Name: the dimethylnitrosamine induced liver fibrosis model in the rat
Uploaded: 2016-06-17T14:15:00
Description: Watch this Scientific Journal Video about The Dimethylnitrosamine Induced Liver Fibrosis Model in the Rat at JoVE.com

The authors acknowledge the funding support from the Ministry of Education, Singapore, grant number MOE2010-IF-1-025.

All animal experiments were approved by the animal care and use committee of the School of Applied Science, Temasek Polytechnic.
1. Preparation of DMN
<ol>
	<li>Pipette 200 &#181;l of DMN (1 g/ml stock solution) and add 19.8 ml of PBS to prepare 10 mg/ml DMN solution for the injection. 
	Note: DMN is carcinogenic. Use a fume hood to prepare the DMN and perform the animal injections.</li>
</ol>
2. Intraperitoneal Injection of DMN
<ol>
	<li>Use male Wistar rats with an average weight...

<ol>
	<li>Magee, P. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Toxic+liver+injury;+the+metabolism+of+dimethylnitrosamine.">Toxic liver injury; the metabolism of dimethylnitrosamine.</a> Biochem J. 64 (4), 676-682 (1956).</li><li>Pritchard, D. J., Butler, W. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Apoptosis-the+mechanism+of+cell+death+in+dimethylnitrosamine-induced+hepatotoxicity.">Apoptosis-the mechanism of cell death in dimethylnitrosamine-induced hepatotoxicity.</a> J Pathol. 158 (3), 253-260 (1989).</li><li>Madden, J. W., Gertman, P. M., Peacock, E. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dimethylnitrosamine-induced+hepatic+cirrhosis:+a+new+canine+model+of+an+ancient+human+disease.">Dimethylnitrosamine-induced hepatic cirrhosis: a new canine model of an ancient human disease.</a> Surgery. 68 (1), 260-267 (1970).</li><li>Jenkins, S. A., Grandison, A., Baxter, J. N., Day, D. W., Taylor, I., Shields, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+dimethylnitrosamine-induced+model+of+cirrhosis+and+portal+hypertension+in+the+rat.">A dimethylnitrosamine-induced model of cirrhosis and portal hypertension in the rat.</a> J Hepatol. 1 (5), 489-499 (1985).</li><li>J&#233;z&#233;quel, A. M., Mancini, R., Rinaldesi, M. L., Macarri, G., Venturini, C., Orlandi, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+morphological+study+of+the+early+stages+of+hepatic+fibrosis+induced+by+low+doses+of+dimethylnitrosamine+in+the+rat.">A morphological study of the early stages of hepatic fibrosis induced by low doses of dimethylnitrosamine in the rat.</a> J Hepatol. 5 (2), 174-181 (1987).</li><li>George, J., Chandrakasan, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+characteristics+of+dimethylnitrosamine+induced+fibrotic+liver+collagen.">Molecular characteristics of dimethylnitrosamine induced fibrotic liver collagen.</a> Biochim Biophys Acta, Protein Struct Mol Enzymol. 1292 (2), 215-222 (1996).</li><li>Winwood, P. J., Arthur, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kupffer+cells:+their+activation+and+role+in+animal+models+of+liver+injury+and+human+liver+disease.">Kupffer cells: their activation and role in animal models of liver injury and human liver disease.</a> Semin Liver Dis. 13 (1), 50-59 (1993).</li><li>Nakamura, T., Sakata, R., Ueno, T., Sata, M., Ueno, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inhibition+of+transforming+growth+factor&#946;+prevents+progression+of+liver+fibrosis+and+enhances+hepatocyte+regeneration+in+dimethylnitrosamine-treated+rats.">Inhibition of transforming growth factor&#946; prevents progression of liver fibrosis and enhances hepatocyte regeneration in dimethylnitrosamine-treated rats.</a> Hepatology. 32 (2), 247-255 (2000).</li><li>Shek, F. W., Benyon, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=How+can+transforming+growth+factor+beta+be+targeted+usefully+to+combat+liver+fibrosis?.">How can transforming growth factor beta be targeted usefully to combat liver fibrosis?.</a> Eur J Gastroenterol Hepatol. 16 (2), 123-126 (2004).</li><li>Wang, J. H., Shin, J. W., Son, J. Y., Cho, J. H., Son, 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=Antifibrotic+effects+of+CGX,+a+traditional+herbal+formula,+and+its+mechanisms+in+rats.">Antifibrotic effects of CGX, a traditional herbal formula, and its mechanisms in rats.</a> J Ethnopharmacol. 127 (2), 534-542 (2010).</li><li>Su, L. J., Hsu, S. L., Yang, J. S., Tseng, H. H., Huang, S. F., Huang, C. Y. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Global+gene+expression+profiling+of+dimethylnitrosamine-induced+liver+fibrosis:+from+pathological+and+biochemical+data+to+microarray+analysis.">Global gene expression profiling of dimethylnitrosamine-induced liver fibrosis: from pathological and biochemical data to microarray analysis.</a> Gene Expr. 13 (2), 107-132 (2006).</li><li>M&#252;ller, A., Machnik, F., Zimmermann, T., Schubert, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thioacetamide-induced+cirrhosis-like+liver+lesions+in+rats+usefulness+and+reliability+of+this+animal+model.">Thioacetamide-induced cirrhosis-like liver lesions in rats usefulness and reliability of this animal model.</a> Exp Pathol. 34 (4), 229-236 (1988).</li><li>Martinez-Hernandez, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+hepatic+extracellular+matrix.+II.+Electron+immunohistochemical+studies+in+rats+with+CCl4-induced+cirrhosis.">The hepatic extracellular matrix. II. Electron immunohistochemical studies in rats with CCl4-induced cirrhosis.</a> Lab Invest. 53 (2), 166-186 (1985).</li><li>Pritchard, M. T., Apte, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Models+to+Study+Liver+Regeneration.">Models to Study Liver Regeneration.</a> Liver Regeneration. , 15-40 (2015).</li><li>Kountouras, J., Billing, B. H., Scheuer, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prolonged+bile+duct+obstruction:+a+new+experimental+model+for+cirrhosis+in+the+rat.">Prolonged bile duct obstruction: a new experimental model for cirrhosis in the rat.</a> Br J Exp Pathol. 65 (3), 305-311 (1984).</li><li>Marques, T. G., Chaib, E., 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=Review+of+experimental+models+for+inducing+hepatic+cirrhosis+by+bile+duct+ligation+and+carbon+tetrachloride+injection.">Review of experimental models for inducing hepatic cirrhosis by bile duct ligation and carbon tetrachloride injection.</a> Acta Cir Bras. 27 (8), 589-594 (2012).</li><li>Wasser, S., Tan, C. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+models+of+hepatic+fibrosis+in+the+rat.">Experimental models of hepatic fibrosis in the rat.</a> Ann Acad Med Singapore. 28 (1), 109-111 (1999).</li><li>George, J., Chandrakasan, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biochemical+abnormalities+during+the+progression+of+hepatic+fibrosis+induced+by+dimethylnitrosamine.">Biochemical abnormalities during the progression of hepatic fibrosis induced by dimethylnitrosamine.</a> Clin Biochem. 33 (7), 563-570 (2000).</li><li>Shimizu, I., Ma, Y. R., 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+Sho-saiko-to,+a+Japanese+herbal+medicine,+on+hepatic+fibrosis+in+rats.">Effects of Sho-saiko-to, a Japanese herbal medicine, on hepatic fibrosis in rats.</a> Hepatology. 29 (1), 149-160 (1999).</li><li>Wang, Y., Gao, J., Zhang, D., Zhang, J., Ma, J., Jiang, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+insights+into+the+antifibrotic+effects+of+sorafenib+on+hepatic+stellate+cells+and+liver+fibrosis.">New insights into the antifibrotic effects of sorafenib on hepatic stellate cells and liver fibrosis.</a> J Hepatol. 53 (1), 132-144 (2010).</li><li>Machholz, E., Mulder, G., Ruiz, C., Corning, B. F., Pritchett-Corning, K. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Manual+Restraint+and+Common+Compound+Administration+Routes+in+Mice+and+Rats.">Manual Restraint and Common Compound Administration Routes in Mice and Rats.</a> J Vis Exp. (67), (2012).</li><li>Lee, G., Goosens, K. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sampling+Blood+from+the+Lateral+Tail+Vein+of+the+Rat.">Sampling Blood from the Lateral Tail Vein of the Rat.</a> J Vis Exp. (99), (2015).</li><li>Parkinson, C. M., O'Brien, A., Albers, T. M., Simon, M. A., Clifford, C. B., Pritchett-Corning, K. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diagnostic+Necropsy+and+Selected+Tissue+and+Sample+Collection+in+Rats+and+Mice.">Diagnostic Necropsy and Selected Tissue and Sample Collection in Rats and Mice.</a> J Vis Exp. (54), (2011).</li><li>Ruehl-Fehlert, C., Kittel, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Revised+guides+for+organ+sampling+and+trimming+in+rats+and+mice--part+1.">Revised guides for organ sampling and trimming in rats and mice--part 1.</a> Exp Toxicol Pathol. 55 (2-3), 91-106 (2003).</li><li>Ishak, K., Baptista, 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=Histological+grading+and+staging+of+chronic+hepatitis.">Histological grading and staging of chronic hepatitis.</a> J Hepatol. 22 (6), 696-699 (1995).</li><li>Sant'Anna, L. B., Sant'Anna, N., Parolini, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Application+of+computer+assisted+image+analysis+for+identifying+and+quantifying+liver+fibrosis+in+a+experimental+model.">Application of computer assisted image analysis for identifying and quantifying liver fibrosis in a experimental model.</a> J Comput Interdiscip Sci. 2 (2), 139-148 (2011).</li></ol>

We have described a method to make an animal model of liver fibrosis and to assess the severity of liver fibrosis. It is important to deliver the correct dose of DMN and adhere to the schedule of weekly intraperitoneal injections. As the experiment progresses, it is crucial to weigh the rats and re-calculate the dose at the start of each week of DMN injections. Keep in mind that DMN is toxic and needs to be handled in the fume cabinet. We perform the intraperitoneal injections in the fume cabinet as well. With the need f...

DMN is a potent liver specific toxin. Its metabolism, tissue distribution, and ability to cause injury to livers of rats was reported by Magee1, and the mechanism of hepatocyte damage and cell death by apoptosis was described by Pritchard and Butler2. Intermittent administration of this compound was reported to induce liver fibrosis in dogs and rats3,4.
The mechanisms and morphologic changes of liver fibrosis have been extensively investigated using this model. In early studies using the rat, 3-week treatment with DMN produced centrilobular hemorrhagic necrosis followed by micronodular cirrhosis without steatosis5. It was shown that in early fibrosis, the collagen formed was more cross linked with type III being more prominent than type I6. In common with other causes, DMN-induced fibrotic changes were associated with an increase in Kupffer cells; hepatic macrophages that reside in the sinusoids. These cells morph into myofibroblasts and produce excessive amounts of extracellular matrix which is the primary problem in fibrosis7.
In terms of cellular signaling, Nakamura et al. demonstrated that TGF-&#946; plays a critical role in the progression of liver fibrosis8. They used an adenovirus expressing a truncated type II TGF-&#946; receptor, to specifically inhibit TGF-&#946; signaling. Liver fibrosis in these rats was spectacularly halted during DMN treatment when compared to control groups. Other studies have confirmed that suppression of TGF-&#946; leads to alleviation of liver fibrosis development9,10. The model was also used in a global gene profiling study to identify other fibrosis markers and proteins which could be used as drug targets for anti-fibrotic therapy11.
Other chemical agents used to induce liver fibrosis include thioacetamide (TAA) and carbon tetrachloride (CCl4). TAA was used first in rats and later in mice12. The advantages of this model include: ease of chemical administration in drinking water, the reproducibility of the model with characteristic micronodular cirrhosis and biochemical changes. The disadvantages include: the long time period of 3 months for liver fibrosis to develop and the lack of understanding of the molecular mechanism for induction of liver fibrosis. As for CCl4, its use has declined for the following reasons: it does not mimic human liver disease, has harmful effects on the ozone layer, causes pain and distress to animals, is very toxic to humans and requires extra precautions in its handling and disposal13,14.
Prolonged bile duct obstruction (by surgical intervention) as an experimental model for liver cirrhosis was first reported by Kountouras et al.15. This method is nontoxic to humans and animals. However, the time required for liver fibrosis to develop varies. A review of 30 reports by Marques et al.16, found that it took from seven days to four weeks after surgery for liver fibrosis to develop. The pathological changes described mimic those of human chronic biliary fibrosis and the model would be more suited for researchers interested in this area.
In summary, the intermittent administration of a constant dose of DMN in the rat over 4 weeks produces liver fibrosis that mimics the human disease. Dosed rats show progressive development of liver damage and parenchymal fibrosis4,17. Disease progression and severity can be monitored via blood samples or sacrifice of animals at specific time points and the effect is highly reproducible18. Thus the model has been widely used to study the mechanisms of liver fibrosis and cirrhosis as well as to screen for potential anti-fibrotic agents10,19,20.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Dimethylnitrosamine</td>
			<td>Wako</td>
			<td>147-03781</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Formalin</td>
			<td>Sinopharm chemicals</td>
			<td>F63257009</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Sigma</td>
			<td>64-17-5</td>
			<td></td>
		</tr>
		<tr>
			<td>Xylene</td>
			<td>Fisher</td>
			<td>1330-20-7</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Masson trichome stains</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Aniline Blue</td>
			<td>Electron Microscopy Sciences</td>
			<td>#42755</td>
			<td></td>
		</tr>
		<tr>
			<td>Acid Fuschin</td>
			<td>Electron Microscopy Sciences</td>
			<td>RT42685</td>
			<td></td>
		</tr>
		<tr>
			<td>Scarlet Red</td>
			<td>Electron Microscopy Sciences</td>
			<td>#26905</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphotungstic Acid Hydrate</td>
			<td>ALFA AESAR</td>
			<td>ALFA40116.4</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphomolybdic Acid Hydrate</td>
			<td>Sigma SG</td>
			<td>221856-25G</td>
			<td></td>
		</tr>
		<tr>
			<td>Weigert&#39;s Iron Hematoxilyn</td>
			<td>Merck</td>
			<td>1.15973.0002</td>
			<td></td>
		</tr>
		<tr>
			<td>DPX Mounting Medium</td>
			<td>Merck</td>
			<td>HX066873</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue processor</td>
			<td>Leica</td>
			<td>Leica TP 1020</td>
			<td></td>
		</tr>
		<tr>
			<td>Embedding machine</td>
			<td>Sakura</td>
			<td>&#160;Sakura Tissue Tek TEC5 Embedding System</td>
			<td></td>
		</tr>
		<tr>
			<td>Microtome</td>
			<td>Leica</td>
			<td>Leica RM 2235</td>
			<td></td>
		</tr>
		<tr>
			<td>Vet Test Analyzer</td>
			<td>Idexx</td>
			<td>Vet Test 8008</td>
			<td></td>
		</tr>
	</tbody>
</table>

the dimethylnitrosamine induced liver fibrosis model in the rat

Four to six week old, male Wistar rats were used to produce animal models of liver fibrosis. The process requires four weeks of administration of 10 mg/kg dimethylnitrosamine (DMN), given intraperitoneally for three consecutive days per week. Intraperitoneal injections were performed in the fume hood as DMN is a known hepatoxin and carcinogen. The model has several advantages. Firstly, liver changes can be studied sequentially or at particular stages of interest. Secondly, the stage of liver disease can be monitored by measurement of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) enzymes. Thirdly, the severity of liver damage at different stages can be confirmed by sacrifice of animals at designated time points, followed by histological examination of Masson&#39;s Trichome stained liver tissues. After four weeks of DMN dosing, the typical fibrosis score is 5 to 6 on the Ishak scale. The model can be reproduced consistently and has been widely used to assess the efficacy of potential anti-fibrotic agents.

DMN treated rats lose weight and become less vigorous with ruffled hair coat. There is significant loss in average body weights of DMN treated rats; first detectable after 2 weeks of DMN treatment, and this difference remains through weeks 3 and 4 after DMN treatment (Figure 1a). As the rats receive DMN over successive weeks, damage to the liver causes it to become smaller. The liver index; which is the percent of liver weight at final body weight was significantly lower ...

Watch this Scientific Journal Video about The Dimethylnitrosamine Induced Liver Fibrosis Model in the Rat at JoVE.com

The Dimethylnitrosamine Induced Liver Fibrosis Model in the Rat

We describe a method to produce an animal model of liver fibrosis in the rat, and assess the degree of fibrosis by histological examination of the liver. The model can be used to study the development of liver disease as well as to test the efficacy of potential anti-fibrotic agents.

Four to six week old, male Wistar rats were used to produce animal models of liver fibrosis. The process requires four weeks of administration of 10 mg/kg ...

The overall goal of this procedure is to produce an animal model of liver fibrosis that can be used to assess the efficacy of potential anti-fibrotic agents. This animal model can help answer key questions about the nature and development of fibrosis in the liver and how anti-fibrotic agents reduce the fibrotic process. Furthermore, this model mimics the complex physiological processes of human liver disease from early to late-stage fibrosis and can be studied at any point of interest of the disease.Individuals new to this method need to plan the workflow because the den-glis-nov animal model takes at least five weeks. After the liver has been harvested, the processing requires one or two weeks before especially stained sections are ready to be examined by the pathologist. DMN must be diluted from a stock to 10 milligrams per milliliter in PBS.When performing this dilution, be sure to work in a fume hood as the substance is a carcinogen. For the experiment, select male Wistar rats between 150 and 200 grams. Acclimate the rats to a housing facility with a normal climate for at least four days.Provide food and water ad libitum and measure their daily intake. On a weekly basis, measure the rat's body weight and take a blood sample. For the DMN treatment, at the fume hood, prepare and inject 10 milligrams per kilogram doses.Use a 25 gauge needle and intraperitoneally inject the lower-right quadrant of the abdomen. Inject the rats for three consecutive days and repeat this process weekly for four weeks. Always on the same three days, and importantly, adjust the DMN dose weekly over the four-week period.Euthanize the DMN-treated animals four to five days after their last injection. On a dissecting board, disinfect and moisten the abdominal skin with 70%ethanol. Then, using scissors, incise the skin from the anus to the chin and reflect it apart.Next, incise the abdominal wall from the anus to the zyphoid cartilage to expose the abdominal viscera. Check the organs for abnormalities such as inappropriate color, size, location, or fluids within the peritaneal cavity. Also probe the organs for their consistency and note any abnormal odors.Next, isolate the liver. Begin at the hilus, the diaphragm attachment point, and work around the liver from there, freeing it from surrounding ligaments and vessels. Then, transfer the liver to a dish and record its weight.Now, using a scalpel, from one lobe, make a five millimeter block that extends one to two centimeters into the lobe for sectioning. Then, make one or two more blocks, preferably from the same lobe, to serve as back-ups. The remaining liver can be stored frozen.Fix the tissue blocks in 10%forumlulin with at least ten times more fixative than tissue. After 24 or more hours of fixation, trim the liver samples and place them into cassettes. Then load the basket for the automated tissue processor.Fully submerge the basket into the first processing station filled with 10%buffered formulin. Then, continue with one-hour baths in an ethanol series followed by xylene, followed by paraffin. Next, warm up the embedding station for at least an hour.Once warm, transfer liver samples into the wax bath. After two to three minutes, use warmed forceps to transfer the cassette to a 65 degree Celsius hotplate. Then half-fill the mold with warm, liquid paraffin.Next, transfer the tissue out of the cassette and into the paraffin with the cut surface flat on the mold. Then, finish filling the mold with warmed paraffin. Mount the empty cassette on top of the paraffin to serve as a label and support.Then, place the mold on a four-deegree Celsius block to cool for 30 minutes. Once cooled, pop out the paraffin block. If the block cracks, melt it and repeat the embedding.Now, section the block on a microtome. Make ten micron thick sections until the tissue is visible. And then make five micron thick sections.Next, carefully transfer the sections to a 40-degree Celsius water bath, holding them at their edges. Let the sections float and lift them off the water onto clean glass slides. Now, place all the slides on a slide warmer at 37 degree Celsius and let them dry overnight.To begin, remove the paraffin and re-hydrate the tissues with xylene and decreasing concentrations of ethanol. Then, immerse the slides in iron hematoxylin for 10 minutes to stain the nuclei. After 10 minutes, briefly rinse the slides with water.Then, immerse the slides in Biebrich scarlet acid fuchsin for two minutes to stain the cytoplasm. Follow with a water rinse as before. Next, immerse the slides in freshly-made PTA for 10 minutes to promote the uptake of aniline blue.Logically, next, immerse the slides in aniline blue for 10 minutes to stain the collagen fibers. Now, rinse off the excess stain with water and transfer the slides to a 1%acetic acid bath for one minute. To render the color of the slide more delicate and transparent.Over four weeks of DMN treatment, male Wister rats lost weight and became less vigorous. Weight loss was first detectable after two weeks. Gradually, damage to the liver weakened the rats.The liver to body weight ratio was significantly lower in the DMN-treated animals. Grossly, the treated livers were smaller and harder when compared to controls. As expected, serum indicators of a hepatocyte damage, ALT and AST, were at elevated levels in the treated group.Histological examination was made using a standardized set of criteria. The DMN treatment led to progressive increase and expansion of fibrous septa with loss of hepatocytes. Collagen deposits are stained blue.There was fibrous expansion of portal areas with portal-to-portal bridging and portal-to-central bridging. By four weeks of treatment, there was cirrhosis with nodule formation. With the need for repeated injections, the correct dressing and technique of injections is important to a wide interaction of contamination and damage to internal organs.Don't forget that DMN is toxic, and all the injections should be done in the fume hood. Cutting good, five micromedial, thin sections on the microtome requires practice and patience, during the staining process. Ensure that the sections are kept moist at all times and transfer it from one staining solution to the next according to the specified timing.In summary, rats produced in this model, show progressive liver disease and pericardial fibrosis which can be monitored by biochemical states. We have studied various aspects of liver disease progression and tested potential anti-fibrotic agents using this model.

the-dimethylnitrosamine-induced-liver-fibrosis-model-in-the-rat

Research

JoVE Journal

Medicine

Method of Direct Segmental Intra-hepatic Delivery Using a Rat Liver Hilar Clamp Model

Major hepatic surgery with inflow occlusion, and liver transplantation, necessitate a period of warm ischemia, and a period of reperfusion leading to ischemia/reperfusion (I/R) injury with myriad negative consequences. Potential I/R injury in marginal organs destined for liver transplantation contributes to the current donor shortage secondary to a decreased organ utilization rate. A significant need exists to explore hepatic I/R injury in order to mediate its impact on graft function in transplantation. Rat liver hilar clamp models are used to investigate the impact of different molecules on hepatic I/R injury. Depending on the model, these molecules have been delivered using inhalation, epidural infusion, intraperitoneal injection, intravenous administration or injection into the peripheral superior mesenteric vein. A rat liver hilar clamp model has been developed for use in studying the impact of pharmacologic molecules in ameliorating I/R injury. The described model for rat liver hilar clamp includes direct cannulation of the portal supply to the ischemic hepatic segment via a side branch of the portal vein, allowing for direct segmental hepatic delivery. Our approach is to induce ischemia in the left lateral and median lobes for 60 min, during which time the substance under study is infused. In this case, pegylated-superoxide dismutase (PEG-SOD), a free radical scavenger, is infused directly into the ischemic segment. This series of experiments demonstrates that infusion of PEG-SOD is protective against hepatic I/R injury. Advantages of this approach include direct injection of the molecule into the ischemic segment with consequent decrease in volume of distribution and reduction in systemic side effects.

A unique rat liver hilar clamp model was developed for studying the impact of pharmacologic molecules in ameliorating ischemia-reperfusion injury. This model includes direct cannulation of the portal supply to the ischemic liver segment via a branch of the portal vein, allowing for direct hepatic delivery.

Major hepatic surgery with inflow occlusion, and liver transplantation, necessitate a period of warm ischemia, and a period of reperfusion leading to ...

Rat Model of the Associating Liver Partition and Portal Vein Ligation for Staged Hepatectomy (ALPPS) Procedure

Recent clinical data support an aggressive surgical approach to both primary and metastatic liver tumors. For some indications, like colorectal liver metastases, the amount of liver tissue left behind after liver resection has become the main limiting factor of resectability of large or multiple liver tumors. A minimal amount of functional tissue is required to avoid the severe complication of post-hepatectomy liver failure, which has high morbidity and mortality. Inducing liver growth of the prospective remnant prior to resection has become more established in liver surgery, either in the form of portal vein embolization by interventional radiologists or in the form of portal vein ligation several weeks prior to resection. Recently, it was shown that liver regeneration is more extensive and rapid, when the parenchymal transection is added to portal vein ligation in a first stage and then, after only one week of waiting, resection performed in a second stage (Associating Liver Partition and Portal vein ligation for Staged hepatectomy = ALPPS). ALPPS has rapidly become popular across the world, but has been criticized for its high perioperative mortality. The mechanism of accelerated and extensive growth induced by this procedure has not been well understood. Animal models have been developed to explore both the physiological and molecular mechanisms of accelerated liver regeneration in ALPPS. This protocol presents a rat model that allows mechanistic exploration of accelerated regeneration.

Rat Model of the Associating Liver Partition and Portal Vein Ligation for Staged Hepatectomy ALPPS Procedure

Inducing rapid liver hypertrophy using Associating Liver Partition and Portal vein ligation for a Staged hepatectomy (ALPPS) has been proposed for resection of borderline resectable liver tumors. This model may elucidate mechanisms involved in rapid hypertrophy and allows testing of drugs that promote or block the acceleration of regeneration.

Recent clinical data support an aggressive surgical approach to both primary and metastatic liver tumors. For some indications, like colorectal liver ...

Re-Arterialized Rat Partial Liver Transplantation with an in vivo Vessel-Oriented 70% Hepatectomy

Split liver transplantation and living liver donor liver transplantation were developed in the clinic to utilize liver organs in a more efficient manner. To better understand the mechanism behind these surgical procedures, a rat partial liver transplantation (PLTx) model was established for relevant surgical studies. Because of the complexity of the rat PLTx model, a protocol with detailed descriptions is required. An article published previously reported a protocol in which ex vivo hepatectomy was used to achieve 50% rat PLTx. In contrast to this protocol, we introduced a re-arterialized PLTx with an in vivo 70% hepatectomy. An updated vessel-oriented hepatectomy was incorporated into the rat PLTx to refine the microsurgical procedure. The portal veins and hepatic arteries of the left lateral lobe and the median lobe were individually dissected and ligated before removal of the liver parenchyma, thereby decreasing the probability of bleeding in the remnant liver stump. Furthermore, an end-to-side vessel anastomosis between the common hepatic artery and the enlarged proper hepatic artery was introduced to re-arterialize the hepatic artery. By using this end-to-side vessel anastomosis technique, the diameter of the anastomosis was enlarged, thereby decreasing the difficulty of hand suture and maintaining a high rate of anastomotic patency. Moreover, the cuff anastomosis of the infrahepatic vena cava was slightly modified. A section of circumferential liver parenchyma around the vena cava of a recipient was preserved during cuff anastomosis to maintain the three-dimensional shape of the vascular lumen. This section of liver parenchyma was removed after completing the anastomosis. With this modification, the step involving placement of stay sutures was omitted, thereby further shortening the cuff anastomosis time. By using this protocol of rat PLTx, a low liver enzyme level, an intact liver lobular architecture and a high survival rate were achieved after microsurgery.

Re-Arterialized Rat Partial Liver Transplantation with an in vivo Vessel-Oriented 70% Hepatectomy

Here, a protocol involving re-arterialized rat partial liver transplantation is presented. Specifically, 70% liver was resected in vivo by using an updated technique of vessel-oriented hepatectomy. The hepatic artery was reconstructed in an end-to-side manner. The cuff technique was modified to shorten the anastomosis time of the infrahepatic vena cava.

Split liver transplantation and living liver donor liver transplantation were developed in the clinic to utilize liver organs in a more efficient manner. ...

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 ...

Left Atrial Stenosis Induced Pulmonary Venous Arterialization and Group 2 Pulmonary Hypertension in Rat

The mechanism of mitral stenosis-induced pulmonary venous arterialization and group 2 pulmonary hypertension (PH) is unclear. There is no rodent model of group 2 PH, due to mitral stenosis (MS), to facilitate the investigation of disease mechanisms and potential therapeutic strategies. We present a novel rat model of pulmonary venous congestion-induced pulmonary venous arterialization and group 2 PH caused by left atrial stenosis (LAS). LAS is achieved by constricting the left atrium using a half-closed titanium clip. After the LAS surgery, a rat model with a transmitral inflow velocity greater than or equal to 2.0 m/s on echocardiography gradually develops pulmonary venous arterialization and group 2 PH over an 8- to 10-week period. In this protocol, we provide the step-by-step procedure of how to perform the LAS surgery. The presented LAS rat model mimics MS in humans and is useful for studying the underlying molecular mechanism of pulmonary venous arterialization and for the preclinical evaluation of therapies for group 2 PH.

Left atrial stenosis (LAS) is a novel surgical technique used for studying group 2 pulmonary hypertension (PH) and mechanisms underlying pulmonary venous arterialization. Here, we present a protocol to constrict the left atrium using a titanium clip to cause pulmonary venous arterialization and moderate PH in a rat.

The mechanism of mitral stenosis-induced pulmonary venous arterialization and group 2 pulmonary hypertension (PH) is unclear. There is no rodent model of ...

Murine Precision-Cut Liver Slices as an Ex Vivo Model of Liver Biology

Understanding the mechanisms of liver injury, hepatic fibrosis, and cirrhosis that underlie chronic liver diseases (i.e., viral hepatitis, non-alcoholic fatty liver disease, metabolic liver disease, and liver cancer) requires experimental manipulation of animal models and in vitro cell cultures. Both techniques have limitations, such as the requirement of large numbers of animals for in vivo manipulation. However, in vitro cell cultures do not reproduce the structure and function of the multicellular hepatic environment. The use of precision-cut liver slices is a technique in which uniform slices of viable mouse liver are maintained in laboratory tissue culture for experimental manipulation. This technique occupies an experimental niche that exists between animal studies and in vitro cell culture methods. The presented protocol describes a straightforward and reliable method to isolate and culture precision-cut liver slices from mice. As an application of this technique, ex vivo liver slices are treated with bile acids to simulate cholestatic liver injury and ultimately assess the mechanisms of hepatic fibrogenesis.

This protocol provides a simple and reliable method for the production of viable precision-cut liver slices from mice. The ex vivo tissue samples can be maintained under laboratory tissue culture conditions for multiple days, providing a flexible model to examine liver pathobiology.

Understanding the mechanisms of liver injury, hepatic fibrosis, and cirrhosis that underlie chronic liver diseases (i.e., viral hepatitis, non-alcoholic ...

Organ Ischemia-Reperfusion Injury by Simulating Hemodynamic Changes in Rat Liver Transplant Model

Orthotopic liver transplantation (OLT) in rats is a tried and proven animal model used for preoperative, intraoperative, and postoperative studies, including ischemia-reperfusion injury (IRI) of extrahepatic organs. This model requires numerous experiments and devices. The duration of anhepatic phase is closely related to the time to develop IRI after transplantation. In this experiment, we used hemodynamic changes to induce extrahepatic organ damage in rats and determined the maximum tolerance time. The time until the most severe organ injury varied for different organs. This method can easily be replicated and can also be used to study IRI of the extrahepatic organs after liver transplantation.

This paper provides a detailed description of how to build an animal model of the anhepatic phase (liver ischemia) in rats to facilitate basic research into ischemia-reperfusion injury after liver transplantation.

Orthotopic liver transplantation (OLT) in rats is a tried and proven animal model used for preoperative, intraoperative, and postoperative studies, ...

A Rat Lung Transplantation Model of Warm Ischemia/Reperfusion Injury: Optimizations to Improve Outcomes

From our experience with rat lung transplantation, we have found several areas for improvement. Information in the existing literature regarding methods for choosing appropriate cuff sizes for the pulmonary vein (PV), pulmonary artery (PA), or bronchus (Br) are varied, thus making the determination of proper cuff size during rat lung transplantation an exercise of trial and error. By standardizing the cuffing technique to use the smallest effective cuff appropriate for the size of the vessel or bronchus, one can make the transplantation procedure safer, faster, and more successful. Since diameters of the PV, PA, and Br are related to the body weight of the rat, we present a strategy to choosing an appropriate size using a weight-based guide. Since lung volume is also related to body weight, we recommend that this relationship should also be considered when choosing the proper volume of air for donor lung inflation during warm ischemia as well as for the proper volume of PBS to be instilled during bronchoalveolar lavage (BAL) fluid collection. We also describe methods for 4th intercostal space dissection, wound closure, and sample collection from both the native and transplanted lobes.

Here, we present optimizations to a rat lung transplantation model that serve to improve outcomes. We provide a size guide for cuffs based on body weight, a measurement strategy to ascertain the 4th intercostal space, and methods of wound closure and BAL (bronchoalveolar lavage) fluid and tissue collection.

From our experience with rat lung transplantation, we have found several areas for improvement. Information in the existing literature regarding methods ...

Establishing a Silicosis Rat Model via Exposure of Whole-Body to Respirable Silica

The major cause of silicosis is the inhalation of silica in the occupational environment. Despite some anatomical and physiological differences, rodent models continue to be an essential tool for studying human silicosis. For silicosis, the classic pathological process needs to be inducible via the inhalation of freshly generated quartz particles, which means specifically inducing human occupational disease. This study described a technique to establish and effectively mimic the pathological dynamic evolution process of silicosis. Further, the technique had good repeatability with no surgery involved. The inhalation exposure system was fabricated, validated, and used for toxicology studies on respirable particle inhalation. The critical components were as follows: (1) bulk dry SiO2 powder generator adjusted with an air-flow controller; (2) 0.3 m3 whole-body inhalation exposure chamber accommodating up to 3&#160;adult rats; (3) a monitoring and control system for regulating oxygen concentration, temperature, humidity, and pressure in real-time; and (4) a barrier and waste disposal system for protecting laboratory technicians and the environment. In summary, the present protocol reports the inhalation via the whole body, and the inhalation chamber created a reliable, reasonable, and repeatable rat silicotic model with low mortality, less injury, and more protection.

This study describes a technique to establish a silicosis rat model with the inhalation of silica through the whole body in an inhalation chamber. The rats with silicosis could closely mimic the pathological process of human silicosis in an easy, cost-effective manner with good repeatability.

The major cause of silicosis is the inhalation of silica in the occupational environment. Despite some anatomical and physiological differences, rodent ...

Quantitative Analysis of Liver Stiffness Distribution

A Three-Dimensional Digital Model for Early Diagnosis of Hepatic Fibrosis Based on Magnetic Resonance Elastography

Hepatic fibrosis is an early stage of liver cirrhosis, and there are no better non-invasive and convenient methods for the detection and evaluation of the disease. Despite the good progress made with the liver stiffness map (LSM) based on magnetic resonance elastography (MRE), there are still some limitations that need to be overcome, including manual focus determination, manual selection of regions of interest (ROIs), and discontinuous LSM data without structural information, which makes it impossible to evaluate the liver as a whole. In this study, we propose a novel three-dimensional (3D) digital model for the early diagnosis of hepatic fibrosis based on MRE.
MRE is a non-invasive imaging technique that employs magnetic resonance imaging (MRI) to measure the liver stiffness at the scanning site through human-computer interaction. Studies have indicated a significant positive correlation between the LSM obtained through MRE and the degree of hepatic fibrosis. However, for clinical purposes, a comprehensive and precise quantification of the degree of hepatic fibrosis is necessary. To address this, the concept of Liver Stiffness Distribution (LSD) was proposed in this study, which refers to the 3D stiffness volume of each liver voxel obtained by the alignment of 3D liver tissue images and MRE indicators. This provides a more effective clinical tool for the diagnosis and treatment of hepatic fibrosis.

Author Spotlight: Advancing Hepatic Fibrosis Diagnosis Using Magnetic Resonance Elastography and AI 

The objective of this study was to develop a novel three-dimensional digital model for the early diagnosis of hepatic fibrosis, which includes the stiffness of each voxel in the patient's liver and can thus, be used to calculate the distribution ratio of the patient's liver at different fibrosis stages.

Hepatic fibrosis is an early stage of liver cirrhosis, and there are no better non-invasive and convenient methods for the detection and evaluation of the ...