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Lecture 24 BIOE 498/598 DP 04/30/2014
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Lecture 24 BIOE 498/598 DP 04/30/2014

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  1. Lecture 24BIOE 498/598 DP04/30/2014

  2. NSF and Why Gd Should be Avoided NSF lawsuit advertisement Issues Toxicity: Recent discovery of NSF associated with Gd based MRI agents BOXED WARNING: NEPHROGENIC SYSTEMIC FIBROSIS (NSF) Gadolinium-based contrast agents increase the risk for nephrogenic systemic fibrosis (NSF) in patients with: • Acute or chronic severe renal insufficiency (glomerular filtration rate <30mL/min/1.73m2) or • Acute renal insufficiency of any severity due to the hepato-renal syndrome or in the perioperative liver transplantation period. Patient with NSF

  3. MRI Agents Based on Non-lanthanides Lanthanide gadolinium is NOT safe: Linked to Nephrogenic Systemic Fibrosis (NSF) • Promise • Fe(III), Mn(II), Mn(III), Cu(II) • Favorable biochemistry • Limitation • Sensitivity • Lack of suitable nano platforms • Safety • Solution • Nano-engineering approach • Safe • Efficient • Commercially amenable Metals in the form of organometallics /organically soluble complexes and NP No metals on the surface as contrary to commonly pursued approaches, 80-200nm • Pre-requisites:Bio-metabolizablenanoparticle with at least 100,000 metal/NP with specificity in the nanomolar range. Pan et. al. J Am Chem Soc. 2008 Jul 23;130(29):9186-7. Pan et. al. Chem Commun (Camb). 2009, 22, 3234-6.

  4. Mn Based T1w MR Contrast Agents ManOC ManOC MRI 10 nm ManOL Thermal decomposition ManOL Relaxivities /(s.mmol)_1 A unique way of incorporating heavy payload of metal Average metal /NP = 120,000 Pan et. al, Chemical Communications, 2009, 3234 - 3236

  5. Metal NanoColloids for T1-weighted MRI MR properties are presumably not dependent on the interaction of M with surrounding water! T1w MRI Strong T2 effects Weaker T2 effects Metal Nanoparticle Metal Nanocolloids Fe-Nanocolloids (a) (b) T2*/T2 T1 <T2 Mn(II)-Nanocolloids Metal Cu(II)-Nanocolloids B0 B0 External Magnetic field External Magnetic field Cartoon illustrating hypothesis of decreased T2* effects (a) A typical metal particle surrounded by water within a B0 field. The field dependent dipole moment created is shown. Protons pass deep within this magnetic flux field and experience strong dephasing T2 effects. (b). The encapsulation of metal crystals reduces the effective field experienced by the surrounding protons, such that the relative impact on T2* is greater than the changes of T1 relaxivity. Chem Commun, 2009; ACS Nano 2009; JACS 2011

  6. In vitro and ex-vivo Targeted MRI with CION with anti-Fibrin Antibody CION Control Fibrin-rich Plasma Clots CION CION Rapid T1w Imaging Senpan, Caruthers, Pan, Wickline, Lanza, 2009 ACS Nano

  7. In vitro and ex-vivo Targeted MRI with CION with anti-Fibrin Antibody CION Control Fibrin-rich Plasma Clots CION CION Rapid T1w Imaging Senpan, Caruthers, Pan, Wickline, Lanza, 2009 ACS Nano

  8. Copper As MR Contrast Agent MRI detection of fibrin clots in vitro. On T1-weighted cross-sectional images, the clot with Targeted NanoQ (A) shows marked signal enhancement, whereas the controls of Non-Targeted Contrast Agent (B) or No Treatment (C) show little or no enhancement above the background water signal. (D) Normalized contrast-to-noise measurements of targeted and control NanoQ bound to clots with respect to the surrounding fluid. J. Am. Chem. Soc., 2011, 133 (24), pp 9168–9171

  9. Pharmacokinetics and Biodistribution in Rats C(t)=Ae-αt + Be-βt with constants A and α describing the distribution phase, and B and β describing the blood clearance phase.The half-life for the distribution phase was 5.04 ± 1.1 min; elimination half-life was 99.2 ± 10.7 min. Copper organocomplexes were rapidly bio-eliminated primarily through both renal and biliary routes, suggested by the metal concentrations of the kidney and feces ICP-OES analyses of blood and organs for Cu In vivo pharmacokinetics and bio-distribution of NanoQ. (A) pharmacokinetic profile of targeted NanoQ with a bi-exponential fitting (y=0.5903*exp(-0.1374*t) + 0.5205*exp(-0.0070*t). (B) Organ distribution of NanoQ based on copper estimation of major organs by ICP-OES at 2h following NanoQ injection (1mg/ml) i.v.

  10. Dual Modality Optical-MRI Imaging of Integrin a) Schematic illustration of dual-modality RGD targeted iron oxide nanoparticles containing IRDye800 for tumor ανβ3integrin imaging. b) TEM of the 10 nm iron oxide nanoparticles. c) T2-weighted phantom images of targeted agent at increased iron concentrations. d) 1/T2 vs. Fe concentration plot of the targeted agent.

  11. a) MR images of U87MG tumor-bearing mice injected with the RGD targeted dual agent (RGD-TPIO) and the non-targeted agent (TPIO) at a dose of 10 mg Fe/kg. The images were taken both coronally and transversely before and 4 h after particle injection. b) Optical imaging of U87MG tumor-bearing mice injected with RGD-TPIO and TPIO. The images were acquired 4 h hh h post injection. http://www.thno.org/v01p0083.htm

  12. Dual Modality Optical-MRI Imaging of Integrin Schematic representation of the synthesis of QDs with a paramagnetic micellar coating. QDs and lipids in chloroform are slowly infused in hot water that, via chloroform-in-water emulsions, swiftly form micelles when chloroform evaporates, some of which have a Qdot core. In vitro targeting and imaging with QD-micelles. a, left T1-weighted MRI image of cells that were incubated with RGD-pQDs, pQDS, or without contrast agent. a, right Fluorescence microscopy of HUVEC incubated with RGD-pQDs. 

  13. Dual Modality Optical-MRI Imaging of Integrin The schematic structure of αvβ3-integrin targeted micellar nanoparticles for optical and MR imaging (left) and MR and optical molecular imaging of tumor angiogenesis (right). T2-weighted images before the contrast agent was injected (a, e); T1-weighted images before (b, f) and 45 min after (c, g) the injection of the RGD targeted micellar imaging agent and color-coded signal enhancement in tumors (d, h). The arrows in (c, g) indicate bright regions in the periphery of the tumor. Bioluminescence image (i) and fluorescence image (j) of a nude mouse with a luciferase-expressing renal carcinoma tumor after injection of luciferin (i) and the targeted imaging agent (j). The signal colocalizes with a strong fluorescence signal (j) originating from intravenously administrated RGD-pQDs that are accumulated in the tumor.

  14. β-galactosidase Enzyme-mediatedcontrast agent CLIO Ca2+mediatedcontrast agent Gen-sequencespecificcontrast agent (also for Zn2+ en pH) Molecular Imaging with Smart Contrast Agents H2O T « Switch-on / switch-off » probes Liposome membrane Temperature sensitive contrast agent

  15. 19F MRI • The19F nucleus has a 100% natural abundance Resonates at a resonant frequency that is 94% of that of 1H. • NMR sensitivity is 83% of that of 1H (with constant noise) • MRI signal-to-noise ratio (SNR) is about 89% of 1H per nucleus, assuming sample-dominant noise (i.e. the noise increases linearly with frequency). • Negligible endogenous 19F MRI signal from the body, as the physiological concentrations of detectable mobile fluorine are below the detection limit (usually less than 10−3μmol/g wet tissue weight). • Fluorine exists at higher concentrations in the bone matrix and teeth, but, being immobilized, exhibits a very short spin–spin relaxation time (T2) that is not visible to conventional MRI methods. 

  16. List of 19F drugs and therapeutic agents

  17. NMR Biomed. Feb 2011; 24(2): 114–129.

  18. Live Cell Imaging Infiltration of perfluorocarbons (PFCs) after myocardial infarction as detected by in vivo19F MRI. (a) Anatomically corresponding 1H and 19F images from the mouse thorax recorded 4 days after ligation of the left anterior descending coronary artery, showing accumulation of 19F signal near the infarcted region (I) and at the location of surgery where the thorax was opened (T). PFCs were injected at day 0 (2 h after infarction) via the tail vein. (b) Sections of 1H images superimposed with the matching 19F images (red) acquired 1, 3 and 6 days after surgery (post OP) indicate a time-dependent infiltration of PFCs into injured areas of the heart and the adjacent region of the chest affected by thoracotomy. At day 4, an additional bolus of PFCs was injected to compensate for clearance of the particles from the bloodstream after 3 days.

  19. In vivo19F MRI of perfluoro-crown ether (PFCE)-labeled dendritic cells in a mouse. (a) Mouse quadriceps after intramuscular injection of PFCE-labeled cells. From left to right are 19F, 1H and a composite 19F/1H image. (b) Composite image of dendritic cell migration into the popliteal lymph node following a hind foot pad injection. (c) Composite image through the torso following intravenous inoculation with perfluoropolyether (PFPE)-labeled cells. Cells are apparent in the liver (L), spleen (S) and, sporadically, lungs (Lu). Electron micrograph of a labeled fetal skin-derived dendritic cell line at a low magnification (d) and a higher magnification (e). Particles (100–200 nm) appear as smooth spheroids. Arrows show a typical multiple-membrane compartment enclosing these particles.

  20. Stem Cell Tracking Localization of labeled cells after in situ injection. (a) To determine the utility for cell tracking stem/progenitor cells labeled with either perfluoro-octyl bromide (PFOB) (green) or perfluoro-crown ether (PFCE) (red), nanoparticles were locally injected into mouse thigh skeletal muscle. (b–d) At 11.7 T, spectral discrimination permits the imaging of the fluorine signal attributable to ~ 1 × 106 PFOB-loaded (b) or PFCE-loaded (c) cells individually which, when overlaid onto a conventional 1H image of the site (d), reveals PFOB- and PFCE-labeled cells localized to the left and right leg, respectively (broken line indicates 3 × 3-cm2 field of view for 19F images). (e, f) Similarly, at 1.5 T, 19F image of ~ 4 × 106 PFCE-loaded cells (e) locates to the mouse thigh in a 1H image of the mouse cross-section (f). The absence of background signal in 19F images (b, c, e) enables unambiguous localization of PFCE-containing cells at both 11.7 and 1.5 T. 

  21. Neural Stem Cells In vivo MRI of transplanted C17.2 neural stem cells, with the 19F signal superimposed on the 1H MR images. (a–c) MR images at 1 h (a), 3 days (b) and 7 days after injection of 4 × 104 (left hemisphere, arrowhead in a) or 3 × 105 (right hemisphere, arrow in a) cationic perfluoro-crown ether (PFCE)-labeled cells. (e, f) Corresponding histopathology at day 7 with phase contrast (e) and anti-β-gal immunohistochemistry (f) demonstrates that implanted cells remain viable and continue to produce the marker enzyme. In (f), the right arrow indicates cells migrating from the injection site into the brain parenchyma. (d) MR image of a different animal at 14 days after injection of equal amounts of 4 × 105 C17.2 cells in both hemispheres, demonstrating the persistence of the 19F signal for 2 weeks. (g) Corresponding histopathology showing rhodamine fluorescence from PFCE-labeled cells co-localizing with the 19F signal. Scale bar, 500 μm. 

  22. CEST Agents

  23. Angiography by TOF-MRA is a form of saturation transfer experiment. An image slice, represented by the dotted line, is acquired by saturating the bulk water protons only in that image slice (left, the saturation is represented in blue). After a short time delay, the saturation of water protons in blood has been transferred out of the slice and replaced by unsaturated spins (middle). Thus, when the image is acquired, the stationary tissue appears dark but the blood is bright. In this way, angiograms may be acquired, such as the one of the carotid arteries shown (right).

  24. Schematic representations of the distribution of spins, aligned with and against the field (upper and lower energy levels, respectively) (above) and simulated NMR spectra (below) for two chemically distinct pools of nuclei (left), two spins after a saturation pulse has been applied to one pool (middle), and for a system undergoing chemical exchange after a saturation pulse has been applied to one pool (right).