活体动物体内光学成像技术的研究进展

生物发光和荧光成像作为近年来新兴的活体动物体内光学成像技术,以其操作简便及直观性成为研究小动物活体成像的一种理想方法,在生命科学研究中得以不断发展。利用这种成像技术,可以直接实时观察标记的基因及细胞在活体动物体内的活动及反应。利用光学标记的转基因动物模型可以研究疾病的发生发展过程,进行药物研究及筛选等。本文综述了现有活体动物体内光学成像技术的原理、应用领域及发展前景,比较了生物发光与几种荧光技术的不同特点和应用。     

自发光学信号成像系统在生物成像中的发展与应用

自发光学信号成像系统是近年来比较新颖的一项用于活体生物的基因或细胞活动的微观检测的光学技术,具有直观、操作简便以及分辨率高的特点。该技术主要分为生物发光成像技术和荧光成像技术,目前主要用于测定活体动物体内的细胞以及分子的活动或变化情况。由于该技术能够对动物体内的微观形态的变化进行精确的捕捉,对于癌症、基因表达、肿瘤以及其他病变均具有较好的监测作用。在本文中,将就自发光学信号成像系统在生物成像中的发展与应用进行详细的阐述。     

活体生物发光成像技术及其在病毒感染研究中的应用

生物发光是动物活体光学成像技术之一,因其反应灵敏、操作简单、数据精确,而被广泛地应用于生命科学研究多个领域,观测活体动物体内病毒复制、肿瘤生长等生命过程.生物发光技术采用荧光素酶基因标记细胞或病毒,与外源注射的底物荧光素发生反应,在冷CCD成像系统下显像并进行数据记录、分析.本文简要介绍活体生物发光成像这一新技术的原理...     

在体生物发光成像技术在生物医学中的应用

在体生物发光成像技术采用萤光素酶基因标记细胞及DNA,利用灵敏的光学检测仪器,实时直观地监测活体小动物体内感染性疾病的发生发展、肿瘤的生长及转移及引发的免疫反应、特定基因的表达等诸多生物过程。通过对同一组实验对象在不同时间点进行记录,跟踪同一观察目标(标记细胞、病原微生物或基因)的移动及变化,与传统的动物实验方法相比,在体生物发光成像得到的数据具有更高的可信度。近年来因其灵敏度较高、不涉及放射性物质、所得结果直观等优势,该技术已普遍应用于生物医学、药物开发等研究领域。     

重组腺相关病毒小鼠骨骼肌中近红外荧光蛋白表达及活体成像

近红外荧光蛋白因激发光和发射光波长位于近红外区,在动物组织中光吸收和光散射最低,更适宜于动物活体组织的深层成像.构建了一种携带近红外荧光蛋白(near-infrared fluorescent protein,iRFP)713基因的重组表达质粒pAAV-iRFP713,将重组表达质粒与辅助质粒共转染AAV-293细胞,包装重组腺相关病毒(recombinant adeno-associated virus,rAAV)rAAV-iRFP713.重组腺相关病毒表达载体感染体外培养的癌细胞,48h后,荧光显微镜检测显示近红外荧光蛋白在癌细胞中高效表达,荧光明亮.重组腺相关病毒表达载体注射小鼠骨骼肌,48h后,用近红外荧光活体成像系统检测证明近红外荧光蛋白在小鼠骨骼肌中表达较强, 活体组织成像清晰.实验结果表明近红外荧光蛋白在体内体外均能很好地表达并荧光成像,为动物活体组织标记和成像的研究提供新方法.     

小动物体内可见光三维成像技术研究进展

活体动物体内可见光成像是采用生物发光和荧光为标记物,利用灵敏的仪器来监控活体动物体内的细胞活动、蛋白表达情况和基因行为。近年来,可见光成像在生物医学的各个方面得到了广泛的应用。随着成像技术和检测仪器的不断发展,现已从平面二维成像逐渐发展为立体三维成像。三维成像技术在靶点的空间定位、与器官的关系,及绝对定量方面都有了很大的进展。本文就三维成像技术的原理、应用和发展前景进行了简要的综述。     

活体光学成像技术在TGF-β1信号通路调控乳腺癌转移作用中的应用北大核心CSCD

活体动物光学成像技术因具有无创伤、活体、动态、连续、特异显像等优点,已被广泛应用于细胞的体内示踪或特定基因体内表达的实时监测研究。TGF-β1信号通路在乳腺癌的发生、发展和转移过程中起着十分重要的作用。本文主要对活体动物光学成像技术在研究TGF-β1信号通路调控乳腺癌转移作用中的应用进行综述,讨论乳腺癌的体内转移过程与TGF-β1信号通路的相关性,最后对黄酮类化合物干预乳腺癌转移的作用进行总结。因此,本文可为筛选抗乳腺癌转移的新型药物提供一定的理论指导,推动分子影像技术在活体动态连续观测药物治疗效果方面的应用。     

SW1990和Capan-2红色荧光标记胰腺癌移植肿瘤模型的建立和比较

目的建立稳定表达红色荧光蛋白基因的人胰腺癌细胞系,为体内监测肿瘤的早期生长及抗肿瘤药物的药效评价建立一种新的肿瘤动物模型。方法以Lipofectamine 2000介导chickenβ-actin-RFP-NEO转染人胰腺癌细胞SW1990和Capan-2,经梯度浓度G418筛选获得稳定表达红色荧光蛋白的细胞克隆并扩大培养。BALB/cA-nu裸鼠皮下接种1×106个发光细胞使其成瘤,活体荧光成像系统观察肿瘤的生长情况。结果获得了稳定表达RFP的两种不同的人胰腺癌细胞株,将其接种到裸鼠体内可成瘤,利用活体成像系统观察了肿瘤的生长动态过程,并且SW1990肿瘤细胞的生长速度较Capan-2细胞快。结论用红色荧光蛋白标记的人胰腺癌细胞建立的裸鼠肿瘤模型为胰腺癌的研究和相关药物筛选提供了可进行荧光影像活体、动态分析的动物模型。     

人结肠腺癌细胞HCT－8绿色荧光标记肿瘤模型的建立

目的筛选表达绿色荧光蛋白基因的人的单克隆结肠腺癌细胞系,为体内监测肿瘤的早期生长建立一种新的肿瘤动物模型。方法以脂质体2000介导chicken β－acfin-GFP—NEO转染人结肠腺癌细胞HCT－8,经梯度浓度G418筛选获得稳定表达绿色荧光蛋白的细胞克隆并扩大培养。BALB／CA－nu裸鼠皮下接种1×10^6个发光细胞使其成瘤,活体荧光成像系统观察肿瘤的生长情况。结果获得了稳定表达GFP的人结肠腺癌细胞株,将其接种到裸鼠体内可成瘤,利用活体成像系统观察了肿瘤的生长过程,肿瘤的发光随着观察时间的延长而增加。结论绿色荧光蛋白能够在人结肠腺癌细胞HCT-8中长期稳定表达,用绿色荧光蛋白标记的人结肠腺癌细胞HCT-8建立的裸鼠肿瘤模型为进一步研究结肠肿瘤和相应的药物筛选提供了一种简便、可行的新方法。     

荧光素酶标的人肝癌细胞裸鼠异种移植瘤模型的生物发光成像和PET-CT成像比较

目的利用荧光素酶基因标记的人肝癌细胞株BEL-7402建立裸鼠肝原位移植模型,及小鼠肝原位移植模型的生物发光和小动物PET-CT成像的比较。方法构建表达荧光素酶基因的真核表达载体并将其转入人肝癌细胞BEL-7402,经梯度浓度G418筛选获得稳定表达荧光素酶基因的细胞克隆并扩大培养。BALB/cA-nu裸鼠肝门静脉接种5×105个发光细胞使其成瘤,活体荧光成像和小动物PET-CT成像系统观察肿瘤的生长情况。结果获得了稳定表达Luc的人肝癌细胞株,将其接种到裸鼠体内,活体荧光成像系统观察发现能够成瘤,小动物PET-CT影像观察发现小鼠肝脏边缘对18 F-FDG有高摄取区域。结论利用荧光素酶基因标记的人肝癌细胞BEL-7402成功建立了原位肝癌裸鼠模型,小动物活体成像结合小动物PET-CT技术为原位肿瘤模型的建立提供了一种新的可靠的技术,为进一步研究肝癌生长转移机制和药物开发提供了新的有用工具。     

Antisense imaging: And miles to go before we sleep?

Labeled oligonucleotide analogues for antisense imaging of messenger RNA (mRNA) have great potential for detection of endogenous gene expression in vivo. Successful antisense imaging may be useful for detecting cellular gene expression patterns and early molecular changes in disease. Conclusive demonstration of this technique has been hindered by formidable challenges in surmounting biological barriers and detecting low concentrations of target mRNA. Recent advances in the development of novel antisense molecules, high specific activity radiolabeling chemistry, sophisticated drug targeting technology, and complementary molecular imaging modalities make it quite possible that true antisense imaging will be realized in the near future.     

In vivo tomographic imaging of near-infrared fluorescent probes

Fluorescence imaging is increasingly used to probe protein function and gene expression in live animals. This technology could enhance the study of pathogenesis, drug development, and therapeutic intervention. In this article, we focus on three-dimensional fluorescence observations using fluorescence-mediated molecular tomography (FMT), a novel imaging technique that can resolve molecular function in deep tissues by reconstructing fluorescent probe distributions in vivo. We have compared FMT findings with conventional fluorescence reflectance imaging (FRI) to study protease function in nude mice with subsurface implanted tumors. This validation of FMT with FRI demonstrated the spatial congruence of fluorochrome activation as determined by the two techniques.     

萤光素酶表达质粒pEE14.1-luc的构建及表达

目的:为研究10 kb以上DNA疫苗质粒的体内电穿孔递送,构建萤光素酶报告基因表达质粒p EE14.1-luc,并验证其表达。方法:从质粒p GL3-CMV中通过酶切、补平和纯化的方法获得萤光素酶基因luc,克隆入p EE14.1载体,构建重组表达质粒p EE14.1-luc,瞬时转染293T细胞,采用Western印迹、流式细胞术和免疫荧光等方法对萤光素酶基因在体外的表达情况进行验证,并运用活体成像仪检测萤光素酶基因在小鼠活体内的表达。结果:经菌液PCR鉴定和测序验证,p EE14.1-luc与预期设计完全一致;流式细胞术检测luc阳性表达率为22.41%,免疫荧光检测可见绿色荧光表达,Western印迹检测在相对分子质量为62×103处显现目的蛋白条带;同时,利用活体成像技术也检测到萤光素酶基因在小鼠活体内的表达。结论:p EE14.1-luc表达质粒构建成功,为研究DNA疫苗体内表达机制和体内电穿孔递送条件优化奠定了基础。     

Retrofitting baculoviral vector with Sleeping Beauty transposon system: competent for long-term reporter gene imaging in vivo

Reporter gene imaging is widely used for non-invasively detecting tumorigenesis, trafficking therapeutic cells, and monitoring treatment effect. Baculoviral vectors (BVs) have been utilized as transgenic vectors in the reporter gene imaging systems in recent years. However, BV-mediated report gene imaging can only provide short-term investigation due to its transient transgene expression, which is incompetent for the long-term applications. In the current study, we reconstructed a series of hybrid BVs with several elements, to investigate the feasibility of this hybrid BV-mediated long-term reporter gene imaging in vivo. We showed that with the indispensable assistance of a positive-selection process, hybrid BV containing Sleeping Beauty 100× (SB) transposon system (BV-SB) could significantly prolong the enhanced green fluorescent protein (eGFP) expression for at least 180 days in vitro at nearly 100% eGFP positive percentage and over 10¹¹ arbitrary unit total fluorescence intensity, whereas other hybrid BV-mediated transgene expression gradually faded in only 20 days. Furthermore, BV-SB-mediated eGFP fluorescent reporter gene imaging monitored tumorigenesis in the nude mice for at least 35 days. In addition, we exploited the glucagon-like peptide 1 receptor (glp-1r) gene as a radionuclide reporter gene for in vivo micro-PET imaging. At 50th day post-tumor transplantation, the micro-PET imaging showed considerable radiotracer-receptor-binding in vivo, resulted by stable high level of BV-SB-mediated GLP-1R expression in tumor. In summary, we retrofitted BV with the SB transposon system to make it competent for the long-term reporter gene imaging in vivo, which might broaden the application scopes of BV in the long-term molecular imaging and other biomedicine research fields.

     

Real-time in vivo bioluminescence imaging of lentiviral vector-mediated gene transfer in mouse testis

Although much research has focused on transferring exogenous genes into living mouse testis to investigate specific gene functions in spermatogenic, Sertoli, and Leydig cells, relatively little is known regarding real-time gene expression in vivo. In this study, we constructed a bicistronic lentiviral vector (LV) encoding firefly luciferase and enhanced green fluorescence protein (EGFP); this was a highly efficient in vivo gene transfer tool. After microinjecting LV into the seminiferous tubules the ICR mouse testis, we detected luciferase and EGFP expression in vivo and ex vivo in the injected tubules using bioluminescence imaging (BLI) with the IVIS-200 system and fibered confocal fluorescence microscopy (CellViZio), respectively. In addition, with an in vivo BLI system, luciferase expression in the testis was detected for ∼3 mo. Furthermore, EGFP expression in seminiferous tubules was confirmed in excised testes via three-dimensional fluorescent imaging with a confocal laser-scanning microscope. With immunostaining, EGFP expression was confirmed in several male germ cell types in the seminiferous tubules, as well as in Sertoli and Leydig cells. In conclusion, we demonstrated that real-time in vivo BLI analysis can be used to noninvasively (in vivo) monitor long-term luciferase expression in mouse testis, and we verified that EGFP expression is localized in seminiferous tubules after bicistronic LV-mediated gene transfer into mouse testes. Furthermore, we anticipate the future use of in vivo BLI technology for real-time study of specific genes involved in spermatogenesis.     

Single-cell electroporation for gene transfer in vivo

We report an electroporation technique for targeting gene transfer to individual cells in intact tissue. Electrical stimulation through a micropipette filled with DNA or other macromolecules electroporates a single cell at the tip of the micropipette. Electroporation of a plasmid encoding enhanced green fluorescent protein (GFP) into the brain of intact Xenopus tadpoles or rat hippocampal slices resulted in GFP expression in single neurons and glia. In vivo imaging showed morphologies, dendritic arbor dynamics, and growth rates characteristic of healthy cells. Coelectroporation of two plasmids resulted in expression of both proteins, while electroporation of fluorescent dextrans allowed direct visualization of transfer of molecules into cells. This technique will allow unprecedented spatial and temporal control over gene delivery and protein expression.     

In vivo optical molecular imaging and analysis in mice using dorsal window chamber models applied to hypoxia, vasculature and fluorescent reporters

Optical techniques for functional imaging in mice have a number of key advantages over other common imaging modalities such as magnetic resonance imaging, positron emission tomography or computed tomography, including high resolution, low cost and an extensive library of available contrast agents and reporter genes. A major challenge to such work is the limited penetration depth imposed by tissue turbidity. We describe a window chamber technique by which these limitations can be avoided. This facilitates the study of a wide range of processes, with potential endpoints including longitudinal gene expression, vascular remodeling and angiogenesis, and tumor growth and invasion. We further describe several quantitative imaging and analysis techniques for characterizing in vivo fluorescence properties and functional endpoints, including vascular morphology and oxygenation. The procedure takes ～2 h to complete, plus up to several weeks for tumor growth and treatment procedures.     

水动力转染基因在小鼠体内的长期高效表达

水动力转染技术是近年新出现的一种体内基因转染方法,可以实现目的基因在小鼠体内的高效表达,有可能作为受精卵显微注射的一种简单替代技术。但该技术的缺点是转染基因多瞬时表达,外源基因在体内高效表达的时间通常不超过1周,而且局限于肝、肾等器官,从而限制了该技术广泛应用。为了延长水动力转染基因在小鼠体内长期高效表达的时间,从而能对目的基因的体内功能进行长期研究,国外研究进行了广泛的探索,本综述了相关研究的最新进展。     

Switching on the lights for gene therapy

Strategies for non-invasive and quantitative imaging of gene expression in vivo have been developed over the past decade. Non-invasive assessment of the dynamics of gene regulation is of interest for the detection of endogenous disease-specific biological alterations (e.g., signal transduction) and for monitoring the induction and regulation of therapeutic genes (e.g., gene therapy). To demonstrate that non-invasive imaging of regulated expression of any type of gene after in vivo transduction by versatile vectors is feasible, we generated regulatable herpes simplex virus type 1 (HSV-1) amplicon vectors carrying hormone (mifepristone) or antibiotic (tetracycline) regulated promoters driving the proportional co-expression of two marker genes. Regulated gene expression was monitored by fluorescence microscopy in culture and by positron emission tomography (PET) or bioluminescence (BLI) in vivo. The induction levels evaluated in glioma models varied depending on the dose of inductor. With fluorescence microscopy and BLI being the tools for assessing gene expression in culture and animal models, and with PET being the technology for possible application in humans, the generated vectors may serve to non-invasively monitor the dynamics of any gene of interest which is proportionally co-expressed with the respective imaging marker gene in research applications aiming towards translation into clinical application.     

Preclinical applications of imaging for cancer gene therapy

Gene therapy is a very attractive strategy in experimental cancer therapy. Ideally, the approach aims to deliver therapeutic genes selectively to cancer cells. However, progress in the improvement of gene therapy formulations has been hampered by difficulties in measuring transgene delivery and in quantifying transgene expression in vivo. In clinical trials, endpoints rely almost exclusively on the analysis of biopsies by molecular and histopathological methods, which provide limited information. Therefore, to ensure the rational development of gene therapy, a crucial issue is the utilisation of technologies for the non-invasive monitoring of spatial and temporal gene expression in vivo upon administration of a gene delivery vector. Such imaging technologies would allow the generation of quantitative information about gene expression and the assessment of cancer gene therapy efficacy. In the past decade, progress has been made in the field of in vivo molecular imaging. This review highlights the various methods currently being developed in preclinical models.