Fig. 1

Histology and biomedical analysis of the aortas at day 90 after irradiation. a The sections of the aortas were stained hematoxylin-eosin (H&E), Masson’s trichrome, and Elastin stain and immunostained against myeloperoxidase (MPO). The area of the vascular lesion (fibrosis, inflammation, and MPO staining) was normalized to the total area of the vascular wall and expressed in percentage. The thickness of intima was divided by the full thickness of the vascular wall and expressed in percentage. The irradiated aortas (RT, RT + MSC-C, and RT + MSC-H groups) showed extensive inflammation, diffuse fibrosis, and neointimal formation. In H&E stain, the plenty of inflammatory cells infiltrated to the arterial adventitia. These cells were positive for MPO staining. The elastic fibers that normally appeared as brown and waved lines after elastin staining were decreased in the media and replaced by bright blue collagen fibers in Masson’s trichrome stain. The collagen fibers not only existed in the media layer but spread across the entire arterial wall. The neointima was clearly visible in H&E and Elastin staining. Despite the absence of injury in Sham RT group, the degree of vascular injury was varied among groups with irradiation. The area of inflammation, fibrosis, and MPO staining as well as intimal thickness was greatest in the RT group, less in the RT + MSC-C group, and lowest in the RT + MSC-H group. Eight rats were examined for each group, and the representative section images were shown. Group comparisons were made using the Mann-Whitney test. *P < 0.05. b The RNA levels of TNF-α, TGF-β, and IL-1β in the aortas were measured by quantitative PCR. The assay was repeated three times for each sample, and the RNA level was expressed in the fold change to that of Sham RT group. Group comparisons were made by using Student’s t test. *P < 0.05