One day before the experiment:
<ol>
 <li>Allow BME (reduced growth factor, Cultrex, Trevigen) to thaw on ice or at 4&deg;C; once thawed keep on ice to prevent re-solidifying.</li>
</ol>
Day of the experiment:
<ol>
 <li>Mice (6-7 weeks old) are to be anesthetized and bled out.</li>
 <li>Remove thoracic aorta into a Petri dish filled with cold sterile PBS. </li>
 <li>Perform mechanical cleaning from surrounding fat tissue. Note, avoid drying of Aorta at any time.</li>
 <li>Using a surgical blade, slice Aorta evenly into 1 mm rings. The cut must be uniform and clean.</li>
 <li>Transfer rings to fresh cold PBS and keep on ice at all times.</li>
 <li>Using pre-cooled pipette tips, add to each well in a 48-well plate a rounded drop of 150 ml cold BME. Allow the BME drop to solidify at 37&deg;C for 20-30 minutes.</li>
 <li>Place a single aortic ring in the top center of each dome. Incubate for 10 minutes at 37&deg;C.</li>
 <li>On top of each ring add an additional 150 ml BME. Incubate for 20-30 minutes at 37&deg;C.</li>
 <li>Prepare medium: Human endothelial serum free medium (GIBCO, Carlsbad, CA) supplemented with 2% FCS, 50 units/ml penicillin and 50 &mu;g/ml streptomycin (Cellgro).</li>
 <li>To each well add 500 ml medium containing either:
 <ol class="lalpha">
 <li>Experimental samples.</li>
 <li>Positive control: Endothelial cell growth supplement (ECGS, final concentration 200 &mu;g/ml, BD Biosciences).</li>
 <li>Negative control: Medium alone.</li>
 </ol>
</li>
 <li>Incubate plate at 37&deg;C for 12 days, photograph rings between days 6 and 12 under standard phase contrast stereoscope.</li>
 <li>Optional: Collect supernatants.</li>
</ol>
Notes:
<ol>
 <li>Keep sterile conditions at all times.</li>
 <li>Avoid introduction of bubbles into the BME.</li>
</ol>

<ol>
	<li>Goodwin, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+assays+of+angiogenesis+for+assessment+of+angiogenic+and+anti-angiogenic+agents.">In vitro assays of angiogenesis for assessment of angiogenic and anti-angiogenic agents.</a> Microvascular Research. 74, 172-183 (2007).</li><li>Masson, V., Devy, L., Grignet-Debrus, C., Bernt, S., Bajou, K., Blacher, S., Roland, G., Chang, Y., Fong, T., Carmeliet, P., Foidart, J. M., Noel, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mouse+aortic+ring+assay:+a+new+approach+of+the+molecular+genetics+of+angiogenesis.">Mouse aortic ring assay: a new approach of the molecular genetics of angiogenesis.</a> Biol. Proced. Online. 4, 24-31 (2002).</li></ol>

Aortic ring assay is a beneficial tool on the way to evaluate angiogenic as well as anti-angiogenic factors. The vessels that grow out from aortic rings recruit smooth muscle cells and pericytes to associate with the endothelial cell tube, meaning that they are anatomically similar to neovessels in vivo. Furthermore, the mouse aortic ring assay holds the advantage of the vast array of transgenic tools available for this species. Yet, there are several disadvantages to the aortic ring assay. First, vessels outgro...

aortic ring assay

Angiogenesis, the sprouting of blood vessels from preexisting vasculature is associated with both natural and pathological processes. Various angiogenesis assays involve the study of individual endothelial cells in culture conditions (1). The aortic ring assay is an angiogenesis model that is based on organ culture. In this assay, angiogenic vessels grow from a segment of the aorta (modified from (2)). Briefly, mouse thoracic aorta is excised, the fat layer and adventitia are removed, and rings approximately 1 mm in length are prepared. Individual rings are then embedded in a small solid dome of basement matrix extract (BME), cast inside individual wells of a 48-well plate. Angiogenic factors and inhibitors of angiogenesis can be directly added to the rings, and a mixed co-culture of aortic rings and other cell types can be employed for the study of paracrine angiogenic effects. Sprouting is observed by inspection under a stereomicroscope over a period of 6-12 days. Due to the large variation caused by the irregularities in the aortic segments, experimentation in 6-plicates is strongly advised. Neovessel outgrowth is monitored throughout the experiment and imaged using phase microscopy, and supernatants are collected for measurement of relevant angiogenic and anti-angiogenic factors, cell death markers and nitrite.

Watch this Scientific Journal Video about Aortic Ring Assay at JoVE.com

Aortic Ring Assay

Angiogenesis, the sprouting of blood vessels from pre-existing vasculature, is associated with both natural and pathological processes. Here we demonstrate an aortic ring assay that allows angiogenic potentiators and inhibitors to be directly added to aortic rings in culture. Sprouting and neovessel outgrowth can be determined by inspecting the aortic rings over a period of 6-12 days.

Angiogenesis, the sprouting of blood vessels from preexisting vasculature is associated with both natural and pathological processes. Various angiogenesis ...

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30.9K Views.  Ben-Gurion University. Angiogenesis, the sprouting of blood vessels from pre-existing vasculature, is associated with both natural and pathological processes. Here we demonstrate an aortic ring assay that allows angiogenic potentiators and inhibitors to be directly added to aortic rings in culture. Sprouting and neovessel outgrowth can be determined by inspecting the aortic rings over a period of 6-12 days.

Video: Aortic Ring Assay

Creation of Murine Experimental Abdominal Aortic Aneurysms with Elastase 

Transient intraluminal infusion of porcine pancreatic elastase into the infrarenal segment of the abdominal aorta is the most widely used animal model of abdominal aortic aneurysm (AAA) ever since it was first described in rats by Anidjar and colleagues.1 The rationale for its development was based on the disrupted nature of elastin observed in AAAs. This rat model has been modified to produce AAAs in the infrarenal aortic region of mice.2 The model has the ability to add broad insight into the pathobiology of AAA due to the emergence of numerous transgenic and gene knockout mice. Moreover, it is a viable platform to test potential therapeutic agents for AAA. In this video, we demonstrate the elastase infusion AAA procedure used in our laboratory. 
Mice are anesthetized using 2.5% isoflurane, and a laparotomy is performed under sterile conditions. The abdominal aortais isolated with the assistance of an operating stereomicroscope (Leica). After placing temporary ligatures around the proximal and distal aorta, an aortotomy is created at the bifurcation with the tip of a 30-gauge needle. A heat-tapered segment of PE-10 polyethylene tubing is introduced through the aortotomy and secured. The aortic lumen is subsequently perfused for 5-15 minutes at 100 mm Hg with saline containing type I porcine pancreatic elastase (4.5 U/mL; Sigma Chemical Co.). After removing the perfusion catheter, the aortotomy is repaired without constriction of the lumen.

Creation of Murine Experimental Abdominal Aortic Aneurysms with Elastase

This video shows how to induce abdominal aortic aneurysms (AAA) in mice via transient intraluminal infusion of porcine pancreatic elastase into the infrarenal segment of the abdominal aorta. The model has the ability to add broad insight into the pathobiology of AAA due to the emergence of numerous transgenic and gene knockout mice.

Transient intraluminal infusion of porcine pancreatic elastase into the infrarenal segment of the abdominal aorta is the most widely used animal model of ...

Transverse Aortic Constriction in Mice

Transverse aortic constriction (TAC) in the mouse is a commonly used experimental model for pressure overload-induced cardiac hypertrophy and heart failure.1 TAC initially leads to compensated hypertrophy of the heart, which often is associated with a temporary enhancement of cardiac contractility. Over time, however, the response to the chronic hemodynamic overload becomes maladaptive, resulting in cardiac dilatation and heart failure.2 The murine TAC model was first validated by Rockman et al.1, and has since been extensively used as a valuable tool to mimic human cardiovascular diseases and elucidate fundamental signaling processes involved in the cardiac hypertrophic response and heart failure development. When compared to other experimental models of heart failure, such as complete occlusion of the left anterior descending (LAD) coronary artery, TAC provides a more reproducible model of cardiac hypertrophy and a more gradual time course in the development of heart failure. Here, we describe a step-by-step procedure to perform surgical TAC in mice. To determine the level of pressure overload produced by the aortic ligation, a high frequency Doppler probe is used to measure the ratio between blood flow velocities in the right and left carotid arteries.3, 4 With surgical survival rates of 80-90%, transverse aortic banding is an effective technique of inducing left ventricular hypertrophy and heart failure in mice.

Transverse aortic constriction (TAC) in the mouse is a commonly used experimental model to study mechanisms underlying cardiac hypertrophy and heart failure development. Here, we describe procedures to constrict the aorta to create a reproducible degree of cardiac hypertrophy in mice.

Transverse aortic constriction (TAC) in the mouse is a commonly used experimental model for pressure overload-induced cardiac hypertrophy and heart ...

Na&iuml;ve Adult Stem Cells Isolation from Primary Human Fibroblast Cultures

Over the last decade, several adult stem cell populations have been identified in human skin 1-4. The isolation of multipotent adult dermal precursors was first reported by Miller F. D laboratory 5, 6. These early studies described a multipotent precursor cell population from adult mammalian dermis 5. These cells--termed SKPs, for skin-derived precursors-- were isolated and expanded from rodent and human skin and differentiated into both neural and mesodermal progeny, including cell types never found in skin, such as neurons 5. Immunocytochemical studies on cultured SKPs revealed that cells expressed vimentin and nestin, an intermediate filament protein expressed in neural and skeletal muscle precursors, in addition to fibronectin and multipotent stem cell markers 6. Until now, the adult stem cells population SKPs have been isolated from freshly collected mammalian skin biopsies.
Recently, we have established and reported that a population of skin derived precursor cells could remain present in primary fibroblast cultures established from skin biopsies 7. The assumption that a few somatic stem cells might reside in primary fibroblast cultures at early population doublings was based upon the following observations: (1) SKPs and primary fibroblast cultures are derived from the dermis, and therefore a small number of SKP cells could remain present in primary dermal fibroblast cultures and (2) primary fibroblast cultures grown from frozen aliquots that have been subjected to unfavorable temperature during storage or transfer contained a small number of cells that remained viable 7. These rare cells were able to expand and could be passaged several times. This observation suggested that a small number of cells with high proliferation potency and resistance to stress were present in human fibroblast cultures 7.
We took advantage of these findings to establish a protocol for rapid isolation of adult stem cells from primary fibroblast cultures that are readily available from tissue banks around the world (Figure 1). This method has important significance as it allows the isolation of precursor cells when skin samples are not accessible while fibroblast cultures may be available from tissue banks, thus, opening new opportunities to dissect the molecular mechanisms underlying rare genetic diseases as well as modeling diseases in a dish.

Na&amp;#239;ve Adult Stem Cells Isolation from Primary Human Fibroblast Cultures

We report a method to isolate na&#239;ve multipotent skin-derived precursor (SKP) cells from primary human fibroblast cultures. We show that these SKPs derived from fibroblast cultures share similar stem cell properties to the ones derived directly from human skin biopsies. These cells express the neural crest marker, nestin, in addition to the multipotent markers such as OCT4 and Nanog.

Over the last decade, several adult stem cell  populations have been identified in human skin 1-4.  The isolation of multipotent adult dermal precursors ...

Super-resolution Imaging of the Cytokinetic Z Ring in Live Bacteria Using Fast 3D-Structured Illumination Microscopy (f3D-SIM)

Imaging of biological samples using fluorescence microscopy has advanced substantially with new technologies to overcome the resolution barrier of the diffraction of light allowing super-resolution of live samples. There are currently three main types of super-resolution techniques &#8211; stimulated emission depletion (STED), single-molecule localization microscopy (including techniques such as PALM, STORM, and GDSIM), and structured illumination microscopy (SIM). While STED and single-molecule localization techniques show the largest increases in resolution, they have been slower to offer increased speeds of image acquisition. Three-dimensional SIM (3D-SIM) is a wide-field fluorescence microscopy technique that offers a number of advantages over both single-molecule localization and STED. Resolution is improved, with typical lateral and axial resolutions of 110 and 280 nm, respectively and depth of sampling of up to 30 &#181;m from the coverslip, allowing for imaging of whole cells. Recent advancements (fast 3D-SIM) in the technology increasing the capture rate of raw images allows for fast capture of biological processes occurring in seconds, while significantly reducing photo-toxicity and photobleaching. Here we describe the use of one such method to image bacterial cells harboring the fluorescently-labelled cytokinetic FtsZ protein to show how cells are analyzed and the type of unique information that this technique can provide.

Super-resolution Imaging of the Cytokinetic Z Ring in Live Bacteria Using Fast 3D-Structured Illumination Microscopy f3D-SIM

Spatiotemporal information about dynamic proteins inside live cells is crucial for understanding biology. A type of super-resolution microscopy called fast 3D-structured illumination microscopy (f3D-SIM) reveals unique information about the cytokinetic Z ring in bacteria: both its bead-like appearance and the rapid dynamics of FtsZ within the ring.

Imaging of biological samples using fluorescence microscopy has advanced substantially with new technologies to overcome the resolution barrier of the ...

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 ...

Differentiation Capacity of Human Aortic Perivascular Adipose Progenitor Cells

Adipose tissue is a rich source of multi-potent mesenchymal stem cells (MSC) capable of differentiating into osteogenic, adipogenic, and chondrogenic lineages. Adipogenic differentiation of progenitor cells is a major mechanism driving adipose tissue expansion and dysfunction in response to obesity. Understanding changes to perivascular adipose tissue (PVAT) is thus clinically relevant in metabolic disease. However, previous studies have been predominately performed in the mouse and other animal models. This protocol uses human thoracic PVAT samples collected from patients undergoing coronary artery bypass graft surgery. Adipose tissue from the ascending aorta was collected and used for explantation of the stromal vascular fraction. We previously confirmed the presence of adipose progenitor cells in human PVAT with the capacity to differentiate into lipid-containing adipocytes. In this study, we further analyzed the differentiation potential of cells from the stromal vascular fraction, presumably containing multi-potent progenitor cells. We compared PVAT-derived cells to human bone marrow MSC for differentiation into adipogenic, osteogenic, and chondrogenic lineages. Following 14 days of differentiation, specific stains were utilized to detect lipid accumulation in adipocytes (Oil red O), calcific deposits in osteogenic cells (Alizarin Red), or glycosaminoglycans and collagen in chondrogenic cells (Masson&#8217;s Trichrome). While bone marrow MSC efficiently differentiated into all three lineages, PVAT-derived cells had adipogenic and chondrogenic potential, but lacked robust osteogenic potential.

The goal of this protocol is to test the ability of progenitor cells derived from human perivascular adipose tissue to differentiate into multiple cell lineages. Differentiation was compared to mesenchymal stem cells derived from human bone marrow, which is known to differentiate into adipocyte, osteocyte, and chondrocyte lineages.

Adipose tissue is a rich source of multi-potent mesenchymal stem cells (MSC) capable of differentiating into osteogenic, adipogenic, and chondrogenic ...

Isolation and Culture of Primary Aortic Endothelial Cells from Miniature Pigs

Xenotransplantation is a promising way to resolve the shortage of human organs for patients with end-stage organ failure, and the pig is considered as a suitable organ source. Immune rejection and coagulation are two major hurdles for the success of xenotransplantation. Vascular endothelial cell (EC) injury and dysfunction are important for the development of the inflammation and coagulation responses in xenotransplantation. Thus, isolation of porcine aortic endothelial cells (pAECs) is necessary for investigating the immune rejection and coagulation responses. Here, we have developed a simple enzymatic approach for the isolation, characterization, and expansion of highly purified pAECs from miniature pigs. First, the miniature pig was anaesthetized with ketamine, and a length of aorta was excised. Second, the endothelial surface of aorta was exposed to 0.005% collagenase IV digestive solution for 15 min. Third, the endothelial surface of the aorta was scraped in only one direction with a cell scraper (&#60;10 times), and was not compressed during the process of scraping. Finally, the isolated pAECs of Day 3, and after passage 1 and passage 2, were identified by flow cytometry with an anti-CD31 antibody. The percentages of CD31-positive cells were 97.4% &#177; 1.2%, 94.4% &#177; 1.1%, and 92.4% &#177; 1.7% (mean &#177; SD), respectively. The concentration of Collagenase IV, the digestive time, the direction, and frequency and intensity of scraping are critical for decreasing fibroblast contamination and obtaining high-purity and a large number of ECs. In conclusion, our enzymatic method is a highly-effctive method for isolating ECs from the miniature pig aorta, and the cells can be expanded in vitro to investigate the immune and coagulation responses in xenotransplantation.

An effective enzymatic method for isolation of primary porcine aortic endothelial cells (pAECs) from miniature pigs is described. The isolated primary pAECs can be used to investigate the immune and coagulation response in xenotransplantation.

Xenotransplantation is a promising way to resolve the shortage of human organs for patients with end-stage organ failure, and the pig is considered as a ...

Isolation of Primary Patient-specific Aortic Smooth Muscle Cells and Semiquantitative Real-time Contraction Measurements In Vitro

Smooth muscle cells (SMCs) are the predominant cell type in the aortic media. Their contractile machinery is important for the transmission of force in the aorta and regulates vasoconstriction and vasodilation. Mutations in genes encoding for the SMC contractile apparatus proteins are associated with aortic diseases, such as thoracic aortic aneurysms. Measuring SMC contraction in vitro is challenging, especially in a high-throughput manner, which is essential for screening patient material. Currently available methods are not suitable for this purpose. This paper presents a novel method based on electric cell-substrate impedance sensing (ECIS). First, an explant protocol is described to isolate patient-specific human primary SMCs from aortic biopsies and patient-specific human primary dermal fibroblasts for the study of aortic aneurysms. Next, a detailed description of a new contraction method is given to measure the contractile response of these cells, including the subsequent analysis and suggestion for comparing different groups. This method can be used to study the contraction of adherent cells in the context of translational (cardiovascular) studies and patient and drug screening studies.

Isolation of Primary Patient-specific Aortic Smooth Muscle Cells and Semiquantitative Real-time Contraction Measurements In Vitro

This paper describes an explant culture-based method for the isolation and culturing of primary, patient-specific human aortic smooth muscle cells and dermal fibroblasts. Furthermore, a novel method is presented for measuring cell contraction and subsequent analysis, which can be used to study patient-specific differences in these cells.

Smooth muscle cells (SMCs) are the predominant cell type in the aortic media. Their contractile machinery is important for the transmission of force in ...

Mouse Abdominal Aortic Aneurysm Model Induced by Perivascular Application of Elastase

Abdominal aortic aneurysm (AAA), although primarily asymptomatic, is potentially life-threatening as the rupture of AAA usually has a devastating outcome. Currently, there are several distinct experimental models of AAA, each emphasizing a different aspect in the pathogenesis of AAA. The elastase-induced AAA model is the second most used rodent AAA model. This model involves direct infusion or application of porcine pancreatic elastase (PPE) to the infrarenal segment of the aorta. Due to technical challenges, most elastase-induced AAA model nowadays is performed with the external application rather than an intraluminal infusion of PPE. The infiltration of elastase will cause degradation of elastic lamellae in the medial layers, resulting in the loss of aortic wall integrity and subsequent dilation of the abdominal aorta. However, one disadvantage of the elastase-induced AAA model is the inevitable variation of how the surgery is performed. Specifically, the surgical technique of isolating the infrarenal segment of the aorta, the material used for aorta wrapping and PPE incubation, the enzymatic activity of PPE, and the time duration of PPE application can all be important determinants that affect the eventual AAA formation rate and aneurysm diameter. Notably, the difference in these factors from different studies on AAA can lead to reproducibility issues. This article describes a detailed surgical process of the elastase-induced AAA model through direct application of PPE to the adventitia of the infrarenal abdominal aorta in the mouse. Following this procedure, a stable AAA formation rate of around 80% in male and female mice is achievable. The consistency and reproducibility of AAA studies using an elastase-induced AAA model can be significantly enhanced by establishing a standard surgical procedure.

The present protocol describes a standardized surgical method for the elastase-induced AAA model through the direct application of elastase to the adventitia of infrarenal abdominal aorta in mice.

Abdominal aortic aneurysm (AAA), although primarily asymptomatic, is potentially life-threatening as the rupture of AAA usually has a devastating outcome. ...

A Modified Technique for Transverse Aortic Constriction in Mice

Transverse aortic constriction (TAC) is a frequently used surgery in research regarding heart failure and cardiac hypertrophy based on the formation of pressure overload in mouse models. The main challenge of this procedure is to clearly visualize the transverse aortic arch and precisely band the target vessel. Classical approaches perform a partial thoracotomy to expose the transverse aortic arch. However, it is an open-chest model that causes a rather large surgical trauma and requires a ventilator during the surgery. To prevent unnecessary trauma and simplify the operating procedure, the aortic arch is approached via the proximal proportion of the sternum, reaching and binding the target vessel using a small self-made retractor that contains a snare. This procedure can be conducted without entering the pleura cavity and does not need a ventilator or microsurgical operation, which leaves the mice with physiological breathing patterns, simplifies the procedure, and significantly reduces operation time. Due to the less invasive approach and less operation time, mice can undergo fewer stress reactions and recover rapidly.

The present protocol describes a modified and simplified technique with a minimally invasive transverse aortic constriction (TAC) procedure using a self-made retractor. This procedure can be conducted without a ventilator or microscope and introduces pressure overload, eventually leading to cardiac hypertrophy or heart failure.

Transverse aortic constriction (TAC) is a frequently used surgery in research regarding heart failure and cardiac hypertrophy based on the formation of ...