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 the toe to confirm the anesthesia depth; the animal should not react.</li>
	<li>Inspect the eye under a slit lamp before conducting the experiments to verify the absence of any previous corneal injury.</li>
	<li>Instill a drop of 1% tetracaine hydrochloride onto the eye. After 60 - 90 sec, test the corneal reflex to confirm the absence of sensation. Proparacaine hydrochloride 0.5% can be used instead.</li>
	<li>When the loss of corneal sensation is certain, gently place a drop of 5% povidone-iodine on the eye and on the hair around the eye. Wipe off the drop after 1 min or spread it on the hair around the eye to prevent the hair from interfering with the tool tip.</li>
</ol>
2. Abrading the Corneal Epithelium
<ol>
	<li>Wear surgical gloves and a gown. Prepare the required tools: a sterile rotating burr and a pair of sterile tweezers. For better control, use bent tweezers. Place the tools on a sterile sheet during the procedure.</li>
	<li>Using the bent tweezers, stabilize the eye by grabbing the lids from the nasal side and gently proptosing the eye. Avoid using too much pressure.</li>
	<li>Under a surgical microscope, shave 360&#176; around the limbal area twice using the sterile rotating burr. Go around the limbus with a speed of 5 - 6 sec per round. 
	NOTE: The burr has one fixed speed. However, for it to rotate at the established speed, the &#34;end nut&#34; should be completely tightened.</li>
	<li>Remove the whole corneal epithelium from limbus to limbus with the rotating burr. For better results, move the tool in a circular fashion and hold it somewhat parallel to the corneal surface to work with the lateral side of its tip. Take care not to injure the stroma by not re-brushing the areas where the epithelium has already been removed. Do not apply any pressure on the eye. Clean the brush tip as required.</li>
	<li>Instill a drop of sterile phosphate-buffered saline on the cornea and wipe away any detached epithelial sheets with a soft cleaning tissue.</li>
	<li>Shave the remaining epithelium, if any.</li>
	<li>Pay attention to the mouse tail during the surgery. 
	NOTE: If any movement occurs, the anesthesia depth has faded and further injection is required. One-third to two-thirds of the primary injected volume should be sufficient. Do not overdose the animal with the anesthetic medication.</li>
	<li>Sterilize all the tools before using them on another eye.</li>
</ol>
3. Confirm Complete Epithelial Removal
<ol>
	<li>Apply a drop of 1 mg/ml fluorescein sodium onto the cornea. Clean the cornea after 30 sec and examine it under a microscope with a cobalt blue filter to verify the complete removal of the epithelium. 
	NOTE: Corneal areas with epithelial defects are visualized in green.</li>
</ol>
4. Post-operation Care
<ol>
	<li>Put the animal on a heating blanket and keep it in a safe place (e.g., in its cage) while under recovery. Do not keep an unconscious animal in the company of conscious ones.</li>
	<li>Apply 1% erythromycin ophthalmic ointment. This will also prevent eye dryness. Continue the application the antibiotic daily for a week.</li>
	<li>Inject 0.1 mg/kg buprenorphine subcutaneously after the procedure and again after 12 hr. Continue the injection twice per day for two days.</li>
	<li>Observe the animal for 30 - 45 min, until complete recovery from anesthesia. 
	NOTE: Mild movement of the respiratory muscles on the ventral surface indicates animal wellness while under recovery.</li>
</ol>

<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. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stem+cell-based+therapy+for+treating+limbal+stem+cells+deficiency:+A+review+of+different+strategies.">Stem cell-based therapy for treating limbal stem cells deficiency: A review of different strategies.</a> Saudi J. Ophthalmol. 28 (3), 188-194 (2014).</li><li>Pal-Ghosh, S., Pajoohesh-Ganji, A., 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=Removal+of+the+basement+membrane+enhances+corneal+wound+healing.">Removal of the basement membrane enhances corneal wound healing.</a> Exp Eye Res. 93 (6), 927-936 (2011).</li><li>Stepp, 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=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. E., Lorca, T., Castro, A., Burgess, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Partial+inhibition+of+Cdk1+in+G+2+phase+overrides+the+SAC+and+decouples+mitotic+events.">Partial inhibition of Cdk1 in G 2 phase overrides the SAC and decouples mitotic events.</a> Cell Cycle. 13, 1400-1412 (2014).</li></ol>

The authors declare that they have nothing to disclose.

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 to assess the outcome of any interventions aimed at the limbal stem cells. An interesting recent study by Li et al.10, which compares the use of the rotating burr with different combinations of surgical and chemical treatments, also found the burr to be safer and more effective in creating LSCD in rabbits. Second, the model seems to be stable for at least up to three months1. Creating this model involves the use of the rotating burr, an instrument that is familiar to clinicians who work with the cornea, as well as to those who do mouse wounding studies. Its advantage over using a blunt spatula is that the injury is more uniform and reproducible1.
To better destroy the limbal stem cells, the limbal area was treated twice. Based on experience working on mouse eyes, treatment of more than two rounds often abrades limbal blood vessels and causes bleeding. In case the technique is used in other animals, this step might be modified depending on the corneal epithelial thickness. In this study, a motorized tool with a 0.5-mm burr tip was utilized; burr tips in other shapes and sizes are also available and can be used instead, depending on corneal specifications and on eye size. Li et al.10 reported the 2.5-mm burr to be suitable to consistently remove rabbit corneal and limbal epithelia.
To obtain the optimal result, limbal and corneal epithelia were shaved in a circular fashion and the lateral side of the burr was used. To prevent the animal hair from interfering with the tool tip, the povidone-iodine drop was spread on the hair around the eye, instead of being wiped off. The tool should not be operated statically in one spot, as this may cause perforation. Treating the limbus at a very slow pace can result in bleeding; a speed of almost 6 sec per round is suitable for a C57BL/6J mouse eye. It is critical to avoid re-brushing the bare stroma, as this will induce more inflammation and stroma opacification. Pressure should not be applied to the eye while abrading the epithelium. After the procedure, the cornea was stained with fluorescein dye to make sure of complete epithelial removal. It is important to prevent eye dryness during animal recovery. Limitations are that this technique cannot remove 100% of the stem cells. It is also somewhat operator-dependent and requires practice to give consistent results.
When studying the corneal epithelial phenotype, whole mount staining is the best way to assess the outcome of this model. This is because it allows the whole corneal epithelium to be evaluated at once, whereas cross sections would only give information about each particular section.
This controllable technique can induce LSCD in mice, and probably in other animals as well. It provides a suitable model of LSCD to study novel treatments and to discover wider aspects of the disease pathophysiology. With some alterations, it can be useful in studying corneal wound healing, angiogenesis, and lymphangiogenesis as well.

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.
To validate the development of LSCD, whole mount immunostaining was performed1. This step is not a part of the protocol and can be altered depending on goals and interests. Three variations were considered as indicators of LSCD: absence of cytokeratin (CK) 12, an intermediate filament specific to normal corneal epithelial cells17, 18; appearance of CK8, a simple epithelia marker20 that is not present on the normal cornea; and presence of goblet cells on the corneal surface. To evaluate the corneal epithelial phenotype, double immunostaining for CK12 and CK8 was performed on whole mount samples three months after the injury, as described previously1, 9. Goblet cell existence was assessed by MUC5AC-goblet cell-specific mucin-immunostaining1, 15, 19 45 days following epithelial removal. The appearance of goblet cells reduces in time. For the best results, it is important to perform the staining less than two months after the injury.
Normal, uninjured corneas express CK12-a specific marker of mature corneal epithelial cells17, 18-throughout the corneal surface, but they are devoid of any CK8 or goblet cells (MUC5AC) on the corneal part of the whole mount samples (Figure 1B). In comparison to normal eyes, CK12 expression is almost absent on injury model corneas, while they significantly show positive staining for CK8 and goblet cells (Figure 1B). These observations indicate the development of LSCD.
If interested in quantifying the immunostaining results, use Image-J to separately quantify20 immunostaining densities on the original, unaltered images taken by the microscope under the same settings. Briefly, select the corneal part of the whole mount sample, measure the integrated density and area for that region, and calculate the corrected density for the background20. The ratio of CK12 to CK8 densities were previously presented on a greater number of samples1. The reduced ratio in comparison to controls (normal corneas) and the appearance of goblet cells on the corneal surface demonstrate the development of LSCD.
<img alt="Figure 1" src="/files/ftp_upload/54658/54658fig1.jpg" /> 
Figure 1: Corneal Phenotype After Creating LSCD in Mice. Slit lamp examination shows that all corneas develop some degree of neovascularization by one month (A, Scale bar: 0.5 mm). A normal cornea expresses CK12 all over the cornea but is devoid of any CK8 or goblet cells (MUC5AC). CK12 is absent in the LSCD model, while CK8 and goblet cells appear on the cornea (B, Scale bar: 200 &#181;m). <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54658/54658fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

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 ...

a-simple-mechanical-procedure-to-create-limbal-stem-cell-deficiency

Nanyang Technological University

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8.3K Views.  University of Illinois at Chicago. 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.

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

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 ...

Myo-mechanical Analysis of Isolated Skeletal Muscle

To assess the in vivo effects of therapeutic interventions for the treatment of muscle disease 1,2,3, quantitative methods are needed that measure force generation and fatigability in treated muscle. We describe a detailed approach to evaluating myo-mechanical properties in freshly explanted hindlimb muscle from the mouse. We describe the atraumatic harvest of mouse extensor digitorum longus muscle, mounting the muscle in a muscle strip myograph (Model 820MS; Danish Myo Technology), and the measurement of maximal twitch and tetanic tension, contraction time, and half-relaxation time, using a square pulse stimulator (Model S48; Grass Technologies). Using these measurements, we demonstrate the calculation of specific twitch and tetanic tension normalized to muscle cross-sectional area, the twitch-to-tetanic tension ratio, the force-frequency relationship curve and the low frequency fatigue curve 4. This analysis provides a method for quantitative comparison between therapeutic interventions in mouse models of muscle disease 1,2,3,5, as well as comparison of the effects of genetic modification on muscle function 6,7,8,9.

To assess the in vivo effects of therapeutic interventions for muscle disease, methods are needed to quantitate force generation and fatigability in treated muscle. We detail an approach to evaluating myo-mechanical properties in explanted mouse hindlimb muscle. This analysis provides a robust approach to quantitating the effects of genetic modification on muscle function, as well as comparison of therapies in mouse models of muscle disease.

To assess the in vivo effects of therapeutic interventions for the treatment of muscle disease 1,2,3, quantitative methods are needed that measure force ...

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. ...

Intranasal Delivery of Therapeutic Stem Cells to Glioblastoma in a Mouse Model

The intrinsic tropism towards brain malignancies renders stem cells as promising carriers of therapeutic agents against malignant tumors. The delivery of therapeutic stem cells via the intranasal route is a recently discovered alternative strategy, with strong potential for clinical translation, due to its non-invasive nature compared to intracranial implantation or delivery via systemic routes. The lack of blood brain barrier further strengthens the therapeutic potential of stem cells undergoing intranasal brain entry. This article summarizes the essential techniques utilized in our studies and outlines the basic principles of intranasal strategy for stem cell delivery using a mouse model of intracranial glioma xenografts. We demonstrate the optimized procedures that generate consistent and reproducible results with specific predetermined experimental parameters and offer guidelines for streamlined work flow that ensure efficient execution and reliable experimental outcome. The article is designed to serve as a baseline for further experimental customization based on hypothesis, stem cell types, or tumor specifics.

Stem cells are promising therapeutic carriers to treat brain tumors due to their intrinsic tumor tropism. Non-invasive intranasal stem cell delivery bypasses the blood brain barrier and demonstrates strong potential for clinical translation. This article summarizes the basic principles of intranasal stem cell delivery in a mouse model of glioma.

The intrinsic tropism towards brain malignancies renders stem cells as promising carriers of therapeutic agents against malignant tumors. The delivery of ...

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

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Chapters in this video

A Mouse Model of in Utero Transplantation

Myo-mechanical Analysis of Isolated Skeletal Muscle

A Simple Method of Mouse Lung Intubation

Parabiosis in Mice: A Detailed Protocol

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

Studying Pancreatic Cancer Stem Cell Characteristics for Developing New Treatment Strategies

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

A Neonatal Mouse Spinal Cord Compression Injury Model

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

Intranasal Delivery of Therapeutic Stem Cells to Glioblastoma in a Mouse Model