Figure 4. Characterization of young, intermediate-age and senescent HUVECs. Bar chart showing cumulative population doubling (CPD) (a), SA-β-gal activity (%) (b), p16INK4a relative expression reported as fold changes vs. young cells (c) and telomere length (T/S) reported as fold changes vs. young cells (d), in young, intermediate age and senescent HUVECs. *GLM, p<0.05.