Institute of Imaging Science, Vanderbilt University, Nashville, TN, 37232, USA.
Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, 37232, USA.
Sci Rep. 2019 Jul 2;9(1):9540. doi: 10.1038/s41598-019-45864-y.
Imaging apoptosis could provide an early and specific means to monitor tumor responses to treatment. To date, despite numerous attempts to develop molecular imaging approaches, there is still no widely-accepted and reliable method for in vivo imaging of apoptosis. We hypothesized that the distinct cellular morphologic changes associated with treatment-induced apoptosis, such as cell shrinkage, cytoplasm condensation, and DNA fragmentation, can be detected by temporal diffusion spectroscopy imaging (TDSI). Cetuximab-induced apoptosis was assessed in vitro and in vivo with cetuximab-sensitive (DiFi) and insensitive (HCT-116) human colorectal cancer cell lines by TDSI. TDSI findings were complemented by flow cytometry and immunohistochemistry. Cell cycle analysis and flow cytometry detected apoptotic cell shrinkage in cetuximab-treated DiFi cells, and significant apoptosis was confirmed by histology. TDSI-derived parameters quantified key morphological changes including cell size decreases during apoptosis in responsive tumors that occurred earlier than gross tumor volume regression. TDSI provides a unique measurement of apoptosis by identifying cellular characteristics, particularly cell shrinkage. The method will assist in understanding the underlying biology of solid tumors and predict tumor response to therapies. TDSI is free of any exogenous agent or radiation, and hence is very suitable to be incorporated into clinical applications.
成像细胞凋亡可以提供一种早期且特异的手段来监测肿瘤对治疗的反应。尽管目前已经尝试了多种方法来开发分子影像学方法，但仍然没有广泛接受和可靠的方法来进行体内细胞凋亡的成像。我们假设，与治疗诱导的细胞凋亡相关的独特的细胞形态学变化，如细胞收缩、细胞质浓缩和 DNA 片段化，可以通过时间分辨扩散光谱成像（TDSI）来检测。我们通过 TDSI 评估了西妥昔单抗诱导的体外和体内敏感（DiFi）和不敏感（HCT-116）人结肠癌细胞系的细胞凋亡。通过流式细胞术和免疫组织化学对 TDSI 结果进行了补充。细胞周期分析和流式细胞术检测到西妥昔单抗处理的 DiFi 细胞中的凋亡性细胞收缩，组织学证实了明显的凋亡。TDSI 衍生的参数定量了关键的形态变化，包括在响应肿瘤中凋亡期间的细胞大小减小，比肿瘤体积的宏观消退更早发生。TDSI 通过识别细胞特征，特别是细胞收缩，提供了一种独特的细胞凋亡测量方法。该方法将有助于了解实体瘤的潜在生物学，并预测肿瘤对治疗的反应。TDSI 不使用任何外源性试剂或辐射，因此非常适合纳入临床应用。
