We would like to acknowledge the University Research Facility in Life Sciences (ULS) of The Hong Kong Polytechnic University for the provision of Vevo 2100 ultrasound system. Special thanks to Dr. Chunyi Wen from the Interdisciplinary Division of Biomedical Engineering, Hong Kong Polytechnic University, for training and facilitation. This work was supported by HK government RGC Grant GRF 17127215, 764812 and HKU6/CRF/11G to Billy K C Chow.

The protocol follows the guidelines of the Committee on the Use of Live Animals in Teaching and Research (CULATR) at the University of Hong Kong.
1. Operation Site Preparation
<ol>
	<li>Disinfect the operation site with 75% isopropyl alcohol. Adjust the heating pad temperature to 37 &#176;C to avoid changes in heart and respiratory rates of the subject animal.</li>
	<li>Use surgical instruments sterilized in a gravity displacement sterilizer at 121 &#176;C for 30 min or by other appropriate methods.</li>
	<li>Take 2 - 4 30-gauge needles and curve them with a needle holder, as seen in Figure 1, to make a tool for ligation and tissue separation and for use as a retractor. Mount the now-curved needle on a cotton applicator for use in surgery.</li>
	<li>Blunt a 27-gauge needle and curve it 90&#186; with the needle holder. Smooth the tip by rubbing a hard surface to make a 0.4-mm spacer in ligation step.</li>
</ol>
2. Animal Preparation
<ol>
	<li>Anesthetize a 2-month-old, male, 22-25 g C57BL/6N mouse with an appropriate ketamine and xylazine mixture in relation to body weight: 100 mg/kg + 10 mg/kg i.p. Confirm the anesthetization with the negative tail pinch reflex.</li>
	<li>Remove the hair on the anterior neck and chest with a 2- to 3-min application of depilatory cream. Remove the cream with warm water and a cotton applicator.</li>
	<li>Apply ophthalmic ointment or gel to the eyes of the animal to prevent the drying out of the cornea.</li>
	<li>Place the animal on a heating pad in the supine position and conduct intra-operative monitoring, being sure to keep appropriate documentation at every 15-min interval.</li>
	<li>Use surgical paper tape to secure the limbs to the heating pad in order to keep the animal in the correct position during the surgery.</li>
	<li>Disinfect the skin alternately with alcohol and povidone-iodine solution three times.</li>
	<li>Use a sterile drape with an exposed operation field to prevent contamination. Use new sterile gloves for each mouse and as necessary.</li>
</ol>
3. Ligation Procedure
<ol>
	<li>Open the skin of the mouse at the midline position of the neck and chest with a scalpel.</li>
	<li>Pull the thyroid gland towards the head by gently separating connective tissues with blunt scissors.</li>
	<li>Separate the muscle layer on the trachea at the midline towards both sides with the curved needles.</li>
	<li>Using the blunt scissors, cut the sternum to the second rib (approximately 5 mm). Open the cut with a retractor or curved forceps.</li>
	<li>Separate the thymus lobes from one another and the lower chest wall by separating the connective tissue with the curved needle; the transverse aortic arch and two carotid arteries will be clearly visible at this point.</li>
	<li>Place the curved needle under the arch and perforate between the vessel wall and connective tissue on the other side by pushing the curved head out.</li>
	<li>Using the curved needle, pull the 6-0 monofilament suture under the aortic arch.</li>
	<li>Place the spacer in the loop and fix the suture in place with a double-knot. Remove the spacer gently.</li>
	<li>Confirm a successful constriction with the knot position and cut the ends of the suture.</li>
	<li>Close the chest wall using 6/0 silk suture with a simple interrupted suture pattern. Close the skin with a 6/0 monofilament suture in a continuous suture pattern.</li>
</ol>
4. Post-operative Care
<ol>
	<li>Apply povidone-iodine solution to the suture site and place the animal in a pre-warmed cage for recovery and post-operative monitoring.</li>
	<li>Inject buprenorphine (0.05 - 0.1 mg/kg s.c. every 12 h) after the animal has regained consciousness to relieve pain and provide the mouse with appropriate soft food.</li>
	<li>Return the animal to a 12-h light/dark cycle room after full recovery.</li>
</ol>
5. Echocardiography: Confirmation of Successful Ligation and Measurements
<ol>
	<li>After one week, anesthetize the previously banded mouse with 3 - 5% isoflurane, for induction, and 1 - 1.5%, for maintenance, with a 1 L/min oxygen flow rate.</li>
	<li>Remove the chest hair using depilatory cream. Thoroughly remove the cream with warm water and a cotton applicator.</li>
	<li>Secure the mouse in the supine position to the animal-handling platform, maintained at 37 &#176;C. Apply electrode gel to the paws and tape them to the pad with electrodes.</li>
	<li>Apply ultrasound gel to the mouse chest. With a 40-MHz MS550D probe and a high-frequency ultrasound system, perform color Doppler and pulsed-wave Doppler scanning on the left and right carotid arteries, as well as on the aortic arch.</li>
	<li>Using B-Mode, locate the left ventricle. Using M-Mode, the systolic and diastolic wall thickness can be measured. Use Cine Store and Frame Store to save data and images as required.</li>
	<li>Using B-Mode, locate the left common carotid artery before the branching point. Use pulsed-wave and color Doppler to evaluate the flow. Repeat with the right carotid artery at a similar point. Save the images in Cine Store and Frame Store modes to analyze later.</li>
	<li>Tilt the animal-handling platform to the far left so that the mouse is in the left decubitus position. Place the probe on the mouse, 30&#176; offset from a position parallel to the head at the parasternal position, and manipulate X and Y to find the aortic arch.</li>
	<li>Locate the constriction. Use color Doppler mode to make the site of the constriction more visible, as blood will be flowing through a narrow channel between the point where the two carotid arteries branch out from the aortic arch.</li>
	<li>Use pulsed-wave and color Doppler to measure the peak flow velocity. Use Cine Store and Frame Store to save data and images as required.</li>
	<li>Allow the animal to recover on a heating pad in the prone position. Return the animal to the original cage in a 12-h light/dark cycle room after it has fully recovered from anesthesia.</li>
</ol>

<ol>
	<li>Rockman, H. 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=Segregation+of+atrial-specific+and+inducible+expression+of+an+atrial+natriuretic+factor+transgene+in+an+in+vivo+murine+model+of+cardiac+hypertrophy.">Segregation of atrial-specific and inducible expression of an atrial natriuretic factor transgene in an in vivo murine model of cardiac hypertrophy.</a> Proc Natl Acad Sci U S A. 88 (18), 8277-8281 (1991).</li><li>de Almeida, A. C., van Oort, R. J., Wehrens, X. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transverse+aortic+constriction+in+mice.">Transverse aortic constriction in mice.</a> J Vis Exp. (38), (2010).</li><li>Hu, P., 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=Minimally+invasive+aortic+banding+in+mice:+effects+of+altered+cardiomyocyte+insulin+signaling+during+pressure+overload.">Minimally invasive aortic banding in mice: effects of altered cardiomyocyte insulin signaling during pressure overload.</a> Am J Physiol Heart Circ Physiol. 285 (3), H1261-H1269 (2003).</li><li>Shimizu, I., 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=Excessive+cardiac+insulin+signaling+exacerbates+systolic+dysfunction+induced+by+pressure+overload+in+rodents.">Excessive cardiac insulin signaling exacerbates systolic dysfunction induced by pressure overload in rodents.</a> J Clin Invest. 120 (5), 1506-1514 (2010).</li><li>Tarnavski, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mouse+surgical+models+in+cardiovascular+research.">Mouse surgical models in cardiovascular research.</a> Methods Mol Biol. 573, 115-137 (2009).</li><li>Zhang, X., 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+modified+murine+model+for+the+study+of+reverse+cardiac+remodelling.">A modified murine model for the study of reverse cardiac remodelling.</a> Exp Clin Cardiol. 18 (2), e115-e117 (2013).</li><li>Hartley, C. 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=Doppler+estimation+of+reduced+coronary+flow+reserve+in+mice+with+pressure+overload+cardiac+hypertrophy.">Doppler estimation of reduced coronary flow reserve in mice with pressure overload cardiac hypertrophy.</a> Ultrasound Med Biol. 34 (6), 892-901 (2008).</li><li>Scherrer-Crosbie, M., Thibault, H. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Echocardiography+in+translational+research:+of+mice+and+men.">Echocardiography in translational research: of mice and men.</a> J Am Soc Echocardiogr. 21 (10), 1083-1092 (2008).</li><li>Faerber, G., 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=Induction+of+heart+failure+by+minimally+invasive+aortic+constriction+in+mice:+reduced+peroxisome+proliferator-activated+receptor+gamma+coactivator+levels+and+mitochondrial+dysfunction.">Induction of heart failure by minimally invasive aortic constriction in mice: reduced peroxisome proliferator-activated receptor gamma coactivator levels and mitochondrial dysfunction.</a> J Thorac Cardiovasc Surg. 141 (2), 492-500 (2011).</li><li>Li, L., 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=Assessment+of+Cardiac+Morphological+and+Functional+Changes+in+Mouse+Model+of+Transverse+Aortic+Constriction+by+Echocardiographic+Imaging.">Assessment of Cardiac Morphological and Functional Changes in Mouse Model of Transverse Aortic Constriction by Echocardiographic Imaging.</a> J Vis Exp. (112), (2016).</li></ol>

The authors declare that they have no competing financial interests.

Rockman and colleagues devised the first method for aortic banding as a method to study pressure overload in the heart. This enabled research to begin to uncover the cellular and molecular consequences of hypertension and heart failure1. An improved method, minimally invasive transverse aortic constriction (MTAC), provides an amenable, time-dependent method for the induction of left ventricular pressure overload and heart failure, without the drawbacks of the conventional transverse aortic constri...

The overall purpose of this article is to demonstrate how transverse aortic constriction (TAC) in mice can be modified to produce a simpler and more expedient surgery. TAC was first introduced in 19911 and enabled molecular biologists to study the cellular and molecular pathways that lead to hypertrophy in the left ventricle and to heart failure, particularly in small animals with manipulated genomes2,3,4,5,6. Despite its efficacy at producing the desired pressure overload, the technique is ultimately limited by the difficulty in performing the procedure and by its low survival rate. A surgeon conducting TAC must be able to perform endotracheal intubation, thoracotomy, and use artificial ventilation in order to prevent lung collapse1.
Oftentimes, a simple and less invasive method is desired. As a consequence, minimally invasive transverse aortic constriction (MTAC) was devised3. Though the outcome (specifically, left ventricular hypertrophy) is the same, the procedure involves significantly fewer apparatuses and less damage to the animal. MTAC proves to be a desirable method that has a greater survival rate, above 90%, and has an operation time of only 15 to 25 min. The infrequent cases of death after successful surgery can be attributable to too-tight constriction of the aortic arch, resulting in tremendous left ventricular overload and fatal reduction of blood supply to critical organs such as the kidneys.
After the procedure is completed, echocardiography can be used to evaluate the success of banding and the cardiac morphology and function. A high-frequency ultrasound system can be utilized to measure the diameter and flow changes in the left and right carotid arteries, to visualize the aortic arch constriction for peak flow velocity measurements, and to determine the left ventricle wall thickness and functional parameters7,8. After euthanasia, the organs can also be collected for histopathological studies with hematoxylin and eosin staining and Picrosirius collagen staining, the latter being particularly useful for the observation of fibrosis.

<table><tbody><tr><td>&lt;strong&gt;1 inch 30 Gauge Needles&lt;/strong&gt;</td><td>BD, Franklin Lakes, NJ 07417, USA.&amp;nbsp;</td><td>305128</td><td>Curved as in the procedure and &lt;strong&gt;Figure 1&lt;/strong&gt;</td></tr><tr><td>&lt;strong&gt;27 Gauge Needle&lt;/strong&gt;</td><td>BD, Franklin Lakes, NJ 07417, USA.&amp;nbsp;</td><td>301629</td><td>Make blunt and smooth for spacer</td></tr><tr><td>&lt;strong&gt;6/0 Dafilon&lt;/strong&gt;</td><td>B. Braun, 34212 Melsungen, Hessen, Germany.</td><td>C0933066</td><td></td></tr><tr><td>&lt;strong&gt;6/0 Silkam&lt;/strong&gt;</td><td>B. Braun, 34212 Melsungen, Hessen, Germany.</td><td>C0762067</td><td></td></tr><tr><td>&lt;strong&gt;Sterile gloves&lt;/strong&gt;</td><td>A.R. Medicom, Inc (Asia), Hong Kong.</td><td></td><td></td></tr><tr><td>&lt;strong&gt;Cotton Applicator&lt;/strong&gt;</td><td>Mannings, Quarry Bay, Hong Kong.</td><td></td><td>Local Shopping Center</td></tr><tr><td>&lt;strong&gt;Depilatory Cream&lt;/strong&gt;</td><td>Veet (Hong Kong), Kwun Tong, Kowloon, Hong Kong</td><td></td><td>Local Shopping Center</td></tr><tr><td>&lt;strong&gt;Lexer-Baby Scissor&lt;/strong&gt;</td><td>FST, British Columbia V7H 0A6, Canada.</td><td>14078-10</td><td></td></tr><tr><td>&lt;strong&gt;Curved Iris Forcep&lt;/strong&gt;</td><td>FST, British Columbia V7H 0A6, Canada.</td><td>11065-07</td><td></td></tr><tr><td>&lt;strong&gt;Micro Olsen-Hegar Needle Holder&lt;/strong&gt;</td><td>WPI, Sarasota, FL 34240, USA.&amp;nbsp;</td><td>501989</td><td></td></tr><tr><td>&lt;strong&gt;Stereo Micrioscope&lt;/strong&gt;</td><td>WPI, Sarasota, FL 34240, USA.&amp;nbsp;</td><td>PZMIII-BS</td><td></td></tr><tr><td>&lt;strong&gt;GenTeal Eye Gel&lt;/strong&gt;</td><td>Novartis, East Hanover, NJ 07936, USA.&amp;nbsp;</td><td></td><td>Local Pharmacy</td></tr><tr><td>&lt;strong&gt;Heating Pad&lt;/strong&gt;</td><td>Kent Scientific Corporation, Torrington, CT 06790, USA.&amp;nbsp;</td><td>DCT-20</td><td></td></tr><tr><td>&lt;strong&gt;Surgical tape&lt;/strong&gt;</td><td>Laboratory Animal Unit</td><td></td><td></td></tr><tr><td>&lt;strong&gt;Ketamine and Xylazine&lt;/strong&gt;</td><td>Laboratory Animal Unit</td><td></td><td></td></tr><tr><td>&lt;strong&gt;Betadine&lt;/strong&gt;</td><td>Laboratory Animal Unit</td><td></td><td></td></tr><tr><td>&lt;strong&gt;Buprenorphine&lt;/strong&gt;</td><td>Laboratory Animal Unit</td><td></td><td></td></tr></tbody></table>

minimally invasive transverse aortic constriction in mice

Minimally invasive transverse aortic constriction (MTAC) is a more desirable method for the constriction of the transverse aorta in mice than standard open-chest transverse aortic constriction (TAC). Although transverse aortic constriction is a highly functional method for the induction of high pressure in the left ventricle, it is a more difficult and lengthy procedure due to its use of artificial ventilation with tracheal intubation. TAC is oftentimes also less survivable, as the newer method, MTAC, neither requires the cutting of the ribs and intercostal muscles nor tracheal intubation with a ventilation setup. In MTAC, as opposed to a thoracotomy to access to the chest cavity, the aortic arch is reached through a midline incision in the anterior neck. The thyroid is pulled back to reveal the sternal notch. The sternum is subsequently cut down to the second rib level, and the aortic arch is reached simply by separating the connective tissues and thymus. From there, a suture can be wrapped around the arch and tied with a spacer, and then the sternal cut and skin can be closed. MTAC is a much faster and less invasive way to induce left ventricular hypertension and enables the possibility for high-throughput studies. The success of the constriction can be verified using high-frequency trans-thoracic echocardiography, particularly color Doppler and pulsed-wave Doppler, to determine the flow velocities of the aortic arch and left and right carotid arteries, the dimension of the blood vessels, and the left ventricular function and morphology. A successful constriction will also trigger significant histopathological changes, such as cardiac muscle cell hypertrophy with interstitial and perivascular fibrosis. Here, the procedure of MTAC is described, demonstrating how the resulting flow changes in the carotid arteries can be examined with echocardiography, gross morphology, and histopathological changes in the heart.

MTAC enables the induction of significant hypertension in the left ventricle in a timely manner.
As seen in Figure 1, the preparation of the primary tools for the procedure is simple and minimal, requiring only 2 - 4 30-gauge needles to be bent and held in place with a polyurethane tube. The surgical procedure itself is also less complicated, as compared to TAC, and can be performed easily. Once the thyroid has ...

Watch this Scientific Journal Video about Minimally Invasive Transverse Aortic Constriction in Mice at JoVE.com

Minimally Invasive Transverse Aortic Constriction in Mice

Minimally invasive transverse aortic constriction (MTAC) conserves the essentials of regular transverse aortic constriction (TAC) while eliminating the use of a ventilator with tracheal intubation. It proves to be a highly desirable method for high-throughput studies on left ventricular overload, particularly in translational studies.

Minimally invasive transverse aortic constriction (MTAC) is a more desirable method for the constriction of the transverse aorta in mice than standard ...

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20.3K Views.  The University of Hong Kong. Minimally invasive transverse aortic constriction (MTAC) conserves the essentials of regular transverse aortic constriction (TAC) while eliminating the use of a ventilator with tracheal intubation. It proves to be a highly desirable method for high-throughput studies on left ventricular overload, particularly in translational studies.

Video: Minimally Invasive Transverse Aortic Constriction in Mice

In vitro Measurements of Tracheal Constriction Using Mice

Transgenic and knockout mice have been powerful tools for the investigation of the physiology and pathophysiology of airways1,2. In vitro tensometry of isolated tracheal preparations has proven to be a useful assay of airway smooth muscle (ASM) contractile response in genetically modified mice. These in vitro tracheal preparations are relatively simple, provide a robust response, and retain both functional cholinergic nerve endings and muscle responses, even after long incubations.
Tracheal tensometry also provides a functional assay to study a variety of second messenger signaling pathways that affect contraction of smooth muscle. Contraction in trachea is primarily mediated by parasympathetic, cholinergic nerves that release acetylcholine onto ASM (Figure 1). The major ASM acetylcholine receptors are muscarinic M2 and M3 which are Gi/o and Gq coupled receptors, respectively3,4,5. M3 receptors evoke contraction by coupling to Gq to activate phospholipase C, increase IP3 production and IP3-mediated calcium release from the sarcoplasmic reticulum3,6,7. M2/Gi/o signaling is believed to enhance contractions by inhibition of adenylate cyclase leading to a decrease in cAMP levels5,8,9,10. These pathways constitute the so called "pharmaco-contraction coupling" of airway smooth muscle11. In addition, cholinergic signaling through M2 receptors (and modulated by M3 signaling) involves pathways that depolarize the ASM which in turn activate L-type, voltage-dependent calcium channels (Figure 1) and calcium influx (so called "excitation-contraction coupling")4,7. More detailed reviews on signaling pathways controlling airway constriction can be found4,12. The above pathways appear to be conserved between mice and other species. However, mouse tracheas differ from other species in some signaling pathways. Most prominent is their lack of contractile response to histamine and adenosine13,14, both well-known ASM modulators in humans and other species5,15.
Here we present protocols for the isolation of murine tracheal rings and the in vitro measurement of their contractile output. Included are descriptions of the equipment configuration, trachea ring isolation and contractile measurements. Examples are given for evoking contractions indirectly using high potassium stimulation of nerves and directly by depolarization of ASM muscle to activate voltage-dependent calcium influx (1. high K+, Figure 1). In addition, methods are presented for stimulations of nerves alone using electric field stimulation (2. EFS, Figure 1), or for direct stimulation of ASM muscle using exogenous neurotransmitter applied to the bath (3. exogenous ACH, Figure 1). This flexibility and ease of preparation renders the isolated trachea ring model a robust and functional assay for a number of signaling cascades involved in airway smooth muscle contraction.

In vitro Measurements of Tracheal Constriction Using Mice

Transgenic mice have been extremely useful in ascribing physiological function to genes. As such, research in general, and functional studies of airway, in particular, have undergone a remarkable shift toward murine models. Here we provide protocols for in vitro trachea constriction studies to evaluate smooth muscle function in murine airway.

Transgenic and knockout mice have been powerful tools for the investigation of the physiology and pathophysiology of airways1,2. In vitro tensometry of ...

Ascending Aortic Constriction in Rats for Creation of Pressure Overload Cardiac Hypertrophy Model

Ascending aortic constriction is the most common and successful surgical model for creating pressure overload induced cardiac hypertrophy and heart failure. Here, we describe a detailed surgical procedure for creating pressure overload and cardiac hypertrophy in rats by constriction of the ascending aorta using a small metallic clip. After anesthesia, the trachea is intubated by inserting a cannula through a half way incision made between two cartilage rings of trachea. Then a skin incision is made at the level of the second intercostal space on the left chest wall and muscle layers are cleared to locate the ascending portion of aorta. The ascending aorta is constricted to 50&#8211;60% of its original diameter by application of a small sized titanium clip. Following aortic constriction, the second and third ribs are approximated with prolene sutures. The tracheal cannula is removed once spontaneous breathing was re-established. The animal is allowed to recover on the heating pad by gradually lowering anesthesia. The intensity of pressure overload created by constriction of the ascending aorta is determined by recording the pressure gradient using trans-thoracic two dimensional Doppler-echocardiography. Overall this protocol is useful to study the remodeling events and contractile properties of the heart during the gradual onset and progression from compensated cardiac hypertrophy to heart failure stage.

We describe a stepwise procedure for creating pressure overload and left ventricular hypertrophy in Wistar rats by constriction of the ascending aorta using a small metallic clip. This model is extensively used for studying remodeling changes during cardiac hypertrophy and for identifying and evaluating strategies for regression of such changes.

Ascending aortic constriction is the most common and successful surgical model for creating pressure overload induced cardiac hypertrophy and heart ...

Minimally Invasive Establishment of Murine Orthotopic Bladder Xenografts

Orthotopic bladder cancer xenografts are the gold standard to study molecular cellular manipulations and new therapeutic agents&#160;in vivo. Suitable cell lines are inoculated either by intravesical instillation (model of nonmuscle invasive growth) or intramural injection into the bladder wall (model of invasive growth). Both procedures are complex and highly time-consuming. Additionally, the superficial model has its shortcomings due to the lack of cell lines that are tumorigenic following instillation. Intramural injection, on the other hand, is marred by the invasiveness of the procedure and the associated morbidity for the host mouse.
With these shortcomings in mind, we modified previous methods to develop a minimally invasive approach for creating orthotopic bladder cancer xenografts. Using ultrasound guidance we have successfully performed percutaneous inoculation of the bladder cancer cell lines UM-UC1, UM-UC3 and UM-UC13 into 50 athymic nude. We have been able to demonstrate that this approach is time efficient, precise and safe. With this technique, initially a space is created under the bladder mucosa with PBS, and tumor cells are then injected into this space in a second step. Tumor growth is monitored at regular intervals with bioluminescence imaging and ultrasound. The average tumor volumes increased steadily in in all but one of our 50 mice over the study period.
In our institution, this novel approach, which allows bladder cancer xenograft inoculation in a minimally-invasive, rapid and highly precise way, has replaced the traditional model.

The established technique to inoculate primary invasive orthotopic bladder cancer xenografts requires laparotomy and mobilization of the bladder. This procedure inflicts significant morbidity on the mice, is technically challenging and time-consuming. We therefore developed a high-precision, percutaneous approach utilizing ultrasound guidance.

Orthotopic bladder cancer xenografts are the gold standard to study molecular cellular manipulations and new therapeutic agents&#160;in vivo. Suitable ...

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 ...

Biology

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 ...

Technique of Minimally Invasive Transverse Aortic Constriction in Mice for Induction of Left Ventricular Hypertrophy

Transverse aortic constriction (TAC) in mice is one of the most commonly used surgical techniques for experimental investigation of pressure overload-induced left ventricular hypertrophy (LVH) and its progression to heart failure. In the majority of the reported investigations, this procedure is performed with intubation and ventilation of the animal which renders it demanding and time-consuming and adds to the surgical burden to the animal. The aim of this protocol is to describe a simplified technique of minimally invasive TAC without intubation and ventilation of mice. Critical steps of the technique are emphasized in order to achieve low mortality and high efficiency in inducing LVH.
Male C57BL/6 mice (10-week-old, 25-30 g, n=60) were anesthetized with a single intraperitoneal injection of a mixture of ketamine and xylazine. In a spontaneously breathing animal following a 3-4 mm upper partial sternotomy, a segment of 6/0 silk suture threaded through the eye of a ligation aid was passed under the aortic arch and tied over a blunted 27-gauge needle. Sham-operated animals underwent the same surgical preparation but without aortic constriction. The efficacy of the procedure in inducing LVH is attested by a significant increase in the heart/body weight ratio. This ratio is obtained at days 3, 7, 14 and 28 after surgery (n = 6 - 10 in each group and each time point). Using our technique, LVH is observed in TAC compared to sham animals from day 7 through day 28. Operative and late (over 28 days) mortalities are both very low at 1.7%.
In conclusion, our cost-effective technique of minimally invasive TAC in mice carries very low operative and post-operative mortalities and is highly efficient in inducing LVH. It simplifies the operative procedure and reduces the strain put on the animal. It can be easily performed by following the critical steps described in this protocol.

The aim of this protocol is to describe step-by-step the technique of minimally invasive transverse aortic constriction (TAC) in mice. By elimination of intubation and ventilation which are mandatory for the commonly used standard procedure, minimally invasive TAC simplifies the operative procedure and reduces the strain put on the animal.

Transverse aortic constriction (TAC) in mice is one of the most commonly used surgical techniques for experimental investigation of pressure ...

A Closed-chest Model to Induce Transverse Aortic Constriction in Mice

Research on cardiac hypertrophy and heart failure is frequently based on pressure overload mouse models induced by TAC. The standard procedure is to perform a partial thoracotomy to visualize the transverse aortic arch. However, the surgical trauma caused by the thoracotomy in open-chest models changes the respiratory physiology as the ribs are dissected and left unattached after chest closure. To prevent this, we established a minimally invasive, closed chest approach via lateral thoracotomy. Herein we approach the aortic arch via the 2nd intercostal space without entering the chest cavities, leaving the mouse with a less traumatic injury to recover from. We perform this operation using standard laboratory settings for open chest TAC procedures with equal survival rates. Apart from maintaining physiological breathing patterns due to the closed chest approach, the mice seem to benefit by showing rapid recovery, as the less invasive technique appears to facilitate a fast healing process and to reduce immune response after trauma.

Here, we present a protocol of Transverse Aortic constriction (TAC) via a lateral thoracotomy. This technique is a minimally invasive, closed chest surgical procedure aiming to simulate pressure overload and heart failure in mice utilizing standard TAC laboratory settings.

Research on cardiac hypertrophy and heart failure is frequently based on pressure overload mouse models induced by TAC. The standard procedure is to ...

Operating Transverse Aortic Constriction with Absorbable Suture to Obtain Transient Myocardial Hypertrophy

Based on twice transverse aortic constrictions (TACs) in mice, it is proved that myocardial hypertrophic preconditioning (MHP) could attenuate cardiomyocyte hypertrophy and slow down progression to heart failure. For novices, however, the MHP model is usually quite difficult to establish because of the technical obstacles in ventilator operation, opening the chest repeatedly, and bleeding caused by debanding. To facilitate this model, to increase the surgical success rate and to reduce the incidence of bleeding, we switched to absorbable sutures for the first TAC combing with a ventilator-free technique. Using a 2-week absorbable suture, we demonstrated that this procedure could cause significant myocardial hypertrophy in 2 weeks; and 4 weeks after surgery, myocardial hypertrophy was almost completely regressed to the baseline. Using this protocol, the operators could master the MHP model easily with a lower operation mortality.

This protocol presents an improved method to obtain transient myocardial hypertrophy with absorbable suture, simulating left ventricular hypertrophy decrease after removing pressure overload. It could be valuable for the studies on myocardial hypertrophic preconditioning.

Based on twice transverse aortic constrictions (TACs) in mice, it is proved that myocardial hypertrophic preconditioning (MHP) could attenuate ...

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 ...

Transverse Aortic Arch Banding in Mouse Model: A Minimally Invasive Technique in Mice for Induction of High Pressure in the Left Ventricle

Source: Zaw, A. M. et al. <a href="https://www-jove-com.bdigitaluss.remotexs.co/video/55293" target="_blank">Minimally Invasive Transverse Aortic Constriction in Mice</a>. J. Vis. Exp. (2017)
In this video, we demonstrate an experimental protocol for minimally invasive transverse aortic constriction in mice to examine pressure overload-induced heart failure.

Source: Zaw, A. M. et al. Minimally Invasive Transverse Aortic Constriction in Mice. J. Vis. Exp. (2017)
In this video, we demonstrate an experimental ...

Minimally Invasive Transverse Aortic Constriction in Mice

Summary

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Chapters in this video

In vitro Measurements of Tracheal Constriction Using Mice

Ascending Aortic Constriction in Rats for Creation of Pressure Overload Cardiac Hypertrophy Model

Minimally Invasive Establishment of Murine Orthotopic Bladder Xenografts

Transverse Aortic Constriction in Mice

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

Technique of Minimally Invasive Transverse Aortic Constriction in Mice for Induction of Left Ventricular Hypertrophy

A Closed-chest Model to Induce Transverse Aortic Constriction in Mice

Operating Transverse Aortic Constriction with Absorbable Suture to Obtain Transient Myocardial Hypertrophy

A Modified Technique for Transverse Aortic Constriction in Mice

Transverse Aortic Arch Banding in Mouse Model: A Minimally Invasive Technique in Mice for Induction of High Pressure in the Left Ventricle