title: Determination of surface tissue factor thresholds that trigger coagulation at venous and arterial shear rates: amplification of 100 fM circulating tissue factor requires flow.
abstract: Protein microarrays presenting spots of collagen and lipidated tissue factor (TF) allowed a determination of the critical surface concentration of TF required to trigger coagulation under flow. Whole blood supplemented with corn trypsin inhibitor (to inhibit factor XIIa) was perfused over microarrays for 5 minutes. Immunofluorescence staining of platelet glycoprotein GPIbalpha and fibrin(ogen) revealed a critical TF concentration (EC50) of 3.6, 8.4, and 10.2 molecules-TF/microm2 at wall shear rates of 100, 500, and 1000 s(-1), respectively. For collagen arrays where only the center lane of spots (in the direction of flow) contained TF, a downstream distance of 14 mm was required for the thrombus to widen enough to reach across a 300-micrometer gap to the adjacent TF-free lanes of collagen spots, in agreement with numerical simulation. To investigate the effect of low levels of circulating TF, whole blood (+/-100 fM added TF) was tested under static and flow conditions. After 5 minutes, the addition of 100 fM TF to whole blood had negligible effect under static conditions, but caused a 2.5-fold increase in fibrin formation under flow. This report defines the threshold concentrations of surface TF required to trigger coagulation under flow.
authors.affiliation: Institute for Medicine and Engineering, Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, USA.
authors.forename: Uzoma M
authors.initials: UM
authors.lastname: Okorie
authors.forename: William S
authors.initials: WS
authors.lastname: Denney
authors.forename: Manash S
authors.initials: MS
authors.lastname: Chatterjee
authors.forename: Keith B
authors.initials: KB
authors.lastname: Neeves
authors.forename: Scott L
authors.initials: SL
authors.lastname: Diamond
mesh_terms: D001777:Blood Coagulation / Q000187:drug effects; D001783:Blood Flow Velocity / Q000187:drug effects; D003094:Collagen / Q000737:chemistry / Q000378:metabolism; D015956:Factor XIIa / Q000737:chemistry / Q000378:metabolism; D005337:Fibrin / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D008955:Models, Cardiovascular; D010940:Plant Proteins / Q000737:chemistry / Q000494:pharmacology; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000737:chemistry / Q000378:metabolism; D040081:Protein Array Analysis; D033081:Shear Strength; D013314:Stress, Mechanical; D013925:Thromboplastin / Q000737:chemistry / Q000378:metabolism*; D013997:Time Factors
chemical_list: D010940:Plant Proteins; D019038:Platelet Glycoprotein GPIb-IX Complex; C052160:trypsin inhibitor, Zea mays; D005337:Fibrin; D003094:Collagen; D013925:Thromboplastin; D015956:Factor XIIa