Jaffer Farouc A, Tung Ching-Hsuan, Wykrzykowska Joanna J, Ho Nan-Hui, Houng Aiilyan K, Reed Guy L, Weissleder Ralph
Center for Molecular Imaging Research, Massachusetts General Hospital, Harvard Medical School, Charlestown, USA.
Circulation. 2004 Jul 13;110(2):170-6. doi: 10.1161/01.CIR.0000134484.11052.44. Epub 2004 Jun 21.
Activated factor XIII (FXIIIa) mediates fibrinolytic resistance and is a hallmark of newly formed thrombi. In vivo imaging of FXIIIa activity could further elucidate the role of this molecule in thrombosis and other biological processes and aid in the clinical detection of acute thrombi.
An FXIIIa-sensitive near-infrared fluorescence imaging agent (A15) was engineered by conjugating a near-infrared fluorochrome to a peptide ligand derived from the amino terminus of alpha2-antiplasmin. To evaluate the molecular specificity of A15 for FXIIIa, a control agent (C15) was also synthesized by modifying a single key glutamine residue in A15. Fluorescence imaging experiments with A15 demonstrated stronger thrombosis enhancement in human plasma clots in vitro (P<0.001 versus C15 clots and other controls). A15 was found to be highly specific for the active site of FXIIIa and was covalently bound to fibrin. In vivo murine experiments with A15 demonstrated significant signal enhancement in acute intravascular thrombi (P<0.05 versus C15 group). Minimal A15 enhancement was seen in older aged thrombi (>24 hours), consistent with an expected decline of FXIIIa activity over time. Imaging results were confirmed on correlative histopathology and fluorescence microscopy.
A15 is a novel optical imaging agent that is specifically crosslinked to fibrin by FXIIIa, permitting detection of FXIIIa activity in experimental thrombi in vivo. This agent should permit assessment of FXIIIa activity in a broad range of biological processes and could aid in the clinical diagnosis of acute thrombi.
活化的因子 XIII（FXIIIa）介导纤维蛋白溶解抵抗，是新形成血栓的一个标志。FXIIIa 活性的体内成像可进一步阐明该分子在血栓形成和其他生物学过程中的作用，并有助于急性血栓的临床检测。
通过将近红外荧光染料与源自α2-抗纤溶酶氨基末端的肽配体偶联，设计了一种对 FXIIIa 敏感的近红外荧光成像剂（A15）。为了评估 A15 对 FXIIIa 的分子特异性，还通过修饰 A15 中的一个关键谷氨酰胺残基合成了一种对照剂（C15）。用 A15 进行的荧光成像实验表明，在体外人血浆凝块中血栓形成增强更明显（与 C15 凝块和其他对照相比，P<0.001）。发现 A15 对 FXIIIa 的活性位点具有高度特异性，并与纤维蛋白共价结合。用 A15 进行的体内小鼠实验表明，急性血管内血栓中有明显的信号增强（与 C15 组相比，P<0.05）。在较老的血栓（>24 小时）中 A15 的增强最小，这与 FXIIIa 活性随时间预期下降一致。成像结果在相关组织病理学和荧光显微镜检查中得到证实。
A15 是一种新型光学成像剂，可通过 FXIIIa 与纤维蛋白特异性交联，从而在体内实验性血栓中检测 FXIIIa 的活性。该试剂应能在广泛的生物学过程中评估 FXIIIa 的活性，并有助于急性血栓的临床诊断。
