteogenesis in a concentration-dependent manner.