Characterization of lung cancer by amide proton transfer (APT) imaging: an in-vivo study in an orthotopic mouse model.

Amide proton transfer (APT) imaging is one of the chemical exchange saturation transfer (CEST) imaging methods which images the exchange between protons of free tissue water and the amide groups (-NH) of endogenous mobile proteins and peptides. Previous work suggested the ability of APT imaging for characterization of the tumoral grade in the brain tumor. In this study, we tested the feasibility of in-vivo APT imaging of lung tumor and investigated whether the method could differentiate the tumoral types on orthotopic tumor xenografts from two malignant lung cancer cell lines. The results revealed that APT imaging is feasible to quantify lung tumors in the moving lung. The measured APT effect was higher in the tumor which exhibited more active proliferation than the other. The present study demonstrates that APT imaging has the potential to provide a characterization test to differentiate types or grade of lung cancer noninvasively, which may eventually reduce the need invasive needle biopsy or resection for lung cancer

Inflammation Modulates Murine Venous Thrombosis Resolution In Vivo: Assessment by Multimodal Fluorescence Molecular Imaging

Objective: Assessment of thrombus inflammation in vivo could provide new insights into deep vein thrombosis (DVT) resolution. Here we develop and evaluate two integrated fluorescence molecular-structural imaging strategies to quantify DVT-related inflammation and architecture, and to assess the effect of thrombus inflammation on subsequent DVT resolution in vivo. Methods and Results: Murine DVT were created with topical 5% FeCl3 application to thigh or jugular veins (n=35). On day 3, mice received macrophage and matrix metalloproteinase (MMP) activity fluorescence imaging agents. On day 4, integrated assessment of DVT inflammation and architecture was performed using confocal fluorescence intravital microscopy (IVM). Day 4 analyses showed robust relationships among in vivo thrombus macrophages, MMP activity, and FITC-dextran deposition (r \u3e 0.70, p \u3c 0.01). In a serial two-timepoint study, mice with DVT underwent IVM at day 4 and at day 6. Analyses revealed that the intensity of thrombus inflammation at day 4 predicted the magnitude of DVT resolution at day 6 (p \u3c 0.05). In a second approach, noninvasive fluorescence molecular tomography-computed tomography (FMT-CT) was employed, and detected macrophages within jugular DVT (p \u3c 0.05 vs. sham-controls). Conclusions: Integrated fluorescence molecular-structural imaging demonstrates that the DVT-induced inflammatory response can be readily assessed in vivo, and can inform the magnitude of thrombus resolution

Statins Improve the Resolution of Established Murine Venous Thrombosis: Reductions in Thrombus Burden and Vein Wall Scarring

Despite anticoagulation therapy, up to one-half of patients with deep vein thrombosis (DVT) will develop the post-thrombotic syndrome (PTS). Improving the long-term outcome of DVT patients at risk for PTS will therefore require new approaches. Here we investigate the effects of statins—lipid-lowering agents with anti-thrombotic and anti-inflammatory properties—in decreasing thrombus burden and decreasing vein wall injury, mediators of PTS, in established murine stasis and non-stasis chemical-induced venous thrombosis (N = 282 mice). Treatment of mice with daily atorvastatin or rosuvastatin significantly reduced stasis venous thrombus burden by 25% without affecting lipid levels, blood coagulation parameters, or blood cell counts. Statin-driven reductions in VT burden (thrombus mass for stasis thrombi, intravital microscopy thrombus area for non-stasis thrombi) compared similarly to the therapeutic anticoagulant effects of low molecular weight heparin. Blood from statin-treated mice showed significant reductions in platelet aggregation and clot stability. Statins additionally reduced thrombus plasminogen activator inhibitor-1 (PAI-1), tissue factor, neutrophils, myeloperoxidase, neutrophil extracellular traps (NETs), and macrophages, and these effects were most notable in the earlier timepoints after DVT formation. In addition, statins reduced DVT-induced vein wall scarring by 50% durably up to day 21 in stasis VT, as shown by polarized light microscopy of picrosirius red-stained vein wall collagen. The overall results demonstrate that statins improve VT resolution via profibrinolytic, anticoagulant, antiplatelet, and anti-vein wall scarring effects. Statins may therefore offer a new pharmacotherapeutic approach to improve DVT resolution and to reduce the post-thrombotic syndrome, particularly in subjects who are ineligible for anticoagulation therapy

Analyses for Z-spectrum and MTR_asym of both types of lung tumors.

<p>Z-spectra of A549 (<b>A</b>) and LLC (<b>B</b>) tumors compared to that of spinal cord as a reference show that the LLC tumor has a larger CEST effect than A549 tumor. Corrected MTR_asym spectra of A549 and LLC (<b>C</b>) and corrected MTR_asym at 3.5 ppm (<b>D</b>) show that LLC has a larger APT effect than A549, which may be related to the malignancy of the tumors. *, <i>P</i>≤0.05; **, P≤0.01; ***, P≤0.001 by Student’s t-test.</p

In-vivo APT imaging of lung tumors in the orthotopic mouse model.

<p>Representative T2-weighted images (left) and APT-weighted images (right, MTR_asym map at 3.5 ppm) of A549 (<b>A</b>) and LLC (<b>B</b>) where the tumors (open arrows) are delineated brighter than the surrounding tissues including spinal cord (closed arrows) and skeletal muscles. A typical region of interest to measure signal intensity on a tumor is demonstrated (<b>B</b>).</p

Study design for APT imaging of the mice lung using the small animal ventilator.

<p>The animal was mechanically ventilated for constant amplitude and frequency of respiration at 32 breaths/min in which inhalation and end-expiration was 0.2 s and 1.6 s, respectively. The lung was inflated until the intrapulmonary pressure becomes 20 cm H₂O. Fast spin-echo images were obtained following a presaturation pulse (continuous-wave block pulse, B1 = 1.7 µT, duration = 4 s) in the end-expiratory phase.</p

Micrographs of the A549 tumor and LCC tumor.

<p>Hematoxylin-eosin staining (original magnification×400) demonstrates that LCC (<b>C</b>) have higher cell density and larger cell nuclei compared to A549 (<b>A</b>). Ki-67 staining (original magnification×200) reveals larger fraction of positive cells seen in LCC (<b>D</b>) than in A549 (<b>B</b>). This indicates the presence of a larger number of cells in active phases of the cell cycle (G₁, S, G₂, and mitosis) and thus the aggressive nature of LCC.</p