Inflammation plays an important role in the pathogenesis of intervertebral disc (IVD) degeneration. The proinflammatory cytokine tumor necrosis factor alpha (TNF-α) has shown markedly higher expression in degenerated human disc tissue compared with healthy controls. Anti-inflammatory treatment targeting TNF-α has shown to alleviate discogenic pain in patients with low back pain. Therefore, in vitro and ex vivo inflammatory models utilizing TNF-α provide relevant experimental conditions for drug development in disc degeneration research. The current method article addressed several specific questions related to the model establishment. (a) The effects of bovine and human recombinant TNF-α on bovine nucleus pulposus (NP) cells were compared. (b) The required dose for an inflammatory IVD organ culture model with intradiscal TNF-α injection was studied. (c) The effect of TNF-α blocking at different stages of inflammation was evaluated. Outcomes revealed that bovine and human recombinant TNF-α induced equivalent inflammatory effects in bovine NP cells. A bovine whole IVD inflammatory model was established by intradiscal injection of 100 ng TNF-α/ cm3 disc volume, as indicated by increased nitric oxide, glycosaminoglycan, interleukin 6 (IL-6), and interleukin 8 (IL-8) release in culture media, and upregulation of MMP3, ADAMTS4, IL-8, IL-6, and cyclooxygenase (COX)-2 expression in NP tissue. However, results in human NP cells showed that the time point of anti-inflammatory treatment was crucial to achieve significant effects. Furthermore, anticatabolic therapy in conjunction with TNF-α inhibition would be required to slow down the pathologic cascade of disc degeneration.
Keywords: 3R; cytokines; inflammation; intervertebral disc; regeneration; spine.
© 2020 The Authors. JOR Spine published by Wiley Periodicals LLC. on behalf of Orthopaedic Research Society.