The Possible Mechanism Of β-NGF Regulating The New Bone Formation

Objective:Osteogenesis in the bone defect has been well studied. Many studies have showed various of biologically active proteins play an important role during process. In order to evaluate the effect of β‐NGF on bone formation and bone remodeling, standard rat skull critical bone defects were made and early locally continuous infusion of β‐NGF model were established. In addition, expression of BMP‐2and osteoclast activity were measured to study the possible mechanism during the new bone formation in bone defect regulated by β‐NGF.Methods:Two5‐mm diameter critical bone defects were symmetrically created on the parietal bone followed by the placement of college I bone substitute into the bone defects. The bone defect on the right side was given by10ug beta‐NGF PBS solution and the left side was given only by PBS solution via osmotic pump over7days after surgery. New bone formation were evaluated using HE staining and Gomori modified trichrome staining. Expression levels of BMP‐2at3、7、14、21and28days time points postsurgery were studied by using immunohistochemical technique and semi‐quantitative analysed by integrated optical density (IOD). Expression levels of tartrate‐resistant alkaline phosphatase (TRAP) at each time point were used to evaluate the osteoclast activity and semi‐quantitative analysed IOD.Results:The animal model of early locally continuous infusion of β‐NGF via osmotic pump followed by making rat skull critical bone defects were established successfully according to the HE and Gomori modified trichrome staining. The study of new bone formation using Gomori modified trichrome staining showed significantly increased after locally β‐NGF application (P <0.05) at the14d,21d and28d. Immunohistochemistry studies showed the expression levels of BMP‐2in the experimental group had significantly higher IOD values (P <0.05) when compared to control group at14d. Special staining TRAP staining results showed that the activities of osteoclasts of experimental group decreased significantly compared to the control group (P <0.05) at7d,21d and28d time points. Conclusion:Locally continued administration of β‐NGF can be successfully established by using osmotic pump. Locally application of β‐NGF during bone healing can promote the new bone formation and bone remodeling. Increased the production of BMP‐2and inhibition of the osteoclast activity may play important roles during osteogenesis regulated by β‐NGF.