ABSTRACT
BACKGROUND:Mechanical strain certainly has an effect on physiological activities of osteoblasts. Runx-2 is a target of bone morphogenic protein signal and is an important factor for regulation of osteoblastic differentiation. Bone morphogenic protein signal transduction pathway is involved in physiological response of osteoblast to stimulation of mechanical centrifugal force. OBJECTIVE:To observe the effect of mechanical centrifugal force on bone morphogenetic protein signal pathway under different time period and speed. METHODS:MC3T1-E1 cells were pre-treated in DMEM medium containing 10%fetal bovine serum for 24 hours, and then divided into control group, 90 r/min group, 180 r/min group and 250 r/min group. Each group was then subdivided into 6 hours, 12 hours and 24 hours centrifugation subgroups. Experiments were repeated for three times for different centrifugal speed and different time period. Except centrifugation, the control group was under the same environment. Total RNA was extracted and reversely transcribed into cDNA. Runx-2 gene expression was determined by real time fluorescent quantitative PCR. RESULTS AND CONCLUSION:The expression of Runx-2 mRNA was increased with extension of time, showing a positive correlation between the two. The mRNA expression at 180 r/min was significantly higher than that at 90 r/min and 250 r/min (P<0.01);at 90 r/min and 180 r/min, the Runx-2 mRNA expression was higher than that in the control group (P=0.039), both of them showed significant difference along with the time. The difference of centrifugal force speed and duration is associated with different physiological response of osteoblasts in bone morphogenic protein signal pathway, which plays an important role in mechanical signal transmission and cascade reaction.
ABSTRACT
Objective To investigate the ability of repairing bone defect with the compound of hydroxyapatite(HA),red bone morrow (RBM), bone morphogenic protein(BMP)and fibrin sealant (FS),and the feasibility with the compounds as bone substitute material. Methods The animal models of bilateral radius bone defect were created by surgery in the New Zealand white rabbits, and were treated with the compound of HA, RBM, BMP and FS, by autograft and no implant as control.The effect were observed by gross, histopathological and X-ray examinations, and were determined by biomechanics at 2,4,8 and 12 weeks after operation. Results By gross, histopathological and X-ray examinations, the effect indicated that the bone defect were perfectly repaired with autograft and the compound of HA, RBM, BMP and FS at 12 weeks, but not with the no implant group. The effect of biomechanics had no statistically significant difference between the autograft and the compound of HA, RBM, BMP and FS. Conclusion The compound of HA, RBM, BMP and FS possesses much high bone inductive potentialities and the ability of rebuilding bone defect and can serve as an autograft substitute material.