ABSTRACT
<p><b>OBJECTIVE</b>To study the overexpression of Sox9 gene on rabbit bone marrow mesenchymal stem cells for repairing articular cartilage injury in vivo.</p><p><b>METHODS</b>Rabbit bone marrow mesenchymal stem cells (BMSCs) were transduced with lentivirus vector containing Sox9 gene and then cartilage specific molecule was detected by RT-PCR in vitro. Total 48 knee joints of 24 mature New Zealand white rabbits were randomly divided into 3 groups according to different defect treatment. After animals anesthesia,a full-thickness cylindrical cartilage defect of 4 mm diameter and 3 mm deep was created in the patellar groove using a stainlesssteel punch. Meanwhile, the transfected cells were implanted to repair the rabbit model with full-thickness cartilage defects. Cartilage defects tissue was observed with light microscope, electron microscope, HE and immunohistochemistry staining to assess the repair of defects by the complex at 6 weeks or 12 weeks after the implantation.</p><p><b>RESULTS</b>At 3 days after the transfection, Sox9 gene expression was highest and Sox9 gene expression decreased with the increase of time. At 3 days after the transfection, the expression of collagen type II began and reached the peak at 14 days. It showed that the bone marrow mesenchymal stem cells went into chondrogenic differentiation after transfected by Sox9 gene. Histological observation showed that at 6 weeks after the operation, the defects in the experimental group was filled with hyaline like cartilage tissue, 12 weeks after operation,the defects of cartilage and subchondral bone had satisfactory healing. Both at 6 and 12 weeks postoperatively, the defects were filled with fibrous tissues in control groups. Meanwhile, immunohistochemical staining of sections with type II collagen antibodies showed the proteins in the regenerated tissue stained positive for type II collagen and stronger than the control groups. The histological scoring system indicated that the cartilage repair of experiment groups were better than the two control groups with statistical significances.</p><p><b>CONCLUSION</b>Overexpression of Sox9 gene on rabbit bone marrow mesenchymal stem cells (BMSCs) promote the repair of cartilage defect.</p>