超声预警慢性肺动脉高压肺小动脉原位血栓及携RGDS载尿激酶微泡靶向溶栓的实验研究

Situ-thrombosis in pulmonary arterioles is one of prominent and common pathological findings in chronic pulmonary hypertension, which is hard to diagnose and a crucial factor for prognosis. At present, oral anticoagulants are frequently employed as therapeutic modality but with high bleeding risk. Given noninvasive early warning and early intervention in situ-thrombi in pulmonary arterioles by the thrombus-targeted and high-concentration drug release, the effect of the thrombolytic therapy would be significantly enhanced. Studies have showed that drug-loading targeted ultrasound contrast agent can effectively dissolve systemic fresh thrombus, yet there is no report on thrombolysis for situ-thrombosis in pulmonary arterioles. Therefore, this study is designed to explore the value of echocardigraphic parameters of pulmonary hemodynamics and right heart function in predicting situ thrombosis in pulmonary arterioles, by establishing rabbit model of pulmonary hypertension injected with Monocrotaline, combined with monitoring changes in plasma D-dimer and fibrinogen among blood coagulation-fibrinolysis system, pulmonary arterial pressure through right heart catheterization, and pathological tests on the lung tissue. And then, the availability of vivo thrombolysis of targeted liposome microbubbles which carry urokinase and RGDS is further investigated. This is expected to provide novel conception and evidence for early clinical treatment, and greatly promote the thrombolytic therapy of situ-thrombosis in pulmonary arterioles in pulmonary hypertension.

肺小动脉原位血栓是慢性肺动脉高压重要的病理改变之一，诊断难度大且严重影响疾病的转归，目前多采用口服抗凝药物治疗但可能带来出血风险。若能无创性早期预警并早期干预治疗，针对原位血栓定点高浓度释药，定能显著提高溶栓效果。既往有研究表明靶向载药超声造影剂可以高效助溶体循环新鲜血栓，但对肺动脉原位血栓的溶栓未见报道。为此，本研究拟通过建立兔慢性肺动脉高压状态并肺小动脉原位血栓模型，超声心动图监测肺循环血流动力学参数变化及右心功能改变，结合血浆D-二聚体、纤维蛋白原等凝血/纤溶指标水平，右心导管肺动脉测压及肺组织病理学检查，探讨超声预警肺小动脉原位血栓的价值。进而，采用携RGDS载尿激酶靶向脂质体微泡在体溶栓，探讨靶向载药造影剂微泡助溶肺小动脉原位血栓的价值及可能机制，有望为临床早期干预治疗提供新的思路及依据，极大可能推进对肺动脉高压肺小动脉原位血栓的溶栓治疗。

主要研究内容：本课题属基础研究，建立急性/慢性肺动脉高压动物模型，使用载尿激酶靶向递药系统对肺小动脉急性血栓及慢性原位血栓进行溶栓，在建模及溶栓前后，观察凝血/纤溶相关生化指标，超声心动图监测肺循环血流动力学、右心室形态及功能的改变，并结合肺动脉穿刺测压、肺组织病理学检查等，筛选超声预警急性/慢性肺动脉高压肺小动脉血栓形成的主要指标参数，探讨靶向递药系统助溶肺小动脉血栓的价值及可能机制。重要结果及其科学意义：①成功建立兔急性肺栓塞模型，发现栓子大小是影响右心室功能的重要因素，右室等容收缩加速度（超声心动图参数）能敏感地反映右心室功能改变，可作为右室功能无创评价指标；②成功制备载尿激酶靶向血栓的造影剂微泡及脂质体，发现靶向脂质体溶栓效果优于造影剂微泡，进一步对靶向脂质体进行研究，证明了其在体外和体内的溶栓效果及安全性，靶向脂质体具有作为新型溶栓药物的潜力；③成功探索出超声引导下穿刺肺组织活检及穿刺肺动脉测压的方法，两种检测方法准确性高、可重复性好，可作为动物实验的有效方式。④超声造影对肾动脉狭窄程度及分级的诊断准确性不仅优于多普勒超声，与金标准行数字减影血管造影（DSA）相比也有较好的一致性，具有临床应用价值；研究成果：将研究成果撰写论文12篇，其中2篇被SCI期刊收录、4篇被国家级专业核心期刊收录、4篇正在投稿审理中、2篇在全国超声学术会议上大会交流。培养参与课题研究的硕士研究生12名，已毕业8名，在读4名；培养在读博士研究生4名。