Karlas Angelos, Nunes Antonio, Driessen Wouter, Liapis Evangelos, Reber Josefine
Chair of Biological Imaging, School of Medicine, Technical University of Munich, 81675 Munich, Germany.
Institute of Biological and Medical Imaging, Helmholtz Zentrum München (GmbH), 85764 Neuherberg, Germany.
Biomedicines. 2021 Nov 16;9(11):1696. doi: 10.3390/biomedicines9111696.
Breast cancer is a complex tumor type involving many biological processes. Most chemotherapeutic agents exert their antitumoral effects by rapid induction of apoptosis. Another main feature of breast cancer is hypoxia, which may drive malignant progression and confer resistance to various forms of therapy. Thus, multi-aspect imaging of both tumor apoptosis and oxygenation in vivo would be of enormous value for the effective evaluation of therapy response. Herein, we demonstrate the capability of a hybrid imaging modality known as multispectral optoacoustic tomography (MSOT) to provide high-resolution, simultaneous imaging of tumor apoptosis and oxygenation, based on both the exogenous contrast of an apoptosis-targeting dye and the endogenous contrast of hemoglobin. MSOT imaging was applied on mice bearing orthotopic 4T1 breast tumors before and following treatment with doxorubicin. Apoptosis was monitored over time by imaging the distribution of xPLORE-APOFL750©, a highly sensitive poly-caspase binding apoptotic probe, within the tumors. Oxygenation was monitored by tracking the distribution of oxy- and deoxygenated hemoglobin within the same tumor areas. Doxorubicin treatment induced an increase in apoptosis-depending optoacoustic signal of xPLORE-APOFL750© at 24 h after treatment. Furthermore, our results showed spatial correspondence between xPLORE-APO750© and deoxygenated hemoglobin. In vivo apoptotic status of the tumor tissue was independently verified by ex vivo fluorescence analysis. Overall, our results provide a rationale for the use of MSOT as an effective tool for simultaneously investigating various aspects of tumor pathophysiology and potential effects of therapeutic regimes based on both endogenous and exogenous molecular contrasts.
乳腺癌是一种涉及多种生物学过程的复杂肿瘤类型。大多数化疗药物通过快速诱导细胞凋亡发挥其抗肿瘤作用。乳腺癌的另一个主要特征是缺氧，这可能会推动恶性进展并导致对各种治疗形式产生抗性。因此，对肿瘤细胞凋亡和体内氧合进行多方面成像对于有效评估治疗反应具有巨大价值。在此，我们展示了一种称为多光谱光声断层扫描（MSOT）的混合成像模式的能力，它能够基于靶向细胞凋亡染料的外源性对比和血红蛋白的内源性对比，提供肿瘤细胞凋亡和氧合的高分辨率同步成像。将MSOT成像应用于携带原位4T1乳腺肿瘤的小鼠，在给予阿霉素治疗之前和之后进行。通过对肿瘤内一种高度敏感的多半胱天冬酶结合凋亡探针xPLORE - APOFL750©的分布进行成像，随时间监测细胞凋亡情况。通过追踪同一肿瘤区域内氧合血红蛋白和脱氧血红蛋白的分布来监测氧合情况。阿霉素治疗在治疗后24小时诱导了xPLORE - APOFL750©依赖于细胞凋亡的光声信号增加。此外，我们的结果显示xPLORE - APO750©与脱氧血红蛋白之间存在空间对应关系。通过离体荧光分析独立验证了肿瘤组织的体内凋亡状态。总体而言，我们的结果为使用MSOT作为一种有效工具提供了理论依据，该工具可基于内源性和外源性分子对比同时研究肿瘤病理生理学的各个方面以及治疗方案的潜在效果。
