Protective effects of heparin against increased permeability of endothelial cells induced by lipopolysaccharide

Objective To evaluate the effects of heparin on the changes in permeability and cytoskeleton of cultured human umbilical vascular endothelial cells (HUVECs) induced by lipopolysaccharide (LPS).Methods HUVECs were cultured in vitro and randomly assigned to blank control group,LPS group,heparin group,and LPS + heparin group,n =8.Cell viahility was determined by methyl thiazolyl tetrazolium (MTT) method.Endothelial permeability was measured with the Transwell chamber models.F-actin of cytoskeletons was assayed with fluorescein isothiocyanate (FITC)-phalloidine.Results Compared with the blank control group,10 mg/L and 100 mg/L of LPS significantly inhibited cell viability (0.695 ± 0.015,0.476 ± 0.030 vs.0.860 ± 0.053,P＜0.05 and P＜0.01 ).Heparin 100 kU/L also inhibited cell viability (0.675 ± 0.030 vs.0.840 ± 0.023,P ＜0.05 ).Increase in permeability of endothelium was induced by 10 mg/L of LPS,and it peaked at 4 hours,there was significant difference compared with blank control group (5.882 ± 0.101 vs.4.489 ± 0.015,P＜0.05 ).At the same time,LPS led to the reorganization of F-actin cytoskeleton and the fiormation of stress fibers.LPS + heparin decreased the increase in permeability of endothelium at 2-12 hours (2 hours:4.382 ± 0.053 vs.5.084 ± 0.129,4 hours:4.528 ± 0.044 vs.5.882 ± 0.101,6 hours:4.381 ± 0.089 vs.5.479 ± 0.125,12 hours:4.447 ± 0.054 vs.4.719 ± 0.080,all P＜0.05 ),and attenuated the reorganization of F-actin and the formation of stress fibers.Conclusion Heparin attenuates LPS-induced increase in permeability of HUVECs and alterations in F-actin organization,thus protects endothelial barrier. Key words: Sepsis; Heparin; Endothelial cell permeability; Cytoskeleton; F-actin