Ticagrelor increases endothelial progenitor cell level compared to clopidogrel in acute coronary syndromes: A prospective randomized study.

Background: The clinical benefit of ticagrelor compared to clopidogrel in ACS patients suggested off-target property. Such pleiotropic effect could be mediated by circulating endothelial progenitor cells (EPC) which are critical for vascular healing. We aimed to investigate the impact of ticagrelor on EPC in acute coronary syndrome (ACS) patients undergoing percutaneous coronary intervention (PCI).
Methods: We prospectively randomized 106 ACS patients to ticagrelor or clopidogrel. Sub-populations of CD34+ circulating progenitor cells (PC) were analyzed by flow cytometry allowing one to determine the levels of CD34+ PC, CD34+CD45+ Hematopoietic PC, CD34+133+ immature PC and CD34+KDR+ EPC on admission and at 1 month. Changes in PC level were calculated as the difference between 1 month and baseline value.
Results: The 2 groups were similar regarding baseline characteristics including PC numbers on admission. The 2 groups had similar change in overall CD34+ PC and hematopoietic CD34+45+ PC level (p=0.2). On the contrary, when considering CD34+133+ PC and CD34+KDR+ EPC, we observed that patients treated by ticagrelor had a significantly higher increase in levels of these PC subtypes compared to those treated by clopidogrel (0.23 (-0.33; 0.79) vs 0.00 (-0.5; 0.34); p=0.04 and 0.01 (-0.04; 0.05) vs -0.01 (-0.06; 0.03); p=0.02). Changes in the level of CD34+CD133+ PC correlated with platelet activity measured by the VASP index (r=-0.30; p=0.008). By contrast the increase in the level of CD34+KDR+ EPC in the ticagrelor group was independent of platelet activity.
Conclusions: Ticagrelor increases the number of EPC in ACS patients suggesting a benefit on endothelial regeneration that may participate in the pleiotropic property of the drug.
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