Ultra-microstructural changes in iliac artery after bare and magnetic stent implantation in rabbits

Objective To investigate the preventive effect of magnetic stent on coronary restenosis after percutaneous arterial stenting. Methods Twenty rabbits were divided randomly into 2 groups. Bare stent (BS group, n=10) or magnetic stent (MS group, n=10) was implanted in the left iliac artery of the rabbits of the 2 groups, respectively. Aspirin (25mg, qd) was administered orally to the rabbits of both groups from 3 days before stenting until the rabbits were executed. Unfractionated heparin (2500u, qd) was delivered subcutaneously after stenting for 7 days. Five rabbits of each group were randomly selected to be executed at 7 or 30 days. Structural changes in the injured arteries were studied by optical microscopey, transmissive electronic microscopey and immunohistochemistry. Results At 7 days, more myofibroblasts were found migrating from adventitia to tunica media and intima in BS group than in MS group. Inside the media and intima, large amount of smooth muscle cells of synthetic type were observed. At 30 days after stenting, in magnetic group, most uascular smooth muscle cells (SMCs) under the intima had transformed to contractile type and only little extracellular matrix (ECM) was observed around the SMCs; whereas, in BS group, the SMCs remained to be synthetic type and large amount of ECM was observed around the SMCs, which was composed mainly of proteoglycans and glycoproteins. Conclusions Magnetic stent can inhibit proliferation and migration of SMCs and reducing the production of ECM, and therefore, may prevent restenosis after coronary stenting.