Effect of balloon withdrawal injury on aortic cell apoptosis and Fas/Bcl-2 gene expression in rats

Objective To investigate the effect of balloon withdrawal injury on aortic cell apoptosis and Fas/Bcl-2 gene expression in rats.Methods Thirty SD male rats were randomly divided into 2 groups: Group 1(n=24) received balloon induced endothelium denudation in the thoracic aorta and were respectively sacrificed at day 2,7,14,28 after artery injury;Group 2(control group,n=6) received no injury procedure and were sacrificed 28 days after procedure.After the thoracic aorta were harvested,immunohistochemistry staining was performed to measure the protein expression of proliferation cell nuclear antigen(PCNA) and Fas/Bcl-2 gene.Vessel morphological measurements were also taken.Results In normal rat arteries,PCNA was not detected.After balloon injury,the proliferation of vascular smooth muscle cells(VSMCs) in media reached its peak at day 2 and then decreased quickly,while in neointima,VSMCs proliferated extremely at day 7 and then decreased.At day 28 after balloon injury,remarkable neointima and luminal narrowing were found.After balloon injury,the expression of Fas gene was accorded with the apoptosis rule measured by TUNEL method.The peak time of apoptosis(7d in media,14 d in neointima) was posterior to the peak time of proliferation(2 d in media,7 d in neointima).After 14 days the apoptosis and proliferation decreased quickly.After balloon injury,Bcl-2 expression in media reached the lowest level at day 7 and then up-regulated;while Bcl-2 expression in neointima reached the lowest level at day 14.The expressions of Fas and Bcl-2 were in a remarkable negative correlation(r=-0.878,P0.001).Conclusions After artery balloon withdrawal injury,there was regular change of apoptosis,which maybe play an important role in the process of luminal narrowing.