Effect Of BMP-2 Gene Mediated By Adeno-associated Virus On The Rabbit Anular Needle Puncture Model Of Intervertebral Disc Degeneration.

Objective:To evaluate the potential of bone morphogenetic protein 2 (BMP-2) gene therapy application on rabbit interverbral disc degeneration, using the recombinant Adeno-associated virus vector expressing BMP-2.Methods:1. L2-3,L3-4,L4-5,L5-6 lumbar discs of 48 skeletally mature New Zealand white rabbits were punctured to set up interverbral disc degeneration model.2. Subsequently, 48 rabbits were randomly divided into three groups. Group A (n = 16) were injected with the Adeno-associated virus expressing BMP-2, Group B (n = 16) were injected with Adeno-associated virus only while Group C (n = 16) were injected with saline .3. Four rabbits were randomly selected from each group after injection 2 weeks,4 weeks and 8 weeks. The rabbits were killed after lumbar MRI scanning and L2-3,L3-4,L4-5,L5-6 lumbar discs of each rabbit was collected. Spectrophotometry were performed to determine proteoglycan synthesis.4. To kill the left X rabbits after 8 weeks of the injection,attaining material to make up pathology slice and the expression of collagen type II and collagen type I were be analysis in order to observe the situation which AAV-BMP-2 makes effect on reserving the degeneration of the intervertebral disc.Results:1. In Group A, there were no significant difference in magnetic resonance imaging (MRI) at all time points (P>0.05) In constrast, in Group B, Group C, there were significant difference in MRI at all time points(P<0.05).The comparison among these three group showed there were significant difference between Group A and Group B (P<0.05) , Group A and Group B (P<0.05), while there were no significant difference between Group B and Group C (P>0.05).2. The proteoglycan quantity in the nucleus pulposus comparison showed there were significant difference between Group A and Group B (P<0.05) ,Group A and Group C (P<0.05), while there was no significant difference between Group B and Group C (P>0.05).3. It can be seen from the microscope that the degree of disc degeneration in A group was slighter than theB and C group, while can not recover normal state.4. The results of immunohistochemical staining showed that there were more strong expression of collagen type II in A group than that of in B and C group. On the contrary ,there were more strong expression of collagen type I in B and C group than that of in A group(P<0.05). It was the same to B and C group ( P<0.05).Conclusion:Our study indicates that BMP-2 gene mediated by adeno-associated virus induced a restoration of intervertebral disc degeneration.