Figure 3
DNA damage of RHEs fixated directly (a) and 24 h after UV irradiation (b) and excised human skin (c). The data show the percentage of positive cells with 6-4PP (grey, blue) and CPD damage (red, orange). For both skin models, non-irradiated skin (negative control) shows no damage. In RHEs 44.2% of epidermal cells irradiated with 40 mJ/cm2 at 254 nm (positive control) show CPDs and 21.5% of the epidermal cells show 6-4PPs. In excised human skin, irradiation with 3 mJ/cm2 of UVB (positive control) induced 84.1% CPD positive cells. A reduction in DNA damage of RHEs was observed for fixation 24 h after irradiation with 40 mJ/cm2 at 254 nm (positive control), indicating a DNA repair mechanism (b). The CPD damage after 150 mJ/cm2 irradiation with 222 nm disappeared when fixating 24 h after irradiation. The weak damage after 233 nm irradiation with 80 mJ/cm2 when fixated immediately, disappeared when fixating 24 h later. Consecutive irradiation at 80 mJ/cm2 of 233 nm every 24 h did not show any DNA damage. The presented p-values derive from multiple comparisons with Bonferroni corrections after a Kruskal–Wallis test. Every group was compared to the positive control (a,c) and additionally the influence of multiple irradiations and fixation time was checked (b). The data show mean ± SEM. n = 3–12.
