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>Anesthetize the animal by the intraperitoneal (i.p.) injection of 50 mg/kg pentobarbital25,26. 
	NOTE: Any other kind of anesthesia can be used if the same protocol is used throughout the study. Advantages and disadvantages will be discussed below.</li>
	<li>Put the mouse back in its own cage and wait until it is unresponsive, it shows steady breathing, and rear foot reflexes are absent. To test this, squeeze a foot slightly and observe whether the leg still retracts.</li>
	<li>Shave the left side of the thorax and the left armpit using a commercial rodent shaver. 
	NOTE: The use of a dedicated rodent shaver allows for the complete removal of fine mouse hair to avoid interference in the echocardiographic measurement. Commercial hair removal creams or solutions should be avoided, as they are usually perfumed, which will disturb the animal after it awakens. Avoid excessive shaving, as it increases heat loss.</li>
	<li>Put the sleeping animal on a warm pad set to 40 - 42 &#176;C in a shallow left-sided position, with the head at 12 o&#39;clock and the tail at 6 o&#39;clock. Fix the left arm, left leg, and tail with tape.</li>
	<li>Apply pre-warmed echocardiography gel onto the shaved chest and the head of the transducer.</li>
	<li>Place the transducer parasternal-left, directing it to the right side of the neck to obtain a two-dimensional (2D) parasternal long-axis view on the level of the papillary muscle. Turn the transducer 90&#176; clockwise to obtain a short-axis view at papilary muscle level. Use a minimal depth setting and a zoom to maximize image quality and frame rate. Set the sweep speed to the maximum.
	<ol>
		<li>To obtain these settings, different zoom and depth setting options may be used, depending on the machine and software. Record 2D-guided M-mode images in short-axis view27. Refer to Figure 1A and B27. 
		NOTE: Take care to avoid applying excessive pressure to the chest, as this may cause bradycardia.</li>
	</ol>
	</li>
	<li>Record at least 3 series of 3 heart beat cine loops for each animal. 
	NOTE: For the echocardiograph software used in this study, press the &#34;Acquire/Save&#34; button only once. This methodology is specific to the echocardiograph with this particular software. Other software packages may be used with different machines.</li>
	<li>After successful recordings, wipe off the echocardiography gel from the mouse thorax, heating pad, and transducer. Remove the tape from the limbs and tail.</li>
	<li>Leave the mouse under observation on the heating pad, covered with tissue to avoid unnecessary light exposure and heat loss, until it wakes up.</li>
	<li>Put the animal back in its cage.</li>
	<li>Analyze recorded M-mode images from parasternal short-axis view to determine left ventricular (LV) dimensions and function. Measure the thickness of the LV anterior wall in systole and diastole (LVAWs and LVAWd), the LV internal end-systolic and end-diastolic diameters (LVIDs and LVIDd), and the LV posterior wall thickness (LVPW) in systole and diastole (LVPWs and LVPWd) using the identification of the tissue-blood interface on the stored images.</li>
	<li>Measure the diastolic dimensions at the time of the apparent maximal LV diastolic dimensions and LV end-systolic dimensions at the time of the most anterior systolic excursion of the LV posterior wall. Tap the touchscreen on the &#34;Analyze&#34; icon and then on the &#34;LVAWd&#34; icon. Position the electronic caliper on the interface between the right ventricular cavity and the LV anterior wall in diastole.</li>
	<li>Position the electronic caliper on the interface between the LV anterior wall and the LV cavity to obtain the LV diastolic anterior wall thickness; the software will directly switch to the LV internal end-diastolic measurement.</li>
	<li>Position the caliper on the interface between the LV cavity and the LV posterior wall to obtain the LV internal end-diastolic diameter; the software will switch to the LV posterior wall thickness measurement.</li>
	<li>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 touch screen on the &#34;LVAWs&#34; icon and position the electronic caliper on the interface between the right ventricular cavity and the LV anterior wall in systole.</li>
	<li>Position the electronic caliper on the interface between the LV anterior wall and the LV cavity to obtain the LV systolic anterior wall thickness. Repeat the process as described above for the LV internal end-systolic diameter and the LV systolic posterior wall thickness. Use the leading-edge convention adopted by the American Society of Echocardiography to trace the endocardial and epicardial borders13,27. 
	NOTE: LV contractile function parameters will be automatically calculated using the previous measurements. The LV fractional shortening (FS) is defined as FS (%) = [(LVIDd - LVIDs)/LVIDd] x 100. The LV ejection fraction (EF) is calculated with the modified Teicholz formula, where EF (%) = [(LVIDd3 - LVIDs3)/LVIDd3] x 10012. Refer to Figure 1A and B.</li>
	<li>Store the data on compact discs or USB memory sticks and make backup copies.</li>
	<li>Import, analyze, and export the data using the appropriate software. 
	NOTE: After these baseline measurements, the experiment can be paused. If performing a direct comparison between knockout animals and wild-type littermates, proceed with the histological analyses6. For Cre-ERT2; lox/lox mouse lines, continue the following day with tamoxifen induction by i.p. injection, as described5,24. If inducing experimental myocardial infarction by the ligation of the left coronary artery5,28, the surgery could be performed directly after the echocardiographic measurements, when the mice are under anesthesia. Otherwise, a minimum delay of one week between two rounds of anesthesia should be maintained to limit the rate of post-operative lethality.</li>
</ol>
2. Preparation of Heart Samples for Histological Evaluation
<ol>
	<li>Sacrifice the animals by cervical dislocation. Measure their body weights. Disinfect the&#160;chest and abdomen using a 70% alcohol swab.</li>
	<li>Make a transverse incision in the skin 1 cm distal to the sternum. Using blunt forceps, remove the skin from the thorax, moving in the direction of the head. Hold the sternum lightly with fine forceps and open the diaphragm by inserting the blunt end of fine scissors.</li>
	<li>Cut the rib cage on both sides parallel to the sternum. Move the sternum in the direction of the head. Locate the heart in the thorax. Hold the vascular trunk of the heart with the fine forceps and cut below using fine scissors.</li>
	<li>Open the chest and excise the entire heart out of the thorax, measure the heart weight, and establish a heart-to-body weight ratio4,5,6,23,29,30.</li>
	<li>Fix the heart in 2 mL of 10% neutral buffered formalin solution in 15-mL tubes overnight at 4 &#176;C. 
	CAUTION: Danger! Work with formalin solutions must be done in a chemical fume hood; wear gloves and safety glasses. 
	NOTE: As the buffer composition for formalin solutions varies with different suppliers, use the same supplier throughout the study.</li>
	<li>The next day, cut the hearts in the transverse plane, in the middle, and transfer them into cassettes for paraffin embedding, which is performed in the pathology laboratory using an automated embedding apparatus.</li>
	<li>Perform sectioning.
	<ol>
		<li>Section paraffin blocks at a thickness of 3 &#181;m using a microtome and float them in a 40 &#176;C water bath containing distilled water.</li>
		<li>Transfer the sections onto slides. Allow the slides to dry overnight in a 37 &#176;C incubator and store them at 4 &#176;C until ready for use. 
		NOTE: The protocol can be paused here until the user is ready for staining (step 3).</li>
	</ol>
	</li>
	<li>Deparaffinize and rehydrate the tissue slides.
	<ol>
		<li>Place the slides in staining jars with glass inserts in a 55 &#176;C oven for 10 min to melt the paraffin.</li>
		<li>Deparaffinize the slides in two changes of 200 mL of xylene or xylene substitute for 5 min each. 
		CAUTION: Highly flammable and toxic! Work in a chemical fume hood; wear gloves and safety glasses.</li>
		<li>Transfer the slides to 200 mL of 100% alcohol. Make two changes for 3 min each and transfer once through 200 mL of 95% alcohol for 3 min. 
		CAUTION: Highly flammable! Keep away from sources of ignition; no smoking.</li>
		<li>Rinse twice in 200 mL of phosphate-buffered saline solution (PBS) for 5 min each and continue with step 3, 4, or 5.</li>
	</ol>
	</li>
</ol>
3. Hematoxylin and Eosin Staining
<ol>
	<li>Rinse the slides with their sections in distilled water.</li>
	<li>Stain the nuclei with hematoxylin solution for 8 min.</li>
	<li>Rinse in running tap water for 10 min.</li>
	<li>Stain with eosin solution for 2 min.</li>
	<li>Dehydrate three times for 2 min in 100% ethanol (EtOH). Clear three times for 2 min in xylene or xylene substitute. Mount in a xylene-based mounting medium.</li>
	<li>Photograph the slides and measure the cardiomyocyte diameter at the level of the nucleus in longitudinal sections of the interventricular septum. Measure at least 100 cells per section and three sections per heart.</li>
</ol>
4. WGA Staining
<ol>
	<li>Incubate the slides obtained from step 2.7 with tetramethylrhodamine (or other fluorescent dyes)-conjugated WGA (1:100 in PBS) for 60 min at room temperature in a humid chamber.</li>
	<li>Wash three times with PBS for 5 min each.</li>
	<li>Mount with fluorescence mounting media containing DAPI. Store at 4 &#176;C in the dark before analysis. 
	CAUTION: Wear eye protection and compatible chemical-resistant gloves.</li>
	<li>Photograph the slides.
	<ol>
		<li>Use a microscope equipped with fluorescence epi-illumination and filter sets for DAPI and tetramethylrhodamine (refer to the Table of Materials). Set the aperture to the maximum and the brightness to auto-exposure.</li>
		<li>Acquire separate images at 400x magnification for the blue and the red channels. Open the images in ImageJ. Adjust the brightness and contrast if necessary (Image &#62; Adjust &#62; Brightness/contrast).</li>
		<li>Set each image to 8-bit (Image &#62; Type &#62; 8-bit). Overlay the DAPI and WGA images. Use the blue channel for DAPI and the red channel for WGA; set the green and gray channels to none (Image &#62; Color &#62; Merge channels)31.</li>
	</ol>
	</li>
	<li>Determine the cardiomyocyte diameters at the level of the nucleus in transverse sections of the interventricular septum.
	<ol>
		<li>Define the scale of the images in ImageJ. For this purpose, photograph an object of known size (e.g., a hemocytometer chamber at the same magnification as the heart sections; step 4.4).</li>
		<li>Use the straight-line tool to draw a line from beginning to end of the known structure (Analyze &#62; Set scale). 
		NOTE: The distance in pixels will be displayed automatically; the known distance and unit of length will have to be entered. Proceed with cardiomyocyte measurements at the level of the nucleus.</li>
		<li>Draw a straight line from the WGA-positive membrane through the DAPI-positive nucleus to the opposite site of the WGA-positive cell membrane (Analyze &#62; Measure). In the results window, make sure that the length values have a meaningful number of decimal places (Analyze &#62; Set measurements &#62; Decimal places).</li>
		<li>Measure at least 100 cells per section and three sections per heart. Export the results to Excel (Click on Results &#62; File &#62; Save as &#62; .csv)6,31.</li>
	</ol>
	</li>
</ol>
5. Pecam-1 Immunostaining
<ol>
	<li>Perform antigen unmasking.
	<ol>
		<li>Add 1,600 mL of sodium citrate buffer (10 mM sodium citrate, 0.05% Tween 20, pH 6.0) to a pressure cooker. Place the pressure cooker on the hotplate and turn it on full power. Do not secure the lid of the pressure cooker at this point; simply rest it on top. 
		CAUTION: Hot!</li>
		<li>Once the sodium citrate buffer is boiling, transfer the slides from step 2.5 to the pressure cooker. Secure the pressure cooker lid. As soon as the cooker has reached full pressure, wait for 7 min. When 7 min have elapsed, turn off the hotplate and place the pressure cooker in an empty sink. Activate the pressure release valve and run cold water over the cooker. Once it has de-pressurized, open the lid and run cold water into the cooker for 5 min. Place the slides in 200 mL of PBS. 
		NOTE: Alternatively, microwave antigen unmasking could be used, although the risk of overheating is increased.</li>
	</ol>
	</li>
	<li>Use 0.3% hydrogen peroxide in methanol to block endogenous peroxidase activity for 5 min. Rinse the slides for three times for 2 min each in 200 mL of PBS. 
	CAUTION: Flammable and toxic!</li>
	<li>Incubate the slides for 15 min in diluted normal blocking serum (5% normal goat serum in PBS) that also contains an avidin block (4 drops in 1 mL).</li>
	<li>Carefully tap the liquid from the sections and incubate them with Pecam-1 antibody from rabbit, diluted 1:50 in PBS containing 2.5% normal goat serum and 4 drops of biotin block per mL. Incubate the slides overnight in a humid chamber at 4 &#176;C.</li>
	<li>Wash the slides three times for 5 min each in 200 mL of PBS. Incubate the sections with biotinylated goat anti-rabbit IgG antibody diluted 1:200 in PBS containing 2.5% normal goat serum for 1 h at room temperature. Wash the slides three times for 5 min each in 200 mL of PBS.</li>
	<li>Incubate the sections with an avidin/biotin-based peroxidase system for 20 min (reagent A and reagent B need to be combined 30 mins prior to use). Wash the slides three times for 5 min each in 200 mL of PBS.</li>
	<li>Dissolve 1 3,3&#39;-diaminobenzidine (DAB) and 1 urea hydrogen peroxide tablet in 5 mL of double-distilled water. Incubate the sections with DAB solution for approximately 3 min, carefully monitoring color development. Stop the color reaction by gently washing the slides in 200 mL of PBS. 
	CAUTION: Carcinogenic; wear chemical-resistant gloves!</li>
	<li>Counterstain the nuclei for 6 min with hematoxylin. Rinse in running tap water for 2 min. Dehydrate three times for 2 min each in 200 mL of 100% alcohol. Clear three times for 2 min each in 200 mL of xylene or a xylene substitute. Mount in a xylene-based mounting medium.</li>
	<li>Photograph the slides (at least ten fields at 40x magnification from the interventricular septum of each heart) and measure the Pecam-1 area density using the freely available ImageJ software31. Use the color deconvolution32 plugin for DAB and hematoxylin and adjust the image contrast to the same level. 
	NOTE: In case the brown and purple/blue color have significant spectral overlap, which might cause difficulties with color deconvolution, one could try different brands of hematoxylin solution to obtain clear, light-blue nuclear staining. Alternatively, immunofluorescence or manual counting of the capillaries could be performed.</li>
</ol>

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A., 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=Recommendations+for+quantification+of+Doppler+echocardiography:+a+report+from+the+Doppler+Quantification+Task+Force+of+the+Nomenclature+and+Standards+Committee+of+the+American+Society+of+Echocardiography.">Recommendations for quantification of Doppler echocardiography: a report from the Doppler Quantification Task Force of the Nomenclature and Standards Committee of the American Society of Echocardiography.</a> J Am Soc Echocardiogr. 15 (2), 167-184 (2002).</li><li>van Laake, L. W., 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=Monitoring+of+cell+therapy+and+assessment+of+cardiac+function+using+magnetic+resonance+imaging+in+a+mouse+model+of+myocardial+infarction.">Monitoring of cell therapy and assessment of cardiac function using magnetic resonance imaging in a mouse model of myocardial infarction.</a> Nat Protoc. 2 (10), 2551-2567 (2007).</li><li>Wagner, K. D., 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=The+Wilms'+tumor+suppressor+Wt1+is+expressed+in+the+coronary+vasculature+after+myocardial+infarction.">The Wilms' tumor suppressor Wt1 is expressed in the coronary vasculature after myocardial infarction.</a> FASEB J. 16 (9), 1117-1119 (2002).</li><li>Wagner, K. D., 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=RNA+induction+and+inheritance+of+epigenetic+cardiac+hypertrophy+in+the+mouse.">RNA induction and inheritance of epigenetic cardiac hypertrophy in the mouse.</a> Dev Cell. 14 (6), 962-969 (2008).</li><li>Schneider, C. A., Rasband, W. S., Eliceiri, K. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=NIH+Image+to+ImageJ:+25+years+of+image+analysis.">NIH Image to ImageJ: 25 years of image analysis.</a> Nat Methods. 9 (7), 671-675 (2012).</li><li>Ruifrok, A. C., Johnston, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantification+of+histochemical+staining+by+color+deconvolution.">Quantification of histochemical staining by color deconvolution.</a> Anal Quant Cytol Histol. 23 (4), 291-299 (2001).</li><li>Lazzeroni, D., Rimoldi, O., Camici, P. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=From+Left+Ventricular+Hypertrophy+to+Dysfunction+and+Failure.">From Left Ventricular Hypertrophy to Dysfunction and Failure.</a> Circ J. 80 (3), 555-564 (2016).</li><li>Ismail, J. A., 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=Immunohistologic+labeling+of+murine+endothelium.">Immunohistologic labeling of murine endothelium.</a> Cardiovasc Pathol. 12 (2), 82-90 (2003).</li><li>Benton, R. L., Maddie, M. A., Minnillo, D. R., Hagg, T., Whittemore, S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Griffonia+simplicifolia+isolectin+B4+identifies+a+specific+subpopulation+of+angiogenic+blood+vessels+following+contusive+spinal+cord+injury+in+the+adult+mouse.">Griffonia simplicifolia isolectin B4 identifies a specific subpopulation of angiogenic blood vessels following contusive spinal cord injury in the adult mouse.</a> J Comp Neurol. 507 (1), 1031-1052 (2008).</li><li>Ayoub, A. E., Salm, A. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Increased+morphological+diversity+of+microglia+in+the+activated+hypothalamic+supraoptic+nucleus.">Increased morphological diversity of microglia in the activated hypothalamic supraoptic nucleus.</a> J Neurosci. 23 (21), 7759-7766 (2003).</li><li>Maddox, D. E., Shibata, S., Goldstein, I. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stimulated+macrophages+express+a+new+glycoprotein+receptor+reactive+with+Griffonia+simplicifolia+I-B4+isolectin.">Stimulated macrophages express a new glycoprotein receptor reactive with Griffonia simplicifolia I-B4 isolectin.</a> Proc Natl Acad Sci U S A. 79 (1), 166-170 (1982).</li><li>dela Paz, N. G., D'Amore, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Arterial+versus+venous+endothelial+cells.">Arterial versus venous endothelial cells.</a> Cell Tissue Res. 335 (1), 5-16 (2009).</li></ol>

The authors have nothing to disclose.

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 ...

echocardiographic-histological-examination-cardiac-morphology

Research

JoVE Journal

Medicine

21.2K Views.  CNRS, INSERM, iBV. 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.

Video: Echocardiographic and Histological Examination of Cardiac Morphology in the Mouse

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 ...

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.

Diastolic dysfunction is a prominent feature of right ventricular (RV) remodeling associated with conditions of pressure overload. However, the RV ...

Transthoracic Echocardiographic Examination in the Rabbit Model

Large animal models such as the rabbit are valuable for translational preclinical research. Rabbits have a similar cardiac electrophysiology compared to that of humans and that of other large animal models such as dogs and pigs. However, the rabbit model has the additional advantage of lower maintenance costs compared to other large animal models. The longitudinal evaluation of cardiac function using echocardiography, when appropriately implemented, is a useful methodology for preclinical assessment of novel therapies for heart failure with reduced ejection fraction (e.g. cardiac regeneration). The correct use of this non-invasive tool requires the implementation of a standardized examination protocol following international guidelines. Here we describe, step by step, a detailed protocol supervised by veterinary cardiologists for performing echocardiography in the rabbit model, and demonstrate how to correctly obtain the different echocardiographic views and imaging planes, as well as the different imaging modes available in a clinical echocardiography system routinely used in human and veterinary patients.

Here we describe, step by step, a detailed protocol for performing echocardiography in the rabbit model. We show how to correctly obtain the different echocardiographic views and imaging planes, as well as the different imaging modes available in a clinical echocardiography system routinely used in human and veterinary patients.

Large animal models such as the rabbit are valuable for translational preclinical research. Rabbits have a similar cardiac electrophysiology compared to ...