The Natural Polyphenol Epigallocatechin Gallate Protects Intervertebral Disc Cells from Oxidative Stress

Figure 1

In vitro model system of stress-induced premature senescence. Sublethal oxidative stress (50 μM H₂O₂) with subsequent recovery period activated premature senescence of IVD cells in vitro. (a) Percentage of SA β-gal-positive cells in the H₂O₂ treatment group gradually increased during 15 days after stress (). (b) Upper part: representative images of SA β-gal staining of the untreated (ctrl) and the H₂O₂-treated cells on day 8 after stress, showing senescent (blue) cells. (b) Lower part: representative images of reseeded cells on day 9, confirming general cellular fitness. (c) Phosphorylation of p53 (Ser15) and expression of p21 in the H₂O₂ treatment group on day 15 after stress indicated cellular senescence. ((d), (e)) Proliferative capacity, displayed as number of cells on days 8 and 15 after stress, was reduced in the H₂O₂ groups. On day 15, the number of cells in the H₂O₂ treatment group decreased below the seeding number (1 × 10⁵ cells per well, depicted as red line), suggesting ongoing cell death. Asterisks indicate statistical significance at (ANOVA, Tukey post hoc, and Student’s -test).

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