title: Effect of unfractionated heparin and a low molecular weight heparin (enoxaparin) on coagulant activity of cultured human endothelial cells.
abstract: OBJECTIVE
  Unfractionated heparin and low molecular weight heparins exert their anticoagulant effect by mobilizing tissue factor pathway inhibitor (TFPI) from the vascular endothelium into the blood circulation. We compared the influence of unfractionated heparin and enoxaparin on the anticoagulant function of cultured human endothelial cells.
  
  
  METHODS
  Monolayers of human umbilical vein endothelial cells were treated with 10 U/mL unfractionated heparin or enoxaparin for different periods of time (30min-48h). Endothelial cell procoagulant activity was determined in the cell lysates by a chromogenic assay. Endothelial cell tissue factor (TF) and released TFPI and von Willebrand factor (vWF) was determined.
  
  
  RESULTS
  In short periods of incubation (30min-2h), both heparins reduced endothelial cell procoagulant activity, the inhibition produced by unfractionated heparin being greater than that induced by enoxaparin (p<0.05). However, no variations were observed in TFPI and vWF release. With long periods of incubation (24-48h), both unfractionated heparin and enoxaparin significantly increased TFPI release (control vs. unfractionated heparin, p<0.05-0.001; control vs. enoxaparin, p<0.01-0.001) and also reduced the release of vWF in the culture medium, though no variations in endothelial cell procoagulant activity or TF content were observed.
  
  
  CONCLUSIONS
  Our findings show that unfractionated heparin and enoxaparin exert different kinds of effects on endothelial cells. With short incubation periods, procoagulant endothelial cell capacity was reduced to a greater extent by unfractionated heparin, while after longer periods of incubation enoxapain increased the anticoagulant activity of the endothelial cells to a greater degree than did unfractionated heparin.
authors.affiliation: Centro de Investigación, La Fe University Hospital, Valencia, Spain. martinez_vicsal@gva.es
authors.forename: Vicenta
authors.initials: V
authors.lastname: Martinez-Sales
authors.forename: Virtudes
authors.initials: V
authors.lastname: Vila
authors.forename: Edelmiro
authors.initials: E
authors.lastname: Réganon
authors.forename: Javier Garcia
authors.initials: JG
authors.lastname: Oms
authors.forename: Justo
authors.initials: J
authors.lastname: Aznar
mesh_terms: D000925:Anticoagulants / Q000494:pharmacology*; D001777:Blood Coagulation / Q000187:drug effects; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology*; D017984:Enoxaparin / Q000494:pharmacology*; D006493:Heparin / Q000494:pharmacology*; D006801:Humans; D008074:Lipoproteins / Q000378:metabolism; D013925:Thromboplastin / Q000378:metabolism; D014841:von Willebrand Factor / Q000378:metabolism
chemical_list: D000925:Anticoagulants; D017984:Enoxaparin; D008074:Lipoproteins; C051928:lipoprotein-associated coagulation inhibitor; D014841:von Willebrand Factor; D006493:Heparin; D013925:Thromboplastin