LAUSR

Aims: This study aims to investigate the protective effects and potential mechanisms of cyclosporine A (CsA), which efficiently inhibits mitochondrial permeability transition pore (MPTP) opening, on compression‐induced apoptosis of human nucleus pulposus mesenchymal stem cells (NP‐MSCs). Materials and methods: Human NP‐MSCs were subjected to various periods of 1.0 MPa compression. Cell viability was evaluated using cell counting kit‐8 (CCK‐8) assay. The cellular ultrastructure and ATP level were analyzed via transmission electron microscopy (TEM) and ATP detection kit respectively. The apoptosis ratio was determined using Annexin V/PI dual staining and terminal deoxynucleotidyl transferase‐mediated dUTP nick end labeling (TUNEL) assays. The levels of apoptosis‐associated molecules (cleaved caspase‐3, Bax and Bcl‐2) were analyzed by western blot and qRT‐PCR. Additionally, MPTP opening, mitochondrial membrane potential (MMP) and the levels of oxidative stress‐related indicators (ROS), superoxide dismutase (SOD) and malondialdehyde (MDA) were monitored. Key findings: Annexin V/PI dual staining and detection of apoptosis‐associated molecules demonstrated that compression significantly up‐regulated apoptosis level of NP‐MSCs in a time‐dependent manner. CsA greatly down‐regulated compression‐mediated NP‐MSC apoptosis and the cell death ratio. Compression also notably exacerbated mitochondrial dysfunction, ATP depletion and oxidative stress in NP‐MSCs, all of which were rescued by CsA. Significance: Our results demonstrated that CsA efficiently inhibited compression‐induced NP‐MSCs apoptosis by alleviating mitochondrial dysfunction and oxidative stress. These findings provide new insights into intervertebral disc (IVD) degeneration (IVDD), and suggest CsA treatment as a potential strategy for delaying or even preventing IVDD.