Sarah A. Alfaqeeh is funded by Kind Saud University College of Dentistry, Ministry of Higher Education, Kingdom of Saudi Arabia.

1. Set Up
<ol>
	<li>Sharpen the dissection instruments (using a sharpening stone lubricated with mineral oil) and sterilize prior to use for organ culture using a 70% ethanol spray and dry-heat sterilization. Sharpen the dissection needles using electrolysis in 2 M sodium hydroxide using a 12 V supply.</li>
	<li>Prepare the culture medium used for the dissection and culture of embryonic organs, consisting of Advanced Dulbecco&#39;s Modified Eagle Medium F12 (DMEM F12) supplemented with 1% GlutaMAX&#160;and 1% penicillin-streptomycin.</li>
</ol>
2. Embryo Dissection
<ol>
	<li>Cull a timed mated pregnant female using a schedule one method as approved by the Home Office or other governing body. Dissect away the skin around the lower abdomen, and cut open the abdomen using scissors. Locate the two uterine horns, which connect together at the lower midline.</li>
	<li>Dissect out the uterus and place in a tube filled with medium on ice. When on ice, the tissue can be left for several hours.</li>
	<li>Remove the uterus and place in a Petri dish in medium under the microscope. Where possible embryo dissections should be performed in a laminar-flow hood to minimize contamination.</li>
	<li>Dissect out the embryos from the uterus and free them from their extraembryonic tissues.</li>
	<li>Decapitate the embryos using a tungsten needle and transfer the heads into a fresh dish of medium.</li>
	<li>Isolate the mandibles from the heads by placing a needle into the oral cavity and cut through towards the back of the head (Figures 1A and&#160;1B). Isolated mandibles can be temporarily stored in medium on ice while waiting for chopping.</li>
	<li>For whole mandible slices stages E11.5-E15.5 are ideal for tooth germ culture. After E15.5 the developing bone in the mandible is too hard for chopping. Tooth slices can still be made but the bone (dentary and forming alveolar bone) must first be removed by dissection before chopping9. Remove bone carefully using tungsten needles and forceps.</li>
</ol>
3. Embryo Slicing
<ol>
	<li>Prepare the mandible tissue slices using a standard table tissue chopper (Figure 1C). Use a fresh blade after approximately 200 mandibles, and make sure it lies flush with the mounting disc when it falls.</li>
	<li>Clean the mounting disc and blade with 70% ethanol before use. Care must be taken when using the machine, as the blade is very sharp.</li>
	<li>Set the chopper at a cutting distance of between 200-400 &#956;m according to the age of the specimen, and depending on whether the whole tooth germ is required. Set the blade force on maximum.</li>
	<li>Transfer a mandible to the plastic mounting disc using a pipette or forceps. Arrange the mandible on the disc making sure the orientation is still clear. The developing tongue can be used as a useful landmark for determining orientation. For molars use a frontal/transverse orientation (see plane of chopping in Figure 1B), while for incisors use a sagittal slice through the mandible to reflect the different orientation of these teeth as they grow (see plane of chopping in Figure 2A).</li>
	<li>Remove the excess medium from around the tissue using filter paper in order to slightly dry the mandible on the mounting disc.</li>
	<li>Immediately after drying, place the disc on the circular stainless steel table of the chopper. Turn the machine on and press start. The table traverses automatically from left to right while at the same time the chopping arm carrying the blade is raised and dropped at up to 200 strokes/min.</li>
	<li>Turn off the machine once the tissue has been completely sliced. Make sure the blade arm is in the raised position and remove the disc. Do not place fingers under the blade arm or leave the machine unattended when chopping.</li>
	<li>Take the mounting disc and immediately add medium to the slices on the disc in order to prevent excessive drying. Carefully dislodge the sliced tissue from the bottom of the disc using a tungsten needle and then pipette into a small Petri dish of medium (Figure 2A).</li>
	<li>Separate the slices using a needle and then select the tissue slices containing the tissue of interest under a stereomicroscope (Figures 1D, 1E,&#160;and 2B). Place selected slices in fresh culture dishes with medium.</li>
</ol>
4. Slice Culture
<ol>
	<li>Prepare central-well organ culture dishes ready for culture by adding approximately 2 ml of autoclaved water to the outer well to prevent dehydration, and by positioning a metal grid across the center of the dish (Figures 3A and 3B).</li>
	<li>Prepare metal grids by cutting strips approximately 4 cm x 1.5 cm&#160;from sheets of stainless steel mesh. Use a hole punch to make a hole in the center and bend the sides to create a staggered end. The grid should fit flat across the central well, lying parallel to the bottom of the dish (Figures 3A and 3B). Autoclave the grids to sterilize before use.</li>
	<li>Cut a piece of transparent polyethylene terephthalate (PET) membrane (pore size 0.4 &#956;m) large enough to cover the hole in the grid. Place the cut membrane into the dish with the selected slice.</li>
	<li>Place the slice on top of the membrane and then carefully lift the membrane out of the medium, with slice flattened in the center.</li>
	<li>Place the filter on the grid over the circular hole in the center, and add approximately 1 ml of culture medium to the well, up to the level of the membrane.</li>
	<li>For manipulations add proteins or small molecule inhibitors to the medium (for example8).</li>
	<li>Photograph the slice for a record of morphology at day 0 of culture.</li>
	<li>Place the dishes in a humidified atmosphere of 5% CO2 at 37 &#176;C in an incubator.</li>
	<li>Photograph the cultures at regular intervals for on average 7 days. Change the culture medium every 48-72 hr. For photography view the slices with a light source from underneath (Figures 2C-E).</li>
</ol>
5. Lineage Tracing
If lineage tracing is required, lipophilic dyes such as DiI or DiO can be injected into the tooth germ before step 4, slice culture.
<ol>
	<li>Pull glass capillary needles using a needle puller.</li>
	<li>Break the tip of the needle using forceps and place tip down into the dye solution. Leave for a few minutes while the dye fills the tip by capillary action.</li>
	<li>Place the filled needle into a holder and attach via tubing to an injector or mouth aspirator.</li>
	<li>Position the tip of the needle in the culture medium touching the area of the slice due to be labeled. Apply air pressure to displace a small amount of dye out of the needle and onto the tissue.</li>
	<li>Remove needle and check for labeling under fluorescence.</li>
	<li>Successfully labeled slices can be transferred to filters and cultured as described in step 4.</li>
</ol>

<ol>
	<li>Rothova, M., Peterkova, R., Tucker, A. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fate+map+of+the+dental+mesenchyme:+dynamic+development+of+the+dental+papilla+and+follicle.">Fate map of the dental mesenchyme: dynamic development of the dental papilla and follicle.</a> Developmental biology. 366, 244-254 (2012).</li><li>Ferguson, C. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Activin+is+an+essential+early+mesenchymal+signal+in+tooth+development+that+is+required+for+patterning+of+the+murine+dentition.">Activin is an essential early mesenchymal signal in tooth development that is required for patterning of the murine dentition.</a> Genes &amp; development. 12, 2636-2649 (1998).</li><li>Trowell, O. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+culture+of+mature+organs+in+a+synthetic+medium.">The culture of mature organs in a synthetic medium.</a> Experimental cell research. 16, 118-147 (1959).</li><li>Matalova, E., Antonarakis, G. S., Sharpe, P. T., Tucker, A. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+lineage+of+primary+and+secondary+enamel+knots.">Cell lineage of primary and secondary enamel knots.</a> Developmental dynamics : an official publication of the American Association of Anatomists. 233, 754-759 (2005).</li><li>Mitsiadis, T. A., Tucker, A. S., De Bari, C., Cobourne, M. T., Rice, D. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+regulatory+relationship+between+Tbx1+and+FGF+signaling+during+tooth+morphogenesis+and+ameloblast+lineage+determination.">A regulatory relationship between Tbx1 and FGF signaling during tooth morphogenesis and ameloblast lineage determination.</a> Developmental biology. 320, 39-48 (2008).</li><li>Diep, L., Matalova, E., Mitsiadis, T. A., Tucker, A. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Contribution+of+the+tooth+bud+mesenchyme+to+alveolar+bone.">Contribution of the tooth bud mesenchyme to alveolar bone.</a> Journal of experimental zoology. Part B, Molecular. 312B, 510-517 (2009).</li><li>Rothova, M., Feng, J., Sharpe, P. T., Peterkova, R., Tucker, A. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Contribution+of+mesoderm+to+the+developing+dental+papilla.">Contribution of mesoderm to the developing dental papilla.</a> The International journal of developmental biology. 55, 59-64 (2011).</li><li>Buchtova, 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=Initiation+and+patterning+of+the+snake+dentition+are+dependent+on+Sonic+hedgehog+signaling.">Initiation and patterning of the snake dentition are dependent on Sonic hedgehog signaling.</a> Developmental biology. 319, 132-145 (2008).</li><li>Buchtova, M., Stembirek, J., Glocova, K., Matalova, E., Tucker, A. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Early+regression+of+the+dental+lamina+underlies+the+development+of+diphyodont+dentitions.">Early regression of the dental lamina underlies the development of diphyodont dentitions.</a> Journal of dental research. 91, 491-498 (2012).</li><li>Cho, S. W., 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=The+primary+enamel+knot+determines+the+position+of+the+first+buccal+cusp+in+developing+mice+molars.">The primary enamel knot determines the position of the first buccal cusp in developing mice molars.</a> Differentiation; research in biological diversity. 75, 441-451 (2007).</li><li>Sakano, 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=Cell+dynamics+in+cervical+loop+epithelium+during+transition+from+crown+to+root:+implications+for+Hertwig's+epithelial+root+sheath+formation.">Cell dynamics in cervical loop epithelium during transition from crown to root: implications for Hertwig's epithelial root sheath formation.</a> Journal of periodontal research. , (2012).</li><li>Fisher, A. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Morphological+development+in+vitro+of+the+whole+and+halved+lower+molar+tooth+germ+of+the+mouse.">Morphological development in vitro of the whole and halved lower molar tooth germ of the mouse.</a> Archives of oral biology. 16, 1481-1496 (1971).</li><li>Coin, R., Schmitt, R., Lesot, H., Vonesch, J. L., Ruch, J. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regeneration+of+halved+embryonic+lower+first+mouse+molars:+correlation+with+the+distribution+pattern+of+non+dividing+IDE+cells,+the+putative+organizers+of+morphogenetic+units,+the+cusps.">Regeneration of halved embryonic lower first mouse molars: correlation with the distribution pattern of non dividing IDE cells, the putative organizers of morphogenetic units, the cusps.</a> The International journal of developmental biology. 44, 289-295 (2000).</li><li>Kavanagh, K. D., Evans, A. R., Jernvall, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Predicting+evolutionary+patterns+of+mammalian+teeth+from+development.">Predicting evolutionary patterns of mammalian teeth from development.</a> Nature. 449, 427-432 (2007).</li><li>Munne, P. 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The authors declare that they have no competing financial interests.

This method of tooth culture has the advantage that access to the tooth germ is excellent, allowing accurate lineage tracing and placement of beads within the epithelium or the mesenchyme. Defined regions of the developing tooth germ can therefore be specifically targeted. During culture the changing morphology of the tooth germ can be followed, and the effect of manipulations quickly assessed.
The method, however, is only suitable for young tooth germs before substantial formation of hard tis...

For a number of experiments it is important to be able to culture tissue ex vivo to follow development. Culture of developing tissue provides access at defined periods of development and allows manipulation of genes by the addition of factors to the culture medium, or on loaded beads, and by the use of transfection and electroporation1. For many experiments it is important to be able to visualize the tissue as it grows, for example, to follow the fate of lineage labeled cells as the tissue undergoes morphogenesis. This can be particularly problematic for tissues that develop deep within the embryo, which are not obvious when a block of tissue from the embryo is cultured. Teeth are good examples of this, as they develop within the mandible, maxilla and frontal nasal process. When the whole mandible is cultured the superficial structures of the tooth can be viewed but changes in morphology can only be analyzed after sectioning of fixed tissue2. We have adapted a live slice culture technique allowing us to follow tooth germ development and providing access to the different parts of the tooth during development. The technique cultures the tooth germ slices at the gas-liquid interface, using a modified Trowell method3. These slice cultures have been very useful in directly following morphogenesis of the tooth, and allowing lineage tracing of distinct components, such as the enamel knot and the dental papilla and follicle1,4-7. The technique is not limited to mouse embryos and has successfully been used to culture live slices of pig and snake dental tissue8,9. In addition to the benefit of being able to visualize tooth development, the slice method also has the advantage that the thin slices of tissue have increased access to nutrients from the medium and air from the incubator. This results in improved growth of the tooth germs, which match development in vivo, and show invasion of endothelial cells into the papilla7. In contrast, tooth germs in whole mandible cultures develop slower than those in vivo and the center of the culture is often necrotic in long-term cultures. In slice culture, the tooth develops within a slice of the jaw, and its interaction with the surrounding developing bone and other tissues can be monitored. In our method the tissue is chopped straight after dissection with no need to embed in a support medium10,11&#160;and no need for any system to attach the tissue to the chopping block. The method is therefore noninvasive and rapid, allowing many mandibles to be sectioned in one session.

<table border="1">
	<tbody>
		<tr>
			<td>Name of Reagent/Material</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>VWR</td>
			<td>101077Y</td>
			<td>100% ethanol was diluted in distilled H2O to 70%.</td>
		</tr>
		<tr>
			<td>DMEM F12</td>
			<td>Gibco</td>
			<td>12634-010</td>
			<td>Advanced Dulbecco&#39;s Modified Eagle Medium F12</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>GlutaMAX</td>
			<td>Gibco</td>
			<td>35050-061</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>Invitrogen</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin-streptomycin</td>
			<td>Sigma</td>
			<td>P0781</td>
			<td></td>
		</tr>
		<tr>
			<td>DiI (Molecular probes)</td>
			<td>Vybrant</td>
			<td>V-22885</td>
			<td>Cell-labeling solution</td>
		</tr>
		<tr>
			<td></td>
			<td>Invitrogen</td>
			<td></td>
			<td>Cell tracker CM-DiI, C-7000</td>
		</tr>
		<tr>
			<td>DiO (Molecular probes)</td>
			<td>Vybrant</td>
			<td>V22886</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>Invitrogen</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Geminator 500</td>
			<td>Thomas</td>
			<td>Thomas No. 3885A20</td>
			<td>Dry-heat sterilization</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>McIlwain tissue chopper</td>
			<td>Ted Pella, Inc.</td>
			<td>10180</td>
			<td>Standard table</td>
		</tr>
		<tr>
			<td>Organ culture dish (Center-Well Organ Culture Dish)</td>
			<td>Falcon</td>
			<td>353037</td>
			<td></td>
		</tr>
		<tr>
			<td>Membranes (Cell Culture Inserts, 0.4 &#956;m pore size)</td>
			<td>BD Falcon</td>
			<td>353090</td>
			<td>PET track-etched membrane, 6-well format</td>
		</tr>
		<tr>
			<td>Metal grids (Stainless Steel - AISI 304 - Mesh)</td>
			<td>Goodfellow</td>
			<td>FE228710</td>
			<td>(Fe/Cr18/Ni10)</td>
		</tr>
		<tr>
			<td>AutoFlow Direct Heat CO2 Incubator</td>
			<td>Nuaire</td>
			<td>NU-5500</td>
			<td></td>
		</tr>
		<tr>
			<td>Picospritzer III</td>
			<td>Intracel Ltd</td>
			<td>051-0500-900 0-100 psi</td>
			<td>Single channel picospritzer III</td>
		</tr>
		<tr>
			<td>Glass capillary with filament 1 mm</td>
			<td>WPI</td>
			<td>TW100F-4</td>
			<td></td>
		</tr>
		<tr>
			<td>Tungsten wire 0.1 mm</td>
			<td>Goodfellow</td>
			<td>W005138</td>
			<td></td>
		</tr>
		<tr>
			<td>Tungsten wire 0.38 mm</td>
			<td>Goodfellow</td>
			<td>W005155</td>
			<td></td>
		</tr>
		<tr>
			<td>Aspirator tubes</td>
			<td>Sigma</td>
			<td>A5177</td>
			<td>Used for mouth aspiration lineage tracers</td>
		</tr>
	</tbody>
</table>

the slice culture method for following development of tooth germs in explant culture

Explant culture allows manipulation of developing organs at specific time points&#160;and is therefore an important method for the developmental biologist. For many organs it is difficult to access developing tissue to allow monitoring during ex vivo culture. The slice culture method allows access to tissue so that morphogenetic movements can be followed and specific cell populations can be targeted for manipulation or lineage tracing.
In this paper we describe a method of slice culture that has been very successful for culture of tooth germs in a range of species. The method provides excellent access to the tooth germs, which develop at a similar rate to that observed in vivo, surrounded by the other jaw tissues. This allows tissue interactions between the tooth and surrounding tissue to be monitored. Although this paper concentrates on tooth germs, the same protocol can be applied to follow development of a number of other organs, such as salivary glands, Meckel&#39;s cartilage, nasal glands, tongue, and ear.

In order to follow the movement of the first molar dental follicle, 250 &#956;m frontal slices were taken through a mandible using the method described above. The dental follicle is the layer of mesenchyme that surrounds the outer enamel epithelium (OEE) of the developing tooth, and has previously been shown to take part in the formation of tissue of the periodontium 6. Mandibles were dissected at E14.5, the cap stage of tooth development. In the slice the outline of the dental epithelium was clear, and the co...

Watch this Scientific Journal Video about The Slice Culture Method for Following Development of Tooth Germs In Explant Culture at JoVE.com

The Slice Culture Method for Following Development of Tooth Germs In Explant Culture

Here we detail a method to culture tooth germs in mandible slices using a tissue chopper. This method allows unique access to the tooth during development, providing excellent opportunity for manipulation and lineage tracing, not available using more traditional culture methods.

Explant culture allows manipulation of developing organs at specific time points&#160;and is therefore an important method for the developmental ...

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14.0K Views.  King's College London. Here we detail a method to culture tooth germs in mandible slices using a tissue chopper. This method allows unique access to the tooth during development, providing excellent opportunity for manipulation and lineage tracing, not available using more traditional culture methods.

Video: The Slice Culture Method for Following Development of Tooth Germs In Explant Culture

Organotypic Slice Culture of E18 Rat Brains

Organotypic slice cultures from embryonic rodent brains are widely used to study brain development. While there are often advantages to an in-vivo system, organotypic slice cultures allow one to perform a number of manipulations that are not presently feasible in-vivo. To date, organtotypic embryonic brain slice cultures have been used to follow individual cells using time-lapse microscopy, manipulate the expression of genes in the ganglionic emanances (a region that is hard to target by in-utero electroporation), as well as for pharmacological studies. In this video protocol we demonstrate how to make organotypic slice cultures from rat embryonic day 18 embryos. The protocol involves dissecting the embryos, embedding them on ice in low melt agarose, slicing the embedded brains on the vibratome, and finally plating the slices onto filters in culture dishes. This protocol is also applicable in its present form to making organotypic slice cultures from different embryonic ages for both rats and mice. 

Organotypic slice cultures from embryonic rodent brains are widely used to study brain development. While there are often advantages to an in-vivo system, ...

Preparation of Gene Gun Bullets and Biolistic Transfection of Neurons in Slice Culture

Biolistic transfection is a physical means of transfecting cells by bombarding tissue with high velocity DNA coated particles. We provide a detailed protocol for biolistic transfection of rat hippocampal slices, from the initial preparation of DNA coated bullets to the final shooting of the organotypic slice cultures using a gene gun. Gene gun transfection is an efficient and easy means of transfecting neurons and is especially useful for fluorescently labeling a small subset of cells in tissue slice. In this video, we first outline the steps required to coat gold particles with DNA. We next demonstrate how to line the inside of plastic tubing with the gold/DNA bullets, and how to cut this tubing to obtain the plastic cartridges for loading into the gene gun. Finally, we perform biolistic transfection of rat hippocampal slice cultures, demonstrating handling of the Bio-Rad Helios gene gun, and offering trouble shooting advice to obtain healthy and optimally transfected tissue slices.  

We describe a method for preparing DNA coated gold bullets and demonstrate the use of such bullets to biolistically transfect neurons in cultured hippocampal slices.

Biolistic transfection is a physical means of transfecting cells by bombarding tissue with high velocity DNA coated particles. We provide a detailed ...

Method for Culture of Early Chick Embryos ex vivo (New Culture)

The chick embryo is a valuable tool in the study of early embryonic development. Its transparency, accessibility and ease of manipulation, make it an ideal tool for studying  the formation and patterning of brain, neural tube, somite and heart primordia. Applications of chick embryo culture include electroporation of DNA or RNA constructs in order to analyze gene function, grafts of growth factor coated beads such as FGFs and BMPs , as well as whole mount in situ hybridization and immunohistochemistry. This video demonstrates the different steps in chick embryo culture; First, the embryo is explanted in saline. Then, the embryo is centered on a glass ring. The membranes surrounding the embryo are lifted along the walls of the ring. The ring is then placed in a culture dish containing a pool of albumine. The culture dish is sealed and placed in a humid chamber, where the embryo is cultured for up to 24 hrs. Finally, the embryo is removed from the ring, fixed and processed for further applications. A troubleshooting guide is also presented.

Method for Culture of Early Chick Embryos ex vivo New Culture

This video demonstrates New culture, a method by which chick embryos are cultured outside the egg for up to 24 hr. This method enables one to study early development (primitive streak to 14 som.), a period corresponding to E7-9 in mouse. Applications of this technique include electroporation, in situ hybridization and immunohistochemistry.

The chick embryo is a valuable tool in the study of early embryonic development. Its transparency, accessibility and ease of manipulation, make it an ...

A Neuronal and Astrocyte Co-Culture Assay for High Content Analysis of Neurotoxicity

High Content Analysis (HCA) assays combine cells and detection reagents with automated imaging and powerful image analysis algorithms, allowing measurement of multiple cellular phenotypes within a single assay. In this study, we utilized HCA to develop a novel assay for neurotoxicity. Neurotoxicity assessment represents an important part of drug safety evaluation, as well as being a significant focus of environmental protection efforts. Additionally, neurotoxicity is also a well-accepted in vitro marker of the development of neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. Recently, the application of HCA to neuronal screening has been reported. By labeling neuronal cells with &beta;III-tubulin, HCA assays can provide high-throughput, non-subjective, quantitative measurements of parameters such as neuronal number, neurite count and neurite length, all of which can indicate neurotoxic effects. However, the role of astrocytes remains unexplored in these models. Astrocytes have an integral role in the maintenance of central nervous system (CNS) homeostasis, and are associated with both neuroprotection and neurodegradation when they are activated in response to toxic substances or disease states. GFAP is an intermediate filament protein expressed predominantly in the astrocytes of the CNS. Astrocytic activation (gliosis) leads to the upregulation of GFAP, commonly accompanied by astrocyte proliferation and hypertrophy. This process of reactive gliosis has been proposed as an early marker of damage to the nervous system. The traditional method for GFAP quantitation is by immunoassay. This approach is limited by an inability to provide information on cellular localization, morphology and cell number. We determined that HCA could be used to overcome these limitations and to simultaneously measure multiple features associated with gliosis - changes in GFAP expression, astrocyte hypertrophy, and astrocyte proliferation - within a single assay. In co-culture studies, astrocytes have been shown to protect neurons against several types of toxic insult and to critically influence neuronal survival. Recent studies have suggested that the use of astrocytes in an in vitro neurotoxicity test system may prove more relevant to human CNS structure and function than neuronal cells alone. Accordingly, we have developed an HCA assay for co-culture of neurons and astrocytes, comprised of protocols and validated, target-specific detection reagents for profiling &beta;III-tubulin and glial fibrillary acidic protein (GFAP). This assay enables simultaneous analysis of neurotoxicity, neurite outgrowth, gliosis, neuronal and astrocytic morphology and neuronal and astrocytic development in a wide variety of cellular models, representing a novel, non-subjective, high-throughput assay for neurotoxicity assessment. The assay holds great potential for enhanced detection of neurotoxicity and improved productivity in neuroscience research and drug discovery.

This article describes a novel protocol and reagent set designed for sensitive measurement of neurotoxic effects of compounds and treatments on co-cultures of neurons and astrocytes using high content analysis. Results demonstrate that high content analysis represents an exciting novel technology for neurotoxicity assessment.

High Content Analysis (HCA) assays combine cells and detection reagents with automated imaging and powerful image analysis algorithms, allowing ...

Culture and Maintenance of Human Embryonic Stem Cells  

Human embryonic stem (hES) cells must be monitored and cared for in order to maintain healthy, undifferentiated cultures. At minimum, the cultures must be  fed  every day by performing a complete medium change to replenish lost nutrients and to keep the cultures free of unwanted differentiation factors. Although a small amount of differentiation is normal and expected in stem cell cultures, the culture should be routinely cleaned up by manually removing, or "picking" differentiated areas. Identifying and removing excess differentiation from hES cell cultures are essential techniques in the maintenance of a healthy population of cells.

Culture and Maintenance of Human Embryonic Stem Cells

This protocol demonstrates how to maintain healthy, undifferentiated human embryonic stem (ES) cells.

Human embryonic stem (hES) cells must be monitored and cared for in order to maintain healthy, undifferentiated cultures. At minimum, the cultures must be ...

The Method of Rodent Whole Embryo Culture using the Rotator-type Bottle Culture System

Whole embryo culture (WEC) technique has been developed in 1950's by New and his colleagues, and applied for developmental biology 1. Although development and growth of mammalian embryos are critically dependent on the function of the placenta, WEC technique allows us to culture mouse and rat embryos ex vivo condition during limited periods corresponding to midgestation stages during embryonic day (E) 6.5-E12.5 in the mouse or E8.5-E14.5 in the rat 2, 3, 4. In WEC, we can directly target desired areas of embryos using fine glass capillaries because embryos can be manipulated under the microscope. Therefore, rodent WEC is very useful technique when we want to study dynamic developmental processes of postimplanted mammalian embryos. Up to date, several types of WEC systems have been developed 1. Among those, the rotator-type bottle culture system is most popular and suitable for long-term culture of embryos at midgestation, i.e., after E9.5 and E11.5 in the mouse and rat, respectively 1. In this video protocol, we demonstrate our standard procedures of rat WEC after E12.5 using a refined model of the original rotator system, which was designed by New and Cockroft 5, 6, and introduce various applications of WEC technique for studies in mammalian developmental biology.

Whole embryo culture technique allows us to culture mouse and rat embryos ex vivo condition during limited periods corresponding to midgestation stages. In this video protocol, we demonstrate our standard procedures of rat whole embryo culture after E12.5 using the rotator-type bottle culture system.

Whole embryo culture (WEC) technique has been developed in 1950's by New and his colleagues, and applied for developmental biology 1. Although development ...

A Novel Method for the Culture and Polarized Stimulation of Human Intestinal Mucosa Explants

Few models currently exist to realistically simulate the complex human intestine's micro-environment, where a variety of interactions take place. Proper homeostasis directly depends on these interactions, as they shape an entire immunological response inducing tolerance against food antigens while at the same time mounting effective immune responses against pathogenic microbes accidentally ingested with food.
Intestinal homeostasis is preserved also through various complex interactions between the microbiota (including food-associated beneficial bacterial strains) and the host, that regulate the attachment/degradation of mucus, the production of antimicrobial peptides by the epithelial barrier, and the "education" of epithelial cells' that controls the tolerogenic or immunogenic phenotype of unique, gut-resident lymphoid cells' populations. These interactions have been so far very difficult to reproduce with in vitro assays using either cultured cell lines or peripheral blood mononuclear cells. In addition, mouse models differ substantially in components of the intestinal mucosa (mucus layer organization, commensal bacteria community) with respect to the human gut. Thus, studies of a variety of treatments to be brought in the clinics for important stress-related or pathological conditions such as irritable bowel syndrome, inflammatory bowel disease or colorectal cancer have been difficult to carry out.
To address these issues, we developed a novel system that enables us to stimulate explants of human intestinal mucosa that retain their in situ conditioning by the host microbiota and immune response, in a polarized fashion. Polarized apical stimulation is of great importance for the outcome of the elicited immune response. It has been repeatedly shown that the same stimuli can produce completely different responses when they bypass the apical face of the intestinal epithelium, stimulating epithelial cells basolaterally or coming into direct contact with lamina propria components, switching the phenotype from tolerogenic to immunogenic and causing unnecessary and excessive inflammation in the area.
We achieved polarized stimulation by gluing a cave cylinder which delimited the area of stimulation on the apical face of the mucosa as will be described in the protocol. We used this model to examine, among others, differential effects of three different Lactobacilli strains. We show that this model system is very powerful to assess the immunomodulatory properties of probiotics in healthy and disease conditions.

We introduce a novel method for the maintenance of human intestinal mucosa in culture and monitoring of the response to various types of stimuli over at least 24 hrs. With our method, the polarity of the tissue is maintained, allowing for a physiological stimulation via the apical route.

Few models currently exist to realistically simulate the complex human intestine's micro-environment, where a variety of interactions take place. Proper ...

A Novel Ex vivo Culture Method for the Embryonic Mouse Heart

Developmental studies in the mouse are hampered by the inaccessibility of the embryo during gestation. Thus, protocols to isolate and culture individual organs of interest are essential to provide a method of both visualizing changes in development and allowing novel treatment strategies. To promote the long-term culture of the embryonic heart at late stages of gestation, we developed a protocol in which the excised heart is cultured in a semi-solid, dilute Matrigel. This substrate provides enough support to maintain the three-dimensional structure but is flexible enough to allow continued contraction. In brief, hearts are excised from the embryo and placed in a mixture of cold Matrigel diluted 1:1 with growth medium. After the diluted Matrigel solidifies, growth medium is added to the culture dish. Hearts excised as late as embryonic day 16.5 were viable for four days post-dissection. Analysis of the coronary plexus shows that this method does not disrupt coronary vascular development. Thus, we present a novel method for long-term culture of embryonic hearts.

A Novel Ex vivo Culture Method for the Embryonic Mouse Heart

Developmental studies in the mouse are hampered by the inaccessibility of the embryo during gestation. To promote the long-term culture of the embryonic heart at late stages of gestation, we developed a protocol in which the excised heart is cultured in a semi-solid, dilute Matrigel.

Developmental studies in the mouse are hampered  by the inaccessibility of the embryo during gestation. Thus, protocols to  isolate and culture individual ...

Mouse Embryonic Development in a Serum-free Whole Embryo Culture System

Mid-gestation stage mouse embryos were cultured utilizing a serum-free culture medium prepared from commercially available stem cell media supplements in an oxygenated rolling bottle culture system. Mouse embryos at E10.5 were carefully isolated from the uterus with intact yolk sac and in a process involving precise surgical maneuver the embryos were gently exteriorized from the yolk sac while maintaining the vascular continuity of the embryo with the yolk sac. Compared to embryos prepared with intact yolk sac or with the yolk sac removed, these embryos exhibited superior survival rate and developmental progression when cultured under similar conditions. We show that these mouse embryos, when cultured in a defined medium in an atmosphere of 95% O2 / 5% CO2 in a rolling bottle culture apparatus at 37 &#176;&#8203;C for 16-40 hr, exhibit morphological growth and development comparable to the embryos developing in utero. We believe this method will be useful for investigators needing to utilize whole embryo culture to study signaling interactions important in embryonic organogenesis.

Serum utilized in embryo cultures contains unknown components that can affect the outcome of experiments especially in studies involving signaling interactions. Here we utilized a serum-free oxygenated culture system and show that mid-gestation mouse embryos cultured for 16-40 hr&#160;exhibit morphological development comparable to embryos developing in utero.

Mid-gestation stage mouse embryos were cultured utilizing a serum-free culture medium prepared from commercially available stem cell media supplements in ...

Dissection of Xenopus laevis Neural Crest for in vitro Explant Culture or in vivo Transplantation

The neural crest (NC) is a transient dorsal neural tube cell population that undergoes an epithelium-to-mesenchyme transition (EMT) at the end of neurulation, migrates extensively towards various organs, and differentiates into many types of derivatives (neurons, glia, cartilage and bone, pigmented and endocrine cells). In this protocol, we describe how to dissect the premigratory cranial NC from Xenopus laevis embryos, in order to study NC development in vivo and in vitro. The frog model offers many advantages to study early development; abundant batches are available, embryos develop rapidly, in vivo gain and loss of function strategies allow manipulation of gene expression prior to NC dissection in donor and/or host embryos. The NC explants can be plated on fibronectin and used for in vitro studies. They can be cultured for several days in a serum-free defined medium. We also describe how to graft NC explants back into host embryos for studying NC migration and differentiation in vivo.

Dissection of Xenopus laevis Neural Crest for in vitro Explant Culture or in vivo Transplantation

This protocol describes how to dissect premigratory cranial neural crest (NC) from Xenopus laevis neurulas. These explants can be plated on fibronectin and cultured in vitro, or grafted back into host embryos. This technique allows studying the mechanisms of NC epithelium-to-mesenchyme transition, migration, and differentiation.