Effects Of Intraarticular Injection CGRP On The Expression Of Type-â…¡ Collagen And VEGF In The White Area Of The Injury Meniscus Of Rabbits

Objective：The purpose of this study was to observe the exogenous Calcitonin gene-relatedpeptide(CGRP) on the expression of type-II collagen protein and VEGF in the injury tissuesby establishing meniscus injury model of rabbits in the white area, and explore its effects inthe healing process of meniscus injury in the white area, then provide more experimentalevidence for healing of meniscus injury.Methods：Forty-five adult white rabbits of New Zealand were randomly divided into three groupsof A、B、C, each group of15. First,make longitudinal full-thickness laceration on allexperimental animals by using dagger-chips, which was about0.4cm in length and0.1cm inwidth at the junction of the body and anterior horn of the meniscus. Then, suture the incisionlayer by layer.The rabbits in group A were given intraarticular injection with CGRP at dosageof0.5ml every3days untill they were killed. The rabbits in group B were given Fibrin glue0.5ml in the same way untill they were killed.The rabbits in group C were given NS0.5ml inthe same way untill they were killed. The injuried limbs of all rabbits were fixed by self-madesmall splint for1week.Five rabbits of each group were randomly killed at4、8and12weeksafter operation and the experimental menisci were taken out. Then,the gross morphologicalobservation and the pathomorphological observation were performed. The expression of typeII collagen and VEGF were detected by immunohistochemical staining.Results：1.The general observations: with the extension of the observation time, the meniscusfractures in the group A healed gradually and closely bonded. In the group B, granulationtissue hyperplasia was seen in the meniscus split, and the surface of callus was coarse,showing a scar-like repair.In the group C, there was no healing in the meniscus by general observations, and the meniscus split widened over time. The surface of the meniscus becamecoarse, its elasticity decreased,and its texture became soft. Finally, the meniscus appeared todegenerate significantly.2. The histological results: In the group A, the collagen fibers were formed at the4thweek, small amounts of chondrocyte were seen at8th week, collagen fibers tissues andfibrochondrocytes filled in the whole gap at12th weeks, but the collagen arranged inirregular and has differences with normal meniscus. In the group B, the meniscus splitnarrowed at the4th week after operation and granulation tissue formation was visible. At the8th week,collagen increased in the meniscus split, there was no cartilage cells. At the12thweek, collagen fibers and meniscus in the normal tissue combined with each other, showinga scar-like healing. In the group C, all meniscus healing were not seen at4th,8th and12thweek,the chondrocyte gradually decreased in the edge of split and the matrix was in a stateof disorder.3. Immunohistochemical results:In the group A and B, grey value of type II collagenimage was low and no significant change with the passage of experimental period, showingthat type-II collagen expressed highly. In the group C, grey value of type II collagen imagewas high and had an ascending trend, suggesting the expression of type II collagen was notobvious.There were statistically differences (P <0.05) between grey values of type IIcollagen image in the different groups of the same time. Between group A and B, group Aand group C, group B and C,the difference was significant (P <0.05). In the group A, theaverage optical density (OD) values of VEGF image was high and had an ascending trend asthe time going, arriving the peak at the8th week. The OD values of VEGF image began tofall at the12th week. In the group B and C, the OD values of VEGF image was low and hadan descending trend over time. The OD value in the group A was significantly higher thanthat in the group B and C (P <0.05). The differences of OD value between the group B andC were not obvious and there was no statistical significance (P>0.05).Conclusion：1. CGRP can increase the content of type-II collagen and induce synthesis of vascularendothelial growth factor in the healing process of rabbits meniscus injury in the white area,promoting meniscus injury healing in the white area. 2.The effect of CGRP is superior to FG on the rabbit meniscus injury repair in the whitearea.