A TRPC3 Blocker, Ethyl-1-(4-(2,3,3-Trichloroacrylamide)Phenyl)- 5-(Trifluoromethyl)-1H-Pyrazole-4-Carboxylate (Pyr3), Prevents Stent-Induced Arterial Remodeling s

TRPC-mediated Ca entry has been implicated in the control of smooth muscle proliferation and might represent a pivotal mechanism underlying in-stent restenosis. As we have observed significant expression of TRPC3 in human smooth muscle from the coronary artery as well as the aorta, we tested the efficiency of a recently discovered TRPC3 selective Ca entry blocker Pyr3 to prevent vascular smooth muscle proliferation and stent implantation-induced hyperplasia of human aorta. The effect of Pyr3 on proliferation was measured by detection of BrdU incorporation and PCNA expression in human coronary smooth muscle and microvascular endothelium, which displays significantly smaller expression levels of TRPC3 as compared with smooth muscle. Pyr3 inhibited smooth muscle proliferation but lacked detectable effects on endothelial proliferation. Measurements of ATP-induced Ca signals revealed that Pyr3 suppressed agonist-induced Ca entry more effectively in vascular smooth muscle than in endothelial cells. Inhibitory effects of Pyr3 on stent implantation-induced arterial injury was tested using a novel in vitro model of in-stent hyperplasia in human arteries based on organ typical culture of human aortic constructs. Pyr3 effectively prevented increases in tissue levels of PCNA and Ki-67 at 2 weeks after stent implantation into human aortae. Similarly, proliferation markers were significantly suppressed when implanting a Pyr3-releasing stent prototype as compared with a bare metal stent (BMS) control. Our results suggest TRPC3 as a potential target for pharmacological control of smooth muscle proliferation. Selectively inhibition of TRPC Ca entry channels in vascular smooth muscle is suggested as a promising strategy for instent restenosis prevention.