title: Evaluating surface bound rTFPI through an in vitro model of vessel wall injury.
abstract: BACKGROUND
  Injury to the surrounding vessel wall is one of the major reasons for failure of implantable medical devices. The surgical procedure itself or the altered flow conditions after implantation can cause damage to the vessel wall. This damage exposes tissue factor (TF), the initiator of the extrinsic pathway of coagulation. One approach to combat thrombosis is to use an anticoagulant on the surface of the device. The primary aim of this study is to develop a simplified physiologically relevant in vitro model of vessel wall injury to study the mechanisms by which immobilized recombinant tissue factor pathway inhibitor (rTFPI) effectively inhibits TF initiated thrombosis.
  
  
  METHODS
  A two well chamber slide was used for the study. Fibroblasts were cultured on the upstream portion of the slide. Fibroblast cells stimulated with TNF-α acted as a source of surface TF. The downstream portion of the slide was coated with rTFPI. A mixture of FX, FVIIa and calcium was perfused over the slides to generate FXa. Effluent collected at the outlet was used to analyze the inhibition of this surface generated FXa by the rTFPI present downstream.
  
  
  CONCLUSIONS
  Different shear rates and rTFPI densities were used to study this effect. In most cases rTFPI inhibited FXa generated upstream as a function of the wall shear rate and rTFPI dosage (surface density). This study shows the effectiveness of the surface bound inhibitor when FXa is generated from an upstream injury site and the bulk of FXa is near the wall.
authors.affiliation: Illinois Institute of Technology, Chicago, IL, USA.
authors.forename: Fowzia S
authors.initials: FS
authors.lastname: Zaman
authors.forename: Alan E
authors.initials: AE
authors.lastname: Mast
authors.forename: Connie L
authors.initials: CL
authors.lastname: Hall
mesh_terms: D000327:Adsorption; D001777:Blood Coagulation / Q000187:drug effects / Q000502:physiology; D001808:Blood Vessels / Q000187:drug effects / Q000293:injuries* / Q000473:pathology; D002478:Cells, Cultured; D015951:Factor Xa / Q000096:biosynthesis; D065427:Factor Xa Inhibitors; D005347:Fibroblasts; D005898:Glass; D006801:Humans; D055767:Immobilized Proteins / Q000494:pharmacology*; D008074:Lipoproteins / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000494:pharmacology; D013925:Thromboplastin / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D065427:Factor Xa Inhibitors; D055767:Immobilized Proteins; D008074:Lipoproteins; D011994:Recombinant Proteins; C051928:lipoprotein-associated coagulation inhibitor; D013925:Thromboplastin; D015951:Factor Xa