Treatment of rabbit intervertebral disc degeneration with co-transfection by adeno-associated virus-mediated SOX9 and osteogenic protein-1 double genes in vivo.

Degeneration of the lumbar intervertebral disc is a common cause of low back pain and leg pain that affects the physical and mental health of the patient and increases the social burden. This study was performed to observe the biological effects of adeno-associated virus (AAV)-mediated osteogenic protein-1 (OP1) and SOX9 double gene co-transfection in rabbit intervertebral disc degeneration in vivo. The animals were randomly grouped into models of disc degeneration. After injecting 20 µl of double-gene mixed solution, OP1, SOX9, enhanced green fluorescent protein (EGFP) and PBS buffer into the disc of each group, X-ray analysis, magnetic resonance imaging (MRI), reverse transcription PCR (RT-PCR) and western blotting were performed on the 3rd, 6th and 9th week of surgery. On the 3rd, 6th and 9th week of the transfection, X-ray and MRI showed that the intervertebral height and T2-weighted signal intensity were restored significantly in groups A, B and C, whereas significant differences in intervertebral space and T2-weighted signal intensity were observed between group A and groups B and C (P<0.05). RT-PCR and western blotting showed that the expression of type II collagen and proteoglycan mRNA was upregulated in groups A, B and C. The expression in group A was significantly higher than that in the other groups (P<0.05). Recombinant AAV-mediated SOX9 and OP1 double-gene transfection significantly ameliorated the height of the degenerative intervertebral disc and significantly promoted the high expression of degenerative disc proteoglycan and type II collagen. It can therefore be concluded that dual-gene therapy has a synergistic effect.