We thank Erika Mileti for excellent technical support and Dr. Antonio Di Sabatino for providing the oxygen chambers.
Funding: This work was supported by grants from the 7th EU framework program (IBDase, ERC: Dendroworld) and Fondazione Cariplo to MR and support by a Marie Curie international training mobility network (Cross-Talk, grant agreement No: 21553-2) to KT.

1. Obtaining and Preparing the Tissue
<ol>
	<li>Tissue (healthy or IBD mucosa) is obtained during surgery. Once the specimen is excised transfer to the lab as soon as possible, keeping it in Ca++/Mg++-free HBSS buffer supplemented with Pen/Strep at 4 &deg;C or on ice.</li>
</ol>
*The size of the specimen depends on the availability of the tissue: the part of the tissue obtained, is strictly what is not needed for diagnosis and can vary greatly between healthy and IBD subjects. Healthy tissue is excised from patients undergoing surgery for colon cancer.
<ol start="2">
	<li>Wash the tissue gently and clean it of all mesenteric material. Separate the mucosa layer from the submucosa using sterile scissors and forceps while keeping the tissue in HBSS buffer in a Petri dish (not necessarily immerged). Touch the mucosal surface with the forceps as little as possible.</li>
	<li>Cut mucosa in stripes at least 1 cm wide and as long as possible. Use two sterile scalpels, much as though you were cutting your food.</li>
	<li>Wash clean mucosa gently in HBSS and extend it on a Petri dish with the apical side facing upwards.</li>
</ol>
2. Mounting the Tissue
<ol>
	<li>Prepare fresh medium (tisDMEM). Use DMEM supplemented with Glutamine (2 mM) and NaPyr (1 mM), and add 15% FBS-Na (Fetal Bovine Serum - North American), 1% ITS-X and 200 ng/ml EGF at the time of use.</li>
	<li>Fill a 10 cm Petri dish with the rest of the FBS-Na (use about 30 ml so that metal grids will be completely submerged) and submerge the metal grids. Keep the plate open and support the plastic cylinders on its tap.</li>
</ol>
*The metal grids are made of iron. The mesh is square-shaped with a side of 0.5 mm.
<ol start="3">
	<li>Take 3 &mu;l of surgical glue with a 10 or 20 &mu;l pipette. Apply it carefully to one of the borders of a plastic cylinder while holding it firm with the forceps.</li>
	<li>Gently place the cylinder on the apical side of the mucosa, as close to one of the borders of the strip as possible.</li>
	<li>To give the glue time to firmly attach the cylinder on the tissue, prepare the centre-well organ culture plate: Dispense 850 &mu;l-1 ml of medium in the centre well and support the metal grid on the edges of the plate's central well.</li>
	<li>Cut away excess tissue from the borders of the cylinder using two sterile scalpels as before.</li>
	<li>Gently lift the cylinder with the attached tissue and place the basolateral side on the metal grid in the centre of the plate.</li>
</ol>
3. Stimulation
<ol>
	<li>Use the stimuli of your choice in your preferred concentration.</li>
	<li>Apply appropriate volume in the centre of the plastic cylinder without disturbing the cylinder or the mucosal surface with the pipette tip. Make sure your chosen volume uniformly covers the surface inside the cylinder. Indicated volumes: 
	Large plastic cylinder: 200 &mu;l 
	Medium plastic cylinder: 100 &mu;l 
	Small plastic cylinder: 50 &mu;l</li>
	<li>Incubate for up to 3 hr in a conventional incubator.</li>
</ol>
*If you wish to incubate for longer time points, make sure you use a much smaller volume of stimuli (10-20 &mu;l) and directly place the tissue in an atmosphere of 100% O2 in the pressure of 1 Atm (see 3.5).
<ol start="4">
	<li>Take the medium with the stimuli off the apical surface of the tissue and DO NOT REPLACE with fresh medium, because the tissue does not get enough O2 if a thick layer of medium on the apical face prevents gas exchange. Cover the plate.</li>
	<li>Place the tissue in an atmosphere of 100% O2 in the pressure of 1 Atm.</li>
</ol>
4. Harvesting
<ol>
	<li>After 24 hr of total culture time (&plusmn; 2.5 hr) carefully remove the cylinder from the tissue with the help of a scalpel gently scraping glue off and store it depending on the desired analysis (fix for immunohistochemistry and/or immunofluorescence assays, or snap freeze in liquid N2 for RNA purification and gene expression profiling or protein purification and Western blot assays).</li>
	<li>Harvest the basolateral medium for cytokine secretion profiling. Centrifuge at 8,000 rpm for 7 min to pellet debris, transfer the supernatant in an Eppendorf tube (alternatively aliquot) and immediately store at -20 &deg;C.</li>
</ol>
*if you want to keep supernatants for longer, store them at -80 &deg;C.

<ol>
	<li>Schuller, S., Lucas, M., Kaper, J. B., Giron, J. A., Phillips, A. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+ex+vivo+response+of+human+intestinal+mucosa+to+enteropathogenic+Escherichia+coli+infection.">The ex vivo response of human intestinal mucosa to enteropathogenic Escherichia coli infection.</a> Cell. Microbiol. 11, 521-530 (2009).</li><li>Tsilingiri, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Probiotic+and+postbiotic+activity+in+health+and+disease:+comparison+on+a+novel+polarised+ex-vivo+organ+culture+model.">Probiotic and postbiotic activity in health and disease: comparison on a novel polarised ex-vivo organ culture model.</a> Gut. , (2012).</li><li>Tsilingiri, K., Rescigno, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Should+probiotics+be+tested+on+ex+vivo+organ+culture+models?.">Should probiotics be tested on ex vivo organ culture models?.</a> Gut Microbes. , (2012).</li><li>Mileti, E., Matteoli, G., Iliev, I. D., Rescigno, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+the+immunomodulatory+properties+of+three+probiotic+strains+of+Lactobacilli+using+complex+culture+systems:+prediction+for+in+vivo+efficacy.">Comparison of the immunomodulatory properties of three probiotic strains of Lactobacilli using complex culture systems: prediction for in vivo efficacy.</a> PLoS One. 4, e7056 (2009).</li><li>Cencic, A., Langerholc, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+cell+models+of+the+gut+and+their+applications+in+food+microbiology--a+review.">Functional cell models of the gut and their applications in food microbiology--a review.</a> Int. J. Food Microbiol. 141, S4-S14 (2010).</li><li>te Velde, A. A., Verstege, M. A., Hommes, D. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Critical+appraisal+of+the+current+practice+in+murine+TNBS-induced+colitis.">Critical appraisal of the current practice in murine TNBS-induced colitis.</a> Inflamm. Bowel Dis. 12, 995-999 (2006).</li><li>Senior, P. V., Pritchett, C. J., Sunter, J. P., Appleton, D. R., Watson, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Crypt+regeneration+in+adult+human+colonic+mucosa+during+prolonged+organ+culture.">Crypt regeneration in adult human colonic mucosa during prolonged organ culture.</a> J. Anat. 134, 459-469 (1982).</li><li>Browning, T. H., Trier, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Organ+culture+of+mucosal+biopsies+of+human+small+intestine.">Organ culture of mucosal biopsies of human small intestine.</a> J. Clin. Invest. 48, 1423-1432 (1969).</li><li>Besselink, M. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Probiotic+prophylaxis+in+predicted+severe+acute+pancreatitis:+a+randomised,+double-blind,+placebo-controlled+trial.">Probiotic prophylaxis in predicted severe acute pancreatitis: a randomised, double-blind, placebo-controlled trial.</a> Lancet. 371, 651-659 (2008).</li><li>Lakhdari, O., 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=Identification+of+NF-kappaB+modulation+capabilities+within+human+intestinal+commensal+bacteria.">Identification of NF-kappaB modulation capabilities within human intestinal commensal bacteria.</a> J. Biomed. Biotechnol. 2011, 282356 (2011).</li></ol>

No conflicts of interest declared.

The need for physiologically relevant models on which treatments for human intestinal mucosa can be validly tested has long been emphasized. Many researchers have identified potential artifacts and defects in both cell 5 and mouse models 6 used so far for that purpose. Indeed, even though promising preclinical data is often obtained, these rarely translate to significant clinical benefit.
The method described in this work, presents a relatively simple, yet effective and n...

<table border="1">
	<tbody>
		<tr>
			<td>Regeant</td>
			<td>Company</td>
			<td>Catalog No.</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>Reagents</td>
		</tr>
		<tr>
			<td>10X HBSS</td>
			<td>Eurocalne</td>
			<td>ECM4006XL</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Peni/Strepto</td>
			<td>Lonza</td>
			<td>DE17602E</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Gentamycin</td>
			<td>Gibco</td>
			<td>15750-037</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>Lonza</td>
			<td>BE12614</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>FBS-Na</td>
			<td>Gibco</td>
			<td>16000-044</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>100X ITS-X</td>
			<td>Gibco</td>
			<td>51500-056</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>EGF</td>
			<td>Tebu-bio</td>
			<td>100-15</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>L-Glutamine</td>
			<td>Lonza</td>
			<td>BE17605E</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Non essential aminoacids 100X</td>
			<td>Gibco</td>
			<td>11140-035</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>NaPyr</td>
			<td>Gibco</td>
			<td>11360-039</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>Materials</td>
		</tr>
		<tr>
			<td>Cloning cylinders 6x8 mm</td>
			<td>BellCo</td>
			<td>2090-00608</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Cloning cylinders 8x8 mm</td>
			<td>BellCo</td>
			<td>2090-0080</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Cloning cylinders 10x10 mm</td>
			<td>BellCo</td>
			<td>2090-01010</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Metal grids</td>
			<td>Home made</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Centre well organ culture plate</td>
			<td>BD Falcon</td>
			<td>353037</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Surgical glue (Vetbond)</td>
			<td>3M</td>
			<td>1469SB</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Oxygen Jars</td>
			<td>Home made</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Oxygen tanks</td>
			<td>Air Liquid Sanit&agrave;</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
		</tr>
	</tbody>
</table>

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 succeeded in maintaining healthy and IBD human intestinal mucosa in culture for at least 24 hr preserving the wellbeing of the tissue. In accordance with previous observations 1, this was only possible if the majority of the culture time (at least 85% of total) took place in O2, as the tissue did not survive for 24 hr in conventional incubators (Figure 2). We have also shown that different responses of the explants can be observed on this model depending on the polarity of the st...

Watch this Scientific Journal Video about A Novel Method for the Culture and Polarized Stimulation of Human Intestinal Mucosa Explants at JoVE.com

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

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 ...

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13.0K Views.  European Institute of Oncology. 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.

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

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 ...

Preparation and Culture of Rat Lens Epithelial Explants for Studying Terminal Differentiation

The anterior surface of the ocular lens is covered by a monolayer of epithelial cells, which proliferate in an annular zone underlying the ciliary body.  Following division, these cells migrate posteriorly, where FGF diffusing from the retina induces them to differentiate into a posterior array of elongated lens fiber cells, which compose the bulk of the lens.  Differentiation of lens epithelial cells into lens fibers can be induced in vitro by culturing explants of the central region of the anterior epithelium in the presence of FGF-2.  Explants are prepared from lenses of neonatal rats by removing the lens from the eye and grasping the lens capsule on the posterior side with dissecting tweezers.  The posterior capsule is then gently torn open and pressed down into the plastic bottom of a tissue culture dish. The peripheral regions of the explant are removed with a scalpel and the central area is then cultured in the presence of 100ng/ml FGF-2 for as long as 2-3 weeks, depending on the parameters to be studied.  Since epithelial cells in cultured explants differentiate in approximate synchrony over a period of days to weeks, the time course of signaling and gene expression can be determined using molecular, biochemical, and pharmacological techniques.  Immunofluorescence microscopy is a powerful adjunct to these methods as it demonstrates the subcellular localization of proteins of interest and can reveal the physiological consequences of experimental manipulations of signaling pathways.

Explants of the central region of rat lens epithelia differentiate synchronously when cultured in the presence of FGF-2. Immunofluorescence microscopy of such cultures can provides novel information about gene expression and signaling events associated with terminal differentiation.

The anterior surface of the ocular lens is covered by a monolayer of epithelial cells, which proliferate in an annular zone underlying the ciliary body.  ...

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 ...

Mapping the After-effects of Theta Burst Stimulation on the Human Auditory Cortex with Functional Imaging

Auditory cortex pertains to the processing of sound, which is at the basis of speech or music-related processing1. However, despite considerable recent progress, the functional properties and lateralization of the human auditory cortex are far from being fully understood. Transcranial Magnetic Stimulation (TMS) is a non-invasive technique that can transiently or lastingly modulate cortical excitability via the application of localized magnetic field pulses, and represents a unique method of exploring plasticity and connectivity. It has only recently begun to be applied to understand auditory cortical function 2. 
An important issue in using TMS is that the physiological consequences of the stimulation are difficult to establish. Although many TMS studies make the implicit assumption that the area targeted by the coil is the area affected, this need not be the case, particularly for complex cognitive functions which depend on interactions across many brain regions 3. One solution to this problem is to combine TMS with functional Magnetic resonance imaging (fMRI). The idea here is that fMRI will provide an index of changes in brain activity associated with TMS. Thus, fMRI would give an independent means of assessing which areas are affected by TMS and how they are modulated 4. In addition, fMRI allows the assessment of functional connectivity, which represents a measure of the temporal coupling between distant regions. It can thus be useful not only to measure the net activity modulation induced by TMS in given locations, but also the degree to which the network properties are affected by TMS, via any observed changes in functional connectivity.
Different approaches exist to combine TMS and functional imaging according to the temporal order of the methods. Functional MRI can be applied before, during, after, or both before and after TMS. Recently, some studies interleaved TMS and fMRI in order to provide online mapping of the functional changes induced by TMS 5-7. However, this online combination has many technical problems, including the static artifacts resulting from the presence of the TMS coil in the scanner room, or the effects of TMS pulses on the process of MR image formation. But more importantly, the loud acoustic noise induced by TMS (increased compared with standard use because of the resonance of the scanner bore) and the increased TMS coil vibrations (caused by the strong mechanical forces due to the static magnetic field of the MR scanner) constitute a crucial problem when studying auditory processing. 
This is one reason why fMRI was carried out before and after TMS in the present study. Similar approaches have been used to target the motor cortex 8,9, premotor cortex 10, primary somatosensory cortex 11,12 and language-related areas 13, but so far no combined TMS-fMRI study has investigated the auditory cortex. The purpose of this article is to provide details concerning the protocol and considerations necessary to successfully combine these two neuroscientific tools to investigate auditory processing. 
Previously we showed that repetitive TMS (rTMS) at high and low frequencies (resp. 10 Hz and 1 Hz) applied over the auditory cortex modulated response time (RT) in a melody discrimination task 2. We also showed that RT modulation was correlated with functional connectivity in the auditory network assessed using fMRI: the higher the functional connectivity between left and right auditory cortices during task performance, the higher the facilitatory effect (i.e. decreased RT) observed with rTMS. However those findings were mainly correlational, as fMRI was performed before rTMS. Here, fMRI was carried out before and immediately after TMS to provide direct measures of the functional organization of the auditory cortex, and more specifically of the plastic reorganization of the auditory neural network occurring after the neural intervention provided by TMS. 
Combined fMRI and TMS applied over the auditory cortex should enable a better understanding of brain mechanisms of auditory processing, providing physiological information about functional effects of TMS. This knowledge could be useful for many cognitive neuroscience applications, as well as for optimizing therapeutic applications of TMS, particularly in auditory-related disorders.

Auditory processing is the basis of speech and music-related processing. Transcranial Magnetic Stimulation (TMS) has been used successfully to study cognitive, sensory and motor systems but has rarely been applied to audition. Here we investigated TMS combined with functional Magnetic Resonance Imaging to understand the functional organization of auditory cortex.

Auditory cortex pertains to the processing of sound, which is at the basis of speech or music-related processing1. However, despite considerable recent ...

Blastomere Explants to Test for Cell Fate Commitment During Embryonic Development

Fate maps, constructed from lineage tracing all of the cells of an embryo, reveal which tissues descend from each cell of the embryo. Although fate maps are very useful for identifying the precursors of an organ and for elucidating the developmental path by which the descendant cells populate that organ in the normal embryo, they do not illustrate the full developmental potential of a precursor cell or identify the mechanisms by which its fate is determined. To test for cell fate commitment, one compares a cell's normal repertoire of descendants in the intact embryo (the fate map) with those expressed after an experimental manipulation. Is the cell's fate fixed (committed) regardless of the surrounding cellular environment, or is it influenced by external factors provided by its neighbors? Using the comprehensive fate maps of the Xenopus embryo, we describe how to identify, isolate and culture single cleavage stage precursors, called blastomeres. This approach allows one to assess whether these early cells are committed to the fate they acquire in their normal environment in the intact embryo, require interactions with their neighboring cells, or can be influenced to express alternate fates if exposed to other types of signals.

The fate of an individual embryonic cell can be influenced by inherited molecules and/or by signals from neighboring cells. Utilizing fate maps of the cleavage stage Xenopus embryo, single blastomeres can be identified for culture in isolation to assess the contributions of inherited molecules versus cell-cell interactions.

Fate maps, constructed from lineage tracing all of the cells of an embryo, reveal  which tissues descend from each cell of the embryo.  Although fate maps ...

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 ...

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.

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 ...

Subcloning Plus Insertion (SPI) - A Novel Recombineering Method for the Rapid Construction of Gene Targeting Vectors

Gene targeting refers to the precise modification of a genetic locus using homologous recombination. The generation of novel cell lines and transgenic mouse models using this method necessitates the construction of a &#8216;targeting&#8217; vector, which contains homologous DNA sequences to the target gene, and has for many years been a limiting step in the process. Vector construction can be performed in vivo in Escherichia coli cells using homologous recombination mediated by phage recombinases using a technique termed recombineering. Recombineering is the preferred technique to subclone the long homology sequences (>4kb) and various targeting elements including selection markers that are required to mediate efficient allelic exchange between a targeting vector and its cognate genomic locus. Typical recombineering protocols follow an iterative scheme of step-wise integration of the targeting elements and require intermediate purification and transformation steps. Here, we present a novel recombineering methodology of vector assembly using a multiplex approach. Plasmid gap repair is performed by the simultaneous capture of genomic sequence from mouse Bacterial Artificial Chromosome libraries and the insertion of dual bacterial and mammalian selection markers. This subcloning plus insertion method is highly efficient and yields a majority of correct recombinants. We present data for the construction of different types of conditional gene knockout, or knock-in, vectors and BAC reporter vectors that have been constructed using this method. SPI vector construction greatly extends the repertoire of the recombineering toolbox and provides a simple, rapid and cost-effective method of constructing these highly complex vectors.

Subcloning Plus Insertion SPI - A Novel Recombineering Method for the Rapid Construction of Gene Targeting Vectors

Gene targeting methodologies can be used to generate transgenic mice with knockout, knock-in and tagged alleles. Here, we describe an improved method of recombineering in E. coli, that we term &#8216;subcloning plus insertion&#8217;, which can be used to generate custom gene targeting vectors rapidly.

Gene targeting refers to the precise modification of a genetic locus using homologous recombination. The generation of novel cell lines and transgenic ...

Method for the Assessment of Effects of a Range of Wavelengths and Intensities of Red/near-infrared Light Therapy on Oxidative Stress In Vitro

Red/near-infrared light therapy (R/NIR-LT), delivered by laser or light emitting diode (LED), improves functional and morphological outcomes in a range of central nervous system injuries in vivo, possibly by reducing oxidative stress. However, effects of R/NIR-LT on oxidative stress have been shown to vary depending on wavelength or intensity of irradiation. Studies comparing treatment parameters are lacking, due to absence of commercially available devices that deliver multiple wavelengths or intensities, suitable for high through-put in vitro optimization studies. This protocol describes a technique for delivery of light at a range of wavelengths and intensities to optimize therapeutic doses required for a given injury model. We hypothesized that a method of delivering light, in which wavelength and intensity parameters could easily be altered, could facilitate determination of an optimal dose of R/NIR-LT for reducing reactive oxygen species (ROS) in vitro.
Non-coherent Xenon light was filtered through narrow-band interference filters to deliver varying wavelengths (center wavelengths of 440, 550, 670 and 810nm) and fluences (8.5 x 10-3 to 3.8 x 10-1 J/cm2) of light to cultured cells. Light output from the apparatus was calibrated to emit therapeutically relevant, equal quantal doses of light at each wavelength. Reactive species were detected in glutamate stressed cells treated with the light, using DCFH-DA and H2O2 sensitive fluorescent dyes.&#160;
We successfully delivered light at a range of physiologically and therapeutically relevant wavelengths and intensities, to cultured cells exposed to glutamate as a model of CNS injury. While the fluences of R/NIR-LT used in the current study did not exert an effect on ROS generated by the cultured cells, the method of light delivery is applicable to other systems including isolated mitochondria or more physiologically relevant organotypic slice culture models, and could be used to assess effects on a range of outcome measures of oxidative metabolism.

Method for the Assessment of Effects of a Range of Wavelengths and Intensities of Red/near-infrared Light Therapy on Oxidative Stress In Vitro

Non-coherent Xenon light was passed through narrow-band interference and neutral density filters to deliver light of varying wavelength and intensity to cultured cells. This protocol was used to assess the effects of red/near-infrared light therapy on production of reactive species in vitro: no effects were observed using the tested parameters.

Red/near-infrared light therapy (R/NIR-LT), delivered by laser or light emitting diode (LED), improves functional and morphological outcomes in a range of ...

A Protocol for Lentiviral Transduction and Downstream Analysis of Intestinal Organoids

Intestinal crypt-villus structures termed organoids, can be kept in sustained culture three dimensionally when supplemented with the appropriate growth factors. Since organoids are highly similar to the original tissue in terms of homeostatic stem cell differentiation, cell polarity and presence of all terminally differentiated cell types known to the adult intestinal epithelium, they serve as an essential resource in experimental research on the epithelium. The possibility to express transgenes or interfering RNA using lentiviral or retroviral vectors in organoids has increased opportunities for functional analysis of the intestinal epithelium and intestinal stem cells, surpassing traditional mouse transgenics in speed and cost. In the current video protocol we show how to utilize transduction of small intestinal organoids with lentiviral vectors illustrated by use of doxycylin inducible transgenes, or IPTG inducible short hairpin RNA for overexpression or gene knockdown. Furthermore, considering organoid culture yields minute cell counts that may even be reduced by experimental treatment, we explain how to process organoids for downstream analysis aimed at quantitative RT-PCR, RNA-microarray and immunohistochemistry. Techniques that enable transgene expression and gene knock down in intestinal organoids contribute to the research potential that these intestinal epithelial structures hold, establishing organoid culture as a new standard in cell culture.

In this video protocol we give a step by step explanation of lentiviral transduction in organoids of primary intestinal epithelium and of processing and downstream analysis of these cultures by quantitative RT-PCR, RNA-microarray and immunohistochemistry.

Intestinal crypt-villus structures termed organoids, can be kept in sustained culture three dimensionally when supplemented with the appropriate growth ...