Increases of thrombomodulin activity and antigen level on human umbilical vein endothelial cells treated with asbestos and man-made mineral fibers

Abstract

The potential influences of crocidolite asbestos fibers and man made mineral fibers (potassium titanate whisker and magnesium sulfate whisker) on a procoagulant System of human umbilical vein endothelial cells (HUVECs) were investigated by measuring the activity and antigen level of thrombomodulin (TM) on the cell surface. Statistically significant increases in both the TM activity and TM antigen level were observed on HUVECs treated with crocidolite asbestos fibers for 48 h and 72 h compared to untreated cells at low concentrations of the fibers which showed no sign of a cytotoxic effect on the cells. An extensive increase in both the TM activity and TM antigen level was also observed on HUVECs treated with potassium titanate whisker or magnesium sulfate whisker for 48 h and 72 h. A statistical analysis revealed that these fibers had almost the same effects on the increases in both TM activity and the TM antigen level of HUVECs treated with the fibers for 48 h and 72 h, but a treatment of magnesium sulfate whisker at more than 1.25 μg/ml for 24 h was slightly more effective in increasing TM activity on HUVECs compared to other fibers (p<0.05). The [3H]leucine incorporation in HUVECs increased when the cells were treated with crocidolite asbestos or man-made mineral fibers (MMMFs), indicating that the increases in TM activity and the TM antigen level on HUVECs directly exposed to those fibers may not reflect the sole induction of anticoagulant activities, but the general cell damage induced by the fibers.