255 - Rivaroxaban enhances thrombin-induced endothelial progenitor cell activation (ID 1364)
Abstract
Background and Aims
Factor Xa (FXa) and thrombin exert non-haemostatic cellular effects. Late-outgrowth endothelial cells (OECs) are a type of endothelial progenitor cells. We investigated the effect of rivaroxaban, a direct oral anticoagulant which specifically inhibits FXa’s activity, on FXa-and thrombin-induced OEC activation, using as activation markers the ICAM-1 membrane expression and MCP-1 secretion.
Methods
CD34+ cells were isolated from cord blood mononuclear cells and appropriately cultured for OEC formation. OECs (passage 4) were incubated with 10μM rivaroxaban (10min), before activation with 50nM FXa or 8U/mL thrombin (24h). OECs were also incubated with 10nM vorapaxar, a specific PAR-1 antagonist (1h), prior to rivaroxaban addition and OEC activation. ICAM-1 expression (MFI values) and MCP-1 secretion (pg/mL/105 cells) were evaluated using flow cytometry and ELISA, respectively.
Results
FXa and thrombin significantly increased ICAM-1 expression by 0.73±0.07 and 2.69±0.47 times, respectively and MCP-1 secretion by 0.59±0.35 and 5.45±3.38 times, respectively. Vorapaxar inhibited FXa- and thrombin-induced ICAM-1 expression (98±3% and 57±1%, respectively) and MCP-1 secretion (95±7% and 54±5%, respectively). Rivaroxaban completely inhibited FXa-induced OEC activation, however enhanced thrombin’s effect. Vorapaxar inhibited the enhancement of OEC activation by rivaroxaban. Specifically, at resting state ICAM-1 expression and MCP-1 secretion were 196.55±83.68 and 705.35±162.43, respectively, thrombin increased them at 513.89±101.52 and 4684.45±1143.80 and rivaroxaban further increased them at 875.38±187.33 and 5819.73±875.18, whereas vorapaxar reduced them at 299.15±63.17 and 1707.21±1029.28, respectively.
Conclusions
This study shows that rivaroxaban inhibits FXa-induced OEC activation, however enhances thrombin’s action, suggesting that this effect is mediated through PAR-1. The underlying mechanism of this effect remains to be established.
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