Name: using en face immunofluorescence staining to observe vascular endothelial cells directly
Uploaded: 2019-08-20T12:30:00
Description: Watch this Scientific Journal Video about Using En Face Immunofluorescence Staining to Observe Vascular Endothelial Cells Directly at JoVE.com

This study was supported by the National Natural Science Foundation of China (Grant No. 81670451, 81770430), the Shanghai Rising-Star Program (Grant No. 17QA1403000), and the Science Technology Committee of the Shanghai Municipal Government (Grant No. 14441903002, 15411963700).

All animal experiments were conducted in accordance with experimental protocols approved by the Committee on Animal Resources of Shanghai Jiao Tong University.
1. Perfusion of the mouse aorta
<ol>
	<li>Briefly, anesthetize 12-week-old C57BL/6 mice with intraperitoneal injections of sodium pentobarbital (50 mg/kg body weight). Confirm proper anesthetization by gently pinching the tail. 
	NOTE: If no movement is observed, the animal is sufficiently anesthetized to start the experiments.</...

<ol>
	<li>Gimbrone, M. A., Garcia-Cardena, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endothelial+Cell+Dysfunction+and+the+Pathobiology+of+Atherosclerosis.">Endothelial Cell Dysfunction and the Pathobiology of Atherosclerosis.</a> Circulation Research. 118 (4), 620-636 (2016).</li><li>Zhou, J., Li, Y. S., Chien, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shear+stress-initiated+signaling+and+its+regulation+of+endothelial+function.">Shear stress-initiated signaling and its regulation of endothelial function.</a> Arteriosclerosis, Thrombosis, and Vascular Biology. 34 (10), 2191-2198 (2014).</li><li>Tarbell, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shear+stress+and+the+endothelial+transport+barrier.">Shear stress and the endothelial transport barrier.</a> Cardiovascular Research. 87 (2), 320-330 (2010).</li><li>Warren, B. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+method+for+the+production+of+&amp;#34;en+face&amp;#34;+preparations+one+cell+in+thickness.">A method for the production of &amp;#34;en face&amp;#34; preparations one cell in thickness.</a> Journal of Microscopy. 85 (4), 407-413 (1965).</li><li>Azuma, K., 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=A+new+En+face+method+is+useful+to+quantitate+endothelial+damage+in+vivo.">A new En face method is useful to quantitate endothelial damage in vivo.</a> Biochemical and Biophysical Research Communications. 309 (2), 384-390 (2003).</li><li>Son, D. J., 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+atypical+mechanosensitive+microRNA-712+derived+from+pre-ribosomal+RNA+induces+endothelial+inflammation+and+atherosclerosis.">The atypical mechanosensitive microRNA-712 derived from pre-ribosomal RNA induces endothelial inflammation and atherosclerosis.</a> Nature Communications. 4, 3000 (2013).</li><li>Go, Y. M., 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=Disturbed+flow+enhances+inflammatory+signaling+and+atherogenesis+by+increasing+thioredoxin-1+level+in+endothelial+cell+nuclei.">Disturbed flow enhances inflammatory signaling and atherogenesis by increasing thioredoxin-1 level in endothelial cell nuclei.</a> PLOS ONE. 9 (9), e108346 (2014).</li><li>Kundumani-Sridharan, V., Dyukova, E., Hansen, D. E., Rao, G. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=12/15-Lipoxygenase+mediates+high-fat+diet-induced+endothelial+tight+junction+disruption+and+monocyte+transmigration:+a+new+role+for+15(S)-hydroxyeicosatetraenoic+acid+in+endothelial+cell+dysfunction.">12/15-Lipoxygenase mediates high-fat diet-induced endothelial tight junction disruption and monocyte transmigration: a new role for 15(S)-hydroxyeicosatetraenoic acid in endothelial cell dysfunction.</a> The Journal of Biological Chemistry. 288 (22), 15830-15842 (2013).</li><li>Liu, Z. H., 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=C1q/TNF-related+protein+1+promotes+endothelial+barrier+dysfunction+under+disturbed+flow.">C1q/TNF-related protein 1 promotes endothelial barrier dysfunction under disturbed flow.</a> Biochemical and Biophysical Research Communications. 490 (2), 580-586 (2017).</li><li>Wang, X. Q., 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=Thioredoxin+interacting+protein+promotes+endothelial+cell+inflammation+in+response+to+disturbed+flow+by+increasing+leukocyte+adhesion+and+repressing+Kruppel-like+factor+2.">Thioredoxin interacting protein promotes endothelial cell inflammation in response to disturbed flow by increasing leukocyte adhesion and repressing Kruppel-like factor 2.</a> Circulation Research. 110 (4), 560-568 (2012).</li><li>Mitra, S., Deshmukh, A., Sachdeva, R., Lu, J., Mehta, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oxidized+low-density+lipoprotein+and+atherosclerosis+implications+in+antioxidant+therapy.">Oxidized low-density lipoprotein and atherosclerosis implications in antioxidant therapy.</a> The American Journal of the Medical Sciences. 342 (2), 135-142 (2011).</li><li>Stancel, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interplay+between+CRP,+Atherogenic+LDL,+and+LOX-1+and+Its+Potential+Role+in+the+Pathogenesis+of+Atherosclerosis.">Interplay between CRP, Atherogenic LDL, and LOX-1 and Its Potential Role in the Pathogenesis of Atherosclerosis.</a> Clinical Chemistry. 62 (2), 320-327 (2016).</li><li>Nerem, R. M., Levesque, M. J., Cornhill, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vascular+Endothelial+Morphology+as+an+Indicator+of+the+Pattern+of+Blood+Flow.">Vascular Endothelial Morphology as an Indicator of the Pattern of Blood Flow.</a> Journal of Biomechanical Engineering. 103 (3), 172-176 (1981).</li></ol>

The endothelium is exposed to numerous proatherogenic factors, including lipids, inflammatory mediators, and fluid shear stress1,11,12. Direct observation of endothelial cells in situ provides the special advantages to analyze changes in cell morphology, intercellular junctions, and molecule expression patterns in response to the injury stimuli.
Previous studies have provided two different en face imm...

The early changes in the vasculature primarily initiate in the endothelium, which functions as a selective barrier between the blood and the vessel wall with its intercellular tight junctional complexes1. Substantial evidence points to a critical role for the mechanical effects of blood flow in modulating endothelial function2. Fluid shear stress, a frictional force generated by blood flow, differentially shapes endothelial cell morphology and function, depending on the specific flow paradigms at different vascular sites2,3. Atherosclerotic lesions preferentially occur at sites of disturbed blood flow (d-flow), such as vessel curvatures, flow dividers, and branch points, as compared to regions of steady flow (s-flow), such as the straight segment of the artery. Therefore, direct observation of endothelial morphology and molecule expression patterns should provide important insights into the structural and functional phenotypes of endothelial cells under varying flow paradigms.
Cultured endothelial cells may not express the actual phenotype as they do in vivo partly due to the loss of impact of fluid shear stress, surrounding cytokines, and cell-cell or cell-extracellular matrix interactions. To aid this, the intact endothelial cell monolayer can be studied on transverse sections using classical immunohistochemistry. However, the endothelial monolayer is so thin and fragile that it usually cannot be observed clearly. En face immunohistochemistry has been used to observe the inner surface of the endothelium but is either complicated or erratic in its results because the endothelium is easily stripped from the underlying tissue, or just part of the arterial wall of rats or rabbits, whose walls are thick, is mounted4,5.
Mouse models have considerable advantages over other animals in many respects. Here, we employ a modified en face immunofluorescence technique to analyze endothelial cells of the aortic arch and thoracic aorta in C57BL/6 mouse. Such a technique has been widely used to study the endothelial pathophysiology in different flow patterns and in the development of atherosclerosis6,7,8,9,10. This method allows scientists to observe the entire surface of the endothelium clearly and to compare the expression patterns of a given protein in regions under different fluid shear stress.

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	<tbody>
		<tr height="40">
			<td height="40" style="height:40px;width:223px;">Antifade mountant</td>
			<td style="width:126px;">Servicebio</td>
			<td style="width:134px;">G1401</td>
			<td style="width:174px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:223px;">Delicate Forceps</td>
			<td style="width:126px;">RWD Life Science</td>
			<td style="width:134px;">F11001-11</td>
			<td style="width:174px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:223px;">Delicate Scissors</td>
			<td style="width:126px;">RWD Life Science</td>
			<td style="width:134px;">S12003-09</td>
			<td style="width:174px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:223px;">Dissecting Forceps</td>
			<td style="width:126px;">RWD Life Science</td>
			<td style="width:134px;">F12005-10</td>
			<td style="width:174px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:223px;">Mciro Spring Scissors</td>
			<td style="width:126px;">RWD Life Science</td>
			<td style="width:134px;">S11001-08</td>
			<td style="width:174px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:223px;">Polyoxyethylene octyl phenyl ether (Triton X-100)</td>
			<td style="width:126px;">Amresco</td>
			<td style="width:134px;">M143</td>
			<td style="width:174px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:223px;">Polysorbate 20 (Tween 20)</td>
			<td style="width:126px;">Amresco</td>
			<td style="width:134px;">0777</td>
			<td style="width:174px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:223px;">VCAM-1 antibody</td>
			<td style="width:126px;">Abcam</td>
			<td style="width:134px;">ab134047</td>
			<td style="width:174px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:223px;">VE-Cadherin antibody</td>
			<td style="width:126px;">BD Biosciences</td>
			<td style="width:134px;">555289</td>
			<td style="width:174px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:223px;">Alexa Fluor 555 labeled anti-rabbit IgG</td>
			<td style="width:126px;">invitrogen</td>
			<td style="width:134px;">A-31572</td>
			<td style="width:174px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:223px;">Alexa Fluor 488 labeled anti-rat IgG</td>
			<td style="width:126px;">invitrogen</td>
			<td style="width:134px;">A-21208</td>
			<td style="width:174px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Laser Scanning Microscope&#160;</td>
			<td>Carl Zeiss</td>
			<td style="width:134px;"></td>
			<td style="width:174px;"></td>
		</tr>
	</tbody>
</table>

using en face immunofluorescence staining to observe vascular endothelial cells directly

Aberrant changes in endothelial phenotype and morphology are considered to be initial events in the pathogenesis of atherosclerosis. Direct observation of the intact endothelium will provide valuable information for understanding the cellular and molecular events in the dysfunctional endothelial cells. Here, we describe a modified en face immunofluorescence staining technique which enables scientists to obtain clear images of the intact endothelial surface and analyze the molecule expression patterns in situ. The method is simple and reliable for observing the entire endothelial monolayer at different sites of the aorta. This technique may be a promising tool for understanding the pathophysiology of atherosclerosis, especially at an early stage.

A 12-week-old C57BL/6 mouse was euthanized and perfused with normal saline containing 40 units/mL heparin and, then, prechilled 4% paraformaldehyde. The mouse aorta was exposed under a dissecting microscope (Figure 1), dissected, and cut open longitudinally (Figure 2). En face immunofluorescence staining of the vascular endothelial cells was performed as illustrated in Figure 3 and Table 1</s...

Watch this Scientific Journal Video about Using En Face Immunofluorescence Staining to Observe Vascular Endothelial Cells Directly at JoVE.com

Using En Face Immunofluorescence Staining to Observe Vascular Endothelial Cells Directly

Here, we present a protocol for immunofluorescence staining to observe the endothelial cells of the mouse aorta directly. This technique is useful when studying the cellular and molecular phenotype of endothelial cells in different flow patterns and in the development of atherosclerosis.

Aberrant changes in endothelial phenotype and morphology are considered to be initial events in the pathogenesis of atherosclerosis. Direct observation of ...

This protocol helps people analyze endothelial cell morphology, and the expression of molecules in regions, under different fluid shear stress. The main advantage of this technique is that it provides a direct assessment of vascular endothelial cells under different fluid shear stress. When performing this procedure, key steps are to use freshly prepared paraformaldehyde and to perform a good perfusion.Begin this procedure with anesthetization of a 12-week-old C57BL/6 mouse, as described in the text protocol. Confirm proper anesthetization by gently pinching the tail. Tape the mouse's paws to a stack of paper towels, with adhesive tape.Hold up the skin of the mouse with forceps, and cut the skin with a pair of scissors from the abdomen to the top of the thorax. Open the abdominal cavity, below the ribcage, with a sharp pair of scissors. Lift the sternum with forceps, and cut the diaphragm.Then cut away the ribcage to expose the thoracic cavity. Cut off the vena cava just above the liver with scissors. Pressure perfuse the arterial tree for five minutes, with pre-chilled normal saline containing 40 units per milliliter heparin, through the left ventricle, until the lungs and liver become pale.Then perfuse with pre-chilled 4%paraformaldehyde in PBS for four minutes. Remove all the muscles, organs, and fat, until the aorta is exposed. Place the mouse under a dissecting microscope.Use delicate forceps and a pair of delicate scissors to expose the aorta clearly under a dissecting microscope, and remove the connective tissue along the aorta, as cleanly as possible. Dissect the thoracic aorta from the heart to the celiac trunk with a pair of delicate scissors. Place the aorta into a six centimeter cell culture dish, with PBS.Cut open the aorta longitudinally, first along the lesser curve, and then use the microscissors to cut open the three branches of the aortic arch, including the innominate, left common carotid, and the left subclavian artery along the greater curve until the straight segment is met. Permeabilize the aorta with 1%polyoxyethylene octyl phenyl ether, in PBS for 10 minutes. Then block the aorta with 10%normal goat serum in tris-buffered saline containing 2.5%polysorbate 20 for one hour at room temperature, in a 12 well cell culture plate.Next incubate the aorta in the blocking buffer containing five grams per milliliter rabbit anti-VCAM1, and five grams per milliliter rat anti-VE-Cadherin, overnight at four degrees Celsius. After rinsing the sample three times with washing solution, apply the fluorescence conjugated secondary antibodies for one hour at room temperature, keeping in a dark place. Rinse another three times in the washing solution.Counterstain the aorta with DAPI for 10 minutes, keeping in a dark place. Then rinse the stained aorta three times in washing solution. Place the aorta on a cover slip with the lumenal surface downward, and move it slowly to antifade mounting solution that has been previously dropped on the cover slip.Gently stretch the aorta to keep the specimen flat. Invert the cover slip and put it on the glass slide. Take care to avoid any air bubbles between the specimen and the glass.Examine the aorta with a laser scanning confocal microscope. Analyze color intensities of different channels from the desired region in the en face images, with Image-Pro Plus software. En face immunofluorescence staining images of vascular endothelial cells from the mouse aorta are shown.En face immunofluorescence of the vascular cell adhesion protein one, and expression with VE-Cadherin as an endothelial marker, are shown under varying flow patterns from different regions of the mouse aorta. DAPI was also counterstained to show the cell nuclei for better visualization. When looking through the Z stacks under the microscope, the endothelial and smooth muscle cells can be easily distinguished by their cell nuclei morphology.The endothelial cell nuclei are oval shaped, and bigger than the spindle shaped, smooth muscle cell nuclei. Expression of VCAM-1 was more abundant in regions under disturbed flow, at lesser curvature of the aorta arch, compared with regions under steady flow, at greater curvature of the aorta arch, and at the thoracic aorta. Here areas of lesser curvature of a mouse aorta are indicated as d-flow areas, and the greater curvature and thoracic.With the right modification, this technique can be also applied to analysis of vascular permeability, and the position of macromolecules in the endothelial cell intima.

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Biology

Transplantation of Cells Directly into the Kidney of Adult Zebrafish

Regenerative medicine based on the transplantation of stem or progenitor cells into damaged tissues has the potential to treat a wide range of chronic diseases1. However, most organs are not easily accessible, necessitating the need to develop surgical methods to gain access to these structures. In this video article, we describe a method for transplanting cells directly into the kidney of adult zebrafish, a popular model to study regeneration and disease2. Recipient fish are pre-conditioned by irradiation to suppress the immune rejection of the injected cells3. We demonstrate how the head kidney can be exposed by a lateral incision in the flank of the fish, followed by the injection of cells directly in to the organ. Using fluorescently labeled whole kidney marrow cells comprising a mixed population of renal and hematopoietic precursors, we show that nephron progenitors can engraft and differentiate into new renal tissue - the gold standard of any cell-based regenerative therapy. This technique can be adapted to deliver purified stem or progenitor cells and/or small molecules to the kidney as well as other internal organs and further enhances the zebrafish as a versatile model to study regenerative medicine.

Cell transplantation is an essential technique for studying tissue regeneration and for developing cell-based therapies of disease. We demonstrate here a microsurgical technique that permits the transplantation of genetically labeled cells directly into the kidney of adult zebrafish fish.

Regenerative medicine based on the transplantation of stem or progenitor cells into damaged tissues has the potential to treat a wide range of chronic ...

Isolation and Differentiation of Stromal Vascular Cells to Beige/Brite Cells

Brown adipocytes have the ability to uncouple the respiratory chain in mitochondria and dissipate chemical energy as heat. Development of UCP1-positive brown adipocytes in white adipose tissues (so called beige or brite cells) is highly induced by a variety of environmental cues such as chronic cold exposure or by PPAR&gamma; agonists, therefore, this cell type has potential as a therapeutic target for obesity treatment. Although most immortalized adipocyte lines cannot recapitulate the process of "browning" of white fat in culture, primary adipocytes isolated from stromal vascular fraction in subcutaneous white adipose tissue (WAT) provide a reliable cellular system to study the molecular control of beige/brite cell development. Here we describe a protocol for effective isolation of primary preadipocytes and for inducing differentiation to beige/brite cells in culture. The browning effect can be assessed by the expression of brown fat-selective markers such as UCP1.

Primary white preadipocytes isolated from white adipose tissues in mice can be differentiated into beige/brite cells. Presented here is a reliable cellular model system to study the molecular regulation of "browning" of white fat.

Brown adipocytes have the ability to uncouple the  respiratory chain in mitochondria and dissipate chemical energy as heat.  Development of UCP1-positive ...

Robust 3D DNA FISH Using Directly Labeled Probes

3D DNA FISH has become a major tool for analyzing three-dimensional organization of the nucleus, and several variations of the technique have been published. In this article we describe a protocol which has been optimized for robustness, reproducibility, and ease of use. Brightly fluorescent directly labeled probes are generated by nick-translation with amino-allyldUTP followed by chemical coupling of the dye. 3D DNA FISH is performed using a freeze-thaw step for cell permeabilization and a heating step for simultaneous denaturation of probe and nuclear DNA. The protocol is applicable to a range of cell types and a variety of probes (BACs, plasmids, fosmids, or Whole Chromosome Paints) and allows for high-throughput automated imaging. With this method we routinely investigate nuclear localization of up to three chromosomal regions.

We describe a robust and versatile protocol for analyzing nuclear architecture by 3D DNA FISH using directly labeled fluorescent probes.

3D DNA FISH has become a major tool for  analyzing three-dimensional organization of the nucleus, and several variations  of the technique have been ...

Sonication-facilitated Immunofluorescence Staining of Late-stage Embryonic and Larval Drosophila Tissues In Situ

Studies performed in Drosophila melanogaster embryos and larvae provide crucial insight into developmental processes such as cell fate specification and organogenesis. Immunostaining allows for the visualization of developing tissues and organs. However, a protective cuticle that forms at the end of embryogenesis prevents permeation of antibodies into late-stage embryos and larvae. While dissection prior to immunostaining is regularly used to analyze Drosophila larval tissues, it proves inefficient for some analyses because small tissues may be difficult to locate and isolate. Sonication provides an alternative to dissection in larval Drosophila immunostaining protocols. It allows for quick, simultaneous processing of large numbers of late-stage embryos and larvae and maintains in situ morphology. After fixation in formaldehyde, a sample is sonicated. Sample is then subjected to immunostaining with antigen-specific primary antibodies and fluorescently labeled secondary antibodies to visualize target cell types and specific proteins via fluorescence microscopy. During the process of sonication, proper placement of a sonicating probe above the sample, as well as the duration and intensity of sonication, is critical. Additonal minor modifications to standard immunostaining protocols may be required for high quality stains. For antibodies with low signal to noise ratio, longer incubation times are typically necessary. As a proof of concept for this sonication-facilitated protocol, we show immunostains of three tissue types (testes, ovaries, and neural tissues) at a range of developmental stages.

Sonication-facilitated Immunofluorescence Staining of Late-stage Embryonic and Larval Drosophila Tissues In Situ

Immunostaining is an effective technique for visualizing specific cell types and proteins within tissues. By utilizing sonication, the protocol described here alleviates the need to dissect Drosophila melanogaster tissues from late-stage embryos and larvae before immunostaining. We provide an efficient methodology for the immunostaining of formaldehyde-fixed whole mount larvae.

Studies performed in Drosophila melanogaster embryos and larvae provide crucial insight into developmental processes such as cell fate specification and ...

Isolation of Murine Valve Endothelial Cells

Normal valve structures consist of stratified layers of specialized extracellular matrix (ECM) interspersed with valve interstitial cells (VICs) and surrounded by a monolayer of valve endothelial cells (VECs). VECs play essential roles in establishing the valve structures during embryonic development, and are important for maintaining life-long valve integrity and function. In contrast to a continuous endothelium over the surface of healthy valve leaflets, VEC disruption is commonly observed in malfunctioning valves and is associated with pathological processes that promote valve disease and dysfunction. Despite the clinical relevance, focused studies determining the contribution of VECs to development and disease processes are limited. The isolation of VECs from animal models would allow for cell-specific experimentation. VECs have been isolated from large animal adult models but due to their small population size, fragileness, and lack of specific markers, no reports of VEC isolations in embryos or adult small animal models have been reported. Here we describe a novel method that allows for the direct isolation of VECs from mice at embryonic and adult stages. Utilizing the Tie2-GFP reporter model that labels all endothelial cells with Green Fluorescent Protein (GFP), we have been successful in isolating GFP-positive (and negative) cells from the semilunar and atrioventricular valve regions using fluorescence activated cell sorting (FACS). Isolated GFP-positive VECs are enriched for endothelial markers, including CD31 and von Willebrand Factor (vWF), and retain endothelial cell expression when cultured; while, GFP-negative cells exhibit molecular profiles and cell shapes consistent with VIC phenotypes. The ability to isolate embryonic and adult murine VECs allows for previously unattainable molecular and functional studies to be carried out on a specific valve cell population, which will greatly improve our understanding of valve development and disease mechanisms.

The ability to isolate heart valve endothelial cells (VECs) is critical for understanding mechanisms of valve development, maintenance, and disease. Here we describe the isolation of VECs from embryonic and adult Tie2-GFP mice using FACS that will allow for studies determining the contribution of VECs in developmental and disease processes.

Normal valve structures consist of stratified layers of specialized extracellular matrix (ECM) interspersed with valve interstitial cells (VICs) and ...

Isolation and Primary Culture of Mouse Aortic Endothelial Cells

The vascular endothelium is essential to normal vascular homeostasis. Its dysfunction participates in various cardiovascular disorders. The mouse is an important model for cardiovascular disease research. This study demonstrates a simple method to isolate and culture endothelial cells from the mouse aorta without any special equipment. To isolate endothelial cells, the thoracic aorta is quickly removed from the mouse body, and the attached adipose tissue and connective tissue are removed from the aorta. The aorta is cut into 1 mm rings. Each aortic ring is opened and seeded onto a growth factor reduced matrix with the endothelium facing down. The segments are cultured in endothelial cell growth medium for about 4 days. The endothelial sprouting starts as early as day 2. The segments are then removed and the cells are cultured continually until they reach confluence. The endothelial cells are harvested using neutral proteinase and cultured in endothelial cell growth medium for another two passages before being used for experiments. Immunofluorescence staining indicated that after the second passage the majority of cells were double positive for Dil-ac-LDL uptake, Lectin binding, and CD31 staining, the typical characteristics of endothelial cells. It is suggested that cells at the second to third passages are suitable for in vitro and in vivo experiments to study the endothelial biology. Our protocol provides an effective means of identifying specific cellular and molecular mechanisms in endothelial cell physiopathology.

The vascular endothelial cells play a significant role in many important cardiovascular disorders. This article describes a simple method to isolate and expand endothelial cells from the mouse aorta without using any special equipment. Our protocol provides an effective means of identifying mechanisms in endothelial cell physiopathology.

The vascular endothelium is essential to normal vascular homeostasis. Its dysfunction participates in various cardiovascular disorders. The mouse is an ...

Indirect Immunofluorescence on Frozen Sections of Mouse Mammary Gland

Indirect immunofluorescence is used to detect and locate proteins of interest in a tissue. The protocol presented here describes a complete and simple method for the immune detection of proteins, the mouse lactating mammary gland being taken as an example. A protocol for the preparation of the tissue samples, especially concerning the dissection of mouse mammary gland, tissue fixation and frozen tissue sectioning, are detailed. A standard protocol to perform indirect immunofluorescence, including an optional antigen retrieval step, is also presented. The observation of the labeled tissue sections as well as image acquisition and post-treatments are also stated. This procedure gives a full overview, from the collection of animal tissue to the cellular localization of a protein. Although this general method can be applied to other tissue samples, it should be adapted to each tissue/primary antibody couple studied.

The indirect immunofluorescence protocol described in this article allows the detection and the localization of proteins in the mouse mammary gland. A complete method is given to prepare mammary gland samples, to perform immunohistochemistry, to image the tissue sections by fluorescence microscopy, and to reconstruct images.

Indirect immunofluorescence is used to detect and locate proteins of interest in a tissue. The protocol presented here describes a complete and simple ...

En Face Detection of Nitric Oxide and Superoxide in Endothelial Layer of Intact Arteries

Endothelium-derived nitric oxide (NO) produced from endothelial NO-synthase (eNOS) is one of the most important vasoprotective molecules in cardiovascular physiology. Dysfunctional eNOS such as uncoupling of eNOS leads to decrease in NO bioavailability and increase in superoxide anion (O2.&#8722;) production, and in turn promotes cardiovascular diseases. Therefore, appropriate measurement of NO and O2.&#8722; levels in the endothelial cells are pivotal for research on cardiovascular diseases and complications. Because of the extremely labile nature of NO and O2.&#8722;, it is difficult to measure NO and O2.&#8722; directly in a blood vessel. Numerous methods have been developed to measure NO and O2.&#8722; production. It is, however, either insensitive, or non-specific, or technically demanding and requires special equipment. Here we describe an adaption of the fluorescence dye method for en face simultaneous detection and visualization of intracellular NO and O2.&#8722; using the cell permeable diaminofluorescein-2 diacetate (DAF-2DA) and dihydroethidium (DHE), respectively, in intact aortas of an obesity mouse model induced by high-fat-diet feeding. We could demonstrate decreased intracellular NO and enhanced O2.&#8722; levels in the freshly isolated intact aortas of obesity mouse as compared to the control lean mouse. We demonstrate that this method is an easy technique for direct detection and visualization of NO and O2.&#8722; in the intact blood vessels and can be widely applied for investigation of endothelial (dys)function under (physio)pathological conditions.

En Face Detection of Nitric Oxide and Superoxide in Endothelial Layer of Intact Arteries

In this article we describe an adapted relatively easy method using the fluorescence dye diaminofluorescein-2 diacetate (DAF-2DA) and dihydroethidium (DHE) for en face simultaneous detection and visualization of intracellular nitric oxide (NO) and superoxide anion (O2.&#8722;) respectively, in freshly isolated intact aortas of an obesity mouse model.

Endothelium-derived nitric oxide (NO) produced from endothelial NO-synthase (eNOS) is one of the most important vasoprotective molecules in cardiovascular ...

A Simple Bioassay for the Evaluation of Vascular Endothelial Growth Factors

The analysis of receptor tyrosine kinases and their interacting ligands involved in vascular biology is often challenging due to the constitutive expression of families of related receptors, a broad range of related ligands and the difficulty of dealing with primary cultures of specialized endothelial cells. Here we describe a bioassay for the detection of ligands to the vascular endothelial growth factor receptor-2 (VEGFR-2), a key transducer of signals that promote angiogenesis and lymphangiogenesis. A cDNA encoding a fusion of the extracellular (ligand-binding) region of VEGFR-2 with the transmembrane and cytoplasmic regions of the erythropoietin receptor (EpoR) is expressed in the factor-dependent cell line Ba/F3. This cell line grows in the presence of interleukin-3 (IL-3) and withdrawal of this factor results in death of the cells within 24 hr. Expression of the VEGFR-2/EpoR receptor fusion provides an alternative mechanism to promote survival and potentially proliferation of stably transfected Ba/F3 cells in the presence of a ligand capable of binding and cross-linking the extracellular portion of the fusion protein (i.e., one that can cross-link the VEGFR-2 extracellular region). The assay can be performed in two ways: a semi-quantitative approach in which small volumes of ligand and cells permit a rapid result in 24 hr, and a quantitative approach involving surrogate markers of a viable cell number. The assay is relatively easy to perform, is highly responsive to known VEGFR-2 ligands and can accommodate extracellular inhibitors of VEGFR-2 signaling such as monoclonal antibodies to the receptor or ligands, and soluble ligand traps.

We describe a simple cell-based bioassay for detecting, quantifying and monitoring the activity of members of the vascular endothelial growth factor family of ligands. The assay uses chimeric receptors expressed in a factor-dependent cell line to provide a semi-quantitative or quantitative assessment of receptor binding and cross-linking by the ligand.

The analysis of receptor tyrosine kinases and their interacting ligands involved in vascular biology is often challenging due to the constitutive ...

En Face Preparation of Mouse Blood Vessels

Sections of paraffin embedded tissues are routinely used for studying tissue histology and histopathology. However, it is difficult to determine what the three-dimensional tissue morphology is from such sections. In addition, the sections of tissues examined may not contain the region within the tissue that is necessary for the purpose of the ongoing study. This latter limitation hinders histopathological studies of blood vessels since vascular lesions develop in a focalized manner. This requires a method that enables us to survey a wide area of the blood vessel wall, from its surface to deeper regions. A whole mount en face preparation of blood vessels fulfills this requirement. In this article, we will demonstrate how to make en face preparations of the mouse aorta and carotid artery and to immunofluorescently stain them for confocal microscopy and other types of fluorescence-based imaging.

En Face Preparation of Mouse Blood Vessels

A procedure for making en face preparations of the mouse carotid artery and aorta is described. Such preparations, when immunofluorescently stained with specific antibodies, enable us to study localization of proteins and identification of cell types within the entire vascular wall by confocal microscopy.

Sections of paraffin embedded tissues are routinely used for studying tissue histology and histopathology. However, it is difficult to determine what the ...