Timing of clopidogrel loading dose on peripheral blood endothelial progenitor cells, SDF-1α and neointimal hyperplasia in carotid stenting.

Carotid stenting stimulates intimal proliferation through platelet and stem cell activation. The aim of this study is to evaluate whether the administration before or after carotid stenting of clopidogrel loading dose may play a role on circulating endothelial progenitor cells, stromal cell-derived factor-1α (SDF-1α) and neointimal hyperplasia. We recruited 13 patients (aged 74.52±7.23) with indication of carotid revascularization and in therapy with salicylic acid and statin. We blindly randomized them in two groups: pre-carotid angioplasty with stent (Pre-CAS group) receiving 300 mg of clopidogrel before stenting, and post-carotid angioplasty with stent (Post-CAS group) receiving 300 mg after stenting. At the admission, we valued endothelial progenitor cells, SDF-1α and prospectively we repeated blood samples and measured intima-media thickness to estimate neointimal hyperplasia on the stent at 3, 6 and 12 months. In the days following the CAS, we found a lower, statistically not significant, trend of endothelial progenitor cells in Pre-CAS group. The SDF-1α concentration tended to be lower at baseline in the pre-CAS group than in the post-CAS group and it did not show an increase in the observed time. On the contrary, in the Post-CAS group we observed a peak at six hours with a significant reduction (p < 0.001) at one day after stenting.The intima-media thickness was significantly lower in the Pre-CAS group than the Post-CAS group both at six months and 12 months after stenting. Pre-stenting clopidogrel loading dose leaded to short-time modification of endothelial progenitor cells and platelets and to long-term a minor neointimal hyperplasia.