以ED-A(+)Fn为靶点超声纳米分子成像及靶向治疗心脏移植慢性排斥反应

Chronic rejection (CR) post heart transplantation is the greatest obstacle that heart transplanation is facing presently. CR is a mutiple factor disease with the main pathologic characteristics of cardiac allograft vasculopathy and cardiac interstitial fibrosis. Its diagnostic modalities, including intravascular ultrasound, angiography and endomyocardial biopsy, all have obvious limitations, and its early therapy is difficult, being low in the sensitivity and the personalization, so there is an urgent need for a new method that combines early diagnosis and personalized therapy to a new target. ED-A+Fn is specifically expressed in the transplanted heart with CR and exerts important function in the development of CR, having a high affinity human recombinant antibody SIP-F8. Based on the previous researches, this study tries to prepare the nanoscale ultrasonic microbubbles carrying SIP-F8, realize the molecular imaging of CR targeting to ED-A+ Fn in myocardium in a rat heart transplantation model, introduce siRNA to down-regulate ED-A+ Fn expression with the microbubbles as the carrier and evaluate its effect on inhibiting CR, providing a new effective way for the early diagnosis, dynamic monitoring and personalized treatment of CR post heart transplantation.

心脏移植后慢性排斥反应（CR）所导致的移植物失活是目前心脏移植面临的最大难题。CR是一种以移植物弥漫性血管病变与心肌间质纤维化为主要病理特点的多因素疾病，其主要临床诊断手段包括血管内超声、血管造影、心肌心内膜活检等检查方法均具有明显的局限性，治疗上也无法达到早期、敏感及个性化，亟需一种能早期诊断并能以之为靶点和通路进行个性化治疗的新方法。ED-A+纤维连接蛋白胚胎剪接变体（ED-A+Fn）在CR移植心脏中特异性高表达且具有重要的功能性作用，还具有高亲和力的人重组抗体SIP-F8。结合前期研究基础，本课题拟制备携SIP-F8的纳米级超声微泡造影剂，以心肌内ED-A+Fn为靶点实现大鼠心脏移植CR超声分子成像，并以该微泡为载体携载ED-A+Fn-siRNA，靶向下调ED-A+Fn水平，评价其抑制CR的效果，为心脏移植后CR的早期诊断、动态监测与个性化治疗探索一种简便、安全的新方法。

慢性排斥反应（chronic rejection，CR）是心脏移植病人最终死亡的主要原因之一。目前临床上对心脏移植后CR的早期诊断和治疗尚不能令人满意。本研究针对心脏移植后 CR 的病理特点，利用利用冷冻干燥法成功制备靶向EDA+Fn的纳米级靶向超声微泡造影剂，粒径约 270nm 左右，具有良好的与活化肌成纤维细胞的体外结合能力。并建立大鼠心脏同系与同种异体移植CR模型，并以靶向EDA+Fn纳米微泡为分子探针，实现大鼠心脏移植CR超声分子成像。时间强度曲线研究发现 CR 超声分子成像峰值强度（PI）和曲线下面积（AUC）均显著升高（P＜0.01），证明超声分子成像可反映移植心肌内EDA+Fn的表达，从而提示CR的发生。在此基础之上，本研究以靶向纳米微泡携载EDA+Fn-siRNA治疗大鼠心脏移植后CR，发现治疗后CR心肌超声分子成像PI和AUC值明显低于未治疗组，证明该技术可有效抑制EDA+Fn的表达，从而抑制CR的发展。该技术为心脏移植CR 的诊断与治疗提供了一条无创、简便、高效的新途径，有助于提高心脏移植患者的生存寿命。