Name: using in vivo and tissue and cell explant approaches to study the morphogenesis and pathogenesis of the embryonic and perinatal aorta
Uploaded: 2017-09-12T12:30:00
Description: Watch this Scientific Journal Video about Using In Vivo and Tissue and Cell Explant Approaches to Study the Morphogenesis and Pathogenesis of the Embryonic and Perinatal Aorta at JoVE.com

We thank Dean Li for sharing his laboratory's protocol for aortic SMC isolation. Funding support was provided by the National Institutes of Health (R21NS088854, R01HL125815, and R01HL133016 to D.M.G), the American Heart Association (Grant-in-Aid 14GRNT19990019 to D.M.G.), and Yale University (Brown-Coxe Fellowship to A.M. and startup funds to D.M.G.).

All mouse protocols are approved by the Institutional Animal Care and Use Committee at Yale University.
1. In Vivo Embryonic Fate Mapping and Clonal Analysis
Note: We have used these approaches widely to evaluate the origins of cells and their clonal architecture in development and disease models7,8,9,10.
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	<li>Set up mating...

<ol>
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In contrast to the extensive investigations of the murine aorta and its major branches in adult pathological conditions, such as models of atherosclerosis, less is known regarding the morphogenesis and the pathogenesis of the embryonic and perinatal aorta. Here, we focus on the embryonic/perinatal aorta, specifically the SMCs, and provide protocols to study the aorta through in vivo, tissue explant, and SMC isolation approaches. These complimentary approaches provide the investigator with diverse approaches to s...

The circulatory systems of multicellular organisms function to deliver nutrients and oxygen to cells that are not in contact with the external environment and to remove waste products and carbon dioxide from these cells. In vertebrates, the primary circulatory system consists of the heart, which pumps blood through a series of blood vessels. The walls of large blood vessels, such as arteries and veins, consist of three layers: i) the intima, or inner layer of endothelial cells; ii) the media, or middle layer of alternating circumferentially elongated smooth muscle cells SMCs and elastic lamellae; and iii) the adventitia, or outer layer of connective tissue and fibroblasts. The vast majority of studies in vascular biology focus on endothelial cells, investigating the formation of new endothelial cell-lined tubes through angiogenesis. In comparison, SMCs receive relatively little attention. However, SMCs are a critical cell type in the construction of the normal arterial wall and in vascular pathologies.
The aorta is the largest-caliber artery in the body, receiving the cardiac output from the left ventricle of the heart. It is afflicted by diverse human diseases, including atherosclerosis, aneurysm, and dissection. In adult organisms, the aorta and its major branches are intensely studied in models of vascular disease. For instance, high fat diet fed mice that are null for the gene encoding the low-density lipoprotein receptor or apolipoprotein E, develop atherosclerosis, and recent fate mapping studies indicate that pre-existing SMCs give rise to multiple cell types in the atherosclerotic plaque1. In aortic aneurysms, pathological changes include SMC apoptosis and extracellular matrix remodeling2,3.
Substantially less is known regarding SMC morphogenesis and pathogenesis during the embryonic and perinatal periods. Here, we provide protocols for studying embryonic and perinatal aortic SMCs in vivo, in tissue explants and in isolated cells. For instance, the first section of the protocol delineates fate mapping and clonal analysis in embryonic mice. Cre recombinase expressed under the control of a cell-specific promoter facilitates the marking of specific cells and their progeny4,5,6; however, temporal control of cell-specific labeling can be challenging during embryonic development in mice. In this context, with embryos expressing the conditional CreER under a promoter active in SMCs (e.g.,Myh11 or Acta2) and a Cre reporter, we provide methods for injecting tamoxifen or its active metabolite 4-OH-tamoxifen in pregnant dams and for analyzing the labeled cells in embryos or postnatal offspring. Furthermore, in contrast to fate mapping studies, which predominately utilize Cre reporters with a single reporter fluorophore1,7, clonal analysis is substantially enhanced with multi-color Cre reporters.
The second and third sections of protocol describe methods for isolating and culturing embryonic aortic explants and aortic SMCs from neonates, respectively. These approaches allow for the manipulation of signaling pathways, specifically in aortic explants or SMCs, and for analyzing the direct effects of pharmacological agents. Thus, the role of specific genes in the tissue of interest can be screened in a far more rapid fashion than through traditional genetic manipulations in mice. In addition, the isolated SMC studies facilitate the analysis of cell migration and adhesion, which are technically limited in vivo.
Finally, the fourth protocol section delineates the placement of a subcutaneous osmotic mini-pump loaded with pharmacological agents in pregnant (or non-pregnant) mice. This method facilitates the analysis of the effect on embryonic development caused by agents that require continuous infusion because of rapid metabolism. The alternative of frequent injections is not practical for many agents and should be avoided, as it may cause significant discomfort in the pregnant dam.

<table width="1061">
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	<tbody>
		<tr height="21">
			<td height="21" style="width:323px;height:21px;">Tamoxifen</td>
			<td style="width:216px;">Sigma</td>
			<td style="width:111px;">T5648</td>
			<td style="width:412px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:323px;height:21px;">Corn oil</td>
			<td style="width:216px;">Sigma</td>
			<td style="width:111px;">C-8267</td>
			<td>Vehicle for tamoxifen</td>
		</tr>
		<tr height="21">
			<td height="21" style="width:323px;height:21px;">4-OH-tamoxifen</td>
			<td style="width:216px;">Sigma</td>
			<td style="width:111px;">H7904</td>
			<td>Active metabolite of tamoxifen</td>
		</tr>
		<tr height="21">
			<td height="21" style="width:323px;height:21px;">Progesterone</td>
			<td style="width:216px;">Sigma</td>
			<td style="width:111px;">P8783-5G</td>
			<td>Use at half the concentration of tamoxifen</td>
		</tr>
		<tr height="21">
			<td height="21" style="width:323px;height:21px;">OCT compound</td>
			<td style="width:216px;">Sakura tissue tek</td>
			<td style="width:111px;">4583</td>
			<td>For making cryoblocks</td>
		</tr>
		<tr height="21">
			<td height="21" style="width:323px;height:21px;">Cryomolds</td>
			<td style="width:216px;">Polysciences inc</td>
			<td style="width:111px;">18986</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:323px;height:21px;">DAPI</td>
			<td style="width:216px;">Sigma</td>
			<td style="width:111px;">D9542</td>
			<td>IHC staining of nucleus, final concentration 5 mg/ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cy3 directly conjugated anti-SMA antibody</td>
			<td>Sigma</td>
			<td>A2547</td>
			<td>IHC staining of SMA, final dilution 1:500</td>
		</tr>
		<tr height="21">
			<td height="21" style="width:323px;height:21px;">Anti-CD31 antibody</td>
			<td style="width:216px;">BD Pharmingen</td>
			<td style="width:111px;">550274</td>
			<td>IHC staining of GFP, final concentration 0.006 mg/ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="width:323px;height:21px;">Anti-GFP antibody</td>
			<td style="width:216px;">Thermo Fisher Scientific</td>
			<td style="width:111px;">A-11121</td>
			<td>IHC staining of CD31, final concentration 0.0016 mg/ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Secondary antibody goat anti-rabbit, Alexa 647</td>
			<td style="width:216px;">Life Technologies</td>
			<td>a21244</td>
			<td>IHC staining, final concentration 0.004 mg/ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Secondary antibody goat anti-rabbit, Alexa 488</td>
			<td style="width:216px;">Life Technologies</td>
			<td>a11008</td>
			<td>IHC staining, final concentration 0.004 mg/ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="width:323px;height:21px;">DMEM</td>
			<td style="width:216px;">Thermo Fisher Scientific</td>
			<td style="width:111px;">10567-014</td>
			<td>For cell culture</td>
		</tr>
		<tr height="21">
			<td height="21" style="width:323px;height:21px;">FBS</td>
			<td style="width:216px;">Thermo Fisher Scientific</td>
			<td style="width:111px;">10437028</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:323px;height:21px;">Anti-integrin beta3 blocking antibody</td>
			<td style="width:216px;">BD Biosciences</td>
			<td style="width:111px;">553343</td>
			<td>Clone 2C9.G2, final concentration 0.02 mg/ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Collagenase</td>
			<td>Worthington Biochemical Corp</td>
			<td>44H14977A</td>
			<td>For digesting aorta</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Elastase</td>
			<td>Worthington Biochemical Corp</td>
			<td>34K15139</td>
			<td>For digesting aorta</td>
		</tr>
		<tr height="21">
			<td height="21" style="width:323px;height:21px;">Antibiotic-antimycotic (100X)</td>
			<td style="width:216px;">Thermo Fisher Scientific</td>
			<td style="width:111px;">15240062</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:323px;height:21px;">Recombinant human FGF</td>
			<td style="width:216px;">Promega</td>
			<td style="width:111px;">G5071</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:323px;height:21px;">Recombinant human EGF</td>
			<td style="width:216px;">Promega</td>
			<td style="width:111px;">G5021</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:323px;height:21px;">Penicillin/streptomycin (10,000 U/ml)</td>
			<td style="width:216px;">Thermo Fisher Scientific</td>
			<td style="width:111px;">15140122</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:323px;height:21px;">Amphotericin B</td>
			<td style="width:216px;">Thermo Fisher Scientific</td>
			<td style="width:111px;">15290026</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:323px;height:21px;">Tissue culture plates</td>
			<td style="width:216px;">Corning</td>
			<td style="width:111px;">CLS430165</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:323px;height:21px;">Alzet osmotic mini-pump</td>
			<td style="width:216px;">Durect Corporation</td>
			<td style="width:111px;">2001</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ECLIPSE 80i Upright Fluorescent Microscope</td>
			<td style="width:216px;">Nikon </td>
			<td style="width:111px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;"> TCS SP5</td>
			<td style="width:216px;">Leica</td>
			<td style="width:111px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Branson Sonifier 450</td>
			<td style="width:216px;">VWR</td>
			<td style="width:111px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Myh11-CreERT2 mice</td>
			<td style="width:216px;">The Jackson Laboratory </td>
			<td>19079</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Acta2-CreERT2 mice</td>
			<td style="width:216px;"></td>
			<td style="width:111px;"></td>
			<td>Obtained from lab of Dr. Pierre Chambon and Daniel Metzger</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ROSA26R-CreERT2 mice</td>
			<td style="width:216px;">The Jackson Laboratory </td>
			<td style="width:111px;">8463</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ROSA26R(mTmG/mTmG) mice</td>
			<td style="width:216px;">The Jackson Laboratory </td>
			<td> 026862</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ROSA26R(EYFP/EYFP) mice</td>
			<td style="width:216px;">The Jackson Laboratory </td>
			<td> 006148 </td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ROSA26R(Confetti/Confetti) mice</td>
			<td style="width:216px;">The Jackson Laboratory </td>
			<td>13731</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ROSA26R(Rb/Rb) mice</td>
			<td style="width:216px;">Lab of Dr. Irv Weissman</td>
			<td style="width:111px;"></td>
			<td style="width:412px;">Obtained from lab of Dr. Irv Weissman</td>
		</tr>
	</tbody>
</table>

using in vivo and tissue and cell explant approaches to study the morphogenesis and pathogenesis of the embryonic and perinatal aorta

The aorta is the largest artery in the body. The aortic wall is composed of an inner layer of endothelial cells, a middle layer of alternating elastic lamellae and smooth muscle cells (SMCs), and an outer layer of fibroblasts and extracellular matrix. In contrast to the widespread study of pathological models (e.g., atherosclerosis) in the adult aorta, much less is known about the embryonic and perinatal aorta. Here, we focus on SMCs and provide protocols for the analysis of the morphogenesis and pathogenesis of embryonic and perinatal aortic SMCs in normal development and disease. Specifically, the four protocols included are: i) in vivo embryonic fate mapping and clonal analysis; ii) explant embryonic aorta culture; iii) SMC isolation from the perinatal aorta; and iv) subcutaneous osmotic mini-pump placement in pregnant (or non-pregnant) mice. Thus, these approaches facilitate the investigation of the origin(s), fate, and clonal architecture of SMCs in the aorta in vivo. They allow for modulating embryonic aorta morphogenesis in utero by continuous exposure to pharmacological agents. In addition, isolated aortic tissue explants or aortic SMCs can be used to gain insights into the role of specific gene targets during fundamental processes such as muscularization, proliferation, and migration. These hypothesis-generating experiments on isolated SMCs and the explanted aorta can then be assessed in the in vivo context through pharmacological and genetic approaches.

In a representative clonal analysis of SMCs in embryos mutant for Eln (the gene encoding the extracellular matrix protein elastin), Eln(+/-), Acta2-CreERT2 mice were mated to Eln(+/-) mice also carrying the multi-color ROSA26R(Rb/Rb) reporter. As described in step 1, plugs were checked, pregnant dams were induced with a single tamoxifen injection (1.5 mg) at E12.5, and they were sacrificed at E18.5. Embryos were harves...

Watch this Scientific Journal Video about Using In Vivo and Tissue and Cell Explant Approaches to Study the Morphogenesis and Pathogenesis of the Embryonic and Perinatal Aorta at JoVE.com

Using In Vivo and Tissue and Cell Explant Approaches to Study the Morphogenesis and Pathogenesis of the Embryonic and Perinatal Aorta

Protocols for studying the embryonic and perinatal murine aorta using in vivo clonal analysis and fate mapping, aortic explants, and isolated smooth muscle cells are detailed here. These diverse approaches facilitate the investigation of the morphogenesis of the embryonic and perinatal aorta in normal development and the pathogenesis in disease.

Using In Vivo and Tissue and Cell Explant Approaches to Study the Morphogenesis and Pathogenesis of the Embryonic and Perinatal Aorta

The aorta is the largest artery in the body. The aortic wall is composed of an inner layer of endothelial cells, a middle layer of alternating elastic ...

The overall goal of these procedures is to study the formation of the embryonic and perinatal aortic walls during normal development as well as, perturbations in this process during disease. This method can help answer key questions in the vascular development field such as, what is the source of the cells that contribute to the embryonic and perinatal vascular medium. The main advantage of these techniques is that they allow the evaluation of the smooth muscle pathogenesis and morphogenesis that occur during the embryonic and perinatal stages of development.The implication of these techniques stem towards the therapy of vascular diseases such as, supravalvular aortic stenosis of periodic disease that causes excessive sumo cell production. The mini pump placement procedure will be performed by Dr.Jiasheng Zhang, a research scientist directing a microsurgery core and Yale University. Begin by setting up mating pairs between two to six month old mice with Cre ER and mice with a cre reporter.Using a metal probe, check for vaginal plugs each morning, separating the female from the male when a plug is detected. For early embryonic induction, inject tamoxifen intraperitoneally into the pregnant damp. To mark cells in the mid to late gestational period and to trace their fate or clonality in the post-natal mouse, inject progesterone into the intraperitoneal cavity of the pregnant damp incompetently with tamoxifen in a one to two dose ratio.To harvest the embryos on the appropriate embryonic date, cleanse the abdomen of the pregnant damp with 70%ethanol and use scissors to open the abdomen to remove the uterus. Collect the embryos from the uterus using forceps and a stereo microscope to carefully separate them from the placenta and yolk sac. Fix the embryos in 4%paraformaldehyde at four degrees celsius for two hours.Followed by three washes in PBS to remove the excess fixative. After the third wash, incubate the embryos in 30%sucrose in PBS, in individual 15 milliliter tubes until the embryos sink. Next, fill plastic freezing molds with optimum cutting temperature compound up to two thirds of the maximum volume and place one embryo vertically in each mold.After 10 minutes at room temperature, freeze the tissues upright in a dry ice 70%ethanol bath and set the cryostat temperature to 22 degrees celsius. Section the tissue blocks to generate 10 to 20 micrometer thick transverse tissue slices through the entirety of each aorta, capturing each section on a glass microscope slide as they are obtained. When all of the samples have been acquired, dry the slides at room temperature for 30 minutes prior to 80 degree celsius storage.To stain the tissue samples, thaw the slides at room temperature, protect it from light to avoid fluorophore bleaching and wash the slides in 0.1%PBS twin 20. For clonal analysis, stain the tissues with an appropriate nuclear dye and directly image the other flurophores of the rainbow cre reporter on a fluorescent microscope. For fate mapping, with the mTmG cre reporter, visualize the GFP expression by direct imaging with or without immunostaining.To culture and explant an embryonic aorta, place the embryo in the supine position and secure the extended limbs to a dissection board under a stereo microscope. Using scissors, make a vertical incision from the abdomen through the sternum to the upper thorax. Dissect away the finest tracheal lungs, esophagus, liver and intestine.Use forceps to gently pull the heart ventrally, using scissors to dissect the aorta away from the dorsal aspect of the thoracic and abdominal cavities. Cut the aorta at the proximal root and the distal abdominal positions to release it and place the harvested aorta in sterile ice cold PBS in a cell culture hood. After a brief wash, transfer the aorta to one well of a 24 well plate, containing DMEM medium supplemented with 0.5%PBS and place the plate in a cell culture incubator for up to 24 hours.At the end of the incubation, wash the aorta two times with PBS and fix the tissue in 4%paraformaldehyde for 20 minutes. After three more PBS washes, transfer the aorta to a 1.5 milliliter tube containing 30%sucrosine PBS until the tissue sinks. For perinatal aorta smooth muscle cell isolation, use a 23 gauge needle to puncture the left ventricle of a postnatal day 0.5 mouse and use plastic tubing to connect the needle to a sterile PBS containing syringe, held vertically in an elevated position, so the PBS flows into the left ventricle by gravity.When the liver blanches, use forceps to remove the adventitial tissue on the outside of the aorta and harvest the aorta as just demonstrated. Dissociate the aortic tissue in 500 microliters of digestion solution with manual shaking every five to 10 minutes. After 45 minutes, transfer the tube to a sterile cell culture hood and use a 200 microliter pipette to triturate the tissue slurry until a single cell suspension has been obtained.Transfer the cells into a 15 milliliter conical tube and then, add two milliliters of DMEM and collect the cells by centrifugation. Resuspend the pellet in three milliliters of smooth muscle cell culture medium and seed the cells onto a 35 millimeter culture plate. Then, place the plate into a 37 degree celsius incubator, refreshing the cell culture medium every three days.To place a subcutaneous osmotic mini pump, begin by shaving the lower back of an anesthetized mouse with clippers and place the mouse in the prone position on a heated surgical plate. Scrub the back with betadine and isopropyl alcohol and place the mouse under a stereo microscope. Then, use a scalpel to make a 0.5 to one centimeter horizontal skin incision approximately three to five centimeters rostral to the base of the tail, without injuring the underlying muscle.Insert a hemostat into the incision and open and close the hemostat jaws to create a subcutaneous pocket. Insert an osmotic mini pump filled with the agent of interest into the pocket and use 6 o non-absorbable sutures to close the incision. Then, allow the mouse to recover with monitoring until the achievement of sternal recumbency.Embryos mutant for the gene encoding the extracellular matrix protein, elastin accumulate excess smooth muscle cells in the inner layers of the aorta, beginning after embryonic day 15.5. Clonal analysis of the smooth muscle cells with the multicolor cre reporter during this process, indicates that the cells are of multiple colors and thus, are polyclonal. Immunostaining explanted aorta sections reveals that elastin mutant embryonic day 15.5 aortas become hyper muscular and stenodic within 18 hours of culture, a process that is attenuated by the addition of an anti antegrin beta three blocking antibody.Smooth muscle cells isolated from the aorta of wild type mice that post natal day 0.5 express smooth muscle cell markers but not CD31. Continuous infusion of an integrin beta three inhibitor into pregnant damps beginning on embryonic day 13.5, significantly attenuates aortic stenosis and hyper muscularization in mice mutant for the extracellular matrix protein, elastin. But do not alter the aortas of wild type mice.Once mastered, the osmotic mini pump placement technique can be completed in less than 10 minutes if it is performed properly. Following these procedures, these approaches can also be extrapolated to study smooth muscle coded, non-vascular such as, tissue of gastrointestinal tract or the lung areas. After watching this video, you should have a good understanding of how to conduct in-vivo embryonic fit mapping and clonal analysis, culture explanted embryonic aortas, perinatal aortic smooth muscle cells and explant subcutaneous osmotic mini pumps.Don't forget that working with mice, tamoxifen and a fixed reducer can be hazardous and that precautions such as, wearing gloves and a lab coat and taking extra care with should always be taking while performing these procedures.

using-vivo-tissue-cell-explant-approaches-to-study-morphogenesis

Research

JoVE Journal

Developmental Biology

Ex Vivo Culture of Pharyngeal Arches to Study Heart and Muscle Progenitors and Their Niche

The pharyngeal mesoderm of developing embryos contributes to broad regions of head and heart musculature. We have developed a novel method to study head and heart progenitor cell development with pharyngeal arches (also known as branchial arches) ex vivo. Using this method, we have recently described that the second pharyngeal arch contains self-renewing heart progenitors and serves as a microenvironment for expansion of the progenitors during mouse heart development. The progenitor cells remain undifferentiated and expansive inside the arch, but quickly become functional cardiomyocytes as they migrate out of the arch. We also reported that first pharyngeal arch contains muscle progenitors giving rise to myotubes after leaving the arch. Here, we demonstrate the procedure for the dissection and ex vivo culture of first and second pharyngeal arches from developing mouse embryos. The method enables one to study head and heart progenitor/muscle development, including cardiomyocyte and myotube formation in detail ex vivo.

Ex Vivo Culture of Pharyngeal Arches to Study Heart and Muscle Progenitors and Their Niche

Here, we present a protocol to culture pharyngeal arches to study the biology of heart and muscle progenitor cells and their microenvironment.

The pharyngeal mesoderm of developing embryos contributes to broad regions of head and heart musculature. We have developed a novel method to study head ...

Stem cell-like Xenopus Embryonic Explants to Study Early Neural Developmental Features In Vitro and In Vivo

Understanding the genetic programs underlying neural development is an important goal of developmental and stem cell biology. In the amphibian blastula, cells from the roof of the blastocoel are pluripotent. These cells can be isolated, and programmed to generate various tissues through manipulation of genes expression or induction by morphogens. In this manuscript protocols are described for the use of Xenopus laevis blastocoel roof explants as an assay system to investigate key in vivo and in vitro features of early neural development. These protocols allow the investigation of fate acquisition, cell migration behaviors, and cell autonomous and non-autonomous properties. The blastocoel roof explants can be cultured in a serum-free defined medium and grafted into host embryos. This transplantation into an embryo allows the investigation of the long-term lineage commitment, the inductive properties, and the behavior of transplanted cells in vivo. These assays can be exploited to investigate molecular mechanisms, cellular processes and gene regulatory networks underlying neural development. In the context of regenerative medicine, these assays provide a means to generate neural-derived cell types in vitro that could be used in drug screening.

Stem cell-like Xenopus Embryonic Explants to Study Early Neural Developmental Features In Vitro and In Vivo

In Xenopus embryos, cells from the roof of the blastocoel are pluripotent and can be programmed to generate various tissues. Here, we describe protocols to use amphibian blastocoel roof explants as an assay system to investigate key in vivo and in vitro features of early neural development.

Understanding the genetic programs underlying neural development is an important goal of developmental and stem cell biology. In the amphibian blastula, ...

Transcriptome Profiling of In-Vivo Produced Bovine Pre-implantation Embryos Using Two-color Microarray Platform

Early embryonic loss is a large contributor to infertility in cattle. Moreover, bovine becomes an interesting model to study human preimplantation embryo development due to their similar developmental process. Although genetic factors are known to affect early embryonic development, the discovery of such factors has been a serious challenge. Microarray technology allows quantitative measurement and gene expression profiling of transcript levels on a genome-wide basis. One of the main decisions that have to be made when planning a microarray experiment is whether to use a one- or two-color approach. Two-color design increases technical replication, minimizes variability, improves sensitivity and accuracy as well as allows having loop designs, defining the common reference samples. Although microarray is a powerful biological tool, there are potential pitfalls that can attenuate its power. Hence, in this technical paper we demonstrate an optimized protocol for RNA extraction, amplification, labeling, hybridization of the labeled amplified RNA to the array, array scanning and data analysis using the two-color analysis strategy.

Transcriptome Profiling of In-Vivo Produced Bovine Pre-implantation Embryos Using Two-color Microarray Platform

Microarray technology allows quantitative measurement and gene expression profiling of transcripts on a genome-wide basis. Therefore, this protocol provides an optimized technical procedure in a two-color custom made bovine array using Day 7 bovine embryos to demonstrate the feasibility of using low amount of total RNA.

Early embryonic loss is a large contributor to infertility in cattle. Moreover, bovine becomes an interesting model to study human preimplantation embryo ...

Ovarian Tissue Culture to Visualize Phenomena in Mouse Ovary

Mammalian females periodically ovulate an almost constant number of oocytes during each estrus cycle. To sustain such regularity and periodicity, regulation occurs at the hypothalamic-pituitary-gonadal axis level and on developing follicles in the ovary. Despite active studies, follicle development mechanisms are not clear because of the several steps involved from the dormant primordial follicle activation to ovulation, and because of the regulation complexity that differs at each follicular stage. To investigate the mechanisms of follicle development, and the dynamics of follicles throughout the estrus cycle, we developed a mouse ovarian tissue culture model that can be used to observe follicle development using a microscope. Systematic follicle development, periodical ovulation, and follicle atresia can all be reproduced in the cultured ovary model, and the culture conditions can be experimentally modulated. Here, we demonstrate the usefulness of this method in the study of the regulatory mechanisms of follicle development and other ovarian phenomena.

Ovarian tissue cultures can be used as models of follicle development, ovulation, and follicle atresia and indicate regulatory mechanisms of dynamic ovarian processes.

Mammalian females periodically ovulate an almost constant number of oocytes during each estrus cycle. To sustain such regularity and periodicity, ...

An In Vivo Method to Study Mouse Blood-Testis Barrier Integrity

Spermatogenesis is the development of spermatogonia into mature spermatozoa in the seminiferous tubules of the testis. This process is supported by Sertoli cell junctions at the blood-testis barrier (BTB), which is the tightest tissue barrier in the mammalian body and segregates the seminiferous epithelium into two compartments, a basal and an adluminal. The BTB creates a unique microenvironment for germ cells in meiosis I/II and for the development of postmeiotic spermatids into spermatozoa via spermiogenesis. Here, we describe a reliable assay to monitor BTB integrity of mouse testis in vivo. An intact BTB blocks the diffusion of FITC-conjugated inulin from the basal to the apical compartment of the seminiferous tubules. This technique is suitable for studying gene candidates, viruses, or environmental toxicants that may affect BTB function or integrity, with an easy procedure and a minimal requirement of surgical skills compared to alternative methods.

An In Vivo Method to Study Mouse Blood-Testis Barrier Integrity

Here, we present a protocol to assess the blood-testis barrier integrity by injecting inulin-FITC into testes. This is an efficient in vivo method to study blood-testis barrier integrity that can be compromised by genetic and environmental elements.

Spermatogenesis is the development of spermatogonia into mature spermatozoa in the seminiferous tubules of the testis. This process is supported by ...

Microinjection-based System for In Vivo Implantation of Embryonic Cardiomyocytes in the Avian Embryo

Interpreting the relative impact of cell autonomous patterning versus extrinsic microenvironmental influence on cell lineage determination represents a general challenge in developmental biology research. In the embryonic heart, this can be particularly difficult as regional differences in the expression of transcriptional regulators, paracrine/juxtacrine signaling cues, and hemodynamic force are all known to influence cardiomyocyte maturation. A simplified method to alter a developing cardiomyocyte's molecular and biomechanical microenvironment would, therefore, serve as a powerful technique to examine how local conditions influence cell fate and function. To address this, we have optimized a method to physically transplant juvenile cardiomyocytes into ectopic locations in the heart or the surrounding embryonic tissue. This allows us to examine how microenvironmental conditions influence cardiomyocyte fate transitions at single cell resolution within the intact embryo. Here, we describe a protocol in which embryonic myocytes can be isolated from a variety of cardiac sub-domains, dissociated, fluorescently labeled, and microinjected into host embryos with high precision. Cells can then be directly analyzed in situ using a variety of imaging and histological techniques. This protocol is a powerful alternative to traditional grafting experiments that can be prohibitively difficult in a moving tissue such as the heart. The general outline of this method can also be adapted to a variety of donor tissues and host environments, and its ease of use, low cost, and speed make it a potentially useful application for a variety of developmental studies.

In this method, embryonic cardiac tissues are surgically microdissected, dissociated, fluorescently labeled, and implanted into host embryonic tissues. This provides a platform for studying the individual or tissue level developmental organization under ectopic hemodynamic conditions, and/or altered paracrine/juxtacrine environments.

Interpreting the relative impact of cell autonomous patterning versus extrinsic microenvironmental influence on cell lineage determination represents a ...

Dissection and Live-Imaging of the Late Embryonic Drosophila Gonad

The Drosophila melanogaster male embryonic gonad is an advantageous model to study various aspects of developmental biology including, but not limited to, germ cell development, piRNA biology, and niche formation. Here, we present a dissection technique to live-image the gonad ex vivo during a period when in vivo live-imaging is highly ineffective. This protocol outlines how to transfer embryos to an imaging dish, choose appropriately-staged male embryos, and dissect the gonad from its surrounding tissue while still maintaining its structural integrity. Following dissection, gonads can be imaged using a confocal microscope to visualize dynamic cellular processes. The dissection procedure requires precise timing and dexterity, but we provide insight on how to prevent common mistakes and how to overcome these challenges. To our knowledge this is the first dissection protocol for the Drosophila embryonic gonad, and will permit live-imaging during an otherwise inaccessible window of time. This technique can be combined with pharmacological or cell-type specific transgenic manipulations to study any dynamic processes occurring within or between the&#160;cells in their natural gonadal environment.

Dissection and Live-Imaging of the Late Embryonic Drosophila Gonad

Here, we provide a dissection protocol required to live-image the late embryonic Drosophila male gonad. This protocol will permit observation of dynamic cellular processes under normal conditions or after transgenic or pharmacological manipulation.

The Drosophila melanogaster male embryonic gonad is an advantageous model to study various aspects of developmental biology including, but not limited to, ...

Three and Four-Dimensional Visualization and Analysis Approaches to Study Vertebrate Axial Elongation and Segmentation

Somitogenesis is a hallmark of vertebrate embryonic development. For years, researchers have been studying this process in a variety of organisms using a wide range of techniques encompassing ex vivo and in vitro approaches. However, most studies still rely on the analysis of two-dimensional (2D) imaging data, which limits proper evaluation of a developmental process like axial extension and somitogenesis involving highly dynamic interactions in a complex 3D space. Here we describe techniques that allow mouse live imaging acquisition, dataset processing, visualization and analysis in 3D and 4D to study the cells (e.g., neuromesodermal progenitors) involved in these developmental processes. We also provide a step-by-step protocol for optical projection tomography and whole-mount immunofluorescence microscopy in mouse embryos (from sample preparation to image acquisition) and show a pipeline that we developed to process and visualize 3D image data. We extend the use of some of these techniques and highlight specific features of different available software (e.g., Fiji/ImageJ, Drishti, Amira and Imaris) that can be used to improve our current understanding of axial extension and somite formation (e.g., 3D reconstructions). Altogether, the techniques here described emphasize the importance of 3D data visualization and analysis in developmental biology, and might help other researchers to better address 3D and 4D image data in the context of vertebrate axial extension and segmentation. Finally, the work also employs novel tools to facilitate teaching vertebrate embryonic development.

Here, we describe computational tools and methods that allow visualization and analysis of three and four-dimensional image data of mouse embryos in the context of axial elongation and segmentation, obtained by in toto optical projection tomography, and by live imaging and whole-mount immunofluorescence staining using multiphoton microscopy.

Somitogenesis is a hallmark of vertebrate embryonic development. For years, researchers have been studying this process in a variety of organisms using a ...

Cell Dissociation from the Tongue Epithelium and Mesenchyme/Connective Tissue of Embryonic-Day 12.5 and 8-Week-Old Mice

Cell dissociation has been an essential procedure for studies at the individual-cell level and/or at a cell-population level (e.g.,&#160;single cell RNA sequencing and primary cell culture). Yielding viable, healthy cells in large quantities is critical, and the optimal conditions to do so are tissue dependent. Cell populations in the tongue epithelium and underlying mesenchyme/connective tissue are heterogeneous and tissue structures vary in different regions and at different developmental stages. We have tested protocols for isolating cells from the mouse tongue epithelium and mesenchyme/connective tissue in the early developmental [embryonic day 12.5 (E12.5)] and young adult (8-week) stages. A clean separation between the epithelium and underlying mesenchyme/connective tissue was easy to accomplish. However, to further process and isolate cells, yielding viable healthy cells in large quantities, and careful selection of enzymatic digestion buffer, incubation time, and centrifugation speed and time are critical. Incubation of separated epithelium or underlying mesenchyme/connective tissue in 0.25% Trypsin-EDTA for 30 min at 37 &#176;C, followed by centrifugation at 200 x g for 8 min resulted in a high yield of cells at a high viability rate (&#62;90%) regardless of the mouse stages and tongue regions. Moreover, we found that both dissociated epithelial and mesenchymal/connective tissue cells from embryonic and adult tongues could survive in the cell culture-based medium for at least 3 h without a significant decrease of cell viability. The protocols will be useful for studies that require the preparation of isolated cells from mouse tongues at early developmental (E12.5) and young adult (8-week) stages requiring cell dissociation from different tissue compartments.

We have developed a generalized protocol to dissociate a large quantity of high-quality single cells from the epithelium and mesenchyme/connective tissue of embryonic and adult mouse tongues.

Cell dissociation has been an essential procedure for studies at the individual-cell level and/or at a cell-population level (e.g.,&#160;single cell RNA ...

Analysis of Cell Differentiation, Morphogenesis, and Patterning During Chicken Embryogenesis Using the Soaked-Bead Assay

A multitude of genetic programs is activated during embryonic development that orchestrates cell differentiation to generate an astounding diversity of somatic cells, tissues, and organs. The precise activation of these genetic programs is regulated by morphogens, diffusible molecules that direct cell fate at different thresholds. Understanding how genetic activation coordinates morphogenesis requires the study of local interactions triggered by morphogens during development. The use of beads soaked in proteins or drugs implanted into distinct regions of the embryo enables studying the role of specific molecules in the establishment of digits and other developmental processes. This experimental technique provides information on the control of cell induction, cell fate, and pattern formation. Thus, this soaked bead assay is an extremely powerful and valuable experimental tool applicable to other embryonic models.

The soaked bead assay involves targeted delivery of test reagent at any developmental time point to study the regulation of cell differentiation and morphogenesis. A detailed protocol, applicable to any experimental animal model, for preparing three different types of soaked beads and implanting these in the interdigit of a chicken embryo is presented.

A multitude of genetic programs is activated during embryonic development that orchestrates cell differentiation to generate an astounding diversity of ...