An Experimental Study On Treatment Of Growth Plate Injury In Young Rabbits With Tissue Engineered Cartilage Derived From Native Growth Plate Extracellular Matirx

Growth plate injury in children caused by injures, infection and tumour is the typicaland common disease. Bone bridges caused by growth plate injury may result in lengthdispcrepancy and angular deformity in seriously cases. Nowdays, excising bony bridgeand inserting fat, muscle, bone cement, bone wax as interposition material have beenused to treat the growth plate injury clinically. With the rapid progress oftissue-engineering technology, tissue-engineered cartilages have been used in thetreatment of growth plate injury with success experimental results. Tissue-engineerredcartilage includes seeds cells, scaffolds and cytokine. Scaffold provides growthmicroenvironment for seeds cells in tissue-engineered cartilate, with profit for seedscells adhesion, proliferation and secretion of extracellular matrix. The suitabletissue-engineered cartilage scaffold should possess the source of tissue and columnararrangement of tissue struction which is similar with native growth plate cartilage. Inour study, we produce the tissue-engineered scaffolds with clomular structure derivednavtive growth plate extracellular matrix, and transplant tissue-engineered cartilage withscaffolds and BMSCs into growth plate defect of promixal of tibla in young rabbits inorder to reduce the limb deformity and repait the growth plate injury.Objective: Segragate and extract native extracellular matrix in fetal cattle, producetissue-engineered scaffold with biochemistry composition and structure feature insimilar with the native cartilage, and examine the physic-chemistry character andbiocompatibility. Investigage the effect of tissue-engineered cartilage with scaffolds andBMSCs in the treatment of growth plate defect in young rabbit in order to examine if itcould prevent the formation of bone bridges and reduce the malformation of lowerlimbs in order to repair the growth plate injury.Methods:(1) Growth plate cartilages in the proximal of tibla and distal of femur in fetal cattle were physically shattered into microfilament with the method of pulverizationtechnology. Extracellular matrix fiber suspension was obtained with removal offragment of growth plate cartilage by the methods of different centrifuge and organicsolvent. Columar arrangement scaffolds derived from growth plate chondrocytesextracellular matrix which is similar with native cartilage were produced by theapproach of oriental crystal, freezing drying and physic-chemistry crosslinking. Weanalyzed the tissue structure and physic-chemistry character.(2) BMSCs of youngrabbit were gained by the method of lymphycyte segregation liquid. BMSCs werecultured into scaffolds in order to investigate the proliferation condition of cells and thedegradation and biological compatibility of scaffolds in vivo and vitro.(3) The model ofgrowh plate defect was produced in the proximal of tibia in New Zealand white6-week-rabbits. The rabbits were divided into three groups randomly. Tissue-engineeredcartilage with scaffold and BSMCs and scaffold were transplated into the defect ofgrowth plate. The group of rabbits was not transplanted anything in control group. Theradiographs of both lower legs were examined in order to analyze the lengthdiscrepancy and angular deformity. The specimen were obtained and stained toinvestigate the effect of repairmen of growth plate injury at4-,8-and16-week afteroperation.Results:(1) The chondrocytes extracellular matrix included extracellular matrixcomponent, such as glycosaminoglycan and collegan Ⅱ.The tissue-engineered scaffoldproduced by oriental crystal, freezing drying and physic-chemistry crosslinkingpresented porosity columlar arrangement of tissue structure with proper aperture,porosity and water absorption, which meet the need of tissue-engineered cartilage.(2)BMSCs uniformly distributed in the columlar arrangement of scaffolds, proliferated andsecreted extracellular matrix, which showed that the scaffolds derived extracelluarmatrix had sutible biocompatibility.The biological imitative scaffolds had suitable degradation, biological safety andbiocompatibility without toxicity in vivo. The biological characteristic was significantin construct the tissue-engineered growth plate cartilage.(3) The columnar arrangement of chondrocytes and the chondrocytes lacune were visible in the growth plate defect oftissue-engineerted cartialge group. The light angular deformity and length discrepancywere show up in the radiograph in the tissue-engineered cartialge group, which is lessthan in the other groups after surgery (P<0.01). In scaffold gronps, bone trabecula andresidual scaffold were found in the marginal area without significant inflammationreaction. In the Defect group, the residual space had filled with connective tissue andblood vessels,the cavity had completely collapsed and filled with the bone bridge.Conclusion: We found that transplantation of tissue-engineered cartilage with BMSCsand orientation scaffolds derived from native growth plate extracellular matrix intodefect of growth plate have promoted neogenerative chondrocytes with biologicalfunction of gradually maturation and dedifferentiation and enhancement of limb growthand reduced the angular deformity and length discrepancy of the legs to delay theclosure of injured growth plate and repair the growth palte injury.