Resveratrol attenuates mechanical compression-induced nucleus pulposus cell apoptosis through regulating the ERK1/2 signaling pathway in a disc organ culture

Background: Nucleus pulposus (NP) cell apoptosis is a typical feature within the degenerative disc. High magnitude compression significantly promotes NP cell apoptosis. Several studies have indicated that resveratrol has protective effects on disc cell's normal biology. Objective: The present study aims to investigate whether resveratrol can attenuate mechanical overloading-induced NP cell apoptosis in a disc organ culture. Methods: Isolated porcine discs were cultured in culture chambers of a mechanically active perfusion bioreactor and subjected to a relatively high magnitude compression (1.3 MPa at a frequency of 1.0 Hz for 2 h once per day) for 7 days. Different concentrations (50 and 100 mu M) of resveratrol were added into the culture medium to observe the protective effects of resveratrol against NP cell apoptosis under mechanical compression. The noncompressed discs were used as controls. Results: Similar with the previous studies, this high magnitude compression significantly promoted NP cell apoptosis, reflected by the increased number of terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining-positive NP cells and enzyme (caspase-9 and caspase-3) activity, the up-regulated expression of proapoptotic molecules (Bax and caspase-3/cleaved caspase-3), and down-regulated expression of antiapoptotic molecule (Bcl-2). However, resveratrol partly attenuated NP cell apoptosis under this high magnitude compression in a dose-dependent manner. Additionally, though the ERK1/2 pathway was significantly activated in the mechanical compression group, resveratrol partly attenuated activation of the ERK1/2 pathway under mechanical compression in a dose-dependent manner. Conclusion: Resveratrol attenuates mechanical overloading-induced NP cell apoptosis in a dose-dependent manner, and inhibiting activation of the ERK1/2 pathway may be one potential mechanism behind this regulatory process.