This work was supported by grants from the National Key R&#38;D Program of China (2016YFE0204700), the National Natural Science Foundation of China (82070257, 81770240), and the Research Grant of Key Laboratory of Regenerative Medicine, Ministry of Education, Jinan University (ZSYXM202004 and ZSYXM202104), China.

All the experimental protocols related to X. tropicalis were approved by the Jinan University Animal Care Committee.
1. Surgery
<ol>
	<li>Preoperative preparation: Keep ready ophthalmic scissors, ophthalmic forceps, needle forceps, absorbent balls, filter paper, and surgical sutures/needles for apex resection in the hearts of X. tropicalis. Refer to the Table of Materials for detailed information. Before use, sterilize all the surgical instruments by autoclaving, and prepare an adequate quantity of ice for future use.</li>
	<li>Anesthetize an adult X. tropicalis with tricaine by placing it&#160;in 500 mL of tricaine solution (1 mg/mL) at room temperature for 4 min19, and then put it on a surface of ice on the operating table to ensure the frog does not wake up during the operating process. 
	&#8203;CAUTION: The whole procedure requires 5-10 min; the time of anesthesia should not be too long, otherwise the X. tropicalis may not be able to wake up after the operation.</li>
	<li>Thoracotomy
	<ol>
		<li>Place the anesthetized X. tropicalis abdomen up, and cover the abdomen of the frog with gauze presoaked in distilled water to avoid the drying of the animal&#39;s skin during the operation.</li>
		<li>Gently press the chest with forceps, find the center of the chest parallel to the lower forelimb, lift the skin with ophthalmic scissors, and gently make a small incision of ~1 cm. Using ophthalmic scissors, pick up the muscle layer under the skin, and create a wound in the central chest muscle. As the heart is located in the upper position of the wound site, gently press the chest with the ophthalmic forceps to squeeze the heart out from the wound. 
		CAUTION: As the skin of X. tropicalis can produce antimicrobial peptides, it is unnecessary to employ conventional disinfection procedures on the surgical site of the X. tropicalis. Any disinfectant will damage the skin of the X. tropicalis.</li>
	</ol>
	</li>
	<li>Ventricular apex resection
	<ol>
		<li>Gently clamp the pericardium with forceps, and gently break it using ophthalmic scissors near the apex of the heart. Wait for the pericardium to come off due to systolic blood pumping (Figure 1A, B).</li>
		<li>Hold the tip of the heart with forceps in the non-dominant hand, and lift the heart slightly according to the cardiac contraction rhythm. When the heart contracts to recirculate blood through the blood vessels, quickly cut off the apex of the heart (~14% of the ventricle) (Figure 1C).</li>
		<li>To ensure the amount of apex resection is approximately 14% of the whole heart, analyze the heart weight (HW) and surface area with or without resection20. Place the heart into the chest using forceps and an absorbent ball. 
		NOTE: Do not press the heart directly with the forceps; otherwise, other parts of the heart will be punctured.</li>
	</ol>
	</li>
	<li>Suture the skin with a 4-0 non-absorbent non-silk surgical thread suture (Figure 1D). Be careful to avoid suturing into the muscle layer to prevent postoperative mortality. Wait for the skin wound to naturally heal within 1 week following surgery.</li>
	<li>In the sham operation group, perform the thoracotomy, open the pericardium, and suture, without performing the apex resection.</li>
</ol>
2. Surgical recovery
<ol>
	<li>Place the postoperative X. tropicalis with its abdomen facing up in a Petri dish containing a small quantity of deionized water (do not completely flood the animal). Wait for the X. tropicalis to wake up within ~10 min.</li>
	<li>Upon regaining consciousness, observe the animal&#39;s mobility and activity, as well as the wound suture during activity. Transfer the frogs that have regained their balance to a container filled with pure water for cultivation. Replace the water with pure water every day to avoid wound infection. 
	&#8203;NOTE: With these measures, the survival rate could reach ~90%. A prolonged time of anesthesia and excessive bleeding during surgery both lead to death, which typically occurs on the day of surgery.</li>
</ol>
3. Detection of the repair condition after cardiac injury
<ol>
	<li>Collect the hearts of X. tropicalis at multiple time points after surgery.
	<ol>
		<li>After anesthetizing the X. tropicalis with tricaine, open the abdomen, and use forceps to remove the other internal organs and tissues to find the location of the heart. 
		NOTE: Due to the apex resection, the heart is likely to develop alongside other tissues and organs during the repair process. Sometimes, it sticks to the muscle wall and is not easy to separate, so it needs to be handled carefully during collection.</li>
		<li>After finding the heart, use forceps to gently tear the other organs from the heart. Gently peel away the other tissues surrounding the heart to expose the heart. Use forceps to gently lift the heart, and cut it out using scissors. Place the heart immediately in PBS to remove any remaining blood, and photograph it with a stereoscope for documentation (Figure 2).</li>
	</ol>
	</li>
	<li>Gradient dehydration
	<ol>
		<li>Blot the hearts with filter paper to dry the excess PBS residues, and place them in a 24-well cell culture dish. Use 1-2 ml of 4% paraformaldehyde to fix the heart tissues overnight. The following day, perform ethanol dehydration. First, use 70% ethanol overnight, followed by 80% ethanol, 90% ethanol, and 100% ethanol for gradient dehydration (1 h each time). Repeat the use of 100% ethanol three times.</li>
	</ol>
	</li>
	<li>Paraffin embedding
	<ol>
		<li>Treat the dehydrated heart tissue with xylene for 6-8 min. Place the xylene-treated tissue in a glass container filled with paraffin wax at 65 &#176;C for 2-3 h. 
		&#8203;NOTE: It is essential to avoid air bubbles as they affect the section during the embedding process.</li>
	</ol>
	</li>
	<li>Freeze the embedded tissue at &#8722;20 &#176;C for 1 h, and section it.</li>
	<li>After sectioning the heart, perform standard hematoxylin and eosin (H&#38;E) and Masson&#39;s trichrome staining techniques on the sections11.</li>
</ol>

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P., Virmani, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pathophysiology+of+acute+myocardial+infarction.">Pathophysiology of acute myocardial infarction.</a> Medical Clinics of North America. 91 (4), 553-572 (2007).</li><li>Sessions, S. K., Bryant, S. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evidence+that+regenerative+ability+is+an+intrinsic+property+of+limb+cells+in+Xenopus.">Evidence that regenerative ability is an intrinsic property of limb cells in Xenopus.</a> Journal of Experimental Zoology. 247 (1), 39-44 (1988).</li><li>Laflamme, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heart+regeneration.">Heart regeneration.</a> Nature. 473 (7347), 326-335 (2011).</li><li>Mahmoud, A. 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R., 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=Transient+regenerative+potential+of+the+neonatal+mouse+heart.">Transient regenerative potential of the neonatal mouse heart.</a> Science. 331 (6020), 1078-1080 (2011).</li><li>Porrello, E. R., 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=Regulation+of+neonatal+and+adult+mammalian+heart+regeneration+by+the+miR-15+family.">Regulation of neonatal and adult mammalian heart regeneration by the miR-15 family.</a> Proceedings of the National Academy of Sciences of the United States of America. 110 (1), 187-192 (2013).</li><li>Poss, K. D., Wilson, L. G., Keating, M. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heart+regeneration+in+zebrafish.">Heart regeneration in zebrafish.</a> Science. 298 (5601), 2188-2190 (2002).</li><li>Liao, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heart+regeneration+in+adult+Xenopus+tropicalis+after+apical+resection.">Heart regeneration in adult Xenopus tropicalis after apical resection.</a> Cell &amp; Bioscience. 7, 70 (2017).</li><li>Marshall, L. 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=Stage-dependent+cardiac+regeneration+in+Xenopus+is+regulated+by+thyroid+hormone+availability.">Stage-dependent cardiac regeneration in Xenopus is regulated by thyroid hormone availability.</a> Proceedings of the National Academy of Sciences of the United States of America. 116 (9), 3614-3623 (2019).</li><li>Witman, N., Murtuza, B., Davis, B., Arner, A., Morrison, J. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recapitulation+of+developmental+cardiogenesis+governs+the+morphological+and+functional+regeneration+of+adult+newt+hearts+following+injury.">Recapitulation of developmental cardiogenesis governs the morphological and functional regeneration of adult newt hearts following injury.</a> Developmental Biology. 354 (1), 67-76 (2011).</li><li>Cano-Martinez, 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=Functional+and+structural+regeneration+in+the+axolotl+heart+(Ambystoma+mexicanum)+after+partial+ventricular+amputation.">Functional and structural regeneration in the axolotl heart (Ambystoma mexicanum) after partial ventricular amputation.</a> Archivos de Cardiolog&#237;a de M&#233;xico. 80 (2), 79-86 (2010).</li><li>Kragl, 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=Cells+keep+a+memory+of+their+tissue+origin+during+axolotl+limb+regeneration.">Cells keep a memory of their tissue origin during axolotl limb regeneration.</a> Nature. 460 (7251), 60-65 (2009).</li><li>Oberpriller, J. 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The authors have no conflicts of interest to declare.

Apical resection, which involves the surgical amputation of the apex of the heart, has been described in zebrafish and mice6,18; however, this has not been described in X. tropicalis. This report describes a credible model of cardiac injury and demonstrates that the heart of adult X. tropicalis can fully regenerate after apical resection without scarring. However, some shortcomings need to be improved, and certain details need attention. 
<p...

Heart failure has been a leading cause of mortality worldwide in recent years. Since 2000, the number of deaths due to heart failure has been increasing over time. More than 9 million people died from cardiomyopathy in 2019, which accounted for 16% of the total number of mortalities globally1. Due to the loss of the regenerative capacity of the heart in adult mammals, in some cases, there are not enough cardiomyocytes to maintain the contraction functions in the heart, which affects heart function and contributes to abnormal ventricular remodeling and heart failure2,3,4. Indeed, in mammals, the heart has the poorest regenerative capacity compared to the other organs, such as the liver, lungs, intestines, bladder, bone, and skin. As the aging of the world&#39;s population becomes a global megatrend, the challenges we face with heart disease will intensify5.
Elucidating the mechanisms of cardiac regeneration may have significant implications for therapies for ischemic heart disease. Reports have revealed that the hearts of neonatal mice have a regenerative capacity after apex resection6. Nevertheless, this regenerative capacity is lost after 7 days of age7. Studies have demonstrated that adult mammalian hearts are unable to regenerate because their capacity for cardiomyocyte proliferation has diminished8,9. However, the hearts of lower vertebrates possess a powerful regenerative capacity after injury. For instance, zebrafish10, X. tropicalis11, Xenopus laevis12, newt13, and axolotl14 are capable of complete regeneration after apex resection. Additionally, the other parts of the bodies of some lower vertebrates can also undergo complete regeneration, such as the limbs of newts and the tails, lenses, and arms of tropical clawed frogs4,15,16.
Establishing cardiac injury models is the first step to elucidating the mechanisms underlying cardiac regeneration and has great significance in regenerative research. Researchers have developed various methods to build cardiac injury models, including stabbing, contusing, genetic ablation, cryoinjury, and infarction5,6.
Cryoinjury, myocardial infarction (MI), and apex resection are widely used for inducing cardiac injury, and the type of injury may have substantial effects on the following regeneration of cardiomyocytes6. Depending on the surgical technique, the heart&#39;s response to regeneration could vary. Cryoinjury causes massive cell death and produces fibrotic scars in the hearts of zebrafish17, thus creating a model that resembles mammalian infarction. Apical resection is performed by cutting away a part of the ventricular tissues, which has been done in zebrafish10 and X. tropicalis11, without causing permanent scars. This study performed apical resection, which is a simpler operation and requires fewer surgical instruments than cryoinjury. Using lineage-tracing analysis, a previous study demonstrated that cardiac regeneration is related to the proliferation of cardiomyocytes that pre-exist in the hearts of the mouse6 and zebrafish18, but no reports exist for amphibians. Hence, the model of apex resection in X. tropicalis plays an important role in elucidating the mechanisms underlying regenerative responses.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Acetic acid</td>
			<td>GHTECH</td>
			<td>64-19-7-500ml</td>
			<td></td>
		</tr>
		<tr>
			<td>Acid Alcohol Fast Differentiation Solution</td>
			<td>Beyotime</td>
			<td>C0163M</td>
			<td></td>
		</tr>
		<tr>
			<td>Acid Fuchsin</td>
			<td>aladdin</td>
			<td>A104916</td>
			<td></td>
		</tr>
		<tr>
			<td>Alcohol Soluble Eosin Y Stainin Solution</td>
			<td>Servicebio</td>
			<td>G1001-500ML</td>
			<td></td>
		</tr>
		<tr>
			<td>BioReagent</td>
			<td>Beyotime</td>
			<td>ST2600-100g</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol absolute</td>
			<td>Guangzhou Chemical Reagent Factory</td>
			<td>HB15-GR-0.5L</td>
			<td></td>
		</tr>
		<tr>
			<td>Hematoxylin Stain Solution</td>
			<td>Servicebio</td>
			<td>G1004-500ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Neutral balsam</td>
			<td>Solarbio</td>
			<td>G8590</td>
			<td></td>
		</tr>
		<tr>
			<td>Operating Scissors</td>
			<td>Prosperich</td>
			<td>HC-JZ-YK-Z-10cm</td>
			<td></td>
		</tr>
		<tr>
			<td>Paraffins</td>
			<td>Leica</td>
			<td>39601095</td>
			<td></td>
		</tr>
		<tr>
			<td>Para-formaldehyde Fixative</td>
			<td>Servicebio</td>
			<td>G1101-500ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate Buffered Saline (PBS) powder</td>
			<td>Servicebio</td>
			<td>G0002-2L</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphomolybdic&#160;acid&#160;hydrate</td>
			<td>Macklin</td>
			<td>P815551</td>
			<td></td>
		</tr>
		<tr>
			<td>Stereo microscope</td>
			<td>Leica</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>surgical forceps</td>
			<td>ChangZhou</td>
			<td>zfq-11-btjw</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical Suture</td>
			<td>HUAYON</td>
			<td>18-5140</td>
			<td></td>
		</tr>
		<tr>
			<td>Tricaine</td>
			<td>Macklin</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Xylene</td>
			<td>Guangzhou Chemical Reagent Factory</td>
			<td>IC02-AR-0.5L</td>
			<td></td>
		</tr>
	</tbody>
</table>

an apical resection model in the adult xenopus tropicalis heart

It is known that in adult mammals, the heart has lost its regenerative capacity, making heart failure one of the leading causes of death worldwide. Previous research has demonstrated the regenerative ability of the heart of the adult Xenopus tropicalis, an anuran amphibian with a diploid genome and a close evolutionary relationship with mammals. Additionally, studies have shown that following ventricular apex resection, the heart can regenerate without scarring in X. tropicalis. Consequently, these previous results suggest that X. tropicalis is an appropriate alternative vertebrate model for the study of adult heart regeneration. A surgical model of cardiac regeneration in the adult X. tropicalis is presented herein. Briefly, the frogs were anesthetized and fixed; then, a small incision was made with iridectomy scissors, penetrating the skin and pericardium. Gentle pressure was applied to the ventricle, and the apex of the ventricle was then cut out with scissors. Cardiac injury and regeneration were confirmed by histology at 7-30 days post resection (dpr). This protocol established an apical resection model in adult X. tropicalis, which&#160;can be employed to elucidate the mechanisms of adult heart regeneration.

The hearts were collected at 0 dpr, 7 dpr, 14 dpr, and 30 dpr. The morphological analysis revealed that the blood clot caused by the heart injury disappeared at 30 dpr (Figure 2). At the same time, the appearance of the hearts at 30 dpr in the resection group was similar to that of the hearts in the sham operation group; there were no obvious wounds (Figure 2). After apical resection, a blood clot formed and sealed the wound in the ventricle, as observed by H&#3...

Watch this Scientific Journal Video about An Apical Resection Model in the Adult Xenopus tropicalis Heart at JoVE.com

An Apical Resection Model in the Adult Xenopus tropicalis Heart

Xenopus tropicalis is an ideal model for regenerative research as many of its organs possess a remarkable regenerative capacity. Here, we present a method for constructing a heart injury model in X. tropicalis via apex resection.

An Apical Resection Model in the Adult Xenopus tropicalis Heart

It is known that in adult mammals, the heart has lost its regenerative capacity, making heart failure one of the leading causes of death worldwide. ...

an-apical-resection-model-in-the-adult-xenopus-tropicalis-heart

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1.3K Views.  Jinan University. Xenopus tropicalis is an ideal model for regenerative research as many of its organs possess a remarkable regenerative capacity. Here, we present a method for constructing a heart injury model in X. tropicalis via apex resection. 

Video: An Apical Resection Model in the Adult Xenopus tropicalis Heart

Implantation of Total Artificial Heart in Congenital Heart Disease

In patients with end-stage heart failure (HF), a total artificial heart (TAH) may be implanted as a bridge to cardiac transplant. However, in congenital heart disease (CHD), the malformed heart presents a challenge to TAH implantation. 
In the case presented here, a 17 year-old patient with congenital transposition of the great arteries (CCTGA) experienced progressively worsening HF due to his congenital condition. He was hospitalized multiple times and received an implantable cardioverter defibrillator (ICD). However, his condition soon deteriorated to end-stage HF with multisystem organ failure. 
Due to the patient's grave clinical condition and the presence of complex cardiac lesions, the decision was made to proceed with a TAH. The abnormal arrangement of the patient's ventricles and great arteries required modifications to the TAH during implantation.
With the TAH in place, the patient was able to return home and regain strength and physical well-being while awaiting a donor heart. He was successfully bridged to heart transplantation 5 months after receiving the device. This report highlights the TAH is feasible even in patients with structurally abnormal hearts, with technical modification.

This is a case report of a patient with congenitally corrected transposition of the great arteries (CCTGA) who received a total artificial heart (TAH) as a bridge to heart transplant. The TAH was successfully implanted with modifications to accommodate the patient's congenitally malformed heart.

In patients with end-stage heart failure (HF), a total artificial heart (TAH) may be implanted as a bridge to cardiac transplant. However, in congenital ...

Apical Resection Mouse Model to Study Early Mammalian Heart Regeneration

Cardiovascular disease plagues the whole world due to intensive lifestyle changes. Heart regeneration holds great promise for repairing and restoring cardiomyocytes lost due to injury and disease. In contrast to the robust cardiac regeneration of certain lower vertebrates, adult mammalian hearts typically show minimal capacity for heart regeneration and repair. However, recent studies have sparked considerable scientific interest with the finding that, between postnatal day 1 to 7 (P1 to P7), the neonatal mouse heart retains significant regenerative potential after apical resection (i.e., surgical amputation and exposure of left ventricular apex). One major controversy over this finding might be due to the diverse surgery-related procedures used in efforts to replicate or expand upon this important finding. These instructions dynamically present the materials and methodology for apical resection in a mouse model. The salient steps of this rodent survival surgery involve hypothermia anesthesia, thoracotomy, surgical amputation of heart ventricular apex, and suture and recovery of mice. The approach described could expand the application of the apical resection mouse model for cardiovascular research.

A step-by-step video protocol of apical resection is demonstrated in this study. Apical resection is a recently highlighted surgical approach in mammalian heart regeneration research. This study may promote the application of apical resection as a standard methodology in research into the mechanism underlying heart regeneration.

Cardiovascular disease plagues the whole world due to intensive lifestyle changes. Heart regeneration holds great promise for repairing and restoring ...

The Inverted Heart Model for Interstitial Transudate Collection from the Isolated Rat Heart

The present protocol describes a unique approach that enables the collection of cardiac transudate (CT) from the isolated, saline-perfused rat heart. After isolation and retrograde perfusion of the heart according to the Langendorff technique, the heart is inverted into an upside-down position and is mechanically stabilized by a balloon catheter inserted into the left ventricle. Then, a thin latex cap &#8211; previously cast to match the average size of the rat heart &#8211; is placed over the epicardial surface. The outlet of the latex cap is connected to silicon tubing, with the distal opening 10 cm below the base level of the heart, creating slight suction. CT continuously produced on the epicardial surface is collected in ice-cooled vials for further analysis. The rate of CT formation ranged from 17 to 147 &#181;L/min (n = 14) in control and infarcted hearts, which represents 0.1-1% of the coronary venous effluent perfusate. Proteomic analysis and high performance liquid chromatography (HPLC) revealed that the collected CT contains a wide spectrum of proteins and purinergic metabolites.

This protocol describes a method to collect cardiac interstitial fluid from the isolated, perfused rat heart. To physically separate interstitial transudate from coronary venous effluent perfusate, the Langendorff perfused heart is inverted, and the transudate (interstitial fluid) formed on the cardiac surface is collected using a soft latex cap.

The present protocol describes a unique approach that enables the collection of cardiac transudate (CT) from the isolated, saline-perfused rat heart. ...

A Chronic Cardiac Ischemia Model in Swine Using an Ameroid Constrictor

Cardiovascular disease remains the number one cause of mortality in the United States. There are numerous approaches to treating these diseases, but regardless of the approach, an in vivo model is needed to test each treatment. The pig is one of the most used large animal models for cardiovascular disease. Its heart is very similar in anatomy and function to that of a human. The ameroid placement technique creates an ischemic area of the heart, which has many useful applications in studying myocardial infarction. This model has been used for surgical research, pharmaceutical studies, imaging techniques, and cell therapies.
There are several ways of inducing an ischemic area in the heart. Each has its advantages and disadvantages, but the placement of an ameroid constrictor remains the most widely used technique. The main advantages to using the ameroid are its prevalence in existing research, its availability in various sizes to accommodate the anatomy and size of the vessel to be constricted, the surgery is a relatively simple procedure, and the post-operative monitoring is minimal, since there are no external devices to maintain. This paper provides a detailed overview of the proper technique for the placement of the ameroid constrictor.

The purpose of this protocol is to demonstrate the placement of a delayed constricting device (an ameroid constrictor) around a coronary artery in a swine model. This device creates an ischemic area of the heart that is useful for studying new diagnostic imaging techniques and new methods of treatment.

Cardiovascular disease remains the number one cause of mortality in the United States. There are numerous approaches to treating these diseases, but ...

Isometric Contractility Measurement of the Mouse Mesenteric Artery Using Wire Myography

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and drugs. It is widely used in many studies on the physiological functions of vascular smooth muscle, the pathogenesis of vascular diseases such as hypertension, and the development of smooth muscle relaxant drugs. The mouse is a widely used model animal with a large pool of disease models and genetically modified strains. We introduced this method to measure the isometric contraction of mouse mesenteric artery in detail. A 1.4-mm segment of mouse mesenteric resistance artery was isolated and mounted on a myograph chamber by passing two steel wires through its lumen. After equilibration and normalization steps, the vessel segment was potentiated by a high-K+ solution twice prior to the contraction assay. As an example of the application of this method in drug development, we measured the relaxant effect of a novel natural substance, neoliensinine, isolated from a Chinese herb, embryos of the lotus seed (Nelumbo nucifera Gaertn.) on mouse mesenteric arteries. The vessel segments mounted on the myograph chamber were stimulated with a high-K+ solution. When the force tension reached a stable sustained phase, cumulative doses of neoliensinine were added to the chamber. We found that neoliensinine had a dose-dependent relaxant effect on smooth muscle contraction, thus suggesting that it bears potential activity against hypertension. In addition, as the vessel segment can survive at least 4 hours after mounting and maintain contractility induced by the high-K+ solution for many times, we suggest that the wire myograph system may be used for the time-consuming process of drug screening.

The wire myograph technique is used to investigate vascular smooth muscle functions and screen new drugs. We report a detailed protocol for measuring the isometric contractility of the mouse mesenteric artery and for screening new relaxants of vascular smooth muscle.

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and ...

A Cryoinjury Model to Study Myocardial Infarction in the Mouse

The use of animal models is essential for developing new therapeutic strategies for acute coronary syndrome and its complications. In this article, we demonstrate a murine cryoinjury infarct model that generates precise infarct sizes with high reproducibility and replicability. In brief, after intubation and sternotomy of the animal, the heart is lifted from the thorax. The probe of a handheld liquid nitrogen delivery system is applied onto the myocardial wall to induce cryoinjury. Impaired ventricular function and electrical conduction can be monitored with echocardiography or optical mapping. Transmural myocardial remodeling of the infarcted area is characterized by collagen deposition and loss of cardiomyocytes. Compared to other models (e.g., LAD-ligation), this model utilizes a handheld liquid nitrogen delivery system to generate more uniform infarct sizes.

This article demonstrates a model to study cardiac remodeling after myocardial cryoinjury in mice.

The use of animal models is essential for developing new therapeutic strategies for acute coronary syndrome and its complications. In this article, we ...

An Image Guided Transapical Mitral Valve Leaflet Puncture Model of Controlled Volume Overload from Mitral Regurgitation in the Rat

Mitral regurgitation (MR) is a widely prevalent heart valve lesion, which causes cardiac remodeling and leads to congestive heart failure. Though the risks of uncorrected MR and its poor prognosis are known, the longitudinal changes in cardiac function, structure and remodeling are incompletely understood. This knowledge gap has limited our understanding of the optimal timing for MR correction, and the benefit that early versus late MR correction may have on the left ventricle. To investigate the molecular mechanisms that underlie left ventricular remodeling in the setting of MR, animal models are necessary. Traditionally, the aorto-caval fistula model has been used to induce volume overload, which differs from clinically relevant lesions such as MR. MR represents a low-pressure volume overload hemodynamic stressor, which requires animal models that mimic this condition. Herein, we describe a rodent model of severe MR in which the anterior leaflet of the rat mitral valve is perforated with a 23G needle, in a beating heart, with echocardiographic image guidance. The severity of MR is assessed and confirmed with echocardiography, and the reproducibility of the model is reported.&#160;&#160;

A rodent model of left heart volume overload from mitral regurgitation is reported. Mitral regurgitation of controlled severity is induced by advancing a needle of defined dimensions into the anterior leaflet of the mitral valve, in a beating heart, with ultrasound guidance.&#160;

Mitral regurgitation (MR) is a widely prevalent heart valve lesion, which causes cardiac remodeling and leads to congestive heart failure. Though the ...

Blood Circuit Reconstruction in an Abdominal Mouse Heart Transplantation Model

The surgical technique of heterotopic abdominal heart transplantation in mice is a standard model for research in transplantation immunology. Here, the established technique for a modified blood circuit reconstruction in a heterotopic abdominal heart transplantation model is presented. This method uses the intrathoracic inferior vena cava (IIVC) instead of the pulmonary artery of the donor heart for the anastomosis to the inferior vena cava of the recipient. It is facilitating and improving success rates for abdominal heart transplantation in mice.

A novel technique for blood circuit reconstruction in a heterotopic abdominal mouse heart transplantation model is demonstrated.

The surgical technique of heterotopic abdominal heart transplantation in mice is a standard model for research in transplantation immunology. Here, the ...

An In Vivo Mouse Model of Total Intravenous Anesthesia During Cancer Resection Surgery

Anesthesia is a routine component of cancer care that is used for diagnostic and therapeutic procedures. The anesthetic technique has recently been implicated in impacting long-term cancer outcomes, possibly through modulation of adrenergic-inflammatory responses that impact cancer cell behavior and immune cell function. Emerging evidence suggests that propofol-based total intravenous anesthesia (TIVA) may be beneficial for long-term cancer outcomes when compared to inhaled volatile anesthesia. However, the available clinical findings are inconsistent. Preclinical studies that identify the underlying mechanisms involved are critically needed to guide the design of clinical studies that will expedite insight. Most preclinical models of anesthesia have been extrapolated from the use of anesthesia in in vivo research and are not optimally designed to study the impact of anesthesia itself as the primary endpoint. This paper describes a method for delivering propofol-TIVA anesthesia in a mouse model of breast cancer resection that replicates key aspects of clinical delivery in cancer patients. The model can be used to study mechanisms of action of anesthesia on cancer outcomes in diverse cancer types and can be extrapolated to other non-cancer areas of preclinical anesthesia research.

An In Vivo Mouse Model of Total Intravenous Anesthesia During Cancer Resection Surgery

This paper describes a method for modeling total intravenous anesthesia (TIVA) during cancer resection surgery in mice. The goal is to replicate key features of anesthesia delivery to patients with cancer. The method allows investigation of how anesthetic technique affects cancer recurrence after resection surgery.

Anesthesia is a routine component of cancer care that is used for diagnostic and therapeutic procedures. The anesthetic technique has recently been ...

Transcatheter Pulmonary Valve Replacement from Autologous Pericardium with a Self-Expandable Nitinol Stent in an Adult Sheep Model

Transcatheter pulmonary valve replacement has been established as a viable alternative approach for patients suffering from right ventricular outflow tract or bioprosthetic valve dysfunction, with excellent early and late clinical outcomes. However, clinical challenges such as stented heart valve deterioration, coronary occlusion, endocarditis, and other complications must be addressed for lifetime application, particularly in pediatric patients. To facilitate the development of a lifelong solution for patients, transcatheter autologous pulmonary valve replacement was performed in an adult sheep model. The autologous pericardium was harvested from the sheep via left anterolateral minithoracotomy under general anesthesia with ventilation. The pericardium was placed on a 3D shaping heart valve model for non-toxic cross-linking for 2 days and 21 h. Intracardiac echocardiography (ICE) and angiography were performed to assess the position, morphology, function, and dimensions of the native pulmonary valve (NPV). After trimming, the crosslinked pericardium was sewn onto a self-expandable Nitinol stent and crimped into a self-designed delivery system. The autologous pulmonary valve (APV) was implanted at the NPV position via left jugular vein catheterization. ICE and angiography were repeated to evaluate the position, morphology, function, and dimensions of the APV. An APV was successfully implanted in&#160;sheep J. In this paper, sheep J was selected to obtain representative results. A 30 mm APV with a Nitinol stent was accurately implanted at the NPV position without any significant hemodynamic change. There was no paravalvular leak, no new pulmonary valve insufficiency, or stented pulmonary valve migration. This study demonstrated the feasibility and safety, in a long-time follow-up, of developing an APV for implantation at the NPV position with a self-expandable Nitinol stent via jugular vein catheterization in an adult sheep model.

This study demonstrates the feasibility and safety of developing an autologous pulmonary valve for implantation at the native pulmonary valve position by using a self-expandable Nitinol stent in an adult sheep model. This is a step toward developing transcatheter pulmonary valve replacement for patients with right ventricular outflow tract dysfunction.

Transcatheter pulmonary valve replacement has been established as a viable alternative approach for patients suffering from right ventricular outflow ...