FMT-CT imaging of MMP and protease activity.

<p>(<b>A</b>) Representative images from sham and JVL mice show no visible signal from FMT imaging. (<b>B</b>) Quantification of the fluorescence signal demonstrates barely measurable signal and no significant difference between sham and JVL mice.</p

Histopathology of sham (top row), JVL, (middle row), and EAE (bottom row) groups.

<p>(<b>A</b>) MPO stain for MPO-positive cells/myeloid cells, (<b>B</b>) Mac-3 stain for activated macrophages/microglia, and (<b>C</b>) LFB stain for demyelination. Bar = 50 µm.</p

Weights of sham group (n = 6, open circle) and JVL group (n = 16, solid square) up to day 130 post-surgery.

<p>Weights of sham group (n = 6, open circle) and JVL group (n = 16, solid square) up to day 130 post-surgery.</p

Flow cytometric analysis of brain inflammatory cells.

<p>(<b>A</b>) Cells were pre-gated for positive CD45 expression to identify all leukocytes, and (<b>B</b>) then divided into lymphocytes, neutrophils, and myeloid cells. The total number of all leukocytes, but also lymphocytes, neutrophils, and myeloid cells in the brain was unaffected in JVL mice (n = 4) compared to sham (n = 4), but significantly increased in EAE mice (n = 5). (<b>C</b>) Differentiating macrophages/microglia from monocytes showed that there were almost no monocytes in the brain of JVL and sham mice, but both cell types were increased to high numbers in EAE mice. Lin = CD90, NK1.1, B220, CD49b, and Ly-6G.</p

Use of ¹⁸F‑2-Fluorodeoxyglucose to Label Antibody Fragments for Immuno-Positron Emission Tomography of Pancreatic Cancer

We generated ¹⁸F-labeled antibody fragments for positron emission tomography (PET) imaging using a sortase-mediated reaction to install a <i>trans</i>-cyclooctene-functionalized short peptide onto proteins of interest, followed by reaction with a tetrazine-labeled-¹⁸F-2-deoxyfluoroglucose (FDG). The method is rapid, robust, and site-specific (radiochemical yields > 25%, not decay corrected). The availability of ¹⁸F-2-deoxyfluoroglucose avoids the need for more complicated chemistries used to generate carbon–fluorine bonds. We demonstrate the utility of the method by detecting heterotopic pancreatic tumors in mice by PET, using anti-Class II MHC single domain antibodies. We correlate macroscopic PET images with microscopic two-photon visualization of the tumor. Our approach provides easy access to ¹⁸F-labeled antibodies and their fragments at a level of molecular specificity that complements conventional ¹⁸F-FDG imaging

Use of ¹⁸F‑2-Fluorodeoxyglucose to Label Antibody Fragments for Immuno-Positron Emission Tomography of Pancreatic Cancer

We generated ¹⁸F-labeled antibody fragments for positron emission tomography (PET) imaging using a sortase-mediated reaction to install a <i>trans</i>-cyclooctene-functionalized short peptide onto proteins of interest, followed by reaction with a tetrazine-labeled-¹⁸F-2-deoxyfluoroglucose (FDG). The method is rapid, robust, and site-specific (radiochemical yields > 25%, not decay corrected). The availability of ¹⁸F-2-deoxyfluoroglucose avoids the need for more complicated chemistries used to generate carbon–fluorine bonds. We demonstrate the utility of the method by detecting heterotopic pancreatic tumors in mice by PET, using anti-Class II MHC single domain antibodies. We correlate macroscopic PET images with microscopic two-photon visualization of the tumor. Our approach provides easy access to ¹⁸F-labeled antibodies and their fragments at a level of molecular specificity that complements conventional ¹⁸F-FDG imaging

Use of ¹⁸F‑2-Fluorodeoxyglucose to Label Antibody Fragments for Immuno-Positron Emission Tomography of Pancreatic Cancer

We generated ¹⁸F-labeled antibody fragments for positron emission tomography (PET) imaging using a sortase-mediated reaction to install a <i>trans</i>-cyclooctene-functionalized short peptide onto proteins of interest, followed by reaction with a tetrazine-labeled-¹⁸F-2-deoxyfluoroglucose (FDG). The method is rapid, robust, and site-specific (radiochemical yields > 25%, not decay corrected). The availability of ¹⁸F-2-deoxyfluoroglucose avoids the need for more complicated chemistries used to generate carbon–fluorine bonds. We demonstrate the utility of the method by detecting heterotopic pancreatic tumors in mice by PET, using anti-Class II MHC single domain antibodies. We correlate macroscopic PET images with microscopic two-photon visualization of the tumor. Our approach provides easy access to ¹⁸F-labeled antibodies and their fragments at a level of molecular specificity that complements conventional ¹⁸F-FDG imaging

Tracking Mesenchymal Stem Cells with Iron Oxide Nanoparticle Loaded Poly(lactide-co-glycolide) Microparticles

Monitoring the location, distribution and long-term engraftment of administered cells is critical for demonstrating the success of a cell therapy. Among available imaging-based cell tracking tools, magnetic resonance imaging (MRI) is advantageous due to its noninvasiveness, deep penetration, and high spatial resolution. While tracking cells in preclinical models via internalized MRI contrast agents (iron oxide nanoparticles, IO-NPs) is a widely used method, IO-NPs suffer from low iron content per particle, low uptake in nonphagocytotic cell types (e.g., mesenchymal stem cells, MSCs), weak negative contrast, and decreased MRI signal due to cell proliferation and cellular exocytosis. Herein, we demonstrate that internalization of IO-NP (10 nm) loaded biodegradable poly­(lactide-co-glycolide) microparticles (IO/PLGA-MPs, 0.4–3 μm) in MSCs enhances MR parameters such as the <i>r</i>₂ relaxivity (5-fold), residence time inside the cells (3-fold) and <i>R</i>₂ signal (2-fold) compared to IO-NPs alone. Intriguingly, in vitro and in vivo experiments demonstrate that internalization of IO/PLGA-MPs in MSCs does not compromise inherent cell properties such as viability, proliferation, migration and their ability to home to sites of inflammation