Department of Biological Regulation, Weizmann Institute of Science, 234 Herzl St, Rehovot 76100, Israel.
Radiology. 2013 Sep;268(3):790-801. doi: 10.1148/radiol.13122053. Epub 2013 Jun 25.
To quantitatively monitor the dynamic perivascular recruitment of ferritin heavy chain (FHC)-overexpressing fibroblasts to ovarian carcinoma xenografts by using R2 mapping and biexponential magnetic resonance (MR) relaxometry.
In vivo studies of female mice were approved by the institutional animal care and use committee. In vitro analysis included MR-based R2 relaxation measurements of monkey kidney cell line (CV1) fibroblasts that overexpress FHC, followed by inductively coupled plasma mass spectrometry to assess cellular iron content. For in vivo analysis, CV1-FHC fibroblasts were either mixed with fluorescent human ovarian carcinoma cells before subcutaneous implantation (coinjection) or injected intraperitoneally 4 days after the cancer cells were injected (remote recruitment). Dynamic changes in tumor R2 were used to derive CV1-FHC cell fraction in both models. In coinjection tumors, dynamic contrast material-enhanced MR imaging was used to measure tumor fractional blood volume. Whole-body fluorescence imaging and immunohistochemical staining were performed to validate MR results. One-way repeated measures analysis of variance was used to assess MR and fluorescence imaging results and tumor volume, and one-way analysis of variance was used to assess spectrometric results, fractional blood volume, and immunohistochemical evaluation.
CV1-FHC fibroblasts (vs CV1 fibroblasts) showed enhanced iron uptake (1.8 mmol ± 0.5 × 10(-8) vs 0.9 mmol ± 0.5 × 10(-8); P < .05), retention (1.6 mmol ± 0.5 × 10(-8) vs 0.5 mmol ± 0.5 × 10(-8), P < .05), and cell density-dependent R2 contrast. R2 mapping in vivo revealed preferential recruitment of CV1-FHC cells to the tumor rim in both models. Measurement of fractional blood volume was similar in all tumors (2.6 AU ± 0.5 × 10(-3) for CV1, 2.3 AU ± 0.3 × 10(-3) for CV1-FHC, 2.9 ± 0.3 × 10(-3) for CV1-FHC-ferric citrate). Dynamic changes in CV1-FHC cell fraction determined at MR relaxometry in both models were confirmed at immunohistochemical analysis.
FHC overexpression, when combined with R2 mapping and MR relaxometry, enabled in vivo detection of the dynamic recruitment of exogenously administered fibroblasts to the vasculature of solid tumors.
通过 R2 映射和双指数磁共振（MR）弛豫测量，定量监测过表达铁蛋白重链（FHC）的成纤维细胞在卵巢癌异种移植瘤中的动态血管周募集。
本研究经机构动物护理和使用委员会批准，进行雌性小鼠的体内研究。体外分析包括对过表达 FHC 的猴肾细胞系（CV1）成纤维细胞进行基于 MR 的 R2 弛豫测量，然后通过电感耦合等离子体质谱法评估细胞内铁含量。对于体内分析，CV1-FHC 成纤维细胞在皮下植入前与荧光人卵巢癌细胞混合（共注射），或在癌细胞注射后 4 天腹腔内注射（远程募集）。两种模型均使用肿瘤 R2 的动态变化来推导 CV1-FHC 细胞分数。在共注射肿瘤中，使用动态对比增强磁共振成像测量肿瘤的部分血容量。进行全身荧光成像和免疫组织化学染色以验证 MR 结果。采用单向重复测量方差分析评估 MR 和荧光成像结果以及肿瘤体积，采用单向方差分析评估光谱结果、部分血容量和免疫组织化学评估。
与 CV1 成纤维细胞相比，CV1-FHC 成纤维细胞（vs CV1 成纤维细胞）显示出增强的铁摄取（1.8mmol±0.5×10（-8）vs 0.9mmol±0.5×10（-8）；P<.05）、保留（1.6mmol±0.5×10（-8）vs 0.5mmol±0.5×10（-8）；P<.05）和细胞密度依赖性 R2 对比。体内 R2 映射显示，在两种模型中，CV1-FHC 细胞均优先募集到肿瘤边缘。所有肿瘤的部分血容量测量结果相似（CV1 为 2.6AU±0.5×10（-3），CV1-FHC 为 2.3AU±0.3×10（-3），CV1-FHC-柠檬酸铁为 2.9±0.3×10（-3））。两种模型中通过 MR 弛豫测量确定的 CV1-FHC 细胞分数的动态变化在免疫组织化学分析中得到了证实。
当与 R2 映射和 MR 弛豫测量结合使用时，FHC 过表达可在体内检测到外源性给予的成纤维细胞对实体瘤血管的动态募集。
