Noggin expression in human nucleus pulposus cells: A comparative study of degenerative and traumatic intervertebral discs

Low back pain (LBP) is a health issue that leads to considerable disability and socioeconomic burdens. The degeneration of the human intervertebral disc (IVD) is a key factor in the pathogenesis of LBP. During disc degeneration, the nucleus pulposus (NP), a critical component of IVD, undergoes significant alterations in structural composition and function. Recent studies have highlighted the importance of various genes in IVD health. Noggin has been described as an essential gene in nucleus pulposus cells (NPCs) and a central role in inhibiting osteogenesis. In this study, we conducted a comparative analysis of Noggin expression in human NPCs from degenerative and healthy IVD. Twenty-six IVD samples (nineteen from degeneration and seven from trauma) were collected to separate NPCs for RNA extraction. Noggin expression was quantified at the transcript level by qPCR to analyze the difference between degenerative and traumatic IVD. Results indicated that Noggin expression was lower in NPCs from degenerated IVD compared to trauma cases. The severity of IVD degeneration correlated with decreased Noggin levels. Traumatic males exhibited higher Noggin expression than traumatic females and those with IVD degeneration. Noggin expression peaked in young adults (18–45 years), decreased in middle age (46–69 years), and rose again in the elderly (over 69 years), but remained lower than in the youth. Furthermore, upper lumbar discs (T12/L1-L2/3) showed higher Noggin levels than lower lumbar discs (L3/4/-L5/S1). This research elucidates valuable insights into the variability of Noggin concerning sex, age, degree of disc degeneration, and disc segment. It provides implications for IVD health and LBP treatment.