Prophylaxis of Restenosis With ¹⁸⁶ Re-Labeled Stents in a Rabbit Model

Background Intraluminal β-irradiation has been shown to decrease neointimal proliferation after angioplasty in experimental models. The purpose of this study was to test the technical feasibility and biological effects of 186 Re-labeled stents. Methods and Results Thirty-four New Zealand White rabbits were fed a 0.5% cholesterol diet before balloon angioplasty and insertion of Palmaz stents in the infrarenal aorta. The animals were killed 7 weeks after stent implantation. Two of 34 animals died prematurely (aortic leak, pneumonia). Control stents (n=7) were compared with 186 Re stents (2.6 MBq [n=6], 8.1 MBq [n=5], 16.0 MBq [n=6], and 25.3 MBq [n=8]). Stent application was successful in all cases. No thrombus occlusion was observed. After 7 weeks, neointima formation was 2.2±0.2 mm 2 in the control group. In the treatment groups, a dose-dependent neointima reduction was detectable (0.5±0.5 mm 2 [2.6 MBq], 0.4±0.4 mm 2 [8.1 MBq], and 0 mm 2 [16.0 MBq, 25.3 MBq]). No induction of neointimal formation was observed at the edges of the stents. Radiation resulted in delayed reendothelialization. Conclusions 186 Re stents were capable of reducing neointima formation in a dose-dependent fashion. 186 Re stents did not cause late thrombosis or neointimal induction at the stent margins in the observation period of 7 weeks.