Figure 2. The protective effect of CBLB502 against radiation damage to tissues in the head and neck area of mice.

(A). Mouse body weight changes after 30 Gy local head and neck radiation treatment, with and without CBLB502 (1 µg/mouse, n=6), given in three 10 Gy fractions over three consecutive days. Results representative of at least two analogous experiments are presented. (*) The difference between irradiated groups, with and without CBLB502 treatment, is significant (p<0.05). (B). Upper row. Photographs of irradiated NIH-Swiss mice with or without CBLB502 pretreatment. Lower row. H&E stained skin sections from the neck area. Mice were locally irradiated with 30 Gy X-ray given in three daily 10 Gy fractions. Images were taken on day 14 after the first radiation treatment. Lower row. H&E stained histological sections of the skin sections. (C). H&E stained histological sections of tip, dorsal and ventral epithelium of mouse tongue obtained 11 days after the first of three 10 Gy fractions of 30 Gy total X-ray irradiation. For B (lower panel) and C, H&E stained tissue sections from healthy untreated (u/t) mice were used as a positive control. The pictures of the untreated mice show stratified squamous epithelium with basal layer of small, dark cells from which the mucosa is constatnly renewed and overlaying larger spinous cells and superficial flattened cells. The irradiated and PBS treated mice reveal atrophic and degenerative changes in the basal and overlaying cells with loss of cells, pyknotic and dysplastic nuclei, erosions and hemorrhage. In contrast, the irradiated and CBLB502 treated mice have mucosa with minimal radiation associated changes and morphology closer to the normal, with better preserved, regular basal and overlaying epithelial cells. Tissues from non-irradiated CBLB502-treated animals were histologically indistinguishable from control non-irradiated vehicle-treated animals (data not shown).