Endovascular brachytherapy for the prevention of neointimal hyperplasia in a rabbit restenosis model

Objective In an animal model of restenosis the effect of intravascular brachytherapy with a 188Re filled balloon catheter was investigated. Methods In 16 New Zealand white rabbits, after endothelial denudation of the two iliac arteries with 2.5 mm balloon catheter, endovascular irradiation was performed on either one of the two denuded iliac arteries with another 188Re filled 2.5 mm balloon catheter using different doses (0, 8,15 Gy at 0.05 mm from the surface of balloon) leaving the other one untreated as the control. Then 4 weeks after the intervention, the rabbits were sacrificed and the vessels were excised. For morphologic examinations the tissue sections were stained with HE and van Gieson staining. Smooth muscle cells (SMCs) were identified immunohistologically with an antibody against α-acting. The indexes of stenosis and proliferation were determined by image analysis system. Results The stenosis indexes of the control (0 Gy), 8 and 15 Gy groups were 0.49±0.06, 0 65±0.05, 0.82±0.05, respectively, and the proliferation indexes of the control, 8 and 15 Gy groups were 0.54±0.09, 0.48±0.06, 0.33±0.04, respectively. Neointimal hyperplasia was significantly lower at 15 Gy group (P0.05) whereas at 8 Gy group the proliferation index did not differ significantly from the control group. Almost all neointimal consisted of SMCs as detected by α-acting staining. Conclusion At a radiation absorbed dose of 15 Gy at 0.05 mm from the surface of balloon, catheter transmitted endovascular irradiation with the liquid 188Re after endothelial denudation is feasible and effectively reduces neointimal hyperplasia in rabbit model.