Aortic diameter is a standard parameter for defining disease severity of thoracic aortic aneurysms. In mouse studies, aortic diameters can be measured in situ directly, but this approach has a potential confounder of underestimation due to the absence of physiological arterial blood pressure. In the present study, we developed an in situ approach for authentic aortic measurements. Thoracic aortic aneurysms were induced by beta-aminopropionitrile (BAPN, 0.5% wt/vol) administration in 4-week-old male C57BL/6J mice. Ultrasonography was performed to examine aortic dimensions, and mice with thoracic aortic dilatations were terminated subsequently. After saline perfusion through the left ventricle, periaortic tissues were removed to expose thoracic aortas. Optimal cutting temperature (OCT) compound was injected via the left ventricle to maintain aortic patency. In situ aortic images were captured pre- and post-OCT injection. In mice with severe thoracic aortic aneurysms, smaller aortic diameters were observed prior to OCT injection compared to ultrasound measurements, while aortic diameters in situ after OCT were comparable to diameters measured using ultrasound. A telemetry system demonstrated that maximal luminal pressures during 150 ul of OCT injection were 90 mmHg. Immunostaining for CD31 revealed that endothelial cells were preserved in the intima after OCT injection. These results indicate that OCT injection does not cause aortic damages due to excess pressures. In conclusion, in situ imaging with OCT injection provides authentic aortic measurements without overt aortic damage in mice with thoracic aortic aneurysms.

中文翻译：

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小鼠胸主动脉瘤的原位测量验证

主动脉直径是定义胸主动脉瘤疾病严重程度的标准参数。在小鼠研究中，可以直接在原位测量主动脉直径，但是由于缺乏生理动脉血压，这种方法可能会导致低估。在本研究中，我们开发了一种用于真实主动脉测量的原位方法。在4周龄的雄性C57BL / 6J小鼠中，β-氨基丙腈（BAPN，0.5％wt / vol）给药可诱发胸主动脉瘤。进行超声检查以检查主动脉大小，随后终止具有胸主动脉扩张的小鼠。在通过左心室灌注盐水后，去除腹主动脉组织以暴露胸主动脉。通过左心室注射最佳切割温度（OCT）化合物以维持主动脉通畅。在OCT注射之前和之后捕获原位主动脉图像。与超声测量相比，在患有严重胸主动脉瘤的小鼠中，OCT注射之前观察到的主动脉直径较小，而OCT后原位的主动脉直径与超声测量的直径相当。遥测系统表明，在150 ul OCT注射过程中，最大腔内压力为90 mmHg。对CD31的免疫染色显示，OCT注射后内皮细胞保留在内膜中。这些结果表明，OCT注射不会因压力过大而引起主动脉损伤。综上所述，