Remodeling with neointima formation in the mouse carotid artery after cessation of blood flow.

The ability of gene targeting in the mouse species presents a powerful tool to determine the role of specific molecules in vascular biology. Using a denuding-injury procedure, we recently reported that intimal lesions can be induced in the carotid artery of outbred mice. The technical challenge associated with achieving complete denudation and the relatively small size of the developing lesions prompted us to design the present model of neointima formation and vascular remodeling in the carotid artery of the inbred FVB mouse strain. Complete ligation of the vessel near the carotid bifurcation induced rapid proliferation of medial smooth muscle cells, leading to extensive neointima formation in the presence of an endothelial lining. Thrombus formation was not observed except in the most distal part of the vessel adjacent to the ligature. At 4 weeks after ligation, luminal area was reduced by approximately 80% through a combination of decreased vessel diameter and neointima formation. Ultrastructural analysis provided evidence for cell death in the developing neointima as well as the remodeling media. The present model might be useful in identifying those genes important for neointima formation and vascular remodeling.