Assessing Angiogenesis by Near-Infrared Imaging

描述（由申请人提供）本研究的长期目标是开发近红外（NIR）可激发荧光造影剂，其靶向血管生成血管，并使用无害光对抗血管生成治疗进行无创评估。然而，为了成功，造影剂必须提供显著的对比增强。我们假设，RGD 4C和CNGRC肽来源于体内噬菌体展示技术，可用于家庭近红外荧光染料α v β 3整合素和CD 13受体，分别在血管生成肿瘤血管。我们进一步提出，使用多个归巢肽连接到聚合物链的尖端的水溶性树枝状聚合物将显着增加配体的结合亲和力，并增强肿瘤和正常组织之间的对比度。为了验证这些假设，将合成携带荧光染料吲哚菁绿色的星形聚（L-谷氨酸）。RGD-4C和CNGRC肽将位点特异性地偶联到聚合物的末端。缀合方案、聚合物载体和配体将变化以使得能够优化荧光性质、受体结合和NIR检测。为了确定新合成的NIR造影剂在血管生成血管的NIR成像中的效用，将使用频域光子迁移ICCD照相机对携带人肿瘤的裸鼠进行成像，以获得作为时间函数的荧光强度，并获得静脉内注射每种造影剂后肿瘤和正常组织中的药代动力学参数。此外，聚合物造影剂将用In-I 11标记，用于同时进行光学和核成像和比较。将评价造影剂在肿瘤中的空间分布，以确认对血管床的特异性靶向。最后，选定的靶向α v β 3和CD 13受体的NIR造影剂将用于评价抗α v β 3和抗CD 13治疗的治疗反应。将尝试将光学成像的对比增强和药代动力学参数与治疗结果、微血管密度计数以及免疫组织化学研究中测量的肿瘤血管系统中mvg 3和CD 13受体的表达水平相关联。提出的研究将有助于定义NIR造影剂的关键设计特征，以成功地使用NIR对肿瘤血管进行成像。

DESCRIPTION (provided by applicant) The long-term goal of this research is to develop near-infrared (NIR) excitable fluorescent contrast agents that target angiogenic blood vessels and enable noninvasive assessment of antiangiogenic therapy using harmless light. To be successful, however, contrast agents must provide significant contrast enhancement. We hypothesize that the RGD4C and CNGRC peptides derived from in vivo phage-displaying technology can be used to home NIR fluorochromes to alpha v beta 3 integrin and CD13 receptors, respectively, in angiogenic tumor blood vessels. We further propose that use of water-soluble dendritic polymers with multiple homing peptides attached to the tips of polymer chains will significantly increase the ligand's binding affinity and enhance the contrast between tumor and normal tissues. To test these hypotheses, star-shaped poly(L-glutamic acid) carrying fluorochrome indocyanine green will be synthesized. RGD-4C and CNGRC peptides will be coupled to the end of the polymers site-specifically. The conjugation scheme, polymeric carriers, and ligands will be varied to enable optimization of fluorescent properties, receptor binding, and NIR detection. To establish the utility of newly synthesized NIR contrast agents in the NIR imaging of angiogenic blood vessels, nude mice bearing human tumors will be imaged using a frequency-domain photon migration ICCD camera to acquire fluorescent intensity as a function of time and obtain pharmacokinetic parameters in tumor and normal tissues following intravenous injection of each contrast agent. In addition, polymeric contrast agent will be labeled with In-I 11 for simultaneous optical and nuclear imaging and comparison. The spacial distribution of the contrast agents in the tumors will be evaluated to confirm the specific targeting to vascular beds. Finally, selected NIR contrast agents targeted to alphavbeta3 and CD13 receptors will be used to evaluate treatment responses to anti-alphavbeta3 and anti-CD13 therapy. Attempts will be made to correlate contrast enhancement and pharmacokinetic parameters derived from optical imaging with treatment outcome, microvessel density counts, and levels of expression ofmvg3 and CD13 receptors in tumor vasculature measured in immunohistochemical studies. The proposed studies will help define critical design features of NIR contrast agents for successfullv imaging tumor vasculature using NIR.