In vivo imaging in experimental preclinical tumor research–A review

Abstract

The multiparametric molecular cell and tissue analysis in vitro and in vivo is characterized by rapid progress in the field of image generation technologies, sensor biotechnology, and computational modeling. Fascinating new potentials in unraveling the detailed functions of single cells, organs, and whole organisms are presently emerging and permit the close monitoring i.e. tumor development or basic cell development processes with an unprecedented multiplicity of promising investigative possibilities. To answer basic questions of in vivo tumor development and progression fluorescence based imaging techniques provide new insights into molecular pathways and targets. Genetic reporter systems (eGFP, DsRED) are available and high sensitive detection systems are on hand. These techniques could be used for in vitro assays and quantified e.g. by microscopy and CCD based readouts. The introduction of novel fluorescent dyes emitting in the near infrared range (NIR) combined with the development of sensitive detector systems and monochromatic powerful NIR-lasers for the first time permits the quantification and imaging of fluorescence and/or bioluminescence in deeper tissues. Laser based techniques particularly in the NIR-range (like two-photon microscopy) offer superb signal to noise ratios, and thus the potential to detect molecular targets in vivo. In combination with flat panel volumetric computed tomography (fpVCT), questions dealing e.g. with tumor size, tumor growth, and angiogenesis/vascularization could be answered noninvasively using the same animal. The resolution of down to 150 lm/each direction can be achieved using fpVCT. It is demonstrated by many groups that submillimeter resolutions can be achieved in small animal imaging at high sensitivity and molecular specificity. Since the resolution in preclinical small animal imaging is down to $10 lm by the use of microCT and to subcellular resolutions using ($1 lm) microscope based systems, the advances of different techniques can now be combined to ''multimodal'' preclinical imaging and the possibilities for in vivo intravital cytometry now become within one's reach. ' International Society for Analytical CytologyKey terms molecular imaging; optical imaging; tumor imaging; fpVCT; near infrared range imaging; renal cell carcinoma; in vivo cytometry; fluorescence in vivo imaging MOLECULAR AND OPTICAL IMAGING--DEFINITIONSMolecular Imaging is a rapidly expanding field in which the modern tools of molecular cell biology are being married to state of the art technology for noninvasive imaging.Within the last years, crucial improvements, notably in optical resolution, have been made. This is a very promising field which actually aims at developing different tools, reagents, and methods to image specific molecular pathways in humans and animals, e.g. those that are key targets in tumor development.Many of these novel imaging techniques could be used for preclinical small animal imaging, for example tumor research, today. Next to fascinating high resolution, t...

Quantification of green fluorescent protein by in vivo imaging, PCR, and flow cytometry: Comparison of transgenic strains and relevance for fetal cell microchimerism

“…One solution may be the incorporation of spectral deconvolution into the methodology described here, leading to improvement of imaging quality through the highly specific discrimination between overlapping fluorescent signals (i.e. real and autofluorescence) (10).…”

“…We assessed each of these two strains using three different techniques: PCR, in vivo imaging (9,10) as well as the imaging of explanted organs using the same technique (ex vivo imaging), and flow cytometry (FCM). We compared transgenic strains to each other and to their respective wild-type background.…”

Episcopic 3D Imaging Methods: Tools for Researching Gene Function

“…Thus the last decades saw the development of a vast number of methods for creating 3D information of cell, tissue, and organ morphology, 3D information of gene expression and gene product patterns, or both. Examples for techniques capable of analyzing small specimens, such as tissue samples or embryos are: in vivo microscopy [7][8][9][10], microcomputed tomography ( CT) [11][12][13], micro-magnetic resonance imaging ( MRI) [9,[14][15][16][17][18], ultrasound biomicroscopy (UBM) [19][20][21], optical projection tomography (OPT) [22,23], confocal microscopy [24][25][26][27][28], atomic force microscopy [29][30][31], 3D electron tomography [32,33], histological or macroscopic section based 3D reconstruction methods [34][35][36][37][38], and 3D episcopic imaging methods (see below). This paper does not compare all the different methods for volume data generation and gene expression analysis.…”

Three-Dimensional (3D) Visualisation of the Cardiovascular System of Mouse Embryos and Fetus

“…They are either optimised for diagnosing pathologies in humans (computed tomography (CT), magnetic resonance imaging (MRI), ultrasound (US), single photon emission computed tomography (SPECT), positron emission tomography (PET)), for in vivo analysis of -often transparent -model animals [23][24][25][26][27][28][29][30][31][32], or for post-mortem analyses of entire biological specimens and biological tissue samples, on the molecular, subcellular, cellular, tissue, and organ system level (atomic force microscopy, electron microscopy, confocal imaging, optical projection tomography (OPT), episcopic imaging techniques, histological sectioning, micro-MRI, micro-CT, near infrared imaging techniques, polarised light spectroscopy, optical coherence tomography (OCT)). Not all of these techniques permit 3D imaging of the developing cardiovascular system of unborn mice.…”