使用基于双峰α2-抗纤溶酶的造影剂对早期血栓形成进行分子磁共振成像。

Molecular MRI of early thrombus formation using a bimodal alpha2-antiplasmin-based contrast agent.

作者信息

Miserus Robbert-Jan J H M, Herías M Veronica, Prinzen Lenneke, Lobbes Marc B I, Van Suylen Robert-Jan, Dirksen Anouk, Hackeng Tilman M, Heemskerk Johan W M, van Engelshoven Jos M A, Daemen Mat J A P, van Zandvoort Marc A M J, Heeneman Sylvia, Kooi Marianne Eline

机构信息

Department of Radiology, Maastricht University Medical Centre, Maastricht, the Netherlands.

出版信息

JACC Cardiovasc Imaging. 2009 Aug;2(8):987-96. doi: 10.1016/j.jcmg.2009.03.015.

DOI:10.1016/j.jcmg.2009.03.015

PMID:19679287

Abstract

OBJECTIVES

We aimed to investigate whether early thrombus formation can be visualized with in vivo magnetic resonance imaging (MRI) by the use of a novel bimodal alpha(2)-antiplasmin-based contrast agent (CA).

BACKGROUND

Thrombus formation plays a central role in several vascular diseases. During the early phases of thrombus formation, activated factor XIII (FXIIIa) covalently cross-links alpha(2)-antiplasmin to fibrin, indicating the potential of alpha(2)-antiplasmin-based CAs in the detection of early thrombus formation.

METHODS

A bimodal CA was synthesized by coupling gadolinium-diethylene triamine pentaacetic acid and rhodamine to an alpha(2)-antiplasmin-based peptide. For the control CA, a glutamine residue essential for cross-linking was replaced by alanine. In vitro-generated thrombi were exposed to both CAs and imaged by MRI and 2-photon laser-scanning microscopy. Immunohistochemistry was performed on human pulmonary thromboemboli sections to determine the presence of alpha(2)-antiplasmin and FXIII in different thrombus remodeling phases. In vivo feasibility of the CA in detecting early thrombus formation specifically was investigated with MRI.

RESULTS

In vitro-generated thrombi exposed to the alpha(2)-antiplasmin-based CA showed hyperintense magnetic resonance signal intensities at the thrombus edge. No hyperintense signal was observed when we used the alpha(2)-antiplasmin-based CA in the presence of FXIII inhibitor dansylcadaverine nor when we used the control CA. Two-photon laser-scanning microscopy demonstrated that the alpha(2)-antiplasmin-based CA bound to fibrin. Immunohistochemistry demonstrated substantial alpha(2)-antiplasmin staining in fresh compared with lytic and organized thrombi. The administration of CA in vivo within seconds after inducing thrombus formation increased contrast-to-noise ratios (CNRs 2.28 +/- 0.39, n=6) at the site of thrombus formation compared with the control CA (CNRs -0.14 +/- 0.55, p = 0.003, n = 6) and alpha(2)-antiplasmin-based CA administration 24 to 48 h after thrombus formation (CNRs 0.11 +/- 0.23, p = 0.006, n = 6).

CONCLUSIONS

A bimodal CA was developed, characterized, and validated. Our results showed that this bimodal CA enabled noninvasive in vivo magnetic resonance visualization of early thrombus formation.

摘要

目的

我们旨在研究通过使用一种新型的基于α2 - 抗纤溶酶的双模态造影剂（CA），能否利用体内磁共振成像（MRI）观察到早期血栓形成。

背景

血栓形成在多种血管疾病中起核心作用。在血栓形成的早期阶段，活化的因子 XIII（FXIIIa）将α2 - 抗纤溶酶与纤维蛋白共价交联，这表明基于α2 - 抗纤溶酶的造影剂在检测早期血栓形成方面具有潜力。

方法

通过将钆 - 二乙烯三胺五乙酸和罗丹明偶联到基于α2 - 抗纤溶酶的肽上合成双模态造影剂。对于对照造影剂，将交联所必需的谷氨酰胺残基替换为丙氨酸。将体外生成的血栓暴露于两种造影剂中，并通过MRI和双光子激光扫描显微镜成像。对人肺血栓栓塞切片进行免疫组织化学分析，以确定不同血栓重塑阶段α2 - 抗纤溶酶和FXIII的存在情况。利用MRI研究造影剂在体内特异性检测早期血栓形成的可行性。

结果

暴露于基于α2 - 抗纤溶酶的造影剂的体外生成血栓在血栓边缘显示出高强度磁共振信号强度。当在FXIII抑制剂丹磺酰尸胺存在下使用基于α2 - 抗纤溶酶的造影剂时，以及使用对照造影剂时，均未观察到高强度信号。双光子激光扫描显微镜显示基于α2 - 抗纤溶酶的造影剂与纤维蛋白结合。免疫组织化学显示，与溶解和机化血栓相比，新鲜血栓中有大量α2 - 抗纤溶酶染色。在诱导血栓形成后数秒内体内注射造影剂，与对照造影剂（对比噪声比 -0.14 ± 0.55，p = 0.003，n = 6）和血栓形成后24至48小时注射基于α2 - 抗纤溶酶的造影剂（对比噪声比0.11 ± 0.23，p = 0.006，n = 6）相比，血栓形成部位的对比噪声比（CNRs 2.28 ± 0.39，n = 6）增加。