Citation Details

Journal Article

FMT-CT; molecular imaging; atherosclerosis; protease activity; inflammation; in vivo imaging; fluorescence molecular tomography; ProSense

Objective: Proteases are emerging biomarkers of inflammatory diseases. In atherosclerosis, these enzymes are often secreted by inflammatory macrophages, digest the extracellular matrix of the fibrous cap and destabilize atheromata. Protease function can be monitored with protease activatable imaging probes and quantitated in vivo by fluorescence molecular tomography (FMT). To address two major constraints currently associated with imaging of murine atherosclerosis (lack of highly sensitive probes and absence of anatomical information), we compared protease sensors (PS) of variable size and pharmacokinetics and co-registered FMT datasets with computed tomography (FMT-CT).

Methods and results: Co-registration of FMT and CT was achieved with a multimodal imaging cartridge containing fiducial markers detectable by both modalities. A high-resolution CT angiography protocol accurately localized fluorescence to the aortic root of atherosclerotic apoE-/- mice. To identify suitable sensors, we first modeled signal kinetics in-silico and then compared three probes with identical oligo-L-lysine cleavage sequences: PS-5, 5nm in diameter containing 2 fluorochromes , PS-25, a 25nm version with an elongated lysine chain and PS-40, a polymeric nanoparticle. Serial FMT-CT showed fastest kinetics for PS-5 but, surprisingly, highest fluorescence in lesions of the aortic root for PS-40. PS-40 robustly reported therapeutic effects of atorvastatin, corroborated by ex vivo imaging and qPCR for the model protease cathepsin B.

Conclusions: FMT-CT is a robust and observer-independent tool for non-invasive assessment of inflammatory murine atherosclerosis. Reporter-containing nanomaterials may have unique advantages over small molecule agents for in vivo imaging.

Journal Article

In vivo imaging; inflammation; leukocytes; rejection; transplantation; fluorescence molecular tomography; FMT; Prosense

Background: Clinical detection of transplant rejection by repeated endomyocardial biopsy requires catheterization and entails risks. Recently developed molecular and cellular imaging techniques that visualize macrophage host responses could provide a noninvasive alternative. Yet, which macrophage functions may provide useful markers for detecting parenchymal rejection remains uncertain.

Methods and Results: We transplanted isografts from B6 mice and allografts from Balb/c mice heterotopically into B6 recipients. In this allograft across major histocompatability barriers, the transplanted heart undergoes predictable progressive rejection, leading to graft failure after 1 week. During rejection, crucial macrophage functions, including phagocytosis and release of proteases, render these abundant innate immune cells attractive imaging targets. Two or 6 days after transplantation, we injected either a fluorescent protease sensor or a magnetofluorescent phagocytosis marker. Histological and flow cytometric analyses established that macrophages function as the major cellular signal source. In vivo, we obtained a 3-dimensional functional map of macrophages showing higher phagocytic uptake of magnetofluorescent nanoparticles during rejection using magnetic resonance imaging and higher protease activity in allografts than in isografts using tomographic fluorescence. We further assessed the sensitivity of imaging to detect the degree of rejection. In vivo imaging of macrophage response correlated closely with gradually increasing allograft rejection and attenuated rejection in recipients with a genetically impaired immune response resulting from a deficiency in recombinase-1 (RAG-1-/-).

Conclusions: Molecular imaging reporters of either phagocytosis or protease activity can detect cardiac allograft rejection noninvasively, promise to enhance the search for novel tolerance-inducing strategies, and have translational potential.

Journal Article

In vivo imaging; fluorescence molecular tomography; FMT; ProSense; OsteoSense; atherosclerosis; molecular imaging; optical, fluorescence; multimodality; nanoparticle

Imaging approaches that visualize molecular targets rather than anatomic structures aim to illuminate vital molecular and cellular aspects of atherosclerosis biology in vivo. Several such molecular imaging strategies stand ready for rapid clinical application. This review describes the growing role of in vivo optical molecular imaging in atherosclerosis and highlights its ability to visualize atheroma inflammation, calcification, and angiogenesis. In addition, we discuss advances in multimodality probes, both in the context of multimodal imaging as well as multifunctional, or “theranostic,” nanoparticles. This review highlights particular molecular imaging strategies that possess strong potential for clinical translation.

Journal Article

In vivo imaging; MMPSense

An extract of the first 250 words of the full text is provided, because this article has no abstract:

Formation of unstable atherosclerotic plaque in the internal carotid artery carries a high risk for emboli and subsequent cerebral ischemic events. The fibrous cap of such a plaque may become thin and rupture as a result of the depletion of matrix components through the activation of proteolytic enzymes such as matrix-degrading proteinases. Enhanced matrix breakdown has been attributed primarily to a family of matrix-degrading metalloproteinases (MMPs) that are highly concentrated in atherosclerotic plaques by inflammatory cells (eg, macrophages, foam cells), smooth muscle cells and endothelial cells.

Elevated serum MMP-9 concentration is associated with carotid plaque instability and the presence of infiltrated macrophages. Furthermore, analysis of the presence of MMP-9 protein by ELISA within excised carotid plaques revealed high MMP-9 protein mass in calcified segments at or near the carotid bifurcation and in segments with intraplaque hemorrhage. Gelatin zymography showed an increased gelatinase activity of MMP-9 in these segments. These data favor the important role of MMP-9 in the pathogenesis of plaque instability. We analyzed the topographic distribution of MMPs within an excised human carotid plaque by applying multispectral near-infrared fluorescence (NIRF) imaging (IVIS Spectrum, Caliper Life Sciences, Hopkinton, Mass).

A surgical endarterectomy was performed on a 74-year-old women with a left-sided, symptomatic, >70% carotid stenosis. Immediately after endarterectomy, the plaque was placed in PBS and transported to the NIRF system. The plaque was then stretched out and fixed on a silicon plate with 25G needles. A PBS NIRF image was generated from both the intraluminal and extraluminal side of the . . .

Journal Article

In vivo imaging; AngioSense

Extract:

With the advent of tissue regeneration and gene therapy for heart disease, evaluation of coronary circulation and cardiac function in vivo, especially in a disease model, is extremely important. Conventional methods such as microcomputed tomography, high-resolution magnetic resonance angiography, and high-resolution ultrasound have become invaluable tools in cardiovascular research. However, the disadvantages and limitations of these approaches sometimes preclude researchers from conducting important and specific studies on coronary circulation and cardiac function. Therefore, we developed and applied a novel real-time, in vivo fluorescent optical imaging system for use in the mouse cardiovascular system. We report the use of this system for repeatedly assessing coronary circulation, cardiovascular structure, and cardiac function in live mice...