Galectin-7及Galectin-7-siRNA超声靶向微泡在心脏移植急性排斥反应检测及治疗中的实验研究

Acute rejection (AR) is one of the most important factors which affects the survival rate of patients underwent cardiac transplantation. The current clinical diagnosis of AR is mainly through cardiac function test, while it is less sensitive to early rejection. Therefore, it is hard and urgent problems to find out an early, noninvasive diagnosis for AR after heart transplantation, and to monitor its occurrence, development and prognosis. During AR, Galectin-7 protein specified expressed on the surface of vascular endothelial cells and infiltrating T lymphocytes, promoted proliferation of T lymphocyte and induced Th1 / Th2 balance to shift to Th1 cells advantage response. Thus the occurrence and development of transplant rejection was promoted. In this study, we would like to establish the heart transplantation model on rats, and Galectin-7 was used as a new target for the diagnosis of AR for the first time. The anti-Galectin-7 nanoscale ultrasound microbubbles were used to detect AR myocardium through ultrasound imaging. The microbubbles were then used to be the carrier of Galectin-7-siRNA, combined with UTMD technology to mediate the down regulation of Galectin-7through siRNA. Thus the AR was inhibited, and the "double targeting" of diagnosis and treatment to AR after cardiac transplantation was achieved. These studies will lead to a research for early diagnosis, dynamic monitoring and treatment strategies which make Galectin-7 as a target and pathway for AR after heart transplantation.

急性排斥反应（AR）是影响心脏移植患者生存率的重要因素之一，目前临床在体判定AR主要通过心功能测定，对早期排斥反应缺乏敏感性。早期无创有效的诊断心脏移植AR，动态监测其发生发展及预后，成为临床棘手又亟需解决的问题。发生AR时，血管内皮细胞及浸润淋巴细胞表面特异表达Galectin-7 蛋白，促进T淋巴细胞增殖并诱导Th1/Th2平衡向Th1细胞优势应答偏移，促进移植排斥反应的发生发展。本研究拟建立大鼠心脏移植模型，首次以Galectin-7作为诊断AR新靶点，应用抗Galectin-7纳米级靶向超声微泡进行超声分子成像检测AR心肌；并进一步以其作为Galectin-7-siRNA 载体，结合UTMD技术，介导siRNA下调Galectin-7的表达从而抑制AR，实现心脏移植AR诊断及治疗的“双靶向”，为心脏移植AR的早期诊断、动态监测及以Galectin-7为靶点和通路的治疗提供实验依据。

心脏移植（Heart Transplantation, HT）是终末期心衰患者唯一有效的治疗方法，术后主要由T-细胞介导的急性排斥反应（Acute Rejection, AR）仍是影响移植患者的心脏功能和长期存活的重要因素之一。Galectin-7蛋白特异性表达于移植器官的血管内皮细胞及浸润淋巴细胞表面，可以促进T细胞的分化和增殖，进而促进移植排斥反应。因此Galectin-7可作为超声靶向微泡结合的新靶点，通过靶向超声成像判定心脏移植排斥反应程度。此外在靶向成像的基础上，通过抑制Galectin-7蛋白的表达而控制移植排斥反应的发展，实现对排斥反应的诊断及治疗的“双靶向”。在本研究中，我们成功制备了载Galectin-7-siRNA纳米级靶向微泡，其粒径约为221nm，其抗体及Galectin-7-siRNA的同时携带率为71%。在体外实验中，结合超声靶向微泡定位释放技术（Ultrasound-targeted microbubble destruction, UTMD），成功将siRNA转染到细胞内。通过构建大鼠腹部异位心脏移植模型，在体内应用靶向超声微泡作为Galectin-7-siRNA载体，结合UTMD技术，介导siRNA下调Galectin-7的表达，证实了通过抑制Galectin-7蛋白的表达可以有效的减轻移植排斥反应。通过超声微泡这种安全、便捷的非病毒载体载入siRNA靶向释放基因，在靶向成像的基础上实现靶向治疗的目的。