ABSTRACT
BACKGROUND: Preliminary experiments show that bone marrow mesenchymal stem cells transfected with SOX9 gene can grow and proliferate in Pluronic F-127 hydrogel, promote the secretion of extracellular matrix, and increase the expression of cartilage matrix. OBJECTIVE: The SOX9 gene was transduced into bone marrow mesenchymal stem cells by lentivirus gene induction, and then combined with injectable Pluronic F-127 hydrogel to observe the effect of Pluronic F-127 hydrogel on repairing cartilage defects. METHODS: SOX9 gene was transfected into bone marrow mesenchymal stem cells by lentivirus gene induction. After 48 hours of transfectlon, SOX9 gene was combined with Pluronic F-127 hydrogel. Sixty New Zealand white rabbits provided by the Experimental Animal Center of Wuhan University of Science and Technology were selected to establish the models of femoral condylar cartilage defect of the right knee joint. The rabbits were randomly divided into three groups: model group without implantation of any material at the defect site, control group with implantation of non-transfected bone marrow mesenchymal stem cells and Pluronic F-127 hydrogel complex at the defect site, and experimental group with implantation of SOX9 gene-transfected bone marrow mesenchymal stem cells and Pluronic F-127 hydrogel complex at the defect site. Four and twelve weeks after operation, the defect tissues were taken for three-dimensional reconstruction of micro-CT, hematoxylin-eosin staining, Safranine O staining, type II collagen immunohistochemical staining and Wakitani soft tissue repair histological score. This study was approved by the Ethics Committee of Wuhan University of Science and Technology. RESULTS AND CONCLUSION: (1) At 12 weeks after operation, three-dimensional reconstruction of Micro-CT showed that there was no obvious repair In the defect area of the model group, and there was still a large depression In the center. In the control group, the central depression area was significantly reduced and more trabecular structures of regenerated bone were observed. In the experimental group, the defect area was basically repaired. (2) At 12 weeks after operation, hematoxylin-eosin staining showed that there was no trabecular bone structure, disordered cell distribution and no cartilage lacunae at the defect area of the model group. In the control group, more bone tissue was reconstructed, and the defect area was mainly filled with cartilage-like tissue and fibrous tissue. In the experimental group, bone tissue was reconstructed adequately, and the defect area was mainly filled with chondroid cells and chondroid extracellular matrix. Cells arranged columnariy, similar to the surrounding cartilage. (3) At 12 weeks after surgery, Safranine O staining and collagen II immunohistochemical staining results showed that a small amount of glycosamlnoglycan was observed, but no type II collagen was found in the model group. The expression of glycosaminoglycan and type II collagen was more in the control group. The expression of glycosaminoglycan and type II collagen was highest In the experimental group compared with the other two groups. (4) The histological score of Wakitani soft tissue repair in the experimental group was higher than that in the control group and model group (P < 0.05). (5) The results suggested that Pluronic F-127 hydrogel complex loaded with SOX9 gene transfected bone marrow mesenchymal stem cells can promote the repair of cartilage defects.