Regulated cell death: Implications for intervertebral disc degeneration and therapy.

As a controllable biological process, regulated cell death (RCD) extensively participates in cellular homeostasis, organismal development, and the pathogenesis of diseases. This review addresses the research gaps by synthesising the findings on the complexity of RCD modes and their role in disc degeneration, and summarises the preclinical strategies to alleviate disc degeneration and promote disc repair by regulating RCD. Background: Intervertebral disc degeneration (IDD) is the major source of chronic low back pain. As a controllable biological process, regulated cell death (RCD) extensively participates in the pathogenesis of IDD. Nevertheless, the initiation and progression of RCD remain unclear, and more importantly, the interaction between different RCD modes during IDD and therapy is far from well understood. Methods: Literature search was performed using "regulated cell death AND intervertebral disc degeneration" in PubMed, Embase, and Web of Science. Meanwhile, relevant findings have been reviewed and quoted. Results: In this review, we discuss the inducing factors of IDD, various modes of RCD in intervertebral disc, the interactions between different RCD modes, as well as the obstacles to achieve disc regeneration. Meanwhile, the research gaps and perspective in studies that targeting RCD are also presented. Conclusion: Increasing evidence demonstrated the presence of different RCD modes in intervertebral disc during the progression of IDD. RCD in the resident disc cells is probably induced by the multiple factors such as abnormal mechanical loading, nutritional imbalance, inflammation microenvironment, circadian rhythm changes, withdraw of hormones, and other biomechanical factors. A better understanding of the fundamental mechanisms and the interactions between different RCD modes might contribute to the rescuing of disc degeneration and development of promising therapeutics. Translational potential statement: The Translational potential of this article. This review aims to demonstrate a better understanding of the fundamental mechanisms governing RCD, which might contribute to the rescuing of disc degeneration and to the development of promising therapeutics in a clinical setting.