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

Background: Carotid stenting stimulates intimal proliferation through platelet and stem cell activation.
Objective: 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.
Methods: 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.
Results: 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.
Conclusions: Pre-stenting clopidogrel loading dose leaded to short-time modification of endothelial progenitor cells and platelets and to long-term a minor neointimal hyperplasia.