Effect Of Bone Morphogenetic Protein-2(BMP-2)on Intervertebral Disc Degeneration

Objective: The purpose of this study was to probe the role of bone morphogenetic protein-2(BMP-2)in alleviating intervertebral disc degeneration.Methods: The rodent tail model was established,and self-control study was performed according to different time points.Forty Sprague-Dawley(SD)rats were taken,and their caudal C4/C5 segments were used as the control group,C6/C7 segments as the model group,C7/C8 segments as the empty vector group,and C8/C9 segments as the therapy group.The C6/C7,C7/C8 and C8/C9 segments were molded respectively.The C7/C8 segments were injected with empty vector(temperature-sensitive hydrogel PLAPEG-PLA)and the C8/C9 segments were injected with empty vector + BMP-2(temperature-sensitive hydrogel PLA-PEG-PLA solubilized BMP-2 protein)after 6weeks of modeling.Ten rats were examined after 3,6,9 and 12 weeks of modeling,respectively,and the extent of disc degeneration was assessed using MRI to measure DHI(Disc Height Index)and Pfirrmann classification.HE staining(hematoxylin-eosin staining)was used to observe the disc degeneration,and Masuda method was used to score the disc degeneration.The levels of BMP-2 in the nucleus pulposus tissue were detected by immunofluorescence.The expression levels of PCM major protein Perlecan,Laminin,Collagen IV and Nidogen were detected by Western Blot.The expression of integrin α1was detected by immunohistochemistry.Results: 1.MRI results showed that the intervertebral space height became smaller and Pfirrmann classification increased in the model group compared with the control group,and the disc degeneration in the model group gradually increased with time(P <0.05).HE staining results showed that the histological score of the model group showed disc degeneration compared with the control group(P < 0.05).2.After injection BMP-2 into the degenerated discs,MRI and HE staining results showed that the therapy group had obvious therapeutic effects after 9 weeks of modeling.The degree of disc degeneration and intervertebral space height improved with the extension of treatment time.3.The results of immunofluorescence showed that the content of BMP-2 was higher in the control group,and when the intervertebral disc degeneration,the content of BMP-2 decreased,and the results were statistically significant(P < 0.05).4.Western blot results showed that in the process of disc degeneration,the protein expressions of Perlecan,Collagen IV and Nidogen decreased in the model group compared with the control group,while the protein expressions of Laminin increased,with statistical significance(P < 0.05).Western blot results after injection of BMP-2showed that,compared with the model group,the protein expressions of Perlecan,Collagen IV and Nidogen in the therapy group were significantly increased,while the protein expressions of Laminin were significantly decreased,with statistical significance(P < 0.05).5.The results of immunohistochemical showed that the protein expression of Integrin α1 was significantly increased in the model group compared with the control group and was statistically significant(P < 0.05).The protein expression of Integrin α1was significantly decreased in the therapy group compared with the model group,and it was statistically significant(P < 0.05).Conclusion: 1.BMP-2 can delay the intervertebral disc degeneration and has therapeutic effect on the intervertebral disc degeneration in rats.2.The content of BMP-2 in the control group was higher,and the content of BMP-2 decreased during intervertebral disc degeneration,suggesting that BMP-2 may be related to the degree of intervertebral disc degeneration,and it is beneficial to maintain the stability of intervertebral disc.3.The intervertebral disc degeneration was associated with the decreased expressions of Perlecan,Collagen Ⅳ and Nidogen and the increased expressions of Laminin.In the treatment of intervertebral disc degeneration by BMP-2,the expressions of Perlecan,Collagen Ⅳ and Nidogen increased,while the expressions of Laminin decreased,suggesting that the treatment of intervertebral disc degeneration by BMP-2was related to the expression of the main protein of PCM,providing a new idea for the study of the mechanism of BMP-2 treatment of intervertebral disc degeneration.4.Integrin α1 plays an important role in the treatment of intervertebral disc degeneration with BMP-2.