In vivo iron chelation reduces porphyrin overload and prevents skin photosensitivity in CEP mice. (A) Percentage of RBCs accumulating porphyrins (fluorocyte count) in the peripheral blood of WT and CEP mice treated with DEF 1 or 3 mg/mL in drinking water for 26 consecutive weeks (n = mice number in each group). (B) Porphyrin content in RBCs and bone marrow (BM) cells. Results are expressed as mean ± SD of individual mice (□) in each group. (C) Urinary porphyrin content (uroporphyrin [Uro] isomer I + III, heptacarboxyl porphyrin [Hepta], hexacarboxyl porphyrin [Hexa], pentacarboxyl porphyrin [Penta], and coproporphyrin isomer I [Copro I] or III [Copro III]). Results are expressed as mean ± SD of individual mice with respective contribution of each porphyrin (□). (D) Hepatic porphyrin content. Results are expressed as mean ± SD of individual mice (□). (E) Percentage of fluorocytes in WT and CEP mice treated with DEF 1 or 3 mg/mL on euthanasia (26 weeks). Circles represent individual mice and skin photosensitivity (severe, mild, moderate, and absent). (F) To evaluate skin photosensitivity, mice were depilated and exposed to UVA irradiation (8 J/cm²). We evaluated the severity of skin photosensitivity 5 days after irradiation, and representative macroscopic pictures of dorsal skin are shown. (G) Representative liver and spleen histologic sections from WT, CEP, and CEP mice treated with DEF 3 mg/mL at euthanasia (26 weeks). Sections were stained with hematoxylin/eosin for structural analysis. We observed many porphyrin deposits (brown pigments, black arrow) and clusters of erythroblasts (white arrow) in control CEP mice compared with WT or CEP treated with DEF 3 mg/mL. Histologic sections were analyzed with a Nikon Eclipse Ni microscope (×20). Scale bar, 100 μM. Pictures were captured by using a digital camera (Nikon DS Ri2) and analyzed with NIS Elements AR software. *P < .05 vs untreated CEP mice; §P < .05 vs CEP mice treated with DEF (1 mg/mL).