Pro‑differentiating compounds for human intervertebral disc cells are present in Violina pumpkin leaf extracts

The intervertebral disc degeneration (IDD) is closely associated with inflammation, oxidative stress and loss of the discogenic phenotype which current therapies are unable to reverse. Here, the effects of acetone extract from Violina pumpkin (Cucurbita moschata) leaves on degenerated intervertebral disc (IVD) cells was investigated. IVD cells were isolated from degenerated disc tissue of patients undergoing spinal surgery, and exposed to acetone extract and three major thin layer chromatography subfractions. We found that the cells benefit from exposure in particular to subfraction 7 consisting almost entirely of p-Coumaric acid. Subfraction 7-treated cells showed a significant increase of discogenic transcription factors (SOX9, TRPS1), extracellular matrix components (aggrecan, collagen type II), cellular homeostasis and stress response regulators (FOXO3a, Nrf2, SOD2, SIRT1). Migratory ability and the expression of OCT4, two important markers related to the presence and activity of stem cells also increased. Moreover, subfraction 7 counteractes H2O2-triggered cell damage preventing in particular the increase of the pro-inflammatory and antichondrogenic microRNA, miR-221. This strengthens the hypothesis that adequate stimuli can support resident cells to repopulate the degenerate IVD and restart the anabolic machinery. Taken together, the data we obtained contribute to the discovery of molecules potentially effective in slowing the progression of IDD, a disease for which there is currently no effective treatment. Moreover, the enhancement of a part of plant, the pumpkin leaves, considered a waste product in the Western world, demonstrating that it contains substances with potential beneficial effects on human health.