Name: teratoma generation in the testis capsule
Uploaded: 2011-11-07T13:00:00
Duration: 5 min 24 s
Description: Watch this Scientific Journal Video about Teratoma Generation in the Testis Capsule at JoVE.com

This work was funded by CIRM grants #TR-1250, RT1-01108, and CL1-00502.

Note: All animal procedures must be approved by IACUC or equivalent.
All surgical equipment must be sterilized prior to surgery. Sterile gloves, drapes and gauze must be used.
1. Preparation prior to surgery
<ol>
	<li>Obtain 6 week old Mus Musculus CbySmn.CB17-Prkdc SCID/J male mice or other immunocompromised strain of mouse.</li>
	<li>Sterilize all surgical instruments, gloves, and gauze.</li>
	<li>Dissociate hPSCs to be injected with accutase.</li>
	<li>Count cells and resuspend 1,000,000 cells per 20-30 &mu;L in matrigel diluted 1:1 in DMEM/F-12. Keep cells on ice until finished.</li>
	<li>Note that often it is useful to do a run through of the experiment where Trypan Blue is injected. This will help to identify any potential problems before any cells are wasted.</li>
	<li>In the vivarium, anesthetize your mouse according to accepted procedures at your institution. In our experiments, we used an anesthesia machine with isoflurane. Mice were initially put in an induction chamber with 1L/min oxygen and 3-4% isoflurane. Once anesthetized, a nose cone with 1L/min oxygen and 2-3% isoflurane was used. </li>
	<li>Shave the abdomen with clippers, and clean the anterior wall of the mouse abdomen, starting from the center of the abdomen and working clockwise outward. First use Povidone-Iodine solution then wash with 70% ethanol. Repeat 3 times, changing swabs each time. Transfer the animal to a heating pad to keep the animal warm inside a tissue culture or dissecting hood.</li>
	<li>Make a 1 cm longitudinal incision through the skin and peritoneum with sterile surgical scissors just below the level of the hip joint.</li>
	<li>While holding the peritoneum with forceps, reach down toward the right hip with another sterile forcept and pull out the white fatty tissue along with attached testes.</li>
	<li>Place the testes on sterile gauze.</li>
	<li>Fill a tuberculin or Hamilton (1cc) syringe with the hPSCs to be injected. Note that it is a good idea to include a control hPSC line that you know is pluripotent such as WA09 (also known as H9). This way you have a positive control which you can use to determine whether your injection or surgery was flawed.</li>
	<li>Slowly inject the hPSCs (20-30 &mu;L) into the center of the testis capsule away from any major blood vessels, stopping if the testicular capsule begins to swell.</li>
	<li>Remove the needle slowly to avoid reflux of the cells.</li>
	<li>Using forceps, transfer the testes and fatty tissue back to its original position in the abdomen.</li>
	<li>Close up the peritoneum with 2 or 3 reabsorbable sutures and close the skin with autoclips.</li>
	<li>The mouse should be kept warm until it recovers and given some form of analgesic (see what is accepted in your vivarium) after surgery twice a day for 1-2 days. 
	Note that neither the anesthetic nor the analgesic with interfere with tumor development.</li>
	<li>Monitor the animal for tumor growth for 6-12 weeks. Very rarely, tumors may grow to 5 mm in size prior to 6 weeks after injection, thus it is important to monitor the animals. If this happens, animals should be euthanized and the tumors processed and analyzed as usual. </li>
	<li>Once the tumor is palpable and reaches approximately 5mm in size, anesthetize the mouse and sacrifice it according to accepted animal protocol procedures.</li>
	<li>Remove tumor and document accordingly - photograph, measure size, weigh.</li>
	<li>Cut tumor into small pieces and fix in 4% paraformaldehyde solution. Store in 4% paraformaldehyde until samples are sent to a pathologist for sectioning, staining and analysis.</li>
</ol>
2. Representative Results:
When this protocol is done as described and the injected cell line is pluripotent, a palpable, visually obvious, tumor should form within 12 weeks at the most. For established hPSC lines like WA09, we typically see tumors within 6 weeks. For iPSC lines it is not unusual to see tumors within 8-10 weeks. It is very important to inject mice with a line that is known to be pluripotent, as a positive control, in order to be sure that the procedure was performed correctly. Tumors usually look very heterogeneous and have many attached cysts (Figure 1). Analysis of the tumor samples by a pathologist should show differentiated tissues from all three germ layers (Figure 2).
<img alt="Figure 1" src="/files/ftp_upload/3177/3177fig1.jpg" /> 
Figure 1. Typical hPSC derived teratoma in the testis capsule.
Following the described protocol, one million WA09 cells were injected into the testis capsule of an immune compromised mouse. Six weeks later a teratoma was observed. A) Teratoma pulled from the mouse. B) Close up picture of the teratoma. Note the heterogeneity and cyst structures.
<img alt="Figure 2" src="/files/ftp_upload/3177/3177fig2.jpg" /> 
Figure 2. Hematoxylin and Eosin stained sections from the teratoma show tissues from each germ layer. 
Following fixation, the teratoma was sectioned and stained with Hematoxylin and Eosin. Analysis by a pathologist revealed the presence of cells from each of the 3 germ layers.

<ol>
	<li>Bradley, A., Evans, M., Kaufman, M. H., Robertson, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Formation+of+germ-line+chimaeras+from+embryo-derived+teratocarcinoma+cell+lines.">Formation of germ-line chimaeras from embryo-derived teratocarcinoma cell lines.</a> Nature. 309, 255-255 (1984).</li><li>Evans, M. J., Kaufman, M. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Establishment+in+culture+of+pluripotential+cells+from+mouse+embryos.">Establishment in culture of pluripotential cells from mouse embryos.</a> Nature. 292, 154 (1981).</li><li>Martin, G. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+a+pluripotent+cell+line+from+early+mouse+embryos+cultured+in+medium+conditioned+by+teratocarcinoma+stem+cells.">Isolation of a pluripotent cell line from early mouse embryos cultured in medium conditioned by teratocarcinoma stem cells.</a> Proc. Natl. Acad. Sci. U. S. A. 78, 7634-7634 (1981).</li><li>Downing, G. J., Battey, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Technical+assessment+of+the+first+20+years+of+research+using+mouse+embryonic+stem+cell+lines.">Technical assessment of the first 20 years of research using mouse embryonic stem cell lines.</a> Stem Cells. 22, 1168-1168 (2004).</li><li>Thomson, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Embryonic+stem+cell+lines+derived+from+human+blastocysts.">Embryonic stem cell lines derived from human blastocysts.</a> Science. 282, 1145-1145 (1998).</li><li>Reubinoff, B. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Embryonic+stem+cell+lines+from+human+blastocysts:+somatic+differentiation+in+vitro.">Embryonic stem cell lines from human blastocysts: somatic differentiation in vitro.</a> Nat Biotechnol. 18, (2000).</li><li>Muller, F. J., Goldmann, J., Loser, P., Loring, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+call+to+standardize+teratoma+assays+used+to+define+human+pluripotent+cell+lines.">A call to standardize teratoma assays used to define human pluripotent cell lines.</a> Cell Stem Cell. 6, 412-412 (2010).</li><li>Brivanlou, A. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stem+cells.+Setting+standards+for+human+embryonic+stem+cells.">Stem cells. Setting standards for human embryonic stem cells.</a> Science. 300, 913-913 (2003).</li><li>Lensch, M. W., Schlaeger, T. M., Zon, L. I., Daley, G. Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Teratoma+formation+assays+with+human+embryonic+stem+cells:+a+rationale+for+one+type+of+human-animal+chimera.">Teratoma formation assays with human embryonic stem cells: a rationale for one type of human-animal chimera.</a> Cell Stem Cell. 1, 253-25 (2007).</li><li>Gertow, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Organized+development+from+human+embryonic+stem+cells+after+injection+into+immunodeficient+mice.">Organized development from human embryonic stem cells after injection into immunodeficient mice.</a> Stem. Cells. Dev. 13, 421-421 (2004).</li><li>Gertow, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+human+embryonic+stem+cell-derived+teratomas+for+the+assessment+of+pluripotency.">Isolation of human embryonic stem cell-derived teratomas for the assessment of pluripotency.</a> Curr Protoc Stem Cell Biol. Chapter 1, Unit1B 4-Unit1B 4 (2007).</li></ol>

No conflicts of interest declared.

The method presented here provides a highly reliable, straightforward means of generating teratomas from hPSCs in the testis capsule. There are several critical parameters in this technique. In particular, it is important to inject hPSC cell lines that are known to be pluripotent as a control. Other important parameters include the time interval between injection and tumor observation. For cell lines like WA09, teratomas should be observed in 6-8 weeks. For new iPSC lines we find that often 10 weeks are required. Another concern is the number of cells injected. We inject one million cells but the assay can easily be done with fewer cells. In addition, the injection medium is important. We find that we get the best results when the cells are injected in a 1:1 mixture of matrigel and DMEM/F-12, as opposed to PBS or DMEM/F-12.

<table border="1">
	<tbody>
		<tr>
			<td>Name of the reagent</td>
			<td>Company</td>
			<td>Catalogue number</td>
		</tr>
		<tr>
			<td>Accutase</td>
			<td>Invitrogen</td>
			<td>A1110501</td>
		</tr>
		<tr>
			<td>DMEM/F-12</td>
			<td>Invitrogen</td>
			<td>113300-032</td>
		</tr>
		<tr>
			<td>Matrigel</td>
			<td>BD Biosciences</td>
			<td>354277</td>
		</tr>
	</tbody>
</table>

teratoma generation in the testis capsule

Pluripotent stem cells (PSCs) have the unique characteristic that they can differentiate into cells from all three germ layers. This makes them a potentially valuable tool for the treatment of many different diseases. With the advent of induced pluripotent stem cells (iPSCs) and continuing research with human embryonic stem cells (hESCs) there is a need for assays that can demonstrate that a particular cell line is pluripotent. Germline transmission has been the gold standard for demonstrating the pluripotence of mouse embryonic stem cell (mESC) lines1,2,3. Using this assay, researchers can show that a mESC line can make all cell types in the embryo including germ cells4. With the generation of human ESC lines5,6, the appropriate assay to prove pluripotence of these cells was unclear since human ESCs cannot be tested for germline transmission. As a surrogate, the teratoma assay is currently used to demonstrate the pluripotency of human pluripotent stem cells (hPSCs)7,8,9. Though this assay has recently come under scrutiny and new technologies are being actively explored, the teratoma assay is the current gold standard7. In this assay, the cells in question are injected into an immune compromised mouse. If the cells are pluripotent, a teratoma will eventually develop and sections of the tumor will show tissues from all 3 germ layers10. In the teratoma assay, hPSCs can be injected into different areas of the mouse. The most common injection sites include the testis capsule, the kidney capsule, the liver; or into the leg either subcutaneously or intramuscularly11. Here we describe a robust protocol for the generation of teratomas from hPSCs using the testis capsule as the site for tumor growth.

Watch this Scientific Journal Video about Teratoma Generation in the Testis Capsule at JoVE.com

Teratoma Generation in the Testis Capsule

Human pluripotent stem cells (hPSCs) have the potential to treat a myriad of different diseases. The utility of these cells lies in the fact that they can differentiate into any cell type in the body. Here we describe the teratoma assay, which is used to demonstrate the pluripotence of hPSCs.

Pluripotent stem cells (PSCs) have the unique characteristic that they can differentiate into cells from all three germ layers.  This makes them a ...

teratoma-generation-in-the-testis-capsule

Research

JoVE Journal

Medicine

Making Sense of Listening: The IMAP Test Battery

The ability to hear is only the first step towards making sense of the range of information contained in an auditory signal. Of equal importance are the abilities to extract and use the information encoded in the auditory signal. We refer to these as listening skills (or auditory processing AP). Deficits in these skills are associated with delayed language and literacy development, though the nature of the relevant deficits and their causal connection with these delays is hotly debated.
When a child is referred to a health professional with normal hearing and unexplained difficulties in listening, or associated delays in language or literacy development, they should ideally be assessed with a combination of psychoacoustic (AP) tests, suitable for children and for use in a clinic, together with cognitive tests to measure attention, working memory, IQ, and language skills. Such a detailed examination needs to be relatively short and within the technical capability of any suitably qualified professional. Current tests for the presence of AP deficits tend to be poorly constructed and inadequately validated within the normal population. They have little or no reference to the presenting symptoms of the child, and typically include a linguistic component. Poor performance may thus reflect problems with language rather than with AP. To assist in the assessment of children with listening difficulties, pediatric audiologists need a single, standardized child-appropriate test battery based on the use of language-free stimuli.
We present the IMAP test battery which was developed at the MRC Institute of Hearing Research to supplement tests currently used to investigate cases of suspected AP deficits. IMAP assesses a range of relevant auditory and cognitive skills and takes about one hour to complete. It has been standardized in 1500 normally-hearing children from across the UK, aged 6-11 years. Since its development, it has been successfully used in a number of large scale studies both in the UK and the USA. IMAP provides measures for separating out sensory from cognitive contributions to hearing. It further limits confounds due to procedural effects by presenting tests in a child-friendly game-format. Stimulus-generation, management of test protocols and control of test presentation is mediated by the IHR-STAR software platform. This provides a standardized methodology for a range of applications and ensures replicable procedures across testers. IHR-STAR provides a flexible, user-programmable environment that currently has additional applications for hearing screening, mapping cochlear implant electrodes, and academic research or teaching.

A test battery (IMAP) for performing an in-depth assessment of auditory and cognitive abilities contributing to listening skills is described. It is quick to administer, child-friendly and free from linguistic confounds. Stimulus generation and protocol management are controlled via a software platform (IHR-STAR) to ensure replicable procedures.

The ability to hear is only the first step towards making sense of the range of information contained in an auditory signal. Of equal importance are the ...

A Strategy to Identify de Novo Mutations in Common Disorders such as Autism and Schizophrenia

There are several lines of evidence supporting the role of de novo mutations as a mechanism for common disorders, such as autism and schizophrenia. First, the de novo mutation rate in humans is relatively high, so new mutations are generated at a high frequency in the population. However, de novo mutations have not been reported in most common diseases. Mutations in genes leading to severe diseases where there is a strong negative selection against the phenotype, such as lethality in embryonic stages or reduced reproductive fitness, will not be transmitted to multiple family members, and therefore will not be detected by linkage gene mapping or association studies. The observation of very high concordance in monozygotic twins and very low concordance in dizygotic twins also strongly supports the hypothesis that a significant fraction of cases may result from new mutations. Such is the case for diseases such as autism and schizophrenia. Second, despite reduced reproductive fitness1 and extremely variable environmental factors, the incidence of some diseases is maintained worldwide at a relatively high and constant rate. This is the case for autism and schizophrenia, with an incidence of approximately 1% worldwide. Mutational load can be thought of as a balance between selection for or against a deleterious mutation and its production by de novo mutation. Lower rates of reproduction constitute a negative selection factor that should reduce the number of mutant alleles in the population, ultimately leading to decreased disease prevalence. These selective pressures tend to be of different intensity in different environments. Nonetheless, these severe mental disorders have been maintained at a constant relatively high prevalence in the worldwide population across a wide range of cultures and countries despite a strong negative selection against them2. This is not what one would predict in diseases with reduced reproductive fitness, unless there was a high new mutation rate. Finally, the effects of paternal age: there is a significantly increased risk of the disease with increasing paternal age, which could result from the age related increase in paternal de novo mutations. This is the case for autism and schizophrenia3. The male-to-female ratio of mutation rate is estimated at about 4&#x2013;6:1, presumably due to a higher number of germ-cell divisions with age in males. Therefore, one would predict that de novo mutations would more frequently come from males, particularly older males4. A high rate of new mutations may in part explain why genetic studies have so far failed to identify many genes predisposing to complexes diseases genes, such as autism and schizophrenia, and why diseases have been identified for a mere 3% of genes in the human genome. Identification for de novo mutations as a cause of a disease requires a targeted molecular approach, which includes studying parents and affected subjects. The process for determining if the genetic basis of a disease may result in part from de novo mutations and the molecular approach to establish this link will be illustrated, using autism and schizophrenia as examples.

Molecular genetic strategy for finding de novo mutations causing common disorders such as autism and schizophrenia.

There are several lines of evidence supporting the role of de novo mutations as a mechanism for common disorders, such as autism and schizophrenia. First, ...

Technical Aspects of the Mouse Aortocaval Fistula

Technical aspects of creating an arteriovenous fistula in the mouse are discussed. Under general anesthesia, an abdominal incision is made, and the aorta and inferior vena cava (IVC) are exposed. The proximal infrarenal aorta and the distal aorta are dissected for clamp placement and needle puncture, respectively. Special attention is paid to avoid dissection between the aorta and the IVC. After clamping the aorta, a 25 G needle is used to puncture both walls of the aorta into the IVC. The surrounding connective tissue is used for hemostatic compression. Successful creation of the AVF will show pulsatile arterial blood flow in the IVC. Further confirmation of successful AVF can be achieved by post-operative Doppler ultrasound.

The goal is to produce an arteriovenous fistula that is simple and reproducible. This method does not use sutures or glue adhesive. Therefore the samples can be used with the least amount of foreign materials for analysis.

Technical aspects of creating an arteriovenous fistula in the mouse are discussed. Under general anesthesia, an abdominal incision is made, and the aorta ...

Renal Capsule Xenografting and Subcutaneous Pellet Implantation for the Evaluation of Prostate Carcinogenesis and Benign Prostatic Hyperplasia

New therapies for two common prostate diseases, prostate cancer (PrCa) and benign prostatic hyperplasia (BPH), depend critically on experiments evaluating their hormonal regulation. Sex steroid hormones (notably androgens and estrogens) are important in PrCa and BPH; we probe their respective roles in inducing prostate growth and carcinogenesis in mice with experiments using compressed hormone pellets. Hormone and/or drug pellets are easily manufactured with a pellet press, and surgically implanted into the subcutaneous tissue of the male mouse host. We also describe a protocol for the evaluation of hormonal carcinogenesis by combining subcutaneous hormone pellet implantation with xenografting of prostate cell recombinants under the renal capsule of immunocompromised mice. Moreover, subcutaneous hormone pellet implantation, in combination with renal capsule xenografting of BPH tissue, is useful to better understand hormonal regulation of benign prostate growth, and to test new therapies targeting sex steroid hormone pathways.

We describe the manufacture of compressed hormone pellets, as well as subcutaneous surgical implantation into mice. This strategy can be combined with the growth of cell and tissue xenografts under the renal capsule of athymic nude mice to evaluate hormonal carcinogenesis and regulation of benign prostate growth.

New therapies for two common prostate diseases,  prostate cancer (PrCa) and benign prostatic hyperplasia (BPH), depend  critically on experiments ...

Generation and 3-Dimensional Quantitation of Arterial Lesions in Mice Using Optical Projection Tomography

The generation and analysis of vascular lesions in appropriate animal models is a cornerstone of research into cardiovascular disease, generating important information on the pathogenesis of lesion formation and the action of novel therapies. Use of atherosclerosis-prone mice, surgical methods of lesion induction, and dietary modification has dramatically improved understanding of the mechanisms that contribute to disease development and the potential of new treatments.
Classically, analysis of lesions is performed ex vivo using 2-dimensional histological techniques. This article describes application of optical projection tomography (OPT) to 3-dimensional quantitation of arterial lesions. As this technique is non-destructive, it can be used as an adjunct to standard histological and immunohistochemical analyses.
Neointimal lesions were induced by wire-insertion or ligation of the mouse femoral artery whilst atherosclerotic lesions were generated by administration of an atherogenic diet to apoE-deficient mice.
Lesions were examined using OPT imaging of autofluorescent emission followed by complementary histological and immunohistochemical analysis. OPT clearly distinguished lesions from the underlying vascular wall. Lesion size was calculated in 2-dimensional sections using planimetry, enabling calculation of lesion volume and maximal cross-sectional area. Data generated using OPT were consistent with measurements obtained using histology, confirming the accuracy of the technique and its potential as a complement (rather than alternative) to traditional methods of analysis.
This work demonstrates the potential of OPT for imaging atherosclerotic and neointimal lesions. It provides a rapid, much needed ex vivo technique for the routine 3-dimensional quantification of vascular remodelling.

Ex vivo analysis of arterial lesions from animal models of cardiovascular disease classically relies on histological and immunohistochemical techniques. These provide 2-dimensional measurements in 3-dimensional lesions. This manuscript describes the generation of arterial lesions for quantitative analysis in 3-dimensions using optical projection tomography.

The generation and analysis of vascular lesions in appropriate animal models is a cornerstone of research into cardiovascular disease, generating ...

Collection and Extraction of Saliva DNA for Next Generation Sequencing

The preferred source of DNA in human genetics research is blood, or cell lines derived from blood, as these sources yield large quantities of high quality DNA. However, DNA extraction from saliva can yield high quality DNA with little to no degradation/fragmentation that is suitable for a variety of DNA assays without the expense of a phlebotomist and can even be acquired through the mail. However, at present, no saliva DNA collection/extraction protocols for next generation sequencing have been presented in the literature. This protocol optimizes parameters of saliva collection/storage and DNA extraction to be of sufficient quality and quantity for DNA assays with the highest standards, including microarray genotyping and next generation sequencing.

DNA extraction from saliva can provide a readily available source of high molecular weight DNA, with little to no degradation/fragmentation. This protocol provides optimized parameters for saliva collection/storage and DNA extraction to be of sufficient quality and quantity for downstream DNA assays with high quality requirements.

The preferred source of DNA in human genetics research is blood, or cell lines derived from blood, as these sources yield large quantities of high quality ...

An In Vitro Dormancy Model of Estrogen-sensitive Breast Cancer in the Bone Marrow: A Tool for Molecular Mechanism Studies and Hypothesis Generation

The study of breast cancer dormancy in the bone marrow is an exceptionally difficult undertaking due to the complexity of the interactions of dormant cells with their microenvironment, their rarity and the overwhelming excess of hematopoietic cells. Towards this end, we developed an in vitro 2D clonogenic model of dormancy of estrogen-sensitive breast cancer cells in the bone marrow. The model consists of a few key elements necessary for dormancy. These include 1) the use of estrogen sensitive breast cancer cells, which are the type likely to remain dormant for extended periods, 2) incubation of cells at clonogenic density, where the structural interaction of each cell is primarily with the substratum, 3) fibronectin, a key structural element of the marrow and 4) FGF-2, a growth factor abundantly synthesized by bone marrow stromal cells and heavily deposited in the extracellular matrix. Cells incubated with FGF-2 form dormant clones after 6 days, which consist of 12 or less cells that have a distinct flat appearance, are significantly larger and more spread out than growing cells and have large cytoplasm to nucleus ratios. In contrast, cells incubated without FGF-2 form primarily growing colonies consisting of >30 relatively small cells. Perturbations of the system with antibodies, inhibitors, peptides or nucleic acids on day 3 after incubation can significantly affect various phenotypic and molecular aspects of the dormant cells at 6 days and can be used to assess the roles of membrane-localized or intracellular molecules, factors or signaling pathways on the dormant state or survival of dormant cells. While recognizing the in vitro nature of the assay, it can function as a highly useful tool to glean significant information about the molecular mechanisms necessary for establishment and survival of dormant cells. This data can be used to generate hypotheses to be tested in vivo models.

An In Vitro Dormancy Model of Estrogen-sensitive Breast Cancer in the Bone Marrow: A Tool for Molecular Mechanism Studies and Hypothesis Generation

We developed an in vitro model of dormancy in the bone marrow for estrogen-sensitive breast cancer cells. The goal of this protocol is to demonstrate use of the model for the study of the molecular and cellular biology of dormancy and for generation of hypotheses for subsequent testing in vivo.

The study of breast cancer dormancy in the bone marrow is an exceptionally difficult undertaking due to the complexity of the interactions of dormant ...

Rapid and Efficient Generation of Recombinant Human Pluripotent Stem Cells by Recombinase-mediated Cassette Exchange in the AAVS1 Locus

Even with the revolution of gene-targeting technologies led by CRISPR-Cas9, genetic modification of human pluripotent stem cells&#160;(hPSCs)&#160;is still time consuming. Comparative studies that use recombinant lines with transgenes integrated into safe harbor loci could benefit from approaches that use site-specific targeted recombinases, like Cre or FLPe, which are more rapid and less prone to off-target effects. Such methods have been described, although they do not significantly outperform gene targeting in most aspects. Using Zinc-finger nucleases, we previously created a master cell line in the AAVS1 locus of hPSCs&#160;that contains a GFP-Hygromycin-tk expressing cassette, flanked by heterotypic FRT sequences. Here, we describe the procedures to perform FLPe recombinase-mediated cassette exchange (RMCE) using this line. The master cell line is transfected with a RMCE donor vector, which contains a promoterless Puromycin resistance, and with FLPe recombinase. Application of both a positive (Puromycin) and negative (FIAU) selection program leads to the selection of RMCE without random integrations. RMCE generates fully characterized pluripotent polyclonal transgenic lines in 15 d&#160;with 100% efficiency. Despite the recently described limitations of the AAVS1 locus, the ease of the system paves the way for hPSC transgenesis in isogenic settings, is necessary for comparative studies, and enables semi-high-throughput genetic screens for gain/loss of function analysis that would otherwise be highly time consuming.

Rapid and Efficient Generation of Recombinant Human Pluripotent Stem Cells by Recombinase-mediated Cassette Exchange in the AAVS1 Locus

Here we report a rapid and efficient gene editing method based on RMCE in the AAVS1 locus of human Pluripotent Stem Cells (hPSCs) that improves upon previously described systems. Using this technique, isogenic lines can be rapidly and reliably generated for proper comparative studies, facilitating transgenesis-mediated research with hPSCs.

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Drug Repurposing Hypothesis Generation Using the "RE:fine Drugs" System

The promise of drug repurposing is that existing drugs may be used for new disease indications in order to curb the high costs and time for approval. The goal of computational methods for drug repurposing is to enable solutions for safer, cheaper and faster drug discovery. Towards this end, we developed a novel method that integrates genetic and clinical phenotype data from large-scale GWAS and PheWAS studies with detailed drug information on the concept of transitive Drug-Gene-Disease triads. We created "RE:fine Drugs," a freely available, interactive dashboard that automates gene, disease and drug-based searches to identify drug repurposing candidates. This web-based tool supports a user-friendly interface that includes an array of advanced search and export options. Results can be prioritized in a variety of ways, including but not limited to, biomedical literature support, strength and statistical significance of GWAS and/or PheWAS associations, disease indications and molecular drug targets. Here we provide a protocol that illustrates the functionalities available in the "RE:fine Drugs" system and explores the different advanced options through a case study.

Drug Repurposing Hypothesis Generation Using the &quot;RE:fine Drugs&quot; System

Here we describe a protocol using the web-based drug repurposing hypothesis generation tool: "RE:fine Drugs." This protocol can be modified to a user's preferences at the level of the query type (gene, drug or disease) and/or the range of available advanced options.

The promise of drug repurposing is that existing drugs may be used for new disease indications in order to curb the high costs and time for approval. The ...

The Generation of Closed Femoral Fractures in Mice: A Model to Study Bone Healing

Bone fractures impose a tremendous socio-economic burden on patients, in addition to significantly affecting their quality of life. Therapeutic strategies that promote efficient bone healing are non-existent and in high demand. Effective and reproducible animal models of fractures healing are needed to understand the complex biological processes associated with bone regeneration. Many animal models of fracture healing have been generated over the years; however, murine fracture models have recently emerged as powerful tools to study bone healing. A variety of open and closed models have been developed, but the closed femoral fracture model stands out as a simple method for generating rapid and reproducible results in a physiologically relevant manner. The goal of this surgical protocol is to generate unilateral closed femoral fractures in mice and facilitate a post-fracture stabilization of the femur by inserting an intramedullary steel rod. Although devices such as a nail or a screw offer greater axial and rotational stability, the use of an intramedullary rod provides a sufficient stabilization for consistent healing outcomes without producing new defects in the bone tissue or damaging nearby soft tissue. Radiographic imaging is used to monitor the progression of callus formation, bony union, and subsequent remodeling of the bony callus. Bone healing outcomes are typically associated with the strength of the healed bone and measured with torsional testing. Still, understanding the early cellular and molecular events associated with fracture repair is critical in the study of bone tissue regeneration. The closed femoral fracture model in mice with intramedullary fixation serves as an attractive platform to study bone fracture healing and evaluate therapeutic strategies to accelerate healing.

The murine closed femoral fracture model is a powerful platform to study fracture healing and novel therapeutic strategies to accelerate bone regeneration. The goal of this surgical protocol is to generate unilateral closed femoral fractures in mice using an intramedullary steel rod to stabilize the femur.

Bone fractures impose a tremendous socio-economic burden on patients, in addition to significantly affecting their quality of life. Therapeutic strategies ...