Effect of γ radioactive stent on proliferation and apoptosis of smooth muscle cells

AIM: To observe effect of γ radioactive ［103Pd］ stent on the proliferation and apoptosis of smooth muscle cells, the mechanism of radioactive stent preventing in-stent restenosis was explored. METHODS: Fifty male New Zealand rabbits were randomized into stent group and ［103Pd］ stent group. Control group was set up. The materials were harvested on 3, 7, 14, 28, 56 days after operation and the following investigation were carried out, including pathomorphology, immunohistochemistry, apoptosis (TUNEL) and in situ hybridization studies.RESULTS: ① The severity of the stenosis in ［103Pd］ stent group was less severe than that in stent group. It was most obvious on 56 th day (P<0.01). ② The expression of proliferating cell nuclear antigen(PCNA) of ［103Pd］ stent group was lower than that in stent group on 3 to 28 days. It was most obvious on 7th day, 16.35%±0.79% vs 24.36±0.55% (P<0.01). ③ TUNEL method showed that the ［103Pd］ stent group had much more apoptosis of VSMC than that in stent group. The highest rate of apoptosis appeared on day 7, 14.72%±0.53% vs 12.42%±1.13% (P<0.01). ④ By calculating the ratio of PCNA/apoptosis (P〖KG*6〗∶〖KG-*2〗A), a much lower ratio was seen in ［103Pd］-stent groups than that in stent group at 3 to 28 days. There was significant statistic difference (P<0.05). ⑤ For bcl-2/bax ratio, the result in ［103Pd］-stent group was lower than that in stent group at 3 to 28 days. There was significant statistic difference (P<0.05).CONCLUSION: γ radioactive stent inhibits the proliferation and accelerates apoptosis of injured media vascular smooth muscle cells. It decreases the ratio of proliferation to apoptosis and relieves the severity of restenosis.