Name: echocardiographic and histological examination of cardiac morphology in the mouse
Uploaded: 2017-10-26T12:30:00
Description: Watch this Scientific Journal Video about Echocardiographic and Histological Examination of Cardiac Morphology in the Mouse at JoVE.com

The work was supported by the French Government (National Research Agency, ANR) through the &#34;Investments for the Future&#34; LABEX SIGNALIFE program (reference ANR-11-LABX-0028-01) and by grants to K. D. W. from the Association pour la Recherche sur le Cancer, Fondation de France, and Plan Cancer Inserm. D. B. and A. V. received fellowships from the Fondation pour la Recherche M&#233;dicale and from the City of Nice, respectively. The echocardiograph and the transducer were kindly provided by Philips. We thank A. Borderie, S. Destree, M. Cutajar-Bossert, A. Landouar, A. Martres, A. Biancardini, and S. M. Wagner for their skilled technical assistance.

The experiments described here were carried out in compliance with the relevant institutional and French animal welfare laws, guidelines, and policies. They have been approved by the French ethics committee (Comit&#233; Institutionnel d&#39;Ethique Pour l&#39;Animal de Laboratoire; number NCE/2012-106).
1. Echocardiography
<ol>
	<li>Determine the body weight of the mouse using a standard laboratory balance while holding it lightly by the tail to ensure proper positioning.</li>
	<li>Anestheti...

<ol>
	<li>Ormandy, E. H., Dale, J., Griffin, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetic+engineering+of+animals:+ethical+issues,+including+welfare+concerns.">Genetic engineering of animals: ethical issues, including welfare concerns.</a> Can Vet J. 52 (5), 544-550 (2011).</li><li>Karl, T., Pabst, R., von H&#246;rsten, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Behavioral+phenotyping+of+mice+in+pharmacological+and+toxicological+research.">Behavioral phenotyping of mice in pharmacological and toxicological research.</a> Exp Toxicol Pathol. 55 (1), 69-83 (2003).</li><li>Phoon, C. K., Turnbull, D. 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Different methods have been developed to evaluate cardiac structure and function in mice, including echocardiography, contrast-enhanced MRI, micro CT, and PET scan. Due to its cost-effectiveness and simplicity, echocardiography is the most widely used technique for functional analysis in mice11. In general, because of the small size of the heart and the high frequency of the heart rate in mice, transducers with a frequency &#62;10 MHz should be used, although successful measurements have been repo...

A large variety of genetically modified mouse models are available, and the number of pharmacological studies in mice is high1,2. Echocardiography and MRI are commonly used approaches for the phenotypic characterization of cardiac function and morphology in these mouse models3. The aim of the presented protocol is to analyze cardiac function and morphology in adult mice. It combines echocardiographic, histological, and immunohistochemical measurements. Echocardiographic examination is widely used in mice4,5,6,7,8,9,10,11,12. Pachon et al.11 identified 205 studies published in Circulation, Circulation Research, American Journal of Physiology - Heart and Circulatory Physiology, and Cardiovascular Research between 2012 and 2015 that used echocardiographic examination in animals.
Echocardiography is used to identify cardiac phenotypes in genetically modified mice5,6,13,14,15,16,17,18,19,20,21,22, as well as to analyze cardiac function in chronic overload-induced hypertrophy, myocardial ischemia, and cardiomyopathy models in mice (reviewed in12). Improved echocardiography equipment allows for the the standard measure of left-ventricular (LV) systolic and diastolic dimensions, tissue Doppler imaging, myocardial contrast echography, and the assessment of LV regional function and coronary reserve12. Ideally, echocardiographic examination should be performed in conscious mice to avoid the negative effects of anesthesia on contractile function, autonomic reflex control, and heart rate11. Nevertheless, this approach is limited by the requirement to train the animals; difficulties in keeping the body temperature stable; movement artifacts; stress; very high cardiac frequencies; and the requirement for at least two investigators to perform the experiment, especially if a large number of animals are under investigation. Interestingly, a recent study reported no differences in echocardiographic parameters in trained and untrained animals19. We perform echocardiographic measurements in anesthetized mice. Different anesthesia protocols will be discussed below.
Although standard resolution echocardiography (&#62;10 MHz) is sufficient to measure LV systolic and diastolic dimensions and cardiac function in adult mice, the method is limited in its description of underlying structural phenomena. Thus, we combine the in vivo measurements with histological and immunohistological analyses to measure, for example, cardiomyocyte diameter and vessel density. Other histological and immunohistological investigations, such as the determination of proliferation, examination of apoptosis, infarct size measurements, determination of fibrosis, and specific marker expression, can also be performed on the same type of processed tissue but are not the subject of this protocol. The combination of in vivo echocardiographic examination with histological analyses provides additional insights into underlying structural alterations. In an additional step, we can complete these measurements with molecular and ultra-structural investigations. Histological analyses not only complete the echocardiographic examination but also become indispensible when the resolution of echocardiography is not sufficient. This is especially the case in models of genetically modified mice that are embryonic lethal23,24.

<table>
	<tbody>
		<tr>
			<td>Wheat germ agglutinin (WGA) conjugated tetramethylrhodamine</td>
			<td>Life Technologies, Molecular Probes</td>
			<td>W849</td>
			<td></td>
		</tr>
		<tr>
			<td>Biotinylated Goat Anti-Rabbit IgG Antibody</td>
			<td>Vectorlabs</td>
			<td>BA-1000</td>
			<td></td>
		</tr>
		<tr>
			<td>Avidin/Biotin Blocking Kit</td>
			<td>Vectorlabs</td>
			<td>SP-2001</td>
			<td></td>
		</tr>
		<tr>
			<td>VECTASTAIN Elite ABC HRP Kit (Peroxidase, Standard)</td>
			<td>Vectorlabs</td>
			<td>PK-6100</td>
			<td></td>
		</tr>
		<tr>
			<td>VECTASHIELD Antifade Mounting Medium with DAPI</td>
			<td>Vectorlabs</td>
			<td>H-1200</td>
			<td></td>
		</tr>
		<tr>
			<td>SIGMAFAST 3,3&#39;-Diaminobenzidine tablets</td>
			<td>Sigma</td>
			<td>D4168</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrogen peroxide solution</td>
			<td>Sigma</td>
			<td>H1009</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-Pecam-1 (CD31) antibody</td>
			<td>Abcam</td>
			<td>ab28364</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultrasound transmission gel, Gel Aquasonic 100</td>
			<td>Parker</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Linear ultrasound probe, L15-7io</td>
			<td>Philips Healthcare</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Echocardiograph, IE33 xMATRIX</td>
			<td>Philips Healthcare</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope, Leica DMi8</td>
			<td>Leica</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescence Filterset DAPI</td>
			<td>Leica</td>
			<td>11525304</td>
			<td></td>
		</tr>
		<tr>
			<td>Filterset TxR</td>
			<td>Leica</td>
			<td>11525310</td>
			<td></td>
		</tr>
		<tr>
			<td>Digital Camera, SPOT RT3 Color Slider</td>
			<td>Spot Imaging</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Imaging Software, SPOT 5.2 Advanced and Basic Software</td>
			<td>Spot Imaging</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Imaging Computer</td>
			<td>Dell</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Fine Scissors</td>
			<td>Fine Science Tools</td>
			<td>14028-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Large Scissors</td>
			<td>Fine Science Tools</td>
			<td>14501-14</td>
			<td></td>
		</tr>
		<tr>
			<td>Scalpel blades</td>
			<td>Fine Science Tools</td>
			<td>10023-00</td>
			<td></td>
		</tr>
		<tr>
			<td>Graefe Forceps</td>
			<td>Fine Science Tools</td>
			<td>11650-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Rodent shaver</td>
			<td>Harvard Apparatus</td>
			<td>34-0243</td>
			<td></td>
		</tr>
		<tr>
			<td>cassettes for paraffin embedding</td>
			<td>Sakura</td>
			<td>4155F</td>
			<td></td>
		</tr>
		<tr>
			<td>neutral buffered Formalin</td>
			<td>Sakura</td>
			<td>8727</td>
			<td></td>
		</tr>
		<tr>
			<td>Xylene</td>
			<td>Sakura</td>
			<td>8733</td>
			<td></td>
		</tr>
		<tr>
			<td>Paraffine TEK III</td>
			<td>Sakura</td>
			<td>4511</td>
			<td></td>
		</tr>
		<tr>
			<td>automated embedding apparatus, Tissue-Tek VIP</td>
			<td>Sakura</td>
			<td>6032</td>
			<td></td>
		</tr>
		<tr>
			<td>paraffin-embedding station Tissue-Tek TEC 5</td>
			<td>Sakura</td>
			<td>5229</td>
			<td></td>
		</tr>
		<tr>
			<td>microtome blades,Accu-Edge S35</td>
			<td>Sakura</td>
			<td>4685</td>
			<td></td>
		</tr>
		<tr>
			<td>microscopy slides, Tissue-Tek</td>
			<td>Sakura</td>
			<td>9533</td>
			<td></td>
		</tr>
		<tr>
			<td>cover slips, Tissue-Tek</td>
			<td>Sakura</td>
			<td>9582</td>
			<td></td>
		</tr>
		<tr>
			<td>Mounting medium Tissue-Tek</td>
			<td>Sakura</td>
			<td>1408</td>
			<td></td>
		</tr>
		<tr>
			<td>slide boxes</td>
			<td>Sakura</td>
			<td>3958</td>
			<td></td>
		</tr>
		<tr>
			<td>eosine solution</td>
			<td>Sakura</td>
			<td>8703</td>
			<td></td>
		</tr>
		<tr>
			<td>hematoxyline solution</td>
			<td>Sakura</td>
			<td>8711</td>
			<td></td>
		</tr>
		<tr>
			<td>microtome, RM2125RT</td>
			<td>Leica</td>
			<td>720-1880 (VWR)</td>
			<td></td>
		</tr>
		<tr>
			<td>water bath, Leica HI1210</td>
			<td>Leica</td>
			<td>720-0113(VWR)</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>VWR</td>
			<td>ACRO444220050</td>
			<td></td>
		</tr>
		<tr>
			<td>15 ml tubes</td>
			<td>VWR</td>
			<td>734-0451</td>
			<td></td>
		</tr>
		<tr>
			<td>staining glass dish</td>
			<td>VWR</td>
			<td>MARI4220004</td>
			<td></td>
		</tr>
		<tr>
			<td>staining jars</td>
			<td>VWR</td>
			<td>MARI4200005</td>
			<td></td>
		</tr>
		<tr>
			<td>Incubator</td>
			<td>Binder</td>
			<td>9010-0012</td>
			<td></td>
		</tr>
		<tr>
			<td>DAB and urea hydrogen peroxide tablets, SIGMAFAST 3,3&#8242;-Diaminobenzidine tablets</td>
			<td>Sigma</td>
			<td>D4293</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS (10X)</td>
			<td>Thermo Fisher Scientific</td>
			<td>70011044</td>
			<td></td>
		</tr>
	</tbody>
</table>

echocardiographic and histological examination of cardiac morphology in the mouse

An increasing number of genetically modified mouse models has become available in recent years. Moreover, the number of pharmacological studies performed in mice is high. Phenotypic characterization of these mouse models also requires the examination of cardiac function and morphology. Echocardiography and magnetic resonance imaging (MRI) are commonly used approaches to characterize cardiac function and morphology in mice. Echocardiographic and MRI equipment specialized for use in small rodents is&#160;expensive and requires a dedicated space. This protocol describes cardiac measurements in mice using a clinical echocardiographic system with a 15 MHz human vascular probe. Measurements are performed on anesthetized adult mice. At least three image sequences are recorded and analyzed for each animal in M-mode in the parasternal short-axis view. Afterwards, cardiac histological examination is performed, and cardiomyocyte diameters are determined on hematoxylin-eosin- or wheat germ agglutinin (WGA)-stained paraffin sections. Vessel density is determined morphometrically after Pecam-1 immunostaining. The protocol has been applied successfully to pharmacological studies and different genetic animal models under baseline conditions, as well as after experimental myocardial infarction by the permanent ligation of the left anterior descending coronary artery (LAD). In our experience, echocardiographic investigation is limited to anesthetized animals and is feasible in adult mice weighing at least 25 g.

In Figure 1, representative echocardiographic recordings demonstrate the usefulness of echocardiography to identify cardiac phenotypes in genetically modified mice. The difference between a mouse with normal cardiac function (Figure 1A) and an animal with a dilated left ventricle and reduced LV function (Figure 1B) can easily be identified. Figure 2 shows the comparison ...

Watch this Scientific Journal Video about Echocardiographic and Histological Examination of Cardiac Morphology in the Mouse at JoVE.com

Echocardiographic and Histological Examination of Cardiac Morphology in the Mouse

Echocardiographic examination is frequently used in mice. Expensive high-resolution ultrasound devices have been developed for this purpose. This protocol describes an affordable echocardiographic procedure combined with histological morphometric analyses to determine cardiac morphology.

An increasing number of genetically modified mouse models has become available in recent years. Moreover, the number of pharmacological studies performed ...

The overall goal of this echocardiographic examination combined with histological investigations is to examine cardiac function and morphology in different transgenic mouse models under baseline and pathophysiological conditions. To begin, while lightly holding a mouse by it's tail, use a standard laboratory balance to determine the body weight of the animal. After anesthetizing the mouse according to the text protocol lightly squeeze a rear foot and observe if the leg retracts.Use a commercial rodent shaver to shave the left side of the thorax and the left armpit. Position the animal on a warm pad set at 40 to 42 degrees Celsius in a shallow left sided position, with the head at 12 o'clock and the tail at 6 o'clock. Then use tape to fix the left arm, left leg and tail.Apply pre-warmed echocardiography gel onto the shaved chest and the head of the transducer. Next place the echocardiograph transducer parasternal left, directing it to the right side of the neck to obtain a two-dimensional parasternal long access view on the level of the papillary muscle. Then turn the transducer 90 degrees clockwise to obtain a short access view.Establish a minimal depth setting and a zoom to maximize image quality and frame rate. Set the sweep speed to the maximum. Record 2-D guided M-mode images in short access view.Record at least three series of three heartbeat semiloops for each animal. After obtaining successful recordings, remove the tape from the limbs and tail. Wipe off the echocardiogrpahy gel from the mouse thorax heating pad and transducer.Leave the mouse under observation on the heating pad, covered with tissue to avoid unnecessary light exposure and heat loss until it wakes up. Then put the animal back in the cage. Analyze recorded M-mode images from short access view to determine left ventricular or LV dimensions and function.Using the identification of the tissue blood interface on the stored images, measure the thickness of the LV anterior wall in systole and diastole, the LV internal end-systolic and end-diastolic diameters, and the LV posterior wall thickness in systole and diastole. Measure the diastolic dimensions at the time of the apparent maximal LV diastolic dimensions and the LV end-systolic dimensions at the end of the most anterior systolic excursion of the LV posterior wall. Tap the touchscreen on the analyze icon and then on the LVAWd icon.Position the electronic caliper on the interface between the right ventricular cavity and the LV anterior wall in diastole. Next position the electronic caliper on the interface between the LV anterior wall and the LV cavity to obtain LV diastolic anterior wall thickness. Position the caliper on the interface between the LV cavity and the LV posterior wall to obtain the LV internal and diastolic diameter.Position the caliper on the interface between the LV posterior wall and the pericardium to obtain the LV diastolic posterior wall thickness. For LV systolic dimensions, tap the touchscreen on the LVAWs icon and position the electronic caliper on the interface between the right ventricular cavity and the LV anterior wall in systole. Position the electronic caliper on the interface between the LV anterior wall and the LV cavity to obtain the LV systolic anterior wall thickness.Position the caliper on the interface between the LV cavity and the LV posterior wall to obtain the LV internal and systolic diameter. Position the caliper on the interface between the LV posterior wall and the pericardium to obtain the LV systolic posterior wall thickness. After sacrificing the animals according to the text protocol measure their body weights.Then use a 70%alcohol swab to disinfect the chest and abdomen. Make a transverse incision in the skin, one centimeter distal to the sternum. Then using blunt forceps, remove the skin from the thorax moving in the direction of the head.With fine forceps, hold the sternum lightly and open the diaphragm by inserting the blunt end of fine scissors. Cut the ribcage on both sides parallel to the sternum. Then move the sternum in the direction of the head.Locate the heart in the thorax. With fine forceps, hold the vascular trunk of the heart and use fine scissors to cut below the organ. Then measure the heart weight and establish a heart-to-body weight ratio.Transfer the heart into two milliliters of 10%neutral buffered Formalin solution in a 15 milliliter tube and fix the organ at four degrees Celsius overnight. To perform Wheat Germ Agglutinin or WGA staining, place the previously prepared slides in Tetramethylrhodamine conjugated WGA and incubate the samples at room temperature in a humid chamber for sixty minutes. Use PBS to wash the samples three times for five minutes each.Then use fluorescence mounting medium contained DAPI to mount the sections. Store them at four degrees Celsius in the dark before analysis. These representative echocardiographic recordings demonstrate the usefulness of echocardiography to identify cardiac phenotypes in genetically modified mice.The difference between a mouse with normal cardiac function and an animal with a dilated left ventricle or LV and reduced LV function can easily be identified. Shown here is a comparison of cardiomyocyte diameter measurements in animals without and with cardiac hypertrophy using H&E stained paraffin heart sections and measurements of longitudinal sections of heart tissue. This figure illustrates the measurement of cardiomyocyte transverse diameters using WGA stained paraffin sections from hearts of control mice and animals with cardiac hypertrophy.These panels depict the utility of PECAM1 Immunohistochemistry of cardiac sections to determine the vessel density of normal heart tissue and hearts with increased angiogenesis.

echocardiographic-histological-examination-cardiac-morphology

Research

JoVE Journal

Medicine

Assessment of Cardiac Function and Myocardial Morphology Using Small Animal Look-locker Inversion Recovery (SALLI) MRI in Rats

Small animal magnetic resonance imaging is an important tool to study cardiac function and changes in myocardial tissue. The high heart rates of small animals (200 to 600 beats/min) have previously limited the role of CMR imaging. Small animal Look-Locker inversion recovery (SALLI) is a T1 mapping sequence for small animals to overcome this problem 1. T1 maps provide quantitative information about tissue alterations and contrast agent kinetics. It is also possible to detect diffuse myocardial processes such as interstitial fibrosis or edema 1-6. Furthermore, from a single set of image data, it is possible to examine heart function and myocardial scarring by generating cine and inversion recovery-prepared late gadolinium enhancement-type MR images 1.
	The presented video shows step-by-step the procedures to perform small animal CMR imaging. Here it is presented with a healthy Sprague-Dawley rat, however naturally it can be extended to different cardiac small animal models.

Assessment of Cardiac Function and Myocardial Morphology Using Small Animal Look-locker Inversion Recovery SALLI MRI in Rats

Contrast enhanced cardiac magnetic resonance (CMR) imaging allows comprehensive in vivo assessment of the heart in small animal models of cardiovascular disease. Here we detail the procedures to perform CMR imaging, reconstruction and analysis using Small Animal Lock-Locker Inversion Recovery (SALLI) in rats.

Small animal magnetic resonance  imaging is an important tool to study cardiac function and changes in myocardial  tissue. The high heart rates of small ...

Technical Aspects of the Mouse Aortocaval Fistula

Technical aspects of creating an arteriovenous fistula in the mouse are discussed. Under general anesthesia, an abdominal incision is made, and the aorta and inferior vena cava (IVC) are exposed. The proximal infrarenal aorta and the distal aorta are dissected for clamp placement and needle puncture, respectively. Special attention is paid to avoid dissection between the aorta and the IVC. After clamping the aorta, a 25 G needle is used to puncture both walls of the aorta into the IVC. The surrounding connective tissue is used for hemostatic compression. Successful creation of the AVF will show pulsatile arterial blood flow in the IVC. Further confirmation of successful AVF can be achieved by post-operative Doppler ultrasound.

The goal is to produce an arteriovenous fistula that is simple and reproducible. This method does not use sutures or glue adhesive. Therefore the samples can be used with the least amount of foreign materials for analysis.

Technical aspects of creating an arteriovenous fistula in the mouse are discussed. Under general anesthesia, an abdominal incision is made, and the aorta ...

Echocardiographic Assessment of the Right Heart in Mice

Transgenic and toxic models of pulmonary arterial hypertension (PAH) are widely used to study the pathophysiology of PAH and to investigate potential therapies. Given the expense and time involved in creating animal models of disease, it is critical that researchers have tools to accurately assess phenotypic expression of disease. Right ventricular dysfunction is the major manifestation of pulmonary hypertension. Echocardiography is the mainstay of the noninvasive assessment of right ventricular function in rodent models and has the advantage of clear translation to humans in whom the same tool is used. Published echocardiography protocols in murine models of PAH are lacking.
In this article, we describe a protocol for assessing RV and pulmonary vascular function in a mouse model of PAH with a dominant negative BMPRII mutation; however, this protocol is applicable to any diseases affecting the pulmonary vasculature or right heart. We provide a detailed description of animal preparation, image acquisition and hemodynamic calculation of stroke volume, cardiac output and an estimate of pulmonary artery pressure.

This article provides a protocol for the echocardiographic assessment of right ventricular size and pulmonary hypertension in mice. Applications include phenotype determination and serial assessment in transgenic and toxin-induced mouse models of cardiomyopathy and pulmonary vascular disease.

Transgenic and toxic models of pulmonary arterial hypertension (PAH) are widely used to study the pathophysiology of PAH and to investigate potential ...

Visualization of Streptococcus pneumoniae within Cardiac Microlesions and Subsequent Cardiac Remodeling

During bacteremia Streptococcus pneumoniae can translocate across the vascular endothelium into the myocardium and form discrete bacteria-filled microscopic lesions (microlesions) that are remarkable due to the absence of infiltrating immune cells. Due to their release of cardiotoxic products, S. pneumoniae within microlesions are thought to contribute to the heart failure that is frequently observed during fulminate invasive pneumococcal disease in adults. Herein is demonstrated a protocol for experimental mouse infection that leads to reproducible cardiac microlesion formation within 30 hr. Instruction is provided on microlesion identification in hematoxylin &#38; eosin stained heart sections and the morphological distinctions between early and late microlesions are highlighted. Instruction is provided on a protocol for verification of S. pneumoniae within microlesions using antibodies against pneumococcal capsular polysaccharide and immunofluorescent microscopy. Last, a protocol for antibiotic intervention that rescues infected mice and for the detection and assessment of scar formation in the hearts of convalescent mice is provided. Together, these protocols will facilitate the investigation of the molecular mechanisms underlying pneumococcal cardiac invasion, cardiomyocyte death, cardiac remodeling as a result of exposure to S. pneumoniae, and the immune response to the pneumococci in the heart.

Visualization of Streptococcus pneumoniae within Cardiac Microlesions and Subsequent Cardiac Remodeling

Streptococcus pneumoniae forms discrete non-purulent microscopic lesions in the heart. Outlined is the protocol for a murine model of cardiac microlesion formation. Instruction is provided on microlesion visualization using microscopy, discrimination between early and late microlesions, and methods to detect cardiac remodeling in hearts of convalescent animals.

During bacteremia Streptococcus pneumoniae can translocate across the vascular endothelium into the myocardium and form discrete bacteria-filled ...

Do's and Don'ts in the Preparation of Muscle Cryosections for Histological Analysis

Histological evaluation of muscle biopsies has served as an indispensable tool in the understanding of the development and progression of pathology of neuromuscular disorders. However, in order to do so, proper care needs to be taken when excising and preserving tissues to achieve optimal staining. One method of tissue preservation involves fixing tissues in formaldehyde and then embedding them with paraffin wax. This method preserves morphology well and allows for long-term storage at RT but is cumbersome and requires handling of toxic chemicals. Further, formaldehyde fixation results in antigen cross-linking, which necessitates antigen retrieval protocols for effective immunostaining. On the contrary, frozen sectioning does not require fixation and thus retains biological antigen conformation. This method also provides a distinct advantage in quick turn around time, making it especially useful in situations needing quick histological evaluation like intraoperative surgical biopsies. Here we describe the most effective method of preparing muscle biopsies for visualization with different histological and immunological stains.

Here we demonstrate the most efficient methods for freezing, embedding, cryosectioning, and staining of muscle biopsies to avoid freezing artifacts.

Histological evaluation of muscle biopsies has served as an indispensable tool in the understanding of the development and progression of pathology of ...

Assessment of Cardiac Morphological and Functional Changes in Mouse Model of Transverse Aortic Constriction by Echocardiographic Imaging

Transverse aortic constriction (TAC) in mice has been used as a valuable model to study mechanisms of cardiac hypertrophy and heart failure1. A reliable noninvasive method is essential to assess real-time cardiac morphological and functional changes in animal models of heart disease. Transthoracic echocardiography represents an important tool for noninvasive assessment of cardiac structure and function2. Here we used a high-resolution ultrasound imaging system to monitor myocardial remodeling and heart failure progression over time in a mouse model of TAC. B-mode, M-mode, and Doppler imaging were used to precisely assess cardiac hypertrophy, ventricular dilatation, and functional deterioration in mice following TAC. Color and pulse wave (PW) Doppler imaging was used to noninvasively measure pressure gradient across the aortic constriction created by TAC and to assess transmitral blood flow in mice. Thus transthoracic echocardiographic imaging provides comprehensive noninvasive measurements of cardiac dimensions and function in mouse models of heart disease.

The goal of this protocol is to noninvasively assess cardiac structural and functional changes in a mouse model of heart disease created by transverse aortic constriction, using B- and M-mode echocardiography and color/pulse wave Doppler imaging.

Transverse aortic constriction (TAC) in mice has been used as a valuable model to study mechanisms of cardiac hypertrophy and heart failure1. A reliable ...

Dissection of the Mouse Pancreas for Histological Analysis and Metabolic Profiling

We have been investigating the pancreas specific transcription factor, 1a cre-recombinase; lox-stop-lox- Kristen rat sarcoma, glycine to aspartic acid at the 12 codon (Ptf1acre/+;LSL-KrasG12D/+) mouse strain as a model of human pancreatic cancer. The goal of our current studies is to identify novel metabolic biomarkers of pancreatic cancer progression. We have performed metabolic profiling of urine, feces, blood, and pancreas tissue extracts, as well as histological analyses of the pancreas to stage the cancer progression. The mouse pancreas is not a well-defined solid organ like in humans, but rather is a diffusely distributed soft tissue that is not easily identified by individuals unfamiliar with mouse internal anatomy or by individuals that have little or no experience performing mouse organ dissections. The purpose of this article is to provide a detailed step-wise visual demonstration to guide novices in the removal of the mouse pancreas by dissection. This article should be especially valuable to students and investigators new to research that requires harvesting of the mouse pancreas by dissection for metabolic profiling or histological analyses.

This video article provides a detailed demonstration of the procedures required to successfully remove the pancreas from a mouse by dissection for histological analysis and metabolic profiling.

We have been investigating the pancreas specific transcription factor, 1a cre-recombinase; lox-stop-lox- Kristen rat sarcoma, glycine to aspartic acid at ...

Cardiac Magnetic Resonance Imaging at 7 Tesla

CMR at an ultra-high field (magnetic field strength B0&#160;&#8805; 7 Tesla) benefits from the signal-to-noise ratio (SNR) advantage inherent at higher magnetic field strengths and potentially provides improved signal contrast and spatial resolution. While promising results have been achieved, ultra-high field CMR is challenging due to energy deposition constraints and physical phenomena such as transmission field non-uniformities and magnetic field inhomogeneities. In addition, the magneto-hydrodynamic effect renders the synchronization of the data acquisition with the cardiac motion difficult. The challenges are currently addressed by explorations into novel magnetic resonance technology. If all impediments can be overcome, ultra-high field CMR may generate new opportunities for functional CMR, myocardial tissue characterization, microstructure imaging or metabolic imaging. Recognizing this potential, we show that multi-channel radio frequency (RF) coil technology tailored for CMR at 7 Tesla together with higher order B0 shimming and a backup signal for cardiac triggering facilitates high fidelity functional CMR. With the proposed setup, cardiac chamber quantification can be accomplished in examination times similar to those achieved at lower field strengths. To share this experience and to support the dissemination of this expertise, this work describes our setup and protocol tailored for functional CMR at 7 Tesla.

The sensitivity gain inherent to ultrahigh field magnetic resonance holds promise for high spatial resolution imaging of the heart. Here, we describe a protocol customized for functional cardiovascular magnetic resonance (CMR) at 7 Tesla using an advanced multi-channel radio-frequency coil, magnetic field shimming and a triggering concept.

CMR at an ultra-high field (magnetic field strength B0&#160;&#8805; 7 Tesla) benefits from the signal-to-noise ratio (SNR) advantage inherent at higher ...

Semi-automated Analysis of Mouse Skeletal Muscle Morphology and Fiber-type Composition

For years, distinctions between skeletal muscle fiber types were best visualized by myosin-ATPase staining. More recently, immunohistochemical staining of myosin heavy chain (MyHC) isoforms has emerged as a finer discriminator of fiber-type. Type I, type IIA, type IIX and type IIB fibers can now be identified with precision based on their MyHC profile; however, manual analysis of these data can be slow and down-right tedious. In this regard, rapid, accurate assessment of fiber-type composition and morphology is a very desirable tool. Here, we present a protocol for state-of-the-art immunohistochemical staining of MyHCs in frozen sections obtained from mouse hindlimb muscle in concert with a novel semi-automated algorithm that accelerates analysis of fiber-type and fiber morphology. As expected, the soleus muscle displayed staining for type I and type IIA fibers, but not for type IIX or type IIB fibers. On the other hand, the tibialis anterior muscle was composed predominantly of type IIX and type IIB fibers, a small fraction of type IIA fibers and little or no type I fibers. Several image transformations were used to generate probability maps for the purpose of measuring different aspects of fiber morphology (i.e., cross-sectional area (CSA), maximal and minimal Feret diameter). The values obtained for these parameters were then compared with manually-obtained values. No significant differences were observed between either mode of analysis with regards to CSA, maximal or minimal Feret diameter (all p &#62; 0.05), indicating the accuracy of our method. Thus, our immunostaining analysis protocol may be applied to the investigation of effects on muscle composition in many models of aging and myopathy.

Immunohistochemical staining of myosin heavy chain isoforms has emerged as the state-of-the-art discriminator of skeletal muscle fiber-type (i.e., type I, type IIA, type IIX, type IIB). Here, we present a staining protocol along with a novel semi-automated algorithm that facilitates rapid assessment of fiber-type and fiber morphology.

For years, distinctions between skeletal muscle fiber types were best visualized by myosin-ATPase staining. More recently, immunohistochemical staining of ...

Echocardiographic Measurement of Right Ventricular Diastolic Parameters in Mouse

Diastolic dysfunction is a prominent feature of right ventricular (RV) remodeling associated with conditions of pressure overload. However, the RV diastolic function is rarely quantified in experimental studies. This might be due to technical difficulties in the visualization of the RV in the apical four-chamber view in rodents. Here we describe two positions facilitating the visualization of the apical four-chamber view in mice to assess the RV diastolic function.
The apical four-chamber view is enabled by tilting the mouse fixation platform to the left and caudally (LeCa) or to the right and cranially (RiCr). Both positions provide images of comparable quality. The results of the RV diastolic function obtained from two positions are not significantly different. Both positions are comparably easy to perform. This protocol can be incorporated into published protocols and enables detailed investigations of the RV function.

Here we describe and compare two positions for obtaining the apical four-chamber view in mice. These positions enable the quantification of the right ventricular function, provide comparable results, and can be used interchangeably.