| Objective.To establish a animal model of rabbit intervertebral disc degeneration caused by puncturing posterolateral lumbar disc annulus fibrosus and aspirating nucleus pulposus.To observe the influence of rhGDF-5 to disc degeneration induced by aspirating the nucleus pulposus.Methods.①The L3-4 lumbar intervertebral discs of 8 Japanese white rabbits were stabbed by 21-gauge hypodermic needle into a depth of 5 mm in the posterior annulus fibrosus,then some nucleus pulposus tissues were aspirated out.Comparisons of disc height,magnetic resonance imaging,and histologic analyses of the stabbed discs and intact L2-3 disc(as control group) were performed preoperatively at 8 weeks after surgery.②Another 32 Japanese white rabbits were chosen in the experiment after the lumbar discs MRI scan and radiograph.Degeneration model was induced in rabbits by aspirating the nucleus pulposus from L1-L2,L3-L4 IVDs through an posterolateral approach.Each intervertebral disc served a specific role after the nucleus pulposus being aspirated:L1-L2 was given single injection of PBS 20ul,L3-L4 was given single injection of growth and differentiation factor-5 20ul, L2-L3 was the normal control.Comparisons of disc height,magnetic resonance imaging,and histologic grading were made by 2,4,8,12 weeks after treatment.Results.①At 8 weeks after the operation,the disc height become obviously narrow in the model group.The mean disc height index of model group was 64.25±2.78%,compared to 95.26±2.15%of the control group.The mean disc height index of model group was statistically significant at the 4,8 and 12 week time points(P＜0.01).The magnetic resonance imaging signal decilned significantly at 8weeks postoperatively.Histologically,in the model group showed severely degenerated discs in which most of the contents of the nucleus pulposus had been lost,an increase in connective tissue,annulus fibrosus with severely reversed contour were apparented.②At 2 weeks after the operation,the mean disc height index and of the magnetic resonance imaging signal progressive decilned in both PBS and rhGDF-5 group.The mean disc height index and of the magnetic resonance imaging scores with rhGDF-5 injection was statistically significant at the 4,8 and 12 week time points (P＜0.05).Histologically,in the PBS group showed severely degenerated discs in which most of the contents of the nucleus pulposus had been lost,the severely rupture of the annulus fibrosus with reversed contour were apparented.At 12weeks,an increase in connective tissue with the loss of definition between nucleus pulposus and annulus fibrosus in the PBS group were apparented.In the rhGDF-5 group,enlarged,rounded,darkly stained nucleus chondrocyte-like cells were also seen and in clones in nucleus pulposus nucleus pulposus and the inner anulus fibrosus with the moderately serpentine appearance or rupture of the annulus fibrosus at 4 weeks.The chondrocyte-like cells were cloned more significantly at 8 weeks.At 12 weeks,the nucleus pulposus also consisted of chondrocyte-like cells and the hyalinization apparented in the nucleus pulposus and annulus fibrosus with severely reversed contour in the rhGDF-5 group.The histologic grading scores with rhGDF-5 injection was statistically significant at the 4,8 and 12 week time points(P＜0.05).Angiogenesis, osteophyte and cellular infiltration were not seen in the inner or middle layers of the anulus fibrosus or in the nucleus pulposus in any section of any group.Conclusions.(1) Aspirating the nucleus pulposus from discs could induce lumbar intervertebral disc degeneration.(2) A single injection of rhGDF-5 could retard the loss of disc height and warter,presumably based on its effects to stimulate clone of intervertebral disc cells.The results have implications in the early growth factor intervention of disc degeneration to slow the degenerative process.MeSH Terms:Intervertebral Disk/PathologyDisease Models,AnimalBone Morphogenetic proteins/therapeutic useIntervertebral Disk/radiographyMagnetic Resonance Imaging@GDF-5@Aspiration of Nucleus Pulposus@Disk Degeneration... |
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