Prevention of occlusive arterial thrombus formation by a single loading dose of prasugrel suppresses neointimal hyperplasia in mice

- Single oral dose of prasugrel markedly reduced neointimal thickening.
- Potent thrombus inhibition might be a promising strategy to prevent hyperplasia.
- MCP-1, ICAM-1 and TGF-β may play important roles in promoting hyperplasia.
- Inhibition of the mRNA expressions might in part contribute prasugrel's efficacy.

The present study examined the effects of prasugrel in a mouse model of thrombosis-induced neointimal hyperplasia. Following carotid artery injury by application of ferric chloride solution, thrombus formation was assessed on Day 1 and neointimal thickening was assessed on Day 21. Single administrations of prasugrel at 0.3-3 mg/kg (p.o.) resulted in a dose-related and sustained inhibition of ADP-induced platelet aggregation through 24 h. Single and multiple (1 and 3 weeks) administration of prasugrel (3 mg/kg loading and 1 mg/kg/day maintenance doses) resulted in a marked inhibition of neointimal thickening in the injured artery. In the dose-response study, a single administration of prasugrel at 0.3-3 mg/kg (p.o.) dose-relatedly inhibited thrombus formation and neointimal thickening on Days 1 and 21, respectively. The degree of neointimal hyperplasia in the injured artery correlated significantly with the thrombus indices, time to occlusion and patency rate. To explore possible mechanisms of inhibition of neointimal hyperplasia by prasugrel, mRNA expression levels of inflammatory and fibrosis markers were determined in injured arteries. Prasugrel treatment resulted in reduced MCP-1, ICAM-1 and TGF-β mRNA levels on Day 2 (24 h after the injury) and Day 8 (1 week after the injury) in the target arteries. In conclusion, we found that a single oral loading dose of prasugrel markedly prevented neointimal hyperplasia by inhibiting platelet activation and thrombus formation and was associated with inhibition of the expression of inflammatory and fibrosis markers, including MCP-1, ICAM-1 and TGF-β, in the injured arteries.