Compression suture: A method for simulating intervertebral disc degeneration in rats induced by excessive loading

BACKGROUND: Research has demonstrated that excessive loading can induce intervertebral disc degeneration (IDD). However, existing animal models have inherent limitations, and there is still no reliable model to investigate the effects of excessive loading on IDD. This study aims to develop an in vitro model of simulated excessive loading. METHODS: A total of 24 twelve-week-old Sprague-Dawley rats with similar body weights were randomly divided into four groups. In the compression suture group, a 5-mm-wide tail skin was removed, and the defect was compressed sutured with 2-0 silk thread. In the sham surgery group, only a 5-mm-wide tail skin was removed without compression suturing. All animals underwent radiological, histological, and molecular analysis at 2, 6, and 10 weeks postoperatively. RESULTS: X-rays and magnetic resonance imaging showed that the height of the intervertebral disc (IVD) and the water content of the nucleus pulposus (NP) decreased in the compression suture group. The histological results showed that the tissue structure of IVDs was disordered, and the proteoglycan content was reduced in the compression group. Compression induced upregulation of MMP-3 and MMP-13 expression in NP cells, whereas the expression of collagen II and aggrecan was downregulated. Additionally, an increased inflammatory response and apoptosis level were detected in NP cells of the compression group. CONCLUSION: We conclude that simulated excessive loading induces IDD in rats. This is a reliable and highly reproducible IDD model that will provide a foundation to investigate the effects of excessive loading on IDD.