[Transfection of lentivirus-bone morphogenetic protein 2 and lentivirus-inhibitor of differentiation 1 into nucleus pulposus for delaying intervertebral disc degeneration in an in vivo rabbit model].

OBJECTIVE: To investigate if the course of intervertebral disc degeneration (IDD) is delayed by injecting lentivirus (Lv) vector carrying bone morphogenetic protein 2 (BMP-2) and inhibitor of differentiation 1 (Id1) genes directly into the nucleus pulposus. METHODS: Thirty-two New Zealand white rabbits, 2.0-2.5 kg in weight and 4 months in age, were used to establish the IDD models at L (3, 4), L (4, 5), and L (5, 6) discs with annular puncture via transabdominal approach. Thirty rabbits with successful modeling were randomly divided into 5 groups, 6 rabbits every group. At 4 weeks after modeling, rabbits were injected with Lv-BMP-2 (group A), with Lv-BMP-2 and Lv-Id1 (group B), with Lv-Id1 (group C), with Lv-green fluorescent protein (group D), and with PBS (group E). At 2, 4, and 8 weeks after injection, T2-mapping MRI was performed on 2 rabbits each group to obtain the T2 values, and then subsequently the lumbar disc tissues were harvested to test the mRNA expressions and contents of collagen type II and proteoglycan by real-time fluorescent quantitative PCR and ELISA methods. RESULTS: T2-mapping MRI demonstrated that there was no significant difference in the T2 value between different groups at immediate and 2 weeks after injection ( P>0.05). The T2 value of groups A and B was significantly higher than that of groups C, D, and E at 4 weeks after injection ( P<0.05), but no significant difference was observed between group A and group B ( P>0.05). The T2 value of group B was significantly higher than that of the other groups at 8 weeks after injection ( P<0.05). The real-time fluorescent quantitative PCR and ELISA showed that the expressions and contents of collagen type II and proteoglycan in group B were significantly higher than those in the other groups at 2, 4, and 8 weeks after injection ( P<0.05). CONCLUSION: Combined application of Lv-BMP-2 and Lv-Id1 can delay IDD changes in rabbit IDD models.