Tonda R, Lopez-Vilchez I, Navalon F, Pino M, Hernandez M R, Escolar G, Galan A M
Service of Hemotherapy-Hemostasis, Hospital Clinic, CDB, IDIBAPS, UB, Barcelona, Spain.
Eur J Clin Invest. 2008 Jan;38(1):34-42. doi: 10.1111/j.1365-2362.2007.01899.x.
While procoagulant activities of Tissue Factor (TF) have been widely investigated, its possible pro-adhesive properties towards platelets have not been studied in detail.
We explored the interaction of platelets with human Tissue Factor (hTF) firmly adsorbed on a synthetic surface of polyvinilidene difluoride (PVDF) using different shear rates. For studies at 250 and 600 s(-1), TF firmly adsorbed was exposed to flowing anticoagulated blood in flat perfusion devices. Deposition of platelets and fibrin were evaluated by morphometric, immunocytochemical and ultrastructural methods. Prothrombin fragment 1 + 2 (F1 + 2) levels were also measured. Experiments at 5000 s(-1), were performed on the Platelet Function Analyzer (PFA-100) with experimental cartridges with collagen (COL) or collagen-hTF (COL + TF). Haemostatic effect of recombinant activated FVIIa (rFVIIa) was assessed in the same experimental settings.
Platelet deposition on hTF reached 19.8 +/- 1.3% and 26.1 +/- 3.4% of the total surface, at 250 and 600 s(-1), respectively. Fibrin formation was significantly higher at 250 s(-1) than at 600 s(-1) (P < 0.05). The addition of rFVIIa did not influence platelet deposition but raised fibrin formation and thrombin generation at both shear rates (P < 0.05). At 5000 s(-1), closure times (CT) in the PFA-100 were significantly shortened in the presence of hTF (154.09 +/- 14.69 s vs. 191.45 +/- 16.09 s COL alone; P < 0.05). Addition of rFVIIa did not cause a further reduction of CT.
Our studies demonstrate that hTF is an adhesive substrate for platelets and suggest that the von Willebrand factor could mediate these interactions. At low and intermediate shear rates, rFVIIa enhanced the procoagulant action of hTF, but this effect was not observed at very high shear rates.
虽然组织因子（TF）的促凝血活性已得到广泛研究，但其对血小板可能的促黏附特性尚未得到详细研究。
我们使用不同的剪切速率，探讨了血小板与牢固吸附在聚偏二氟乙烯（PVDF）合成表面上的人组织因子（hTF）之间的相互作用。对于250和600 s⁻¹的研究，将牢固吸附的TF暴露于平板灌注装置中的流动抗凝血液中。通过形态计量学、免疫细胞化学和超微结构方法评估血小板和纤维蛋白的沉积。还测量了凝血酶原片段1 + 2（F1 + 2）水平。在5000 s⁻¹下的实验，是在血小板功能分析仪（PFA - 100）上使用含有胶原蛋白（COL）或胶原蛋白 - hTF（COL + TF）的实验盒进行的。在相同的实验设置下评估重组活化FVIIa（rFVIIa）的止血效果。
在250和600 s⁻¹时，hTF上的血小板沉积分别达到总表面的19.8±1.3%和26.1±3.4%。在250 s⁻¹时的纤维蛋白形成明显高于600 s⁻¹时（P < 0.05）。添加rFVIIa不影响血小板沉积，但在两种剪切速率下均增加了纤维蛋白形成和凝血酶生成（P < 0.05）。在5000 s⁻¹时，在hTF存在下，PFA - 100中的封闭时间（CT）显著缩短（154.09±14.69 s对单独COL时的191.45±16.09 s；P < 0.05）。添加rFVIIa并未导致CT进一步缩短。
我们的研究表明hTF是血小板的黏附底物，并提示血管性血友病因子可能介导这些相互作用。在低和中等剪切速率下，rFVIIa增强了hTF的促凝血作用，但在非常高的剪切速率下未观察到这种效果。
