Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology, ETH Zurich, Wolfgang-Pauli-Str. 10, HCI H303, 8093 Zurich, Switzerland.
Angiogenesis. 2013 Jul;16(3):525-40. doi: 10.1007/s10456-013-9332-2. Epub 2013 Jan 17.
Preclinical vascular research has been hindered by a lack of methods that can sensitively image and quantify vascular perfusion and leakage in vivo. In this study, we have developed dynamic near-infrared imaging methods to repeatedly visualize and quantify vascular leakage in mouse skin in vivo, and we have applied these methods to transgenic mice with overexpression of vascular endothelial growth factors VEGF-A or -C. Near-infrared dye conjugates were developed to identify a suitable vascular tracer that had a prolonged circulation lifetime and slow leakage into normal tissue after intravenous injection. Dynamic simultaneous imaging of ear skin and a large blood vessel in the leg enabled determination of the intravascular signal (blood volume fraction) from the tissue signal shortly after injection and quantifications of vascular leakage into the extravascular tissue over time. This method allowed for the sensitive detection of increased blood vascularity and leakage rates in K14-VEGF-A transgenic mice and also reliably measured inflammation-induced changes of vascularity and leakage over time in the same mice. Measurements after injection of recombinant VEGF-A surprisingly revealed increased blood vascular leakage and lymphatic clearance in K14-VEGF-C transgenic mice which have an expanded cutaneous lymphatic vessel network, potentially indicating unanticipated effects of lymphatic drainage on vascular leakage. Increased vascular leakage was also detected in subcutaneous tumors, confirming that the method can also be applied to deeper tissues. This new imaging method might facilitate longitudinal investigations of the in vivo effects of drug candidates, including angiogenesis inhibitors, in preclinical disease models.
临床前血管研究受到缺乏能够敏感地成像和定量体内血管灌注和渗漏的方法的阻碍。在这项研究中，我们开发了动态近红外成像方法，可反复可视化和定量体内小鼠皮肤的血管渗漏，并将这些方法应用于血管内皮生长因子 VEGF-A 或 -C 过表达的转基因小鼠。开发了近红外染料缀合物来鉴定合适的血管示踪剂，该示踪剂具有延长的循环寿命，并且在静脉注射后缓慢渗漏到正常组织中。耳皮肤和腿部大血管的动态同步成像可在注射后不久从组织信号中确定血管内信号（血容量分数），并随时间定量测量血管外组织中的血管渗漏。该方法能够灵敏地检测 K14-VEGF-A 转基因小鼠中增加的血管生成和渗漏率，并且还能够可靠地测量同一小鼠中随时间推移的炎症引起的血管生成和渗漏变化。出乎意料的是，在 K14-VEGF-C 转基因小鼠（其具有扩展的皮肤淋巴管网络）中，注射重组 VEGF-A 后可检测到增加的血管渗漏和淋巴清除，这可能表明淋巴引流对血管渗漏的意外影响。在皮下肿瘤中也检测到血管通透性增加，证实该方法也可应用于更深层的组织。这种新的成像方法可能有助于在临床前疾病模型中对候选药物（包括血管生成抑制剂）的体内作用进行纵向研究。
