Allogeneic platelet lysate activates the SIRT1-PINK1/Parkin pathway: A promising approach for improving mitochondrial function in an in vitro model of intervertebral disc degeneration.

Background: Intervertebral disc degeneration (IVDD) is a common cause of low back pain and spinal issues. Allogeneic platelet lysate (APL) is a blood product for several growth agents. However, only a few studies have revealed that APL can increase autophagy in defective mitochondria by activating the SIRT1-PINK1/parkin pathway while enhancing mitochondrial function to decrease reactive oxygen species (ROS) levels.

Objective: To elucidate the mechanism by which APL mediates mitochondrial autophagy via the SIRT1-PINK1/Parkin pathway in the treatment of IVDD in vitro.

Methods: Pure platelet-rich plasma (P-PRP) was prepared by two-step centrifugation, and APL was prepared via freeze-thaw cycles. The nucleus pulposus cells of New Zealand white rabbits were harvested and grown. After the third generation, four groups of cells were cultured: (1) control group: standard culture conditions; (2) IL-1β group: intervention; (3) APL group: 24-hour IL-1β intervention followed by 24-hour APL treatment; and (4) APL + EX527 group: SIRT1 inhibitor EX527 24-hour treatment after 24-hour IL-1β and APL treatment. After interventions, cell activity was measured by Trypan blue staining. Apoptosis was measured by flow cytometry in each group. Immunofluorescence labeling measured mitochondrial permeability, ROS, and ROS. RT-PCR evaluated autophagy and inflammation-related gene mRNA expression. Western blot analysis revealed the protein levels of these genes. Electron microscopy reveals mitochondrial autophagy.

Results: APL from P-PRP decreased ROS levels in an IVDD in vitro model, mediated autophagy in dysfunctional mitochondria, and alleviated inflammation via the SIRT1-PINK1/Parkin pathway.