Lovastatin prevents discography-associated degeneration and maintains the functional morphology of intervertebral discs

Background context Discography is an important diagnostic approach to identify the painful discs. However, the benefit of discography, a procedure involving needle puncture and injection of the diagnostic agent into the intervertebral disc, is controversial and has been reported to be associated with accelerated degeneration.

Purpose To investigate the effect of lovastatin on the prevention of degeneration caused by a discography simulation procedure in rat caudal discs.

Study design In vivo study using rat caudal discs.

Methods A single flexible 27-gauge needle puncture into rat caudal discs was performed under fluoroscopic monitoring. Different concentrations (0.1, 1, 5, and 10 μM) of lovastatin were prepared and injected into randomly chosen caudal discs. RNA expression of selected genes, histologic, and immunohistochemical staining were performed to evaluate the phenotypic effects of lovastatin on rat caudal discs.

Results Simulation of the discography procedure by puncturing the rat caudal discs with a 27-gauge needle and injection of saline solution induced degenerative changes in the nucleus pulposus with minimal damage to the annulus fibrosus. Aggrecan, Type II collagen, and SOX9 expressions were upregulated, whereas Type I collagen expression was significantly suppressed in discs treated with 5 and 10 μM lovastatin. Discs treated with 5 and 10 μM lovastatin were subjected to alcian blue staining and immunohistochemistry that revealed higher levels of glycosaminoglycans and an increase in the number of cells producing S-100 proteins, Type II collagen, and bone morphogenetic protein-2 (BMP-2), respectively. The most effective phenotypic repair was observed in discs treated with 10 μM lovastatin.

Conclusions Intradiscal administration of lovastatin solution upregulated the expressions of BMP-2 and SOX9 and promoted chondrogenesis of rat caudal discs after needle puncture and substance injection. Therefore, we suggest that lovastatin promotes disc repair and can be used as a potential therapeutic agent for biological repair of disc degeneration after the diagnostic discography procedure.