Department of Endocrinology and Metabolic Diseases, Leiden University Medical Center, Leiden, The Netherlands.
PLoS One. 2012;7(2):e31875. doi: 10.1371/journal.pone.0031875. Epub 2012 Feb 13.
Bioluminescence imaging (BLI) has shown its appeal as a sensitive technique for in vivo whole body optical imaging. However, the development of injectable tumor-specific near-infrared fluorescent (NIRF) probes makes fluorescence imaging (FLI) a promising alternative to BLI in situations where BLI cannot be used or is unwanted (e.g., spontaneous transgenic tumor models, or syngeneic mice to study immune effects).In this study, we addressed the questions whether it is possible to detect tumor progression using FLI with appropriate sensitivity and how FLI correlates with BLI measurements. In addition, we explored the possibility to simultaneously detect multiple tumor characteristics by dual-wavelength FLI (~700 and ~800 nm) in combination with spectral unmixing. Using a luciferase-expressing 4T1-luc2 mouse breast cancer model and combinations of activatable and targeting NIRF probes, we showed that the activatable NIRF probes (ProSense680 and MMPSense680) and the targeting NIRF probes (IRDye 800CW 2-DG and IRDye 800CW EGF) were either activated by or bound to 4T1-luc2 cells. In vivo, we implanted 4T1-luc2 cells orthotopically in nude mice and were able to follow tumor progression longitudinally both by BLI and dual-wavelength FLI. We were able to reveal different probe signals within the tumor, which co-localized with immuno-staining. Moreover, we observed a linear correlation between the internal BLI signals and the FLI signals obtained from the NIRF probes. Finally, we could detect pulmonary metastases both by BLI and FLI and confirmed their presence histologically.Taken together, these data suggest that dual-wavelength FLI is a feasible approach to simultaneously detect different features of one tumor and to follow tumor progression with appropriate specificity and sensitivity. This study may open up new perspectives for the detection of tumors and metastases in various experimental models and could also have clinical applications, such as image-guided surgery.
生物发光成像（BLI）已被证明是一种用于体内全身光学成像的敏感技术。然而，可注射的肿瘤特异性近红外荧光（NIRF）探针的发展使得荧光成像（FLI）成为 BLI 无法使用或不希望使用的情况下（例如，自发转基因肿瘤模型或用于研究免疫效应的同基因小鼠）的有前途的替代方法。在这项研究中，我们提出了以下问题：是否可以使用适当灵敏度的 FLI 检测肿瘤进展，以及 FLI 如何与 BLI 测量相关。此外，我们还探索了通过双波长 FLI（700 和800nm）结合光谱解混来同时检测多个肿瘤特征的可能性。我们使用表达荧光素酶的 4T1-luc2 小鼠乳腺癌模型和激活型和靶向 NIRF 探针的组合，表明激活型 NIRF 探针（ProSense680 和 MMPSense680）和靶向 NIRF 探针（IRDye 800CW 2-DG 和 IRDye 800CW EGF）被 4T1-luc2 细胞激活或结合。在体内，我们将 4T1-luc2 细胞原位植入裸鼠中，并能够通过 BLI 和双波长 FLI 进行纵向肿瘤进展。我们能够揭示肿瘤内的不同探针信号，这些信号与免疫染色共定位。此外，我们观察到内部 BLI 信号与从 NIRF 探针获得的 FLI 信号之间存在线性相关性。最后，我们能够通过 BLI 和 FLI 检测肺转移，并通过组织学证实其存在。总之，这些数据表明，双波长 FLI 是一种可行的方法，可以同时检测一个肿瘤的不同特征，并以适当的特异性和灵敏度跟踪肿瘤进展。这项研究可能为各种实验模型中的肿瘤和转移的检测开辟新的视角，并且也可能具有临床应用，例如图像引导手术。
