We thank Hyesuk Park for the technical help. This research was supported by funding from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), NIH (R01 2DK083283, to NJT), the National Institute on Aging (NIA), NIH (1R01AG060726, to NJT).&#160;We gratefully acknowledge Jon Mulholland and Kitty Lee of the Cell Sciences Imaging Facility in the Beckman Center for technical assistance with the two-photon microscopy imaging.&#160;

Animal experiments are performed according to the experimental procedures approved by the institutional animal care and use committees (IACUCs) of Stanford University and the Veterans Affairs Hospital in Palo Alto. 6-8 week-old male C57BL/6J mice were fed either chow or a fast-food diet supplemented with 4.2% high-fructose corn syrup (see Table of Materials) in drinking water for 14 weeks5. The mice were kept in standard cages at a 12 h dark/light cycle.
...

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B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanisms+of+fibrosis+development+in+non-alcoholic+steatohepatitis.">Mechanisms of fibrosis development in non-alcoholic steatohepatitis.</a> Gastroenterology. 158 (7), 1913-1928 (2020).</li><li>Arteel, G. E., Naba, 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+liver+matrisome+-+looking+beyond+collagens.">The liver matrisome - looking beyond collagens.</a> JHEP Reports. 2 (4), 100115 (2020).</li><li>Jiang, J. X., 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=Nonphagocytic+activation+of+NOX2+is+implicated+in+progressive+non-alcoholic+steatohepatitis+during+aging.">Nonphagocytic activation of NOX2 is implicated in progressive non-alcoholic steatohepatitis during aging.</a> Hepatology. 72 (4), 1204-1218 (2020).</li><li>Dehnad, 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=AGER1+downregulation+associates+with+fibrosis+in+non-alcoholic+steatohepatitis+and+type+2+diabetes.">AGER1 downregulation associates with fibrosis in non-alcoholic steatohepatitis and type 2 diabetes.</a> Journal of Clinical Investigation. 130 (8), 4320-4330 (2020).</li><li>Mayorca-Guiliani, A. 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=Decellularization+and+antibody+staining+of+mouse+tissues+to+map+native+extracellular+matrix+structures+in+3D.">Decellularization and antibody staining of mouse tissues to map native extracellular matrix structures in 3D.</a> Nature Protocols. 14 (12), 3395-3425 (2019).</li><li>Mazza, 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=Cirrhotic+human+liver+extracellular+matrix+3D+scaffolds+promote+smad-dependent+tgf-beta1+epithelial+mesenchymal+transition.">Cirrhotic human liver extracellular matrix 3D scaffolds promote smad-dependent tgf-beta1 epithelial mesenchymal transition.</a> Cells. 9 (1), 83 (2019).</li><li>Klaas, 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=The+alterations+in+the+extracellular+matrix+composition+guide+the+repair+of+damaged+liver+tissue.">The alterations in the extracellular matrix composition guide the repair of damaged liver tissue.</a> Scientific Reports. 6, 27398 (2016).</li><li>Mattei, 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=Mechanostructure+and+composition+of+highly+reproducible+decellularized+liver+matrices.">Mechanostructure and composition of highly reproducible decellularized liver matrices.</a> Acta Biomaterialia. 10 (2), 875-882 (2014).</li><li>Ren, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+two+decellularization+methods+in+the+development+of+a+whole-organ+decellularized+rat+liver+scaffold.">Evaluation of two decellularization methods in the development of a whole-organ decellularized rat liver scaffold.</a> Liver International. 33 (3), 448-458 (2013).</li><li>Piersma, B., Hayward, M. 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The authors declare that there are no conflicts of interest regarding this article.

The present protocol shows that decellularization through a low flow rate DOC in situ perfusion preserves the frangible triple-helical and native fibrillar collagen structures, providing a reliable and cost-effective platform to capture dynamic ECM remodeling in NASH liver fibrosis. Although decellularization was performed in normal and fibrotic livers before identifying ECM components or generating biological scaffolds for cell culture, the dynamics of ECM remodeling in liver fibrosis have not been well studied...

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease, affecting 20%-25% of the adult population. 25% of NAFLD patients progress to non-alcoholic steatohepatitis (NASH), where the risk of cirrhosis, liver failure, and hepatocellular carcinoma increases1. In the next 20 years, it is estimated that NASH will account for 2 million liver-related deaths in U.S2. As there are no approved treatments, there is an urgent need to decipher the mechanisms that cause liver fibrosis in NASH patients and develop targeted treatment3.
The extracellular matrix (ECM) is a dynamic, complex microenvironment that exerts bi-directional communication with cells to regulate tissue homeostasis4. The liver ECM is composed of structural elements such as proteoglycans, collagens, fibronectin, elastin, and other non-structural proteins (e.g., olfactomedin and thrombospondin) to provide physical and structural support4.
Liver fibrosis is a chronic wound-healing response to liver damage of various etiologies, including NASH3. It results from an imbalance in the dynamic ECM matrix remodeling process and is characterized by excessive structural proteins in the injured liver4. Fibrogenesis depends on the dynamic cell-cell communication among different hepatic cell types. Hepatic stellate cells (HSCs),&#160;when activated, differentiate into Smooth Muscle Alpha 2 Actin-expressing, migrating, and proliferating myofibroblast-like cells and synthesize ECM proteins as a wound-closing action. Activated HSCs are the central collagen-producing cells in the liver1.
The molecular mechanism of ECM remodeling, patterns of fibrosis, and their relationship with cellular events are not clear. A better understanding of the three-dimensional (3D)&#160;ECM structure is still needed, even though mass spectrometry techniques have helped analyze ECM protein composition4. Traditionally, Masson&#39;s trichrome stain, Picro Sirius Red stains, and second harmonic generation (SHG) imaging have been performed on two-dimensional (2D) thin liver sections. The typical fibrosis pattern of NASH is called &#34;chicken wire,&#34; which extends to zone 3 and is perisinusoidal/pericellular fibrosis5,6. However, there has been a lack of studies focusing on the 3D structure of the native liver, particularly those that do not involve tissue sectioning. Robust imaging approaches to identify patterns and characteristics of fibrosis throughout dynamic ECM remodeling in liver fibrosis would significantly strengthen the understanding of NASH mechanisms and identify new therapeutic targets.
To address these challenges, a fast and efficient protocol was optimized to image the native liver ECM via decellularization7. Whole-liver decellularization is an approach to remove the hepatic cellular content while maintaining the native 3D ECM network through detergent perfusion. Mice were fed either chow or fast-food diet (FFD) for 14 weeks. Decellularization was performed after in situ portal vein perfusion with mild detergent and low flow rates to preserve triple-helical and native fibrillar collagen structures. Two-photon microscopy was applied to analyze changes in collagen structures in ECM. The 3D images of the native ECM structure in normal and NASH livers were reconstituted and analyzed. Performing in situ perfusion decellularization and analyzing the scaffold by two-photon microscopy provides a practical and affordable platform to visualize the dynamic ECM remodeling in the liver.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>4-0 MONOCRYL UNDYED 1 x 18&#34; P-3</td>
			<td>MONOCRYL</td>
			<td>Y494G</td>
			<td></td>
		</tr>
		<tr>
			<td>4-0 suture</td>
			<td>fisher scientific</td>
			<td>10-000-649</td>
			<td>https://www.fishersci.com/shop/products/monomid-nylon-non-absorbable-sutures-7/10000649?keyword=true</td>
		</tr>
		<tr>
			<td>AnaSed Injection (xylazine)</td>
			<td>AnaSed</td>
			<td>NDC 59399-110-20</td>
			<td>this drug to use by or on the order of a licensed veterinarian.</td>
		</tr>
		<tr>
			<td>BD INSYTE AUTOGUARD I.V. CATHETER WITH BC TECHNOLOGY</td>
			<td>BD</td>
			<td>382612</td>
			<td></td>
		</tr>
		<tr>
			<td>Chow diet</td>
			<td>Envigo</td>
			<td># 2918</td>
			<td>Control diet. A fixed formula, non-autoclavable diet manufactured with high quality ingredients and designed to support gestation, lactation, and growth of rodents.</td>
		</tr>
		<tr>
			<td>Fast-food diet (AIN76A Western Diet)</td>
			<td>Test Diet</td>
			<td>1810060</td>
			<td>https://www.testdiet.com/cs/groups/lolweb/@testdiet/documents/web_content/mdrf/mdux/~edisp/ducm04_051601.pdf</td>
		</tr>
		<tr>
			<td>Hematoxylin and Eosin Stain Kit</td>
			<td>vectorlabs</td>
			<td>H-3502</td>
			<td>https://vectorlabs.com/hematoxylin-and-eosin-stain-kit.html</td>
		</tr>
		<tr>
			<td>Kent Scientific Rat Surgical Kit</td>
			<td>fisher scientific</td>
			<td>13-005-205</td>
			<td>https://www.fishersci.com/shop/products/rat-surgical-kit/13005205#?keyword=mouse%20surgery%20kit</td>
		</tr>
		<tr>
			<td>KETAMINE HYDROCHLORIDE INJECTION</td>
			<td>Vedco</td>
			<td>NDC 50989-996-06 - 10 mL - vial.</td>
			<td>KetaVed has been clinically studied in subhuman primates in addition to those species listed under Administration and Dosage.</td>
		</tr>
		<tr>
			<td>Leica SP5 upright Confocal, multi-photon</td>
			<td>Leica</td>
			<td>SP5</td>
			<td></td>
		</tr>
		<tr>
			<td>Luer connector (Three-way stopcock with SPIN-LOCK&#174;)</td>
			<td>bbraun</td>
			<td>D300</td>
			<td>https://www.bbraunusa.com/en/products/b0/three-way-stopcockwithspin-lock.html</td>
		</tr>
		<tr>
			<td>Picrosirius Red Stain Kit</td>
			<td>Polysciences, Inc.</td>
			<td>24901</td>
			<td>https://www.polysciences.com/default/picrosirius-red-stain-kit-40771</td>
		</tr>
		<tr>
			<td>Rayon tipped applicator</td>
			<td>puritan</td>
			<td>25-806 1PR</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium deoxycholate</td>
			<td>sigmaaldrich</td>
			<td>D6750-100G</td>
			<td></td>
		</tr>
		<tr>
			<td>Syrup</td>
			<td>www.target.com</td>
			<td>24 fl oz</td>
			<td>https://www.target.com/p/pancake-syrup-24-fl-oz-market-pantry-8482/-/A-13007801</td>
		</tr>
		<tr>
			<td>Variable Speed Peristaltic Pump</td>
			<td>INTLLAB</td>
			<td>BT100</td>
			<td>https://www.amazon.com/gp/product/B082K97W5W/ref=ox_sc_saved_title_2?smid=A12NUUP87ZRRAR&#38;psc=1</td>
		</tr>
		<tr>
			<td>VECTASHIELD Antifade Mounting Medium</td>
			<td>vectorlabs</td>
			<td>H-1000-10</td>
			<td>https://vectorlabs.com/vectashield-mounting-medium.html</td>
		</tr>
	</tbody>
</table>

3d imaging of the liver extracellular matrix in a mouse model of non-alcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH) is the most common chronic liver disease in the United States, affecting more than 70 million Americans. NASH can progress to fibrosis and eventually to cirrhosis, a significant risk factor for hepatocellular carcinoma. The extracellular matrix (ECM) provides structural support and maintains liver homeostasis via matricellular signals. Liver fibrosis results from an imbalance in the dynamic ECM remodeling process and is characterized by excessive accumulation of structural elements and associated changes in glycosaminoglycans. The typical fibrosis pattern of NASH is called &#34;chicken wire,&#34; which usually consists of zone 3 perisinusoidal/pericellular fibrosis, based on features observed by Masson&#39;s trichrome stain and Picrosirius Red stains. However, these traditional thin two-dimensional (2D) tissue slide-based imaging techniques cannot demonstrate the detailed three-dimensional (3D) ECM structural changes, limiting the understanding of the dynamic ECM remodeling in liver fibrosis.
The current work optimized a fast and efficient protocol to image the native ECM structure in the liver via decellularization to address the above challenges. Mice were fed either with chow or fast-food diet for 14 weeks. Decellularization was performed after in situ portal vein perfusion, and the two-photon microscopy techniques were applied to image and analyze changes in the native ECM. The 3D images of the normal and NASH livers were reconstituted and analyzed. Performing in situ perfusion decellularization and analyzing the scaffold by two-photon microscopy provided a practical and reliable platform to visualize the dynamic ECM remodeling in the liver.

The collagen fibers were detected with second harmonic generation and two-photon microscopy. The signal is from the frangible triple-helical and native fibrillar collagen structures. Specific antibodies were not used to analyze collagen subtypes; however, this could be added to the imaging&#160;technique.
When the liver tissue is studied without decellularization, it is challenging to get high-resolution images of the collagen network (Figure 5A)....

Watch this Scientific Journal Video about 3D Imaging of the Liver Extracellular Matrix in a Mouse Model of Non-Alcoholic Steatohepatitis at JoVE.com

3D Imaging of the Liver Extracellular Matrix in a Mouse Model of Non-Alcoholic Steatohepatitis

The present protocol optimizes the liver in situ perfusion/decellularization and two-photon microscopy methods to establish a reliable platform to visualize the dynamics of extracellular matrix (ECM) remodeling during non-alcoholic steatohepatitis (NASH).

Non-alcoholic steatohepatitis (NASH) is the most common chronic liver disease in the United States, affecting more than 70 million Americans. NASH can ...

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1.6K Views.  Stanford University. The present protocol optimizes the liver in situ perfusion/decellularization and two-photon microscopy methods to establish a reliable platform to visualize the dynamics of extracellular matrix (ECM) remodeling during non-alcoholic steatohepatitis (NASH).