Irradiation promotes a pro-inflammatory and thrombogenic phenotype of endothelial cells : quantification with real-time video-microscopy in flow conditions
Gaugler M.H., Vereycken-Holler V., Aigueperse J.
4 ème Congrès de la Société Française d'Athérosclérose, Arcachon (France), 2002, 6-8 june.
In this study, we assessed the effect of irradiation on the functionality of EC regarding inflammation and thrombosis processes by investigating interactions of leukocytes and platelets with EC. For that purpose, we developed an in vitro flow chamber with immobilized EC perfused with whole blood to simulate physiological flow conditions.
A glass slide coated with a monolayer of human microvascular endothelial cell-lung (HMVEC-L) irradiated at 10 Gy or not (137Cs source, 0.7 Gy/min) was assembled in a parallel-plate flow chamber and mounted on the stage of an inverted fluorescence microscope. Then, fluorescently-labelled whole blood was perfused over EC at wall shear rates of 25, 75 and 500 s-1 corresponding to those observed in the microvessels which are the most sensitive to ionising radiation. Interactions of EC with leukocytes (rolling, firm adhesion) and platelets (adhesion, thrombi formation) were quantified by image analysis coupled to real-time videomicroscopy.
Flow assay performed 7 or 21 days after irradiation of EC, revealed respectively 4- and 2-fold increases in the number of rolling and firmly adherent leukocytes and a 1.2-fold increase in their mean rolling velocity on irradiated EC as compared to non irradiated EC. In addition, irradiation enhanced platelet adhesion on EC and thrombi formation by a 1.4-2.5 fold, depending on the wall shear rate.
The use of an in vitro flow assay with whole blood allowed showing, in physiological flow conditions, that irradiation affected the functionality of EC by promoting pro-inflammatory and thrombogenic responses, which may contribute to in vivo radiation-induced fibrosis and vascular occlusion.