Dynamic investigation of leukocyte-endothelial cell adhesion interaction under fluid shear stress in vitro

To establish a method to investigate the dynamic adhesion between leukocytes and human umbilical vein endothelial cells (HUVECs) under definite shear stress. A parallel plate flow chamber system was developed to produce the definite shear stress in vitro. After the cultured HUVECs were loaded in the flow chamber, the circulation solution containing acridine orange (AO)-labeled leukocytes was perfused to flow through chamber at 0.71 dynes/cm(2). In this case, leukocyte-endothelial cell adhesion process was induced. Lipopolysaccharide(LPS) was used as the chemical stimulus and dexamethasone(DXM) was used as the anti-inflammatory reagent. The adhesion process was recorded in videotape by Olympus IX70 fluorescence microscope and CCD-camera. Then the number of adhesion leukocyte, slow and fast rolling velocities of leukocytes on the surface of HUVECs were measured based on the captured images. The number of static adhering and slow rolling leukocytes on the HUVECs treated with LPS was significantly increased by 23.7-fold and 4.1-fold compared with that of the control group. Meanwhile, both the slow and fast rolling velocities of the leukocytes on HUVECs treated with LPS were significantly decreased by 25.6% and 26.1%. When HUVECs were treated with both LPS and DXM, the effect of LPS was inhibited obviously. This developed method can be used in studying ECs adhesion function affected by different chemical and physical stimulus and evaluating the various compounds interfering with cell adhesion.