Intravenous release of NO from lipidic microbubbles accelerates deep vein thrombosis resolution in a rat model

The experiment was designed to analyze whether and how nitric oxide (NO) microbubbles facilitates deep vein thrombosis (DVT) resolution in a rat model.

DVT was induced by ligation of the inferior vena cava (IVC) and left common iliac vein (LCIV) in a rat model. The rats were sacrificed at day 2 and day 8 after ligation. NO was wrapped in lipidic microbubbles which were injected (1.6ml/kg) via tail vein twice a day. Thrombi isolated from IVC were measured by weight (g) and weight length ratio (g/cm).The histological analysis of LCIV indicated that platelets and inflammatory cells aggregation were reduced. The expression of vascular cell adhesion molecule-1 (VCAM-1) was quantified by immunohistochemical (IHC) staining and western blot. The coagulation functions including prothrombin time (PT), thrombin time (TT),activated partial thromboplastin time (APTT) and fibrinogen (FIB) were tested as well.Vein walls from IVC were processed by real-time polymerase chain reaction (RT-PCR) for several endothelial genes including matrix metalloproteinases-2 (MMP-2), matrix metalloproteinases-9 (MMP-9), thrombomodulin (TM), and endothelial nitric oxide synthase (eNOS). The thrombus weight and the expression of VCAM-1 significantly decreased after NO microbubbles treatment. The expression of these endothelial genes were significantly up-regulated by NO micribubbles. There was no statistical difference among the groups in terms of PT, APTT, and TT.

NO microbubbles significantly facilitate DVT resolution in a rat model. The antithrombotic properties of NO microbubbles may be associated with reduced platelets and inflammatory cells aggregation, enhanced collagen turnover and stimulus to an anticoagulant condition of endothelium.