Expression of coxsackievirus and adenovirus receptor(CAR) in neointima of the rat carotid artery

Our previous study revealed that the coxsackievirus and adenovirus receptor (CAR) is a homophilic cell adhesion molecule and may function as a sensor of cell-cell interactions in the brain and damaged heart. In this study, we investigated if CAR expression is involved in the formation of neointimal hyperplasia using a balloon injury model of rat carotid artery. Cultured vascular smooth muscle cells (SMCs) from rat aorta were also studied. CAR antigen was constitutively detected in the endothelial cells (ECs) but not in SMCs before injury. On day 5 after balloon injury, CAR was expressed strongly in the first layer of medial SMCs. Neointimal hyperplasia was observed on day 7, and strong expressions of CAR concomitantly with proliferating cell nuclear antigen (PCNA) were obvious in the neointimal SMCs, while CAR in medial SMCs disappeared. The expression of CAR mRNA reached a peak on day 7 and declined gradually to the basal levels. When the ECs regenerated on day 14, CAR antigen was observed in the ECs but disappeared in the neointima. CAR together with PCNA was expressed abundantly in the proliferating SMCs in vitro, and diminished in cells grown to a con fluent state. The abundant expression of CAR in the neointima may facilitate an adenoviral gene therapy