Citation Details

Journal Article

angiogenesis imaging; in vivo imaging; Angiogenesis; Bioluminescence; Fluorescence; Molecular imaging; Optical imaging

In recent years, molecular imaging gained significant importance in biomedical research. Optical imaging developed into a modality which enables the visualization and quantification of all kinds of cellular processes and cancerous cell growth in small animals. Novel gene reporter mice and cell lines and the development of targeted and cleavable fluorescent “smart” probes form a powerful imaging toolbox. The development of systems collecting tomographic bioluminescence and fluorescence data enabled even more spatial accuracy and more quantitative measurements. Here we describe various bioluminescent and fluorescent gene reporter models and probes that can be used to specifically image and quantify neovascularization or the angiogenic process itself.

Journal Article

matrix metalloproteinase; neuroendocrine; prostate cancer; metatasis

Prostate cancer is the leading form of cancer in men. Prostate tumors often contain neuroendocrine differentiation, which correlates with androgen-independent progression and poor prognosis. Matrix metalloproteinases (MMP), a family of enzymes that remodel the microenvironment, are associated with tumorigenesis and metastasis. To evaluate MMPs during metastatic prostatic neuroendocrine cancer development, we used transgenic mice expressing SV40 large T antigen in their prostatic neuroendocrine cells, under the control of transcriptional regulatory elements from the mouse cryptdin-2 gene (CR2-TAg). These mice have a stereotypical pattern of tumorigenesis and metastasis. MMP-2, MMP-7, and MMP-9 activities increased concurrently with the transition to invasive metastatic carcinoma, but they were expressed in different prostatic cell types: stromal, luminal epithelium, and macrophages, respectively. CR2-TAg mice treated with AG3340/Prinomastat, an MMP inhibitor that blocks activity of MMP-2, MMP-9, MMP-13, and MMP-14, had reduced tumor burden. CR2-TAg animals were crossed to mice homozygous for null alleles of MMP-2, MMP-7, or MMP-9 genes. At 24 weeks CR2-TAg; MMP-2-/- mice showed reduced tumor burden, prolonged survival, decreased lung metastasis, and decreased blood vessel density, whereas deficiencies in MMP-7 or MMP-9 did not influence tumor growth or survival. Mice deficient for MMP-7 had reduced endothelial area coverage and decreased vessel size, and mice lacking MMP-9 had increased numbers of invasive foci and increased perivascular invasion, as well as decreased tumor blood vessel size. Together, these results suggest distinct contributions by MMPs to the progression of aggressive prostate tumor and to helping tumors cleverly find alternative routes to malignant progression.

Journal Article

brain tumor; glioma; human neural stem cells; TSP-1; endothelial cells; angiogenesis; in vivo imaging

Novel therapeutic agents combined with innovative modes of delivery and non-invasive imaging of drug delivery, pharmacokinetics and efficacy are crucial in developing effective clinical anticancer therapies. In this study, we have created and characterized multiple novel variants of anti-angiogenic protein thrombospondin (aaTSP-1) that comprises unique regions of three type-I-repeats of TSP-1 and used engineered human neural stem cells (hNSC) to provide sustained on-site delivery of secretable aaTSP-1 to tumor-vasculature. We show that hNSC-aaTSP-1 has anti-angiogenic effect on human brain and dermal microvascular endothelial cells co-cultured with established glioma cells and CD133+ glioma-initiating cells. Using human glioma cells and hNSC engineered with different combinations of fluorescent and bioluminescent marker proteins and employing multi-modality imaging techniques, we show that aaTSP-1 targets the vascular-component of gliomas and a single administration of hNSC-aaTSP-1 markedly reduces tumor vessel-density that results in inhibition of tumor-progression and increased survival in mice bearing highly malignant human gliomas. We also show that therapeutic hNSC do not proliferate and remain in an un-differentiated state in the brains of glioma-bearing mice. This study provides a platform for accelerated development of future cell-based therapies for cancer.

Journal Article

in vivo imaging; optical imaging; breast cancer; molecular imaging

Optical imaging of breast cancer has been considered for detecting functional and molecular characteristics of diseases in clinical and preclinical settings. Applied to laboratory research, photonic investigations offer a highly versatile tool for preclinical imaging and drug discovery. A particular advantage of the optical method is the availability of multiple spectral bands for performing imaging. Herein, we capitalize on this feature to demonstrate how it is possible to use different wavelengths to offer internal controls and significantly improve the observation accuracy in molecular imaging applications. In particular, we show the independent in vivo detection of cysteine proteases along with tumor permeability and interstitial volume measurements using a dual-wavelength approach. To generate results with a view toward clinically geared studies, a transgenic Her2/neu mouse model that spontaneously developed mammary tumors was used. In vivo findings were validated against conventional ex vivo tests such as histology and Western blot analyses. By correcting for biodistribution parameters, the dual-wavelength method increases the accuracy of molecular observations by separating true molecular target from probe biodistribution. As such, the method is highly appropriate for molecular imaging studies where often probe delivery and target presence are not independently assessed. On the basis of these findings, we propose the dual-wavelength/normalization approach as an essential method for drug discovery and preclinical imaging studies.

Journal Article

Ovarian cancer; Molecular imaging; Intraoperative imaging; Fluorescence imaging

OBJECTIVES: Cytoreductive surgery is a cornerstone of therapy in metastatic ovarian cancer. While conventional white light (WL) inspection detects many obvious tumor foci, careful histologic comparison has shown considerable miss rates for smaller foci. The goal of this study was to compare tumor detection using WL versus near infrared (NIR) imaging with a protease activatable probe, as well as to evaluate the ability to quantify NIR fluorescence using a novel quantitative optical imaging system.

METHODS: A murine model for peritoneal carcinomatosis was generated and metastatic foci were imaged using WL and NIR imaging following the i.v. administration of the protease activatable probe ProSense750. The presence of tumor was confirmed by histology. Additionally, the ability to account for variations in fluorescence signal intensity due to changes in distance between the catheter and target lesion during laparoscopic procedures was evaluated.

RESULTS: NIR imaging with a ProSense750 significantly improved upon the target-to-background ratios (TBRs) of tumor foci in comparison to WL imaging (minimum improvement was approximately 3.5 fold). Based on 52 histologically validated samples, the sensitivity for WL imaging was 69%, while the sensitivity for NIR imaging was 100%. The effects of intraoperative distance changes upon fluorescence intensity were corrected in realtime, resulting in a decrease from 89% to 5% in signal variance during fluorescence laparoscopy.

CONCLUSIONS: With its molecular specificity, low background autofluorescence, high TBRs, and quantitative signal, optical imaging with NIR protease activatable probes greatly improves upon the intraoperative detection of ovarian cancer metastases.