Repair Of Rabbit Growth Plate Defects With Tissue-engineering Cartilage: Compound Of Autologous Bone Marrow Mesenchymal Stem Cells And Biological Scaffold

BackgroundEpiphyseal plate injury may cause severe growth arrest because it result in the bony bridge between the epiphysis and metaphysis,earlier closure of epiphyseal plate and limb length discrepancy and angular deformity, Traditional treatments for bony bridge include resecting the bone bar and setting an interpositional material such as fat and bone cement,and they are only efficient for less then 30% growth plate defects.Recently,Tissue engineering technique have provided many new alternatives for treatment of growth plate injury.This experiment rabbit marrow-derived mesenchymal stem cells were isolated and cultured in vitro, Then induced to differentiate into chondrocytes under three-dimension condition and serum-free medium;and transplate the cultured cartilage into growth plate defects.lt may provide the appropriate cartilage necessary to restore growth potential and prevent transphyseal bone bridge formating. It is a promising way for clinic treatment of growth plate defects. Objectives1 .To explore the behavior of MSCs which were isolated from rabbit bone marrow in vitro and investigate the feasibility of MSCs as seed cells of tissue engineering.2.To study the feasibility and application value of MSCs being seed cells of tissue engineering,which were induced to differentiate into chondrocyte.3.To construct tissue-engineering cartilage ,MSCS were seeded on the biological scaffold-poly-DL-lactic acid and cultured under three-dimension condition.4. To investigate the feasibility of repair the growth plate defects with the compound of tissue engineering cartilage. Methods1. MSCs were extracted from rabbit bone marrow and purified, then proliferated in vitro.They were observed under phase-contrast microscope and the growth curve was drawn accordingly.2. MSCs were induced to differentiate into chondrocytes first under serum-free medium contain TGF-pi and dexamethsone in monolayer culture,then under three-dimension condition with PDLLA and IGF-1 .3. The compound were implanted into the growth plate defects of proximal tibial of 8-weeks rabbits.After 4 tlu 8th and 16 th weeks, gross observation, X-ray, histologic examination were performed to evaluate the efficiency.Results1. MSCs which were in low abundance proliferated when cultured in vitro and cell survival rate were 90 % ~95 %.2. After being induced to differentiate into chondrocyte, there are much toluidine blue metachromasia matrix around the cell by toluidine blue staining.3.The rabbits tibia had no marked deformities after 4 weeks of operation, histologic examination revealed that the defects were filled with cartilage; After 16 weeks, the experiment group had deformities , histologic examination showed nearly closure of growth plates. On the contrary, the control side formed severe deformities and growth plate were closed. Conclusionl.The success of culture MSCs in vitro will be useful for repairment of cartilage , skeletal tissue defects by tissue engineering technique in the future.2. MSCs can be induced to differentiate into chondrocytes under three-dimension condition and serum-free medium .3. PDLLA was a sponge-like porous structure and MSCs showed high level of proliferation. PDLLA was a good carrier for cartilage tissue engineering.4. Transplation of cultured cartilage into growth plate defects may replace growth plate tissues, maintain normal growth of limbs and prevent developmental deformity, And it is a promising way for clinic treatment of growth plate defects.