How Cigarette Smoke Affects Spinal Discs

Low back pain affects 80% of individuals over 50 and is increasingly prevalent among younger adults aged 20-40. A major contributor is intervertebral disc (IVD) degeneration, which is accelerated by cigarette smoking. However, the mechanisms underlying smoking-induced degeneration remain unclear, and no cure exists, underscoring the need for research to slow disease progression and improve symptom management. This study aims to establish an in vitro IVD organ culture system to investigate the effects of cigarette smoke extract (CSE) on disc cell function and evaluate the protective role of the antioxidant N-acetyl-L-cysteine (NAC). CSE was generated using a syringe-based smoking apparatus and quality-controlled through optical density and nitrite content analysis. Rat spinal discs were cultured under three conditions: control, CSE exposure, and CSE + NAC treatment. A controlled 10% CSE exposure simulated chronic heavy smoking effects in humans, while organ viability was confirmed in controls. Exposure to 10% CSE increased oxidative stress (reactive oxygen species levels), calcification (alkaline phosphatase activity), and apoptosis (caspase-3 activation), particularly in the cartilaginous endplate (CEP), a vulnerable disc-bone interface. Notably, NAC treatment mitigated these effects and preserved cell function. These findings establish CSE-induced oxidative stress as a key driver of IVD degeneration and identify the CEP as a critical target for early diagnosis and pharmacological intervention. By demonstrating NAC's protective effects against CSE-induced damage, this study lays the groundwork for future animal studies, clinical trials, and early drug therapies to preserve disc integrity and function.