The Change of the Expression of the Proliferation Cell Nuclear Antigen and p27 in Rats after Aortic Balloon Withdrawal Injury

Objective To investigate the the process of luminal narrowing, the expression of some cell cycle modulatory factors in rats artery after aortic balloon withdrawal injury. Methods Thirty SD rats were randomly divided into 2 groups.Group 1 (n=6)served as controls and were killed 28 days after procedure.Group 2 (n=24) had balloon induced endothelium denudation at thoracic aorta and were killed at 2,7,14,28 days after artery injury .After the thoracic aorta were harvested, we used immunohistochemistry to measure the expression Level of cyclin dependent kinase inhibitor p27kip1 and proliferation cell nuclear antigen (PCNA). Meanwhile vessel morphological measurement was taken. Results (1)In normal rat arteries p27 was detected. balloon injury,p27 expression in media decreased ,reached the lowest level at day 2 and then upregulated while vascular smooth muscle cell(VSMC) reached peak proliferation at day 2 and then decreased quickly. In neointima , VSMC proliferated extremely at day 7,p27 could be detected at day 14 and 28 when the proliferation of VSMC decreased . As a result at 28d after balloon injury a outstanding noeintima formed, smaller internal or external elastic lamina area and luminal area formed(P(0.01)); (2)The expression of p27 and the cell proliferation were in remarkable negative correlation(P(0.001)).Conclusion The downregulation of p27 while upregulation of PCNA has a important role in the proliferation of VSMC,neointima formation and the luminal narrowing.