Name: contrast imaging in mouse embryos using high-frequency ultrasound
Uploaded: 2015-03-04T14:00:00
Description: Watch this Scientific Journal Video about Contrast Imaging in Mouse Embryos Using High-frequency Ultrasound at JoVE.com

This work was supported by the Terry Fox Program of the National Cancer Institute of Canada.

NOTE: The experimental procedures performed in this study were approved by the Animal Care Committee at Sunnybrook Research Institute (Toronto, Ontario, Canada). Procedures for the humane treatment of animals must be observed at all times. It is assumed that the investigator is trained in the basic operation of an ultrasound imaging system. This protocol works best with two people.
1. Animal Models
<ol>
	<li>Mate CD-1 male and female Mus musculus to obtain wild type embryos for perf...

<ol>
	<li>Voigt, J. 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Ultrasound contrast agents were injected into late-stage gestation mouse embryos and nonlinear contrast images were acquired to measure perfusion parameters and targeted microbubble binding. Successful imaging of microbubbles within embryonic vasculature was dependent on a number of factors, the first being embryo viability. All equipment and apparatus were prepared in advance in order to minimize the time required for isolation of embryos from the uterus to the start of injection. Since the effects of single or repeated...

Contrast-enhanced ultrasound imaging makes use of microbubble contrast agents to visualize and characterize the vascular environment. These agents enable noninvasive assessment of the microcirculation, vascularity and cardiovascular function. In addition, modification of the bubble surface can result in targeted microbubble binding to endothelial biomarkers, as demonstrated in preclinical applications of angiogenesis, atherosclerosis and inflammation 1,2 making molecular ultrasound imaging of vascular events possible. Contrast enhanced ultrasound can therefore be used to identify the complex and diverse environments that influence healthy and diseased vascular states3-5.
In the past number of years, interest in the utility of microbubble imaging has extended to the versatile mouse embryo model. As a model of mammalian development, introduction of microbubbles into the embryonic vasculature enhances physiological study of the developing circulatory system (e.g., blood flow, cardiac output) and in cases of transgenic and targeted mutant mouse models of cardiac disease 6,7, may yield insights into how genetic factors alter cardiovascular function. In fact, quantitative and qualitative 2D analyses of embryonic brain vasculature have already been achieved8. Furthermore, the mouse embryo presents as an excellent model for examining the binding of targeted microbubbles to vascular markers in vivo. Bartelle et al.9, for instance, have introduced avidin microbubbles into embryo cardiac ventricles to assess targeted binding in Biotag-BirA transgenic embryos and examine vascular anatomy. The generation of heterozygous and homozygous mouse models can be also be used as a surrogate for tumor model studies aiming to define the quantitative nature of molecular ultrasound - an important benchmark in translating this technique to the clinic.
Microbubbles are most frequently introduced to the embryonic circulation via intra-cardiac injections into single embryos exposed through a laparotomy8-10. In utero injections, however, face a number of challenges. These include injection guidance, the need to counter motion in the mother and exteriorized embryo, maintenance of hemodynamic viability in the mother and exteriorized embryos, addressing long-term effects of anesthesia and complications due to bleeding11. Therefore, the goal of the investigation was to develop a technique for injecting microbubbles into isolated living late-stage embryos12. This option offers more freedom in terms of injection control and positioning, reproducibility of the imaging plane without obstruction, and simplified image analysis and quantification.
In the present study, we outline a novel procedure for the injection of microbubbles into living murine embryos for the purposes of studying microbubble kinetic behavior and of studying targeted microbubble binding to endogenous endothelial surface markers. Non-linear contrast specific ultrasound imaging is used to measure of a number of basic perfusion parameters including peak enhancement (PE), wash-in rate and time to peak (TTP) in isolated E17.5 embryos. We also demonstrate the validity of the embryo model for assessing the quantitative nature of molecular ultrasound in an embryonic endoglin loss of function transgenic mouse model, where endoglin is a clinically relevant target due to its high expression in vascular endothelial cells at sites of active angiogenesis13. The adhesion of endoglin-targeted (MBE), rat isotype IgG2 control (MBC) and untargeted (MBU) microbubbles is evaluated in heterozygous endoglin (Eng+/-) and homozygous endoglin (Eng+/+) expressing embryos. Analysis of the targeted binding reveals that molecular ultrasound is capable of differentiating between endoglin genotypes and relating receptor densities to quantifiable molecular ultrasound levels.

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			<td height="20" style="height:20px;width:419px;">Reagents</td>
			<td style="width:215px;">Company</td>
			<td style="width:207px;">Catalog Number</td>
			<td style="width:639px;">Comments/Description</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:419px;"></td>
			<td style="width:215px;"></td>
			<td style="width:207px;"></td>
			<td></td>
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			<td height="19" style="height:19px;">Antibodies (biotinylated, eBioscience)</td>
			<td style="width:215px;"></td>
			<td style="width:207px;"></td>
			<td>Antibody choice depends on the experiment</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">&#160;&#160;&#160;&#160;&#160; rat isotype IgG2 control</td>
			<td style="width:215px;">eBioscience</td>
			<td style="width:207px;">13-4321-85</td>
			<td>This antibody/microbubble combination is often required as experimental control&#160;</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">&#160;&#160;&#160;&#160;&#160; biotin anti-mouse CD309</td>
			<td style="width:215px;">eBioscience</td>
			<td style="width:207px;">13-5821-85</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Biotinylated rat MJ 7/18 antibody to mouse endoglin</td>
			<td style="width:215px;">In house hybridoma</td>
			<td style="width:207px;"></td>
			<td>Outside antibodies may also be appropriate: we&#160; have used eBioscience (13-1051-85 ) in the past</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Distilled water</td>
			<td style="width:215px;"></td>
			<td style="width:207px;"></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Embryo media</td>
			<td style="width:215px;"></td>
			<td style="width:207px;"></td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">&#160;&#160;&#160;&#160; 500 mL Dulbecco&#8217;s Modified Eagle&#8217;s Medium with high glucose</td>
			<td>Sigma</td>
			<td>D5796</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">&#160;&#160;&#160;&#160; 50 mL Fetal Bovine Serum</td>
			<td>ATCC</td>
			<td style="width:207px;">30-2020</td>
			<td>lot # 7592456</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">&#160;&#160;&#160;&#160; Hepes&#160;</td>
			<td style="width:215px;">Gibco</td>
			<td style="width:207px;">15630</td>
			<td>5mL, 1M</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">&#160;&#160;&#160;&#160; Penicillin-Streptomycin&#160;</td>
			<td style="width:215px;">Gibco</td>
			<td style="width:207px;">15140-122</td>
			<td>5 mL, 10,000 units Pen., 10,000 ug Strep</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Ethanol, 70%</td>
			<td style="width:215px;"></td>
			<td style="width:207px;"></td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Ice</td>
			<td style="width:215px;"></td>
			<td style="width:207px;"></td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Paraformaldehyde</td>
			<td style="width:215px;">Sigma</td>
			<td style="width:207px;">76240</td>
			<td>4%</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Phosphate Buffered Saline [1x]&#160;</td>
			<td style="width:215px;">Sigma</td>
			<td style="width:207px;">D8537</td>
			<td>1x, w/o calcium chloride &#38; magnesium chloride</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Pregnant mouse, CD-1</td>
			<td style="width:215px;">Charles River Laboratories Inc.&#160;</td>
			<td style="width:207px;"></td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">0.9% sodium chloride (saline)</td>
			<td style="width:215px;">Hospira</td>
			<td style="width:207px;">0409-7984-11</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Ultrasound contrast agent, target ready and untargeted</td>
			<td style="width:215px;">MicroMarker; VisualSonics Inc.</td>
			<td style="width:207px;"></td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Ultrasound gel (Aquasonic 100, colourless)</td>
			<td style="width:215px;">CSP Medical</td>
			<td style="width:207px;">133-1009</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;"></td>
			<td style="width:215px;"></td>
			<td style="width:207px;"></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Equipment</td>
			<td style="width:215px;"></td>
			<td style="width:207px;"></td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;"></td>
			<td style="width:215px;"></td>
			<td style="width:207px;"></td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Cell culture plates (4) :&#160; 100x20 mm</td>
			<td style="width:215px;">Fisher Scientific</td>
			<td style="width:207px;">08-772-22</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Cell culture plates (12) : 60x15 mm</td>
			<td style="width:215px;">Sigma</td>
			<td style="width:207px;">D8054</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:419px;">Centrifuge</td>
			<td>Sorvall Legend RT centrifuge&#160;</td>
			<td style="width:207px;"></td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Conical tubes, 50 mL BD Falcon</td>
			<td style="width:215px;">VWR</td>
			<td style="width:207px;">21008-938</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Diluent</td>
			<td style="width:215px;">Beckman Coulter</td>
			<td style="width:207px;">Isoton II Diluent, 8448011</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Dissection scissors (Wagner)</td>
			<td style="width:215px;">Fine Science Tools</td>
			<td style="width:207px;">Wagner 14068-12</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Forceps (2), Dumont SS (0.10x0.06 mm)</td>
			<td style="width:215px;">Fine Science Tools</td>
			<td style="width:207px;">11200-33</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Forceps, splinter</td>
			<td style="width:215px;">VWR</td>
			<td style="width:207px;">25601-134</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Glass beaker, 2 L (Griffin Beaker)</td>
			<td style="width:215px;">VWR</td>
			<td style="width:207px;">89000-216</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Glass capillaries, 1x90 mm GD-1 with filament</td>
			<td style="width:215px;">Narishige</td>
			<td style="width:207px;">GD-1</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Glass needle puller</td>
			<td style="width:215px;">Narishige</td>
			<td style="width:207px;">PN-30</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Gloves</td>
			<td style="width:215px;">Ansell</td>
			<td style="width:207px;">4002</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Gross anatomy probe</td>
			<td style="width:215px;">Fine Science Tools</td>
			<td style="width:207px;">10088-15</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Hot plate</td>
			<td style="width:215px;">VWR</td>
			<td style="width:207px;">89090-994</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Ice bucket</td>
			<td style="width:215px;">Cole Parmer</td>
			<td style="width:207px;">RK 06274-01</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Imaging Platform</td>
			<td style="width:215px;">VisualSonics Inc.</td>
			<td style="width:207px;">Integrated Rail System</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Light source, fiber-optic</td>
			<td style="width:215px;">Fisher Scientific</td>
			<td style="width:207px;">12-562-36</td>
			<td>Ideally has adjustable arms</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Luers (12), polypropylene barbed female &#188;-28 UNF thread</td>
			<td style="width:215px;">Cole Parmer</td>
			<td style="width:207px;">45500-30</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Micro-ultrasound system, high-frequency</td>
			<td style="width:215px;">VisualSonics Inc.</td>
			<td style="width:207px;">Vevo2100</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Needles, 21 gauge&#160; (1&#8221;)</td>
			<td style="width:215px;">VWR</td>
			<td style="width:207px;">305165</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Particle size analyzer</td>
			<td style="width:215px;">Beckman Coulter</td>
			<td style="width:207px;">Multisizer 3 Coulter Counter</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Perforated spoon (Moria)</td>
			<td style="width:215px;">Fine Science Tools</td>
			<td style="width:207px;">MC 17 10373-17</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Pins (6), black anodized minutien 0.15 mm</td>
			<td style="width:215px;">Fine Science Tools</td>
			<td style="width:207px;">26002-15</td>
			<td></td>
		</tr>
		<tr height="57">
			<td height="57" style="height:57px;">Pipettors [2-20 uL, 20-200uL, 100-1000uL]</td>
			<td style="width:215px;">Eppendorf</td>
			<td style="width:207px;">Research Plus&#160; adjustable 3120000038;&#160;&#160;&#160;&#160;&#160;&#160; 3120000054;&#160;&#160;&#160;&#160;&#160;&#160; 3120000062</td>
			<td style="width:639px;"></td>
		</tr>
		<tr height="38">
			<td height="38" style="height:38px;">Pipettor tips [2-200uL, 50-1000uL]</td>
			<td style="width:215px;">Eppendorf</td>
			<td style="width:207px;">epT.I.P.S.&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; 22491334;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; 022491351</td>
			<td style="width:639px;"></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Scissors</td>
			<td style="width:215px;"></td>
			<td style="width:207px;"></td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Sylgard 184 Silicone Elastomer Kit</td>
			<td style="width:215px;">Dow Corning</td>
			<td style="width:207px;"></td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Tubing, Tygon laboratory 1/32x3/32&#8221;</td>
			<td style="width:215px;">VWR</td>
			<td style="width:207px;">63010-007</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Wooden applicator stick (swab, cotton head)</td>
			<td style="width:215px;">VWR</td>
			<td style="width:207px;">CA89031-270</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Surgical microscope 5-8x magnification</td>
			<td style="width:215px;">Fisher Scientific</td>
			<td style="width:207px;">Steromaster</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Syringes, 1 mL Normject</td>
			<td style="width:215px;">Fisher</td>
			<td style="width:207px;">14-817-25</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Syringes (10), 30 mL</td>
			<td style="width:215px;">VWR</td>
			<td style="width:207px;">CA64000-041</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Syringe infusion pump&#160;</td>
			<td style="width:215px;">Bio-lynx&#160;</td>
			<td style="width:207px;">NE-1000</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;">Thermometer, -20-110oC</td>
			<td style="width:215px;">VWR</td>
			<td style="width:207px;">89095-598</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Timer</td>
			<td style="width:215px;">VWR</td>
			<td style="width:207px;">33501-418</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Tubes, Eppendorf</td>
			<td style="width:215px;">VWR</td>
			<td style="width:207px;">20170-577</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Tube racks (3)</td>
			<td style="width:215px;">VWR</td>
			<td style="width:207px;">82024-462</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Ultrasound transducer, 20 MHz</td>
			<td style="width:215px;">VisualSonics Inc.</td>
			<td style="width:207px;">MS250</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Vannas-Tubingen, angled up</td>
			<td style="width:215px;">Fine Science Tools</td>
			<td style="width:207px;">15005-08</td>
			<td></td>
		</tr>
	</tbody>
</table>

contrast imaging in mouse embryos using high-frequency ultrasound

Ultrasound contrast-enhanced imaging can convey essential quantitative information regarding tissue vascularity and perfusion and, in targeted applications, facilitate the detection and measure of vascular biomarkers at the molecular level. Within the mouse embryo, this noninvasive technique may be used to uncover basic mechanisms underlying vascular development in the early mouse circulatory system and in genetic models of cardiovascular disease. The mouse embryo also presents as an excellent model for studying the adhesion of microbubbles to angiogenic targets (including vascular endothelial growth factor receptor 2 (VEGFR2) or &#945;v&#946;3) and for assessing the quantitative nature of molecular ultrasound. We therefore developed a method to introduce ultrasound contrast agents into the vasculature of living, isolated embryos. This allows freedom in terms of injection control and positioning, reproducibility of the imaging plane without obstruction and motion, and simplified image analysis and quantification. Late gestational stage (embryonic day (E)16.6 and E17.5) murine embryos were isolated from the uterus, gently exteriorized from the yolk sac and microbubble contrast agents were injected into veins accessible on the chorionic surface of the placental disc. Nonlinear contrast ultrasound imaging was then employed to collect a number of basic perfusion parameters (peak enhancement, wash-in rate and time to peak) and quantify targeted microbubble binding in an endoglin mouse model. We show the successful circulation of microbubbles within living embryos and the utility of this approach in characterizing embryonic vasculature and microbubble behavior.

The injection of ultrasound contrast agents into ex utero mouse embryos is dependent on the successful isolation of living, late-gestational stage embryos from the uterus and maintenance of viability over the course of the injection and related ultrasound imaging. Once the embryo has been exteriorized and positioned, as shown in Figure 1, careful injection of contrast agent into the embryonic vasculature is possible. A typical B-mode ultrasound image of an E17.5 mouse embryo is shown in ...

Watch this Scientific Journal Video about Contrast Imaging in Mouse Embryos Using High-frequency Ultrasound at JoVE.com

Contrast Imaging in Mouse Embryos Using High-frequency Ultrasound

Here, we present a protocol to inject ultrasound microbubble contrast agents into living, isolated late-gestation stage murine embryos. This method enables the study of perfusion parameters and of vascular molecular markers within the embryo using contrast-enhanced high-frequency ultrasound imaging.

Ultrasound contrast-enhanced imaging can convey essential quantitative information regarding tissue vascularity and perfusion and, in targeted ...

Research

JoVE Journal

Developmental Biology

Analyzing In Vivo Cell Migration using Cell Transplantations and Time-lapse Imaging in Zebrafish Embryos

Analyzing In Vivo Cell Migration using Cell Transplantations and Time-lapse Imaging in Zebrafish Embryos

Cell migration is key to many physiological and pathological conditions, including cancer metastasis. The cellular and molecular bases of cell migration ...

Live Imaging of Mouse Secondary Palate Fusion

The fusion of the secondary palatal shelves to form the intact secondary palate is a key process in mammalian development and its disruption can lead to ...

A Novel Use of Three-dimensional High-frequency Ultrasonography for Early Pregnancy Characterization in the Mouse

High-frequency ultrasonography (HFUS) is a common method to non-invasively monitor the real-time development of the human fetus in utero. The mouse is ...

Fetal Mouse Cardiovascular Imaging Using a High-frequency Ultrasound (30/45MHZ) System

Fetal Mouse Cardiovascular Imaging Using a High-frequency Ultrasound 30/45MHZ System

Congenital heart defects (CHDs) are the most common cause of childhood morbidity and early mortality. Prenatal detection&#160;of the underlying molecular ...

Visualizing the Node and Notochordal Plate In Gastrulating Mouse Embryos Using Scanning Electron Microscopy and Whole Mount Immunofluorescence

The post-implantation mouse embryo undergoes major shape changes after the initiation of gastrulation and morphogenesis. A hallmark of morphogenesis is ...

High Frequency Ultrasound for the Analysis of Fetal and Placental Development In Vivo

High Frequency Ultrasound for the Analysis of Fetal and Placental Development In Vivo

Ultrasound imaging is a widespread method used to detect organ anomalies and tumors in human and animal tissues. The method is non-invasive, harmless, and ...

Analysis of Congenital Heart Defects in Mouse Embryos Using Qualitative and Quantitative Histological Methods

Congenital heart defects (CHD) are the most common type of birth defect in humans, affecting up to 1% of all live births. However, the underlying causes ...

High-Frequency Ultrasound Echocardiography to Assess Zebrafish Cardiac Function

The zebrafish (Danio rerio) has become a very popular model organism in cardiovascular research, including human cardiac diseases, largely due to its ...

Imaging Intranuclear Actin Rods in Live Heat Stressed Drosophila Embryos

Imaging Intranuclear Actin Rods in Live Heat Stressed Drosophila Embryos

The purpose of this protocol is to visualize intranuclear actin rods that assemble in live Drosophila melanogaster embryos following heat stress. Actin ...

Is My Mouse Pregnant? High-Frequency Ultrasound Assessment

The mouse is the mammalian animal model of choice for many human diseases and biological processes. Developmental biology often requires staged-pregnant ...