Ricetti Mm

The effect of ticlopidine on human endothelial cells in culture

The effect of ticlopidine at various concentrations (150, 30, 6 microM), has been studied on cultured endothelial cells derived from human umbilical cord vein. Ticlopidine affects the initial attachment of endothelial cells to artificial substrata and has an inhibitory effect on endothelial cell growth rate which correlates to the concentration of the chemical in the culture medium. These effects are related to a marked reduction of intra- and extracellular fibronectin as evidentiated by immunofluorescence. The drug seems to interfere with the formation of fibronectin filaments from intracellular granules. The reduction of fibronectin availability could affect platelet adhesion to subendothelium as well as endothelial cell repair, and subsequently influence the bleeding time. The inhibition of cell proliferation and its possible effect on the thickness of the vessel wall should be considered as additional mechanisms of action for this substance.

Nicotine alters fibronectin and factor VIII/vWF in human vascular endothelial cells.

Summary. Primary cultured human endothelial cells derived from umbilical cord vein were exposed during the growth of the culture to medium containing nicotine at various concentrations (0.5‐200 μg/ml). Patterns of cellular fibronectin and factor VIII/vWF were compared to control by immunofluores‐cence technique. The levels of glycoproteins released in the culture medium were quantified by ELISA method. Treated cells showed an important decrease in fibronectin content with fragmentation of the fribronectin pericellular filaments, whereas the levels of secreted fibronectin were reduced in a dose‐dependent manner. This reduction of fibronectin availability was correlated with an elongation of cell shape as revealed with phase contrast microscopy. By immunofluorescence, factor VIII/vWF cytoplasmic granules appeared drastically reduced whereas the secretion of the protein was significantly increased. As shown by electron microscopy, there was a concomitant reduction in the number and size of Weibel‐Palade bodies. These studies indicate that nicotine modifies fibronectin and factor VIII/vWF distributions but in different ways.