Phosphorescence Monitoring of Hypoxic Microenvironment in Solid-Tumors to Evaluate Chemotherapeutic Effects Using the Hypoxia-Sensitive Iridium (III) Coordination Compound

ObjectivesTo utilize phosphorescence to monitor hypoxic microenvironment in solid-tumors and investigate cancer chemotherapeutic effects in vivo.MethodsA hypoxia-sensitive probe named BTP was used to monitor hypoxic microenvironment in solid-tumors. The low-dose metronomic treatment with cisplatin was used in anti-angiogenetic chemotherapeutic programs. The phosphorescence properties of BTP were detected by a spectrofluorometer. BTP cytotoxicity utilized cell necrosis and apoptosis, which were evaluated by trypan blue dye exclusion and Hoechst33342 plus propidium iodide assays. Tumor-bearing mouse models of colon adenocarcinoma were used for tumor imaging in vivo. Monitoring of the hypoxic microenvironment in tumors was performed with a Maestro 2 fluorescence imaging system. Tumor tissues in each group were harvested regularly and treated with pathological hematoxylin and eosin and immunohistochemical staining to confirm imaging results.ResultsBTP did not feature obvious cytotoxicity for cells, and tumor growth in low-dose metronomic cisplatin treated mice was significantly inhibited by chemotherapy. Hypoxic levels significantly increased due to cisplatin, as proven by the expression level of related proteins. Phosphorescence intensity in the tumors of mice in the cisplatin group was stronger and showed higher contrast than that in tumors of saline treated mice.ConclusionsWe develop a useful phosphorescence method to evaluate the chemotherapeutic effects of cisplatin. The proposed method shows potential as a phosphorescence imaging approach for evaluating chemotherapeutic effects in vivo, especially anti-angiogenesis.

研究目的：利用磷光效应监测实体瘤内的缺氧微环境，并在体内探究癌症的化疗效果。研究方法：采用一种名为BTP的缺氧敏感性探针（hypoxia-sensitive probe）监测实体瘤内的缺氧微环境；顺铂低剂量节律化疗方案用于抗血管生成化疗程序。通过荧光分光光度计检测BTP的磷光特性。采用台盼蓝拒染法、Hoechst33342联合碘化丙啶（propidium iodide）染色实验评估BTP诱导的细胞坏死与凋亡，以检测其细胞毒性。构建结肠腺癌荷瘤小鼠模型用于体内肿瘤成像；采用Maestro 2荧光成像系统监测肿瘤内的缺氧微环境。定期采集各组肿瘤组织，进行苏木精-伊红（hematoxylin and eosin）染色与免疫组化染色以验证成像结果。研究结果：BTP对细胞无明显细胞毒性；顺铂低剂量节律化疗可显著抑制小鼠的肿瘤生长。顺铂处理可使肿瘤缺氧水平显著升高，相关蛋白表达水平可证实这一点。顺铂组小鼠肿瘤内的磷光强度较生理盐水处理组更强，且对比度更高。研究结论：本研究开发了一种实用的磷光检测方法，可用于评估顺铂的化疗效果。该方法作为磷光成像手段，在体内化疗效果（尤其是抗血管生成治疗效果）评估方面具有应用潜力。