The Effect of Cyclosporine and Dexamethasone on Suppression of Medial Thickening after Arterial Injury in Rats

Abstract

Vascular proliferative lesion is one of the most important causes of stenosis and late thrombosis in arterial reconstructions. We studied the effect of cyclosporine and dexamethasone on decreasing the hyperplastic response after experimental arterial injury in rats. Ninety female rats were assigned to one of four groups, each receiving daily subcutaneous injections of either (1) saline (control), or (2) cyclosporine(CYA) 5mg/Kg/D, or (3) dexamethasone (DEXA) O. 1 mg/Kg/D, or (4) CYA 5mg/kg/D and DEXA O. Img/kg/D. Injections were started 1 day before the intimal injury and continued daily for 6 weeks. Arterial injury was created in 90 rats by rotating a Imm coronary dilator in the right common iliac artery. The vessels were harvested 1,4,6 weeks after injury and the thickness of the tunica media was measured. In the control group the injured iliac artery had significant medial thickening when compared to the noninjured (P(O. 0001) 1 week after injury. Injured arteries treated with CYA or DEXA or CYA and DEXA showed significantly less medial thickening when compared to that of control (P(O. 001) but no significant difference was noted among drug treated groups for 1 and 4 weeks of treatment. At 6 weeks, however, medial thickness in the CYA and DEXA group was significantly less than that of the CYA or DEXA group(P( O. 05). These data suggest that CYA and DEXA are effective in suppressing the hyperplatic myointimal reaction to an intimal injury. In addition, these data also provide the evidence that immunological mechanisms may modulate vascular proliferative lesions.