Effects of sirolimus upon endothelial thrombotic function of human umbilical vein endothelial cells

Abstract

To explore the effects of sirolimus upon endothelial thrombotic function of human umbilical vein endothelial cells (HUVEC). Sirolimus was added into the in vitro cultured HUVEC at the concentrations of 0 (control), 0.1, 1 and 10 ng/ml. At 2, 4, 8, 12 and 24 h post-incubation, the cells were harvested for determination of tissue factor (TF), plasminogen activator inhibitor (PAI-1), endothelial nitric oxide synthase (eNOS) and thrombomodulin (TM) expression by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. The clotting functions of HUVEC were assayed by an automated coagulation analyzer. Sirolimus induced the expressions of TF and PAI-1 and inhibited the expressions of eNOS and TM in a concentration-dependent manner. The maximal change of mRNA expression was observed at 8 h and remained up to at least 24 h. And the most marked change of protein expression (65% reduction in eNOS expression, 52% reduction in TM, 1.7-fold increase in PAI-1 and 2.8-fold increase in TF) was at 12 h. The clotting time in sirolimus group (89 s ± 9 s) was significantly shorter than that in control group (152 s ± 17 s, P = 0.005). Sirolimus induces endothelial antithrombotic dysfunction and shortens the clotting time through an elevated expression of prothrombotic genes TF and PAI-1 and a lowered expression of antithrombotic genes eNOS and TM. It may be one of mechanisms of thrombosis after the implantation of sirolimus-eluting stents.