Studies of the factor Xa-dependent inhibitor of factor VIIa/tissue factor (extrinsic pathway inhibitor) from cell supernates of cultured human umbilical vein endothelial cells

• Published in: Thrombosis and haemostasis Vol. 61; no. 1; p. 101
• Main Authors: Warn-Cramer, B J, Almus, F E, Rapaport, S I
• Format: Journal Article
• Language: English
• Published: Germany 28.02.1989
• Subjects: Cell Division; Cells, Cultured; Culture Media; Endothelial Growth Factors; Endothelium, Vascular - cytology; Endothelium, Vascular - metabolism; Factor VII - antagonists & inhibitors; Factor VIIa; Factor Xa; Growth Substances - physiology; Heparin - pharmacology; Humans; Lipoproteins; Molecular Weight; Neoplasm Proteins - biosynthesis; Serine Endopeptidases - physiology; Tetradecanoylphorbol Acetate - pharmacology; Thrombin - physiology; Thromboplastin - antagonists & inhibitors; Umbilical Veins - metabolism
• DOI: 10.1055/s-0038-1646535
• ISSN: 0340-6245

Cultured human umbilical vein endothelial cells (HUVEC) have been reported to produce extrinsic pathway inhibitor (EPI), the factor Xa-dependent inhibitor of factor VIIa/tissue factor (TF). We examined the release of this inhibitor from HUVEC as a function of their growth state and in response to the induction of endothelial cell TF activity. HUVEC constitutively produced significant amounts of EPI at all stages of their growth in culture including the post-confluent state. Rate of release varied over a 3-fold range for primary cultures from 12 different batches of pooled umbilical cord cells. Constitutive EPI release was unaltered during a 6 hour period of induction of TF activity with thrombin or phorbol ester but slowed during longer incubation of the cells with phorbol ester. Whereas plasma contains two molecular weight forms of EPI, only the higher of these two molecular weight forms was demonstrable by Western analysis of HUVEC supernatants with 125I-factor Xa as the ligand.