Name: synthesis, characterization, and application of superparamagnetic iron oxide nanoprobes for extrapulmonary tuberculosis detection
Uploaded: 2020-02-16T12:00:00
Description: Watch this Scientific Journal Video about Synthesis, Characterization, and Application of Superparamagnetic Iron Oxide Nanoprobes for Extrapulmonary Tuberculosis Detection at JoVE.com

The authors are thankful for the financial support from the Ministry of Economy Taiwan (grants NSC-101-2120-M-038-001, MOST 104-2622-B-038 -007, MOST 105-2622-B-038-004) to perform this research work. This manuscript was edited by Wallace Academic Editing.

All protocol regarding animal experiment follows the standard operating procedures for laboratory animal breeding in accordance with the National Institutes of Health Guidelines for the Care and Use of Laboratory Animals (8th Edition, 2011) and is approved by the institutional animal care and use committee.
1. SPIO nanoparticle synthesis
<ol>
	<li>Prepare dextran-coated iron oxide magnetic nanoparticles by vigorously stirring a mixture of dextran T-40 (5 mL; 50% w/w) and aqueous FeCl3</...

<ol>
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E., Ellis, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Laboratory Histopathology- A Complete Reference. 1st edn. , 6-11 (1994).</li><li>Lee, C. N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Super-paramagnetic+iron+oxide+nanoparticles+for+use+in+extrapulmonary+tuberculosis+diagnosis.">Super-paramagnetic iron oxide nanoparticles for use in extrapulmonary tuberculosis diagnosis.</a> Clinical Microbiology and Infection. 18, 149-157 (2012).</li><li>Lee, H., Yoon, T. 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Similar to relevant studies, our findings regarding SPIO-MtbsAb nanoprobes demonstrated a significant specificity for Mtb27,28. The subcutaneous Mtb granuloma was found 1 month after TB injection in the mouse models. The typical TB granulomatous histology findings included lymphocyte infiltration, presence of epithelioid macrophages, and neovascularization. Acid-fast bacilli were scattered in the TB lesions, corroborating the MtbsAb immunohistochemistry findings....

Globally, extrapulmonary tuberculosis (ETB) represents a significant proportion of tuberculosis (TB) cases. Nevertheless, ETB diagnosis is often missed or delayed because of its insidious clinical presentation and poor performance on diagnostic tests; false results include sputum smears negative for acid-fast bacilli, lack of granulomatous tissue on histopathology, or failure to culture Mycobacterium tuberculosis (Mtb). Relative to typical cases, ETB occurs less frequently and involves little liberation of the Mtb bacilli. In addition, it is usually localized at difficult-to-access sites, such as lymph nodes, pleura, and osteoarticular areas1. Thus, invasive procedures for obtaining adequate clinical specimens, which makes bacteriological confirmation risky and difficult, are essential2,3,4.
Commercially available antibody detection tests for ETB are unreliable for clinical detection because of their wide range of sensitivity (0.00-1.00) and specificity (0.59-1.00) for all extrapulmonary sites combined5. Enzyme-linked immunospot (ELISPOT) assays for interferon-&#947;, culture filtrate protein (CFP), and early secretory antigenic target (ESAT) have been used for diagnosing latent and active TB. However, the results vary between different disease sites for diagnosing ETB6,7,8. In addition, skin PPD (purified protein derivative) and QuantiFERON-TB frequently provided false negative results9. QuantiFERON-TB-2G is a whole blood immune reactivity assay, which does not require a specimen from the affected organ and this may be an alternative diagnostic tool6,10,11. Other diagnostic methods typically used for TB meningitis, such as polymerase chain reaction, are still too insensitive to confidently exclude clinical diagnosis12,13. These conventional tests demonstrate insufficient diagnostic information to discover the extrapulmonary infection site. Thus, novel diagnostic modalities are clinically required.
Molecular imaging aims at designing novel tools that can directly screen specific molecular targets of disease processes in vivo14,15. Superparamagnetic iron oxide (SPIO), a T2-weighted NMR contrast agent, can significantly enhance the specificity and sensitivity of magnetic resonance (MR) imaging (MRI)16,17. This new functional imaging modality can precisely sketch tissue changes at the molecular level through ligand-receptor interactions. In this study, a new molecular imaging probe, comprising SPIO nanoparticles, was synthesized to conjugate with Mtb surface antibody (MtbsAb) for ETB diagnosis. SPIO nanoprobes are minimally invasive to tissues and bodies under examination18,19. Furthermore, these nanoprobes can demonstrate precise MR images at low concentrations due to their paramagnetic properties. In addition, SPIO nanoprobes appear elicit least allergic reactions because the presence of iron ions is part of normal physiology. Here, the sensitivity and specificity of the SPIO-MtbsAb nanoprobes targeting ETB were evaluated in both cell and animal models. The outcomes demonstrated that the nanoprobes were applicable as ultrasensitive imaging agents for ETB diagnosis.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>(benzotriazol-1-yloxy) tripyrrolidinophosphonium hexafluorophosphate</td>
			<td>Sigma-Aldrich</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>1-hydroxybenzotriazole</td>
			<td>Sigma-Aldrich</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>dextran(T-40)</td>
			<td>GE Healthcare Bio-sciences AB</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>epichlorohydrin, 2,2&#39;-(ethylenedioxy)bis(ethylamine)</td>
			<td>Sigma-Aldrich</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>ferric chloride hexahydrate</td>
			<td>Fluka</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>ferrous chloride tetrahydrate</td>
			<td>Fluka</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Human monocytic THP-1</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>M. bovis BCG</td>
			<td>Pasteur M&#233;rieux</td>
			<td>Connaught strain; ImmuCyst Aventis</td>
			<td></td>
		</tr>
		<tr>
			<td>MRI</td>
			<td>GE medical Systems</td>
			<td>3.0-T, Signa</td>
			<td></td>
		</tr>
		<tr>
			<td>NH4OH</td>
			<td>Fluka</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>NMR relaxometer</td>
			<td>Bruker</td>
			<td>NMS-120 Minispec</td>
			<td></td>
		</tr>
		<tr>
			<td>Sephacryl S-300</td>
			<td>GE Healthcare Bio-sciences AB</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sephadex G-25</td>
			<td>GE Healthcare Bio-sciences AB</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>SPECTRUM molecular porous membrane tubing, 12,000 -14,000 MW cut off</td>
			<td>Spectrum Laboratories Inc</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>TB surface antibody- Polyclonal Antibody to Mtb</td>
			<td>Acris Antibodies GmbH</td>
			<td>BP2027</td>
			<td></td>
		</tr>
		<tr>
			<td>transmission electron microscope</td>
			<td>JEOL</td>
			<td>JEM-2000 EX II</td>
			<td></td>
		</tr>
	</tbody>
</table>

synthesis, characterization, and application of superparamagnetic iron oxide nanoprobes for extrapulmonary tuberculosis detection

A molecular imaging probe comprising superparamagnetic iron oxide (SPIO) nanoparticles and Mycobacterium tuberculosis surface antibody (MtbsAb) was synthesized to enhance imaging sensitivity for extrapulmonary tuberculosis (ETB). An SPIO nanoprobe was synthesized and conjugated with MtbsAb. The purified SPIO-MtbsAb nanoprobe was characterized using TEM and NMR. To determine the targeting ability of the probe, SPIO-MtbsAb nanoprobes were incubated with Mtb for in vitro imaging assays and injected into Mtb-inoculated mice for in vivo investigation with magnetic resonance (MR). The contrast enhancement reduction on magnetic resonance imaging (MRI) of Mtb and THP1 cells showed proportional to the SPIO-MtbsAb nanoprobe concentration. After 30 min of intravenous SPIO-MtbsAb nanoprobe injection into Mtb-infected mice, the signal intensity of the granulomatous site was enhanced by 14-fold in the T2-weighted MR images compared with that in mice receiving PBS injection. The MtbsAb nanoprobes can be used as a novel modality for ETB detection.

SPIO-MtbsAb nanoprobe synthesis and characterization 
SPIO nanoparticles were designed to conjugate with MtbsAb. The dextran stabilized on the surface of SPIO nanoparticles was crosslinked by epichlorohydrin. SPIO nanoparticles were subsequently incorporated with EDBE to activate primary amine functional groups at the dextran ends. SA was then conjugated to form SPIO-EDBE-SA. SPIO-MtbsAb nanoprobes formed in the final step through the conjugation of MtbsAb with SPIO-EDBE-SA in the presence of the co...

Watch this Scientific Journal Video about Synthesis, Characterization, and Application of Superparamagnetic Iron Oxide Nanoprobes for Extrapulmonary Tuberculosis Detection at JoVE.com

Synthesis, Characterization, and Application of Superparamagnetic Iron Oxide Nanoprobes for Extrapulmonary Tuberculosis Detection

To improve serological diagnostic tests for Mycobacterium tuberculosis antigens, we developed superparamagnetic iron oxide nanoprobes to detect extrapulmonary tuberculosis.

A molecular imaging probe comprising superparamagnetic iron oxide (SPIO) nanoparticles and Mycobacterium tuberculosis surface antibody (MtbsAb) was ...

Globally, extrapulmonary tuberculosis diagnosis is often delayed, as it requires a surgical intervention for confirmation due to non-specific clinical presentation and a poor performance on diagnostic tests. To improve serological diagnostic tests for Mycobacterium tuberculosis antigens, we have developed super-paramagnetic iron oxide nanoprobes for detecting extrapulmonary tuberculosis. TB-SPIO nanoprobes can provide precise magnetic resonance images at low concentrations due to their paramagnetic properties without inducing any autoimmune response.TB-SPIO nanoprobes enable the targeting and detection of Mycobacterium tuberculosis infection. They can also be applied as MRI contrast agent for the detection of other diseases. Be sure to study the protocol carefully before attempting the protocol, as each part of the experiment utilizes a specific core technology.Visual demonstrate of the method can help pupils to understand how to implement the process, especially for some of the more complicated experiments. To prepare dextran-coated iron oxide magnetic nanoparticles, vigorously combine five milliliters of dextran T40 with 45 milligrams aqueous ferric chloride hexahydrate and 32 milligrams of of ferrous chloride tetrahydrate solutions at room temperature. Rapidly add 10 milliliters of ammonium hydroxide and use a stir bar to stir the resulting black suspension for one hour at room temperature.At the end of the stirring incubation, centrifuge the solution and remove the aggregates. To separate the final SPIO products from the the unbound dextran T40, load the entire five-milliliter reaction mixture into a 2.5 by 33-centimeter gel filtration chromatography column and elute the dextran with 0.1-molar of sodium acetate and 0.15-molar of sodium chloride buffer solution. Then, collect the purified dextran-coated iron oxide magnetic nanoparticles in the void volume and assay the column eluates for iron and dextran at 330 and 490 nanometers according to standard protocols.To create SPIO-conjugated Mycobacterium tuberculosis surface antibodies, first synthesize SPIO-EDBE-succinic anhydride by mixing 10 milliliters of an alkaline solution of SPIO-EBDE with one gram of succinic anhydride for 24 hours at room temperature. The next day, use 12, 000 to 4, 000 molecular weight cutoff molecular porous membrane tubing to dialyze the solution with 26-hour changes of two liters of distilled water per change. After the last change, add 100 microliters of the resulting solution to 400 microliters of 4.5 milligrams per milliliters TB surface antibody, followed by the addition of 1-hydroxybenzotriazole and benzotriazol-1-yloxy tripyrrolidinophosphonium hexafluorophosphate as catalysts at room temperature for 24 hours with stirring.Separate the solutions from the unbound antibody through gel filtration chromatography using PBS as the buffer. To determine the average particle size, morphology, and size distribution, drop-cast the composite dispersion onto a 200-mesh copper grid and air-dry the sample at room temperature before loading onto a transmission electron microscope for imaging at 100 kilovolts. To measure the relaxation time values of the nanoprobes, use a nuclear magnetic resonance relaxometer at 20 megahertz and 37 degrees Celsius plus or minus one degree.For nanoprobe pulsed cell imaging, first cultivate human THP-1 monocytes according to standard cell culture protocols. When the cells have reached the appropriate stage of activation, preincubate one times 10 to the seven monocytes with one times 10 to the sixth colony-forming units of Mycobacterium bovis BCG for one hour. At the end of the incubation, transfer the cells to one-milliliter microcentrifuge tubes and add two millimolar of SPIO Mycobacterium tuberculosis surface antibody-conjugated nanoprobes to each tube for a one-hour incubation at 37 degrees Celsius and 5%carbon dioxide.At the end of the incubation, collect the cells by centrifugation and resuspend the pellets in 200 microliters of fresh medium. Then, scan the samples using a fast gradient echo pulse sequence through 3.0-T magnetic resonance imaging to determine the specificity and sensitivity of the nanoprobes. To inoculate experimental animals with M.bovis BCG, first reconstitute the lyophilized vaccine or bacterial stock in Sauton's medium and dilute the reconstituted stock solution with saline.Next, load 100 microliters of the solution into one one-milliliter syringe per animal and inject the entire volume of bacteria intradermally into the left or right dorsal scapular skin of each mouse. For in vivo magnetic resonance imaging of live nanoprobe-injected animals, acquire baseline T2-weighted fast spin-echo images of each anesthetized experimental animal before injecting two nanomolar of SPIO-TB antibody probes suspended into 200 microliters of saline into the tail vein of each mouse. Then, image the animals again immediately after the injection and every five minutes for the next 30 minutes.At the end of the imaging session, quantitatively analyze all of the magnetic resonance images using the signal intensity as a measurement of the defined regions of interest in comparable locations of an M.tuberculosis granuloma center and the back muscle adjacent to a granulomatis area. Then, use the formula to calculate the relative signal enhancements using the signal intensity measurement before and zero to three hours after the injection of the contrast agents. One month after inoculation, collect the tissue from the intradermal inoculation site of each animal and stain the formalin-fixed paraffin-embedded five to 10-micrometer thick tissue samples with hematoxylin and eosin, Ziehl-Neelsen stains for acid-fast bacteria, and Berlin blue for ferric iron.Transmission electron microscopy imaging of SPIO-TB surface antibody nanoprobes reveals that the nanoprobes exhibit a well-dispersed appearance with an average size of 3.8 plus or minus 0.4 nanometers per core. M.bovis BCG and acid-fast bacterial strain can be detected through Ziehl-Neelsen staining. After isolation and culture with probes containing ferric iron, the bacteria can be identified through Berlin blue staining.The TB-targeting degree of SPIO-TB surface antibody nanoprobes can be determined through T2-weighted magnetic resonance imaging as indicated by a decrease in the signal intensity in the presence of the nanoprobes that occurs in a concentration dependent manner. In nanoprobe-injected animals, the T2-weighted enhancement of signal reduction in the M.tuberculosis granulomatis areas is approximately 14-fold higher than that of the control sites. One month after infection, an organized subcutaneous granuloma can be observed in nanoprobe-injected C57 black 6 mice with new blood vascularization and lymphocyte and epithelioid macrophage aggregates noted within these lesions.Positive M.tuberculosis expression is also observed in the granulomatous areas with acid-fast bacilli staining positive at the lesion site. Berlin blue, a ferric iron positive stain, can also be used to determine the sensitivity of the probes to TB.For in vivo magnetic resonance image of life, nanoprobe-injected animals acquire baseline T2-weighted fast spin-echo image of each anesthetized experimental animal before injecting the SPIO-TB antibody probes. Now that we have established the SOP technique to detect extrapulmonary tuberculosis, these antibodies can be used to specifically diagnose extrapulmonary tuberculosis.

synthesis-characterization-application-superparamagnetic-iron-oxide

Research

JoVE Journal

Medicine

Production and Detection of Reactive Oxygen Species (ROS) in Cancers

Reactive oxygen species include a number of molecules that damage DNA and RNA and oxidize proteins and lipids (lipid peroxydation). These reactive molecules contain an oxygen and include H2O2 (hydrogen peroxide), NO (nitric oxide), O2- (oxide anion), peroxynitrite (ONOO-), hydrochlorous acid (HOCl), and hydroxyl radical (OH-).
Oxidative species are produced not only under pathological situations (cancers, ischemic/reperfusion, neurologic and cardiovascular pathologies, infectious diseases, inflammatory diseases 1, autoimmune diseases 2, etc&hellip;) but also during physiological (non-pathological) situations such as cellular metabolism 3, 4. Indeed, ROS play important roles in many cellular signaling pathways (proliferation, cell activation 5, 6, migration 7 etc..). ROS can be detrimental (it is then referred to as "oxidative and nitrosative stress") when produced in high amounts in the intracellular compartments and cells generally respond to ROS by upregulating antioxidants such as superoxide dismutase (SOD) and catalase (CAT), glutathione peroxidase (GPx) and glutathione (GSH) that protects them by converting dangerous free radicals to harmless molecules (i.e. water). Vitamins C and E have also been described as ROS scavengers (antioxidants).
Free radicals are beneficial in low amounts 3. Macrophage and neutrophils-mediated immune responses involve the production and release of NO, which inhibits viruses, pathogens and tumor proliferation 8. NO also reacts with other ROS and thus, also has a role as a detoxifier (ROS scavenger). Finally NO acts on vessels to regulate blood flow which is important for the adaptation of muscle to prolonged exercise 9, 10. Several publications have also demonstrated that ROS are involved in insulin sensitivity 11, 12.
Numerous methods to evaluate ROS production are available. In this article we propose several simple, fast, and affordable assays; these assays have been validated by many publications and are routinely used to detect ROS or its effects in mammalian cells. While some of these assays detect multiple ROS, others detect only a single ROS.

Production and Detection of Reactive Oxygen Species ROS in Cancers

Here we propose simple methods to test and evaluate the presence of reactive oxygen species in cells.

Reactive oxygen species include a number of molecules that damage DNA and RNA and oxidize proteins and lipids (lipid peroxydation). These reactive ...

Labeling Stem Cells with Ferumoxytol, an FDA-Approved Iron Oxide Nanoparticle

Stem cell based therapies offer significant potential for the field of regenerative medicine. However, much remains to be understood regarding the in vivo kinetics of transplanted cells. A non-invasive method to repetitively monitor transplanted stem cells in vivo would allow investigators to directly monitor stem cell transplants and identify successful or unsuccessful engraftment outcomes.
A wide range of stem cells continues to be investigated for countless applications. This protocol focuses on 3 different stem cell populations: human embryonic kidney 293 (HEK293) cells, human mesenchymal stem cells (hMSC) and induced pluripotent stem (iPS) cells. HEK 293 cells are derived from human embryonic kidney cells grown in culture with sheared adenovirus 5 DNA. These cells are widely used in research because they are easily cultured, grow quickly and are easily transfected. hMSCs are found in adult marrow. These cells can be replicated as undifferentiated cells while maintaining multipotency or the potential to differentiate into a limited number of cell fates. hMSCs can differentiate to lineages of mesenchymal tissues, including osteoblasts, adipocytes, chondrocytes, tendon, muscle, and marrow stroma. iPS cells are genetically reprogrammed adult cells that have been modified to express genes and factors similar to defining properties of embryonic stem cells. These cells are pluripotent meaning they have the capacity to differentiate into all cell lineages 1. Both hMSCs and iPS cells have demonstrated tissue regenerative capacity in-vivo.
Magnetic resonance (MR) imaging together with the use of superparamagnetic iron oxide (SPIO) nanoparticle cell labels have proven effective for in vivo tracking of stem cells due to the near microscopic anatomical resolution, a longer blood half-life that permits longitudinal imaging and the high sensitivity for cell detection provided by MR imaging of SPIO nanoparticles 2-4. In addition, MR imaging with the use of SPIOs is clinically translatable. SPIOs are composed of an iron oxide core with a dextran, carboxydextran or starch surface coat that serves to contain the bioreactive iron core from plasma components. These agents create local magnetic field inhomogeneities that lead to a decreased signal on T2-weighted MR images 5. Unfortunately, SPIOs are no longer being manufactured. Second generation, ultrasmall SPIOs (USPIO), however, offer a viable alternative. Ferumoxytol (FerahemeTM) is one USPIO composed of a non-stoichiometric magnetite core surrounded by a polyglucose sorbitol carboxymethylether coat. The colloidal, particle size of ferumoxytol is 17-30 nm as determined by light scattering. The molecular weight is 750 kDa, and the relaxivity constant at 2T MRI field is 58.609 mM-1 sec-1 strength4. Ferumoxytol was recently FDA-approved as an iron supplement for treatment of iron deficiency in patients with renal failure 6. Our group has applied this agent in an &ldquo;off label&rdquo; use for cell labeling applications. Our technique demonstrates efficient labeling of stem cells with ferumoxytol that leads to significant MR signal effects of labeled cells on MR images. This technique may be applied for non-invasive monitoring of stem cell therapies in pre-clinical and clinical settings.

We describe a technique for labeling and tracking stem cells with FDA-approved, superparamagnetic iron oxide (SPIO), ferumoxytol (Feraheme). This cellular imaging technique that utilizes magnetic resonance (MR) imaging for visualization, is readily accessible for long-term monitoring and diagnosis of successful or unsuccessful stem cell engraftments in patients.

Stem cell based therapies offer significant potential for the field of regenerative medicine. However, much remains to be understood regarding the in vivo ...

Analytical Techniques for Assaying Nitric Oxide Bioactivity

Nitric oxide (NO) is a diatomic free radical that is extremely short lived in biological systems (less than 1 second in circulating blood)1. NO may be considered one of the most important signaling molecules produced in our body, regulating essential functions including but not limited to regulation of blood pressure, immune response and neural communication. Therefore its accurate detection and quantification in biological matrices is critical to understanding the role of NO in health and disease. With such a short physiological half life of NO, alternative strategies for the detection of reaction products of NO biochemistry have been developed. The quantification of relevant NO metabolites in multiple biological compartments provides valuable information with regards to in vivo NO production, bioavailability and metabolism. Simply sampling a single compartment such as blood or plasma may not always provide an accurate assessment of whole body NO status, particularly in tissues. The ability to compare blood with select tissues in experimental animals will help bridge the gap between basic science and clinical medicine as far as diagnostic and prognostic utility of NO biomarkers in health and disease. Therefore, extrapolation of plasma or blood NO status to specific tissues of interest is no longer a valid approach. As a result, methods continue to be developed and validated which allow the detection and quantification of NO and NO-related products/metabolites in multiple compartments of experimental animals in vivo. The established paradigm of NO biochemistry from production by NO synthases to activation of soluble guanylyl cyclase (sGC) to eventual oxidation to nitrite (NO2-) and nitrate (NO3-) may only represent part of NO's effects in vivo. The interaction of NO and NO-derived metabolites with protein thiols, secondary amines, and metals to form S-nitrosothiols (RSNOs), N-nitrosamines (RNNOs), and nitrosyl-heme respectively represent cGMP-independent effects of NO and are likely just as important physiologically as activation of sGC by NO. A true understanding of NO in physiology is derived from in vivo experiments sampling multiple compartments simultaneously. Nitric oxide (NO) methodology is a complex and often confusing science and the focus of many debates and discussion concerning NO biochemistry. The elucidation of new mechanisms and signaling pathways involving NO hinges on our ability to specifically, selectively and sensitively detect and quantify NO and all relevant NO products and metabolites in complex biological matrices. Here, we present a method for the rapid and sensitive analysis of nitrite and nitrate by HPLC as well as detection of free NO in biological samples using in vitro ozone based chemiluminescence with chemical derivitazation to determine molecular source of NO as well as ex vivo with organ bath myography.

The endogenous production of nitric oxide (NO) regulates a wide variety of biological functions. It is becoming increasingly clear that disruption or dysregulation of NO based signaling is involved in many human diseases. Methods to quantify relevant NO metabolites may provide novel diagnostic or prognostic biomarkers for human disease.

Nitric oxide (NO) is a diatomic free radical that is extremely short lived in biological systems (less than 1 second in circulating blood)1. NO may be ...

Cerenkov Luminescence Imaging (CLI) for Cancer Therapy Monitoring

In molecular imaging, positron emission tomography (PET) and optical imaging (OI) are two of the most important and thus most widely used modalities1-3. PET is characterized by its excellent sensitivity and quantification ability while OI is notable for non-radiation, relative low cost, short scanning time, high throughput, and wide availability to basic researchers. However, both modalities have their shortcomings as well. PET suffers from poor spatial resolution and high cost, while OI is mostly limited to preclinical applications because of its limited tissue penetration along with prominent scattering optical signals through the thickness of living tissues.
 Recently a bridge between PET and OI has emerged with the discovery of Cerenkov Luminescence Imaging (CLI)4-6. CLI is a new imaging modality that harnesses Cerenkov Radiation (CR) to image radionuclides with OI instruments. Russian Nobel laureate Alekseyevich Cerenkov and his colleagues originally discovered CR in 1934. It is a form of electromagnetic radiation emitted when a charged particle travels at a superluminal speed in a dielectric medium7,8. The charged particle, whether positron or electron, perturbs the electromagnetic field of the medium by displacing the electrons in its atoms. After passing of the disruption photons are emitted as the displaced electrons return to the ground state. For instance, one 18F decay was estimated to produce an average of 3 photons in water5. 
 Since its emergence, CLI has been investigated for its use in a variety of preclinical applications including in vivo tumor imaging, reporter gene imaging, radiotracer development, multimodality imaging, among others4,5,9,10,11. The most important reason why CLI has enjoyed much success so far is that this new technology takes advantage of the low cost and wide availability of OI to image radionuclides, which used to be imaged only by more expensive and less available nuclear imaging modalities such as PET.
 Here, we present the method of using CLI to monitor cancer drug therapy. Our group has recently investigated this new application and validated its feasibility by a proof-of-concept study12. We demonstrated that CLI and PET exhibited excellent correlations across different tumor xenografts and imaging probes. This is consistent with the overarching principle of CR that CLI essentially visualizes the same radionuclides as PET. We selected Bevacizumab (Avastin; Genentech/Roche) as our therapeutic agent because it is a well-known angiogenesis inhibitor13,14. Maturation of this technology in the near future can be envisioned to have a significant impact on preclinical drug development, screening, as well as therapy monitoring of patients receiving treatments.

Cerenkov Luminescence Imaging CLI for Cancer Therapy Monitoring

Use of Cerenkov Luminescence Imaging (CLI) for monitoring preclinical cancer treatment is described here. This method takes advantage of Cerenkov Radiation (CR) and optical imaging (OI) to visualize radiolabeled probes and thus provides an alternative to PET in preclinical therapeutic monitoring and drug screening.

In  molecular imaging, positron emission tomography (PET) and optical imaging (OI)  are two of the most important and thus most widely used modalities1-3. ...

Establishment and Characterization of UTI and CAUTI in a Mouse Model

Urinary tract infections (UTI) are highly prevalent, a significant cause of morbidity and are increasingly resistant to treatment with antibiotics. Females are disproportionately afflicted by UTI: 50% of all women will have a UTI in their lifetime. Additionally, 20-40% of these women who have an initial UTI will suffer a recurrence with some suffering frequent recurrences with serious deterioration in the quality of life, pain and discomfort, disruption of daily activities, increased healthcare costs, and few treatment options other than long-term antibiotic prophylaxis. Uropathogenic Escherichia coli (UPEC) is the primary causative agent of community acquired UTI. Catheter-associated UTI (CAUTI) is the most common hospital acquired infection accounting for a million occurrences in the US annually and dramatic healthcare costs. While UPEC is also the primary cause of CAUTI, other causative agents are of increased significance including Enterococcus faecalis. Here we utilize two well-established mouse models that recapitulate many of the clinical characteristics of these human diseases. For UTI, a C3H/HeN model recapitulates many of the features of UPEC virulence observed in humans including host responses, IBC formation and filamentation. For CAUTI, a model using C57BL/6 mice, which retain catheter bladder implants, has been shown to be susceptible to E. faecalis bladder infection. These representative models are being used to gain striking new insights into the pathogenesis of UTI disease, which is leading to the development of novel therapeutics and management or prevention strategies.

The ability to model urinary tract infections (UTI) is crucial in order to be able to understand bacterial pathogenesis and spawn the development of novel therapeutics. This work&#8217;s goal is to demonstrate mouse models of experimental UTI and catheter associated UTI that recapitulate and predict findings seen in humans.

Urinary tract infections (UTI) are highly prevalent, a significant cause of morbidity and are increasingly resistant to treatment with antibiotics. ...

Platelet-based Detection of Nitric Oxide in Blood by Measuring VASP Phosphorylation

Platelets are the blood components responsible for proper blood clotting. Their function is highly regulated by various pathways. One of the most potent vasoactive agents, nitric oxide (NO), can also act as a powerful inhibitor of platelet aggregation. Direct NO detection in blood is very challenging due to its high reactivity with cell-free hemoglobin that limits NO half-life to the millisecond range. Currently, NO changes after interventions are only estimated based on measured changes of nitrite and nitrate (members of the nitrate-nitrite-NO metabolic pathway). However precise, these measurements are rather difficult to interpret vis a vis actual NO changes, due to the naturally high baseline nitrite and nitrate levels that are several orders of magnitude higher than expected changes of NO itself. Therefore, the development of direct and simple methods that would allow one to detect NO directly is long overdue. This protocol addresses a potential use of platelets as a highly sensitive NO sensor in blood. It describes initial platelet rich plasma (PRP) and washed platelet preparations and the use of nitrite and deoxygenated red blood cells as NO generators. Phosphorylation of VASP at serine 239 (P-VASPSer239) is used to detect the presence of NO. The fact that VASP protein is highly expressed in platelets and that it is rapidly phosphorylated when NO is present leads to a unique opportunity to use this pathway to directly detect NO presence in blood.

Here, we present a protocol to address the potential use of platelets as a highly sensitive nitric oxide sensor in blood. It describes initial platelet preparation and the use of nitrite and deoxygenated red blood cells as nitric oxide generators.

Platelets are the blood components responsible for proper blood clotting. Their function is highly regulated by various pathways. One of the most potent ...

Polyethyleneimine-coated Iron Oxide Nanoparticles as a Vehicle for the Delivery of Small Interfering RNA to Macrophages In Vitro and In Vivo

Because of their critical role in regulating immune responses, macrophages have continuously been the subject of intensive research and represent a promising therapeutic target in many disorders, such as autoimmune diseases, atherosclerosis, and cancer. RNAi-mediated gene silencing is a valuable approach of choice to probe and manipulate macrophage function; however, the transfection of macrophages with siRNA is often considered to be technically challenging, and, at present, few methodologies dedicated to the siRNA transfer to macrophages are available. Here, we present a protocol of using polyethyleneimine-coated superparamagnetic iron oxide nanoparticles (PEI-SPIONs) as a vehicle for the targeted delivery of siRNA to macrophages. PEI-SPIONs are capable of binding and completely condensing siRNA when the Fe:siRNA weight ratio reaches 4 and above. In vitro, these nanoparticles can efficiently deliver siRNA into primary macrophages, as well as into the macrophage-like RAW 264.7 cell line, without compromising cell viability at the optimal dose for transfection, and, ultimately, they induce siRNA-mediated target gene silencing. Apart from being used for in vitro siRNA transfection, PEI-SPIONs are also a promising tool for delivering siRNA to macrophages in vivo. In view of its combined features of magnetic property and gene-silencing ability, systemically administered PEI-SPION/siRNA particles are expected not only to modulate macrophage function but also to enable macrophages to be imaged and tracked. In essence, PEI-SPIONs represent a simple, safe, and effective nonviral platform for siRNA delivery to macrophages both in vitro and in vivo.

Polyethyleneimine-coated Iron Oxide Nanoparticles as a Vehicle for the Delivery of Small Interfering RNA to Macrophages In Vitro and In Vivo

We describe a method of using polyethyleneimine (PEI)-coated superparamagnetic iron oxide nanoparticles for transfecting macrophages with siRNA. These nanoparticles can efficiently deliver siRNA to macrophages in vitro and in vivo and silence target gene expression.

Because of their critical role in regulating immune responses, macrophages have continuously been the subject of intensive research and represent a ...

Assessment and Characterization of Hyaloid Vessels in Mice

In the eye, the embryonic hyaloid vessels nourish the developing lens and retina and regress when the retinal vessels develop. Persistent or failed regression of hyaloid vessels can be seen in diseases such as persistent hyperplastic primary vitreous (PHPV), leading to an obstructed light path and impaired visual function. Understanding the mechanisms underlying the hyaloid vessel regression may lead to new molecular insights into the vascular regression process and potential new ways to manage diseases with persistent hyaloid vessels. Here we describe the procedures for imaging hyaloid in live mice with optical coherence tomography (OCT) and fundus fluorescein angiography (FFA) and a detailed technical protocol of isolating and flat-mounting hyaloid ex vivo for quantitative analysis. Low-density lipoprotein receptor-related protein 5 (LRP5) knockout mice were used as an experimental model of persistent hyaloid vessels, to illustrate the techniques. Together, these techniques may facilitate a thorough assessment of hyaloid vessels as an experimental model of vascular regression and studies on the mechanism of persistent hyaloid vessels.

This protocol describes both in vivo and ex vivo methods to fully visualize and characterize hyaloid vessels, a model of vascular regression in mouse eyes, using optical coherence tomography and fundus fluorescein angiography for the live imaging and ex vivo isolation and subsequent flat mount of hyaloid for quantitative analysis.

In the eye, the embryonic hyaloid vessels nourish the developing lens and retina and regress when the retinal vessels develop. Persistent or failed ...

Tracking Superparamagnetic Iron Oxide-labeled Mesenchymal Stem Cells using MRI after Intranasal Delivery in a Traumatic Brain Injury Murine Model

Stem cell-based therapies for brain injuries, such as traumatic brain injury (TBI), are a promising approach for clinical trials. However, technical hurdles such as invasive cell delivery and tracking with low transplantation efficiency remain challenges in translational stem-based therapy. This article describes an emerging technique for stem cell labeling and tracking based on the labeling of the mesenchymal stem cells (MSCs) with superparamagnetic iron oxide (SPIO)&#160;nanoparticles, as well as intranasal delivery of the labeled MSCs. These nanoparticles are fluorescein isothiocyanate (FITC)-embedded and safe to label the MSCs, which are subsequently delivered to the brains of TBI-induced mice by the intranasal route. They are then tracked non-invasively in vivo by real-time magnetic resonance imaging (MRI). Important advantages of this technique that combines SPIO for cell labeling and intranasal delivery include (1) non-invasive, in vivo MSC tracking after delivery for long tracking periods, (2) the possibility of multiple dosing regimens due to the non-invasive route of MSC delivery, and (3) possible applications to humans, owing to the safety of SPIO, non-invasive nature of the cell-tracking method by MRI, and route of administration.

Presented here is a protocol for non-invasive mesenchymal stem cell (MSC) delivery and tracking in a mouse model of traumatic brain injury. Superparamagnetic iron oxide&#160;nanoparticles are employed as a magnetic resonance imaging (MRI) probe for MSC labeling and non-invasive in vivo tracking following intranasal delivery using real-time MRI.

Stem cell-based therapies for brain injuries, such as traumatic brain injury (TBI), are a promising approach for clinical trials. However, technical ...

Synthesis and Characterization of Multi-Modal Phase-Change Porphyrin Droplets

Phase-change droplets are a class of ultrasound contrast agents that can convert into echogenic microbubbles in situ with the application of sufficient acoustic energy. Droplets are smaller and more stable than their microbubble counterparts. However, traditional ultrasound contrast agents are not trackable beyond acoustic feedback measurements, which makes quantifying contrast agent bio-distribution or accumulation ex vivo difficult. Researchers may have to rely on fluorescent or optically absorbent companion diagnostic particles to infer bio-distribution. The purpose of this protocol is to detail steps for creating multi-modal phase-change porphyrin droplets using a condensation method. Porphyrins are fluorescent molecules with distinct absorbance bands that can be conjugated onto lipids and incorporated into droplets to extend droplet versatility, enabling more robust bio-distribution while retaining acoustic properties. Seven formulations with varying porphyrin-lipid and base lipid contents were made to investigate microbubble and droplet size distributions. Characterizations suited to porphyrin-containing structures are also described in the protocol to demonstrate their analytic versatility in-solution. Sizing showed that the post-condensed mean diameters were 1.72 to 2.38 times smaller than precursor populations. Absorbance characterization showed intact assemblies had a Q-band peak of 700 nm while disrupted samples had an absorbance peak at 671 nm. Fluorescence characterization showed intact 30% porphyrin-lipid assemblies were fluorescently quenched (&gt;97%), with fluorescence recovery achieved upon disruption. Acoustic vaporization showed that porphyrin droplets were non-echogenic at lower pressures and could be converted into echogenic microbubbles with sufficient pressures. These characterizations show the potential for porphyrin droplets to eliminate the need for absorbance or fluorescence-based companion diagnostic strategies to quantify ultrasound contrast agent bio-distribution for delivery or therapeutic applications in vivo or ex vivo.

In this protocol, methods for synthesizing and characterizing multi-modal phase-change porphyrin droplets are outlined.

Phase-change droplets are a class of ultrasound contrast agents that can convert into echogenic microbubbles in situ with the application of sufficient ...