Name: a modified technique for transverse aortic constriction in mice
Uploaded: 2022-08-18T15:00:00
Description: Watch this Scientific Journal Video about A Modified Technique for Transverse Aortic Constriction in Mice at JoVE.com

This work is funded by the National Natural Science Foundation of China (NSFC 81822002). We thank all the members who took part in this work.

The current protocol is approved by the ethics committee of Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China. This procedure is performed on male adult C57/BL6 mice (&#62;10 weeks of age). All surgical instruments were sterilized by autoclaving before the operation.
1. Preparation of surgical instrument
<ol>
	<li>Prepare a 5 mL syringe and pinch off the tip of the needle with a needle holder to blunt it.&#160;</li>
	<li>Pre...

<ol>
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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=ESC+Guidelines+for+the+diagnosis+and+treatment+of+acute+and+chronic+heart+failure.">ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure.</a> European Heart Journal. 42 (36), 3599 (2021).</li><li>Lv, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Induction+of+myocardial+infarction+and+myocardial+ischemia-reperfusion+injury+in+mice.">Induction of myocardial infarction and myocardial ischemia-reperfusion injury in mice.</a> Journal of Visualized Experiments. 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O., 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+novel+method+for+high+precision+aortic+constriction+that+allows+for+generation+of+specific+cardiac+phenotypes+in+mice.">A novel method for high precision aortic constriction that allows for generation of specific cardiac phenotypes in mice.</a> Cardiovascular Research. 114 (12), 1680-1690 (2018).</li><li>Rockman, H. A., Wachhorst, S. P., Mao, L., Ross, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ANG+II+receptor+blockade+prevents+ventricular+hypertrophy+and+ANF+gene+expression+with+pressure+overload+in+mice.">ANG II receptor blockade prevents ventricular hypertrophy and ANF gene expression with pressure overload in mice.</a> The American Journal of Physiology. 266, 2468-2475 (1994).</li><li>Eichhorn, 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=A+closed-chest+model+to+induce+transverse+aortic+constriction+in+mice.">A closed-chest model to induce transverse aortic constriction in mice.</a> Journal of Visualized Experiments. (134), e57397 (2018).</li><li>Tavakoli, R., Nemska, S., Jamshidi, P., Gassmann, M., Frossard, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Technique+of+minimally+invasive+transverse+aortic+constriction+in+mice+for+induction+of+left+ventricular+hypertrophy.">Technique of minimally invasive transverse aortic constriction in mice for induction of left ventricular hypertrophy.</a> Journal of Visualized Experiments. (127), e56231 (2017).</li><li>Lang, R. 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=Recommendations+for+cardiac+chamber+quantification+by+echocardiography+in+adults:+an+update+from+the+American+Society+of+Echocardiography+and+the+European+Association+of+Cardiovascular+Imaging.">Recommendations for cardiac chamber quantification by echocardiography in adults: an update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging.</a> Journal of the American Society of Echocardiography. 28 (1), 1-39 (2015).</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> Journal of Visualized Experiments. (112), e54101 (2016).</li><li>Wang, 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=ATF4+protects+the+heart+from+failure+by+antagonizing+oxidative+stress.">ATF4 protects the heart from failure by antagonizing oxidative stress.</a> Circulation Research. 131 (1), 91-105 (2022).</li><li>Li, 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=GCN5-mediated+regulation+of+pathological+cardiac+hypertrophy+via+activation+of+the+TAK1-JNK/p38+signaling+pathway.">GCN5-mediated regulation of pathological cardiac hypertrophy via activation of the TAK1-JNK/p38 signaling pathway.</a> Cell Death &amp; Disease. 13 (4), 421 (2022).</li><li>Syed, A. 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=Up-regulation+of+Nrf2/HO-1+and+inhibition+of+TGF-beta1/Smad2/3+signaling+axis+by+daphnetin+alleviates+transverse+aortic+constriction-induced+cardiac+remodeling+in+mice.">Up-regulation of Nrf2/HO-1 and inhibition of TGF-beta1/Smad2/3 signaling axis by daphnetin alleviates transverse aortic constriction-induced cardiac remodeling in mice.</a> Free Radical Biology and Medicine. 186, 17-30 (2022).</li><li>Zaw, A. M., Williams, C. M., Law, H. K., Chow, B. K. <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+transverse+aortic+constriction+in+mice.">Minimally invasive transverse aortic constriction in mice.</a> Journal of Visualized Experiments. (121), e55293 (2017).</li><li>Lao, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Operating+transverse+aortic+constriction+with+absorbable+suture+to+obtain+transient+myocardial+hypertrophy.">Operating transverse aortic constriction with absorbable suture to obtain transient myocardial hypertrophy.</a> Journal of Visualized Experiments. (163), e61686 (2020).</li><li>Veldhuizen, R. A., Slutsky, A. S., Joseph, M., McCaig, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+mechanical+ventilation+of+isolated+mouse+lungs+on+surfactant+and+inflammatory+cytokines.">Effects of mechanical ventilation of isolated mouse lungs on surfactant and inflammatory cytokines.</a> European Respiratory Journal. 17 (3), 488-494 (2001).</li><li>Withaar, C., Lam, C. S. P., Schiattarella, G. G., de Boer, R. 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The induction of sustained pressure overload can gradually cause cardiac hypertrophy and heart failure. This model has been used in numerous laboratories around the world14,15,16. The protocol provided an improved TAC method that does not need microsurgical skills or mechanical ventilation.
The most important step in this protocol is passing silk suture under the aortic arch. When the snare has hooked...

Heart failure is a complex clinical symptom that results from impaired structure and function of ventricular filling or ejecting blood1. The disease stage is mainly defined via the New York Heart Association function classification based on the severity of symptoms and physical activity2. For those patients with an ejection fraction of over 50%, structural and/or functional abnormalities raised natriuretic peptides to support the diagnosis of heart failure with preserved ejection fraction (HFpEF)2. Ischemic heart disease is a leading cause among multiple etiologies of heart failure. Thus, the myocardial infarction model (such as permanent coronary ligation) is often used to study pathophysiology after cardiac hypoperfusion or ischemia-reperfusion injury3,4. Besides acute myocardial injury, other risk factors such as hypertension, diabetes, obesity, and a family history of cardiomyopathy also contribute to the development of heart failure. After patients pass Stage A (at risk for heart failure) and enter Stage B (pre-heart failure), structural modification occurs1. For example, hypertensive patients first go through adaptive left ventricle hypertrophy, and then gradually develop into maladaptive cardiac hypertrophy and transit to heart failure through pathological remodeling5.
As the terminal stage of various cardiovascular diseases, chronic heart failure has been studied for decades6. Multiple mouse models have been widely used in heart failure research, including drug infusion (angiotensin II), metabolic disorders (diabetes or high caloric diet), and aortic constriction7. Among these models, angiotensin II perfusion is accompanied by various organ side effects, such as kidney7. Inducing metabolic disorders usually require a rather long period of time. Ascending aortic constriction has been considered to have limited relevance to human disease7.
TAC is a reliable model that increases afterload and induces cardiac hypertrophy as well as heart failure8. Open-chest TAC model was first described by Rockman et al. and was used in numerous laboratories around the world9. However, this classical TAC procedure causes a rather large trauma to mice and changes their normal behavior, which may take a long recovery time and disturb further treatment10. Other modified closed-chest TAC procedures did reduce some invasive steps but required microsurgical skills or mechanical ventilation10,11.
The present protocol details a step-by-step method with a minimally invasive approach to the aortic arch using a self-made retractor via a 3 mm midline incision of the upper edge of the sternum. This model does not need microsurgical skill, mechanical ventilation, or cutting through the ribs, thereby providing a rapid, surgical trauma-limited, uncomplicated, inexpensive way to perform TAC surgery.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>4-0 nonabsorbable suture</td>
			<td>Jinhuan</td>
			<td>HM403</td>
			<td>Used for suturing the skin</td>
		</tr>
		<tr>
			<td>5 mL syringe</td>
			<td>Haifuda Technology Co., Ltd.</td>
			<td>BD-309628</td>
			<td>Used for making snare containing retractor</td>
		</tr>
		<tr>
			<td>7-0 nonabsorbable suture</td>
			<td>Jinhuan</td>
			<td>HM701</td>
			<td>Used for aorta ligation</td>
		</tr>
		<tr>
			<td>Animal temperature monitor</td>
			<td>Kaerwen</td>
			<td>FT3400</td>
			<td>Used for monitoring body temperature</td>
		</tr>
		<tr>
			<td>Buprenorphine&#160;</td>
			<td>Sigma</td>
			<td>B-044</td>
			<td>Used for post-surgical pain treatment</td>
		</tr>
		<tr>
			<td>Depilatory cream&#160;</td>
			<td>Veet</td>
			<td>N/A</td>
			<td>Used for remove body hair from the surgical area</td>
		</tr>
		<tr>
			<td>Heating Pad</td>
			<td>Xiaochuangxin</td>
			<td>N/A</td>
			<td>Used for maintaining body temperature</td>
		</tr>
		<tr>
			<td>Ibuprofen</td>
			<td>MCE</td>
			<td>HY-78131</td>
			<td>Used for post-surgical pain treatment</td>
		</tr>
		<tr>
			<td>Iron wire (0.5 mm)</td>
			<td>Qing Yuan</td>
			<td>Iron wire #26</td>
			<td>Used for making snare containing retractor</td>
		</tr>
		<tr>
			<td>Microscopic tweezers</td>
			<td>RWD</td>
			<td>F12006-10</td>
			<td>Used for penetrating and separating the tissue to open operation space</td>
		</tr>
		<tr>
			<td>Needle holder</td>
			<td>RWD</td>
			<td>F12005-10</td>
			<td>Used for pinching off the tip of gauge needle and blunting it</td>
		</tr>
		<tr>
			<td>Ophthalmic forceps</td>
			<td>RWD</td>
			<td>F14012-10&#160;</td>
			<td>Used for holding skin and other tissues</td>
		</tr>
		<tr>
			<td>Ophthalmic scissors</td>
			<td>RWD</td>
			<td>S11001-08</td>
			<td>Used for making sking incision of mouse</td>
		</tr>
		<tr>
			<td>Pentobarbital sodium</td>
			<td>Sigma</td>
			<td>P3761</td>
			<td>Used for mouse anesthesia</td>
		</tr>
		<tr>
			<td>Sterile operating mat</td>
			<td>Hale &#38; hearty</td>
			<td>211002</td>
			<td>Used for placing animal during surgery</td>
		</tr>
		<tr>
			<td>Ultra-sound imaging system</td>
			<td>Fujifilm visualsonics</td>
			<td>vevo1100</td>
			<td>Used for measure the blood flow velocity, left ventricular wall thickness and ejection fraction, https://www.visualsonics.com/product/imaging-systems/vevo-1100</td>
		</tr>
	</tbody>
</table>

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.

After successful TAC surgery, pressure overload was detected using an ultrasound imaging system. Four weeks after surgery, mice develop decreased heart function. In the present study, the efficacy of TAC surgery was validated via ejection fraction (EF), fractional shortening (FS), left ventricular mass (LV mass) and left ventricular internal diameter (LVID) of mice who underwent TAC surgery after 4 weeks. EF was significantly reduced in TAC mice after 4 weeks compared to sham mice (47% &#177; 10% vs. 78% &#177; ...

Watch this Scientific Journal Video about A Modified Technique for Transverse Aortic Constriction in Mice at JoVE.com

A Modified Technique for Transverse Aortic Constriction in Mice

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 ...

This protocol provides a rapid surgical trauma limited, uncomplicated, and inexpensive masses to perform TAC surgery. This model approaches the aortic arch using a self-made retractor and does not need microsurgical scale or mechanical ventilation, thereby significant limiting surgical trauma. To begin, prepare a five milliliter syringe.Then make the needle blunt by pinching off its tip with a needle holder. Prepare a 27 gauge needle blunted with a needle holder and bend its tip at 90 degrees. Use a commercially obtained iron wire and twine it around the needle.Form a small snare or loop at the blunted tip of the needle. Sterilize all the surgical tools before surgery by autoclaving. Confirm the depth of anesthesia with a toe pinch to prevent dryness while under anesthesia.Apply ophthalmic ointment to both eyes. Then place the mouse in the supine position on a heating pad covered with a sterile drape with its head pointing to the operator. Fix its extremities with adhesive tape and incisors with a 4-0 suture.Now, insert a rectal probe to monitor body temperature during the operation. Using sterilized ophthalmic scissors, cut a hole in a new, disposable sterile drape. Place the sterile drape over the mouse and ensure the un-haired operating field is visible through the hole.After making an incision separate the skin and the superficial fascia and expose the trachea and proximal sternal. Then carefully make a three to four millimeter longitudinal midline incision to the sternum from the upper edge to the sternal angle and gently lift the sternum with forceps. Using straight forceps bluntly dissect the target vessel and tissues around it.Now, hold the previously self-made retractor with a wire snare in the right hand. Carefully pass the snare of the retractor under the aorta between the left common carotid artery and the origin of the right denominate artery. Pass the retractor to the left hand.Hold the microscopic tweezers in the right hand and pass a 7-0 silk suture through the snare loop at the end. Pull out the retractor. Place a 27 gauge needle parallel to the aorta and tie the suture around the needle and the aorta.Then hold the 27 gauge needle with ophthalmic forceps and the knot tied to the 27 gauge needle and aorta with another forceps. Quickly but gently pull the 27 gauge needle from the ligation. Suture the skin with 4-0 synthetic monofilament suture in an interrupted suture pattern.Place the mouse on a warm pad and wait for it to revive. Generally, the mouse revives in about 60 minutes. After four weeks of surgery.Ejection fraction and fractional shortening were significantly reduced in transverse aortic constriction mice compared to sham mice. However, left ventricular mass and left ventricular internal diameter were significantly elevated in the transverse aortic constriction mice. The most important step in this particle is passing suture under the aortic arch.All movies must be gentle to reduce unnecessary traction to the artery. Following this procedure researchers can apply medical treatment to the animal model in order to investigate potential therapeutic targets to patients with cardio hypertrophy or heart failure.

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Research

JoVE Journal

Biology

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 ...

Evaluation of Respiratory System Mechanics in Mice using the Forced Oscillation Technique

The forced oscillation technique (FOT) is a powerful, integrative and translational tool permitting the experimental assessment of lung function in mice in a comprehensive, detailed, precise and reproducible manner. It provides measurements of respiratory system mechanics through the analysis of pressure and volume signals acquired in reaction to predefined, small amplitude, oscillatory airflow waveforms, which are typically applied at the subject's airway opening. The present protocol details the steps required to adequately execute forced oscillation measurements in mice using a computer-controlled piston ventilator (flexiVent; SCIREQ Inc, Montreal, Qc, Canada). The description is divided into four parts: preparatory steps, mechanical ventilation, lung function measurements, and data analysis. It also includes details of how to assess airway responsiveness to inhaled methacholine in anesthetized mice, a common application of this technique which also extends to other outcomes and various lung pathologies. Measurements obtained in na&iuml;ve mice as well as from an oxidative-stress driven model of airway damage are presented to illustrate how this tool can contribute to a better characterization and understanding of studied physiological changes or disease models as well as to applications in new research areas.

The present protocol provides a detailed step-by-step description of the procedures required to execute measurements of respiratory system mechanics as well as the assessment of airway responsiveness to inhaled methacholine in mice using the forced oscillation technique (flexiVent; SCIREQ Inc, Montreal, Qc, Canada).

The  forced oscillation technique (FOT) is a powerful, integrative and translational  tool permitting the experimental assessment of lung function in mice ...

A New Technique for Quantitative Analysis of Hair Loss in Mice Using Grayscale Analysis

Alopecia is a common form of hair loss which can occur in many different conditions, including male-pattern hair loss, polycystic ovarian syndrome, and alopecia areata. Alopecia can also occur as a side effect of chemotherapy in cancer patients. In this study, our goal was to develop a consistent and reliable method to quantify hair loss in mice, which will allow investigators to accurately assess and compare new therapeutic approaches for these various forms of alopecia. The method utilizes a standard gel imager to obtain and process images of mice, measuring the light absorption, which occurs in rough proportion to the amount of black (or gray) hair on the mouse. Data that has been quantified in this fashion can then be analyzed using standard statistical techniques (i.e., ANOVA, T-test). This methodology was tested in mouse models of chemotherapy-induced alopecia, alopecia areata and alopecia from waxing. In this report, the detailed protocol is presented for performing these measurements, including validation data from C57BL/6 and C3H/HeJ strains of mice. This new technique offers a number of advantages, including relative simplicity of application, reliance on equipment which is readily available in most research laboratories, and applying an objective, quantitative assessment which is more robust than subjective evaluations. Improvements in quantification of hair growth in mice will improve study of alopecia models and facilitate evaluation of promising new therapies in preclinical studies.

Alopecia is a common form of hair loss which can occur in many different conditions, including as a side-effect of chemotherapy. We have developed a method to quantify hair loss in mice, utilizing a standard gel imager to perform a grayscale analysis, to facilitate study of promising new alopecia therapies.

Alopecia is a common form of hair loss which can occur in many different conditions, including male-pattern hair loss, polycystic ovarian syndrome, and ...

Induction of Right Ventricular Failure by Pulmonary Artery Constriction and Evaluation of Right Ventricular Function in Mice

The mechanism of right ventricular failure (RVF) requires clarification due to the uniqueness, high morbidity, high mortality, and refractory nature of RVF. Previous rat models imitating RVF progression have been described. Compared with rats, mice are more accessible, economical, and widely used in animal experiments. We developed a pulmonary artery constriction (PAC) approach which is comprised of banding the pulmonary trunk in mice to induce right ventricular (RV) hypertrophy. A special surgical latch needle was designed that allows for easier separation of the aorta and the pulmonary trunk. In our experiments, the use of this fabricated latch needle reduced the risk of arteriorrhexis and improved the surgical success rate to 90%. We used different padding needle diameters to precisely create quantitative constriction, which can induce different degrees of RV hypertrophy. We quantified the degree of constriction by evaluating the blood flow velocity of the PA, which was measured by noninvasive transthoracic echocardiography. RV function was precisely evaluated by right heart catheterization at 8 weeks after surgery. The surgical instruments made inhouse were composed of common materials using a simple process that is easy to master. Therefore, the PAC approach described here is easy to imitate using instruments made in the lab and can be widely used in other labs. This study presents a modified PAC approach that has a higher success rate than other models and an 8-week postsurgery survival rate of 97.8%. This PAC approach provides a useful technique for studying the mechanism of RVF and will enable an increased understanding of RVF.

Here, we provide a useful approach for studying the mechanism of right ventricular failure. A more convenient and efficient approach to pulmonary artery constriction is established using surgical instruments made inhouse. In addition, methods to evaluate the quality of this approach by echocardiography and catheterization are provided.

The mechanism of right ventricular failure (RVF) requires clarification due to the uniqueness, high morbidity, high mortality, and refractory nature of ...

Modified Methods for Loading of High-Throughput DNA Extraction Plates Reduce Potential for Contamination

High-throughput DNA sequencing techniques have contributed substantially to advances in our understanding of relationships among microbial communities, host characteristics, and broader ecosystem functions. With this rapid increase in breadth and depth of sequencing capabilities have come methods to extract, amplify, analyze, and interpret environmental DNA successfully with maximum efficiency. Unfortunately, performing DNA extractions quickly can come at the cost of increasing the risk of contamination among samples. In particular, high-throughput extractions that are based on samples contained in a 96-well plate offer a relatively quick method, compared to single-tube extractions, but also increase opportunities for well-to-well cross-contamination. To minimize the risk of cross-contamination among samples, while retaining the benefits of high-throughput extraction techniques, we developed a new method for loading environmental samples into 96-well plates. We used pierceable PCR sealing films to cover each plate while loading samples and added samples first to PCR tubes before moving them into wells; together, these practices reduce the risk of sample drift and unintended double loading of wells. The method outlined in this paper provides researchers with an approach to maximize available high-throughput extraction techniques while reducing the risk of cross-contamination inherent to 96-well plates. We provide a detailed step by step outline of how to move from sample collection to DNA extraction while minimizing the risk of unwanted cross-contamination.

Current methods for loading 96-well plates for DNA extractions can be prone to contamination. We detail a new method for loading 96-well plates that reduces risk of cross-contamination among wells. Our method will help other researchers capitalize on the efficiency of high-throughput DNA extraction techniques and minimize risk of contamination.

High-throughput DNA sequencing techniques have contributed substantially to advances in our understanding of relationships among microbial communities, ...

A Modified Surgical Model of Hind Limb Ischemia in ApoE-/- Mice using a Miniature Incision

The purpose of this study is to introduce and evaluate a modified surgical approach to induce acute ischemia in mice that can be implemented in most animal laboratories.&#160;Contrary to the conventional approach for double ligation of the femoral artery (DLFA), a smaller incision on the right inguinal region was made to expose the proximal femoral artery (FA) to perform DLFA. Then, using a 7-0 suture, the incision was dragged to the knee region to expose the distal FA. Magnetic resonance imaging (MRI) on bilateral hind limbs was used to detect FA occlusion after the surgery. At 0, 1, 3, 5, and 7 days after the surgery, functional recovery of the hind limbs was visually assessed and graded using the Tarlov scale. Histologic evaluation was performed after euthanizing the animals 7 days after DLFA. The procedures were successfully performed on the right leg in ten ApoE-/- mice, and no mice died during subsequent observation. The incision sizes in all 10 mice were less than 5 mm (4.2 &#177; 0.63 mm). MRI results showed that FA blood flow in the ischemic side was clearly blocked. The Tarlov scale results demonstrated that hind limb function significantly decreased after the procedure and slowly recovered over the following 7 days. Histologic evaluation showed a significant inflammatory response on the ischemic side and reduced microvascular density in the ischemic hind limb. In conclusion, this study introduces a modified technique using a miniature incision to perform hind limb ischemia (HLI) using DLFA.

A Modified Surgical Model of Hind Limb Ischemia in ApoE-/- Mice using a Miniature Incision

This article demonstrates an efficient surgical approach to establish acute ischemia in mice with a small incision. This approach can be applied by most research groups without any laboratory upgrades.

The purpose of this study is to introduce and evaluate a modified surgical approach to induce acute ischemia in mice that can be implemented in most ...

A Calcium Phosphate-Induced Mouse Abdominal Aortic Aneurysm Model

An abdominal aortic aneurysm (AAA) is a life-threatening cardiovascular disease that occurs worldwide and is characterized by irreversible dilation of the abdominal aorta. Currently, several chemically induced murine AAA models are used, each simulating a different aspect of the pathogenesis of AAA. The calcium phosphate-induced AAA model is a rapid and cost-effective model compared to the angiotensin II- and elastase-induced AAA models. The application of CaPO4 crystals to the mouse aorta results in elastic fiber degradation, loss of smooth muscle cells, inflammation, and calcium deposition associated with aortic dilation. This article introduces a standard protocol for the CaPO4-induced AAA model. The protocol includes material preparation, the surgical application of the CaPO4&#160;to the adventitia of the infrarenal abdominal aorta, the harvesting of aortas to visualize aortic aneurysms, and histological analyses in mice.

This protocol describes a calcium phosphate-induced abdominal aortic aneurysm (AAA) mouse model to study the pathological features and molecular mechanisms of AAAs.

An abdominal aortic aneurysm (AAA) is a life-threatening cardiovascular disease that occurs worldwide and is characterized by irreversible dilation of the ...

Manipulation of Rhythmic Food Intake in Mice Using a Custom-Made Feeding System

Rhythmic gene expression is a hallmark of the circadian rhythm and is essential for driving the rhythmicity of biological functions at the appropriate time of day. Studies over the last few decades have shown that rhythmic food intake (i.e., the time at which organisms eat food during the 24 h day), significantly contributes to the rhythmic regulation of gene expression in various organs and tissues throughout the body. The effects of rhythmic food intake on health and physiology have been widely studied ever since and have revealed that restricting food intake for 8 h during the active phase attenuates metabolic diseases arising from a variety of obesogenic diets. These studies often require the use of controlled methods for timing the delivery of food to animals. This manuscript describes the design and use of a low-cost and efficient system, built in-house for measuring daily food consumption as well as manipulating rhythmic food intake in mice. This system entails the use of affordable raw materials to build cages suited for food delivery, following a user-friendly handling procedure. This system can be used efficiently to feed mice on different feeding regimens such as ad libitum, time-restricted, or arrhythmic schedules, and can incorporate a high-fat diet to study its effect on behavior, physiology, and obesity. A description of how wild-type (WT) mice adapt to the different feeding regimens is provided.

Restricting the timing of food intake has emerged as a promising intervention to attenuate diet-induced metabolic diseases. This manuscript details the construction and use of an efficient system built in-house for measuring and manipulating rhythmic food intake in mice.

Rhythmic gene expression is a hallmark of the circadian rhythm and is essential for driving the rhythmicity of biological functions at the appropriate ...

Establishing a Diaphyseal Femur Fracture Model in Mice

Bones have a significant regenerative capacity. However, fracture healing is a complex process, and depending on the severity of the lesions and the age and overall health status of the patient, failures can occur, leading to delayed union or nonunion. Due to the increasing number of fractures resulting from high-energy trauma and aging, the development of innovative therapeutic strategies to improve bone repair based on the combination of skeletal/mesenchymal stem/stromal cells and biomimetic biomaterials is urgently needed. To this end, the use of reliable animal models is fundamental to better understanding the key cellular and molecular mechanisms that determine the healing outcomes. Of all the models, the mouse is the preferred research model because it offers a wide variety of transgenic strains and reagents for experimental analysis. However, the establishment of fractures in mice may be technically challenging due to their small size. Therefore, this article aims to demonstrate the procedures for the surgical establishment of a diaphyseal femur fracture in mice, which is stabilized with an intramedullary wire and resembles the most common bone repair process, through cartilaginous callus formation.

This protocol describes a surgical procedure for the establishment of a diaphyseal fracture in the femur of mice, which is stabilized with an intramedullary wire, for fracture healing studies.

Bones have a significant regenerative capacity. However, fracture healing is a complex process, and depending on the severity of the lesions and the age ...

3D Visualization of Bone Remodeling Under Tensile Load in Suture Expansion Mice

A 3-D Visualization Technique for Bone Remodeling in a Suture Expansion Mouse Model

Craniofacial sutures play a crucial role beyond being fibrous joints connecting craniofacial bones; they also serve as the primary niche for calvarial and facial bone growth, housing mesenchymal stem cells and osteoprogenitors. As most craniofacial bones develop through intramembranous ossification, the sutures' marginal regions act as initiation points. Due to this significance, these sutures have become intriguing targets in orthopedic therapies like spring-assisted cranial vault expansion, rapid maxillary expansion, and maxillary protraction. Under orthopedic tracing force, suture stem cells are rapidly activated, becoming a dynamic source for bone remodeling during expansion. Despite their importance, the physiological changes during bone remodeling periods remain poorly understood. Traditional sectioning methods, primarily in the sagittal direction, do not capture the comprehensive changes occurring throughout the entire suture. This study established a standard mouse model for sagittal suture expansion. To fully visualize bone remodeling changes post-suture expansion, the PEGASOS tissue clearing method was combined with whole-mount EdU staining and calcium chelating double labeling. This allowed the visualization of highly proliferating cells and new bone formation across the entire calvarial bones following expansion. This protocol offers a standardized suture expansion mouse model and a 3-D visualization method, shedding light on the mechanobiological changes in sutures and bone remodeling under tensile force loading.

Author Spotlight: PEGASOS Tissue Clearing Technique to Visualize Bone Remodeling 

This protocol presents a standardized suture expansion mouse model and a 3-D visualization method to study the mechanobiological changes of the suture and bone remodeling under tensile force loading.

Craniofacial sutures play a crucial role beyond being fibrous joints connecting craniofacial bones; they also serve as the primary niche for calvarial and ...