FIG. 4.

Postirradiation removal of UVB-induced CPDs in HSE-DED constructs. CPDs in the nuclei of HSE-DED keratinocytes irradiated with two MED UVB over 5 days were detected using immunohistochemical analysis (A). The HSE-DED constructs were then returned to culture conditions and sampled every 24 h to test for the presence of UVB-induced DNA damage. From days 0 to 5 after UVB exposure, there was an observable decrease in the number of CPD-positive keratinocytes in the epidermal layer of the HSE-DED. Keratinocytes harboring CPDs in the HSE-DED postirradiation were quantified using image analysis (B). The graph represents the mean ratio of immunopositive cells to total cell nuclei in five microscopy fields per sample±SEM. At days 2 to 5, there was a statistically significant (p<0.05) decrease in the proportion of CPD-positive cells (compared with day 0). The data presented are representative of results obtained using three independent tissue donors (n=3). HSE-DEDs were constructed in triplicate for each time point sampled. The scale bar represents 50 μm in length. Asterisks represents statistical significance of p<0.05. Color images available online at www.liebertpub.com/tec