Utilizing the Multiradionuclide Resolving Power of SPECT and Dual Radiolabeled Single Molecules to Assess Treatment Response of Tumors.
Utilizing the Multiradionuclide Resolving Power of SPECT and Dual Radiolabeled Single Molecules to Assess Treatment Response of Tumors.
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DOI：
10.1007/s11307-015-0842-8
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发表时间：
2015-10
影响因子：
3.1
通讯作者：
Achilefu S
中科院分区：
文献类型：
--
作者：
Xu B;Shokeen M;Sudlow GP;Harpstrite SE;Liang K;Cheney PP;Edwards WB;Sharma V;Laforest R;Akers WJ;Achilefu S
单光子发射计算机断层扫描（SPECT）放射性核素对具有不同的衰减率和不同的能量最大值，可以同时检测双伽马信号和实时评估体内动态功能和分子过程。在这里，我们报告了用两种不同的放射性核素标记的单个分子的功能SPECT成像的图像采集和定量方案。采用模块化固相合成法制备LS370和LS734。每个试剂都有一个caspase-3可切割的报告基序，在分子的另一端有一个酪氨酸残基和一个螯合剂。在人MDA-MB-231乳腺癌细胞中评估细胞摄取和外排。生物分布研究在肿瘤初始和原位4T1转移性乳腺癌肿瘤小鼠中进行。使用含有不同放射性核素浓度的幻影小瓶开发了NanoSPECT双成像验证和衰减校正参数。在MMTV-PyMT转基因小鼠中进行了原理验证的SPECT成像。LS370和LS734分别用125I和111In或99mTc进行单或双放射性标记。细胞检测显示，在2小时内，[125I]LS734的摄取率（3.6±0.5）比[125I]LS370（0.3±0.3）高11倍（P<0.001）。化疗后，[125I]LS734的细胞保留率比未治疗的细胞高3倍（P<0.05）。注射后1 h的药代动力学表明，[125I]LS734的血潴留（%ID/g）比[125I]LS370的（1.6±0.1）更长。在双侧原位4T1肿瘤小鼠中，[125I]LS734和[125I]LS370的摄取（%ID/g）分别为2.4±0.3和1.2±0.03。碘化酪氨酸肽残基标记在体外条件下可稳定达24 h；体内观察到快速全身脱碘（高甲状腺摄取）。使用标准的幻影研究演示了基于不同伽马射线能量的放射性核素信号的反卷积。在MMTV-PyMT小鼠中，双标记[111In] - [125I]LS734成像，伽马信号是可分离和可量化的。图像处理方案的开发，定量信号分离产生的caspase-3响应双放射性标记SPECT探针。在多放射性核素纳米spect成像中实现了串扰解混。体外和体内数据显示了结构-活性关系，用于开发用于比率SPECT成像的功能剂。
Single photon emission computed tomography (SPECT) radionuclide pairs having distinct decay rates and different energy maxima enable simultaneous detection of dual gamma signals and real-time assessment of dynamic functional and molecular processes in vivo. Here, we report image acquisition and quantification protocols for a single molecule labeled with two different radionuclides for functional SPECT imaging. LS370 and LS734 were prepared using modular solid phase peptide synthesis. Each agent has a caspase-3 cleavable reporting motif, flanked by a tyrosine residue and a chelator at the opposite end of molecule. Cell uptake and efflux were assessed in human MDA-MB-231 breast cancer cells. Biodistribution studies were conducted in tumor naive and orthotopic 4T1 metastatic breast cancer tumor mice. NanoSPECT dual-imaging validation and attenuation correction parameters were developed using phantom vials containing varying radionuclide concentrations. Proof-of-principle SPECT imaging was performed in MMTV-PyMT transgenic mice. LS370 and LS734 were singly or dually radiolabeled with 125I and 111In or 99mTc. Cell assays demonstrated 11-fold higher percent uptake (P<0.001) of [125I]LS734 (3.6±0.5) compared to [125I]LS370 (0.3±0.3) at 2 h. Following chemotherapy, cellular retention of [125I]LS734 was 3-fold higher (P<0.05) than untreated cells. Pharmacokinetics at 1 h postinjection demonstrated longer blood retention (%ID/g) for [125I]LS734 (3.2±0.9) compared to [125I]LS370 (1.6±0.1). In mice bearing bilateral orthotopic 4T1 tumors, the uptake (%ID/g) was 2.4±0.3 for [125I]LS734 and 1.2±0.03 for [125I]LS370. The iodinated tyrosine peptide residue label was stable under in vitro conditions for up to 24 h; rapid systemic deiodination (high thyroid uptake) was observed in vivo. Phantom studies using standards demonstrated deconvolution of radionuclide signals based on different gamma ray energies. In MMTV-PyMT mice imaged with dual-labeled [111In]–[125I]LS734, the gamma signals were separable and quantifiable. Image processing protocols were developed for quantitative signal separation resulting from a caspase-3 responsive dual-radiolabeled SPECT probe. Crosstalk unmixing was obtained for multiradionuclide NanoSPECT imaging. In vitro and in vivo data demonstrated structure–activity relationships for developing functional agents for ratiometric SPECT imaging.