Proliferation and C-myc Gene Expression of Smooth Muscle Cells in Rabbit Carotid Artery after Stenting

Objectives To investigate the proliferation of smooth muscle cells (VSMCs) and the expression of c-myc gene in rabbit carotid arteries after stenting. Methods Platinium-Iridium stent were implanted into the fight carotid arteries of 16 rabbits under vision. 7,14,30 and 90 days after the stenting procedure, morphological changes of VSMCs were observed under light and transmission electron microscope. The c-myc gene expression was detected by insitu hybridization (ISH) and immunohistochemical staining. Results 7 days after stenting, the phenotype of VSMCs changed from contractile to synthetic phenotype; there were a number of proliferative VSMCs in the neointima. At 14 and 30 days, there were synthetic and transitive VSMCs. At 90 days, the phenotype of VSMCs recovered to contractile phenotype. The ultrastructure of typical synthetic phenotype of VSMCs were round, containing a large amount of rough endoplasmic reticulum and mitochondria. Cmyc expression were positive both by ISH and im-munohistochemical staining. Conclusions C-myc gene expression increases and closely relates to VSMCs proliferation after stenting. It may play an important role in the in-stent restenosis.