Name: imaging and analysis of oil red o-stained whole aorta lesions in an aneurysm hyperlipidemia mouse model
Uploaded: 2022-05-02T14:00:00
Description: Watch this Scientific Journal Video about Imaging and Analysis of Oil Red O-Stained Whole Aorta Lesions in an Aneurysm Hyperlipidemia Mouse Model at JoVE.com

This work was supported, in part, by a Joint Biology Consortium Microgrant provided under NIH grant P30AR070253 (P.-Y.C.), and HL135582 (M.S.). We are grateful to R. Webber and L. Coon for maintaining the mice used in this study.

mT/mG (stock no. 007676), and Apoe-/- (stock no. 002052) mice were purchased from the Jackson Laboratory. Myh11-CreERT2 mice were a gift from Stefan Offermanns (available from the Jackson Laboratory as stock no. 019079). Tgfbr2fl/fl mice were obtained from Harold L. Moses (Vanderbilt University). All animal procedures were performed using protocols approved by the Yale University Institutional Animal Care and Use Committee.
1. Mice
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	<li>Produce ...

<ol>
	<li>Lusis, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Atherosclerosis.">Atherosclerosis.</a> Nature. 407, 233-241 (2000).</li><li>Emini Veseli, B., 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=Animal+models+of+atherosclerosis.">Animal models of atherosclerosis.</a> European Journal of Pharmacology. 816, 3-13 (2017).</li><li>Plump, A. S., 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=Severe+hypercholesterolemia+and+atherosclerosis+in+apolipoprotein+E-deficient+mice+created+by+homologous+recombination+in+ES+cells.">Severe hypercholesterolemia and atherosclerosis in apolipoprotein E-deficient mice created by homologous recombination in ES cells.</a> Cell. 71, 343-353 (1992).</li><li>Zhang, S. H., Reddick, R. L., Piedrahita, J. A., Maeda, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spontaneous+hypercholesterolemia+and+arterial+lesions+in+mice+lacking+apolipoprotein+E.">Spontaneous hypercholesterolemia and arterial lesions in mice lacking apolipoprotein E.</a> Science. 258, 468-471 (1992).</li><li>Ishibashi, S., 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=Hypercholesterolemia+in+low+density+lipoprotein+receptor+knockout+mice+and+its+reversal+by+adenovirus-mediated+gene+delivery.">Hypercholesterolemia in low density lipoprotein receptor knockout mice and its reversal by adenovirus-mediated gene delivery.</a> Journal of Clinical Investigation. 92, 883-893 (1993).</li><li>Nakashima, Y., Plump, A. S., Raines, E. W., Breslow, J. L., Ross, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ApoE-deficient+mice+develop+lesions+of+all+phases+of+atherosclerosis+throughout+the+arterial+tree.">ApoE-deficient mice develop lesions of all phases of atherosclerosis throughout the arterial tree.</a> Arteriosclerosis Thrombosis. 14, 133-140 (1994).</li><li>Chen, P. Y., 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=Smooth+muscle+cell+reprogramming+in+aortic+aneurysms.">Smooth muscle cell reprogramming in aortic aneurysms.</a> Cell Stem Cell. 26, 542-557 (2020).</li><li>Andres-Manzano, M. J., Andres, V., Dorado, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oil+Red+O+and+Hematoxylin+and+Eosin+Staining+for+Quantification+of+Atherosclerosis+Burden+in+Mouse+Aorta+and+Aortic+Root.">Oil Red O and Hematoxylin and Eosin Staining for Quantification of Atherosclerosis Burden in Mouse Aorta and Aortic Root.</a> Methods in Molecular Biology. 1339, 85-99 (2015).</li><li>Chen, P. Y., 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=Endothelial+TGF-beta+signalling+drives+vascular+inflammation+and+atherosclerosis.">Endothelial TGF-beta signalling drives vascular inflammation and atherosclerosis.</a> Nature Metabolism. 1, 912-926 (2019).</li><li>Mehlem, A., Hagberg, C. E., Muhl, L., Eriksson, U., Falkevall, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imaging+of+neutral+lipids+by+oil+red+O+for+analyzing+the+metabolic+status+in+health+and+disease.">Imaging of neutral lipids by oil red O for analyzing the metabolic status in health and disease.</a> Nature Protocols. 8, 1149-1154 (2013).</li><li>Ferruzzi, J., Madziva, D., Caulk, A. W., Tellides, G., Humphrey, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Compromised+mechanical+homeostasis+in+arterial+aging+and+associated+cardiovascular+consequences.">Compromised mechanical homeostasis in arterial aging and associated cardiovascular consequences.</a> Biomechanics and Modeling Mechanobiology. 17, 1281-1295 (2018).</li></ol>

Apolipoprotein E (Apoe) and low density lipoprotein receptor (Ldlr) deficient mice are useful for studying development and treatment of atherosclerosis. Investigators can evaluate the impact of genetics and therapeutic manipulations on atherosclerosis-related diseases initiation, progression, and regression using Oil Red O staining of the whole aorta9. Aorta Oil Red O staining and lesion quantification is the gold standard endpoint for atherosclerosis research. This technique is ...

Coronary artery disease, a leading cause of mortality in the US, is usually caused by atherosclerosis, a process that leads to the buildup of plaque inside arterial walls1. Hyperlipidemia-prone Apoe- and Ldlr-deficient mice are central to investigations of atherosclerosis and its complications and development of therapies2,3,4,5. Quantification of atherosclerotic lesions from an en face aorta is an important endpoint analysis for evaluating the impact of genetic manipulation in different cell types. It also helps to study novel therapies designed to affect atherosclerotic disease initiation, progression, and regression. Atherosclerotic lesions can form anywhere in the aorta and its branches (i.e., brachiocephalic, carotid and subclavian arteries in the chest, as well as renal, common iliac and femoral arteries below the diaphragm)6. A comprehensive evaluation of atherosclerosis burden and appropriate therapy requires assessment of disease burden in different locations, a challenge that is often overlooked.
This protocol describes how to perform a comprehensive analysis of atherosclerotic lesions, starting with an unopened whole aorta and proceeding to en face preparation, in a single mouse. Unopened whole aorta Oil Red O staining allows rapid, qualitative assessment of lipid-laden plaques in the entire aorta and its branches, while en face preparation provides a quantitative assessment of atherosclerotic lesion distribution in the mouse aorta.
The technique uses 8 week-old mice with a smooth muscle cell-specific TGF&#946;R2 deletion on the Apoe-/- hyperlipidemic background (MYH11-CreERT2;Tgfbr2f/f;mT/mGf/f;Apoe-/-; hereafter referred to as TGF&#946;R2iSMC-Apoe mice) and littermate Apoe-/- controls (MYH11-CreERT2;mT/mGf/f;Apoe-/-; hereafter referred to as Apoe-/- mice). The animals are kept for 16 weeks on a high cholesterol&#160;high fat diet (HCHFD) as study materials7. At study termination, the unopened whole aortas are stained and imaged (including all major branches) with Oil Red O for qualitative assessment of lipid-laden plaques. The aortas are cut open via en face preparation, and all atherosclerotic lesions are imaged and quantified. This protocol can be used to study atherosclerotic lesion development in Apoe-/- or Ldlr-/- hyperlipidemia mice models and extended to general aorta-related vascular biology applications.

<table>
	<tbody>
		<tr>
			<td>1.5 mL Eppendorf tube</td>
			<td>DENVILLE</td>
			<td>C2170</td>
			<td></td>
		</tr>
		<tr>
			<td>10 mL syringe</td>
			<td>BD</td>
			<td>302995</td>
			<td></td>
		</tr>
		<tr>
			<td>16% Formaldehyde</td>
			<td>Polysciences</td>
			<td>18814-10</td>
			<td></td>
		</tr>
		<tr>
			<td>70% ethanol</td>
			<td>VWR</td>
			<td>RC2546.70-5</td>
			<td>To clean the dissection tools</td>
		</tr>
		<tr>
			<td>Black dissection wax</td>
			<td>CR Scientific</td>
			<td>C3541</td>
			<td></td>
		</tr>
		<tr>
			<td>Corn oil</td>
			<td>Sigma</td>
			<td>C8267</td>
			<td>Solvent for Tamoxifen</td>
		</tr>
		<tr>
			<td>DNeasy Blood &#38; Tissue kit</td>
			<td>QIAGEN</td>
			<td>69506</td>
			<td>To isolate DNA from mouse ear</td>
		</tr>
		<tr>
			<td>Dulbecco&#8217;s Phosphate-buffered saline (1X DPBS), pH 7.4</td>
			<td>Gibco</td>
			<td>14190-144</td>
			<td></td>
		</tr>
		<tr>
			<td>Fine scissors</td>
			<td>Fine Science Tools</td>
			<td>14059-11</td>
			<td>To cut the mouse skin and open the ribcage</td>
		</tr>
		<tr>
			<td>Fisherbrand Economy Plain Glass Microscope Slides</td>
			<td>Fisher Scientific</td>
			<td>12-550-A3</td>
			<td></td>
		</tr>
		<tr>
			<td>High cholesterol high fat diet</td>
			<td>Research Diets</td>
			<td>D12108</td>
			<td>To induce atherosclerosis</td>
		</tr>
		<tr>
			<td>Imaging software</td>
			<td>National Institutes of Health</td>
			<td>Image J</td>
			<td>Aortic lesion quantification</td>
		</tr>
		<tr>
			<td>Isopropanol</td>
			<td>VWR</td>
			<td>JT9079-5</td>
			<td></td>
		</tr>
		<tr>
			<td>Kimwipes</td>
			<td>Fisher Scientific</td>
			<td>06-666A</td>
			<td>To clean the glass microscope slides</td>
		</tr>
		<tr>
			<td>McPherson-Vannas Micro Dissecting Spring Scissors</td>
			<td>ROBOZ</td>
			<td>RS-5602</td>
			<td>To separate the heart and the aorta and to cut open the aorta and aorta branches</td>
		</tr>
		<tr>
			<td>Microscope control software</td>
			<td>Olympus</td>
			<td>DP Controller</td>
			<td>For aorta imaging</td>
		</tr>
		<tr>
			<td>Minutien pins</td>
			<td>Fine Science Tools</td>
			<td>26002-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Needle-25G</td>
			<td>BD</td>
			<td>305124</td>
			<td></td>
		</tr>
		<tr>
			<td>NonWoven Sponge</td>
			<td>McKesson</td>
			<td>94442000</td>
			<td></td>
		</tr>
		<tr>
			<td>Oil Red O</td>
			<td>Sigma</td>
			<td>O-0625</td>
			<td>To stain the atherosclerosis lesions</td>
		</tr>
		<tr>
			<td>Pall Acrodisc Sterile Syringe Filters with Super Membrane</td>
			<td>VWR</td>
			<td>28143-312</td>
			<td>To filter working Oil Red O solution</td>
		</tr>
		<tr>
			<td>Spring Scissors</td>
			<td>Fine Science Tools</td>
			<td>15021-15</td>
			<td>To dissect and clean the aorta</td>
		</tr>
		<tr>
			<td>Statistical software</td>
			<td>GraphPad</td>
			<td>Prism 8</td>
			<td>Statical analysis</td>
		</tr>
		<tr>
			<td>Stereomicroscope</td>
			<td>Nikon</td>
			<td>SMZ1000</td>
			<td>For aorta dissection</td>
		</tr>
		<tr>
			<td>Stereomicroscope</td>
			<td>Olympus</td>
			<td>SZX16</td>
			<td>For aorta imaging</td>
		</tr>
		<tr>
			<td>Tamoxifen</td>
			<td>Sigma</td>
			<td>T5648</td>
			<td>To induce Cre-loxP recombination</td>
		</tr>
		<tr>
			<td>Tissue-Tek O.C.T Compound, Sakura Finetek</td>
			<td>VWR</td>
			<td>25608-930</td>
			<td></td>
		</tr>
		<tr>
			<td>Tweezer Style 4</td>
			<td>Electron Microscopy Sciences</td>
			<td>0302-4-PO</td>
			<td>To cut the mouse skin and open the ribcage</td>
		</tr>
		<tr>
			<td>Tweezer Style 5</td>
			<td>Electron Microscopy Sciences</td>
			<td>0302-5-PO</td>
			<td>To dissect and clean the aorta</td>
		</tr>
	</tbody>
</table>

imaging and analysis of oil red o-stained whole aorta lesions in an aneurysm hyperlipidemia mouse model

Apolipoprotein E (Apoe)- or low density lipoprotein receptor (Ldlr)-deficient hyperlipidemic mice are the two most commonly used models for atherosclerosis research. They are used to study the impact of a various genetic factors and different cell types on atherosclerotic lesion formation and as well as test the development of new therapies. Isolation, excision of the whole aorta, and quantification of Oil Red O-stained atherosclerotic lesions are basic morphometric methods used to evaluate atherosclerotic burden. The goal of this protocol is to describe an optimized, step-by-step surgical method to dissect, perfuse-fix, isolate, stain, image and analyze atherosclerotic lesions in mouse aortas with Oil Red O. Because atherosclerotic lesions can form anywhere in the entire aortic tree, this whole aorta Oil Red O staining method has the advantage of evaluating lipid-laden plaques in the entire aorta and all branches in a single mouse. In addition to Oil Red O staining, fresh isolated whole aortas can be used for variety of in vitro and in vivo experiments and cell isolations.

In this protocol, atherosclerotic lesions in TGF&#946;R2iSMC-Apoe mice were analyzed after 4 months on a HCHF diet7. In addition to extensive atherosclerosis, these mice developed both thoracic and abdominal aortic aneurysms, as previously reported. Compared to Apoe-/- mice, TGF&#946;R2iSMC-Apoe mice aortic walls showed severe atherosclerosis, making it difficult to dissect the lesions (Figure 2C,D,E). In addition, the...

Watch this Scientific Journal Video about Imaging and Analysis of Oil Red O-Stained Whole Aorta Lesions in an Aneurysm Hyperlipidemia Mouse Model at JoVE.com

Imaging and Analysis of Oil Red O-Stained Whole Aorta Lesions in an Aneurysm Hyperlipidemia Mouse Model

This protocol provides a step-by-step procedure to analyze atherosclerotic burden in mice. Investigators can use this protocol to compare the abundance, location, and size of atherosclerotic lesions in different animals.

Apolipoprotein E (Apoe)- or low density lipoprotein receptor (Ldlr)-deficient hyperlipidemic mice are the two most commonly used models for ...

The quantification of atherosclerotic lesions in apoE and other types of hyperlipidemic mice is key to assessment of various genetic factors and new therapies. Our protocol provides step-by-step instructions for analysis of atherosclerotic burden in qualitative and quantitative manner in a single mouse. 16 weeks after inducing atherosclerosis, before perfusing the heart, load a 10 milliliter syringe with 10 milliliters of DPBS and attach a 25 gauge needle.Lift the abdominal skin of the experimental mouse with tweezers and use fine scissors to cut the skin from the base of the abdomen to the top of the neck. Open the abdominal wall below the ribcage and use the tweezers to lift the sternum to access the diaphragm. Cut the diaphragm and cut away the ribcage to expose the thoracic cavity.Next, make a small incision in the right atrium of the heart and slowly inject the entire volume of DPBS into the apical left ventricular puncture. The liver and kidney will turn light brown in color. When all of the saline has been perfused, use a nonwoven sponge to clean the chest cavity of any extraneous blood and fluid.After the chest cavity has been wiped, remove the non-experimental organs and cut the clavicle with tweezers and fine scissors. Place the mouse under a stereo microscope and use the tweezers and spring scissors to dissect the aorta. When the aorta has been isolated, cover the tissue with a saline-soaked nonwoven sponge and dissect the aortic branches including the brachiocephalic, carotid, subclavian, renal, common iliac, and femoral arteries.When all of the arteries branching from the aorta have been isolated, use tweezers and spring scissors to carefully dissect and remove the adventitial adipose and connective tissue around the aorta and aorta branches. A successful isolation of aorta and aortic branches requires practice and patience. To fix the vascular tree, first load a 10 milliliter syringe with 4%formaldehyde in 1X DPBS and attach a 25 gauge needle.Remember to always prepare 4%formaldehyde inside a fume hood. Insert the needle into the apical left ventricular puncture and slowly inject the entire volume of fixative. Clean the chest cavity of any extraneous fluids with a nonwoven sponge as demonstrated and use tweezers and micro dissecting spring scissors to separate the heart from the aorta.When the tissues have been separated, isolate and excise the aorta and its major vessel from one millimeter above the carotid artery to the end of the femoral artery and place the vessel in a container of DPBS. For Oil Red O staining of the unopened whole aorta, use Minutien pins to secure the vessel onto a wax Petri dish and rinse the vessel with fresh DPBS. Pour 25 milliliters of fresh 0.45 micrometer pore-filtered Oil Red O solution into the dish for a 60-minute stain at room temperature.Submerge the tissue with 60%isopropanol for a 20-minute wash at room temperature. At the end of the incubation, rinse the vessel three times with fresh distilled water for five minutes per wash and place the dish under the dissecting microscope. Use tweezers and spring scissors to gently clean all of the perivascular adipose tissue around the aorta to avoid any false background Oil Red O staining and transfer the vessel to a clean glass microscope slide.Oil Red O will label the lipid-rich plaque red, leaving the non-plaque containing areas pale in color. Then acquire digital high-resolution micrographs with a light microscope equipped with a camera and save the images preferably in tagged image file format. For en face mounting of the aortic tissue sample, transfer the vessel to a wax Petri dish and cover the tissue with fresh DPBS.Sever the carotid and subclavian arteries of the aortic arch and the iliac arteries in the abdominal aorta one to two millimeters after the bifurcations. Sever the renal arteries. Next, use micro dissecting spring scissors to longitudinally open the aorta preparation along the inner curvature and iliac arteries and cut the three branches of the aortic arch along the greater curvature until the base level of the inner curvature.Then use Minutien pins to secure the aorta flat against the dish without stretching with the lumen side facing up and cover the tissue with fresh DPBS. Compared to apolipoprotein E knockout mice, the aortic walls of smooth muscle cell TGF-beta-R2 knockout apolipoprotein E mice demonstrate severe atherosclerosis, making it difficult to dissect the lesions. In addition, the aneurysms are particularly extensive below the suprarenal aorta, highly reminiscent of advanced human aortic aneurysms.Here, a representative image of an unopened aorta from a high-cholesterol high-fat diet-fed TGF-beta-R2 knockout apolipoprotein E mouse stained with Oil Red O is shown. The mouse developed both an ascending and an abdominal aortic aneurysm with accelerated atherosclerotic lesion formation observed in the brachiocephalic, carotid, subclavian, iliac, femoral, and renal arteries. This en face Oil Red O staining of TGF-beta-R2 knockout apolipoprotein E mouse tissue reveals severe aneurysmal enlargement and marked elongation of the entire aorta compared to the apolipoprotein E knockout mouse group.It is important to be able to distinguish Oil Red O stained plaques from false background Oil Red O stained perivascular adipose tissues. Atherosclerosis plaques are three-dimensional phenomena. After en face aortic 2D lesion quantification, we recommend plaque set analysis such as aortic roots and the brachiocephalic artery.This protocol can also be used to decide whether a particular genetic factor, intervention, or treatment affects atherosclerosis progression or regression in these models.

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