TWP was funded by the Irish Cardiac Society Brian McGovern Travelling Fellowship. WTP was funded by R01 HL095712 and an AHA Established Investigator Award.

All described steps were performed under protocols approved by the Institutional Animal Care and Use Committee of Boston Children&#8217;s Hospital.
1. Preparation
<ol>
	<li>Perform baseline cardiac anatomical and functional assessment by echocardiography prior to beginning the injection protocol, as the optimal fixed transducer position for intramyocardial injection may not yield the optimal standard views for delineating anatomy and assessment of function.</li>
	<li>The injection setup is shown in Figures 1A-1C. Place an empty syringe with a sheathed needle, bevel oriented upwards, in the syringe clamp (see Figure 1C) and secure the ultrasound transducer probe in the scan-head clamp (see Figure 1B). Loosen the scan-head clamp ball lock joint (Figure 1B) and manipulate the transducer orientation so that it is aligned parallel to the axis of the needle. Fix the scan-head position by tightening the scan-head clamp ball lock joint. 
	NOTE: For injection in adult mice, a 30 G needle with a 1 in/2.5 cm length is optimal. A 1 ml syringe can be used for larger volumes, while a gastight syringe can be used for more precise control of smaller volumes (5-10 &#181;l).</li>
	<li>Apply ultrasound gel liberally to the transducer tip with a spatula to cover the head along its entirety. Carefully unsheathe the needle and use the needle mount controls to advance the needle directly under the transducer and within the ultrasound gel for visualization. Make minor adjustments using the needle mount control so that the needle is visualized clearly along its length on the ultrasound image. If the transducer was properly aligned parallel to the needle in step 1.4, then the needle should remain within the imaging plane as it is advanced and withdrawn with the injection control knob (Figure 1C).</li>
	<li>In subsequent steps, do not disturb the needle/transducer horizontal alignment by moving either in the horizontal axis. Rather, target specific areas of the heart for injection by changing the vertical (y-axis) position of the needle mount and by moving the animal platform.</li>
	<li>Move the transducer superiorly from the animal platform using the scan height control (Figure 1B) to allow subsequent placement of the anesthetized mouse onto the animal platform. This will not disrupt the x-axis alignment of the transducer to the long axis of the needle.</li>
	<li>Remove the syringe that was used for alignment from the syringe clamp and discard carefully. Load the new needle and syringe with the injectate to the final target volume, allowing for dead space in the syringe tip. Be careful to remove air bubbles. Place the syringe into the syringe clamp without adjusting its x-axis alignment. Fully retract the syringe using the injection control. 
	NOTE: For initial training purposes, the use of Evan&#8217;s blue dye (1%), Trypan blue stain (0.4%) or a suspension of fluorescent microspheres as the injectate can assist the operator in confirming competency and success of targeted injection.</li>
</ol>
2. Injection
<ol>
	<li>Turn on the integrated warmer of the heating platform and set it for 37 &#176;C. Place the animal platform 180&#176; from the usual imaging orientation, with the anesthesia hose clamp and head of the animal closest to the operator. This allows the heart (in the left side of the chest) to be ipsilateral to the syringe clamp and needle. Note: Additional minor clockwise rotational adjustments to the animal platform may be necessary to orient the heart correctly for the parasternal short axis imaging plane that will be used for injection (Figure 2A).</li>
	<li>Prepare mice for echocardiography as previously reported9. Anesthetize the mouse in an induction chamber with 2% isoflurane. Remove chest hair with hair removal cream and apply lubricating gel to both eyes to prevent drying of the sclera.</li>
	<li>Raise the transducer using the scan head height control (Figure 1B). Place the anesthetized mouse supine atop the heated animal platform with the snout within a nose cone delivering 1-3% isoflurane (Figures 2A-2B). Gently insert a rectal probe and tape the four paws to the ECG electrodes, applying electrode gel for electrical contact. 
	NOTE: An appropriate level of anesthesia must be ensured for the humane treatment of the animal. There should be no change in heart rate and no response to placement of the needle through the chest wall. The animal platform&#8217;s integrated homeostatic temperature controls should be used to maintain normothermia (37&#160;&#177; 0.5 &#176;C), as hypothermia will result in relative bradycardia, ventricular dilatation, and possible discomfort.</li>
	<li>Once the mouse is secure on the animal platform, lower the transducer onto the depilated chest using the scan head height control (Figure 1B). The optimal ultrasound setup for injection is for the heart to be visualized in the parasternal short axis orientation, as per standard echocardiographic technique. Rotate the animal platform 20-30&#176; clockwise to obtain the optimal acoustic window for injection in the short axis imaging plane (Figures 2A-2B). Note: Alternatively, injection can be performed from a parasternal long axis orientation by counter-clockwise rotation of the animal platform (Figure 2C).</li>
	<li>Use the animal platform adjustment controls to adjust the field of view and to target any desired injection site in the left ventricular myocardium. Pan back-and-forth from the apex to the base of heart to target the desired injection location in the left ventricular myocardium (Figures 3A-3C). Note: The midpapillary parasternal short-axis view (Figure 3A) offers reproducible landmarks that permit followup imaging of the injection site. Note: Alternatively, the parasternal long axis view can be used to target a predefined injection site (Figure 3D).</li>
	<li>Starting with the syringe in the fully retracted syringe clamp, slowly advance the syringe towards the animal&#8217;s chest by turning the injection control clockwise (Figure 4A). To permit clear ultrasound visualization of both the heart and the needle tip as it approaches the chest, use plenty of ultrasound gel over the left side of the chest and optimize the acoustic window by setting a wide field of view on the echocardiography controls. Set the focal point/zone at the target site for injection. Minor adjustments to the needle mount controls can optimize the image of the needle along its length. 
	NOTE: Some ultrasound machines have a needle guide software function to digitally extend a line along the long axis of the needle through to the target myocardium (Figure 4B). Such a software tool can be helpful but is not essential.</li>
	<li>With the animal appropriately sedated (1-3% isoflurane mixed with 0.5-0.8 L/min 100% oxygen), advance the needle through the chest wall of the mouse and into the myocardium, carefully observing the position of the beveled needle tip at all times. Stop advancing when the needle tip is within the target myocardium (Figure 4C). The whole beveled tip should be securely within the myocardium, to avoid injectate leak into the pericardial space.</li>
	<li>When the tip is in the desired location, deliver the injectate by pushing on the syringe plunger. Deliver the injectate slowly, over 5-30 sec (depending on the volume being delivered). Up to 50 &#181;l of injectate can be delivered without compromising ventricular function. A transient echobright appearance to the injected myocardial region may be evident after successful injection. A brief (seconds) period of relative bradycardia is occasionally noted with injection into the myocardium and quickly resolves.</li>
	<li>Once the injectate has been administered, promptly withdraw the needle by counter-clockwise rotation of the injection control knob. The mouse should be kept under anesthesia for several minutes of echocardiographic observation to confirm preserved ventricular function and no postprocedural complications. If indicated, multiple regions of myocardium can be serially injected by repositioning of the needle&#8217;s angle of approach by adjustment of the animal platform. After intramyocardial injection, the mouse is placed in a cage on its own and allowed to recover from anesthesia under observation.</li>
	<li>Do not leave an animal unattended until it has regained sufficient consciousness to maintain sternal recumbency. Do not return an animal that has undergone intramyocardial injection to the company of other animals until fully recovered. The cage should be placed on a thermoregulated pad with ready provision of water and mouse diet. Postprocedural discomfort is not expected and failure to appropriately resume normal behavior shortly after intervention suggests a potential complication (see Discussion).</li>
	<li>Carefully discard the needle immediately after completion of intramyocardial injection to minimize the risk of sharps injury to the operator or bystanders. Reusing a needle can result in blunting of the tip making it more challenging to pierce the myocardium and resulting in a higher risk of complication.</li>
</ol>

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E., Steinhoff, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=10+years+of+intracoronary+and+intramyocardial+bone+marrow+stem+cell+therapy+of+the+heart:+from+the+methodological+origin+to+clinical+practice.">10 years of intracoronary and intramyocardial bone marrow stem cell therapy of the heart: from the methodological origin to clinical practice.</a> J Am Coll Cardiol. 58, 1095-1104 (2011).</li><li>Cheng, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intramyocardial+autologous+cell+engraftment+in+patients+with+ischaemic+heart+failure:+a+meta-analysis+of+randomised+controlled+trials.">Intramyocardial autologous cell engraftment in patients with ischaemic heart failure: a meta-analysis of randomised controlled trials.</a> Heart Lung Circ. 22 (11), 887-894 (2013).</li><li>Fischer-Rasokat, U., 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+pilot+trial+to+assess+potential+effects+of+selective+intracoronary+bone+marrow-derived+progenitor+cell+infusion+in+patients+with+nonischemic+dilated+cardiomyopathy:+final+1-year+results+of+the+transplantation+of+progenitor+cells+and+functional+regeneration+enhancement+pilot+trial+in+patients+with+nonischemic+dilated+cardiomyopathy.">A pilot trial to assess potential effects of selective intracoronary bone marrow-derived progenitor cell infusion in patients with nonischemic dilated cardiomyopathy: final 1-year results of the transplantation of progenitor cells and functional regeneration enhancement pilot trial in patients with nonischemic dilated cardiomyopathy.</a> Circ Heart Fail. 2, 417-423 (2009).</li><li>Seth, 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=Percutaneous+intracoronary+cellular+cardiomyoplasty+for+nonischemic+cardiomyopathy:+clinical+and+histopathological+results:+the+first-in-man+ABCD+(autologous+bone+marrow+cells+in+dilated+cardiomyopathy)+trial.">Percutaneous intracoronary cellular cardiomyoplasty for nonischemic cardiomyopathy: clinical and histopathological results: the first-in-man ABCD (autologous bone marrow cells in dilated cardiomyopathy) trial.</a> J Am Coll Cardiol. 48, 2350-2351 (2006).</li><li>Ladage, D., 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=Percutaneous+methods+of+vector+delivery+in+preclinical+models.">Percutaneous methods of vector delivery in preclinical models.</a> Gene Ther. 19, 637-641 (2012).</li><li>Zangi, 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=Modified+mRNA+directs+the+fate+of+heart+progenitor+cells+and+induces+vascular+regeneration+after+myocardial+infarction.">Modified mRNA directs the fate of heart progenitor cells and induces vascular regeneration after myocardial infarction.</a> Nat Biotechnol. 31, 898-907 (2013).</li><li>Laakmann, 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=Minimally+invasive+closed-chest+ultrasound-guided+substance+delivery+into+the+pericardial+space+in+mice.">Minimally invasive closed-chest ultrasound-guided substance delivery into the pericardial space in mice.</a> Naunyn Schmiedebergs Arch Pharmacol. 386 (3), 227-238 (2013).</li><li>Respress, J. L., 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=Transthoracic+echocardiography+in+mice.">Transthoracic echocardiography in mice.</a> J Vis Exp. (39), e1738 (2010).</li><li>Wang, 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=Characterization+of+cis-regulating+elements+and+trans-activating+factors+of+the+rat+cardiac+troponin+T+gene.">Characterization of cis-regulating elements and trans-activating factors of the rat cardiac troponin T gene.</a> J Biol Chem. 269, 30595-30603 (1994).</li><li>Shimshek, D. 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=Codon-improved+Cre+recombinase+(iCre)+expression+in+the+mouse.">Codon-improved Cre recombinase (iCre) expression in the mouse.</a> Genesis. 32, 19-26 (2002).</li><li>Lichtenauer, 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=Intravenous+and+intramyocardial+injection+of+apoptotic+white+blood+cell+suspensions+prevents+ventricular+remodelling+by+increasing+elastin+expression+in+cardiac+scar+tissue+after+myocardial+infarction.">Intravenous and intramyocardial injection of apoptotic white blood cell suspensions prevents ventricular remodelling by increasing elastin expression in cardiac scar tissue after myocardial infarction.</a> Basic Res Cardiol. 106 (4), 645-655 (2011).</li><li>Herrmann, J. 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=Postinfarct+intramyocardial+injection+of+mesenchymal+stem+cells+pretreated+with+TGF-alpha+improves+acute+myocardial+function.">Postinfarct intramyocardial injection of mesenchymal stem cells pretreated with TGF-alpha improves acute myocardial function.</a> Am J Physiol Regul Integr Comp Physiol. 299 (1), 371-378 (2010).</li><li>Zhou, 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=Direct+injection+of+autologous+mesenchymal+stromal+cells+improves+myocardial+function.">Direct injection of autologous mesenchymal stromal cells improves myocardial function.</a> Biochem Biophys Res Commun. 390 (3), 902-907 (2009).</li><li>Campbell, N. 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The authors have nothing to disclose.

Biologics can be delivered to the myocardium by direct intramyocardial injection, intrapericardial injection, or indirect administration via the bloodstream. Recent cell based therapy trials in myocardial infarction models have described an open thoracotomy approach to the delivery of injectate12-14. An important factor in the success of a myocardial therapeutic intervention hinges on the choice of delivery route. The highest local dose of biologic is achieved by intramyocardial delivery15,16. Intra...

Heart disease is the leading cause of death for both men and women in the United States, accounting for 600,000 deaths annually1. Murine models of cardiovascular disease are critically important for investigating pathophysiological mechanisms and for exploring potential therapies. Myocardial delivery of gene therapy vectors, stem cells, modified RNAs, and other therapeutic agents permits investigation of their therapeutic potential for heart disease2-7. Currently, there are limited options for myocardial delivery of therapeutic agents in mouse models6. Intramyocardial injection under direct visualization is commonly used, but requires a sternotomy or thoracotomy and is limited to the exposed region of the heart. While convenient when performed at the time of another experimental manipulation such as LAD ligation, the need for an invasive procedure for intramyocardial delivery limits potential experimental designs and introduces additional effects from the procedure (e.g., fibrosis due to thoracotomy). Percutaneous pericardial delivery of viral vectors has been reported, but the site and distribution of therapeutic agent is not homogeneous and is difficult to control8. Percutaneous coronary injection results in more homogenous distribution of injected material, but efficient and reproducible coronary delivery is challenging in murine models.
Here, we describe a closed chest intramyocardial injection technique that allows minimally invasive, operator controlled targeting of therapeutic agents under ultrasound guidance. The technique is easy to learn, obviates the need for thoracotomy or sternotomy and their attendant experimental complications, and provides greater flexibility on the timing and sites of intramyocardial injection. Thus, echocardiography-assisted intramyocardial injection represents a technically simple and highly effective method of manipulating the myocardium in murine experimental models.

<table border="0" cellpadding="0" cellspacing="0" width="743">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Vevo 2100 ultrasound imaging system&#160;</td>
			<td style="width:144px;">Visualsonics</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Vevo Integrated Rail System III</td>
			<td style="width:144px;">Visualsonics</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Microscan MS400 transducer</td>
			<td style="width:144px;">Visualsonics</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Microscan MS550D transducer</td>
			<td style="width:144px;">Visualsonics</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">PrecisionGlide needles</td>
			<td style="width:144px;">BD</td>
			<td style="width:119px;">305128</td>
			<td>30G x 1 inch</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">1cc slip tip syringe</td>
			<td style="width:144px;">Exel International&#160;</td>
			<td style="width:119px;">26048</td>
			<td>or equivalent</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Gastight 50ul glass syringes</td>
			<td style="width:144px;">Hamilton&#160;</td>
			<td style="width:119px;">1705</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Trypan blue stain (0.4%)</td>
			<td style="width:144px;">Gibco&#160;</td>
			<td style="width:119px;">15250</td>
			<td>or equivalent</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Isoflurane</td>
			<td style="width:144px;">Baxter</td>
			<td style="width:119px;">AHN3640</td>
			<td>or equivalent</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Aquasonic 100</td>
			<td style="width:144px;">Parker Laboratories</td>
			<td style="width:119px;">(01-08)</td>
			<td>or equivalent</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Polystyrene microspheres (red fluorescent)</td>
			<td style="width:144px;">Life Technologies</td>
			<td style="width:119px;">F-8842</td>
			<td>or equivalent</td>
		</tr>
	</tbody>
</table>

ultrasound-guided transthoracic intramyocardial injection in mice

Murine models of cardiovascular disease are important for investigating pathophysiological mechanisms and exploring potential regenerative therapies. Experiments involving myocardial injection are currently performed by direct surgical access through a thoracotomy. While convenient when performed at the time of another experimental manipulation such as coronary artery ligation, the need for an invasive procedure for intramyocardial delivery limits potential experimental designs. With ever improving ultrasound resolution and advanced noninvasive imaging modalities, it is now feasible to routinely perform ultrasound-guided, percutaneous intramyocardial injection. This modality efficiently and reliably delivers agents to a targeted region of myocardium. Advantages of this technique include the avoidance of surgical morbidity, the facility to target regions of myocardium selectively under ultrasound guidance, and the opportunity to deliver injectate to the myocardium at multiple, predetermined time intervals. With practiced technique, complications from intramyocardial injection are rare, and mice quickly return to normal activity on recovery from anesthetic. Following the steps outlined in this protocol, the operator with basic echocardiography experience can quickly become competent in this versatile, minimally invasive technique.

Murine Intramyocardial Injection with Blue Dye or Fluorescent Microspheres
Injection of Evan&#8217;s blue dye is useful for training purposes. Soon after injection, euthanize the mouse and remove the heart to visualize the location of the injected blue dye. Figure 5 shows an example of a successful injection, with blue dye infiltrating the myocardium at the mid-papillary muscle level (Figure 5A, region enclosed by dotted line). Evans blue dye will wash out of the...

Watch this Scientific Journal Video about Ultrasound-guided Transthoracic Intramyocardial Injection in Mice at JoVE.com

Ultrasound-guided Transthoracic Intramyocardial Injection in Mice

Echocardiography-guided percutaneous intramyocardial injection represents an efficient, reliable, and targetable modality for the delivery of gene transfer agents or cells into the murine heart. Following the steps outlined in this protocol, the operator can quickly become competent in this versatile, minimally invasive technique.

Murine models of cardiovascular disease are important for investigating pathophysiological mechanisms and exploring potential regenerative therapies. ...

ultrasound-guided-transthoracic-intramyocardial-injection-in-mice

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14.8K Views.  Boston Children's Hospital. Echocardiography-guided percutaneous intramyocardial injection represents an efficient, reliable, and targetable modality for the delivery of gene transfer agents or cells into the murine heart. Following the steps outlined in this protocol, the operator can quickly become competent in this versatile, minimally invasive technique.

Video: Ultrasound-guided Transthoracic Intramyocardial Injection in Mice

Transthoracic Echocardiography in Mice

In recent years, murine models have become the primary avenue for studying the molecular mechanisms of cardiac dysfunction resulting from changes in gene expression. Transgenic and gene targeting methods can be used to generate mice with altered cardiac size and function,1-3 and as a result, in vivo techniques are needed to evaluate their cardiac phenotype. Transthoracic echocardiography, pulse wave Doppler (PWD), and tissue Doppler imaging (TDI) can be used to provide dimensional measurements of the mouse heart and to quantify the degree of cardiac systolic and diastolic performance. Two-dimensional imaging is used to detect abnormal anatomy or movements of the left ventricle, whereas M-mode echo is used for quantification of cardiac dimensions and contractility.4,5 In addition, PWD is used to quantify localized velocity of turbulent flow,6 whereas TDI is used to measure the velocity of myocardial motion.7 Thus, transthoracic echocardiography offers a comprehensive method for the noninvasive evaluation of cardiac function in mice.

Transthoracic echocardiography offers a noninvasive method for the evaluation of cardiac function in mice. A combination of ultrasound and Doppler imaging modalities can be used to obtain dimensional measurements of the heart and intracardiac blood flow, which together provide an assessment of cardiac systolic and diastolic performance.

In recent years, murine models have become the primary avenue for studying the molecular mechanisms of cardiac dysfunction resulting from changes in gene ...

Coronary Artery Ligation and Intramyocardial Injection in a Murine Model of Infarction

Mouse models are a valuable tool for studying acute injury and chronic remodeling of the myocardium in vivo. With the advent of genetic modifications to the whole organism or the myocardium and an array of biological and/or synthetic materials, there is great potential for any combination of these to assuage the extent of acute ischemic injury and impede the onset of heart failure pursuant to myocardial remodeling. 
Here we present the methods and materials used to reliably perform this microsurgery and the modifications involved for temporary (with reperfusion) or permanent coronary artery occlusion studies as well as intramyocardial injections. The effects on the heart that can be seen during the procedure and at the termination of the experiment in addition to histological evaluation will verify efficacy. 
Briefly, surgical preparation involves anesthetizing the mice, removing the fur on the chest, and then disinfecting the surgical area. Intratracheal intubation is achieved by transesophageal illumination using a fiber optic light. The tubing is then connected to a ventilator. An incision made on the chest exposes the pectoral muscles which will be cut to view the ribs. For ischemia/reperfusion studies, a 1 cm piece of PE tubing placed over the heart is used to tie the ligature to so that occlusion/reperfusion can be customized. For intramyocardial injections, a Hamilton syringe with sterile 30gauge beveled needle is used. When the myocardial manipulations are complete, the rib cage, the pectoral muscles, and the skin are closed sequentially. Line block analgesia is effected by 0.25% marcaine in sterile saline which is applied to muscle layer prior to closure of the skin. The mice are given a subcutaneous injection of saline and placed in a warming chamber until they are sternally recumbent. They are then returned to the vivarium and housed under standard conditions until the time of tissue collection. At the time of sacrifice, the mice are anesthetized, the heart is arrested in diastole with KCl or BDM, rinsed with saline, and immersed in fixative. Subsequently, routine procedures for processing, embedding, sectioning, and histological staining are performed. 
Nonsurgical intubation of a mouse and the microsurgical manipulations described make this a technically challenging model to learn and achieve reproducibility. These procedures, combined with the difficulty in performing consistent manipulations of the ligature for timed occlusion(s) and reperfusion or intramyocardial injections, can also affect the survival rate so optimization and consistency are critical.

Numerous genetic manipulations and/or intramyocardial injections of genes, proteins, cells, and/or biomaterials are superimposed upon the dimension of time in studies of acute ischemia/ reperfusion injury and chronic remodeling in mice. This video illustrates the microsurgical procedures for ischemia/reperfusion, permanent coronary artery ligation, and intramyocardial injection studies.

Mouse models are a valuable tool for studying acute injury and chronic remodeling of the myocardium in vivo.  With the advent of genetic modifications to ...

Delivery of Therapeutic Agents Through Intracerebroventricular (ICV) and Intravenous (IV) Injection in Mice

Despite the protective role that blood brain barrier plays in shielding the brain, it limits the access to the central nervous system (CNS) which most often results in failure of potential therapeutics designed for neurodegenerative disorders 1,2. Neurodegenerative diseases such as Spinal Muscular Atrophy (SMA), in which the lower motor neurons are affected, can benefit greatly from introducing the therapeutic agents into the CNS. The purpose of this video is to demonstrate two different injection paradigms to deliver therapeutic materials into neonatal mice soon after birth. One of these methods is injecting directly into cerebral lateral ventricles (Intracerebroventricular) which results in delivery of materials into the CNS through the cerebrospinal fluid 3,4. The second method is a temporal vein injection (intravenous) that can introduce different therapeutics into the circulatory system, leading to systemic delivery including the CNS 5. Widespread transduction of the CNS is achievable if an appropriate viral vector and viral serotype is utilized. Visualization and utilization of the temporal vein for injection is feasible up to postnatal day 6. However, if the delivered material is intended to reach the CNS, these injections should take place while the blood brain barrier is more permeable due to its immature status, preferably prior to postnatal day 2. The fully developed blood brain barrier greatly limits the effectiveness of intravenous delivery. Both delivery systems are simple and effective once the surgical aptitude is achieved. They do not require any extensive surgical devices and can be performed by a single person. However, these techniques are not without challenges. The small size of postnatal day 2 pups and the subsequent small target areas can make the injections difficult to perform and initially challenging to replicate.

Delivery of Therapeutic Agents Through Intracerebroventricular ICV and Intravenous IV Injection in Mice

This article demonstrates two very different methods of injection: 1) into the brain (intracerebroventricular) and 2) systemic (intravenous) to introduce the therapeutic agents into the central nervous system of neonatal mice.

Despite the protective role that blood brain barrier plays in shielding the brain, it limits the access to the central nervous system (CNS) which most ...

Modeling Intracerebral Hemorrhage in Mice: Injection of Autologous Blood or Bacterial Collagenase

Spontaneous intracerebral hemorrhage (ICH) defines a potentially life-threatening neurological malady that accounts for 10-15% of all stroke-related hospitalizations and for which no effective treatments are available to date1,2. Because of the heterogeneity of ICH in humans, various preclinical models are needed to thoroughly explore prospective therapeutic strategies3. Experimental ICH is commonly induced in rodents by intraparenchymal injection of either autologous blood or bacterial collagenase4. The appropriate model is selected based on the pathophysiology of hemorrhage induction and injury progression. The blood injection model mimics a rapidly progressing hemorrhage. Alternatively, bacterial collagenase enzymatically disrupts the basal lamina of brain capillaries, causing an active bleed that generally evolves over several hours5. Resultant perihematomal edema and neurofunctional deficits can be quantified from both models. In this study, we described and evaluated a modified double injection model of autologous whole blood6 as well as an ICH injection model of bacterial collagenase7, both of which target the basal ganglia (corpus striatum) of male CD-1 mice. We assessed neurofunctional deficits and brain edema at 24 and 72 hr after ICH induction. Intrastriatal injection of autologous blood (30 &mu;l) or bacterial collagenase (0.075U) caused reproducible neurofunctional deficits in mice and significantly increased brain edema at 24 and 72 hr after surgery (p&lt;0.05). In conclusion, both models yield consistent hemorrhagic infarcts and represent basic methods for preclinical ICH research.

Clinically relevant animal models of intracerebral hemorrhage (ICH) are needed to extend our knowledge of hemorrhagic stroke and to examine novel therapeutic strategies. In this study, we describe and evaluate two ICH models that implement unilateral injections of either autologous whole blood or bacterial collagenase into the basal ganglia (corpus striatum) of mice.

Spontaneous intracerebral hemorrhage (ICH) defines a potentially life-threatening neurological malady that accounts for 10-15% of all stroke-related ...

Intramyocardial Cell Delivery: Observations in Murine Hearts

Previous studies showed that cell delivery promotes cardiac function amelioration by release of cytokines and factors that increase cardiac tissue revascularization and cell survival. In addition, further observations revealed that specific stem cells, such as cardiac stem cells, mesenchymal stem cells and cardiospheres have the ability to integrate within the surrounding myocardium by differentiating into cardiomyocytes, smooth muscle cells and endothelial cells.
Here, we present the materials and methods to reliably deliver noncontractile cells into the left ventricular wall of immunodepleted mice. The salient steps of this microsurgical procedure involve anesthesia and analgesia injection, intratracheal intubation, incision to open the chest and expose the heart and delivery of cells by a sterile 30-gauge needle and a precision microliter syringe.
Tissue processing consisting of heart harvesting, embedding, sectioning and histological staining showed that intramyocardial cell injection produced a small damage in the epicardial area, as well as in the ventricular wall. Noncontractile cells were retained into the myocardial wall of immunocompromised mice and were surrounded by a layer of fibrotic tissue, likely to protect from cardiac pressure and mechanical load.

Intramyocardial cell delivery in murine models of cardiovascular diseases, such as hypertension or myocardial infarction, is widely used to test the therapeutic potential of different cell types in regenerative studies. Therefore, a detailed description and a clear visualization of this surgical procedure will help to define the limits and advantages of cardiovascular cell therapeutic analyses in small rodents.

Previous studies showed that cell delivery promotes cardiac function amelioration by release of cytokines and factors that increase cardiac tissue ...

Substernal Thyroid Biopsy Using Endobronchial Ultrasound-guided Transbronchial Needle Aspiration

Substernal thyroid goiter (STG) represents about 5.8% of all mediastinal lesions1. There is a wide variation in the published incidence rates due to the lack of a standardized definition for STG. Biopsy is often required to differentiate benign from malignant lesions. Unlike cervical thyroid, the overlying sternum precludes ultrasound-guided percutaneous fine needle aspiration of STG. Consequently, surgical mediastinoscopy is performed in the majority of cases, causing significant procedure related morbidity and cost to healthcare. Endobronchial Ultrasound-guided Transbronchial Needle Aspiration (EBUS-TBNA) is a frequently used procedure for diagnosis and staging of non-small cell lung cancer (NSCLC). Minimally invasive needle biopsy for lesions adjacent to the airways can be performed under real-time ultrasound guidance using EBUS. Its safety and efficacy is well established with over 90% sensitivity and specificity. The ability to perform EBUS as an outpatient procedure with same-day discharges offers distinct morbidity and financial advantages over surgery. As physicians performing EBUS gained procedural expertise, they have attempted to diversify its role in the diagnosis of non-lymph node thoracic pathologies. We propose here a role for EBUS-TBNA in the diagnosis of substernal thyroid lesions, along with a step-by-step protocol for the procedure.

Substernal thyroid lesions are common, and need to be differentiated from malignancy. Obtaining percutaneous fine needle biopsy is not possible due to its retrosternal location. This article proposes a protocol for biopsy of substernal thyroid lesions using Endobronchial Ultrasound-guided Transbronchial Needle Aspiration (EBUS-TBNA).

Substernal thyroid goiter (STG) represents about 5.8% of all mediastinal lesions1. There is a wide variation in the published incidence rates due to the ...

Ultrasound-guided Botulinum Toxin-A Injections: A Method of Treating Sialorrhea

Neurological diseases can be complicated by sialorrhea, an excessive flow of saliva. Patients suffering from moderate to severe sialorrhea have an impaired quality of life, often worsened by correlated complications such as aspiration pneumonia, oral infections, dental caries, and maceration of the skin. Diverse therapeutic approaches have been proposed for the treatment of sialorrhea, including surgery and the use of anticholinergic agents, with limited results and the possible occurrence of serious adverse events. Recently, botulinum toxin (BoNT) injection within the major salivary glands has been proposed in patients refractory to anticholinergic therapy, with the aim of inhibiting local acetylcholine release and gland activity. 
In order to obtain a better outcome in terms of reduction of saliva production, efficacy, duration, and avoidance of major adverse events, we developed an ultrasound-guided BoNT-type A injection technique accurately described in the text. Here we present a method of treating sialorrhea with bilateral parotid and submandibular gland BoNT-type A injections under ultrasound guidance. Four quadrants of the parotid gland and two quadrants of the submandibular gland are visualized and injected using two accesses and one access, respectively. 
The ultrasound-guided procedure provides a simple, non-invasive, real-time visualization of the muscular and glandular tissues and their surrounding structures, optimizing treatment efficacy and safety.

Botulinum toxin is injected into the salivary glands for the treatment of sialorrhea. The ultrasound-guided botulinum toxin injection in both the parotid and submandibular glands demonstrates a sustained efficacy and the absence of serious side effects.

Neurological diseases can be complicated by sialorrhea, an excessive flow of saliva. Patients suffering from moderate to severe sialorrhea have an ...

Ultrasound-guided Intracardiac Injection of Human Mesenchymal Stem Cells to Increase Homing to the Intestine for Use in Murine Models of Experimental Inflammatory Bowel Diseases

Crohn&#39;s disease (CD) is a common chronic inflammatory disease of the small and large intestines. Murine and human mesenchymal stem cells (MSCs) have immunosuppressive potential and have been shown to suppress inflammation in mouse models of intestinal inflammation, even though the route of administration can limit their homing and effectiveness 1,3,4,5. Local application of MSCs to colonic injury models has shown greater efficacy at ameliorating inflammation in the colon. However, there is paucity of data on techniques to enhance the localization of human bone marrow-derived MSCs (hMSCs) to the small intestine, the site of inflammation in the SAMP-1/YitFc (SAMP) model of experimental Crohn&#39;s disease. This work describes a novel technique for the ultrasound-guided intracardiac injection of hMSCs in SAMP mice, a well-characterized spontaneous model of chronic intestinal inflammation. Sex- and age-matched, inflammation-free AKR/J (AKR) mice were used as controls. To analyze the biodistribution and the localization, hMSCs were transduced with a lentivirus containing a triple reporter. The triple reporter consisted of firefly luciferase (fl), for bioluminescent imaging; monomeric red fluorescent protein (mrfp), for cell sorting; and truncated herpes simplex virus thymidine kinase (ttk), for positron emission tomography (PET) imaging. The results of this study show that 24 h after the intracardiac administration, hMSCs localize in the small intestine of SAMP mice as opposed to inflammation-free AKR mice. This novel, ultrasound-guided injection of hMSCs in the left ventricle of SAMP mice ensures a high success rate of cell delivery, allowing for the rapid recovery of mice with minimal morbidity and mortality. This technique could be a useful method for the enhanced localization of MSCs in other models of small-intestinal inflammation, such as TNF&#916;RE6. Future studies will determine if the increased localization of hMSCs by intra-arterial delivery can lead to increased therapeutic efficacy.

Murine studies in models of colonic inflammation have demonstrated that a small percentage (1 - 5%) of mesenchymal stem cells (MSC) injected intravenously or intraperitoneally home to the inflamed colon1,2. This study shows that ultrasound-guided intracardiac injections of MSCs result in increased localization to the intestine.

Crohn&#39;s disease (CD) is a common chronic inflammatory disease of the small and large intestines. Murine and human mesenchymal stem cells (MSCs) have ...

Percutaneous Contrast Echocardiography-guided Intramyocardial Injection and Cell Delivery in a Large Preclinical Model

Cell and gene therapy are exciting and promising strategies for the purpose of cardiac regeneration in the setting of heart failure with reduced ejection fraction (HFrEF). Before they can be considered for use, and implemented in humans, extensive preclinical studies are required in large animal models to evaluate the safety, efficacy, and fate of the injectate (e.g., stem cells) once delivered into the myocardium. Small rodent models offer advantages (e.g., cost effectiveness, amenability for genetic manipulation); however, given inherent limitations of these models, the findings in these rarely translate into the clinic. Conversely, large animal models such as rabbits, have advantages (e.g., similar cardiac electrophysiology compared to humans and other large animals), whilst retaining a good cost-effective balance. Here, we demonstrate how to perform a percutaneous contrast echocardiography-guided intramyocardial injection (IMI) technique, which is minimally invasive, safe, well tolerated, and very effective in the targeted delivery of injectates, including cells, into several locations within the myocardium of a rabbit model. For the implementation of this technique, we also have taken advantage of a widely available clinical echocardiography system. After putting in practice the protocol described here, a researcher with basic ultrasound knowledge will become competent in the performance of this versatile and minimally invasive technique for routine use in experiments, aimed at hypothesis testing of the capabilities of cardiac regenerative therapeutics in the rabbit model. Once competency is achieved, the whole procedure can be performed within 25 min after anaesthetizing the rabbit.

Novel therapeutic strategies in cardiac regenerative medicine require extensive and detailed studies in large preclinical animal models before they can be considered for use in humans. Here, we demonstrate a percutaneous contrast echocardiography-guided intramyocardial injection technique in rabbits, which is valuable for hypothesis testing the efficacy of such novel therapies.

Cell and gene therapy are exciting and promising strategies for the purpose of cardiac regeneration in the setting of heart failure with reduced ejection ...

Transthoracic Echocardiographic Examination in the Rabbit Model

Large animal models such as the rabbit are valuable for translational preclinical research. Rabbits have a similar cardiac electrophysiology compared to that of humans and that of other large animal models such as dogs and pigs. However, the rabbit model has the additional advantage of lower maintenance costs compared to other large animal models. The longitudinal evaluation of cardiac function using echocardiography, when appropriately implemented, is a useful methodology for preclinical assessment of novel therapies for heart failure with reduced ejection fraction (e.g. cardiac regeneration). The correct use of this non-invasive tool requires the implementation of a standardized examination protocol following international guidelines. Here we describe, step by step, a detailed protocol supervised by veterinary cardiologists for performing echocardiography in the rabbit model, and demonstrate how to correctly obtain the different echocardiographic views and imaging planes, as well as the different imaging modes available in a clinical echocardiography system routinely used in human and veterinary patients.

Here we describe, step by step, a detailed protocol for performing echocardiography in the rabbit model. We show how to correctly obtain the different echocardiographic views and imaging planes, as well as the different imaging modes available in a clinical echocardiography system routinely used in human and veterinary patients.

Large animal models such as the rabbit are valuable for translational preclinical research. Rabbits have a similar cardiac electrophysiology compared to ...