Name: a simple mechanical procedure to create limbal stem cell deficiency in mouse
Uploaded: 2016-11-17T13:00:00
Description: Watch this Scientific Journal Video about A Simple Mechanical Procedure to Create Limbal Stem Cell Deficiency in Mouse at JoVE.com

The authors thank Ruth Zelkha, MS, for her generous assistance in imaging. This research was supported by Clinical Scientist Development Program Award K12EY021475 to M.E., grant R01 EY024349-01A1 to A.R.D., core grant EY01792 from the National Eye Institute, NIH, and an unrestricted grant from Research to Prevent Blindness. A.R.D. is the recipient of a Career Development Award from Research to Prevent Blindness.

All procedures performed on animals comply with the Association for Research in Vision and Ophthalmology statements for animal use in vision research. Fourteen four- to six-month-old male/female C57BL/6J wild type mice were used: ten mice for the injury model and four as control animals (unwounded corneas).
1. Animal Preparation
<ol>
	<li>Anesthetize a mouse with an intraperitoneal injection of a 100 mg/kg ketamine and 5 mg/kg xylazine mixture. After the anesthesia has taken effect, pinch th...

<ol>
	<li>Afsharkhamseh, N., 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=Stability+of+limbal+stem+cell+deficiency+after+mechanical+and+thermal+injuries+in+mice.">Stability of limbal stem cell deficiency after mechanical and thermal injuries in mice.</a> Exp. Eye Res. 145, 88-92 (2015).</li><li>Dor&#224;, N. J., Hill, R. E., Collinson, J. M., West, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lineage+tracing+in+the+adult+mouse+corneal+epithelium+supports+the+limbal+epithelial+stem+cell+hypothesis+with+intermittent+periods+of+stem+cell+quiescence.">Lineage tracing in the adult mouse corneal epithelium supports the limbal epithelial stem cell hypothesis with intermittent periods of stem cell quiescence.</a> Stem Cell Res. 15 (3), 665-677 (2015).</li><li>Ahmad, S., Osei-Bempong, C., Dana, R., Jurkunas, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+culture+and+transplantation+of+human+limbal+stem+cells.">The culture and transplantation of human limbal stem cells.</a> J. Cell Physiol. 225 (1), 15-19 (2010).</li><li>Kolli, S., Ahmad, S., Lako, M., Figueiredo, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Successful+clinical+implementation+of+corneal+epithelial+stem+cell+therapy+for+treatment+of+unilateral+limbal+stem+cell+deficiency.">Successful clinical implementation of corneal epithelial stem cell therapy for treatment of unilateral limbal stem cell deficiency.</a> Stem Cells. 28 (3), 597-610 (2010).</li><li>Ahmad, S., Figueiredo, F., Lako, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Corneal+epithelial+stem+cells:+characterization,+culture+and+transplantation.">Corneal epithelial stem cells: characterization, culture and transplantation.</a> Regen. Med. 1 (1), 29-44 (2006).</li><li>He, H., Yiu, S. 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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=Wounding+the+cornea+to+learn+how+it+heals.">Wounding the cornea to learn how it heals.</a> Exp. Eye Res. 121, 178-193 (2014).</li><li>Amirjamshidi, H., 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=Limbal+fibroblast+conditioned+media:+a+non-invasive+treatment+for+limbal+stem+cell+deficiency.">Limbal fibroblast conditioned media: a non-invasive treatment for limbal stem cell deficiency.</a> Mol. Vis. 17, 658-666 (2011).</li><li>Li, F. 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=Evaluation+of+the+AlgerBrush+II+rotating+burr+as+a+tool+for+inducing+ocular+surface+failure+in+the+New+Zealand+White+rabbit.">Evaluation of the AlgerBrush II rotating burr as a tool for inducing ocular surface failure in the New Zealand White rabbit.</a> Exp. Eye Res. 147, 1-11 (2016).</li><li>Ti, S. E., Anderson, D., Touhami, A., Kim, C., Tseng, S. C. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Factors+affecting+outcome+following+transplantation+of+ex+vivo+expanded+limbal+epithelium+on+amniotic+membrane+for+total+limbal+deficiency+in+rabbits.">Factors affecting outcome following transplantation of ex vivo expanded limbal epithelium on amniotic membrane for total limbal deficiency in rabbits.</a> Invest. Ophthalmol. Vis. Sci. 43 (8), 2584-2592 (2002).</li><li>Ma, Y., 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=Reconstruction+of+chemically+burned+rat+corneal+surface+by+bone+marrow-derived+human+mesenchymal+stem+cells.">Reconstruction of chemically burned rat corneal surface by bone marrow-derived human mesenchymal stem cells.</a> Stem Cells. 24 (2), 315-321 (2006).</li><li>Bu, 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=Effects+of+activated+omental+cells+on+rat+limbal+corneal+alkali+injury.">Effects of activated omental cells on rat limbal corneal alkali injury.</a> Exp. Eye Res. 121, 143-146 (2014).</li><li>Luengo Gimeno, F., Lavigne, V., Gatto, S., Croxatto, J. O., Correa, L., Gallo, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Advances+in+corneal+stem-cell+transplantation+in+rabbits+with+severe+ocular+alkali+burns.">Advances in corneal stem-cell transplantation in rabbits with severe ocular alkali burns.</a> J. Cataract Refract. Surg. 33 (11), 1958-1965 (2007).</li><li>Lin, Z., 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=A+mouse+model+of+limbal+stem+cell+deficiency+induced+by+topical+medication+with+the+preservative+benzalkonium+chloride.">A mouse model of limbal stem cell deficiency induced by topical medication with the preservative benzalkonium chloride.</a> Invest. Ophthalmol. Vis. Sci. 54 (9), 6314-6325 (2013).</li><li>Huang, A. J., Tseng, S. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Corneal+epithelial+wound+healing+in+the+absence+of+limbal+epithelium.">Corneal epithelial wound healing in the absence of limbal epithelium.</a> Invest. Ophthalmol. Vis. Sci. 32 (1), 96-105 (1991).</li><li>Liu, C. Y., 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=Cornea-specific+expression+of+K12+keratin+during+mouse+development.">Cornea-specific expression of K12 keratin during mouse development.</a> Curr. Eye Res. 12 (11), 963-974 (1993).</li><li>Nakatsu, M. N., Gonz&#225;lez, S., Mei, H., Deng, S. X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+limbal+mesenchymal+cells+support+the+growth+of+human+corneal+epithelial+stem/progenitor+cells.">Human limbal mesenchymal cells support the growth of human corneal epithelial stem/progenitor cells.</a> Invest. Ophthalmol. Vis. Sci. 55 (10), 6953-6959 (2014).</li><li>Pajoohesh-Ganji, A., Pal-Ghosh, S., Tadvalkar, G., Stepp, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Corneal+goblet+cells+and+their+niche:+implications+for+corneal+stem+cell+deficiency.">Corneal goblet cells and their niche: implications for corneal stem cell deficiency.</a> Stem Cells. 30 (9), 2032-2043 (2012).</li><li>McCloy, R. A., Rogers, S., Caldon, C. 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This article describes a reproducible and relatively simple technique to create a mouse model of LSCD. There are several important aspects of this model that are worth noting. First, unlike models that use chemicals11, 12, the injury primarily involves the surface epithelium (and basement membrane), with minimal damage to the underlying corneal stroma or to other intraocular structures. Thus, there is only limited inflammation and scarring, both of which can complicate the procedure and make it more difficult ...

The corneal epithelium is required to maintain the clarity and integrity of the cornea. It is constantly renewed throughout life by the epithelial stem cells residing in the limbus-a narrow zone at the junction of the cornea and the conjunctiva. These self-renewing limbal stem cells play a crucial role in regenerating the corneal epithelium, both normally and after injury. Partial or complete depletion of these stem cells will result in recurrent corneal erosions, pain, corneal scarring and neovascularization, appearance of goblet cells, and if left untreated, corneal blindness. This condition is known as limbal stem cell deficiency (LSCD) and can be idiopathic; hereditary; or acquired due to chemical or thermal injuries, long-term contact lens wear, and chronic inflammation1-6.
Research on LSCD requires a suitable animal model that not only mimics the disease in humans, but is reproducible and sustainable, with the least amount of injury to other corneal and ocular structures. This model is necessary to assess treatments and to clarify the disease mechanisms at molecular and cellular levels. As described before1, with the use of a rotating burr, one can easily develop a mouse model of LSCD that features the aforementioned advantages and persists for at least three months. The goal of this study is to present a simple, reproducible, and sustainable mouse model of LSCD.
The rotating burr is a handy tool that evenly removes the epithelium without injuring the underlying stroma1. It has been used to induce central corneal erosion7, 8 in wound healing studies. The hereby-presented technique to create LSCD in a mouse has not been reported before. Previously introduced methods of scraping the epithelium with a blunt spatula result in a less uniform injury-particularly at the limbus-and a more variable phenotype1, 9, with more restoration of normal corneal epithelium1. Unlike the blunt scraper, the rotating burr removes the epithelial basement membrane as well7, 8, 10. Other reported methods to sever stem cells involve the use of chemicals, such as sodium hydroxide, n-heptanol, and benzalkonium chloride, which not only may induce unwanted injury to underlying eye structures, but also may lead to significant inflammation and subsequent corneal opacification or epithelial squamous metaplasia11-15. The rotating burr is not associated with these severe complications. Surgically removing the limbal epithelium, alone or with the use of chemicals10, 11, 16, is more difficult to perform and is not the best option in animals with small eyes and a thin limbal epithelia (like mice). In addition, surprisingly, limbectomy may still leave some of the limbal epithelium behind10.
The below-described technique will result in LSCD with neovascularization and conjunctivalization that mimics the presentation of complete LSCD in patients and lasts for at least three months1. It is suitable for those who aim to study LSCD or wound healing pathophysiology, immunology, and potential treatments in mice. Possibly, with some modifications, this procedure can be performed in rats or rabbits10. As the rotating burr efficiently removes the epithelium, it can be utilized in any research pertaining to corneal epithelial abrasion/wounding and in any related treatment or molecular biology studies.

<table border="0" cellpadding="0" cellspacing="0" width="1091">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:320px;">&#160;Rotating burr: AlgerBrush II rust ring remover&#160;</td>
			<td style="width:277px;">Rumex International Co, Clearwater, FL</td>
			<td style="width:144px;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; 16-141</td>
			<td style="width:351px;">0.5 mm burr. Also available from other companies.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:320px;">&#160;Surgical microscope</td>
			<td style="width:277px;">Wild Heerbrugg, Switzerland</td>
			<td style="width:144px;">&#160;&#160;&#160;&#160;&#160;&#160; Wild M691</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:320px;">&#160;Digital camera</td>
			<td style="width:277px;">Nikon, Thailand</td>
			<td style="width:144px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:320px;">&#160;Nikon FS-2 slit lamp</td>
			<td style="width:277px;">Nikon, Japan</td>
			<td style="width:144px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:320px;">&#160;Polyclonal anti-CK12 antibody</td>
			<td style="width:277px;">Santa Cruz Blotechnology, CA,</td>
			<td style="width:144px;">&#160;&#160;&#160;&#160;&#160;&#160;&#160; SC-17101</td>
			<td>1:100 concentration</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:320px;">&#160;Monoclonal anti-CK8 antibody</td>
			<td style="width:277px;">TROMA-I-s, Iowa City, IA</td>
			<td style="width:144px;">&#160;&#160;&#160;&#160;&#160;&#160;&#160; AB_531826</td>
			<td>1:50 concentration</td>
		</tr>
	</tbody>
</table>

a simple mechanical procedure to create limbal stem cell deficiency in mouse

Limbal stem cell deficiency (LSCD) is a state of malfunction or loss of limbal epithelial stem cells, after which the corneal epithelium is replaced with conjunctiva. Patients suffer from recurrent corneal defects, pain, inflammation, and loss of vision.
Previously, a murine model of LSCD was described and compared to two other models. The goal was to produce a consistent mouse model of LSCD that both mimics the phenotype in humans and lasts long enough to make it possible to study the disease pathophysiology and to evaluate new treatments. Here, the technique is described in more detail.
A motorized tool with a rotating burr has been designed to remove the rust rings from the corneal surface or to smooth the pterygium bed in patients. It is a suitable device to create the desired LSCD model. It is a readily available, easy-to-use tool with a fine tip that makes it appropriate for working on small eyes, as in mice. Its application prevents unnecessary trauma to the eye and it does not result in unwanted injuries, as often is the case with chemical injury models. As opposed to a blunt scraper, it removes the epithelium with the basement membrane. In this protocol, the limbal area was abraded two times, and then the whole corneal epithelium was shaved from limbus to limbus. To avoid stroma injury, care was taken not to brush the corneal surface once the epithelium was already removed.

Within a month after performing this technique, 100% of the corneas developed superficial neovascularization (Figure 1A. Photos were taken with a camera connected to a slit lamp under a bright field and cobalt blue filter). In 18/20 (90%) of the eyes, neovascularization involved the whole corneal surface (Figure 1A). In 2/20 (10%), neovascularization was observed in three of four corneal quadrants, but it still reached the corneal center.
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Watch this Scientific Journal Video about A Simple Mechanical Procedure to Create Limbal Stem Cell Deficiency in Mouse at JoVE.com

A Simple Mechanical Procedure to Create Limbal Stem Cell Deficiency in Mouse

The following article provides an easy, reproducible technique to effectively create a sustainable mouse model of limbal stem cell deficiency (LSCD). This animal model is useful in testing and comparing the efficacy of treatments for limbal stem cell diseases.

Limbal stem cell deficiency (LSCD) is a state of malfunction or loss of limbal epithelial stem cells, after which the corneal epithelium is replaced with ...

The overall goal of this procedure is to create a reproducible, sustainable, and persistent mouse model of limbal stem cell deficiency. This simple technique provides a consistent animal model of limbal stem cell deficiency, without inducing unwanted injury to the eye, which is difficult to achieve with the standard chemical injury models. This model is useful for studying the disease process in long-term at cellular and molecular level.And for testing or comparing the efficacy of novel treatments. After anesthetizing the mouse, pinch the toe to ensure adequate depth of anesthesia. Inspect the eye under a slit lamp to verify the absence of any previous corneal injury.Instill a drop of 1%tetracaine hydrochloride onto the eye, and wait for 60 seconds. Next, gently apply 5%povidone iodine on the eye and the hair around it. After one minute, wipe off the drop or spread it onto the hair around the eye to prevent the hair from interfering with the tip of the tool.Prepare a sterile rotating burr and a pair of sterile bent tweezers, and keep them on a sterile sheet during the procedure. Now, stabilize the eye by grabbing the lids from the nasal side using the bent tweezers, and gently proctozing the eye. Be careful not to apply too much pressure.Under a surgical microscope, shave around the limbal area twice using the sterile rotating burr. Remove the whole corneal epithelium from limbus to limbus with the rotating burr in a circular fashion, and work with the lateral side of its tip. To avoid stroma injury, do not re-brush corneal parts from which the epithelium has been removed.Do not apply any pressure on the eye. Clean the brush tip as required. Apply a drop of sterile PBS on the cornea, and wipe away any detached epithelial sheets with a soft cleaning tissue.Then, shave the remaining epithelium, if any. Pay attention to the mouse tail to ensure adequate depth of anesthesia during the surgery. Apply a drop of Flourescein sodium onto the cornea.Clean the cornea after 30 seconds, and examine it under a microscope with a cobalt blue filter to verify the complete removal of the epithelium. After the procedure, place the animal in its cage on a heating blanket and observe it for 30-45 minutes until complete recovery from anesthesia. In the meantime, apply 1%Erythromycin Ophthalmic ointment to the eye and continue the application of the antibiotic daily for a week.In addition, inject a 0.1mg/kg of Buprenorphine subcutaneously immediately, and 12 hours after the procedure, and continue the injection twice a day for two days. This is the cornea phenotype one month after the procedure. You can see extensive neovascularization which is a feature of limbal stem cell deficiency.A normal cornea expresses Cytokeratin 12 but is devoid of Cytokeratin 8 or goblet cells. In limbal stem cell deficiency, Cytokeratin 8 and goblet cells appear on the cornea, while Cytokeratin 12 is lost. Once mastered, this technique will result in corneal neovascularization that will cover almost the entire mouse corneal surface in one month, and is stable up to three months.It is important to avoid re-brushing the corneal parts that the epithelium has already been removed. This can cause undesired stroma inflammation and opacification. Following development of limbal stem cell deficiency, experimental treatment methods can be tested and compared.Alternatively, treatments can be started shortly after the injury. This video displayed how to effectively remove the limbal and corneal epithelium to induce limbal stem cell deficiency in mouse. With some modifications, it can be performed on other animals as well.

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Medicine

A Mouse Model of in Utero Transplantation

The transplantation of stem cells and viruses in utero has tremendous potential for treating congenital disorders in the human fetus. For example, in utero transplantation (IUT) of hematopoietic stem cells has been used to successfully treat patients with severe combined immunodeficiency.1,2 In several other conditions, however, IUT has been attempted without success.3 Given these mixed results, the availability of an efficient non-human model to study the biological sequelae of stem cell transplantation and gene therapy is critical to advance this field. We and others have used the mouse model of IUT to study factors affecting successful engraftment of in utero transplanted hematopoietic stem cells in both wild-type mice4-7 and those with genetic diseases.8,9 The fetal environment also offers considerable advantages for the success of in utero gene therapy. For example, the delivery of adenoviral10, adeno-associated viral10, retroviral11, and lentiviral vectors12,13 into the fetus has resulted in the transduction of multiple organs distant from the site of injection with long-term gene expression. in utero gene therapy may therefore be considered as a possible treatment strategy for single gene disorders such as muscular dystrophy or cystic fibrosis. Another potential advantage of IUT is the ability to induce immune tolerance to a specific antigen. As seen in mice with hemophilia, the introduction of Factor IX early in development results in tolerance to this protein.14 
In addition to its use in investigating potential human therapies, the mouse model of IUT can be a powerful tool to study basic questions in developmental and stem cell biology. For example, one can deliver various small molecules to induce or inhibit specific gene expression at defined gestational stages and manipulate developmental pathways. The impact of these alterations can be assessed at various timepoints after the initial transplantation. Furthermore, one can transplant pluripotent or lineage specific progenitor cells into the fetal environment to study stem cell differentiation in a non-irradiated and unperturbed host environment.
The mouse model of IUT has already provided numerous insights within the fields of immunology, and developmental and stem cell biology. In this video-based protocol, we describe a step-by-step approach to performing IUT in mouse fetuses and outline the critical steps and potential pitfalls of this technique.

A Mouse Model of in Utero Transplantation

The mouse model of in utero transplantation is a versatile tool that can be used to study the potential clinical applications of stem cell transplantation and gene therapy in the fetus. In this protocol, we present a general approach to performing this technique

The transplantation of stem cells and viruses in utero has tremendous potential for treating congenital disorders in the human fetus.  For example, in ...

A Simple Method of Mouse Lung Intubation

A simple procedure to intubate mice for pulmonary function measurements would have several advantages in longitudinal studies with limited numbers or expensive animal. One of the reasons that this is not done more routinely is that it is relatively difficult, despite there being several published studies that describe ways to achieve it. In this paper we demonstrate a procedure that eliminates one of the major hurdles associated with this intubation, that of visualizing the trachea during the entire time of intubation. The approach uses a 0.5 mm fiberoptic light source that serves as an introducer to direct the intubation cannula into the mouse trachea. We show that it is possible to use this procedure to measure lung mechanics in individual mice over a time course of at least several weeks. The technique can be set up with relatively little expense and expertise, and it can be routinely accomplished with relatively little training. This should make it possible for any laboratory to routinely carry out this intubation, thereby allowing longitudinal studies in individual mice, thereby minimizing the number of mice needed and increasing the statistical power by using each mouse as its own control.

This paper describes a striaghforward and efficient method of intubating mice for pulmonary function measurements or pulmonary instillation, that allows the mice to recover and be studied at later times. The procedure involves an inexpensive fiberoptic light source that directly illuminates the trachea.

A  simple procedure to intubate mice for pulmonary function measurements would  have several advantages in longitudinal studies with limited numbers or  ...

Parabiosis in Mice: A Detailed Protocol

Parabiosis is a surgical union of two organisms allowing sharing of the blood circulation. Attaching the skin of two animals promotes formation of microvasculature at the site of inflammation. Parabiotic partners share their circulating antigens and thus are free of adverse immune reaction. First described by Paul Bert in 18641, the parabiosis surgery was refined by Bunster and Meyer in 1933 to improve animal survival2. In the current protocol, two mice are surgically joined following a modification of the Bunster and Meyer technique. Animals are connected through the elbow and knee joints followed by attachment of the skin allowing firm support that prevents strain on the sutured skin. Herein, we describe in detail the parabiotic joining of a ubiquitous GFP expressing mouse to a wild type (WT) mouse. Two weeks after the procedure, the pair is separated and GFP positive cells can be detected by flow cytometric analysis in the blood circulation of the WT mouse. The blood chimerism allows one to examine the contribution of the circulating cells from one animal in the other.

Parabiotic joining of two organisms leads to the development of a shared circulatory system. In this protocol, we describe the surgical steps to form a parabiotic connection between a wild-type mouse and a constitutive GFP-expressing mouse.

Parabiosis is a surgical union of two organisms allowing sharing of the blood circulation. Attaching the skin of two animals promotes formation of ...

A Surgical Procedure for Resecting the Mouse Rib: A Model for Large-Scale Long Bone Repair

This protocol introduces researchers to a new model for large-scale bone repair utilizing the mouse rib. The procedure details the following: preparation of the animal for surgery, opening the thoracic body wall, exposing the desired rib from the surrounding intercostal muscles, excising the desired section of rib without inducing a pneumothorax, and closing the incisions. Compared to the bones of the appendicular skeleton, the ribs are highly accessible. In addition, no internal or external fixator is necessary since the adjacent ribs provide a natural fixation. The surgery uses commercially available supplies, is straightforward to learn, and well-tolerated by the animal. The procedure can be carried out with or without removing the surrounding periosteum, and therefore the contribution of the periosteum to repair can be assessed. Results indicate that if the periosteum is retained, robust repair occurs in 1 - 2 months. We expect that use of this protocol will stimulate research into rib repair and that the findings will facilitate the development of new ways to stimulate bone repair in other locations around the body.

The overall goal of this procedure is to successfully resect a portion of bone from the rib of a mouse. The procedure was developed as a model to study large-scale long bone repair.

This protocol introduces researchers to a new model for large-scale bone repair utilizing the mouse rib. The procedure details the following: preparation ...

Studying Pancreatic Cancer Stem Cell Characteristics for Developing New Treatment Strategies

Pancreatic ductal adenocarcinoma (PDAC) contains a subset of exclusively tumorigenic cancer stem cells (CSCs) which have been shown to drive tumor initiation, metastasis and resistance to radio- and chemotherapy. Here we describe a specific methodology for culturing primary human pancreatic CSCs as tumor spheres in anchorage-independent conditions. Cells are grown in serum-free, non-adherent conditions in order to enrich for CSCs while their more differentiated progenies do not survive and proliferate during the initial phase following seeding of single cells. This assay can be used to estimate the percentage of CSCs present in a population of tumor cells. Both size (which can range from 35 to 250 micrometers) and number of tumor spheres formed represents CSC activity harbored in either bulk populations of cultured cancer cells or freshly harvested and digested tumors 1,2. Using this assay, we recently found that metformin selectively ablates pancreatic CSCs; a finding that was subsequently further corroborated by demonstrating diminished expression of pluripotency-associated genes/surface markers and reduced in vivo tumorigenicity of metformin-treated cells. As the final step for preclinical development we treated mice bearing established tumors with metformin and found significantly prolonged survival. Clinical studies testing the use of metformin in patients with PDAC are currently underway (e.g., NCT01210911, NCT01167738, and NCT01488552). Mechanistically, we found that metformin induces a fatal energy crisis in CSCs by enhancing reactive oxygen species (ROS) production and reducing mitochondrial transmembrane potential. In contrast, non-CSCs were not eliminated by metformin treatment, but rather underwent reversible cell cycle arrest. Therefore, our study serves as a successful example for the potential of in vitro sphere formation as a screening tool to identify compounds that potentially target CSCs, but this technique will require further in vitro and in vivo validation to eliminate false discoveries.

Pancreatic cancer stem cells (CSCs) can be expanded in vitro using the anchorage-independent sphere culture technique, which represents a powerful tool to study CSC biology and can serve as the first step to develop novel CSC-targeting therapies. Here the methodology for expanding, analyzing and targeting of pancreatic CSCs is provided.

Pancreatic ductal adenocarcinoma (PDAC) contains a subset of exclusively tumorigenic cancer stem cells (CSCs) which have been shown to drive tumor ...

A Simple Device to Rapidly Prepare Whole Mounts of the Mouse Intestine

Preparing whole mounts of the mouse small intestine and colon for subsequent analysis or quantification can be time consuming and difficult. We describe the use of a simple device to cut and &#8216;roll&#8217; mouse intestines to rapidly prepare whole mount preparations of superior and uniform quality to that which can be achieved by hand. The device comprises a base that holds 4 stainless steel rods and a top, which acts a cutting guide. The rods are inserted into the lumen of the small intestine [divided into thirds] and the colon. The rods and samples are then placed over a piece of filter paper or card into the holding slots in the base of the device. The top of the device is then positioned and serves as a cutting guide. The two angled sections in the center of the top piece are used to guide a knife or scalpel and cut the intestines longitudinally on the top of the rods. Once the intestinal sections have been cut, the top is removed and the card,&#160;tissue and rods gently removed from the device and placed on the bench. The rods are then gently rolled sideways to flatten and stick the intestinal segments onto the underlying piece of filter paper or card. The final preparation can then be examined or fixed and stored for later analysis. The preparations are invaluable for the study of intestinal changes in normal or genetically modified mouse models. The preparations have been used for the study and quantification of the effects of inflammation (colitis), damage, pre-cancerous lesions (aberrant crypt foci (ACFs) and mucin depleted foci (MDFs)) and polyps or tumors.

The use of a simple device to cut and &#8216;roll&#8217; mouse intestines to rapidly prepare whole mount preparations is described.

Preparing whole mounts of the mouse small intestine and colon for subsequent analysis or quantification can be time consuming and difficult. We describe ...

A Neonatal Mouse Spinal Cord Compression Injury Model

Spinal cord injury (SCI) typically causes devastating neurological deficits, particularly through damage to fibers descending from the brain to the spinal cord. A major current area of research is focused on the mechanisms of adaptive plasticity that underlie spontaneous or induced functional recovery following SCI. Spontaneous functional recovery is reported to be greater early in life, raising interesting questions about how adaptive plasticity changes as the spinal cord develops. To facilitate investigation of this dynamic, we have developed a SCI model in the neonatal mouse. The model has relevance for pediatric SCI, which is too little studied. Because neural plasticity in the adult involves some of the same mechanisms as neural plasticity in early life1, this model may potentially have some relevance also for adult SCI. Here we describe the entire procedure for generating a reproducible spinal cord compression (SCC) injury in the neonatal mouse as early as postnatal (P) day 1. SCC is achieved by performing a laminectomy at a given spinal level (here described at thoracic levels 9-11) and then using a modified Yasargil aneurysm mini-clip to rapidly compress and decompress the spinal cord. As previously described, the injured neonatal mice can be tested for behavioral deficits or sacrificed for ex vivo physiological analysis of synaptic connectivity using electrophysiological and high-throughput optical recording techniques1. Earlier and ongoing studies using behavioral and physiological assessment have demonstrated a dramatic, acute impairment of hindlimb motility followed by a complete functional recovery within 2 weeks, and the first evidence of changes in functional circuitry at the level of identified descending synaptic connections1.

This article describes a method for generating a reproducible spinal cord compression injury (SCI) in the neonatal mouse. The model provides an advantageous platform for studying mechanisms of adaptive plasticity that underlie spontaneous functional recovery.

Spinal cord injury (SCI) typically causes devastating neurological deficits, particularly through damage to fibers descending from the brain to the spinal ...

Vein Interposition Model: A Suitable Model to Study Bypass Graft Patency

Bypass grafting is an established treatment method for coronary artery disease. Graft patency continues to be the Achilles heel of saphenous vein grafts. Research models for bypass graft failure are essential for a better understanding of pathobiological and pathophysiological processes during graft patency loss. Large animal models, such as pigs or sheep, resemble human anatomical structures but require special facilities and equipment. This video describes a rat vein interposition model to investigate vein graft patency loss. Rats are inexpensive and easy to handle. Compared to mouse models, the convenient size of rats permits better operability and enables a sufficient amount of material to be obtained for further diverse analysis. In brief, the inferior epigastric vein of a donor rat is harvested and used to replace a segment of the femoral artery. Anastomosis is conducted via single stitches and sealed with fibrin glue. Graft patency can be monitored non-invasively using duplex sonography. Myointimal hyperplasia, which is the main cause for graft patency loss, develops progressively over time and can be calculated from histological cross sections.

This video demonstrates a model to study the development of myointimal hyperplasia after venous interposition surgery in rats.

Bypass grafting is an established treatment method for coronary artery disease. Graft patency continues to be the Achilles heel of saphenous vein grafts. ...

Balloon-based Injury to Induce Myointimal Hyperplasia in the Mouse Abdominal Aorta

The use of animal models is essential for a better understanding of MH, one major cause for arterial stenosis.In this article, we demonstrate a murine balloon denudation model, which is comparable with established vessel injury models in large animals. The aorta denudation model with balloon catheters mimics the clinical setting and leads to comparable pathobiological and physiological changes. Briefly, after performing a horizontal incision in the aorta abdominalis, a balloon catheter will be inserted into the vessel, inflated, and introduced retrogradely. Inflation of the balloon will lead to intima injury and overdistension of the vessel. After removing the catheter, the aortic incision will be closed with single stiches. The model shown in this article is reproducible, easy to perform, and can be established quickly and reliably. It is especially suitable for evaluating expensive experimental therapeutic agents, which can be applied in an economical fashion. By using different knockout-mouse strains, the impact of different genes on MH development can be assessed.

This article demonstrates a murine model to study the development of myointimal hyperplasia (MH) after aortic balloon injury.

The use of animal models is essential for a better understanding of MH, one major cause for arterial stenosis.In this article, we demonstrate a murine ...

Protocol to Create Chronic Wounds in Diabetic Mice

Chronic wounds develop as a result of defective regulation in one or more complex cellular and molecular processes involved in proper healing. They impact ~6.5M people and cost ~$40B/year in the US alone. Although a significant effort has been invested in understanding how chronic wounds develop in humans, fundamental questions remain unanswered. Recently, we developed a novel mouse model for diabetic chronic wounds that have many characteristics of human chronic wounds. Using db/db-/- mice, we can generate chronic wounds by inducing high levels of oxidative stress (OS) in the wound tissue immediately after wounding, using a one-time treatment with inhibitors specific to the antioxidant enzymes catalase and glutathione peroxidase. These wounds have high levels of OS, develop biofilm naturally, become fully chronic within 20 days after treatment and can remain open more for more than 60 days. This novel model has many features of diabetic chronic wounds in humans and therefore can contribute significantly to advancing fundamental understanding of how wounds become chronic. This is a major breakthrough because chronic wounds in humans cause significant pain and distress to patients and result in amputation if unresolved. Moreover, these wounds are very expensive and time-consuming to treat, and lead to significant loss of personal income to patients. Advancements in this field of study through the use of our chronic wound model can significantly improve health care for millions who suffer under this debilitating condition. In this protocol, we describe in great detail the procedure to cause acute wounds to become chronic, which has not been done before.

Chronic wounds are developed from acute wounds on a diabetic mouse model by inducing high levels of oxidative stress after a full-thickness cutaneous wound. The wound is treated with inhibitors for catalase and glutathione peroxidase, resulting in impaired healing and biofilm development by bacteria present in the skin microbiome.

Chronic wounds develop as a result of defective regulation in one or more complex cellular and molecular processes involved in proper healing. They impact ...