We sincerely thank Shin-Han Tseng for the critical discussion and partial execution of the study. This study was supported by EDAHP110003 and NCKUEDA110002 from the Research Foundation of E-DA Hospital and the National Cheng Kung University, Taiwan.

All mouse experiments were approved by the Laboratory Animal Center of the E-DA Hospital/ I-Shou University and were handled according to the &#34;Guide for the Care and Use of Laboratory Animals&#34; (NRC, USA 2011). Male C57BL/6 mice, 7-8 weeks old, were used for the present study.
1. Chemical preparation
<ol>
	<li>Prepare the chemical irritant by diluting 0.1% chlorhexidine gluconate (CG, see Table of Materials) in 15% ethanol.</li>
</ol>
2. Animal treatment
<ol>
	<li>Assign three mice as the control group. Perform intraperitoneal injection (i.p.) of 1 mL/kg of 0.9% normal saline (NS) every other day for 3 weeks, for a total of nine times.</li>
	<li>Assign three mice to the peritoneal fibrosis group. Induce peritoneal fibrosis using chlorhexidine gluconate (CG) by administering i.p. injections of 0.1% of CG in 15% ethanol (step 1.1) at a dose of 12.5 &#181;L/g body weight. Perform this every other day for 3 weeks, for a total of nine times.</li>
</ol>
3. Peritoneal function tests (modified peritoneal equilibration test)
<ol>
	<li>Prepare a dialysis solution containing 4.25% glucose. Draw 0.5 mL of dialysate sample with a syringe, and then check the glucose concentration in the dialysate sample. 
	NOTE: The glucose concentration is determined according to the hexokinase/G6PD method. Dialysate samples were accessed to L-type Glu 2 assay and investigated with a biochemical analyzer (see Table of Materials). This is the initial dialysate glucose concentration.</li>
	<li>Anesthetize the mice by intramuscular injection of Zoletil and Xylazine (prepared in a ratio of 1:2 by volume, see Table of Materials) at a dose of 20 &#181;L/20 gw. Additionally, use vet ointment on the eyes to prevent dryness under anesthesia.</li>
	<li>Perform i.p. instillation of the dialysis solution (2 mL/20 g bodyweight).</li>
	<li>After 30 min, assess and verify the depth of anesthesia with lack of toe pinch reflex. Then, perform a vertical incision in the midline of the abdominal (beneath the xiphoid process), then open the mice&#39;s abdomen and collect the intraperitoneal fluid with a syringe (defined as &#34;volume 1&#34;). Then, measure the weight of a clean and dry cotton and put the cotton into the mice&#39;s abdominal cavity to absorb the residual intraperitoneal fluid. Finally, measure the cotton weight again. 
	NOTE: The weight gain of cotton is equal to the weight of the residual intraperitoneal fluid. Then, convert to the obtained volume (specific gravity: 1 g/cm3; defined as &#34;volume 2&#34;). The final dialysate volume is volume 1 plus volume 2.</li>
	<li>Use 0.5 mL of dialysate sample (final dialysate) to measure the glucose concentration. This is the final dialysate glucose concentration.</li>
	<li>Calculate the net ultrafiltration using the formula15: 
	<img alt="Equation 1" src="/files/ftp_upload/63903/63903eq01.jpg" style="margin: auto;" /></li>
	<li>Calculate the peritoneal permeability using the following formula15: 
	<img alt="Equation 2" src="/files/ftp_upload/63903/63903eq02.jpg" style="margin: auto;" /></li>
</ol>
4. Tissue preparation of the abdominal wall muscle and liver and histological analysis
<ol>
	<li>Sacrifice the mice via cardiac puncture (phlebotomy)3,16.</li>
	<li>Cut the abdominal wall (1 cm x 1 cm) and total hepatectomy. Fix the mice&#39;s abdominal wall and liver tissues overnight in 10% neutral buffered formalin.</li>
	<li>Prepare 3 &#181;m thick paraffin sections of the abdominal wall muscle and liver, and perform histological analysis following previously published report17.</li>
	<li>Evaluate the parietal peritoneum of the abdominal wall and visceral peritoneum of the liver surfaces of the mice using morphometry18.</li>
	<li>Perform statistical analyses using statistics and graphing software (see Table of Materials). Express all data as mean &#177; SD and analyze for statistical significance using a t-test19. Define values with P &#60; 0.05 as significant results.</li>
</ol>

<ol>
	<li>Han, S. 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=Improving+outcome+of+CAPD:+twenty-five+years'+experience+in+a+single+Korean+center.">Improving outcome of CAPD: twenty-five years' experience in a single Korean center.</a> Peritoneal Dialysis International. 27 (4), 432-440 (2007).</li><li>Kawaguchi, Y., Hasegawa, T., Nakayama, M., Kubo, H., Shigematu, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Issues+affecting+the+longevity+of+the+continuous+peritoneal+dialysis+therapy.">Issues affecting the longevity of the continuous peritoneal dialysis therapy.</a> Kidney International Supplements. 62, 105-107 (1997).</li><li>Lee, Y. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vitamin+D+can+ameliorate+chlorhexidine+gluconate-induced+peritoneal+fibrosis+and+functional+deterioration+through+the+inhibition+of+epithelial-to-mesenchymal+transition+of+mesothelial+cells.">Vitamin D can ameliorate chlorhexidine gluconate-induced peritoneal fibrosis and functional deterioration through the inhibition of epithelial-to-mesenchymal transition of mesothelial cells.</a> BioMed Research International. 2015, 595030 (2015).</li><li>Nakamoto, H., Kawaguchi, Y., Suzuki, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Is+technique+survival+on+peritoneal+dialysis+better+in+Japan.">Is technique survival on peritoneal dialysis better in Japan.</a> Peritoneal Dialysis International. 26 (2), 136-143 (2006).</li><li>Schaefer, F., Klaus, G., Muller-Wiefel, D. E., Mehls, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Current+practice+of+peritoneal+dialysis+in+children:+results+of+a+longitudinal+survey.+Mid+European+Pediatric+Peritoneal+Dialysis+Study+Group+(MEPPS).">Current practice of peritoneal dialysis in children: results of a longitudinal survey. Mid European Pediatric Peritoneal Dialysis Study Group (MEPPS).</a> Peritoneal Dialysis International. 19, 445-449 (1999).</li><li>Woodrow, G., Turney, J. H., Brownjohn, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Technique+failure+in+peritoneal+dialysis+and+its+impact+on+patient+survival.">Technique failure in peritoneal dialysis and its impact on patient survival.</a> Peritoneal Dialysis International. 17 (4), 360-364 (1997).</li><li>Schmidt, D. W., Flessner, M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pathogenesis+and+treatment+of+encapsulating+peritoneal+sclerosis:+basic+and+translational+research.">Pathogenesis and treatment of encapsulating peritoneal sclerosis: basic and translational research.</a> Peritoneal Dialysis International. 28, 10-15 (2008).</li><li>Augustine, T., Brown, P. W., Davies, S. D., Summers, A. M., Wilkie, M. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Encapsulating+peritoneal+sclerosis:+clinical+significance+and+implications.">Encapsulating peritoneal sclerosis: clinical significance and implications.</a> Nephron Clinical Practice. 111 (2), 149-154 (2009).</li><li>Di Paolo, N., Nicolai, G. A., Garosi, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+peritoneum:+from+histological+studies+to+mesothelial+transplant+through+animal+experimentation.">The peritoneum: from histological studies to mesothelial transplant through animal experimentation.</a> Peritoneal Dialysis International. 28, 5-9 (2008).</li><li>Fusshoeller, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Histomorphological+and+functional+changes+of+the+peritoneal+membrane+during+long-term+peritoneal+dialysis.">Histomorphological and functional changes of the peritoneal membrane during long-term peritoneal dialysis.</a> Pediatric Nephrology. 23 (1), 19-25 (2008).</li><li>Goffin, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Peritoneal+membrane+structural+and+functional+changes+during+peritoneal+dialysis.">Peritoneal membrane structural and functional changes during peritoneal dialysis.</a> Seminars in Dialysis. 21 (3), 258-265 (2008).</li><li>Ito, T., Yorioka, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Peritoneal+damage+by+peritoneal+dialysis+solutions.">Peritoneal damage by peritoneal dialysis solutions.</a> Clinical and Experimental Nephrology. 12 (4), 243-249 (2008).</li><li>Io, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=SAHA+suppresses+peritoneal+fibrosis+in+mice.">SAHA suppresses peritoneal fibrosis in mice.</a> Peritoneal Dialysis International. 35 (3), 246-258 (2015).</li><li>Yoh, K., Ojima, M., Takahashi, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Th2-biased+GATA-3+transgenic+mice+developed+severe+experimental+peritoneal+fibrosis+compared+with+Th1-biased+T-bet+and+Th17-biased+RORgammat+transgenic+mice.">Th2-biased GATA-3 transgenic mice developed severe experimental peritoneal fibrosis compared with Th1-biased T-bet and Th17-biased RORgammat transgenic mice.</a> Experimental Animals. 64 (4), 353-362 (2015).</li><li>Karl, Z. J. T., 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=Peritoneal+Equilibration+Test.">Peritoneal Equilibration Test.</a> Peritoneal Dialysis International. 7 (3), 138-148 (1987).</li><li>Lee, Y. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+clinical+implication+of+vitamin+D+nanomedicine+for+peritoneal+dialysis-related+peritoneal+damage.">The clinical implication of vitamin D nanomedicine for peritoneal dialysis-related peritoneal damage.</a> International Journal of Nanomedicine. 14, 9665-9675 (2019).</li><li>Goldner, 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=Modification+of+the+masson+trichrome+technique+for+routine+laboratory+purposes.">Modification of the masson trichrome technique for routine laboratory purposes.</a> The American Journal of Pathology. 14 (2), 237-243 (1938).</li><li>Cheng, F. 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=Novel+application+of+magnetite+nanoparticle-mediated+vitamin+D3+delivery+for+peritoneal+dialysis-related+peritoneal+damage.">Novel application of magnetite nanoparticle-mediated vitamin D3 delivery for peritoneal dialysis-related peritoneal damage.</a> International Journal of Nanomedicine. 16, 2137-2146 (2021).</li><li>Ross, A., Willson, V. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Basic and Advanced Statistical Tests: Writing Results Sections and Creating Tables and Figures. , 13-16 (2017).</li><li>Suga, 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=Preventive+effect+of+pirfenidone+against+experimental+sclerosing+peritonitis+in+rats.">Preventive effect of pirfenidone against experimental sclerosing peritonitis in rats.</a> Experimental and Toxicologic Pathology. 47 (4), 287-291 (1995).</li><li>Ishii, 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=An+experimental+sclerosing+encapsulating+peritonitis+model+in+mice.">An experimental sclerosing encapsulating peritonitis model in mice.</a> Nephrology Dialysis Transplantation. 16 (6), 1262-1266 (2001).</li><li>Nishino, T., 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=Antisense+oligonucleotides+against+collagen-binding+stress+protein+HSP47+suppress+peritoneal+fibrosis+in+rats.">Antisense oligonucleotides against collagen-binding stress protein HSP47 suppress peritoneal fibrosis in rats.</a> Kidney International. 64 (3), 887-896 (2003).</li><li>Mishima, 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=Enhanced+expression+of+heat+shock+protein+47+in+rat+model+of+peritoneal+fibrosis.">Enhanced expression of heat shock protein 47 in rat model of peritoneal fibrosis.</a> Peritoneal Dialysis International. 23 (1), 14-22 (2003).</li><li>Kushiyama, T., 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+liposome-encapsulated+clodronate+on+chlorhexidine+gluconate-induced+peritoneal+fibrosis+in+rats.">Effects of liposome-encapsulated clodronate on chlorhexidine gluconate-induced peritoneal fibrosis in rats.</a> Nephrology Dialysis Transplantation. 26 (10), 3143-3154 (2011).</li><li>Nishino, T., 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=Involvement+of+lymphocyte+infiltration+in+the+progression+of+mouse+peritoneal+fibrosis+model.">Involvement of lymphocyte infiltration in the progression of mouse peritoneal fibrosis model.</a> Renal Failure. 34 (6), 760-766 (2012).</li><li>Lua, I., Li, Y., Pappoe, L. S., Asahina, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myofibroblastic+conversion+and+regeneration+of+mesothelial+cells+in+peritoneal+and+liver+fibrosis.">Myofibroblastic conversion and regeneration of mesothelial cells in peritoneal and liver fibrosis.</a> The American Journal of Pathology. 185 (12), 3258-3273 (2015).</li><li>Kitamura, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epigallocatechin+gallate+suppresses+peritoneal+fibrosis+in+mice.">Epigallocatechin gallate suppresses peritoneal fibrosis in mice.</a> Chemico-Biological Interactions. 195 (1), 95-104 (2012).</li></ol>

The authors have nothing to disclose.

In this study, a mouse PD model is presented by i.p. injection of CG, and the results showed peritoneal fibrosis and functional deterioration in this model, which mimicked the PD patient&#39;s condition.
There are several critical steps in the protocol. First, for performing an i.p. injection of CG or NS, the abdominal wall skin of the mouse must be picked up using forceps to prevent puncture-induced intraperitoneal organ damage. Second, while collecting the peritoneum of the abdominal wall fo...

Peritoneal dialysis (PD) is a type of renal replacement therapy. However, PD has problems that cannot be solved. For example, long-term PD treatment can cause peritoneal damage, eventually leading to ultrafiltration failure and withdrawal of treatment1,2,3,4,5,6. Peritoneal fibrosis is one of the most serious complications7,8. Peritoneal fibrosis is characterized by the deposition and accumulation of extracellular matrix within the interstitium, and neo-angiogenesis and vasculopathy of the peritoneum9,10.
The main causes of these peritoneal changes are recurrent peritonitis and non-biocompatibility of the dialysate, which are hyperosmotic, high glucose, low pH, and glucose degradation product accumulation11,12. Therefore, suitable animal experimental models can help researchers better study the peritoneum&#39;s physiological and pathological changes during PD therapy. Therefore, establishing an animal PD model is important for improving PD technology and dialysis efficacy and prolonging patient survival. This study aimed to generate a PD mouse model by intraperitoneal (i.p.) injection of chlorhexidine gluconate (CG), as described previously13,14. This PD mouse model is simple, easy to use, and feasible compared to other PD animal models.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>0.9% Normal Saline</td>
			<td>Y F CHEMICAL CORP., New Taipei City, Taiwan</td>
			<td>-</td>
			<td></td>
		</tr>
		<tr>
			<td>10% neutral buffered formalin</td>
			<td>Taiwan Burnett International Co., Ltd., Taipei City, Taiwan</td>
			<td>00002A</td>
			<td></td>
		</tr>
		<tr>
			<td>Automatic biochemical analyzer</td>
			<td>Hitachi Ltd., Tokyo, Japan</td>
			<td>Labospect Series 008</td>
			<td>for determining glucose concentration</td>
		</tr>
		<tr>
			<td>Chlorhexidine digluconate solution, 20% in H2O</td>
			<td>Sigma-Aldrich, MO, USA</td>
			<td>C9394</td>
			<td>diluted to 0.1% with 15% ethanol for injection</td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Avantor Performance Materials, LLC, PA, USA</td>
			<td>BAKR8006-05</td>
			<td>diluted to 15% with normal saline for working concentration</td>
		</tr>
		<tr>
			<td>Glucose (Dianeal)</td>
			<td>Baxter International, Inc., IL, USA</td>
			<td>FNB9896</td>
			<td>Commercial dialysis solution (4.25%)</td>
		</tr>
		<tr>
			<td>GraphPad Prism 8.0</td>
			<td>GraphPad Software, Inc., CA, US</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>L-type Glu 2 assay</td>
			<td>FUJIFILM Wako, Japan</td>
			<td>461-32403</td>
			<td></td>
		</tr>
		<tr>
			<td>Xylazine 20</td>
			<td>Juily Pharmaceutical Co., Ltd., New Taipei City, Taiwan</td>
			<td>-</td>
			<td></td>
		</tr>
		<tr>
			<td>Zoletil 50</td>
			<td>Virbac Laboratories, Carros, France</td>
			<td>-</td>
			<td></td>
		</tr>
	</tbody>
</table>

a mice model of chlorhexidine gluconate-induced peritoneal damage

Peritoneal fibrosis is an important complication of peritoneal dialysis (PD). To investigate and address this problem, an appropriate animal model of PD is required. The present protocol establishes a chlorhexidine gluconate (CG) induced peritoneal fibrosis model that mimics the condition of a patient with PD. Peritoneal fibrosis was induced by intraperitoneal injection of 0.1% of CG in 15% ethanol for 3 weeks (administered every other day), for a total of nine times in male C57BL/6 mice. Peritoneal functional tests were then performed on day 22. After the mice were sacrificed, the parietal peritoneum of the abdominal wall and the visceral peritoneum of the liver were harvested. They were thicker and more fibrotic when analyzed microscopically after Masson's trichrome staining. The ultrafiltration rate decreased, and glucose mass transport indicated a CG-induced increase in peritoneal permeability. The PD model thus established may have applications in improving PD technology, dialysis efficacy, and prolonging patient survival.

In Figure 1A,B, the parietal peritoneum of the abdominal wall was markedly thicker and more fibrotic under Masson&#39;s trichrome staining17, indicating that in the CG-exposed group, peritoneal fibrosis is more severe than in the control saline group (NS). In Figure 2A,B, the visceral peritoneum of the liver surfaces was also markedly thicker and more fibrotic, thus proving that in the CG-exposed group, p...

Watch this Scientific Journal Video about A Mice Model of Chlorhexidine Gluconate-Induced Peritoneal Damage at JoVE.com

A Mice Model of Chlorhexidine Gluconate-Induced Peritoneal Damage

The present protocol establishes a peritoneal dialysis (PD) mouse model of chlorhexidine gluconate (CG)-induced peritoneal fibrosis. The current model is simple and easy to use compared to other PD animal models.

Peritoneal fibrosis is an important complication of peritoneal dialysis (PD). To investigate and address this problem, an appropriate animal model of PD ...

a-mice-model-of-chlorhexidine-gluconate-induced-peritoneal-damage

Research

JoVE Journal

Medicine

1.7K Views.  I-Shou University. The present protocol establishes a peritoneal dialysis (PD) mouse model of chlorhexidine gluconate (CG)-induced peritoneal fibrosis. The current model is simple and easy to use compared to other PD animal models.

Video: A Mice Model of Chlorhexidine Gluconate-Induced Peritoneal Damage

Tibial Nerve Transection - A Standardized Model for Denervation-induced Skeletal Muscle Atrophy in Mice

The tibial nerve transection model is a well-tolerated, validated, and reproducible model of denervation-induced skeletal muscle atrophy in rodents. Although originally developed and used extensively in the rat due to its larger size, the tibial nerve in mice is big enough that it can be easily manipulated with either crush or transection, leaving the peroneal and sural nerve branches of the sciatic nerve intact and thereby preserving their target muscles. Thus, this model offers the advantages of inducing less morbidity and impediment of ambulation than the sciatic nerve transection model and also allows investigators to study the physiologic, cellular and molecular biologic mechanisms regulating the process of muscle atrophy in genetically engineered mice. The tibial nerve supplies the gastrocnemius, soleus and plantaris muscles, so its transection permits the study of denervated skeletal muscle composed of fast twitch type II fibers and/or slow twitch type I fibers. Here we demonstrate the tibial nerve transection model in the C57Black6 mouse. We assess the atrophy of the gastrocnemius muscle, as a representative muscle, at 1, 2, and 4 weeks post-denervation by measuring muscle weights and fiber type specific cross-sectional area on paraffin-embedded histologic sections immunostained for fast twitch myosin.

The tibial nerve transection model is a well-tolerated, validated, and reproducible model of skeletal muscle atrophy. The model surgical protocol is described and demonstrated in C57Black6 mice. &#160;

The tibial nerve transection model is a well-tolerated, validated, and reproducible model of denervation-induced skeletal muscle atrophy in rodents. ...

A Simple Critical-sized Femoral Defect Model in Mice

While bone has a remarkable capacity for regeneration, serious bone trauma often results in damage that does not properly heal. In fact, one tenth of all limb bone fractures fail to heal completely due to the extent of the trauma, disease, or age of the patient. Our ability to improve bone regenerative strategies is critically dependent on the ability to mimic serious bone trauma in test animals, but the generation and stabilization of large bone lesions is technically challenging. In most cases, serious long bone trauma is mimicked experimentally by establishing a defect that will not naturally heal. This is achieved by complete removal of a bone segment that is larger than 1.5 times the diameter of the bone cross-section. The bone is then stabilized with a metal implant to maintain proper orientation of the fracture edges and allow for mobility. 
Due to their small size and the fragility of their long bones, establishment of such lesions in mice are beyond the capabilities of most research groups. As such, long bone defect models are confined to rats and larger animals. Nevertheless, mice afford significant research advantages in that they can be genetically modified and bred as immune-compromised strains that do not reject human cells and tissue.
Herein, we demonstrate a technique that facilitates the generation of a segmental defect in mouse femora using standard laboratory and veterinary equipment. With practice, fabrication of the fixation device and surgical implantation is feasible for the majority of trained veterinarians and animal research personnel. Using example data, we also provide methodologies for the quantitative analysis of bone healing for the model.

Animal models are frequently employed to mimic serious bone injury in biomedical research. Due to their small size, establishment of stabilized bone lesions in mice are beyond the capabilities of most research groups. Herein, we describe a simple method for establishing and analyzing experimental femoral defects in mice.

While bone has a remarkable capacity for regeneration, serious bone trauma often results in damage that does not properly heal. In fact, one tenth of all ...

Quantitation of Intra-peritoneal Ovarian Cancer Metastasis

Epithelial ovarian cancer (EOC) is the leading cause of death from gynecologic malignancy in the United States. Mortality is due to diagnosis of 75% of women with late stage disease, when metastasis is already present. EOC is characterized by diffuse and widely disseminated intra-peritoneal metastasis. Cells shed from the primary tumor anchor in the mesothelium that lines the peritoneal cavity as well as in the omentum, resulting in multi-focal metastasis, often in the presence of peritoneal ascites. Efforts in our laboratory are directed at a more detailed understanding of factors that regulate EOC metastatic success. However, quantifying metastatic tumor burden represents a significant technical challenge due to the large number, small size and broad distribution of lesions throughout the peritoneum. Herein we describe a method for analysis of EOC metastasis using cells labeled with red fluorescent protein (RFP) coupled with in vivo multispectral imaging. Following intra-peritoneal injection of RFP-labelled tumor cells, mice are imaged weekly until time of sacrifice. At this time, the peritoneal cavity is surgically exposed and organs are imaged in situ. Dissected organs are then placed on a labeled transparent template and imaged ex vivo. Removal of tissue auto-fluorescence during image processing using multispectral unmixing enables accurate quantitation of relative tumor burden. This method has utility in a variety of applications including therapeutic studies to evaluate compounds that may inhibit metastasis and thereby improve overall survival.

Ovarian cancer metastasis is characterized by numerous diffuse intra-peritoneal lesions, such that accurate visual quantitation of tumor burden is challenging. Herein we describe a method for in situ and ex vivo quantitation of metastatic tumor burden using red fluorescent protein (RFP)-labeled tumor cells and optical imaging.

Epithelial ovarian cancer (EOC) is the leading cause of death from gynecologic malignancy in the United States.  Mortality is due to diagnosis of 75% of ...

A Magnetic Microbead Occlusion Model to Induce Ocular Hypertension-Dependent Glaucoma in Mice

The use of rodent models of glaucoma has been essential to understand the molecular mechanisms that underlie the pathophysiology of this multifactorial neurodegenerative disease. With the advent of numerous transgenic mouse lines, there is increasing interest in inducible murine models of ocular hypertension. Here, we present an occlusion model of glaucoma based on the injection of magnetic microbeads into the anterior chamber of the eye using a modified microneedle with a facetted bevel. The magnetic microbeads are attracted to the iridocorneal angle using a handheld magnet to block the drainage of aqueous humour from the anterior chamber. This disruption in aqueous dynamics results in a steady elevation of intraocular pressure, which subsequently leads to the loss of retinal ganglion cells, as observed in human glaucoma patients. The microbead occlusion model presented in this manuscript is simple compared to other inducible models of glaucoma and also highly effective and reproducible. Importantly, the modifications presented here minimize common issues that often arise in occlusion models. First, the use of a bevelled glass microneedle prevents backflow of microbeads and ensures that minimal damage occurs to the cornea during the injection, thus reducing injury-related effects. Second, the use of magnetic microbeads ensures the ability to attract most beads to the iridocorneal angle, effectively reducing the number of beads floating in the anterior chamber avoiding contact with other structures (e.g., iris, lens). Lastly, the use of a handheld magnet allows flexibility when handling the small mouse eye to efficiently direct the magnetic microbeads and ensure that there is little reflux of the microbeads from the eye when the microneedle is withdrawn. In summary, the microbead occlusion mouse model presented here is a powerful investigative tool to study neurodegenerative changes that occur during the onset and progression of glaucoma.

Here, we present a protocol to induce ocular hypertension in the murine eye that results in the loss of retinal ganglion cells as observed in glaucoma. Magnetic microbeads are injected into the anterior chamber and attracted to the iridocorneal angle using a magnet to block the outflow of aqueous humour.

The use of rodent models of glaucoma has been essential to understand the molecular mechanisms that underlie the pathophysiology of this multifactorial ...

Myocardial Infarction in Neonatal Mice, A Model of Cardiac Regeneration

Myocardial infarction induced by coronary artery ligation has been used in many animal models as a tool to study the mechanisms of cardiac repair and regeneration, and to define new targets for therapeutics. For decades, models of complete heart regeneration existed in amphibians and fish, but a mammalian counterpart was not available. The recent discovery of a postnatal window during which mice possess regenerative capabilities has led to the establishment of a mammalian model of cardiac regeneration. A surgical model of mammalian cardiac regeneration in the neonatal mouse is presented herein. Briefly, postnatal day 1 (P1) mice are anesthetized by isoflurane and placed on an ice pad to induce hypothermia. After the chest is opened, and the left anterior descending coronary artery (LAD) is visualized, a suture is placed around the LAD to inflict myocardial ischemia in the left ventricle. The surgical procedure takes 10-15 min. Visualizing the coronary artery is crucial for accurate suture placement and reproducibility. Myocardial infarction and cardiac dysfunction are confirmed by triphenyl-tetrazolium chloride (TTC) staining and echocardiography, respectively. Complete regeneration 21 days post myocardial infarction is verified by histology. This protocol can be used to as a tool to elucidate mechanisms of mammalian cardiac regeneration after myocardial infarction.

This protocol describes a highly reproducible model of cardiac regeneration by surgical induction of myocardial infarction in the left ventricle of postnatal day 1 mice. The method involves induction of hypothermic anesthesia and ligation of the left anterior descending coronary artery.

Myocardial infarction induced by coronary artery ligation has been used in many animal models as a tool to study the mechanisms of cardiac repair and ...

A Repetitive Concussive Head Injury Model in Mice

Despite the concussion/ mild traumatic brain injury (mTBI) being the most frequent occurrence of traumatic brain injury, there is still a lack of knowledge on the injury and its effects. To develop a better understanding of concussions, animals are often used because they provide a controlled, rigorous, and efficient model. Studies have adapted traditional animal models to perform mTBI to stimulate mild injury severity by changing the injury parameters. These models have been used because they can produce morphologically similar brain injuries to the clinical condition and provide a spectrum of injury severities. However, they are limited in their ability to present the identical features of injuries in patients. Using a traditional impact system, a repetitive concussive injury (rCHI) model can induce mild to moderate human-like concussion. The injury degree can be determined by measuring the period of loss of consciousness (LOC) with a sign of a transient termination of breathing. The rCHI model is beneficial to use for its accuracy and simplicity in determining mTBI effects and potential treatments.

Concussion presents the most common type of traumatic brain injury. Therefore, a repetitive concussive animal model, which replicates the important features of an injury in patients, may provide a means to study concussion in a rigorous, controlled, and efficient manner.

Despite the concussion/ mild traumatic brain injury (mTBI) being the most frequent occurrence of traumatic brain injury, there is still a lack of ...

Induction of Accelerated Atherosclerosis in Mice: The "Wire-Injury" Model

Atherosclerosis is a proliferative fibro-inflammatory disease developing in the arterial wall, inducing a deficient blood flow or a lack of blood flow. Moreover, by rupture of the defective vascular wall, atherosclerosis induces occlusive thrombus formation, which represents the main cause of myocardial infarction or stroke and the most frequent cause of death. Despite the advances in the cardiovascular field, many questions remain unanswered, and additional basic research is essential to improve our understanding of the molecular mechanisms during atherosclerosis and its effects. Due to limited clinical studies, there is a need for representative animal models recreating atherosclerotic conditions such as neointima formation after stent implantation, balloon angioplasty, or endarterectomy. Since the mouse presents many advantages and is the most frequently used model for studying molecular processes, the current study proposes an invasive procedure of endothelial denudation, also known as the wire-injury model, which is representative of the human condition of neointima formation in arteries after revascularization procedures.

This study describes an invasive procedure for the induction of accelerated atherosclerosis in mice. In comparison to other methods using electric- or cryo-induced injury, mechanical-induced injury mimics the human condition of restenosis after revascularization therapies and is ideal for the study of the molecular mechanisms involved.

Atherosclerosis is a proliferative fibro-inflammatory disease developing in the arterial wall, inducing a deficient blood flow or a lack of blood flow. ...

Isometric Contractility Measurement of the Mouse Mesenteric Artery Using Wire Myography

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and drugs. It is widely used in many studies on the physiological functions of vascular smooth muscle, the pathogenesis of vascular diseases such as hypertension, and the development of smooth muscle relaxant drugs. The mouse is a widely used model animal with a large pool of disease models and genetically modified strains. We introduced this method to measure the isometric contraction of mouse mesenteric artery in detail. A 1.4-mm segment of mouse mesenteric resistance artery was isolated and mounted on a myograph chamber by passing two steel wires through its lumen. After equilibration and normalization steps, the vessel segment was potentiated by a high-K+ solution twice prior to the contraction assay. As an example of the application of this method in drug development, we measured the relaxant effect of a novel natural substance, neoliensinine, isolated from a Chinese herb, embryos of the lotus seed (Nelumbo nucifera Gaertn.) on mouse mesenteric arteries. The vessel segments mounted on the myograph chamber were stimulated with a high-K+ solution. When the force tension reached a stable sustained phase, cumulative doses of neoliensinine were added to the chamber. We found that neoliensinine had a dose-dependent relaxant effect on smooth muscle contraction, thus suggesting that it bears potential activity against hypertension. In addition, as the vessel segment can survive at least 4 hours after mounting and maintain contractility induced by the high-K+ solution for many times, we suggest that the wire myograph system may be used for the time-consuming process of drug screening.

The wire myograph technique is used to investigate vascular smooth muscle functions and screen new drugs. We report a detailed protocol for measuring the isometric contractility of the mouse mesenteric artery and for screening new relaxants of vascular smooth muscle.

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and ...

A Model of Glaucoma Induced by Circumlimbal Suture in Rats and Mice

The circumlimbal suture is a technique for inducing experimental glaucoma in rodents by chronically elevating intraocular pressure (IOP), a well-known risk factor for glaucoma. This protocol demonstrates a step-by-step guide on this technique in Long Evans rats and C57BL/6 mice. Under general anesthesia, a "purse-string" suture is applied on the conjunctiva, around the equator and behind the limbus of the eye. The fellow eye serves as an untreated control. Over the duration of our study, which was a period of 8 weeks for rats and 12 weeks for mice, IOP remained elevated, as measured regularly by rebound tonometry in conscious animals without topical anesthesia. In both species, the sutured eyes showed electroretinogram features consistent with preferential inner retinal dysfunction. Optical coherence tomography showed selective thinning of the retinal nerve fiber layer. Histology of the rat retina in cross-section found reduced cell density in the ganglion cell layer, but no change in other cellular layers. Staining of flat-mounted mouse retinae with a ganglion cell specific marker (RBPMS) confirmed ganglion cell loss. The circumlimbal suture is a simple, minimally invasive and cost-effective way to induce ocular hypertension that leads to ganglion cell injury in both rats and mice.

Chronic ocular hypertension is induced by applying a circumlimbal suture in rats and mice, leading to functional and structural deterioration of the retinal ganglion cells consistent with glaucoma.

The circumlimbal suture is a technique for inducing experimental glaucoma in rodents by chronically elevating intraocular pressure (IOP), a well-known ...

A Reversible Silicon Oil-Induced Ocular Hypertension Model in Mice

Elevated intraocular pressure (IOP) is a well-documented risk factor for glaucoma. Here we describe a novel, effective method for consistently inducing stable IOP elevation in mice that mimics the post-operative complication of using silicone oil (SO) as a tamponade agent in human vitreoretinal surgery. In this protocol, SO is injected into the anterior chamber of the mouse eye to block the pupil and prevent inflow of aqueous humor. The posterior chamber accumulates aqueous humor and this in turn increases the IOP of the posterior segment. A single SO injection produces reliable, sufficient, and stable IOP elevation, which induces significant glaucomatous neurodegeneration. This model is a true replicate of secondary glaucoma in the eye clinic. To further mimic the clinical setting, SO can be removed from the anterior chamber to reopen the drainage pathway and allow inflow of aqueous humor, which is drained through the trabecular meshwork (TM) at the angle of the anterior chamber. Because IOP quickly returns to normal, the model can be used to test the effect of lowering IOP on glaucomatous retinal ganglion cells. This method is straightforward, does not require special equipment or repeat procedures, closely simulates clinical situations, and may be applicable to diverse animal species. However, minor modifications may be required.

Here, we present a protocol to induce ocular hypertension and glaucomatous neurodegeneration in mouse eyes by intracameral injection of silicone oil and the procedure for silicone oil removal from the anterior chamber to return elevated intraocular pressure to normal.

Elevated intraocular pressure (IOP) is a well-documented risk factor for glaucoma. Here we describe a novel, effective method for consistently inducing ...