| Background Low back pain continues to be a major cause of morbidity. The disc undergoes characteristic biochemical, structural, and morphologic changes while degeneration, which result in many clinical sequel associated with low back pain. The most dramatic effects are in the nucleus pulposus. Profound effects on ceil viability and matrix composition have been seen. As a result, many believe that disc degeneration is initiated in the nucleus pulposus. Several of the initial investigations directed towards therapeutic intervention of the inlervertebnal disc degeneration involved Ihe use of growth factors. However, it has become increasingly evident that a major shortcoming of growth factor usage is its short-lived duration of effectiveness. Gene therapy is a novel approach thai overcomes ihe short- term expression problems associated with exogenous growth factor administration, while maintaining many of the growth factor's potentially beneficial effects. The initial studies aimed at gene transfer to the intervertebral disc were feasibility studies. Nishida et at. reported adenovinis-mediated transfer of the LacZ marker gene to the rabbit intervertebral disc cells. In vivo Marker gene expression continued at qualitatively undiminished levels for at least 12 weeks. They performed an in vivo study to determine the feasibility of adcnovirus-mcdiatcd therapeutic gene transfer to the intervertebral disc and the result showed that the discs of the therapeutic gene group exhibited a statistically significant increase in proteoglycan synthesis compared to the control discs, which suggests that gene therapy may have applications in treating disc degeneration with regard to matrix regeneration. However, these above research results were acquired from ihe discs with normal physiological function in heaithy body, but not the disc degenerated The later possesses a less amount of cells with more inactive function. Jt is still unknown whether the adenoviral vector system be a suitable delivery mechanism for transferring therapeutic genes to the cells in degenerated intervertebral disc, and whether the therapeutic gene can be successfully expressed for a long term. If the expression of the therapeutic gene and the production of proteoglycansynthesis indeed increased significantly in the degenerated disc, gene therapy has the possibility to become an effective early-stage treatment strategy for disc degeneration disease.Objective To explore the exact time point for intervention of disc degeneration induced in the rabbit model by injuring the intervertebral stability of the lumbar spine, n To study the biological characteristics of the cells harvested from nucleus pulposus, annulus fibrosus, and meniscus. The effect of IGF-1 on the proliferaion and protylgrcan synthesis of nucleus pulposus cell was concentrated, u To observe the expression of human IGF-1 gene and the synthesis of proleoglycan in degenerated discs thai had been transferred human IGF-1 gene by adenovirus-X.Methods 27 rabbits were divided into an operating group and a control group. The operating group was incised through posterior approach along spmous process and resected the supraspmai and interspinal ligament and the posterior half of the zygapophysial joint between the third and the sixth lumbar spine. The control group was incised only by the skin. Ail of the rabbits were examined 2,4 and & months later with roentgenogram, MR1, dual energy radiograph absorptiometry and histology. The cells of nucleus pulposus, annular fibrosus and meniscus were harvested from two-month-old rabbits and cultured in DMEM/F12 contain 10% FBS to observe the growth characteristics in plain cutturing system. The original nucleus pulposus cell was incubated with different concentration of IGF-1 (0.1 ng/ ml, 1.0 ng/ ml, 10 ng/ ml). The proliferation and proteoglyean synthesis of these cells was examined with MTT and 35S incorporation rate. The second passage of nucleus pulposus cell was implanted at the surface of decalcified bone matrix for 48h and observed by SEM. D T...
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