Balloon angioplasty or stents performed in animal models or in humans helps determine vessel restenosis. The brachytherapy inhibits the proliferation and migration of vascular smooth muscle cells and reduces neointimal formation, and works reducing extracellular matrix synthesis. Many studies showed that the endovascular brachytherapy is usefull for that factors. The purpose of this study is to evaluate the efficacy of Samarium-153 to inhibit intimal neoproliferation (IN) in hypercholestherolemic rabbits by using both an ideal doses and a higher one. Samarium-153 is a gamma and mainly beta emitting radioactive agent. Eighty-six iliac arteries of forty-three hypercholesterolemic rabbits underwent balloon angioplasty injury. They were divided in three different groups: control group (CG = 36), a group submitted to 15Gy irradiation doses (IG 15Gy = 14) and the third group irradiated with 60Gy (IG 60Gy = 36). Quality histological and morphometric (neointimal, media layer and vessel areas) analysis were performed. Blood cholesterol levels (1362 ± 497mg/dl) were measured in the three groups.The most interesting finding was the significant inhibition of IN in the IG 15Gy comparing with CG and IG 60Gy.There was also reduction of the media layer and vessel areas in IG15Gy showing significant difference comparing to other groups. Medium and higher degrees xantomatous cells in the media layer were mostly found in IG 60Gy, as well as hyaline tissue and vascular proliferation. The presence of xantomatous cells as well as the increase of the morphometric size of the vessels were proportional to the lesion levels of the internal elastic layer. These changes were more frequently found in IG 60Gy. As a conclusion, we can state that the IG 15Gy was effective to inhibit the IN while the IG 60Gy was not. The IG 60Gy presented histological and morphometric changes similar to those of vascular radio injury.
Vascular radio injury; Brachytherapy; Samarium-153; Xantomatous cells
