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 s...

<ol>
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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

Research

JoVE Journal

Medicine

14.6K visualizações.  Boston Children's Hospital.  Injeção intramiocárdica percutânea guiada por ecocardiografia representa uma modalidade eficiente, confiável e targetable para a entrega de agentes de transferência de genes ou células no coração murino. Seguindo os passos descritos neste protocolo, o operador pode rapidamente tornar-se competente nessa técnica versátil, minimamente invasiva. 