Name: a proximal culture method to study paracrine signaling between cells
Uploaded: 2018-08-28T14:30:00
Description: Watch this Scientific Journal Video about A Proximal Culture Method to Study Paracrine Signaling Between Cells at JoVE.com

We are indebted to the patients for their participation in the tissue collection for these experiments. A DoD OCRP Ovarian Cancer Academy Award (W81XWH-15-0253) and a pilot award from Colleen&#39;s Dream Foundation to Anirban K. Mitra supported this research.

The protocol follows the guidelines of the Institutional Regulatory Board of Indiana University.
1. Cell Preparation
<ol>
	<li>Isolation and culture of human primary mesothelial cells
	<ol>
		<li>Isolate human primary mesothelial cells (HPMCs) from human omentum as described previously17,18 and grow them in complete growth medium [Dulbecco&#8217;s Modified Eagle&#8217;s Medium (DMEM) containing 10% fetal bovine serum...

<ol>
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A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heterotypic+signaling+between+epithelial+tumor+cells+and+fibroblasts+in+carcinoma+formation.">Heterotypic signaling between epithelial tumor cells and fibroblasts in carcinoma formation.</a> Experimental Cell Research. 264 (1), 169-184 (2001).</li><li>Wilson, K. J., 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=EGFR+ligands+exhibit+functional+differences+in+models+of+paracrine+and+autocrine+signaling.">EGFR ligands exhibit functional differences in models of paracrine and autocrine signaling.</a> Growth Factors. 30 (2), 107-116 (2012).</li><li>Kopan, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Notch+signaling.">Notch signaling.</a> Cold Spring Harbor Perspectives in Biology. 4 (10), (2012).</li><li>Singh, A. B., Sugimoto, K., Harris, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Juxtacrine+activation+of+epidermal+growth+factor+(EGF)+receptor+by+membrane-anchored+heparin-binding+EGF-like+growth+factor+protects+epithelial+cells+from+anoikis+while+maintaining+an+epithelial+phenotype.">Juxtacrine activation of epidermal growth factor (EGF) receptor by membrane-anchored heparin-binding EGF-like growth factor protects epithelial cells from anoikis while maintaining an epithelial phenotype.</a> Journal of Biological Chemistry. 282 (45), 32890-32901 (2007).</li><li>Swartz, M. 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=Tumor+microenvironment+complexity:+emerging+roles+in+cancer+therapy.">Tumor microenvironment complexity: emerging roles in cancer therapy.</a> Cancer Research. 72 (10), 2473-2480 (2012).</li><li>Mitra, A. 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=MicroRNAs+reprogram+normal+fibroblasts+into+cancer-associated+fibroblasts+in+ovarian+cancer.">MicroRNAs reprogram normal fibroblasts into cancer-associated fibroblasts in ovarian cancer.</a> Cancer Discovery. 2 (12), 1100-1108 (2012).</li><li>Nieman, K. 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=Adipocytes+promote+ovarian+cancer+metastasis+and+provide+energy+for+rapid+tumor+growth.">Adipocytes promote ovarian cancer metastasis and provide energy for rapid tumor growth.</a> Nature Medicine. 17 (11), 1498-1503 (2011).</li><li>Salimian Rizi, B., 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=Nitric+oxide+mediates+metabolic+coupling+of+omentum-derived+adipose+stroma+to+ovarian+and+endometrial+cancer+cells.">Nitric oxide mediates metabolic coupling of omentum-derived adipose stroma to ovarian and endometrial cancer cells.</a> Cancer Research. 75 (2), 456-471 (2015).</li><li>Mitra, A. 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=Microenvironment-induced+downregulation+of+miR-193b+drives+ovarian+cancer+metastasis.">Microenvironment-induced downregulation of miR-193b drives ovarian cancer metastasis.</a> Oncogene. 34 (48), 5923-5932 (2015).</li><li>Tomar, S., 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=ETS1+induction+by+the+microenvironment+promotes+ovarian+cancer+metastasis+through+focal+adhesion+kinase.">ETS1 induction by the microenvironment promotes ovarian cancer metastasis through focal adhesion kinase.</a> Cancer Letters. 414, 190-204 (2018).</li><li>Ovarian Cancer Metastasis: A Unique Mechanism of Dissemination. Tumor Metastasis Available from: <a target="_blank" href="https://www.intechopen.com/books/tumor-metastasis/ovarian-cancer-metastasis-a-unique-mechanism-of-dissemination">https://www.intechopen.com/books/tumor-metastasis/ovarian-cancer-metastasis-a-unique-mechanism-of-dissemination</a> (2016)</li><li>Iwanicki, M. P., 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=Ovarian+cancer+spheroids+use+myosin-generated+force+to+clear+the+mesothelium.">Ovarian cancer spheroids use myosin-generated force to clear the mesothelium.</a> Cancer Discovery. 1 (2), 144-157 (2011).</li><li>Kenny, H. 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=Mesothelial+cells+promote+early+ovarian+cancer+metastasis+through+fibronectin+secretion.">Mesothelial cells promote early ovarian cancer metastasis through fibronectin secretion.</a> Journal of Clinical Investigation. 124 (10), 4614-4628 (2014).</li><li>Boelens, M. C., 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=Exosome+transfer+from+stromal+to+breast+cancer+cells+regulates+therapy+resistance+pathways.">Exosome transfer from stromal to breast cancer cells regulates therapy resistance pathways.</a> Cell. 159 (3), 499-513 (2014).</li><li>Kalluri, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+biology+and+function+of+exosomes+in+cancer.">The biology and function of exosomes in cancer.</a> Journal of Clinical Investigation. 126 (4), 1208-1215 (2016).</li><li>Kohlhapp, F. J., Mitra, A. K., Lengyel, E., Peter, M. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MicroRNAs+as+mediators+and+communicators+between+cancer+cells+and+the+tumor+microenvironment.">MicroRNAs as mediators and communicators between cancer cells and the tumor microenvironment.</a> Oncogene. 34 (48), 5857-5868 (2015).</li></ol>

Understanding the mechanism of paracrine and juxtacrine signaling between cells is essential for developing a better knowledge of normal tissue homeostasis and disease conditions7,8. Most paracrine signaling studies are conducted by collecting conditioned medium from one cell type and using it to treat the other cell type. This method has an advantage in its inherent simplicity. However, it does not accurately recapitulate the localized concentrations of the secr...

The role of productive reciprocal interactions between cancer cells and the tumor microenvironment in tumor progression has been well established and has become a major focus of research in cancer biology1. Similar instances of bidirectional signaling are crucial during wound healing, immune responses, angiogenesis, stem cell niches, and during development2,3,4,5,6,7,8. A common theme in all these biological processes is that cells respond in various ways to extracellular cues from their microenvironment which determine cell fate, tissue physiology, and disease progression. Therefore, the focus has increasingly turned toward developing a better understanding of the mechanisms involved in such cell-cell communications. A majority of such interactions involve paracrine or juxtacrine signaling between cells. Paracrine signaling involves the secretion of specific signaling factors by one cell which are perceived by corresponding receptors on another cell in the vicinity, triggering a response in it9,10, whereas juxtacrine signaling requires direct contact between cellular components of the two cells involved11,12.
Such signaling is a crucial component in tissue homeostasis, as well as in the tumor microenvironment. The cancer cells benefit from paracrine and juxtacrine factors from cells in the tumor stroma, including cancer-associated fibroblasts (CAFs), immune cells, and adipocytes13,14,15,16. The paracrine signaling can be mediated by growth factors, cytokines, chemokines, etc., while the juxtacrine signaling involves juxtaposed ligands and receptors as in Notch signaling, or interactions between integrins and their respective extracellular matrix proteins. We have demonstrated the importance of reciprocal interactions between ovarian cancer cells and CAFs in tumor progression and metastasis14. Similarly, the interactions of metastasizing ovarian cancer cells with the mesothelial cells covering the site of metastasis regulate key microRNAs and transcription factors in the cancer cells which promote metastatic colonization17,18.
Most studies on paracrine signaling involve the use of a conditioned medium collected from one cell type to treat the second cell type with. While this approach has been widely used, it does not effectively replicate the localized high-concentration levels of the secreted factor in the microenvironment of the receiving cell. It also fails to reproduce the kinetics of the continuous flow of the secreted factor being produced by one cell and received by the neighboring cell. Paracrine signaling is effective over short distances as the secreted factors are at the required concentrations only in the vicinity of the source cell and tend to diffuse and dilute out as the distance increases. This localized high concentration of the secreted factor is essential to trigger a response in the receptor cell. Moreover, the response in the recipient cells is also dependent on the balance of newly secreted factors and their continuous depletion through degradation, binding, and internalization in the recipient cells and diffusion away from the source cell. Conditioned medium can be concentrated to account for the higher localized concentrations present in the microenvironment, but that cannot accurately replicate the exact concentrations. Moreover, it cannot mimic the natural kinetics of production and depletion of the factor involved. To more accurately replicate paracrine signaling and separate it from juxtacrine signaling mechanisms, we have devised a novel proximal culture method, which involves growing the two cell types on either surface of a porous membrane. The pores are small enough to prevent juxtacrine interactions and yet allow the exchange of secreted factors at localized high concentrations. In that way, this system retains the kinetics of production and depletion of the paracrine factors.

<table>
	<tbody>
		<tr>
			<td>24 mm Transwell permeable support with 0.4 &#181;m Pore Polycarbonate Membrane Insert</td>
			<td>Corning (Costar)</td>
			<td>3412</td>
			<td>&#8226; 10 &#181;m thick translucent polycarbonate membrane 
			&#8226; Treated for optimal cell attachment 
			&#8226; Packaged 6 inserts in a 6 well plate, 4 plates per case 
			&#8226; Membrane must be stained for cell visibility 
			&#8226; Sterilized by gamma radiation</td>
		</tr>
		<tr>
			<td>6 well plate</td>
			<td>Corning (Falcon)</td>
			<td>353046</td>
			<td>Flat Bottom, TC-treated, sterile, with Lid</td>
		</tr>
		<tr>
			<td>15 cm culture dish</td>
			<td>Corning (Falcon)</td>
			<td>353025</td>
			<td>Sterile, TC-treated Cell Culture Dish</td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>Corning (Cellgro)</td>
			<td>10-013-CV</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin Streptomycin</td>
			<td>Corning</td>
			<td>30-002-CI</td>
			<td></td>
		</tr>
		<tr>
			<td>MEM Nonessential amino acids</td>
			<td>Corning (Cellgro)</td>
			<td>25-025-CI</td>
			<td></td>
		</tr>
		<tr>
			<td>MEM Vitamins</td>
			<td>Corning (Cellgro)</td>
			<td>25-020-CI</td>
			<td></td>
		</tr>
		<tr>
			<td>0.25% Trypsin, 2.21 mM EDTA</td>
			<td>Corning</td>
			<td>25-053-CI</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal bovine serum</td>
			<td>Atlanta Biologicals</td>
			<td>S11150</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipets</td>
			<td></td>
			<td></td>
			<td>Any make is fine</td>
		</tr>
		<tr>
			<td>CO2 Incubator</td>
			<td></td>
			<td></td>
			<td>Any make is fine</td>
		</tr>
		<tr>
			<td>Biosafety level II cabinet</td>
			<td></td>
			<td></td>
			<td>Any make is fine</td>
		</tr>
		<tr>
			<td>FN1 TaqMan Gene Expression Assay</td>
			<td>ThermoFisher Scientific</td>
			<td>Hs01549976_m1</td>
			<td></td>
		</tr>
		<tr>
			<td>TGFB1 TaqMan Gene Expression Assay</td>
			<td>ThermoFisher Scientific</td>
			<td>Hs00998133_m1</td>
			<td></td>
		</tr>
		<tr>
			<td>CDH1 TaqMan Gene Expression Assay</td>
			<td>ThermoFisher Scientific</td>
			<td>Hs01023895_m1</td>
			<td></td>
		</tr>
		<tr>
			<td>GAPDH TaqMan Gene Expression Assay</td>
			<td>ThermoFisher Scientific</td>
			<td>Hs99999905_m1</td>
			<td></td>
		</tr>
		<tr>
			<td>miRNeasy mini RNA isolation Kit</td>
			<td>Qiagen</td>
			<td>217004</td>
			<td></td>
		</tr>
		<tr>
			<td>High-Capacity cDNA Reverse Transcription Kit</td>
			<td>ThermoFisher Scientific</td>
			<td>43-688-13</td>
			<td></td>
		</tr>
		<tr>
			<td>HeyA8 ovarian cancer cells</td>
			<td>Obtained from Ernst Lengyel Lab, University of Chicago</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>TGF&#946; Neutralizing Antibody</td>
			<td>R&#38;D Systems</td>
			<td>MAB1835-100</td>
			<td></td>
		</tr>
	</tbody>
</table>

a proximal culture method to study paracrine signaling between cells

Intercellular interactions play an important role in many biological processes, including tumor progression, immune responses, angiogenesis, and development. Paracrine or juxtacrine signaling mediates such interactions. The use of a conditioned medium and coculture studies are the most common methods to discriminate between these two types of interactions. However, the effect of localized high concentrations of secreted factors in the microenvironment during the paracrine interactions is not accurately recapitulated by conditioned medium and, thus, may lead to imprecise conclusions. To overcome this problem, we have devised a proximal culture method to study paracrine signaling. The two cell types are grown on either surface of a 10 &#181;m-thick polycarbonate membrane with 0.4 &#181;m pores. The pores allow the exchange of secreted factors and, at the same time, inhibit juxtacrine signaling. The cells can be collected and lysed at the endpoint to determine the effects of the paracrine signaling. In addition to allowing for localized concentration gradients of secreted factors, this method is amenable to experiments involving prolonged periods of culture, as well as the use of inhibitors. While we use this method to study the interactions between ovarian cancer cells and the mesothelial cells they encounter at the site of metastasis, it can be adapted to any two adherent cell types for researchers to study paracrine signaling in various fields, including tumor microenvironment, immunology, and development.

Metastasizing ovarian cancer cells encounter mesothelial cells at the site of metastasis within the peritoneal cavity19. Productive paracrine and juxtacrine interactions with the mesothelial cells help in inducing adaptive responses in the ovarian cancer cells, which enable successful metastasis17,18,20,21. To test the effectiveness of th...

Watch this Scientific Journal Video about A Proximal Culture Method to Study Paracrine Signaling Between Cells at JoVE.com

A Proximal Culture Method to Study Paracrine Signaling Between Cells

Paracrine and juxtacrine cellular interactions play an important role in many biological processes, including tumor progression, immune responses, angiogenesis, and development. Here, a proximal culture method is used to study paracrine signaling where the localized concentrations of the secreted factors are maintained while preventing direct cellular contact.

Intercellular interactions play an important role in many biological processes, including tumor progression, immune responses, angiogenesis, and ...

This method can help answer key questions in the intercellular communications field about reciprocal paracrine versus juxtacrine interactions between two types of cells. The main advantage of this method is that it is a very simple and reproducible technique that accurately captures paracrine signaling under typical culture conditions while at the same time preventing effective juxtacrine signaling. The implications of this technique extend to a better understanding of the mechanism of the crosstalk between the cancer cells and the tumor microenvironment.Though this method can provide insight into the interactions between the cancer cells and the tumor stroma, it can also be applied to other systems such as wound healing and angiogenesis. Begin by detaching the ovarian cancer cells from an 80%confluent mixture with one milliliter of 0.25%trypsin for 40 to 60 seconds, followed by neutralization of the reaction with six milliliters of complete growth medium. Collect the cells by centrifugation and resuspend the pellet in five milliliters of fresh complete growth medium.After counting, dilute the cells to a 100, 000 ovarian cancer cells per milliliter of complete growth medium concentration and place three inverted 0.4 micrometer pore tissue culture treated polycarbonate membrane cell culture inserts per experimental condition in an appropriately sized sterile tissue culture dish. Label the inserts according to the experimental condition and carefully pipette the cancer cells onto the bottom of each insert in concentric circles, starting from the middle of the membrane and moving outward to form an 800 microliter dome. Be extremely careful when seeding the cells onto the bottom surface of the insert so that the dome of the medium containing cells does not run off the edges of the insert during the incubation.When all of the inserts have been seeded, cover the dish and carefully place the inserts into the cell culture incubator. After about four hours, detach the HPMC with two milliliters of 0.25%trypsin for one to two minutes, followed by neutralization of the reaction with 12 milliliters of complete growth medium. Collect the HPMC by centrifugation and resuspend the pellet in 10 milliliters of complete growth medium for counting.Dilute the cells to a 300, 000 HPMC per milliliter of complete growth medium and add 2.5 milliliters of fresh complete growth medium to each well of a six-well culture plate. Using sterile forceps, place each insert right side up into each well of the six-well plate so that the lower ovarian cancer cell attached surfaces are immersed in the media. Then seed 1.5 milliliters of HPMC into the well of each insert.Then place the plate in the cell culture incubator for 72 hours. At the end of the incubation, carefully remove the inserts from each well and rinse both sides of the inserts with PBS. Place each insert into a new six-well plate and add 0.5 milliliters of trypsin to the insert wells and two milliliters of trypsin to the bottom wells.After two minutes at 37 degrees Celsius, add one milliliter of complete growth medium to each insert and carefully pipette the solution a few times without tearing the membrane or spilling the cell suspension into the well below. While pipetting, care should be taken to prevent the cross-contamination of the cells from one chamber with the others. Transfer the resuspended cells into a labeled collection tube and further neutralize the trypsin with an additional two milliliters of complete growth medium.To collect the cells on the bottom of the inserts, flush the bottoms of the membranes two to three times with the two milliliters of trypsin from the corresponding well of the six-well plate so that the detached cells are caught in the appropriate well bottoms. When all of the cells have been detached, neutralize the trypsin in each well with six milliliters of fresh growth medium and transfer the cell suspensions to labeled collection tubes. Then collect all of the cells by centrifugation and resuspend the pellets in 0.7 milliliters of phenol and guanidine thiocyanate-based lysis reagent per tube for RNA extraction and isolation according to standard protocols.Proximal culture of HPMC with ovarian cancer cells results in an increased expression of fibronectin and Transforming Growth Factor or TGF beta one compared to control HPMC seeded on inserts in the absence of cancer cells. The expression of both fibronectin and TGF beta one also significantly increases in ovarian cancer cells upon proximal culture with HPMCs compared to control ovarian cell cultured in the absence of HPMC. Conversely, ovarian cancer cells treated with HPMC conditioned medium demonstrate a significantly reduced fibronectin expression with no change in TGF beta one expression.Blocking of TGF beta one with a neutralizing antibody however results in a significant decrease in TGF beta one expression in ovarian cancer cells in proximal culture with HPMCs. Interestingly, a slight increase in TGF beta one expression is observed in control non-proximally cultured ovarian cancer cells likely as a compensatory response. Proximal culture with ovarian cancer cells slightly increases E-cadherin expression in HPMCs while a marked decrease in E-cadherin is observed in ovarian cancer cells grown in proximity with HPMCs compared to controls further demonstrating the effectiveness of the proximal culture system for studying paracrine signaling between ovarian cancer cells and normal cells at the site of metastasis.While attempting this procedure, it's important to optimize the number of cells seeded and the duration of the proximal culture. Following this procedure, other methods like immunoblotting can be performed to answer additional questions about the changes in protein expression and the activation of downstream processing signaling pathways during the tumor cell mesothelial cell co-culture. After its development, this technique paved the way for researchers in the field of tumor microenvironment, immunology, developmental biology to explore reciprocal paracrine interactions between cells through secreted factors.

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Biology

Testing Visual Sensitivity to the Speed and Direction of Motion in Lizards

Testing visual sensitivity in any species provides basic information regarding behaviour, evolution, and ecology. However, testing specific features of the visual system provide more empirical evidence for functional applications. Investigation into the sensory system provides information about the sensory capacity, learning and memory ability, and establishes known baseline behaviour in which to gauge deviations (Burghardt, 1977). However, unlike mammalian or avian systems, testing for learning and memory in a reptile species is difficult. Furthermore, using an operant paradigm as a psychophysical measure of sensory ability is likewise as difficult. Historically, reptilian species have responded poorly to conditioning trials because of issues related to motivation, physiology, metabolism, and basic biological characteristics. Here, I demonstrate an operant paradigm used a novel model lizard species, the Jacky dragon (Amphibolurus muricatus) and describe how to test peripheral sensitivity to salient speed and motion characteristics. This method uses an innovative approach to assessing learning and sensory capacity in lizards. I employ the use of random-dot kinematograms (RDKs) to measure sensitivity to speed, and manipulate the level of signal strength by changing the proportion of dots moving in a coherent direction. RDKs do not represent a biologically meaningful stimulus, engages the visual system, and is a classic psychophysical tool used to measure sensitivity in humans and other animals. Here, RDKs are displayed to lizards using three video playback systems. Lizards are to select the direction (left or right) in which they perceive dots to be moving. Selection of the appropriate direction is reinforced by biologically important prey stimuli, simulated by computer-animated invertebrates.

Testing visual sensitivity in lizards using an operant conditioning paradigm that employs video playback of random-dot kinematograms and computer-generated invertebrates.

Testing visual sensitivity in any species provides basic information regarding behaviour, evolution, and ecology. However, testing specific features of ...

Tracheotomy: A Method for Transplantation of Stem Cells to the Lung

Lung disease is a leading cause of death and likely to become an epidemic given increases in pollution and smoking worldwide. Advances in stem cell therapy may alleviate many of the symptoms associated with lung disease and induce alveolar repair in adults. Concurrent with the ongoing search for stem cells applicable for human treatment, precise delivery and homing (to the site of disease) must be reassured for successful therapy. Here, I report that stem cells can safely be instilled via the trachea opening a non-stop route to the lung. This method involves a skin incision, caudal insertion of a cannula into and along the tracheal lumen, and injection of a stem cell vehicle mixture into airways of the lung. A broad range of media solutions and stabilizers can be instilled via tracheotomy, resulting in the ability to deliver a wider range of cell types. With alveolar epithelium confining these cells to the lumen, lung expansion and negative pressure during inhalation may also assist in stem cell integration. Tracheal delivery of stem cells, with a quick uptake and the ability to handle a large range of treatments, could accelerate the development of cell-based therapies, opening new avenues for treatment of lung disease.

Significant breakthroughs in stem cell identification are continuously being made. To translate these discoveries, however, novel methods for cellular delivery must be devised. Here I report that the airways provide a safe route for stem cell transplantation to the lungs.

Lung disease is a leading cause of death and likely to become an epidemic given increases in pollution and smoking worldwide. Advances in stem cell ...

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 high-throughput method to globally study the organelle morphology in S. cerevisiae

High-throughput methods to examine protein localization or organelle morphology is an effective tool for studying protein interactions and can help achieve an comprehensive understanding of molecular pathways. In Saccharomyces cerevisiae, with the development of the non-essential gene deletion array, we can globally study the morphology of different organelles like the endoplasmic reticulum (ER) and the mitochondria using GFP (or variant)-markers in different gene backgrounds. However, incorporating GFP markers in each single mutant individually is a labor-intensive process. Here, we describe a procedure that is routinely used in our laboratory. By using a robotic system to handle high-density yeast arrays and drug selection techniques, we can significantly shorten the time required and improve reproducibility. In brief, we cross a GFP-tagged mitochondrial marker (Apc1-GFP) to a high-density array of 4,672 nonessential gene deletion mutants by robotic replica pinning.  Through diploid selection, sporulation, germination and dual marker selection, we recover both alleles. As a result, each haploid single mutant contains Apc1-GFP incorporated at its genomic locus. Now, we can study the morphology of mitochondria in all non-essential mutant background. Using this high-throughput approach, we can conveniently study and delineate the pathways and genes involved in the inheritance and the formation of organelles in a genome-wide setting.

GFP-fusion proteins are widely used to visualize organelles by confocal microscopy. However, screening for mutations that affect the morphology of organelles generally requires individual mutagenesis and is time consuming. Here, we demonstrate a method to simultaneously incorporate organelle-GFP markers in almost 5,000 non-essential genes in yeast.

High-throughput methods to examine protein localization or organelle morphology is an effective tool for studying protein interactions and can help ...

Hi-C: A Method to Study the Three-dimensional Architecture of Genomes.

The three-dimensional folding of chromosomes compartmentalizes the genome and and can bring distant functional elements, such as promoters and enhancers, into close spatial proximity 2-6. Deciphering the relationship between chromosome organization and genome activity will aid in understanding genomic processes, like transcription and replication. However, little is known about how chromosomes fold. Microscopy is unable to distinguish large numbers of loci simultaneously or at high resolution. To date, the detection of chromosomal interactions using chromosome conformation capture (3C) and its subsequent adaptations required the choice of a set of target loci, making genome-wide studies impossible 7-10.
We developed Hi-C, an extension of 3C that is capable of identifying long range interactions in an unbiased, genome-wide fashion. In Hi-C, cells are fixed with formaldehyde, causing interacting loci to be bound to one another by means of covalent DNA-protein cross-links. When the DNA is subsequently fragmented with a restriction enzyme, these loci remain linked. A biotinylated residue is incorporated as the 5' overhangs are filled in. Next, blunt-end ligation is performed under dilute conditions that favor ligation events between cross-linked DNA fragments. This results in a genome-wide library of ligation products, corresponding to pairs of fragments that were originally in close proximity to each other in the nucleus. Each ligation product is marked with biotin at the site of the junction. The library is sheared, and the junctions are pulled-down with streptavidin beads. The purified junctions can subsequently be analyzed using a high-throughput sequencer, resulting in a catalog of interacting fragments.
Direct analysis of the resulting contact matrix reveals numerous features of genomic organization, such as the presence of chromosome territories and the preferential association of small gene-rich chromosomes. Correlation analysis can be applied to the contact matrix, demonstrating that the human genome is segregated into two compartments: a less densely packed compartment containing open, accessible, and active chromatin and a more dense compartment containing closed, inaccessible, and inactive chromatin regions. Finally, ensemble analysis of the contact matrix, coupled with theoretical derivations and computational simulations, revealed that at the megabase scale Hi-C reveals features consistent with a fractal globule conformation.

The Hi-C method allows unbiased, genome-wide identification of chromatin interactions (1). Hi-C couples proximity ligation and massively parallel sequencing. The resulting data can be used to study genomic architecture at multiple scales: initial results identified features such as chromosome territories, segregation of open and closed chromatin, and chromatin structure at the megabase scale.

The three-dimensional folding of chromosomes compartmentalizes the genome and and can bring distant functional elements, such as promoters and enhancers, ...

A PCR-based Genotyping Method to Distinguish Between Wild-type and Ornamental Varieties of Imperata cylindrica

Wild-type I. cylindrica (cogongrass) is one of the top ten worst invasive plants in the world, negatively impacting agricultural and natural resources in 73 different countries throughout Africa, Asia, Europe, New Zealand, Oceania and the Americas1-2. Cogongrass forms rapidly-spreading, monodominant stands that displace a large variety of native plant species and in turn threaten the native animals that depend on the displaced native plant species for forage and shelter. To add to the problem, an ornamental variety [I. cylindrica var. koenigii (Retzius)] is widely marketed under the names of Imperata cylindrica 'Rubra', Red Baron, and Japanese blood grass (JBG). This variety is putatively sterile and noninvasive and is considered a desirable ornamental for its red-colored leaves. However, under the correct conditions, JBG can produce viable seed (Carol Holko, 2009 personal communication) and can revert to a green invasive form that is often indistinguishable from cogongrass as it takes on the distinguishing characteristics of the wild-type invasive variety4 (Figure 1). This makes identification using morphology a difficult task even for well-trained plant taxonomists. Reversion of JBG to an aggressive green phenotype is also not a rare occurrence. Using sequence comparisons of coding and variable regions in both nuclear and chloroplast DNA, we have confirmed that JBG has reverted to the green invasive within the states of Maryland, South Carolina, and Missouri. JBG has been sold and planted in just about every state in the continental U.S. where there is not an active cogongrass infestation. The extent of the revert problem in not well understood because reverted plants are undocumented and often destroyed.
Application of this molecular protocol provides a method to identify JBG reverts and can help keep these varieties from co-occurring and possibly hybridizing. Cogongrass is an obligate outcrosser and, when crossed with a different genotype, can produce viable wind-dispersed seeds that spread cogongrass over wide distances5-7. JBG has a slightly different genotype than cogongrass and may be able to form viable hybrids with cogongrass. To add to the problem, JBG is more cold and shade tolerant than cogongrass8-10, and gene flow between these two varieties is likely to generate hybrids that are more aggressive, shade tolerant, and cold hardy than wild-type cogongrass. While wild-type cogongrass currently infests over 490 million hectares worldwide, in the Southeast U.S. it infests over 500,000 hectares and is capable of occupying most of the U.S. as it rapidly spreads northward due to its broad niche and geographic potential3,7,11. The potential of a genetic crossing is a serious concern for the USDA-APHIS Federal Noxious Week Program. Currently, the USDA-APHIS prohibits JBG in states where there are major cogongrass infestations (e.g., Florida, Alabama, Mississippi). However, preventing the two varieties from combining can prove more difficult as cogongrass and JBG expand their distributions. Furthermore, the distribution of the JBG revert is currently unknown and without the ability to identify these varieties through morphology, some cogongrass infestations may be the result of JBG reverts. Unfortunately, current molecular methods of identification typically rely on AFLP (Amplified Fragment Length Polymorphisms) and DNA sequencing, both of which are time consuming and costly. Here, we present the first cost-effective and reliable PCR-based molecular genotyping method to accurately distinguish between cogongrass and JBG revert.

A PCR-based Genotyping Method to Distinguish Between Wild-type and Ornamental Varieties of Imperata cylindrica

We provide a cost-effective and rapid molecular genotyping protocol that employs variety-specific PCR primers that target DNA sequence differences within the chloroplast trnL-F spacer region to differentiate between varieties of Imperata cylindrica (cogongrass) that cannot be distinguished by morphology alone. These varieties include the federally listed noxious weed, cogongrass and closely-related, wide-spread ornamental variety, I. cylindrica var. koenigii (Japanese blood grass).

Wild-type I. cylindrica (cogongrass) is one of the top ten worst invasive plants in the world, negatively impacting agricultural and natural resources in ...

Visualization of Vascular Ca2+ Signaling Triggered by Paracrine Derived ROS

Oxidative stress has been implicated in a number of pathologic conditions including ischemia/reperfusion damage and sepsis. The concept of oxidative stress refers to the aberrant formation of ROS (reactive oxygen species), which include O2&bull;-, H2O2, and hydroxyl radicals. Reactive oxygen species influences a multitude of cellular processes including signal transduction, cell proliferation and cell death1-6. ROS have the potential to damage vascular and organ cells directly, and can initiate secondary chemical reactions and genetic alterations that ultimately result in an amplification of the initial ROS-mediated tissue damage. A key component of the amplification cascade that exacerbates irreversible tissue damage is the recruitment and activation of circulating inflammatory cells. During inflammation, inflammatory cells produce cytokines such as tumor necrosis factor-&alpha; (TNF&alpha;) and IL-1 that activate endothelial cells (EC) and epithelial cells and further augment the inflammatory response7. Vascular endothelial dysfunction is an established feature of acute inflammation. Macrophages contribute to endothelial dysfunction during inflammation by mechanisms that remain unclear. Activation of macrophages results in the extracellular release of O2&bull;- and various pro-inflammatory cytokines, which triggers pathologic signaling in adjacent cells8. NADPH oxidases are the major and primary source of ROS in most of the cell types. Recently, it is shown by us and others9,10 that ROS produced by NADPH oxidases induce the mitochondrial ROS production during many pathophysiological conditions. Hence measuring the mitochondrial ROS production is equally important in addition to measuring cytosolic ROS. Macrophages produce ROS by the flavoprotein enzyme NADPH oxidase which plays a primary role in inflammation. Once activated, phagocytic NADPH oxidase produces copious amounts of O2&bull;- that are important in the host defense mechanism11,12. Although paracrine-derived O2&bull;- plays an important role in the pathogenesis of vascular diseases, visualization of paracrine ROS-induced intracellular signaling including Ca2+ mobilization is still hypothesis. We have developed a model in which activated macrophages are used as a source of O2&bull;- to transduce a signal to adjacent endothelial cells. Using this model we demonstrate that macrophage-derived O2&bull;- lead to calcium signaling in adjacent endothelial cells.

Visualization of Vascular Ca2+ Signaling Triggered by Paracrine Derived ROS

An efficient method to gain insights into visualizing the paracrine-derived ROS induction of endothelial Ca2+ signaling is described. This method takes advantage of measuring paracrine derived ROS triggered Ca2+ mobilization in vascular endothelial cells in a co-culture model.

Oxidative stress has been implicated in a number of pathologic conditions including ischemia/reperfusion damage and sepsis. The concept of oxidative ...

A High-content Imaging Workflow to Study Grb2 Signaling Complexes by Expression Cloning

Signal transduction by growth factor receptors is essential for cells to maintain proliferation and differentiation and requires tight control. Signal transduction is initiated by binding of an external ligand to a transmembrane receptor and activation of downstream signaling cascades. A key regulator of mitogenic signaling is Grb2, a modular protein composed of an internal SH2 (Src Homology 2) domain flanked by two SH3 domains that lacks enzymatic activity. Grb2 is constitutively associated with the GTPase Son-Of-Sevenless (SOS) via its N-terminal SH3 domain. The SH2 domain of Grb2 binds to growth factor receptors at phosphorylated tyrosine residues thus coupling receptor activation to the SOS-Ras-MAP kinase signaling cascade. In addition, other roles for Grb2 as a positive or negative regulator of signaling and receptor endocytosis have been described. The modular composition of Grb2 suggests that it can dock to a variety of receptors and transduce signals along a multitude of different pathways1-3.
	Described here is a simple microscopy assay that monitors recruitment of Grb2 to the plasma membrane. It is adapted from an assay that measures changes in sub-cellular localization of green-fluorescent protein (GFP)-tagged Grb2 in response to a stimulus4-6. Plasma membrane receptors that bind Grb2 such as activated Epidermal Growth Factor Receptor (EGFR) recruit GFP-Grb2 to the plasma membrane upon cDNA expression and subsequently relocate to endosomal compartments in the cell. In order to identify in vivo protein complexes of Grb2, this technique can be used to perform a genome-wide high-content screen based on changes in Grb2 sub-cellular localization. The preparation of cDNA expression clones, transfection and image acquisition are described in detail below. Compared to other genomic methods used to identify protein interaction partners, such as yeast-two-hybrid, this technique allows the visualization of protein complexes in mammalian cells at the sub-cellular site of interaction by a simple microscopy-based assay. Hence both qualitative features, such as patterns of localization can be assessed, as well as the quantitative strength of the interaction.

A high-content screening method for the identification of novel signaling competent transmembrane receptors is described. This method is amenable to large-scale automation and allows predictions about in vivo protein binding and the sub-cellular localization of protein complexes in mammalian cells.

Signal  transduction by growth factor receptors is essential for cells to maintain  proliferation and differentiation and requires tight control. Signal  ...

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 ...

Mechanical Stimulation-induced Calcium Wave Propagation in Cell Monolayers: The Example of Bovine Corneal Endothelial Cells

Intercellular communication is essential for the coordination of physiological processes between cells in a variety of organs and tissues, including the brain, liver, retina, cochlea and vasculature. In experimental settings, intercellular Ca2+-waves can be elicited by applying a mechanical stimulus to a single cell. This leads to the release of the intracellular signaling molecules IP3 and Ca2+ that initiate the propagation of the Ca2+-wave concentrically from the mechanically stimulated cell to the neighboring cells. The main molecular pathways that control intercellular Ca2+-wave propagation are provided by gap junction channels through the direct transfer of IP3 and by hemichannels through the release of ATP. Identification and characterization of the properties and regulation of different connexin and pannexin isoforms as gap junction channels and hemichannels are allowed by the quantification of the spread of the intercellular Ca2+-wave, siRNA, and the use of inhibitors of gap junction channels and hemichannels. Here, we describe a method to measure intercellular Ca2+-wave in monolayers of primary corneal endothelial cells loaded with Fluo4-AM in response to a controlled and localized mechanical stimulus provoked by an acute, short-lasting deformation of the cell as a result of touching the cell membrane with a micromanipulator-controlled glass micropipette with a tip diameter of less than 1 &mu;m. We also describe the isolation of primary bovine corneal endothelial cells and its use as model system to assess Cx43-hemichannel activity as the driven force for intercellular Ca2+-waves through the release of ATP. Finally, we discuss the use, advantages, limitations and alternatives of this method in the context of gap junction channel and hemichannel research.

Intercellular Ca2+-waves are driven by gap junction channels and hemichannels. Here, we describe a method to measure intercellular Ca2+-waves in cell monolayers in response to a local single-cell mechanical stimulus and its application to investigate the properties and regulation of gap junction channels and hemichannels.

Intercellular communication is essential for the coordination of physiological processes between cells in a variety of organs and tissues, including the ...