Laser-treated Nucleus pulposus as an innovative model of intervertebral disc degeneration

This study describes an innovative experimentally induced model of intervertebral disc degeneration. This innovative approach is based on the induction of extracellular matrix disorders in the intervertebral disc (IVD) using a diode laser. For this study, 15 one-year-old and five 30-month-old New Zealand White rabbits were used. Two procedures were tested to trigger IVD degeneration: needle aspiration (reference technique) and a laser approach. The IVD degeneration process was assessed 20, 40, 60, 90 and 120 days after surgery by X-ray radiography (IVD height), magnetic resonance imaging (MRI) (T2 intensity of IVD signal) and histological analysis using modified Boos' scoring. Our data indicate that a marked IVD degeneration was found compared with sham-operated animals regardless of the procedure tested. A significant decrease in disc height on X-ray radiographs was first demonstrated. In addition, MRI disc signals were significantly reduced in both groups. Finally, a statistically significant increase in Boos' scoring was found in both laser and aspiration-induced IVD degeneration. Interestingly, IVD degeneration induced by laser treatment was more progressive compared with aspiration. Moreover, the histological results indicated that laser-induced disc degeneration was quite similar to that obtained during the natural aging process as observed in 30-month-old rabbits. Our study describes the consistency of this innovative experimentally-induced animal model of IVD degeneration. The radiological, MRI and histological data confirm its relevance. The histological examination indicates that IVD degeneration induced by laser treatment is comparable to the degenerative process observed during the onset of spontaneous IVD degeneration. This model could be a useful tool to help us validate biomaterial-assisted, cell-based, regenerative medicine strategies for the prevention and treatment of IVD degeneration.