Fig. 2.

Replication-induced senescence in fibroblasts expanded in PL-supplemented media. Senescence in fibroblasts expanded in 2% and 4% PL, compared to 4% FBS, was quantified by measuring a absolute telomere length and b–f β-galactosidase accumulation in cells. Panels b–e and b’–e’ visualise, weeks 1–2 and weeks 7–8 stained fibroblast cultures, respectively. Panels e’’ and e’’’ present stained fibroblasts from weeks 11 to 12 and weeks 15 to 16 cultures, respectively. Fibroblasts in 4% FBS-supplemented standard media were kept in culture for up to 16 weeks as a reference. Values represent mean values + / − SEM in each group (* = p ≤ 0.05, ** = p ≤ 0.01, *** = p ≤ 0001, n = 5 per group)