荧光蛋白活体成像系统在肿瘤研究中的应用

活体动物体内光学成像作为一项新兴的分子、基因表达的分析检测技术,已成功应用于生命科学、生物医学、分子生物学和药物研发等领域。荧光技术介导的活体动物光学成像在活体肿瘤研究中的应用已日趋深入,包括应用荧光蛋白对肿瘤内环境、肿瘤转移过程、休眠肿瘤细胞以及肿瘤治疗应答成像,本文对这些研究进展作一综述。     

体内生物发光成像在肿瘤转移研究中的应用

体内生物发光成像（in vivo bioluminescence imaging）在生物医学研究中是一个强有力的工具，能够非侵入性、定量及实时动态监测活体动物体内的生物学过程。一个完整的生物发光成像过程，包括构建荧光素酶（luciferase）报告基因，建立稳定表达荧光素酶的细胞，再将此细胞移植到动物体内，进而可以在体外通过敏感的光学检测系统检测到动物体内特定部位所发出的光。生物发光成像能够示踪特定细胞（肿瘤细胞、免疫细胞、干细胞和细菌等）在体内的迁移，反映特定基因的时空特异性表达以及蛋白质间相互作用等。本文主要就生物发光成像的原理、特点及其在肿瘤转移相关研究中的应用作一概述。     

红色荧光蛋白和荧光素酶双报告基因转基因小鼠的建立

背景与目的:活体动物体内光学成像(optical in vivo imaging)主要采用生物发光与荧光两种技术。生物发光是用荧光素酶(luciferase,Luc)基因标记细胞或DNA,而荧光技术则采用荧光报告基团(GFP、RFP、Cyt及dyes等)进行标记,利用一套非常灵敏的光学检测仪器,能够直接监控活体生物体内的细胞活动和基因行为,生物发光成像具有高的灵敏度和特异性,同时生物发光信号可用于精确定量,而荧光成像具有方便、便宜、直观、标记靶点多样和易于被大多数研究人员接受的优点。本研究基于慢病毒介导的转基因方法制备红色荧光蛋白(red fluorescent protein,RFP)和Luc双报告基因转基因小鼠(即RL转基因小鼠),将这两种技术融为一体。方法:制备携带RFP和Luc基因(简写RL基因)的慢病毒,然后将携带RL基因的慢病毒注入小鼠单细胞受精卵卵周隙以感染受精卵,胚胎移植进假孕母鼠以获得仔鼠,应用小动物活体成像仪、体视荧光显微镜和PCR等在蛋白和DNA水平上筛选和鉴定,并获得RL转基因小鼠。结果:移植卵周隙注射有慢病毒的胚胎125枚给6只假孕母鼠,其中4只假孕母鼠怀孕,共生仔鼠20只;利用小动物活体成像仪检测RFP和Luc表达,在蛋白水平证实20只F0代中,3只高表达RFP和Luc;DNA水平检测证实,3只RFP和Luc阳性的小鼠基因组中确实整合有外源转基因RL,预示基因型鉴定结果很好验证了小动物活体成像仪筛选和鉴定结果。此外,RL转基因首建鼠基因组中整合的RL转基因可稳定遗传至下一代,并能正常表达。RL转基因小鼠主要脏器均可见红色荧光和Luc信号,但不同脏器间荧光和Luc强度有差异。结论:成功制备RL双报告基因转基因小鼠,为后续研究干细胞在肿瘤发生、发展和转移中的作用和造血重构等提供双报告基因标记的各种移植用供体细胞,并对此供体细胞及其在体内衍生的细胞进行灵敏的非损伤、实时可视化体内跟踪。     

绿、红双色荧光蛋白在活体肿瘤细胞成像中的应用

 荧光蛋白成像技术的诞生为细胞生物体内研究提供了新的机遇。该技术已经在很多领域得到广泛应用，其自身也在不断发展。近年来，多色荧光蛋白标记成像技术受到重视，尤其是绿色和红色荧光蛋白，已在很多研究工作中被采用，对该方面的研究进行综述。     

人肺癌裸小鼠模型活体成像的动态观察

目的:建立稳定表达绿色荧光蛋白的人肺癌细胞系,并探讨小动物活体荧光成像系统在肺癌皮下移植瘤模型中的应用.方法:用慢病毒转染的方法建立表达绿色荧光蛋白的人肺癌细胞系NCI-H460-GFP,接种至裸小鼠体内建立皮下移植瘤模型,通过小动物活体成像系统连续5周观察肿瘤在小鼠皮下的动态生长情况.结果:建立了转染率接近100%的人肺癌NCI-H460-GFP细胞系,在体外及裸小鼠体内均能够长期稳定表达绿色荧光蛋白.活体荧光成像观察发现,1～4周随着肿瘤体积逐渐增大,平均荧光光子数逐渐增加;5周时随着肿瘤出现明显坏死,平均荧光光子数呈现下降趋势.结论:稳定表达绿色荧光蛋白的NCI-H460-GFP细胞系及其动物模型可以为肺癌研究提供理想的实验材料,应用小动物活体成像系统能够客观定量评价肿瘤在动物体内的生长情况.     

应用活体内生物发光技术对人高转移大细胞肺癌细胞株L9981成瘤性和转移性研究

背景与目的应用阳离子脂质体介导的基因转染方法对nm23-H1缺失的人高转移大细胞肺癌细胞株L9981进行荧光素酶基因(Luc)标记,建立稳定高效表达荧光素酶(Luciferase)基因的人高转移大细胞肺癌细胞株L9981-Luc。应用活体生物荧光成像技术,非侵入性地连续检测小鼠(裸鼠和SCID鼠)皮下肿瘤模型发展演进、自发转移的过程。方法将带有荧光素酶基因(Luc)的质粒PGL4.17经阳离子脂质体介导转入人高转移大细胞肺癌细胞株L9981中,筛选出高效稳定表达荧光素酶的细胞株。将转染后的细胞接种于裸鼠和SCID鼠右后腿腹股沟皮下,建立皮下肿瘤模型,利用活体内可见光成像系统观察其在小鼠体内的生长和转移过程。结果转基因人高转移大细胞肺癌细胞株L9981-Luc可在体内、外持续稳定表达荧光素酶,细胞数和发光值成直线相关。成功地建立了表达荧光素酶活性的动物肿瘤皮下自发转移模型。L9981-Luc保留了原有的高转移特性。瘤重和发光强度呈直线相关。结论利用活体内生物发光技术可以非侵袭性地连续示踪肿瘤细胞在活体内的生长和转移过程,为研究肺癌侵袭转移过程及其机理和最佳治疗策略的选择提供了新的手段和工具。     

应用生物发光活体成像技术进行抗肿瘤研究进展

摘 要：生物发光活体成像技术是基于荧光素酶报告系统进行小动物组织、细胞和分子体内行为研究的新兴生命科学技术,在抗肿瘤研究领域应用极为广泛。全文概述生物发光活体成像技术的原理、综述了生物发光活体成像在抗肿瘤研究方面应用的最新进展以及发展趋势,为应用该技术进行抗肿瘤领域研究提供参考。     

量子点荧光成像在肿瘤诊治应用研究进展

量子点(quantum dot,QD),又名“人造原子”,是一种用原子人工合成的纳米材料,其在紫外光激发下可发出不同波长的荧光.QD直径小、发出的荧光峰窄、荧光亮度持久,具有取代有机染料用于肿瘤诊治的潜能.总结近年QD在荧光成像及肿瘤诊治方面的研究进展.方法 应用PubMed及中国知网(CNKI)数据库检索系统,以“quantum dots,fluorescence imaging,oncotherapy,tumor therapy,量子点,肿瘤治疗,肿诊断,荧光成像”为关键词,检索2005-01-2016-03的相关文献391篇.纳入标准:(1)可用于生物荧光成像的低毒化QD;(2)靶向识别的功能化QD.根据纳入标准最终分析31篇文献.结果 低毒化QD在细胞成像、活体靶向成像、淋巴结成像、活体肿瘤成像、活体肿瘤细胞示踪等荧光成像方面的研究,使正确定位淋巴结、利用QD深成像能力发现极小的肿瘤、乃至彻底切除肿瘤组织成为可能.功能化QD在肿瘤早期诊断和治疗上发挥更大作用,QD的药物靶向和QD介导的光热治疗肿瘤也有很好的临床应用前景.结论 QD在生物荧光成像及肿瘤诊疗中的潜力巨大,具有进一步探索开发利用于临床的价值.     

EGFP标记的人肺癌裸鼠原位移植模型的建立

背景与目的 小鼠活体分子成像模型可以连续实时监测活体肿瘤的变化.本研究拟通过外科原位移植法建立表达绿色荧光蛋白的肺癌裸鼠原位移植模型并探讨其肿瘤生物学特性,从而建立一个良好的肺癌动物实验研究平台.方法 利用逆转录病毒转染法将增强型绿色荧光蛋白基因导人人肺癌大细胞系NCI-H460,采用外科原位移植法建立肺癌原位移植模型.定期通过小动物活体荧光成像系统观察肿瘤生长,利用相关性检验分析荧光面积和肿瘤体积之间的相关关系,并观察原位移植术后裸鼠的生存期和肿瘤转移情况.结果 模型建立后1周通过皮瓣在荧光体视镜下可观察到肺部肿瘤的绿色荧光,成瘤率为100%.荷瘤裸小鼠平均生存期为34.2天.解剖裸鼠观察到肿瘤侵及对侧肺、纵隔及肺门淋巴结、胸膜和膈肌,转移率分别为87.596、75%、25%和12.5%.肿瘤体积和荧光面积具有相关性(r=0.873,P=0.001).结论 外科原位移植法建立的表达EGFP的裸鼠肺癌原位模型是肺癌临床前研究的理想的实验工具.应用小动物活体荧光成像系统能够定量客观评价肿瘤在动物体内的生长、侵袭和转移,该模型可应用于肺癌的基础研究和新药开发.     

基于分子影像的非小细胞肺癌分子靶向治疗及免疫治疗进展

我国癌症发病率与死亡率中肺癌均高居第一位，其中非小细胞肺癌（NSCLC）占肺癌85%以上， NSCLC传统治疗方式包括手术、化疗、放疗等。近十几年来，NSCLC相关临床治疗取得巨大突破，代表性治疗新方案即为分子靶向治疗和免疫治疗，然而，上述治疗方式成功发挥治疗作用前提和关键则是精准选择NSCLC患者治疗优势人群。分子影像可以在活体状态下，应用影像学方法对人或动物体内细胞和分子水平生物学过程进行成像、定性和定量研究，着眼于生物过程基础变化而不是生物变化最终结果，进而实现精准选择治疗优势人群、分子水平精准监测治疗效果、及时进行预后评估等目的，对分子靶向治疗以及免疫治疗意义重大。该文综述分子影像在NSCLC分子靶向治疗以及免疫治疗中开展的相关研究。     

The evolution of imaging in cancer: current state and future challenges

Molecular imaging allows for the remote, noninvasive sensing and measurement of cellular and molecular processes in living subjects. Drawing upon a variety of modalities, molecular imaging provides a window into the biology of cancer from the subcellular level to the patient undergoing a new, experimental therapy. As signal transduction cascades and protein interaction networks become clarified, an increasing number of relevant targets for cancer therapy--and imaging--become available. Although conventional imaging is already critical to the management of patients with cancer, molecular imaging will provide even more relevant information, such as early detection of changes with therapy, identification of patient-specific cellular and metabolic abnormalities, and the disposition of therapeutic, gene-tagged cells throughout the body--all of which will have a considerable impact on morbidity and mortality. This overview discusses molecular imaging in oncology, providing examples from a variety of modalities, with an emphasis on emerging techniques for translational imaging.     

Magnetic resonance tomography: potentials of molecular imaging

Molecular imaging is "the in-vivo characterization and measurement of biological processes at the cellular and molecular level" and allows the imaging of molecular abnormalities associated with diseases long before morphological changes can be detected. At present, the use of magnetic resonance imaging (MRI) for molecular and cellular imaging is rapidly increasing. MRI is a very attractive candidate, since current MRI protocols already provide anatomic, functional, and biochemical information of excellent image quality and with high spatial resolution. Combining this high spatial resolution/high contrast imaging modality with specific MRI contrast imaging agents for molecular imaging is currently the focus of research in many laboratories worldwide. This paper summarizes the rationale for molecular MRI imaging and describes the basic features of modern molecular imaging strategies with MRI. Finally, a special focus is given to the growing field of applications, e.g., stem cell imaging, imaging of apoptosis, plaques, and other biological targets of interest.     

Advancing animal models of neoplasia through in vivo bioluminescence imaging

Malignant disease is the final manifestation of complex molecular and cellular events leading to uncontrolled cellular proliferation and eventually tissue destruction and metastases. While the in vitro examination of cultured tumour cells permits the molecular dissection of early pathways in tumorigenesis on cellular and subcellular levels, only interrogation of these processes within the complexity of organ systems of the living animal can reveal the full range of pathophysiological changes that occur in neoplastic disease. Such analyses require technologies that facilitate the study of biological processes in vivo, and several approaches have been developed over the last few years. These strategies, in the nascent field of in vivo molecular and cellular imaging, combine molecular biology with imaging modalities as a means to real-time acquisition of functional information about disease processes in living systems. In this review, we will summarise recent developments in in vivo bioluminescence imaging (BLI) and discuss the potential of this imaging strategy for the future of cancer research.     

Molecular imaging for the characterization of breast tumors

Recently, molecular imaging, using various techniques, has been assessed for breast imaging. Molecular imaging aims to quantify and visualize biological, physiological, and pathological processes at the cellular and molecular levels to further elucidate the development and progression of breast cancer and the response to treatment. Molecular imaging enables the depiction of tumor morphology, as well as the assessment of functional and metabolic processes involved in cancer development at different levels. To date, molecular imaging techniques comprise both nuclear medicine and radiological techniques. This review aims to summarize the current and emerging functional and metabolic techniques for the molecular imaging of breast tumors.     

Special conference of the American Association for Cancer Research on molecular imaging in cancer: linking biology, function, and clinical applications in vivo

The AACR Special Conference on Molecular Imaging in Cancer: Linking Biology, Function, and Clinical Applications In Vivo, was held January 23-27, 2002, at the Contemporary Hotel, Walt Disney World, Orlando, FL. Co-Chairs David Piwnica-Worms, Patricia Price and Thomas Meade brought together researchers with diverse expertise in molecular biology, gene therapy, chemistry, engineering, pharmacology, and imaging to accelerate progress in developing and applying technologies for imaging specific cellular and molecular signals in living animals and humans. The format of the conference was the presentation of research that focused on basic and translational biology of cancer and current state-of-the-art techniques for molecular imaging in animal models and humans. This report summarizes the special conference on molecular imaging, highlighting the interfaces of molecular biology with animal models, instrumentation, chemistry, and pharmacology that are essential to convert the dreams and promise of molecular imaging into improved understanding, diagnosis, and management of cancer.     

Molecular imaging in oncology.

Cancer is a genetic disease that manifests in loss of normal cellular homeostatic mechanisms. The biology and therapeutic modulation of neoplasia occurs at the molecular level. An understanding of these molecular processes is therefore required to develop novel prognostic and early biomarkers of response. In addition to clinical applications, increased impetus for the development of such technologies has been catalysed by pharmaceutical companies investing in the development of molecular therapies. The discipline of molecular imaging therefore aims to image these important molecular processes in vivo. Molecular processes, however, operate at short length scales and concentrations typically beyond the resolution of clinical imaging. Solving these issues will be a challenge to imaging research. The successful implementations of molecular imaging in man will only be realised by the close co-operation amongst molecular biologists, chemists and the imaging scientists.     

Advances in molecular imaging for breast cancer detection and characterization

Advances in our ability to assay molecular processes, including gene expression, protein expression, and molecular and cellular biochemistry, have fueled advances in our understanding of breast cancer biology and have led to the identification of new treatments for patients with breast cancer. The ability to measure biologic processes without perturbing them in vivo allows the opportunity to better characterize tumor biology and to assess how biologic and cytotoxic therapies alter critical pathways of tumor response and resistance. By accurately characterizing tumor properties and biologic processes, molecular imaging plays an increasing role in breast cancer science, clinical care in diagnosis and staging, assessment of therapeutic targets, and evaluation of responses to therapies. This review describes the current role and potential of molecular imaging modalities for detection and characterization of breast cancer and focuses primarily on radionuclide-based methods.     

Molecular imaging in oncology: Current impact and future directions

The authors define molecular imaging, according to the Society of Nuclear Medicine and Molecular Imaging, as the visualization, characterization, and measurement of biological processes at the molecular and cellular levels in humans and other living systems. Although practiced for many years clinically in nuclear medicine, expansion to other imaging modalities began roughly 25 years ago and has accelerated since. That acceleration derives from the continual appearance of new and highly relevant animal models of human disease, increasingly sensitive imaging devices, high-throughput methods to discover and optimize affinity agents to key cellular targets, new ways to manipulate genetic material, and expanded use of cloud computing. Greater interest by scientists in allied fields, such as chemistry, biomedical engineering, and immunology, as well as increased attention by the pharmaceutical industry, have likewise contributed to the boom in activity in recent years. Whereas researchers and clinicians have applied molecular imaging to a variety of physiologic processes and disease states, here, the authors focus on oncology, arguably where it has made its greatest impact. The main purpose of imaging in oncology is early detection to enable interception if not prevention of full-blown disease, such as the appearance of metastases. Because biochemical changes occur before changes in anatomy, molecular imaging—particularly when combined with liquid biopsy for screening purposes—promises especially early localization of disease for optimum management. Here, the authors introduce the ways and indications in which molecular imaging can be undertaken, the tools used and under development, and near-term challenges and opportunities in oncology.     

Optical Coherence Tomography: Feasibility for Basic Research and Image-guided Surgery of Breast Cancer

Diagnostic trends in medicine are being directed toward cellular and molecular processes, where treatment regimens are more amenable for cure. Optical imaging is capable of performing cellular and molecular imaging using the short wavelengths and spectroscopic properties of light. Diffuse optical tomography is an optical imaging technique that has been pursued as an alternative to X-ray mammography. While this technique permits non-invasive optical imaging of the whole breast, to date it is incapable of resolving features at the cellular level. Optical coherence tomography (OCT) is an emerging high-resolution biomedical imaging technology that for larger and undifferentiated cells can perform cellular-level imaging at the expense of imaging depth. OCT performs optical ranging in tissue and is analogous to ultrasound except reflections of near-infrared light are detected rather than sound. In this paper, an overview of the OCT technology is provided, followed by images demonstrating the feasibility of using OCT to image cellular features indicative of breast cancer. OCT images of a well-established carcinogen-induced rat mammary tumor model were acquired. Images from this common experimental model show strong correlation with corresponding histopathology. These results illustrate the potential of OCT for a wide range of basic research studies and for intra-operative image-guidance to identify foci of tumor cells within surgical margins during the surgical treatment of breast cancer.     

Challenges and opportunities for in vivo imaging in oncology

Advances in genomics, proteomics and technology are changing medicine in fundamental ways. There are increasing clinical and laboratory requirements to obtain cellular and molecular information in vivo. This is particularly true in oncology, where the behavior of tumor cells is inextricably linked to their milieu. If cancer cells are removed from their microenvironment, their pattern of gene expression changes. Therefore, non-invasive, quantitative means of detecting gene and protein activity are essential. In vivo imaging is one methodology for achieving this. Marked advances in tracer methods for PET scanning or single-photon nuclear medicine techniques have occurred in the past few years. MRI contrast agents that reflect physiologic information are also being developed, although larger mass quantities of injectable material are required. The useful concept of "activatable agents" was pioneered in MRI. Similarly, ultrasound and computed tomography are being re-engineered to reflect information at the cellular level. In vivo optical imaging technologies have matured to the point where they are indispensable laboratory tools for small animal imaging. Human applications are in the feasibility testing stage, and the future for clinical optical imaging techniques looks bright. Merging these molecular imaging techniques with minimally or non-invasive image-guided therapeutic delivery techniques is a subsequent goal in the fight against cancer.