Experimental animal models of intervertebral fusion-induced adjacent segment degeneration / 中国组织工程研究

ABSTRACT

BACKGROUND:Upright rat intervertebral disc degeneration model can prove that intervertebral fusion can aggravate the adjacent-segment intervertebral disc degeneration, but cannot affirm that spinal non-fusion technology has more advantages. OBJECTIVE:Base on the affirmed intervertebral disc degeneration models of Beagle dog, we performed intervertebral fusion to affirm whether or not the intervertebral fusion can aggravate the adjacent-segment intervertebral disc degeneration. METHODS:Twelve Beagle dogs were randomly divided into two groups. The control group animals were stabbed percutaneous to injure L5/6 disc. The experimental group animals were stabbed percutaneous to injur L5/6 disc. One month later, we made L4/5 intervertebral fusion. At 3 and 6 months postoperatively, lumbar MRI was conducted. L5/6 discs were harvested and subjected to histological observation and PCR. RESULTS AND CONCLUSION:(1) MRI:in the experimental group, 3 and 6 months after fusion, different degrees of intervertebral disk herniation appeared. In the control group, no obvious intervertebral disk herniation appeared. (2) Histological observation:6 months after fusion, in the experimental group, intervertebral disc annulus and nucleus pulposus were disordered;there was a gap in the fold, and the number of nucleus pulposus cel s decreased. In the control group, nucleus pulposus and anulus fibrosus boundary was clear;col agen was loose and arranged regularly. Cel number was more. Anulus fibrosus was close to normal. Col agen fibers were regular and dense. In the experimental group, 3 and 6 months after fusion, type II col agen-positive cel s were less than the control group (P<0.05). Moreover, type II col agen-positive cel s were less at 6 months than at 3 months in the experimental group (P<0.05). (3) PCR:Bone morphogenetic protein 15 and tissue inhibitor of matrix metal oproteinase 1 gene expression was higher in the experimental group than in the control group at 3 and 6 months after fusion (P<0.05). Bone morphogenetic protein 15 and tissue inhibitor of matrix metal oproteinase 1 gene expression was higher in the experimental group at 6 months than that at 3 months (P<0.05). (4) These results suggest that intervertebral fusion can aggravate the adjacent-segment intervertebral disc degeneration.