Name: quantitative visualization of leukocyte infiltrate in a murine model of fulminant myocarditis by light sheet microscopy
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Description: Watch this Scientific Journal Video about Quantitative Visualization of Leukocyte Infiltrate in a Murine Model of Fulminant Myocarditis by Light Sheet Microscopy at JoVE.com

Research in the Gunzer laboratory was supported by the German Federal Ministry of Education and Research (grant no. 0315590 A-D) and by the German Research Foundation (grant no. GU769/4-1, GU769/4-2). We further thank the IMCES for technical support and Sebastian Kubat for help with 3D cartoon modeling.

All animal experiments were conducted in accordance with EU guidelines and were approved by the relevant local authorities in Essen (AZ 84-02.04.2014.A036 - Landesamt f&#252;r Natur, Umwelt und Verbraucherschutz Nordrhein-Westfalen, Essen, Germany). The animals were used and housed under specific pathogen-free (SPF) conditions.
1. Induction of Myocarditis by Diphtheria Toxin (DTX)
<ol>
	<li>Prepare the DTX solution for the induction of myocarditis by diluting the DTX stock solution with phos...

<ol>
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In modern life science, the microscopic visualization of biological processes plays an increasingly important role. In this context, many developments have been achieved during the last two centuries that help to answer questions not addressable up to this point, . First, there has been a clear tendency to fundamentally increase the resolution ability of light microscopes. With structured illumination microscopy (SIM)21,22, stimulated emission-depletion (STED) mi...

During the evolution of light microscopy, many specialized forms appeared, all of them developed to minimize limitations in the visualization process for particular specimens. One such method is light-sheet fluorescence microscopy (LSFM). First developed in 1903 by Siedentopf and Zsigmondy1 and finding its first fundamental biological applications in the early 1990s2, LSFM has become the most powerful microscopic tool to date for the visualization of large specimens, such as intact mouse organs, with a fluorescence signal resolution down to the cellular level. Because of these benefits, in combination with its potential for live-cell imaging, Nature Methods named LSFM the &#34;Method of the Year 20143.&#34;
As the name suggests, the sample illumination in an LSFM is conducted by light sheets, which are orientated perpendicularly to the axis of the objective used for emission-light collection and subsequent image formation. The light sheet is usually generated either by focusing wide, collimated laser beams with a cylindrical lens or by the rapid sideways movement of narrow, focused laser beams in just one horizontal or vertical plane4,5. In this way, only the focal plane of the imaging optics is illuminated, typically with a thickness of 1-4 &#181;m. Consequently, for a fluorescent sample placed in the illumination plane, both the generation of scattered light and the effects of photobleaching from regions above or below the focal plane are eliminated or greatly suppressed6,7. As all out-of-focus planes are not illuminated, photobleaching effects are omitted in these areas. In contrast to standard confocal or multi-photon microscopy, the paths of illuminated and emitted light are separate from each other, so the final image quality does not depend on the perfect focusing of the excitation light beam through the objectives. Depending on the underlying question, it is therefore possible to use objectives with an enormous field of view (FOV) so that the largest possible area of the illuminated plane can be imaged without any component parts moving in the xy-direction.
In modern LSFM systems, a fluorescent image of the generated optical section is captured on a highly sensitive charge-coupled device (CCD) or complementary metal-oxide semiconductor (CMOS) cameras, which are able to acquire the entire field of view (FOV) in microseconds. Therefore, by moving the sample through the light sheet and by acquiring images at defined z-steps, it is possible to obtain the full 3D information of a specimen in a reasonable amount of time8,9, making this technique applicable for live-cell studies10,11,12.
Nevertheless, although LSFM offers a rapid, sensitive, and fluorescence-friendly method, light transmission through the specimen is still a major issue, especially when large biological samples are the target for a 3D analysis. Light transmission is critically modified by physical aspects of absorption and by light scattering at interfaces of structures with different refractive indices13. Therefore, when imaging samples several millimeters in size, LSFM is mostly combined with clearing protocols to render the samples optically transparent. These techniques are based on the idea of removing water from the respective biological tissue and exchanging it with water- or (organic) solvent-based immersion media, which are chosen to narrowly match the refractive indices of the particular target tissue components. As a result, lateral light scattering is minimized, and all wavelengths of light can much more efficiently pass through the tissue13. In many cases, biological specimens treated in this way appear macroscopically crystal-clear, which enables LSFM to be conducted, even on entire mouse organs, using long working-distance, low magnification objectives.
Here, we present a preparation protocol for large-sample imaging in a light-sheet microscope (see the table of materials), which we have established to investigate the cellular cardiac infiltrate in a murine model of myocarditis15. CD11c.DTR mice express the primate diphtheria toxin receptor (DTR) under the control of the CD11c promotor16. Consequently, cells in these mice, which express CD11c along with the DTR, are rendered sensitive to the exotoxin of Corynebacterium diphtheria (diphtheria toxin, DTX); the systemic treatment of these animals with DTX results in a depletion of all CD11c+ cells. CD11c is an integrin and, as a cell-surface receptor for a variety of different soluble factors, is involved in activation and maturation processes mainly in cells of the monocytic lineage17. Consequently, the CD11c.DTR mouse model has been intensively used to study the role of dendritic cells and macrophage subsets in the context of many different immunological questions. Over time, it has been reported that CD11c.DTR mice treated systemically with DTX can develop adverse side effects and can display strongly elevated mortality rates18,19. Recently, we were able to identify the underlying cause of death15, describing the development of fulminant myocarditis after intratracheal DTX application in these animals. The toxin challenge caused cellular destruction, including in central parts of the stimulus transmission system in the heart. This was accompanied by massive CD45+ leukocyte infiltrate, finally leading to lethal cardiac arrhythmias. In this case, not only was the appearance of the leukocyte population important, but also its spatial distribution inside the heart. This experimental question is a challenge for modern microscopic imaging, which we have solved by a light-sheet microscopy approach that is supported by intravital antibody staining and an organic solvent-based optical clearing protocol.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>diphtheria toxin</td>
			<td>Sigma Aldrich</td>
			<td>D0564</td>
			<td></td>
		</tr>
		<tr>
			<td>phosphate buffered saline</td>
			<td>Biochrom</td>
			<td>L182-10</td>
			<td></td>
		</tr>
		<tr>
			<td>ketamine [50 mg/ml]</td>
			<td>Inresa</td>
			<td>PZN 4089014</td>
			<td></td>
		</tr>
		<tr>
			<td>xylazine [2 %]</td>
			<td>Ceva</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>syringe</td>
			<td>Braun</td>
			<td>REF 9161502</td>
			<td>Braun Omincan F&#160;</td>
		</tr>
		<tr>
			<td>indwelt venous catheter&#160;</td>
			<td>Becton Dickinson</td>
			<td>REF 381923</td>
			<td>BD Insyte Autoguard</td>
		</tr>
		<tr>
			<td>small animal respirator</td>
			<td>Harvard Apparatus</td>
			<td>73-0044</td>
			<td>MiniVent</td>
		</tr>
		<tr>
			<td>anit-CD45 antibody (AF647)</td>
			<td>BioLegend</td>
			<td>103124</td>
			<td></td>
		</tr>
		<tr>
			<td>ethylenediaminetetraacetic acid (EDTA) disodium salt dihydrate</td>
			<td>Carl Roth</td>
			<td>8043.2</td>
			<td></td>
		</tr>
		<tr>
			<td>catheter (21 G)</td>
			<td>BD Biosciences</td>
			<td>REF 387455</td>
			<td>BD valu-set</td>
		</tr>
		<tr>
			<td>paraformaldehyde</td>
			<td>Sigma Aldrich</td>
			<td>P6148</td>
			<td></td>
		</tr>
		<tr>
			<td>PE tube (5 ml)</td>
			<td>Carl Roth</td>
			<td>EKY9.1</td>
			<td>Rotilabo</td>
		</tr>
		<tr>
			<td>ethanol</td>
			<td>Carl Roth</td>
			<td>9065.4</td>
			<td></td>
		</tr>
		<tr>
			<td>dibenzyl ether</td>
			<td>Sigma-Aldrich</td>
			<td>108014</td>
			<td></td>
		</tr>
		<tr>
			<td>tube rotator</td>
			<td>Miltenyi Biotec</td>
			<td>130-090-753</td>
			<td>MACSmix</td>
		</tr>
		<tr>
			<td>agarose (low gelling)</td>
			<td>Sigma Aldrich</td>
			<td>A4018</td>
			<td></td>
		</tr>
		<tr>
			<td>mold (15x15x5 mm)</td>
			<td>Tissue Tek</td>
			<td>4566</td>
			<td>Cryomold&#160;</td>
		</tr>
		<tr>
			<td>light sheet microscope system</td>
			<td>LaVision Biotec</td>
			<td></td>
			<td>Ultramicroscope&#160;</td>
		</tr>
		<tr>
			<td>microscope body</td>
			<td>Olympus</td>
			<td></td>
			<td>MVX10&#160;</td>
		</tr>
		<tr>
			<td>objective</td>
			<td>Olympus</td>
			<td></td>
			<td>0.5&#160;NA MVPLAPO 2XC, WD 5.5&#160;mm&#160;</td>
		</tr>
		<tr>
			<td>sCMOS camera 5.5MP</td>
			<td>Andor Technology</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>488 nm OPSL (50mW) laser</td>
			<td>Coherent</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>647 nm&#160; diode laser (50mW)</td>
			<td>Coherent</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>3D image processing &#38; analysis software</td>
			<td>Bitplane</td>
			<td></td>
			<td>IMARIS Ver. 8.3</td>
		</tr>
		<tr>
			<td>transgenic mouse strain</td>
			<td>Steffen Jung et al.</td>
			<td></td>
			<td>CD11c.DTR</td>
		</tr>
		<tr>
			<td>wt mouse strain</td>
			<td>Envigo</td>
			<td></td>
			<td>Balb/c Ola Hsd J</td>
		</tr>
		<tr>
			<td>Laser Module</td>
			<td>LaVision Biotec</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>MVPLAPO 2XC Objective Lens</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

quantitative visualization of leukocyte infiltrate in a murine model of fulminant myocarditis by light sheet microscopy

Light-sheet fluorescence microscopy (LSFM), in combination with chemical clearing protocols, has become the gold standard for analyzing fluorescently labelled structures in large biological specimens, and is down to cellular resolution. Meanwhile, the constant refinement of underlying protocols and the enhanced availability of specialized commercial systems enable us to investigate the microstructure of whole mouse organs and even allow for the characterization of cellular behavior in various live-cell imaging approaches. Here, we describe a protocol for the spatial whole-mount visualization and quantification of the CD45+ leukocyte population in inflamed mouse hearts. The method employs a transgenic mouse strain (CD11c.DTR)that has recently been shown to serve as a robust, inducible model for the study of the development of fulminant fatal myocarditis, characterized by lethal cardiac arrhythmias. This protocol includes myocarditis induction, intravital antibody-mediated cell staining, organ preparation, and LSFM with subsequent computer-assisted image post-processing. Although presented as a highly-adapted method for our particular scientific question, the protocol represents the blueprint of an easily adjustable system that can also target completely different fluorescent structures in other organs and even in other species.

The presented LSFM approach analyzes the leukocyte distribution and amount in murine hearts upon induction of severe myocarditis. Figure 1A explains the pre-treatment protocol for the transgenic CD11c.DTR mice for myocarditis induction. This step represents the necessary trigger for the recruitment of leukocytes to the myocardium. After successful DTX application, the animals develop severe disease symptoms, such as general weakness, anorexia, and weight loss within the r...

Watch this Scientific Journal Video about Quantitative Visualization of Leukocyte Infiltrate in a Murine Model of Fulminant Myocarditis by Light Sheet Microscopy at JoVE.com

Quantitative Visualization of Leukocyte Infiltrate in a Murine Model of Fulminant Myocarditis by Light Sheet Microscopy

Here, we describe a light-sheet microscopy approach to visualize the cardiac CD45+ leukocyte infiltrate in a murine model of aseptic fulminant myocarditis, which is induced by the intratracheal diphtheria toxin treatment of CD11c.DTR mice.

Light-sheet fluorescence microscopy (LSFM), in combination with chemical clearing protocols, has become the gold standard for analyzing fluorescently ...

The overall goal of this protocol is to chemically clear the heart of a mouse, with an induced cardiac arrhythmia for a whole organ visualization of the leukocytic cardiac infiltrate by Fluorescence Light Sheet Microscopy. This method can help answer key questions in the field of whole organ research about prosthesis and structures at the cellular resolution level. The main advantage of this technique is that it allows both the quantification and the localisation of inflammation in whole organs.Giving detailed insides into neurological prosthesis. We first had the idea for this method when we were in urgent need of a visualization tool to identify cellular explanations for cardiac arrhythmia in the depletion module. After exposition of the heart from an eight to 10 week old mouse, use a 21 gauge catheter and penetrate the right ventricle.Incise the aorta to allow blood drainage and then perfuse with five milliliters of PBS plus EDTA, with a slow constant pressure. Follow the PBS EDTA with five milliliters of 4%paraformaldehyde. At the end of the perfusion, use serrated forceps to gently grasp the fixed heart, and pull the organ slightly upwards to cut all of the tissue connections.Including the incoming and outgoing arteries and veins. Then, store the heart for four hours in fresh 4%PFA for further fixation. To dehydrate the tissue, incubate the heart in an ascending ethanol series, in black five milliliter polypropylene reaction tubes in the dark, with constant slow rotation on a tube rotator, to prevent air bubble formation.Then, clear the tissue with a 98%dibenzyl ether incubation with constant rotation overnight. To conduct Light Sheet Fluorescence Microscopy, first place dehydrated agarose blocks into the standard sample holder, to hold the sample in place. Then, transfer the sample onto the sample holder.Next, transfer the sample holder into an appropriately sized dibenzyl ether filled cuvette. Use the appropriate excitation and emission filter settings, to detect the fluorescence signals of interest. So correct positioning and fixation of the sample is fundamental to minimize shadowing effects during imaging.Further, a loose specimen can cause moving artifacts, which are hard to illuminate during post-processing. After requiring all of the images, open the appropriate 3D and 4D image processing analysis software, and select surpass. Choose file and open, and select the folder containing the data from the first acquired channel to open the image stacks.Select edit and add channels, to add the appropriate acquired fluorescent channel data. Next, click edit and select image properties, to correct the x, y and z voxel dimensions. Adjusting the parameters in the newly opened window.To adjust the fluorescent signals, first open the edit menu and select, show display adjustment. A new window very display all of the open channels. To change the autofluorescence channel to greyscale, select the autofluorescence channel, choose the white display style and click okay.Then, adjust the view by removing the grid. Then, zoom in and deselect one channel. Then, adjust the black level value to exclude any unwanted background signals that do not represent the sample structures, the signal intensity and the contrast.Adjust the antibody standing channel in relation to the revised autofluorescence channel signal. Setting the channel mode, fire to set the visualization of the antibody signal to a heat map color lookup table. Then, select the blend mode, to visualize the tissue structures in detail.To virtually cut open the organ, before the 3D scene export, select the clipping plane icon in the object list. A yellow frame and a white spindle manipulator will appear in the image view. Use the mouse to rotate the spindle at the thinner end, to change the orientation of the clipping plane, and move the thicker middle part of the spindle to select the desired depth of clipping.Then, uncheck the respective check boxes to hide the frame and manipulator and create the desired snapshots. The acquisition of an entire image stack, composed of two fluorescent channel signals, elicits an artificial 3D rendering, in which the leukocyte distribution is displayed in a heat map view. The strongly inflamed areas of hearts from a Diphtheria toxin treated animal can be perceived by their reddish, whitish appearances.Particularly in the regions of the cardiac conduction system, such as the atrial ventricular bundle and the Purkinje fibers. In contrast, the hearts of controlled PBS treated animals, do not demonstrate this pattern of inflammation. Once mastered, this technique allows the digital ready analysis of a target organ, from its harvest to its computer assisted rendification in four to five days.After its development, this technique paved the way for researchers in the field of emmenology, to explore cellular distribution patterns in whole mouse organs. This may age in the analysis and the treatment of a variety of pathophysiological disease prosthesis. After watching this video, you should have a good understanding of how to prepare whole mouse organs for Fluorescence Light Sheet Microscopy and how to generate and process 3D data stacks.

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Research

JoVE Journal

Medicine

A Murine Model of Muscle Training by Neuromuscular Electrical Stimulation

Neuromuscular electrical stimulation (NMES) is a common clinical modality that is widely used to restore1, maintain2 or enhance3-5 muscle functional capacity. Transcutaneous surface stimulation of skeletal muscle involves a current flow between a cathode and an anode, thereby inducing excitement of the motor unit and the surrounding muscle fibers. 
NMES is an attractive modality to evaluate skeletal muscle adaptive responses for several reasons. First, it provides a reproducible experimental model in which physiological adaptations, such as myofiber hypertophy and muscle strengthening6, angiogenesis7-9, growth factor secretion9-11, and muscle precursor cell activation12 are well documented. Such physiological responses may be carefully titrated using different parameters of stimulation (for Cochrane review, see 13). In addition, NMES recruits motor units non-selectively, and in a spatially fixed and temporally synchronous manner14, offering the advantage of exerting a treatment effect on all fibers, regardless of fiber type. Although there are specified contraindications to NMES in clinical populations, including peripheral venous disorders or malignancy, for example, NMES is safe and feasible, even for those who are ill and/or bedridden and for populations in which rigorous exercise may be challenging. 
Here, we demonstrate the protocol for adapting commercially available electrodes and performing a NMES protocol using a murine model. This animal model has the advantage of utilizing a clinically available device and providing instant feedback regarding positioning of the electrode to elicit the desired muscle contractile effect. For the purpose of this manuscript, we will describe the protocol for muscle stimulation of the anterior compartment muscles of a mouse hindlimb.

A murine model of neuromuscular electrical stimulation (NMES), a safe and inexpensive clinical modality, to the anterior compartment muscles is described. This model has the advantage of modifying a readily available clinical device for the purpose of eliciting targeted and specific muscle contractions in mice.

Neuromuscular electrical stimulation (NMES) is a common clinical modality that is widely used to restore1, maintain2 or enhance3-5 muscle functional ...

Using Quantitative Real-time PCR to Determine Donor Cell Engraftment in a Competitive Murine Bone Marrow Transplantation Model

Murine bone marrow transplantation models provide an important tool in measuring hematopoietic stem cell (HSC) functions and determining genes/molecules that regulate HSCs. In these transplant model systems, the function of HSCs is determined by the ability of these cells to engraft and reconstitute lethally irradiated recipient mice. Commonly, the donor cell contribution/engraftment is measured by antibodies to donor- specific cell surface proteins using flow cytometry. However, this method heavily depends on the specificity and the ability of the cell surface marker to differentiate donor-derived cells from recipient-originated cells, which may not be available for all mouse strains. Considering the various backgrounds of genetically modified mouse strains in the market, this cell surface/ flow cytometry-based method has significant limitations especially in mouse strains that lack well-defined surface markers to separate donor cells from congenic recipient cells. Here, we reported a PCR-based technique to determine donor cell engraftment/contribution in transplant recipient mice. We transplanted male donor bone marrow HSCs to lethally irradiated congenic female mice. Peripheral blood samples were collected at different time points post transplantation. Bone marrow samples were obtained at the end of the experiments. Genomic DNA was isolated and the Y chromosome specific gene, Zfy1, was amplified using quantitative Real time PCR. The engraftment of male donor-derived cells in the female recipient mice was calculated against standard curve with known percentage of male vs. female DNAs. Bcl2 was used as a reference gene to normalize the total DNA amount. Our data suggested that this approach reliably determines donor cell engraftment and provides a useful, yet simple method in measuring hematopoietic cell reconstitution in murine bone marrow transplantation models. Our method can be routinely performed in most laboratories because no costly equipment such as flow cytometry is required.

Determining donor cell engraftment presents a challenge in mouse bone marrow transplant models that lack well-defined phenotypical markers. We described a methodology to quantify male donor cell engraftment in female transplant recipient mice. This method can be used in all mouse strains for the study of HSC functions.

Murine bone marrow transplantation models provide an important tool in measuring hematopoietic stem cell (HSC) functions and determining genes/molecules ...

Murine Model of Wound Healing

Wound healing and repair are the most complex biological processes that occur in human life. After injury, multiple biological pathways become activated. Impaired wound healing, which occurs in diabetic patients for example, can lead to severe unfavorable outcomes such as amputation. There is, therefore, an increasing impetus to develop novel agents that promote wound repair. The testing of these has been limited to large animal models such as swine, which are often impractical. Mice represent the ideal preclinical model, as they are economical and amenable to genetic manipulation, which allows for mechanistic investigation. However, wound healing in a mouse is fundamentally different to that of humans as it primarily occurs via contraction. Our murine model overcomes this by incorporating a splint around the wound. By splinting the wound, the repair process is then dependent on epithelialization, cellular proliferation and angiogenesis, which closely mirror the biological processes of human wound healing. Whilst requiring consistency and care, this murine model does not involve complicated surgical techniques and allows for the robust testing of promising agents that may, for example, promote angiogenesis or inhibit inflammation. Furthermore, each mouse acts as its own control as two wounds are prepared, enabling the application of both the test compound and the vehicle control on the same animal. In conclusion, we demonstrate a practical, easy-to-learn, and robust model of wound healing, which is comparable to that of humans.

A murine model of cutaneous wound healing that can be used to assess therapeutic compounds in physiological and pathophysiological settings.

Wound healing and repair are the most complex biological processes that occur in human life. After injury, multiple biological pathways become activated. ...

A Murine Model of Subarachnoid Hemorrhage

In this video publication a standardized mouse model of subarachnoid hemorrhage (SAH) is presented. Bleeding is induced by endovascular Circle of Willis perforation (CWp) and proven by intracranial pressure (ICP) monitoring. Thereby a homogenous blood distribution in subarachnoid spaces surrounding the arterial circulation and cerebellar fissures is achieved. Animal physiology is maintained by intubation, mechanical ventilation, and continuous on-line monitoring of various physiological and cardiovascular parameters: body temperature, systemic blood pressure, heart rate, and hemoglobin saturation. Thereby the cerebral perfusion pressure can be tightly monitored resulting in a less variable volume of extravasated blood. This allows a better standardization of endovascular filament perforation in mice and makes the whole model highly reproducible. Thus it is readily available for pharmacological and pathophysiological studies in wild type and genetically altered mice.

A standardized mouse model of subarachnoid hemorrhage by intraluminal Circle of Willis perforation is described. Vessel perforation and subarachnoid bleeding are monitored by intracranial pressure monitoring. In addition various vital parameters are recorded and controlled to maintain physiologic conditions.

In this video publication a standardized mouse model of subarachnoid  hemorrhage (SAH) is presented. Bleeding is induced by endovascular Circle of  Willis ...

Reproducable Paraplegia by Thoracic Aortic Occlusion in a Murine Model of Spinal Cord Ischemia-reperfusion

Background 
Lower extremity paralysis continues to complicate aortic interventions. The lack of understanding of the underlying pathology has hindered advancements to decrease the occurrence this injury.&#160;The current model demonstrates reproducible lower&#160;extremity paralysis following thoracic aortic occlusion.
Methods 
Adult male C57BL6 mice were anesthetized with isoflurane. Through a cervicosternal incision the aorta was exposed. The descending thoracic aorta and left subclavian arteries were identified without entrance into pleural space. Skeletonization of these arteries was followed by immediate closure (Sham) or occlusion for 4 min (moderate ischemia) or 8 min (prolonged ischemia). The sternotomy and skin were closed and the mouse was transferred to warming bed for recovery.&#160; Following recovery, functional analysis was obtained at 12 hr intervals until 48 hr.
Results 
Mice that underwent sham surgery showed no observable hind&#160;limb deficit. Mice subjected to moderate ischemia for 4 min had minimal functional deficit at 12 hr followed by progression to complete paralysis at 48 hr. Mice subjected to prolonged ischemia had an immediate paralysis with no observable hind-limb movement at any point in the postoperative period. There was no observed intraoperative or post&#160;operative mortality.
Conclusion 
Reproducible lower extremity paralysis whether immediate or delayed can be achieved in a murine model. Additionally, by using a median sternotomy and careful dissection, high survival rates, and reproducibility can be achieved.

The lack of mechanistic understanding of spinal cord ischemia-reperfusion injury has hindered further adjuncts to prevent paraplegia following high risk aortic operations. Thus, the development of animal models is imperative. This manuscript demonstrates reproducible lower extremity paralysis following thoracic aortic occlusion in a murine model.

Background
Lower extremity paralysis continues to complicate aortic interventions. The lack of understanding of the underlying pathology has hindered ...

Noninvasive Assessment of Cardiac Abnormalities in Experimental Autoimmune Myocarditis by Magnetic Resonance Microscopy Imaging in the Mouse

Myocarditis is an inflammation of the myocardium, but only ~10% of those affected show clinical manifestations of the disease. To study the immune events of myocardial injuries, various mouse models of myocarditis have been widely used. This study involved experimental autoimmune myocarditis (EAM) induced with cardiac myosin heavy chain (Myhc)-&#945; 334-352 in A/J mice; the affected animals develop lymphocytic myocarditis but with no apparent clinical signs. In this model, the utility of magnetic resonance microscopy (MRM) as a non-invasive modality to determine the cardiac structural and functional changes in animals immunized with Myhc-&#945; 334-352 is shown. EAM and healthy mice were imaged using a 9.4 T (400 MHz) 89 mm vertical core bore scanner equipped with a 4 cm millipede radio-frequency imaging probe and 100 G/cm triple axis gradients. Cardiac images were acquired from anesthetized animals using a gradient-echo-based cine pulse sequence, and the animals were monitored by respiration and pulse oximetry. The analysis revealed an increase in the thickness of the ventricular wall in EAM mice, with a corresponding decrease in the interior diameter of ventricles, when compared with healthy mice. The data suggest that morphological and functional changes in the inflamed hearts can be non-invasively monitored by MRM in live animals. In conclusion, MRM offers an advantage of assessing the progression and regression of myocardial injuries in diseases caused by infectious agents, as well as response to therapies.

This study demonstrates the successful establishment of magnetic resonance microscopy imaging as a non-invasive tool to assess the cardiac abnormalities in mice affected with autoimmune myocarditis. The data indicate that the technique can be used to monitor the disease-progression in live animals.

Myocarditis is an inflammation of the myocardium, but only ~10% of those affected show clinical manifestations of the disease. To study the immune events ...

Evaluation of Tumor-infiltrating Leukocyte Subsets in a Subcutaneous Tumor Model

Specialized immune cells that infiltrate the tumor microenvironment regulate the growth and survival of neoplasia.&#160; Malignant cells must elude or subvert anti-tumor immune responses in order to survive and flourish. Tumors take advantage of a number of different mechanisms of immune &#8220;escape,&#8221; including the recruitment of tolerogenic DC, immunosuppressive regulatory T cells (Tregs), and myeloid-derived suppressor cells (MDSC) that inhibit cytotoxic anti-tumor responses. Conversely, anti-tumor effector immune cells can slow the growth and expansion of malignancies: immunostimulatory dendritic cells, natural killer cells which harbor innate anti-tumor immunity, and cytotoxic T cells all can participate in tumor suppression. The balance between pro- and anti-tumor leukocytes ultimately determines the behavior and fate of transformed cells; a multitude of human clinical studies have borne this out. Thus, detailed analysis of leukocyte subsets within the tumor microenvironment has become increasingly important. Here, we describe a method for analyzing infiltrating leukocyte subsets present in the tumor microenvironment in a mouse tumor model. Mouse B16 melanoma tumor cells were inoculated subcutaneously in C57BL/6 mice. At a specified time, tumors and surrounding skin were resected en bloc and processed into single cell suspensions, which were then stained for multi-color flow cytometry. Using a variety of leukocyte subset markers, we were able to compare the relative percentages of infiltrating leukocyte subsets between control and chemerin-expressing tumors. Investigators may use such a tool to study the immune presence in the tumor microenvironment and when combined with traditional caliper size measurements of tumor growth, will potentially allow them to elucidate the impact of changes in immune composition on tumor growth. Such a technique can be applied to any tumor model in which the tumor and its microenvironment can be resected and processed.

This protocol describes a method for the detailed evaluation of leukocyte subsets within the tumor microenvironment in a mouse tumor model. Chemerin-expressing B16 melanoma cells were implanted subcutaneously into syngeneic mice. Cells from the tumor microenvironment were then stained and analyzed by flow cytometry, allowing for detailed leukocyte subset analyses.

Specialized immune cells that infiltrate the tumor microenvironment regulate the growth and survival of neoplasia.&#160; Malignant cells must elude or ...

Evaluation of Lung Metastasis in Mouse Mammary Tumor Models by Quantitative Real-time PCR

Metastatic disease is the spread of malignant tumor cells from the primary cancer site to a distant organ and is the primary cause of cancer associated death 1. Common sites of metastatic spread include lung, lymph node, brain, and bone 2. Mechanisms that drive metastasis are intense areas of cancer research. Consequently, effective assays to measure metastatic burden in distant sites of metastasis are instrumental for cancer research. Evaluation of lung metastases in mammary tumor models is generally performed by gross qualitative observation of lung tissue following dissection. Quantitative methods of evaluating metastasis are currently limited to ex vivo and in vivo imaging based techniques that require user defined parameters. Many of these techniques are at the whole organism level rather than the cellular level 3-6. Although newer imaging methods utilizing multi-photon microscopy are able to evaluate metastasis at the cellular level 7, these highly elegant procedures are more suited to evaluating mechanisms of dissemination rather than quantitative assessment of metastatic burden. Here, a simple in vitro method to quantitatively assess metastasis is presented. Using quantitative Real-time PCR (QRT-PCR), tumor cell specific mRNA can be detected within the mouse lung tissue.

This protocol describes how to use quantitative Real-time PCR (QRT-PCR) to detect tumor cell specific mRNA representing metastasis within the mouse lung tissue.

Metastatic disease is the spread of malignant tumor cells from the primary cancer site to a distant organ and is the primary cause of cancer associated ...

Reproducible Arterial Denudation Injury by Infrarenal Abdominal Aortic Clamping in a Murine Model

Percutaneous vascular interventions uniformly result in arterial denudation injuries that subsequently lead to thrombosis and restenosis. These complications can be attributed to impairments in re-endothelialization within the wound margins. Yet, the cellular and molecular mechanisms of re-endothelialization remain to be defined. While several animal models to study re-endothelialization after arterial denudation are available, few are performed in the mouse because of surgical limitations. This undermines the opportunity to exploit transgenic mouse lines and investigate the contribution of specific genes to the process of re-endothelialization. Here, we present a step-by-step protocol for creating a highly reproducible murine model of arterial denudation injury in the infrarenal abdominal aorta using external vascular clamping. Immunocytochemical staining of injured aortas for fibrinogen and &#946;-catenin demonstrate the exposure of a pro-thrombotic surface and the border of intact endothelium, respectively. The method presented here has the advantages of speed, excellent overall survival rate, and relative technical ease, creating a uniquely practical tool for imposing arterial denudation injury in transgenic mouse models. Using this method, investigators may elucidate the mechanisms of re-endothelialization under normal or pathological conditions.

Understanding the cellular and molecular mechanisms of re-endothelialization following arterial denudation injury is of paramount importance in preventing thrombosis and restenosis of arteries. Here we describe a protocol for reproducible arterial denudation injury of the infrarenal abdominal aorta. The procedure was developed to investigate the underlying mechanisms that regulate endothelial regeneration using mouse models.

Percutaneous vascular interventions uniformly result in arterial denudation injuries that subsequently lead to thrombosis and restenosis. These ...

Construction and Evaluation of a Murine Calvarial Osteolysis Model by Exposure to CoCrMo Particles in Aseptic Loosening

Wear particle-induced osteolysis is a major cause of aseptic loosening in arthroplasty failure, but the underlying mechanism remains unclear. Due to long follow-ups necessary for detection and sporadic occurrence, it is challenging to assess the pathogenesis ofparticle-induced osteolysis in clinical cases. Hence, optimal animal models are required for further studies. The murine model of calvarial osteolysis established by exposure to CoCrMo particles is an effective and valid tool for assessing the interactions between particles and various cells in aseptic loosening. In this model, CoCrMo particles were first obtained by high-vacuum three-electrode direct current and resuspended in phosphate-buffered saline at a concentration of 50 mg/mL. Then, 50 &#181;L of the resulting suspension was applied to the middle of the murine calvaria after separation of the cranial periosteum by sharp dissection. After two weeks, the mice were sacrificed, and calvaria specimens were harvested; qualitative and quantitative evaluations were performed by hematoxylin and eosin staining and micro computed tomography. The strengths of this model include procedure simplicity, quantitative evaluation of bone loss, rapidity of osteolysis development, potential use transgenic or knockout models, and a relatively low cost. However, this model cannot to be used to assess the mechanical force and chronic effects of particles in aseptic loosening. Murine calvarial osteolysis model generated by exposure to CoCrMo particles is an ideal tool for assessing the interactions between wear particles and various cells, e.g., macrophages, fibroblasts, osteoblasts and osteoclasts, in aseptic loosening.

This manuscript describes a murine calvarial osteolysis model by exposure to CoCrMo particles, which constitutes an ideal animal model for assessing the interactions between wear particles and various cells in aseptic loosening.

Wear particle-induced osteolysis is a major cause of aseptic loosening in arthroplasty failure, but the underlying mechanism remains unclear. Due to long ...