靶向整合素β3分子显像的心肌细胞凋亡调控机制及诊疗一体化研究

It is an ugert clinal difficult problem to be solved for mechanisms of myocardial cell apoptosis, imaging diagnosis, treatment strategy and evaluation. Based on previous study of cardiomyocyte apoptosis PET imaging, we further study the molecular mechanism of myocardial apoptosis and intervention treatment at the level of molecules, cells, tissues and animals, targeting integrin β3, the key factor for the promotion of myocardial proliferation, by using novel imaging tracers and positron emission tomography (PET) imaging technology. We construct H9C2 cells with β3 integrin gene overexpression and silencing and evaluate the effect of β3 integrin on H9C2 apoptosis and apoptosis factor, induced by hypoxia in vitro. In the model of myocardial infarction, 18F-AlF-NOTA-PEG3-β-Glu-RGD2 PET imaging is preformed to evaluate the expression of β3 integrin, which maybe have relationship with myocardial cell apoptosis or apoptotic factors. Myocardial cell apoptosis is detected by 18F-ML-8 PET imaging, which may be applied to a new technology of noninvasive apoptosis imaging in clinal. To explore a new strategy for the treatment of myocardial cell apoptosis, animals are treated with integrin β3 and compared with N-aeetyleysteine treatment. In this study, we evaluate the precise mechanism and molecule targeted therapy of myocardial cell apoptosis using the novel molecular tracer, which provide experimental basis for the imaging diagnosis and molecular treatment of myocardial cell apoptosis in clinic.

心肌细胞凋亡的调控机制、影像诊断、治疗策略及评价，是临床亟待解决的难题。本课题是在前期心肌细胞凋亡分子显像研究的基础上，以调节心肌细胞生长的整合素β3为靶点，合成新颖分子显像剂，利用PET显像技术，从细胞、组织、动物水平深入研究心肌细胞凋亡的调控机制和治疗靶点。构建整合素β3基因过表达和沉默的H9C2心肌细胞，观察缺氧时整合素β3对H9C2细胞凋亡及因子的影响；通过复制心梗模型，18F-AlF-NOTA-PEG3-β-Glu-RGD2 PET显像评价整合素β3受体与心肌细胞凋亡及其因子的关系，18F-ML-8 PET显像评价心肌细胞凋亡，建立无创心肌细胞凋亡显像新技术；用整合素β3治疗心衰动物，并与N-乙酰半胱氨酸抗凋亡效果比较，探索治疗心肌细胞凋亡的新策略。本课题采用新颖分子示踪技术评价心肌细胞凋亡的精准机制及靶向治疗，为心肌细胞凋亡的影像诊断和分子治疗的临床应用提供实验依据。

整合素β3在缺氧诱导的心肌细胞凋亡中起着重要作用，可能成为分子显像和治疗靶点。本研究结果提示整合素β3对缺氧诱导的心肌细胞凋亡具有保护作用，其调节机制与PTEN/Akt/mTOR和ERK1/2信号传导路径相关。在低氧诱导H9C2细胞和原代大鼠心肌细胞凋亡中整合素β3表达增加，伴有HIF1α的表达水平显著升高。急性和慢性心肌梗死后衰竭心肌组织中整合素β3表达增加。shRNA抑制整合素β3会增加了缺氧诱导的心肌细胞凋亡，整合素β3的过度表达减弱了缺氧诱导的心肌细胞凋亡，促进了心肌细胞的增殖。课题组以整合素αvβ3受体为靶点，设计合成新型显像剂[18F]-AlF-NOTA-PEG3-β-Glu-RGD2和凋亡显像剂[18F]AlF-NOTA-PEG3-Cinnamycin，用于心梗后大鼠心肌PET显像。两种显像剂均无生物毒性，具有高稳定性和特异性，主要在肝肾代谢，具有良好的药代动力学特征，适合做心肌显像剂。与心肌组织中各时间点凋亡检测结果一致，[18F]AlF-NOTA-PEG3-Cinnamycin凋亡显像在心梗后第1天和第3天明显，在第7天和第28天几乎不显像。在心梗后第3天，N乙酰半胱氨酸治疗组[18F]AlF-NOTA-PEG3-Cinnamycin摄取较心梗组明显减少。[18F]-AlF-NOTA-PEG3-β-Glu-RGD2显像在心梗后第7天明显，持续至28天，乙酰半胱氨酸（NAC）治疗后摄取明显增加，与组织中αvβ3受体表达一致。两种显像剂在评价心梗后心肌凋亡和修复过程，优于FDG心肌显像技术。本课题以整合素β3为靶点，采用分子机制与分子示踪结合，建立PET心肌细胞凋亡显像新技术，具有良好的临床应用前景。