This work was supported by grants from the National Health and Medical Research Council (NHMRC) of Australia (APP1042370, APP1061332, APP1087125). The authors would like to thank the Curtin Health Innovation Research Institute staff for technical assistance.

1. Animal Experimentation
All animal studies described in this investigation were approved by the Curtin University Animal Ethics Committee (Approval number: AEC_2014_28) prior to commencement of the experiments and performed in accordance with the Australian code for the care and use of animals.
<ol>
	<li>Animals
	<ol>
		<li>Use six-week old male C57BL/6J mice for the experiments.</li>
	</ol>
	</li>
	<li>Experimental design
	<ol>
		<li>Following arrival at the Animal Facility, allow mice to acclimatize for four days prior to commencement of any experiments.</li>
		<li>House mice on wheaten chaff bedding, which has been depleted of visible grains and stalks and keep mice on 12-hour day/night cycles in individually ventilated cages. Change bedding on days three and seven, then weekly thereafter.</li>
		<li>Provide mice with ad libitum access to the choline-deficient diet and drinking water supplemented with 0.15% of DL-ethionine. Keep the DL-ethionine-supplemented water at 4&#176;C and replace drinking water every second day to ensure freshness and encourage drinking. Top up the choline-deficient chow every second day with a complete change of chow once a week.</li>
		<li>Observe mice at rest and during handling. Monitor standard signs of animal health, including overall appearance, posture, social interaction, grooming, coat condition, and body weight.</li>
		<li>Weigh mice daily during the first two weeks of the experiment to ensure any animals exhibiting more than 20% body weight loss are euthanized to limit undue suffering. This is typically the case in less than 5% of animals. After two weeks, the frequency of weighing can be reduced to three times weekly (e.g., Monday, Wednesday, Friday).</li>
	</ol>
	</li>
	<li>Liver perfusion and isolation
	<ol>
		<li>Anesthetize mice at indicated time points (in this study one, two, and six weeks on the CDE diet) with ketamine (100 mg/kg) and xylazine (10 mg/kg) by intraperitoneal injection. Test the pedal withdrawal reflex to ensure adequate anesthesia.</li>
		<li>Wet the fur with 70% ethanol and make a vertical midline incision in the abdominal wall up to the diaphragm using Mayo scissors. The rib cage can be removed for easier access to the heart.</li>
		<li>Collect blood by slow cardiac puncture using a 25 G x 1/2&#34; regular wall needle to avoid collapsing of the heart. Allow the blood to clot in a microcentrifuge tube at room temperature to obtain serum samples after centrifugation at 2,000 x g for 10 min. Later, measure serum alanine transaminase levels by standard procedures12.</li>
		<li>Move the stomach and small intestine to the side and expose the portal vein. Cut the heart using Mayo scissors to allow fluids to exit and perfuse the liver with sterile phosphate buffered saline (pH=7.4) by cannulating the portal vein using a 27 G x 1/2&#34; regular wall needle. An evenly blanched liver indicates successful perfusion of all liver lobes.</li>
		<li>Carefully detach the liver and place it in a petri dish using forceps and Mayo scissors. Remove excess, non-liver tissue and the gallbladder.</li>
	</ol>
	</li>
	<li>Liver preservation
	<ol>
		<li>After the total liver weight has been recorded, cut one small lobe into several small pieces of a few square millimeters, transfer them to sterile tubes, and snap-freeze in liquid nitrogen for later RNA and protein extraction, as per standard protocols. Snap-freeze these tissue pieces as soon as possible after organ collection to avoid any tissue degradation.</li>
		<li>Collect one lobe in 10% neutral buffered formalin for later processing and paraffin embedding, as per standard protocols.</li>
		<li>Place one lobe into a mold filled with optimum cutting temperature cryomatrix embedding resin&#160;and snap-freeze in liquid nitrogen.</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Taub, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Liver+regeneration:+from+myth+to+mechanism.">Liver regeneration: from myth to mechanism.</a> Nat Rev Mol Cell Biol. 5, 836-847 (2004).</li><li>Kohn-Gaone, J., Gogoi-Tiwari, J., Ramm, G. A., Olynyk, J. K., Tirnitz-Parker, 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=The+role+of+liver+progenitor+cells+during+liver+regeneration,+fibrogenesis,+and+carcinogenesis.">The role of liver progenitor cells during liver regeneration, fibrogenesis, and carcinogenesis.</a> Am J Physiol Gastrointest Liver Physiol. 310, G143-G154 (2016).</li><li>Lu, W. 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=Hepatic+progenitor+cells+of+biliary+origin+with+liver+repopulation+capacity.">Hepatic progenitor cells of biliary origin with liver repopulation capacity.</a> Nat Cell Biol. 17, 971-983 (2015).</li><li>Prakoso, 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=Analysis+of+the+intrahepatic+ductular+reaction+and+progenitor+cell+responses+in+hepatitis+C+virus+recurrence+after+liver+transplantation.">Analysis of the intrahepatic ductular reaction and progenitor cell responses in hepatitis C virus recurrence after liver transplantation.</a> Liver Transpl. 20, 1508-1519 (2014).</li><li>Tirnitz-Parker, J. E., Tonkin, J. N., Knight, B., Olynyk, J. K., Yeoh, G. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation,+culture+and+immortalisation+of+hepatic+oval+cells+from+adult+mice+fed+a+choline-deficient,+ethionine-supplemented+diet.">Isolation, culture and immortalisation of hepatic oval cells from adult mice fed a choline-deficient, ethionine-supplemented diet.</a> Int J Biochem Cell Biol. 39, 2226-2239 (2007).</li><li>Van Hul, N. K., Abarca-Quinones, J., Sempoux, C., Horsmans, Y., Leclercq, I. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Relation+between+liver+progenitor+cell+expansion+and+extracellular+matrix+deposition+in+a+CDE-induced+murine+model+of+chronic+liver+injury.">Relation between liver progenitor cell expansion and extracellular matrix deposition in a CDE-induced murine model of chronic liver injury.</a> Hepatology. 49, 1625-1635 (2009).</li><li>Clouston, A. D., 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=Fibrosis+correlates+with+a+ductular+reaction+in+hepatitis+C:+roles+of+impaired+replication,+progenitor+cells+and+steatosis.">Fibrosis correlates with a ductular reaction in hepatitis C: roles of impaired replication, progenitor cells and steatosis.</a> Hepatology. 41, 809-818 (2005).</li><li>Forbes, S. J., Newsome, 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=Liver+regeneration+-+mechanisms+and+models+to+clinical+application.">Liver regeneration - mechanisms and models to clinical application.</a> Nat Rev Gastroenterol Hepatol. 13, 473-485 (2016).</li><li>Akhurst, 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=A+modified+choline-deficient,+ethionine-supplemented+diet+protocol+effectively+induces+oval+cells+in+mouse+liver.">A modified choline-deficient, ethionine-supplemented diet protocol effectively induces oval cells in mouse liver.</a> Hepatology. 34, 519-522 (2001).</li><li>Shinozuka, H., Lombardi, B., Sell, S., Iammarino, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Early+histological+and+functional+alterations+of+ethionine+liver+carcinogenesis+in+rats+fed+a+choline-deficient+diet.">Early histological and functional alterations of ethionine liver carcinogenesis in rats fed a choline-deficient diet.</a> Cancer Res. 38, 1092-1098 (1978).</li><li>Knight, B., Tirnitz-Parker, J. E., Olynyk, J. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=C-kit+inhibition+by+imatinib+mesylate+attenuates+progenitor+cell+expansion+and+inhibits+liver+tumor+formation+in+mice.">C-kit inhibition by imatinib mesylate attenuates progenitor cell expansion and inhibits liver tumor formation in mice.</a> Gastroenterology. 135, 969-979 (2008).</li><li>Kohn-Gaone, 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=Divergent+Inflammatory,+Fibrogenic,+and+Liver+Progenitor+Cell+Dynamics+in+Two+Common+Mouse+Models+of+Chronic+Liver+Injury.">Divergent Inflammatory, Fibrogenic, and Liver Progenitor Cell Dynamics in Two Common Mouse Models of Chronic Liver Injury.</a> Am J Pathol. 186, 1762-1774 (2016).</li><li>Knight, 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=Attenuated+liver+progenitor+(oval)+cell+and+fibrogenic+responses+to+the+choline+deficient,+ethionine+supplemented+diet+in+the+BALB/c+inbred+strain+of+mice.">Attenuated liver progenitor (oval) cell and fibrogenic responses to the choline deficient, ethionine supplemented diet in the BALB/c inbred strain of mice.</a> J Hepatol. 46, 134-141 (2007).</li><li>Dwyer, B. J., Olynyk, J. K., Ramm, G. A., Tirnitz-Parker, 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=TWEAK+and+LTbeta+Signaling+during+Chronic+Liver+Disease.">TWEAK and LTbeta Signaling during Chronic Liver Disease.</a> Front Immunol. 5, 39 (2014).</li><li>Karin, M., Clevers, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reparative+inflammation+takes+charge+of+tissue+regeneration.">Reparative inflammation takes charge of tissue regeneration.</a> Nature. 529, 307-315 (2016).</li><li>Ruddell, R. G., 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=Lymphotoxin-beta+receptor+signaling+regulates+hepatic+stellate+cell+function+and+wound+healing+in+a+murine+model+of+chronic+liver+injury.">Lymphotoxin-beta receptor signaling regulates hepatic stellate cell function and wound healing in a murine model of chronic liver injury.</a> Hepatology. 49, 227-239 (2009).</li><li>Tirnitz-Parker, J. 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=Tumor+necrosis+factor-like+weak+inducer+of+apoptosis+is+a+mitogen+for+liver+progenitor+cells.">Tumor necrosis factor-like weak inducer of apoptosis is a mitogen for liver progenitor cells.</a> Hepatology. 52, 291-302 (2010).</li><li>Viebahn, C. S., Yeoh, G. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=What+fires+prometheus?+The+link+between+inflammation+and+regeneration+following+chronic+liver+injury.">What fires prometheus? The link between inflammation and regeneration following chronic liver injury.</a> Int J Biochem Cell Biol. 40, 855-873 (2008).</li><li>Hayner, N. T., Braun, L., Yaswen, P., Brooks, M., Fausto, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isozyme+profiles+of+oval+cells,+parenchymal+cells,+and+biliary+cells+isolated+by+centrifugal+elutriation+from+normal+and+preneoplastic+livers.">Isozyme profiles of oval cells, parenchymal cells, and biliary cells isolated by centrifugal elutriation from normal and preneoplastic livers.</a> Cancer Res. 44, 332-338 (1984).</li><li>Tee, L. B., Smith, P. G., Yeoh, G. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Expression+of+alpha,+mu+and+pi+class+glutathione+S-transferases+in+oval+and+ductal+cells+in+liver+of+rats+placed+on+a+choline-deficient,+ethionine-supplemented+diet.">Expression of alpha, mu and pi class glutathione S-transferases in oval and ductal cells in liver of rats placed on a choline-deficient, ethionine-supplemented diet.</a> Carcinogenesis. 13, 1879-1885 (1992).</li><li>Chayanupatkul, 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=Hepatocellular+carcinoma+in+the+absence+of+cirrhosis+in+patients+with+chronic+hepatitis+B+virus+infection.">Hepatocellular carcinoma in the absence of cirrhosis in patients with chronic hepatitis B virus infection.</a> J Hepatol. 66, 355-362 (2017).</li><li>Mittal, S., 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=Hepatocellular+Carcinoma+in+the+Absence+of+Cirrhosis+in+United+States+Veterans+is+Associated+With+Nonalcoholic+Fatty+Liver+Disease.">Hepatocellular Carcinoma in the Absence of Cirrhosis in United States Veterans is Associated With Nonalcoholic Fatty Liver Disease.</a> Clin Gastroenterol Hepatol. 14, 124-131 (2016).</li></ol>

There is nothing to be disclosed by the authors.

Chronic liver disease is often a silent disease with most patients being asymptomatic and it is one of the major contributors to morbidity and mortality worldwide. Chronic alcoholism and hepatitis C virus infection are the leading causes. Chronic liver injury is characterized by hepatic inflammation, fibrosis and in severe cases cirrhosis, carcinoma and ultimately liver failure. There is currently no cure available and although major advances have been made to understand the mechanisms of liver disease, new therapeutic a...

The liver is the largest glandular metabolic organ of the body and has many complex functions. Key roles for the liver include digestion, metabolism, detoxification, storage of essential nutrients, production of blood plasma protein components, and immunity mediated through resident macrophages or Kupffer cells. The liver has a great ability to regenerate even if up to 70-90% of its total mass is lost. In the event of acute liver injury, such as seen following a partial hepatectomy or acetaminophen poisoning, the remaining healthy hepatocytes proliferate to repair the damage in a highly coordinated process1. However, when the hepatocytes are chronically injured due to long-term viral infection, alcoholic or non-alcoholic fatty liver disease, the inflammatory microenvironment triggers the activation of fibrosis-driving hepatic stellate cells and the proliferation of liver progenitor cells (LPCs) with the potential to differentiate into either cholangiocytes or hepatocytes2,3,4,5. The precise origin, differentiation fate of LPCs, their contribution to liver regeneration, and hepatocarcinogenesis have been topics of intense debate and most likely depend on the injury severity and context2. The order of early regeneration-associated events is also controversially discussed, with some investigators stating that hepatic stellate cell activation and matrix remodeling is essential for generation of a LPC-favoring niche6, while others report that LPC expansion and the so-called Ductular Reaction are required to trigger fibrogenesis7. There are numerous animal models to study specific aspects of injury and regeneration, in an attempt to understand all the underlying factors that regulate disease progression and to ultimately develop new treatment strategies for patients8.
The choline-deficient and ethionine-supplemented (CDE) dietary model was originally developed for use in rats and later modified for chronic liver injury induction in mice9,10. Dietary deficiency of choline results in impaired assembly and secretion of very low-density lipoproteins. Combined with the hepatocarcinogen DL-ethionine, this regimen leads to excessive hepatic fat loading, continuous inflammation, periportal fibrosis, LPC response and long-term&#160;to hepatocellular carcinoma development11,12. However, importantly, different mouse strains exhibit distinctive patterns of inflammatory, fibrogenic and LPC response dynamics13. This protocol describes chronic liver injury induction in C57BL/6J mice, the most commonly used inbred mouse strain.
In chronic liver disease research, typical analyses include histological assessments by hematoxylin and eosin as well as Sirius Red staining to visualize collagen depositions, immunohistochemical, or immunofluorescent detection of hepatic cell populations, and transcriptomic analyses of the liver microenvironment that orchestrates the induced cellular changes through complex growth factor and cytokine networks14,15,16,17,18.

<table><tbody><tr><td>Six-week-old male C57BL/6J mice&amp;nbsp;</td><td>Animal Resource Centre of Western Australia, Murdoch, WA,&amp;nbsp; Australia</td><td>N/A</td><td></td></tr><tr><td>10 Kg Steam Cut Wheaten Chaff&amp;nbsp;</td><td>Specialty Feeds, Glen Forrest, WA, Australia&amp;nbsp;</td><td>N/A</td><td></td></tr><tr><td>Water for irrigation 1000ml bottle (Baxter)&amp;nbsp;</td><td>Surgical House, Perth, WA, Australia&amp;nbsp;</td><td>AHF7114A</td><td></td></tr><tr><td>Choline- deficient diet, modified (pellets)&amp;nbsp;</td><td>MP Biomedicals Australasia Pty Limited, WA, Australia 02960210</td><td></td><td></td></tr><tr><td>DL-Ethionine&amp;nbsp;</td><td>Sigma-Aldrich, Castle Hill, NSW,&amp;nbsp; Australia&amp;nbsp;</td><td>E5139-25G</td><td></td></tr><tr><td>Ketamil injection&amp;nbsp;</td><td>Troy Laboratories Pty Limited, Glendenning, NSW, Australia&amp;nbsp;</td><td>N/A</td><td></td></tr><tr><td>Ilum Xylazil-20 injection&amp;nbsp;</td><td>Troy Laboratories Pty Limited, Glendenning, NSW, Australia&amp;nbsp;</td><td>N/A</td><td></td></tr><tr><td>27G x 1/2&quot;, Regular Wall Needle&amp;nbsp;</td><td>Terumo Australia Pty Limited, NSW, Australia&amp;nbsp;</td><td>NN-2713R</td><td></td></tr><tr><td>Syringes Terumo 1ml and 10ml&amp;nbsp;</td><td>Terumo Australia Pty Limited, Macquarie Park, NSW, Australia&amp;nbsp;</td><td>1018242, 1018037</td><td></td></tr><tr><td>Tissue-Tek OCT compound&amp;nbsp;</td><td>VWR International Pty Limited, Tingalpa, QLD, Australia&amp;nbsp;</td><td>25608-930</td><td></td></tr><tr><td>Neutral buffered formalin&amp;nbsp;</td><td>Amber Scientific, Midvale, WA, Australia&amp;nbsp;</td><td>NBF-2.5L</td><td></td></tr><tr><td>Ethanol absolute anaLaR normalpur&amp;nbsp;</td><td>VWR International Pty Limited, Tingalpa, QLD, Australia&amp;nbsp;</td><td>20821.33</td><td></td></tr><tr><td>Superfrost Plus slides&amp;nbsp;</td><td>Grale Scientific Pty Limited, Ringwood, VIC, Australia&amp;nbsp;</td><td>SF41296SP</td><td></td></tr><tr><td>Dako Protein Block, serum-free&amp;nbsp;</td><td>Dako Australia Pty Limited, North Sydney, NSW, Australia&amp;nbsp;</td><td>&amp;nbsp;X090930-2</td><td></td></tr><tr><td>Dako antibody diluent&amp;nbsp;</td><td>Dako Australia Pty Limited, North Sydney, NSW, Australia&amp;nbsp;&amp;nbsp;</td><td>s0809</td><td></td></tr><tr><td>rat anti-CD45&amp;nbsp;</td><td>eBioscience, San Diego, California, USA&amp;nbsp;</td><td>m0701&amp;nbsp;</td><td>1/200 dilution</td></tr><tr><td>rabbit anti-panCK&amp;nbsp;</td><td>Dako Australia Pty Limited, North Sydney, NSW, Australia&amp;nbsp;&amp;nbsp;</td><td>Z0622</td><td>1/300 dilution</td></tr><tr><td>Goat anti-rabbit (Alexa Fluor 488)</td><td>Life Technologies Australia Pty Limited, Mulgrave, VIC, Australia</td><td>A-11008</td><td>1/500 dilution</td></tr><tr><td>Goat anti-rat IgG (Alexa Fluor 594)&amp;nbsp;</td><td>Life Technologies Australia Pty Limited, Mulgrave, VIC, Australia</td><td>&amp;nbsp;A-11007</td><td>1/500 dilution</td></tr><tr><td>ProLong Gold Antifade Reagent with DAPI&amp;nbsp;</td><td>Life Technologies Australia Pty Limited, Mulgrave, VIC, Australia&amp;nbsp;</td><td>P36935&amp;nbsp;&amp;nbsp;</td><td></td></tr><tr><td>Picrosirius Red Stain Kit</td><td>Polysciences Inc., Warrington, PA, USA&amp;nbsp;</td><td>ab150681&amp;emsp;</td><td></td></tr></tbody></table>

the murine choline-deficient, ethionine-supplemented (cde) diet model of chronic liver injury

Chronic liver diseases, such as viral hepatitis, alcoholic liver disease, or non-alcoholic fatty liver disease, are characterized by continual inflammation, progressive destruction and regeneration of the hepatic parenchyma, liver progenitor cell proliferation, and fibrosis. The end-stage of every chronic liver disease is cirrhosis, a major risk factor for the development of hepatocellular carcinoma. To study processes regulating disease initiation, establishment, and progression, several animal models are used in laboratories. Here we describe a six-week time course of the choline-deficient and ethionine-supplemented (CDE) mouse model, which involves feeding six-week old male C57BL/6J mice with choline-deficient chow and 0.15% DL-ethionine-supplemented drinking water. Monitoring of animal health and a typical body weight loss curve are explained. The protocol demonstrates the gross examination of a CDE-treated liver and blood collection by cardiac puncture for subsequent serum analyses. Next, the liver perfusion technique and collection of different hepatic lobes for standard evaluations are shown, including liver histology assessments by hematoxylin and eosin or Sirius Red stainings, immunofluorescent detection of hepatic cell populations as well as transcriptome profiling of the liver microenvironment. This mouse model is suitable for studying inflammatory, fibrogenic, and liver progenitor cell dynamics induced through chronic liver disease and can be used to test potential therapeutic agents that may modulate these processes.

Throughout the six-week time course of CDE-induced chronic liver injury, parameters were assessed on days 7 (induction phase), 14 and 21 (establishment phase) and 42 (maintenance phase). Compared to control mice, CDE-treated mice lost up to 20% of their initial body weight in an initial adaptation phase and tend to regain weight in the establishment and maintenance phases (Figure 1). The body weight was inversely correlated with serum alanine...

Watch this Scientific Journal Video about The Murine Choline-Deficient, Ethionine-Supplemented CDE Diet Model of Chronic Liver Injury at JoVE.com

The Murine Choline-Deficient, Ethionine-Supplemented CDE Diet Model of Chronic Liver Injury

Here we describe a common method to induce chronic liver injury in mice by feeding of a choline-deficient and ethionine-supplemented (CDE) diet. We demonstrate health monitoring, liver perfusion, isolation, and preservation. A time course of six weeks can inform about liver injury, pathohistology, fibrosis, inflammatory, and liver progenitor cell responses.

The Murine Choline-Deficient, Ethionine-Supplemented (CDE) Diet Model of Chronic Liver Injury

Chronic liver diseases, such as viral hepatitis, alcoholic liver disease, or non-alcoholic fatty liver disease, are characterized by continual ...

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Research

JoVE Journal

Biology

11.7K Views.  Curtin University. Hier beschrijven we een gemeenschappelijke methode om chronische lever schade in muizen door het eten van een dieet van choline-deficiënte en ethionine-aangevuld (CDE). We tonen gezondheidsmonitoring, lever perfusie, isolatie en behoud. Een tijdsverloop van zes weken kan informeren over de lever schade, pathohistology, fibrose, inflammatoire, en lever progenitor cel reacties.

Video: The Murine Choline-Deficient, Ethionine-Supplemented CDE Diet Model of Chronic Liver Injury

The CYP2D6 Animal Model: How to Induce Autoimmune Hepatitis in Mice

Autoimmune hepatitis is a rare but life threatening autoimmune disease of the liver of unknown etiology1,2. In the past many attempts have been made to generate an animal model that reflects the characteristics of the human disease 3-5. However, in various models the induction of disease was rather complex and often hepatitis was only transient3-5. Therefore, we have developed a straightforward mouse model that uses the major human autoantigen in type 2 autoimmune hepatitis (AIH-2), namely hCYP2D6, as a trigger6. Type 1 liver-kidney microsomal antibodies (LKM-1) antibodies recognizing hCYP2D6 are the hallmark of AIH-27,8. Delivery of hCYP2D6 into wildtype FVB or C57BL/6 mice was by an Adenovirus construct (Ad-2D6) that ensures a direct delivery of the triggering antigen to the liver. Thus, the ensuing local inflammation generates a fertile field9 for the subsequent development of autoimmunity. A combination of intravenous and intraperitoneal injection of Ad-2D6 is the most effective route to induce a long-lasting autoimmune damage to the liver (section 1). Here we provide a detailed protocol on how autoimmune liver disease is induced in the CYP2D6 model and how the different aspects of liver damage can be assessed. First, the serum levels of markers indicating hepatocyte destruction, such as aminotransferases, as well as the titers of hCYP2D6 antibodies are determined by sampling blood retroorbitaly (section 2). Second, the hCYP2D6-specific T cell response is characterized by collecting lymphocytes from the spleen and the liver. In order to obtain pure liver lymphocytes, the livers are perfused by PBS via the portal vein (section 3), digested in collagen and purified over a Percoll gradient (section 4). The frequency of hCYP2D6-specific T cells is analyzed by stimulation with hCYP2D6 peptides and identification of IFN&gamma;-producing cells by flow cytometry (section 5). Third, cellular infiltration and fibrosis is determined by immunohistochemistry of liver sections (section 6). Such analysis regimen has to be conducted at several times after initiation of the disease in order to prove the chronic nature of the model. The magnitude of the immune response characterized by the frequency and activity of hCYP2D6-specific T and/or B cells and the degree of the liver damage and fibrosis have to be assessed for a subsequent evaluation of possible treatments to prevent, delay or abrogate the autodestructive process of the liver.

Infection of mice with an Adenovirus expressing the major human autoantigen cytochrome P450 2D6 (hCYP2D6) recognized by sera of patients suffering from type 2 autoimmune hepatitis results in a persistent form of autoimmune-mediated liver disease characterized by extensive hepatitis, fibrosis and generation of a CYP2D6-specific immune response.

Autoimmune hepatitis is a rare but life threatening autoimmune disease of the liver of unknown etiology1,2. In the past many attempts have been made to ...

Medicine

A Familial Hypercholesterolemia Human Liver Chimeric Mouse Model Using Induced Pluripotent Stem Cell-derived Hepatocytes

Familial hypercholesterolemia (FH) is mostly caused by low-density lipoprotein receptor (LDLR) mutations and results in an increased risk of early-onset cardiovascular disease due to marked elevation of LDL cholesterol (LDL-C) in blood. Statins are the first line of lipid-lowering drugs for treating FH and other types of hypercholesterolemia, but new approaches are emerging, in particular PCSK9 antibodies, which are now being tested in clinical trials. To explore novel therapeutic approaches for FH, either new drugs or new formulations, we need appropriate in vivo models. However, differences in the lipid metabolic profiles compared to humans are a key problem of the available animal models of FH. To address this issue, we have generated a human liver chimeric mouse model using FH induced pluripotent stem cell (iPSC)-derived hepatocytes (iHeps). We used Ldlr-/-/Rag2-/-/Il2rg-/- (LRG) mice to avoid immune rejection of transplanted human cells and to assess the effect of LDLR-deficient iHeps in an LDLR null background. Transplanted FH iHeps could repopulate 5-10% of the LRG mouse liver based on human albumin staining. Moreover, the engrafted iHeps responded to lipid-lowering drugs and recapitulated clinical observations of increased efficacy of PCSK9 antibodies compared to statins. Our human liver chimeric model could thus be useful for preclinical testing of new therapies to FH. Using the same protocol, similar human liver chimeric mice for other FH genetic variants, or mutations corresponding to other inherited liver diseases, may also be generated.

Here, we present a protocol to generate a human liver chimeric mouse model of familial hypercholesterolemia using human induced pluripotent stem cell-derived hepatocytes. This is a valuable model for testing new therapies for hypercholesterolemia.

Familial hypercholesterolemia (FH) is mostly caused by low-density lipoprotein receptor (LDLR) mutations and results in an increased risk of early-onset ...

Developmental Biology

Bile Duct Ligation in Mice: Induction of Inflammatory Liver Injury and Fibrosis by Obstructive Cholestasis

In most vertebrates, the liver produces bile that is necessary to emulsify absorbed fats and enable the digestion of lipids in the small intestine as well as to excrete bilirubin and other metabolic products. In the liver, the experimental obstruction of the extrahepatic biliary system initiates a complex cascade of pathological events that leads to cholestasis and inflammation resulting in a strong fibrotic reaction originating from the periportal fields. Therefore, surgical ligation of the common bile duct has become the most commonly used model to induce obstructive cholestatic injury in rodents and to study the molecular and cellular events that underlie these pathophysiological mechanisms induced by inappropriate bile flow. In recent years, different surgical techniques have been described that either allow reconnection or reanastomosis after bile duct ligation (BDL), e.g., partial BDL, or other microsurgical methods for specific research questions. However, the most frequently used model is the complete obstruction of the common bile duct that induces a strong fibrotic response after 21 to 28 days. The mortality rate can be high due to infectious complications or technical inaccuracies. Here we provide a detailed surgical procedure for the BDL model in mice that induce a highly reproducible fibrotic response in accordance to the 3R rule for animal welfare postulated by Russel and Burch in 1959.

Disruption of bile flow results in severe inflammatory cholestatic liver injury with a characteristic time-dependent sequence of morphological alterations. Here we present a protocol for the surgical ligation of the common bile duct in mice that allows to induce a strong fibrotic response after 21 to 28 days.

In most vertebrates, the liver produces bile that is necessary to emulsify absorbed fats and enable the digestion of lipids in the small intestine as well ...

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.

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 ...

An Advanced Murine Model for Nonalcoholic Steatohepatitis in Association with Type 2 Diabetes

Obesity is associated with chronic low-grade inflammation and insulin resistance, contributing to an increasing prevalence of chronic metabolic diseases, such as type 2 diabetes and nonalcoholic steatohepatitis (NASH). Recent research has established that pro-inflammatory immune cells infiltrate obese hypertrophic adipose tissue and liver. Given the emerging importance of immune cells in the context of metabolic homeostasis, there is a critical need to quantify and characterize their modification during the development of type 2 diabetes and NASH. However, animal models that induce pathophysiological features typical of human NASH are sparse.
In this article, we provide a detailed protocol to identify immune cell subsets isolated from liver and adipose tissue in a reliable mouse model of NASH, established by housing high-fat diet (HFD) mice under non-specific pathogen-free (SPF) conditions without a barrier for at least seven weeks. We demonstrate the handling of mice in non-SPF conditions, digestion of the tissues and identification of macrophages, natural killer (NK) cells, dendritic cells, B and T cell subsets by flow cytometry. Representative flow cytometry plots from SPF HFD mice and non-SPF mice are provided. To obtain reliable and interpretable data, the use of antibodies, accurate and precise methods for tissue digestion and proper gating in flow cytometry experiments are critical elements.
The intervention to restore physiological antigen exposure in mice by housing them in non-SPF conditions and unspecific exposure to microbial antigens could provide a relevant tool for investigating the link between immunological alterations, diet-induced obesity and related long term complications.

A simple and reliable diet-induced rodent animal model for nonalcoholic steatohepatitis (NASH) is described, achieved through non-SPF housing of the animals and administration of a specific high-fat diet. We describe identification of hepatic and adipose immune cell subsets to recapitulate human immunological conditions by exposing mice to environmental germs.

Obesity is associated with chronic low-grade inflammation and insulin resistance, contributing to an increasing prevalence of chronic metabolic diseases, ...

Immunology and Infection

Generation of a Rat Model of Acute Liver Failure by Combining 70% Partial Hepatectomy and Acetaminophen

Acute liver failure (ALF) is a clinical condition caused by various etiologies resulting in the loss of metabolic, biochemical, synthesizing, and detoxifying functions of the liver. In most irreversible liver damage cases, orthotropic liver transplant (OLT) remains the only available treatment. To study the therapeutic potential of a treatment for ALF, its prior testing in an animal model of ALF is essential. In the current study, an ALF model in rats was developed by combining 70% partial hepatectomy (PHx) and injections of acetaminophen (APAP) that provides a therapeutic window of 48 h. The median and left lateral lobes of the liver were removed to excise 70% of the liver mass and APAP was given 24 h postsurgically for 2 days. Survival in ALF-induced animals was found to be severely decreased. The development of ALF was confirmed by altered serum levels of the enzymes alanine amino transferase (ALT), aspartate amino transferase (AST), alkaline phosphatase (ALP); changes in prothrombin time (PT); and assessment of the international normalized ratio (INR). Study of the gene expression profile by qPCR revealed an increase in expression levels of genes involved in apoptosis, inflammation, and in the progression of liver injury. Diffused degeneration of hepatocytes and infiltration of immune cells was observed by histological evaluation. The reversibility of ALF was confirmed by the restoration of survival and serum levels of ALT, AST, and ALP after intrasplenic transplantation of syngeneic healthy rat hepatocytes. This model presents a reliable alternative to the available ALF animal models to study the pathophysiology of ALF as well as to evaluate the potential of a novel therapy for ALF. The use of two different approaches also makes it possible to study the combined effect of physical and drug-induced liver injury. The reproducibility and feasibility of current procedure is an added benefit of the model.

The acute liver failure animal model developed in the current study presents a feasible alternative for the study of potential therapies. The current model employs the combined effect of physical and drug-induced hepatic injury and provides a suitable time window to study the potential of novel therapies.

Acute liver failure (ALF) is a clinical condition caused by various etiologies resulting in the loss of metabolic, biochemical, synthesizing, and ...

A Mouse Model of Chronic Liver Fibrosis for the Study of Biliary Atresia

Biliary atresia (BA) is a fatal disease involving obstructive jaundice, and it is the most common indication for liver transplantation in children. Due to the complex etiology and unknown pathogenesis, there are still no effective drug treatments. At present, the classic BA mouse model induced by rhesus rotavirus (RRV) is the most commonly used model for studying the pathogenesis of BA. This model is characterized by growth retardation, jaundice of the skin and mucosa, clay stools, and dark yellow urine. The histopathology shows severe liver inflammation and obstruction of the intrahepatic and extrahepatic bile ducts, which are similar to the symptoms of human BA. However, the livers of end-stage mice in this model lack fibrosis and cannot fully simulate the characteristics of liver fibrosis in clinical BA. The presented study developed a novel BA mouse model of chronic liver fibrosis by injecting 5-10 &#181;g of anti-Ly6G antibody four times, with gaps of 2 days after each injection. The results showed that some of the mice successfully formed chronic BA with typical fibrosis after the time lapse, meaning these mice represent a suitable animal model for the virus-induced liver fibrosis mechanistic study of BA and a platform for developing future BA treatments.

We established a mouse model of chronic liver fibrosis, which provides a suitable animal model for the virus-induced liver fibrosis mechanistic study of biliary atresia (BA) and a platform for future BA treatments.

Biliary atresia (BA) is a fatal disease involving obstructive jaundice, and it is the most common indication for liver transplantation in children. Due to ...

Vinyl Chloride and High-Fat Diet as a Model of Environment and Obesity Interaction

Vinyl chloride (VC), an abundant environmental contaminant, causes steatohepatitis at high levels, but is considered safe at lower levels. Although several studies have investigated the role of VC as a direct hepatotoxicant, the concept that VC modifies sensitivity of the liver to other factors, such as nonalcoholic fatty liver disease (NAFLD) caused by high-fat diet (HFD) is novel. This protocol describes an exposure paradigm to evaluate the effects of chronic, low-level exposure to VC. Mice are acclimated to low-fat or high-fat diet one week prior to the beginning of the inhalation exposure and remain on these diets throughout the experiment. Mice are exposed to VC (sub-OSHA level: &#60;1 ppm) or room air in inhalation chambers for 6 hours/day, 5 days/week, for up to 12 weeks. Animals are monitored weekly for body weight gain and food consumption. This model of VC exposure causes no overt liver injury with VC inhalation alone. However, the combination of VC and HFD significantly enhances liver disease. A technical advantage of this co-exposure model is the whole-body exposure, without restraint. Moreover, the conditions more closely resemble a very common human situation of a combined exposure to VC with underlying nonalcoholic fatty liver disease and therefore support the novel hypothesis that VC is an environmental risk factor for the development of liver damage as a complication of obesity (i.e., NAFLD). This work challenges the paradigm that the current exposure limits of VC (occupational and environmental) are safe. The use of this model can shed new light and concern on the risks of VC exposure. This model of toxicant-induced liver injury can be used for other volatile organic compounds and to study other interactions that may impact the liver and other organ systems.

The goal of this protocol was to develop a murine model of low-level toxicant exposure that does not cause overt liver injury but rather exacerbates pre-existing liver damage. This paradigm better recapitulates human exposure and the subtle changes that occur upon exposure to toxicant concentrations that are considered safe.

Vinyl chloride (VC), an abundant environmental contaminant, causes steatohepatitis at high levels, but is considered safe at lower levels. Although ...

Inducing Acute Liver Injury in Rats via Carbon Tetrachloride (CCl4) Exposure Through an Orogastric Tube

Acute liver injury (ALI) plays a crucial role in the development of hepatic failure, which is characterized by severe liver dysfunction including complications such as hepatic encephalopathy and impaired protein synthesis. Appropriate animal models are vital to test the mechanism and pathophysiology of ALI and investigate different hepatoprotective strategies. Due to its ability to perform chemical transformations, carbon tetrachloride (CCl4) is widely used in the liver to induce ALI through the formation of reactive oxygen species. CCl4 exposure can be performed intraperitoneally, by inhalation, or through a nasogastric or orogastric tube. Here, we describe a rodent model, in which ALI is induced by CCl4 exposure through an orogastric tube. This method is inexpensive, easily performed, and has minimal hazard risk. The model is highly reproducible and can be widely used to determine the efficacy of potential hepatoprotective strategies and assess markers of liver injury.

Inducing Acute Liver Injury in Rats via Carbon Tetrachloride CCl4 Exposure Through an Orogastric Tube

This protocol describes a common and feasible method of inducing acute liver injury (ALI) via CCl4 exposure through an orogastric tube. CCl4 exposure induces ALI through the formation of reactive oxygen species during its biotransformation in the liver. This method is used to analyze the pathophysiology of ALI and examine different hepatoprotective strategies.

Acute liver injury (ALI) plays a crucial role in the development of hepatic failure, which is characterized by severe liver dysfunction including ...

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 ...

The Murine Choline-Deficient, Ethionine-Supplemented (CDE) Diet Model of Chronic Liver Injury

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