BACKGROUND:Transplantation of mesenchymal stem cels to prevent and treat degeneration of the intervertebral disc is a feasible method. Mesenchymal stem cels co-transfected by SRY-related high mobility group-box gene 9 (SOX-9) and growth differentiation factor-5 (GDF-5) can differentiate into nucleus pulposus cels, in order to obtain greater effect of induction and proliferation of nucleus pulposus cels. OBJECTIVE:To investigate the effect of SOX-9 and GDF-5 co-transfection on the differentiation of rabbit bone marrow mesenchymal stem cels into nucleus pulposus cels. METHODS: We separated and cultured bone marrow mesenchymal stem cels from the bone marrow of rabbit aged 4 months. Passage 3 cels were divided into five groups andin vitro induced to differentiate into nucleus pulposus cels: non-transfected group, empty vector transfection group, SOX-9 transfection group, GDF-5 transfection group, SOX-9 and GDF-5 co-transfection group. At 14 days after transfection, RT-PCR was employed to assay SOX-9, GDF-5 and colagen type II mRNA expressions in bone marrow mesenchymal stem cels. The marker of nucleus pulposus cels-KRT19 expression was also detected by immunohistochemical staining. RESULTS AND CONCLUSION:In the co-transfection group, the mRNA expressions of SOX-9, GDF-5, and colagen type II were significantly higher than those in the SOX-9 transfection group, GDF-5 transfection group, and both these two groups, respectively (P < 0.05). Cels were positive for KRT19 in the SOX-9 and GDF-5 groups, and strongly positive for KRT19 in the co-transfection group. These findings indicate that double gene-transfected bone marrow mesenchymal stem cels are better than single gene-transfected cels with regard to differentiation into nucleus pulposus cels and secretion of extracelular matrix.

Objective To explore the function and clinical effect of automatic nerve retractor in micro-endoscopic discectomy.Methods From August 2009 to December 2010,350 patients with lumbar disc hemiation were treated by micro-endoscopic discectomy,including 196 males and 154 females,aged from 17 to 68 years (average,42 years).Three cases were at L1-2,8 at L2-3,12 at L3-4,186 at L4-5 and 141 at L5S1.The automatic nerve retractor was used in all micro-endoscopic discectomy.The visual analogue scale (VAS) and Oswestry disability index (ODI) were used to evaluate clinical outcomes.Results All patients were followed up for 6 to 16 months (average,9 months).The mean VAS score decreased from preoperative 8.79±1.15 to 3.80±1.14 3 months after operation and 3.65±1.14 6 months after operation.The mean ODI score decreased from preoperative 78％±1.71％ to 28％±1.72％ 3 months after operation and 28％±1.88％ 6 months after operation.Postoperative VAS and ODI scores decreased significantly compared with those before operation.The VAS and ODI scores 6 months after operation were not significantly improved compared with those 3 months after operation.No spinal cord and nerve root injury and epidural hematoma formation occurred in all cases.Conclusion In micro-endoscopic discectomy,the automatic nerve retractor can help the operator obtain effective exposure,protect nerves from injury,alleviate workload of the operators,therefore it has a great clinical application value.