Imaging In Mouse Model Research Articles

Systematic evaluation of 99mTc-tetrofosmin versus 99mTc-sestamibi to study murine myocardial perfusion in small animal SPECT/CT

BackgroundThe “back-translation” of clinically available protocols to measure myocardial perfusion to preclinical imaging in mouse models of human disease is attractive for basic biomedical research. With respect to single-photon emission computed tomography (SPECT) approaches, clinical myocardial perfusion imaging protocols are established with different 99mTc-labeled perfusion tracers; however, studies evaluating and optimizing protocols for these tracers in high-resolution pinhole SPECT in mice are lacking. This study aims at evaluating two clinically available 99mTc-labeled myocardial perfusion tracers (99mTc-sestamibi vs. 99mTc-Tetrofosmin) in mice using four different imaging protocols.MethodsAdult C57BL/6 male mice were injected with 99mTc-sestamibi (MIBI) or 99mTc-Tetrofosmin (TETRO) (4 MBq/g body weight) either intravenously through the tail vein (n = 5) or retroorbitally (n = 5) or intraperitoneally (i.p.) under anesthesia (n = 3) or i.p. in an awake state (n = 3) at rest. Immediately after injection, a multi-frame single-photon emission computed tomography/computed tomography (SPECT/CT) acquisition was initiated with six subsequent time frames of 10 min each. Reconstructed images of the different protocols were assessed and compared by visual analysis by experts and by time-activity-curves generated from regions-of-interest for various organs (normalized uptake values).ResultsVisually assessing overall image quality, the best image quality was found for MIBI for both intravenous injection protocols, whereas TETRO only had comparable image quality after retroorbital injections. These results were confirmed by quantitative analysis where left ventricular (LV) uptake of MIBI after tail vein injections was found significantly higher for all time points accompanied with a significantly slower washout of 16% for MIBI vs. 33% for TETRO (p = 0.009) from 10 to 60 min post injection (PI). Interestingly, LV washout from 10 to 60 min PI was significantly higher for TETRO when applied by tail vein injections when compared to retroorbital injections (22%, p = 0.008). However, liver uptake was significant and comparable for both tracers at all time points. Radioactivity concentration in the lungs was negligible for all time points and both tracers.ConclusionIntravenous MIBI injection (both tail vein and retroorbital) results in the best image quality for assessing myocardial perfusion of the murine heart by SPECT/CT. TETRO has a comparable image quality only for the retroorbital injection route.

Axonal injury in reverse

Axonal damage causes neurological defects in multiple sclerosis. In vivo imaging in mouse models of multiple sclerosis now shows a reversible and sequential process of focal axonal degeneration (FAD) (pages 495–499), suggesting the use of neuroregenerative as well as neuroprotective drugs as potential therapies for multiple sclerosis.

Multimodality Optical Imaging of Mouse Model of Tongue Carcinogenesis: Correlation With Histopathologic and Molecular Features

Multimodality Optical Imaging of Mouse Model of Tongue Carcinogenesis: Correlation With Histopathologic and Molecular Features

Multimodality Optical Imaging of Mouse Model Of Tongue Carcinogenesis: Correlation With Histopathologic and Molecular Features

Multimodality Optical Imaging of Mouse Model Of Tongue Carcinogenesis: Correlation With Histopathologic and Molecular Features

Development of a highly metastatic model that reveals a crucial role of fibronectin in lung cancer cell migration and invasion

BackgroundThe formation of metastasis is the most common cause of death in patients with lung cancer. A major implement to understand the molecular mechanisms involved in lung cancer metastasis has been the lack of suitable models to address it. In this study, we aimed at establishing a highly metastatic model of human lung cancer and characterizing its metastatic properties and underlying mechanisms.MethodsThe human lung adeno-carcinoma SPC-A-1 cell line was used as parental cells for developing of highly metastatic cells by in vivo selection in NOD/SCID mice. After three rounds of selection, a new SPC-A-1sci cell line was established from pulmonary metastatic lesions. Subsequently, the metastatic properties of this cell line were analyzed, including optical imaging of in vivo metastasis, immunofluorescence and immunohistochemical analysis of several epithelial mesenchymal transition (EMT) makers and trans-well migration and invasion assays. Finally, the functional roles of fibronectin in the invasive and metastatic potentials of SPC-A-1sci cells were determined by shRNA analysis.ResultsA spontaneously pulmonary metastatic model of human lung adeno-carcinoma was established in NOD/SCID mice, from which a new lung cancer cell line, designated SPC-A-1sci, was isolated. Initially, the highly metastatic behavior of this cell line was validated by optical imaging in mice models. Further analyses showed that this cell line exhibit phenotypic and molecular alterations consistent with EMT. Compared with its parent cell line SPC-A-1, SPC-A-1sci was more aggressive in vitro, including increased potentials for cell spreading, migration and invasion. Importantly, fibronectin, a mesenchymal maker of EMT, was found to be highly expressed in SPC-A-1sci cells and down-regulation of it can decrease the in vitro and in vivo metastatic abilities of this cell line.ConclusionsWe have successfully established a new human lung cancer cell line with highly metastatic potentials, which is subject to EMT and possibly mediated by increased fibronectin expression. This cell line and its reproducible s.c. mouse model can further be used to identify underlying mechanisms of lung cancer metastasis.

Establishment of in vivo fluorescence imaging in mouse models of malignant mesothelioma

Malignant mesothelioma is a highly aggressive tumor with poor prognosis, and new treatment paradigms are urgently needed. For testing preclinical efficacy of new therapeutic agents, establishment of appropriate animal models is crucial. We developed in vivo fluorescence imaging models for human malignant mesothelioma in mice using tumor cells engineered to express fluorescent proteins (EGFP, mRFP, mCherry, and mPlum) by lentiviral vectors. Among these fluorescent proteins, the expression of mCherry protein in the transduced tumor cells was shown to be robust and stable both in vitro and in vivo. In both, peritoneally disseminated and orthotopic pleural mesothelioma models, mCherry-positive tumors were sensitively detected and tumor growth was successfully monitored. This represents the first study to achieve sensitive tumor detection and tracking of tumor growth and development in the malignant mesothelioma mouse models by non-invasive in vivo fluorescence imaging. These imaging models can be versatile and powerful tools to explore new treatment paradigms for malignant mesothelioma.

Abstract 3236: High-sensitivity, high-resolution multispectral fluorescence imaging of small (and very small) animals

Abstract in vivo multispectral imaging (MSI) increases the sensitivity and usefulness of small animal models of development and disease, including the most popular and promising experimental systems. In mice, MSI can essentially eliminate autofluorescence that otherwise limits sensitivity, reducing detection limits by as much as 100-fold. Fluorescence imaging is a key technology for determining the where, the when and the how much of gene expression. However, the ability to image and quantitate fluorescently labeled markers in vivo has typically been limited by the bright autofluorescence of animal tissues. Small-animal imaging, which often means the imaging of mouse models, encounters autofluorescence primarily from components in skin (collagen, which fluoresces green) and food (chlorophyll, which fluoresces red). However, other small animal model systems, such as nematodes (C. elegans), zebrafish (D. rerio) embryos or adult fish, and fruit flies (D. melanogaster) pose similar problems due to the presence of autofluorescent structures that may render common labeling strategies, including the use of green fluorescent protein (GFP) labels, problematic. Various solutions have been proposed for the reduction or elimination of autofluorescence. The most prevalent is simply to use narrow bandpass emission filters in an effort to isolate the desired fluorescence signal [1]. More recently, there has been a move to use infrared-emitting labels that are excited at wavelengths that are much less likely to induce autofluorescence signals. However, autofluorescence still limits sensitivity. Fortunately, the low signal-to-background contrast problem created by autofluorescence can be substantially eliminated using MSI techniques. Moreover, MSI permits the simultaneous use of multiple labels, such as GFP and RFP, even when they spectrally overlap with themselves or autofluorescence [2]. Presented here are the results of applying an MSI strategy to the whole-animal in vivo imaging of mice, C. elegans, D. rerio and D. melanogaster at a variety of magnifications, ranging from the imaging of three whole mice simultaneously down to microscopic images of whole animals and embryos. This is accomplished using a liquid crystal tunable filter (LCTF)-based imaging system that has been adapted to either a C-mount on a fluorescence microscope or macroscope, or incorporated into a whole-animal imaging system. In each case, the sensitivity of the fluorescence measurement was greatly improved by using a MSI approach. Rapid, quantitative, imaging of GFP signals of up to a few hundred flies simultaneously in a few seconds can be easily achieved, as can high-sensitivity microscopic imaging of GFP in nematode worms. These types of imaging experiments are of value to anyone with whole-animal fluorescence-based models. [1] Niswender KD et al, J Microsc 180, 109-116 (1995) [2] Levenson, et al, Cytometry A. 2006 Aug; 69(8):748-58 Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3236.

Bioluminescence Imaging in Mouse Models Quantifies β Cell Mass in the Pancreas and After Islet Transplantation

We developed a mouse model that enables non-invasive assessment of changes in beta cell mass. We generated a transgenic mouse expressing luciferase under control of the mouse insulin I promoter [mouse insulin promoter-luciferase-Vanderbilt University (MIP-Luc-VU)] and characterized this model in mice with increased or decreased beta cell mass and after islet transplantation. Streptozotocin-induced, diabetic MIP-Luc-VU mice had a progressive decline in bioluminescence that correlated with a decrease in beta cell mass. MIP-Luc-VU animals fed a high-fat diet displayed a progressive increase in bioluminescence that reflected an increase in beta cell mass. MIP-Luc-VU islets transplanted beneath the renal capsule or into the liver emitted bioluminescence proportional to the number of islets transplanted and could be imaged for more than a year. Bioluminescence in the MIP-Luc-VU mouse model is proportional to beta cell mass in the setting of increased and decreased beta cell mass and after transplantation.

Synthesis and characterization of 6-deoxy-6-fluoro- d-fructose as a potential compound for imaging breast cancer with PET

FDG-based imaging with positron emission tomography (PET) has been widely used in the detection of cancer, but has not reached its full potential. In breast cancer, the glucose/fructose transporter GLUT2 and the fructose transporter GLUT5 are known to be overexpressed in transformed tissues, implicating that a fructose-based analogue would be a useful target for the improved imaging of breast cancer. We have successfully synthesized the fluorinated fructose compound, 6-deoxy-6-fluoro- d-fructose (6FDF) and examined its potential for transport and accumulation in breast cancer cells. Expression analysis of GLUT isoforms was performed on two GLUT5 expressing breast cancer cell lines using western blotting and immunocytochemistry. Uptake and inhibition studies were undertaken using [14C]-labelled hexoses. Transport inhibition studies showed dose dependent inhibition of fructose transport in both cell lines by the newly synthesized 6-deoxy-6-fluoro- d-fructose (6FDF). Also, near linear uptake over time of [14C]-labelled 6FDF was observed in both cell lines. It appears that 6FDF may have great promise for use in in vivo PET imaging of breast cancer. Ongoing work will confirm the efficacy of this compound in imaging in mouse models.

Microscintigraphy with high resolution collimators and radiographic detectors

The potential use of high resolution collimators with standard radiographic detectors in place of conventional gamma cameras for high resolution microscintigraphy is presented. Polycapillary multiple hole collimators are shown to provide 10-100 micron scale spatial resolution. A series of images from arrays of 125I brachytherapy seeds in Lucite phantoms display resolution better than 0.1 mm with good sensitivity and a 30 mm field of view. In addition to application to brachytherapy seed localization, such "cellular" level resolution is necessary for high-resolution in vivo imaging in mouse models. The system could also enable the use of a wider variety of isotopes, including much lower photon energy isotopes in nuclear medicine, as the high resolution collimator allows more flexibility in detector constraints.

Mouse behavioral mutants have neuroimaging abnormalities

Impaired cognitive, memory, or motor performance is a distinguishing characteristic of neurological diseases. Although these symptoms are frequently the most evident in human patients, additional markers of disease are critical for proper diagnosis and staging. Noninvasive neuroimaging methods have become essential in this capacity and provide means of evaluating disease and tracking progression. These imaging methods are also becoming available to scientists in the research laboratory for assessment of animal models of neurological disease. Imaging in mouse models of neurological disease is of particular interest, owing to the availability of inbred strains and genetic manipulation tools that permit detailed investigation of the roles of various genes and gene products in disease pathogenesis. However, the relative prevalence of neuroimaging abnormalities in mice exhibiting neurological symptoms has not been reported. This prevalence has both theoretical and practical value because it is influenced by both the sensitivity of macroscopic anatomical measures to underlying genetic and disease processes and by the efficiency of neuroimaging in detecting and characterizing these effects. In this paper, we describe a meta-analysis of studies involving behavioral mouse mutants at our laboratory. In summary, we have evaluated 15 different mutant genotypes, of which 13 showed abnormal neuroimaging findings. This indicates a surprisingly high prevalence of neuroimaging abnormalities (87%) and suggests that disease processes affecting behavior generally alter neuroanatomy as well. As a consequence, neuroimaging provides a highly sensitive marker of neurological disease in mice exhibiting abnormal behavior.

Role of molecular imaging in mouse models of cardiac diseases-small animal-PET to elucidate the pathophysiology in survivin-deficient mice

Role of molecular imaging in mouse models of cardiac diseases-small animal-PET to elucidate the pathophysiology in survivin-deficient mice