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) MRIin 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 observation6 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) PCRBone 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.