Prophylaxis of restenosis with ¹⁸⁶Re-labeled stents in a rabbit model

Background:

Intraluminal beta-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 ¹⁸⁶Re-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 ¹⁸⁶Re stents (2.6 MBq [n=6], 8.1 MBq [n=5], 16 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 mm² in the control group. In the treatment groups, a dose-dependent neointima reduction was detectable (0.5±0.5 mm² [2.6 MBq], 0.4±0.4 mm² [8.1 MBq], and 0 mm² [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:

¹⁸⁶Re stents were capable of reducing neointima formation in a dose-dependent fashion. ¹⁸⁶Re stents did not cause late thrombosis or neointimal induction at the stent margins in the observation period of 7 weeks.