放射性核素光学成像及黑色素瘤的分子影像学研究

发布时间：2018-07-11 21:43

本文选题：分子影像学 + 放射性核素光学成像　；参考：《中国协和医科大学》2010年博士论文

【摘要】： 分子影像学是一门新兴的交叉学科,涉及到影像学、分子材料学(包括纳米材料)、分子生物学(包括信号传导通路、受体、抗体、配体等)、基因研究等。目前已有多种影像学技术应用于分子影像学研究,如放射性核素成像(nuclear imaging),光学成像(optical imaging,OI),超声成像(ultrosonic imaging)和核磁共振成像(Magnetic resonance imaging, MRI)等。放射性核素成像手段主要包括正电子发射计算机断层成像(position emission tomography, PET)和单光子发射计算机断层成像(single photon emission computed tomography, SPECT)。放射性核素成像首先将放射性药物引入患者体内,在体外检测放射性药物发射出的高能量高穿透性的伽玛射线,从而研究药物在体内的分布。通过与高分辨率的计算机断层扫描技术(X-ray computed tomography)相结合,PET或SPECT可以在显示深部组织的分子影像学特征的同时,高分辨率地显示组织的解剖结构,目前已广泛地应用于临床。光学成像主要包括生物发光成像(bioluminescent imaging)、荧光成像(fluorescence imaging)等,应用于分子及细胞生物学研究和活体(in vivo)表面成像。由于目前通过美国食品药品管理局(Food and Drug Admistraton, FDA)认证的光学探针只有吲哚菁绿(indocyanine green, ICG),光学成像在临床应用较少。多数活体光学成像只初步用于小动物的实验成像。光学成像相比放射性核素成像价格较低廉,且允许具有不同光谱特征的探针进行多通道成像。本文在国际上率先综合了核医学示踪剂和光学成像系统。使用光学系统的高敏感CCD相机检测放射性探针以韧致辐射(Bremsstrahlung radiation)或契伦科夫辐射(Cerenkov radiation)产生的低能量光子,证明了核医学探针应用于光学成像的可行性,拓展了光学成像在临床的应用前景,并为直接监测钇-90 (yttrium-90,90Y)等目前难以监测的放射性治疗用核素提供了有效手段。一般而言,多聚肽比单体拥有更好的受体亲和力和活性。本研究以多聚黑色素细胞刺激激素(a-Melanocyte-Stimulating Hormone,简称a-MSH)类似肽和黑色素瘤为模型,利用正电子发射计算机断层扫描技术(Positron emission tomography,简称PET),对多聚肽的受体亲和力和体内肿瘤靶向能力进行了系统的比较研究。用多肽固相合成法合成了MSH类似肽单体(MSH1),二聚体(MSH2)和四聚体(MSH4),并分别与金属螯合剂DOTA联接(DOTA-MSH1, DOTA-MSH2, DOTA-MSH4)。通过B16/F10鼠黑色素瘤细胞测定三种多肽及联接DOTA后的半数抑制浓度(IC50),评价其受体亲和力。标记64Cu后,进行PET扫描成像,观察其体内分布和肿瘤显像效果。并在不同时间点处死小鼠,取血、肿瘤及各主要器官,测量其每克组织注射百分剂量率(%ID/g)。多肽的各步反应均使用反相高效液相色谱法(RP-HPLC)进行纯化并利用电喷雾质谱(ESI-MS)进行鉴定。DOTA-MSH4在体外实验中具有最高的受体亲和力[IC50=1.00nM(95%可信区间0.83-1.21nM)],但在体内实验中肿瘤摄取量最低(1小时=0.6l±0.02%ID/g；2小时=1.82±0.85%ID/g；4小时=2.98±0.24%ID/g),且在肾脏大量蓄积(1小时=12.91±1.86%ID/g；2小时=20.89±3.98%ID/g；4小时=24.98±2.17%ID/g)。相比之下,DOTA-MSH2有着中等的受体亲和力[IC50=2.06nM(95%可信区间1.48-2.88nM)],却有更高的肿瘤摄取量(1小时=5.65±1.13%ID/g；2小时=5.23±0.5%ID/g 0；4小时=5.39±0.84%ID/g),且在肾脏中的蓄积少于DOTA-MSH4(1小时=18.23±2.50%ID/g；2小时=16.84±3.57%ID/g；4小时=16.44±1.66%ID/g). DOTA-MSH1受体亲和力最低[IC50=3.10nM(95%可信区间2.34-4.10nM)],有着中等的肿瘤摄取量(1小时=2.81+1.49%ID/g；2小时=3.74±1.57%ID/g；4小时=4.20±0.69%ID/g)和较低的肾脏蓄积(1小时=11.79±4.54%ID/g；2小时=11.24±3.95%ID/g；4小时=9.90±1.25%ID/g)。最后,对DOTA-MSH2进行的体内竞争抑制实验显示其具有良好的肿瘤特异性。高受体亲和力的DOTA-MSH4却有着较差的显像效果。在本实验测试的三种多肽探针中,DOTA-MSH2被证明是最佳的黑色素瘤PET显像剂。
[Abstract]:Molecular imaging is a new interdisciplinary subject involving imaging, molecular materials (including nanomaterials), molecular biology (including signal transduction pathways, receptors, antibodies, ligands, etc.), and gene studies. A variety of imaging techniques have been applied to molecular imaging studies, such as radionuclide imaging (nuclear imaging), Guang Xuecheng Such as (optical imaging, OI), ultrasound imaging (ultrosonic imaging) and nuclear magnetic resonance imaging (Magnetic resonance imaging, MRI), etc.. The radionuclide imaging means mainly include positron emission computed tomography (position emission tomography) and single photon emission computed tomography. Ography, SPECT). Radionuclide imaging first introduces radiopharmaceuticals into the patient and detects high energy and high penetration gamma rays emitted by radiopharmaceuticals in vitro, so as to study the distribution of drugs in the body. By combining with high resolution computed tomography (X-ray computed tomography), PET or SPECT can be used. In order to display the molecular imaging features of the deep tissue and display the anatomical structure of the tissue with high resolution, it is now widely used in clinic. Optical imaging mainly includes bioluminescent imaging, fluorescence imaging, and so on. It is applied to molecular and cellular biology research and living body (in vivo). Surface imaging. Because the optical probes certified by the Food and Drug Admistraton (FDA) are currently only indocyanine green (indocyanine green, ICG), optical imaging is less clinically used. Most of the living optical imaging is primarily used for experimental imaging of small animals. Optical imaging is compared to radionuclide imaging prices. It is cheaper and allows multi-channel imaging with probes with different spectral characteristics.
In this paper, nuclear medicine tracer and optical imaging system are first integrated in the world. Using the high sensitive CCD camera of the optical system to detect the low energy photon produced by the radioactive probe (Bremsstrahlung radiation) or the Cherenkov radiation (Cerenkov radiation), the feasibility of the application of the nuclear medical probe to optical imaging is demonstrated. It has expanded the prospect of clinical application of optical imaging and provides an effective means for the direct monitoring of yttrium -90 (yttrium-90,90Y), which is currently difficult to monitor in radionuclides.
In general, polypeptides have better receptor affinity and activity than monomers. This study uses polypeptides (a-Melanocyte-Stimulating Hormone, a-MSH) similar peptides and melanoma as models, and uses positron emission computed tomography (Positron emission tomography, PET) for polypeptides. The receptor affinity and in vivo tumor targeting ability were systematically compared.
MSH similar peptide monomer (MSH1), two polymer (MSH2) and four polymer (MSH4) were synthesized by the solid-phase peptide synthesis method, and DOTA coupling (DOTA-MSH1, DOTA-MSH2, DOTA-MSH4) with metal chelating agent (DOTA-MSH1, DOTA-MSH2, DOTA-MSH4) respectively. Three kinds of polypeptide and half inhibitory concentration (IC50) after joining DOTA were measured by B16/F10 rat melanoma cells, and the receptor affinity was evaluated. After labeling 64Cu, PET scanning was carried out to observe the distribution of the body and the effect of tumor imaging. The mice were killed at different time points, blood, tumor and the main organs were taken to measure the dose rate (%ID/g) per gram of tissue injection. All the steps of the peptide were purified by Reversed Phase High Performance liquid chromatography (RP-HPLC) and used by electrospray ionization mass spectrometry (ESI-MS). The identification of.DOTA-MSH4 has the highest receptor affinity [IC50=1.00nM (95% confidence interval 0.83-1.21nM) in vitro, but in the body, the tumor uptake is the lowest (1 hours =0.6l + 0.02%ID/g; 2 hours =1.82 + 0.85%ID/g; 4 hours =2.98 + 0.24%ID/g), and in a large amount of kidney accumulation (1 hours =12.91 + 1.86%ID/g; 2 hours =20.89) D/g; 4 hours =24.98 + 2.17%ID/g). In contrast, DOTA-MSH2 has a moderate receptor affinity [IC50=2.06nM (95% confidence interval 1.48-2.88nM)], but has higher tumor uptake (1 hours =5.65 + 1.13%ID/g, 2 hours =5.23 + 0.5%ID/g 0, 4 hour =5.39 0.84%ID/g), and the accumulation in the kidney is less than 1 hours (1 hours). 2 hours =16.84 + 3.57%ID/g; 4 hours =16.44 + 1.66%ID/g). DOTA-MSH1 receptor affinity was lowest [IC50=3.10nM (95% confidence interval 2.34-4.10nM)], with moderate tumor uptake (1 hours =2.81+1.49%ID/g; 2 hours =3.74 + 1.57%ID/g; 4 hour =4.20 0.69%ID/g) and lower kidney accumulation (1 hours + 4); 2 hours. 4 + 3.95%ID/g; 4 hours =9.90 + 1.25%ID/g). Finally, in vivo competition inhibition test on DOTA-MSH2 showed that it had good tumor specificity. DOTA-MSH4 with high receptor affinity had poor imaging effect. In the three peptide probes tested in this experiment, DOTA-MSH2 was proved to be the best melanoma PET imaging agent.
【学位授予单位】：中国协和医科大学
【学位级别】：博士
【学位授予年份】：2010
【分类号】：R739.5

【共引文献】