Dichek D A, Anderson J, Kelly A B, Hanson S R, Harker L A
Department of Medicine, Emory University School of Medicine, Atlanta, Ga 30322, USA.
Circulation. 1996 Jan 15;93(2):301-9. doi: 10.1161/01.cir.93.2.301.
The effects of regulating endothelial cell (EC) plasminogen activator production on thrombus accumulation in vivo are incompletely understood. By overexpressing plasminogen activators in ECs via gene transfer, the hypothesis was tested that increased levels of plasminogen activators inhibit the accumulation of thrombus in vivo.
Cultured baboon ECs transduced with human cDNAs for wild-type tissue plasminogen activator (TPA) or for glycosylphosphatidylinositol-anchored urokinase-type plasminogen activator (a-UPA) were seeded onto collagen-coated segments of vascular graft (collagen segments) and exposed overnight to flow using an in vitro perfusion circuit. The antigenic levels of TPA and UPA each increased 10-fold in the media perfusing the corresponding transduced ECs compared with untransduced ECs (P < or = .05 in both cases). In baboons the antithrombotic effects of TPA-transduced or a-UPA-transduced ECs were measured as 111In-platelet deposition and 125I-fibrin accumulation on collagen segments bearing sparsely attached ECs (tarnsduced versus untransduced) interposed in exteriorized arteriovenous femoral shunts. Platelet-rich thrombus formed on the collagen segments with fibrin-rich thrombus propagated distally. The presence of TPA-transduced or a-UPA-transduced ECs on collagen segments at a density of 25,000 ECs/cm2 decreased 111AIn-platelet deposition and 125I-fibrin accumulation on collagen surfaces compared with untransduced ECs present at equivalent density (P < .05 for platelet deposition with TPA-transduced ECs and P < .05 for platelet deposition on the propagated tail, as well as fibrin accumulation on the graft with a-UPA-transduced ECs). The systemic levels of fibrinopeptide A, thrombin-antithrombin complex, D-dimer, and both local and systemic levels of TPA and UPA were not increased by transduced ECs compared with untransduced ECs. The focal antithrombotic effects of transduced ECs appear to be due to local enhancement of thrombolysis.
ECs transduced with recombinant TPA and a-UPA enhance local antithrombotic activity in vivo. This strategy of attaching transduced ECs overexpressing plasminogen activators may be therapeutically useful by preventing thrombo-occlusive failure of implanted cardiovascular devices or mechanically denuded vessels.
调节内皮细胞（EC）纤溶酶原激活物生成对体内血栓形成的影响尚未完全明确。通过基因转移使EC中纤溶酶原激活物过表达，对纤溶酶原激活物水平升高可抑制体内血栓形成这一假说进行了验证。
将转导了人野生型组织纤溶酶原激活物（TPA）或糖基磷脂酰肌醇锚定的尿激酶型纤溶酶原激活物（α-UPA）cDNA的培养狒狒EC接种到血管移植物的胶原包被段（胶原段）上，并使用体外灌注装置使其过夜暴露于血流中。与未转导的EC相比，灌注相应转导EC的培养基中TPA和UPA的抗原水平均升高了10倍（两种情况均P≤0.05）。在狒狒中，以111铟标记血小板沉积和125碘标记纤维蛋白在插入体外股动静脉分流中、带有稀疏附着EC（转导与未转导）的胶原段上的积聚来衡量TPA转导或α-UPA转导EC的抗血栓作用。富含血小板的血栓在胶原段上形成，富含纤维蛋白的血栓向远端延伸。与同等密度的未转导EC相比，胶原段上密度为25000个EC/cm2的TPA转导或α-UPA转导EC可减少胶原表面的111铟标记血小板沉积和125碘标记纤维蛋白积聚（TPA转导EC的血小板沉积P<0.05，延伸尾部的血小板沉积以及α-UPA转导EC的移植物上的纤维蛋白积聚P<0.05）。与未转导EC相比，转导EC并未使纤维蛋白肽A、凝血酶-抗凝血酶复合物、D-二聚体的全身水平以及TPA和UPA的局部及全身水平升高。转导EC的局部抗血栓作用似乎是由于局部溶栓增强所致。
转导重组TPA和α-UPA的EC可增强体内局部抗血栓活性。附着过表达纤溶酶原激活物的转导EC这一策略可能通过预防植入的心血管装置或机械剥脱血管的血栓闭塞性故障而具有治疗用途。
