Abstract
OBJECTIVES: Intervertebral disc (IVD) degenerates progressively with age and after injuries. In this study, we aimed to characterize early molecular events underlying disc degeneration using a mouse tail IVD injury model. DESIGN: We have established a transcutaneous minimally invasive approach to induce mouse tail IVD injury under fluoroscopic guidance. Morphological and molecular changes in the injured IVDs are compared with the baseline features of adjacent intact levels. RESULTS: After needle puncture, tail IVDs exhibited time-dependent histological changes. The aggrecan neoepitope VDIPEN was evident from 2 days to 4 wks after injury. A disintegrin and metalloproteinase domain-containing protein 8 (adam8) is a surface protease known to cleave fibronectin in the IVD. Gene expression of adam8 was elevated at all time points after injury, whereas the increase of C-X-C motif chemokine ligand (cxcl)-1 gene expression was statistically significant at 2 days and 2 wks after injury. Type 1 collagen gene expression decreased initially at day 2 but increased at 2 wks after injury, whereas no significant change in type 2 collagen gene expression was observed. The extracellular matrix gene expression pattern is consistent with fibrocartilage formation after injury. CONCLUSIONS: Mouse tail IVDs degenerate after needle puncture, as demonstrated by histological changes and aggrecan degradation. The minimally invasive tail IVD injury model should prove useful to investigators studying mechanisms of IVD degeneration and repair.