Gene therapy to promote thromboresistance: Local overexpression of tissue plasminogen activator to prevent arterial thrombosis in an in vivo rabbit model

Tissue-type plasminogen activator (tPA) catalyzes the rate-limiting initial step in the fibrinolytic cascade. Systemic infusion of tPA has become the standard of care for acute myocardial infarction. However, even the relatively short-duration protocols currently employed have encountered significant hemorrhagic complications, as well as complications from rebound thrombosis. Gene therapy offers a method of local high-level tPA expression over a prolonged time period to avoid both systemic hemorrhage and local rebound thrombosis. To examine the impact of local tPA overexpression, an adenoviral vector expressing tPA was created. The construct was characterized functionally in vitro, and the function of the vector was confirmed in vivo by delivery to the rabbit common femoral artery. Systemic coagulation parameters were not perturbed at any of the doses examined. The impact of local overexpression of tPA on in vivo thrombus formation was examined subsequently in a stasis/injury model of arterial thrombosis. The construct effectively prevented arterial thrombosis in treated animals, whereas viral and nonviral controls typically developed occluding thrombi. This construct thus offers a viable technique for promoting a locally thromboresistant small-caliber artery.

组织型纤溶酶原激活剂（tissue-type plasminogen activator，tPA）可催化纤溶级联反应中的限速起始步骤。目前，tPA全身输注已成为急性心肌梗死的标准治疗方案。然而，即便采用当前使用的相对短时长给药方案，仍会出现严重的出血并发症，以及反跳性血栓形成相关并发症。基因治疗可实现长时间的局部高水平tPA表达，从而规避全身性出血与局部反跳性血栓形成两大问题。为探究局部tPA过表达的影响，研究人员构建了表达tPA的腺病毒载体。该构建体完成了体外功能学表征，并通过兔股总动脉递送实验在体内验证了载体的功能。在所检测的所有剂量下，全身凝血参数均未出现异常波动。随后，研究人员通过动脉血栓形成的瘀滞/损伤模型，探究了局部tPA过表达对体内血栓形成的影响。结果显示，该构建体可有效预防受试动物的动脉血栓形成，而病毒载体与非病毒载体对照组通常会形成闭塞性血栓。综上，该构建体为构建局部抗血栓形成的小口径动脉提供了一种可行的技术方案。