Establishment of rabbit models of ischemic lumbar vertebrae adjacent to endplate: Feasibility of MRI and pathology verification

BACKGROUND: Currently, the widely used intervertebral disc degeneration models are induced by altering intervertebral disc biomechanics, damaging intervertebral disc structure or changing hereditary features with genetic technique. All these methods are varies from natural duration of intervertebral disc degeneration. OBJECTIVE: To evaluate the feasibility of the establishment of rabbit model of ischemic lumbar vertebrae adjacent to endplate by percutaneous puncture followed by pingyangmycin injection. METHODS: A total of 46 New Zealand white rabbits were selected and two vertebraes were divided as experimental group (L₅) and control group (L₄) in every rabbit. Vertebrae adjacent to endplate was punctured. Pingyangmycin (2 g/L) 1 mL was injected into rabbits in the experimental group. And 1 mL normal sodium was injected into the control group. Lumbar artery angiography was performed in 4 rabbits before operation. Six rabbits were randomly performed MRI and then were executed for vertebral histology at weeks 1, 2, 3, 4, 5 and months 2, 3 after operation. Ischemic areas of L₅ were measured by the MRI and histological section at week 4 after operation. RESULTS AND CONCLUSION: MRI and histology of control group had not specific changes. MRI had not significant signal intensity changes in the first 2 weeks in the experimental group. At week 3 after operation, it demonstrated slightly hyperintense signal on T ₂-weighted image (T₂WI) and fat-suppression T ₂-weighted image (FS T₂WI), while fat-suppression T ₁-weighted image (FS T₁WI) was hypointense signal. The signal changed more obviously at week 4. Histology of experimental group had not specific changes in the first 2 weeks. From weeks 3-4, bone trabecula arranged confusedly and disorderly, with gradually decreased osteocyte and marrow haemocytes, while adipocytes increased and coalesced. Cartilage corpuscle of endplate decreased and architecture became disorder. But the anulus fibrosus and nucleus pulposus had no obviously changes. The intervertebral disk of the experimental group degenerated at week 5, and the ischemia of lumbar vertebrae still existed and intervertebral disk degenerated more obviously at months 2-3 after operation. There was significant positive correlation of ischemic areas of experimental group between MRI and histology at week 4 (r=0.965, P < 0.001). The rabbit model of ischemic lumbar vertebrae adjacent to endplate can be established successfully by percutaneous puncture vertebrae adjacent to endplate followed by pingyangmycin injection. The operation is minimally invasive, simple and reproducible, with high success rate. This is a fairly ideal animal model to study the degeneration of the lumbar spine and intervertebral disc.