The authors have no acknowledgements.

All experiments in this protocol were approved by the Veterinary Authorities of the Canton of Z&#252;rich, Switzerland (number 60/2014). Furthermore, all experimental steps were performed in strict compliance with the Guidelines on Experiments with Animals by the Swiss Academy of Medical Sciences (SAMS) and Guidelines of the Federation of European Laboratory Animal Science Associations (FELASA).
1. Animal Husbandry, Operating Room Equipment and Instruments, Anesthesia
<ol>
	<li>Keep male Wistar rats with a weight of 250-300 g in ventilated cages under standard pathogen-free conditions in a 12/12 h light/dark cycle. Give animals free access to food and water at an ambient temperature of 22 &#177; 1 &#176;C.</li>
	<li>Induce anesthesia in a box, where isoflurane is flushed in with 5 vol% for 30 s (Figure 1A), followed by an isoflurane concentration of 3 vol% until the animal is under deep anesthesia. Confirm the level of anesthesia by the toe-pinch reflex.</li>
	<li>Provide analgesia using subcutaneously applied buprenorphine (0.01 mg/kg) during the surgical intervention, followed by 0.02 mg/kg every 12 h in the postoperative phase for 48 h.</li>
	<li>Transfer the animal to the working place, where they are spontaneously breathing exposed to a gas mixture of 1.0 - 2.5 vol% isoflurane in oxygen (flow: 600 mL/min).</li>
	<li>Close the eyes of the animal and use an ointment to protect the eyes. Inject 5 mL saline subcutaneously, half of it on each side of the abdomen, followed by 0.1 mg atropine.</li>
	<li>Perform surgery using a surgical microscope in a microsurgery room.</li>
	<li>Keep the animal under volatile anesthesia using a ventilation mask consisting of a latex membrane (Figure 1B), through which the rat&#39;s snout is pushed. Fix the extremities with tape (Figure 1B).</li>
	<li>Lay out the surgical instruments in sterile fashion on a side table: saline- and Betadine-soaked sponges (Figure 2A), abdominal wall retractors (Figure 2B) as well as 3-0 sutures for retraction of the abdominal wall and xiphoid, scissors, Adson forceps, fine tips microforceps straight and curved and pre-cut 6-0 silk ties for the ligation procedure (Figure 2C).</li>
	<li>Use non-sticking bipolar microforceps for transection of the hepatic parenchyma. Close the abdominal wall and skin using 3-0 silk sutures with SH-1 needles and 5-0 Maxon (Figure 2D). Use a bipolar forceps for hemostasis.</li>
</ol>
2. Start of Surgery
<ol>
	<li>Shave the abdomen of the animal with a small animal hair clipper from the xiphoid to the genitals with a 2-cm area lateral of the midline. Thoroughly remove the hair.</li>
	<li>Disinfect this area 3 times with betadine soaked sponges.</li>
	<li>Perform a midline incision using a scalpel for the skin, and then use surgical scissors to open the abdomen.</li>
	<li>Retract the right and left abdominal wall and the xiphoid with 3-0 silk sutures (Figure 3A).</li>
	<li>Retract the stomach, colon and small bowel from the hepatoduodenal ligament of the rat with self-made small wire retractors (Figure 3B).</li>
</ol>
3. Portal Vein Ligation (PVL)
<ol>
	<li>Access the portal vein and its branches by lateral retraction of the stomach and the small bowel (Figure 3B).</li>
	<li>Dissect the portal vein bluntly by picking up the peritoneum with the microforceps and slowly peeling it medially.</li>
	<li>Dissect the portal vein branches out (Figure 3C) in the following sequence: (1) right posterior branch, (2) left lateral and left median branch together, and (3) caudate branch.
	<ol>
		<li>First, peel off the peritoneum with small, not too energetic moves to avoid tearing the small arterial branches to the liver lobes that run directly under the peritoneal coverage.</li>
		<li>Once the main portal vein is denuded, encircle the branches with slow forward pushing and spreading movements and then pull a 1-cm piece of 6-0 silk tie around the respective portal vein branch and ligate it.</li>
	</ol>
	</li>
	<li>Ligate the right posterior lobe branch. (Figure 3C) The technical difficulty of the right posterior branch consists in the fact that the artery to the right posterior lobe is running across the right posterior portal vein branch.
	<ol>
		<li>Pull the artery cranially together with the peritoneum to expose the right portal vein branch with the curved microforceps.</li>
		<li>Ligate the right posterior lobe branch with the pre-cut 6-0 silk tie. The right posterior lobe turns visibly pale once the portal vein is ligated.</li>
		<li>Avoid pushing against resistance during the circling to prevent tearing the artery or the portal vein. In case of bleeding, apply pressure for at least one minute with a sterile cotton swab and then reassess. If bleeding does not stop, sacrifice the animal.</li>
	</ol>
	</li>
	<li>Ligate the left lateral (LLL) and left median lobe (LML) branches. These branches have one common trunk. (Figure 3C). The left median lobe branch arises from the portal vein within the parenchyma of the LLL.
	<ol>
		<li>Ligate the portal vein leading to both LLL and also the LML branch together using the pre-cut 6-0 silk tie.</li>
		<li>Avoid injuries to the arteries leading to LLL and LML, running within the peritoneal layer. As long as the peritoneum is peeled back carefully, they stay intact. The LLL and LML turn visibly pale once the branches are ligated.</li>
	</ol>
	</li>
	<li>Ligate the caudate lobe branch (Figure 3C). The portal vein leading to the somewhat separate caudate lobes in rats takes off from the main portal vein, distally and medially to the takeoff of the right lobe branch from the main portal vein (not strictly inferiorly like in humans or larger animals).
	<ol>
		<li>Dissect it out and encircle it by lifting up the peritoneum plus bile duct and arteries from the main portal vein.</li>
		<li>Encircle the caudate portal vein branch with a curved microforceps coming from laterally. The two caudate lobes turn visibly pale, once the caudate lobe branch is ligated with 6-0 silk.</li>
	</ol>
	</li>
	<li>Tying these three portal vein branches leads to exclusive portal vein perfusion of the right median lobe (RML), which is visible by a distinct demarcation line between the right and left median lobe.</li>
</ol>
4. Portal Vein Ligation with Transection (PVL+T)
<ol>
	<li>Perform the transection along the demarcation line between RML and LML after PVL (Figure 3D).</li>
	<li>Use a non-sticking bipolar silver forceps with a very fine neurosurgical tip to precauterize the liver tissue creating a 1-mm cauterization strip along the demarcation line.</li>
	<li>Use scissors to carefully cut the precauterized tissue. It is quite difficult to properly assess the depth of the transection. The goal is to get as close to the vena cava as possible, which runs intrahepatically in rats. Injury of the vena cava is accompanied by extensive bleeding, which can usually not be stopped.</li>
	<li>In case of injury apply gentle pressure using a cotton-swab, but if the bleeding does not stop within 3 - 4 min, sacrifice the animal. Attempts at repairing the vena cava using sutures have generally been unsuccessful. Rats are very sensitive to air embolism, which may occur on occasion and lead to cardiac arrest.</li>
</ol>
5. Intraoperative Measurement of Portal Vein Pressure and Volume Flow
<ol>
	<li>Assess portal vein pressure by direct cannulation with a G30 needle connected to a pressure monitor (Figure 4A).</li>
	<li>Use the 2-mm volume flow probe placed laterally connected to the flow device for direct measurement of portal volume flow over 2 min (Figure 4B). Only record data with stable measurement quality as indicated on the machine display.</li>
	<li>Assess portal vein flow and pressure separately after the group of steps that define the respective procedure, i.e. the tying off of three portal vein branches or the tying off of the three portal vein branches plus performing the parenchymal transection between the RML and the LML.</li>
</ol>
6. Final Steps of Surgery
<ol>
	<li>Make sure that the small bowel is placed properly in the abdominal cavity before closing.</li>
	<li>Close the peritoneum and the abdominal wall with 3-0 silk sutures with SH-1 needles.</li>
	<li>Finally suture the skin using Maxon 5-0.</li>
	<li>Disinfect the skin again.</li>
	<li>Apply again 5 mL saline subcutaneously into the subcutaneous tissue lateral to the abdomen.</li>
</ol>
7. Liver Volumetry in Rats Using Small Animal CT
<ol>
	<li>24 h prior to the first CT imaging inject 200 &#956;L of the contrast agent into the tail vein through a G26 intravenous catheter.</li>
	<li>Use a micro CT to scan the rats. Place the animal in a plexiglas box to induce general anesthesia (first flush in with 5 vol% for 30 s, followed by an isoflurane concentration of 2 - 3 vol% until the animal is under anesthesia and maintain it throughout scanning via a tubing system). For optimal image quality, synchronize the CT scan with the respiration of the animal.</li>
	<li>Export the digital imaging and communications in medicine (DICOM) files and analyze them using the public domain imaging platform OsiriX 8.0. Use the &#34;closed polygon&#34; tool to draw the lobe borders based on the radiodensitiy of the nanoparticle contrast in the liver and use the region of interest (ROI) menu to calculate partial liver volumes (see Figure 2A in Schadde et al.17)</li>
	<li>In the standard model, allow the liver to grow over 3 days and obtain daily CT scans to assess volume increase.</li>
</ol>

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Similar Regenerative Response?.</a> PLoS One. 10 (12), e0144096 (2015).</li><li>Shi, 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=A+preliminary+study+of+ALPPS+procedure+in+a+rat+model.">A preliminary study of ALPPS procedure in a rat model.</a> Sci Rep. 5, 17567 (2015).</li><li>Almau Trenard, H. 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=Development+of+an+experimental+model+of+portal+vein+ligation+associated+with+parenchymal+transection+(ALPPS)+in+rats.">Development of an experimental model of portal vein ligation associated with parenchymal transection (ALPPS) in rats.</a> Cir Esp. 92 (10), 676-681 (2014).</li><li>Dhar, D. K., Mohammad, G. H., Vyas, S., Broering, D. C., Malago, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+rat+model+of+liver+regeneration:+possible+role+of+cytokine+induced+neutrophil+chemoattractant-1+in+augmented+liver+regeneration.">A novel rat model of liver regeneration: possible role of cytokine induced neutrophil chemoattractant-1 in augmented liver regeneration.</a> Ann Surg Innov Res. 9, 11 (2015).</li><li>Wei, W., 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=Establishment+of+a+rat+model:+Associating+liver+partition+with+portal+vein+ligation+for+staged+hepatectomy.">Establishment of a rat model: Associating liver partition with portal vein ligation for staged hepatectomy.</a> Surgery. 159 (5), 1299-1307 (2016).</li><li>Tschuor, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Salvage+parenchymal+liver+transection+for+patients+with+insufficient+volume+increase+after+portal+vein+occlusion+-+an+extension+of+the+ALPPS+approach.">Salvage parenchymal liver transection for patients with insufficient volume increase after portal vein occlusion - an extension of the ALPPS approach.</a> Eur J Surg Oncol. 39 (11), 1230-1235 (2013).</li><li>Schadde, 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=Early+survival+and+safety+of+ALPPS:+first+report+of+the+International+ALPPS+Registry.">Early survival and safety of ALPPS: first report of the International ALPPS Registry.</a> Ann Surg. 260 (5), 829-836 (2014).</li><li>Harnoss, J. 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=Prolyl+Hydroxylase+Inhibition+Enhances+Liver+Regeneration+Without+Induction+of+Tumor+Growth.">Prolyl Hydroxylase Inhibition Enhances Liver Regeneration Without Induction of Tumor Growth.</a> Ann Surg. , (2016).</li><li>Olthof, P. 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=Comparable+liver+function+and+volume+increase+after+portal+vein+embolization+in+rabbits+and+humans.">Comparable liver function and volume increase after portal vein embolization in rabbits and humans.</a> Surgery. 161 (3), 658-665 (2017).</li><li>Olthof, P. B., van Gulik, T. M., Bennink, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimal+use+of+hepatobiliary+scintigraphy+before+liver+resection.">Optimal use of hepatobiliary scintigraphy before liver resection.</a> HPB (Oxford). 18 (10), 870 (2016).</li><li>Lau, L., Christophi, C., Muralidharan, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intraoperative+functional+liver+remnant+assessment+with+indocyanine+green+clearance:+another+toehold+for+climbing+the+&amp;#34;ALPPS&amp;#34;.">Intraoperative functional liver remnant assessment with indocyanine green clearance: another toehold for climbing the &amp;#34;ALPPS&amp;#34;.</a> Ann Surg. 261 (2), e43-e45 (2015).</li><li>Cieslak, K. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessment+of+Liver+Function+Using+(99m)Tc-Mebrofenin+Hepatobiliary+Scintigraphy+in+ALPPS+(Associating+Liver+Partition+and+Portal+Vein+Ligation+for+Staged+Hepatectomy).">Assessment of Liver Function Using (99m)Tc-Mebrofenin Hepatobiliary Scintigraphy in ALPPS (Associating Liver Partition and Portal Vein Ligation for Staged Hepatectomy).</a> Case Rep Gastroenterol. 9 (3), 353-360 (2015).</li><li>Truant, 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=Drop+of+Total+Liver+Function+in+the+Interstages+of+the+New+Associating+Liver+Partition+and+Portal+Vein+Ligation+for+Staged+Hepatectomy+Technique:+Analysis+of+the+&amp;#34;Auxiliary+Liver&amp;#34;+by+HIDA+Scintigraphy.">Drop of Total Liver Function in the Interstages of the New Associating Liver Partition and Portal Vein Ligation for Staged Hepatectomy Technique: Analysis of the &amp;#34;Auxiliary Liver&amp;#34; by HIDA Scintigraphy.</a> Ann Surg. 263 (3), e33-e34 (2016).</li></ol>

The authors have nothing to disclose.

This protocol presents an animal model of ALPPS with its rapid hypertrophy induced by PVL+T, that roughly doubles volume increase within 3 days compared to PVL alone.17 The right middle hepatic lobe is used as a model for the growing liver lobe because the middle hepatic lobe is one contiguous parenchymal mass supplied by two separate portal veins to its left and to its right side, as shown in Figure 1 in a recently published work.17 Compared t...

The size of the liver remnant limits the resectability of liver tumors.1 In general, when less than 25% liver tissue is left behind, the patient is at increased risk of death from acute liver failure due to the lack of metabolic function for the entire organism (&#34;too small for size syndrome&#34;).2 This post-hepatectomy liver failure is the most devastating complication after liver resection. Therefore clinicians have tried to induce liver regeneration prior to resection of the liver by manipulating the flow of the portal vein.3 It was found that, once the portal vein is occluded, the remaining part with portal vein flow starts to grow at a slow rate, and can thereby increase up to 60% in size.4 Surgical ligation5 or interventional portal vein occlusion have both been clinically established.4 The increase in volume and function of the liver is reliable, but the growth rate of the liver after portal occlusion is only about one fifth compared to the growth of the remnant liver after partial hepatectomy.6
The time necessary for the liver to grow is weeks to months even though the liver can regenerate at a much faster rate after resection. As such, the liver is the only organ that grows back to normal function after removal of a part of it.7 A novel procedure inducing liver regeneration at a similar pace as after partial hepactectomy was developed by a group of surgeons who discovered that adding a transection between the occluded and the non-occluded part of the liver induces liver hypertrophy at the same growth rate as after liver resection, but prior to resection.9 The procedure initiates rapid hypertrophy of 80% within a week in the future liver remnant, which allows the resection of extensive, primarily unresectable, liver tumors within a week. The procedure was called &#34;Associating Liver Partition and Portal vein ligation for Staged hepatectomy = ALPPS&#34; and became rapidly popular across the world.10 Multiple reports supported an expansion of the resectability of borderline resectable liver tumors achieved by the new technique,11 while the complex surgical procedure was also criticized for its high complication rate.12,13
The development of a rodent and also large animal models of slow and rapid hypertrophy has been attempted since the publication of ALPPS in 2012 to allow a better histological characterization and understanding of the mechanisms and to test drug effects on the different growth rates of liver tissue in animals. The first animal model developed was a rat model. In this model, rapid hypertrophy after parenchymal transection between the right and the left part of the median lobe accelerated regeneration of the right median lobe.14 A different model was introduced later in the mouse. In this model the left lateral lobe was resected and the portal vein branches to every lobe of the liver except the left median lobe were tied.15 In the meantime, large animal models of ALPPS in pigs have been described as well.16
For the study of physiological mechanisms like flow changes and pressure in the portal vein, perfusion and oxygenation of liver tissue, the rat model is superior to the model of ALPPS in mice. Another advantage of the rat over the murine model is that in the rat model there is no necessity for a resection of the left lateral lobe,15 which may contaminate the effects of liver resection with those of ALPPS. The rat model in contrast does not reduce the liver cell mass. A pig model uses the right posterior lobe as the growing lobe, but the pig liver is highly lobulated. Therefore, it is difficult to create a transection plane in the already thin tissue bridge between the right posterior and the right anterior lobe. In contrast, the median lobe in rats consist of two parts that are separately supplied by a portal vein each and a parenchymal transection plane can easily be created between the two using microsurgical techniques. The availability of small animal computer tomography (CT) and/or magnet resonance imaging (MRI) allows the very exact quantification of volumetric growth between portal vein ligation alone and portal vein ligation and the added transection, which is important for the validation of any rapid liver hypertrophy model.
The protocol presented here describes the surgical technique and procedures used for volumetric validation and physiological characterization of the model of slow and rapid hypertrophy after portal vein ligation and portal vein ligation with transection, respectively, in rats.

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			<td style="width:400px;">Attane, Piramal, Mumbai, India</td>
			<td style="width:255px;">LDNI 22098</td>
			<td style="width:340px;">Standard vet. equipment</td>
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			<td height="21" style="height:21px;">Tec-3 Isofluorane Vaporizer</td>
			<td>Ohmeda, GE-Healthcare, Chicago, IL</td>
			<td>not available anymore</td>
			<td>Standard vet. equipment&#160;</td>
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			<td height="21" style="height:21px;">Buprenorphine (Temgesic)</td>
			<td>Indivior, Baar, Switzerland</td>
			<td>7680419310353</td>
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			<td height="21" style="height:21px;">Microsurgery microscope</td>
			<td>Olympus, Tokio, Japan</td>
			<td>SZX10</td>
			<td>Standard vet. equipment</td>
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			<td>Mundipharma, Basel, Switzerland</td>
			<td>7680342821377</td>
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			<td>Carl Roth GmbH, Karlsruhe, Germany</td>
			<td>NK83.1</td>
			<td>Mini-sponges</td>
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			<td height="21" style="height:21px;">Abdominal Wall retractors</td>
			<td>N/A</td>
			<td>N/A</td>
			<td>Self-made from paper clips and Q-Tips</td>
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			<td height="21" style="height:21px;">3-0 silk&#160;</td>
			<td>Ethicon, Sommerville, NJ</td>
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			<td>World precision instruments (WPI), Sarasota, FL</td>
			<td>503371</td>
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			<td height="21" style="height:21px;">Adson forceps</td>
			<td>World precision instruments (WPI), Sarasota, FL</td>
			<td>501244-G</td>
			<td>Standard microsurgical</td>
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		<tr height="21">
			<td height="21" style="height:21px;">Fine tips microforceps</td>
			<td>World precision instruments (WPI), Sarasota, FL</td>
			<td>501976</td>
			<td>Tips need to be polished regularly</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Curved fine tips microforceps</td>
			<td>World precision instruments (WPI), Sarasota, FL</td>
			<td>504513</td>
			<td>Essential to go around the portal vein branches&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">6-0 LOOK black braided silk</td>
			<td>Surgical Specalities Corporation, Wyomissing, PA&#160;</td>
			<td>SP114</td>
			<td>Spool, precut prior to the procedure</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">2-0 silk sutures</td>
			<td>Ethicon, Sommerville, NJ</td>
			<td>K833</td>
			<td>Standard surgical</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">5-0 maxon sutures</td>
			<td>Covidien, Dublin, Ireland</td>
			<td>6608-21</td>
			<td>Standard surgical</td>
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		<tr height="21">
			<td height="21" style="height:21px;">Bipolar microforceps</td>
			<td>Sutter, Freiburg, Germany</td>
			<td>780148SGS</td>
			<td>Essential for parenchymal transection</td>
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		<tr height="21">
			<td height="21" style="height:21px;">Q-tips small</td>
			<td>Carl Roth GmbH, Karlsruhe, Germany</td>
			<td>EH11.1</td>
			<td>Standard surgical</td>
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			<td height="21" style="height:21px;">Q-tips big</td>
			<td>Carl Roth GmbH, Karlsruhe, Germany</td>
			<td>XL54.1</td>
			<td>Standard surgical</td>
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		<tr height="21">
			<td height="21" style="height:21px;">G30 needle&#160;</td>
			<td>Terumo, Tokyo, Japan</td>
			<td>NN-3013R&#160;</td>
			<td>Standard anesthesia equipment</td>
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		<tr height="21">
			<td height="21" style="height:21px;">2mm volume flow probe&#160;</td>
			<td>Transonic Systems, Ithaca, NY</td>
			<td>MA-2PS</td>
			<td>Smallest available probe for HAT-311 flow meter</td>
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		<tr height="21">
			<td height="21" style="height:21px;">Transonic flow meter</td>
			<td>Transonic Systems, Ithaca, NY</td>
			<td>HAT-311 Transsonic flow QC meter</td>
			<td>One of the&#160; first generation flow flow meters for surgery</td>
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		<tr height="21">
			<td height="21" style="height:21px;">ExiTron nano 12,000&#160;</td>
			<td>Miltenyi Biotech, Bergisch Gladbach, Germany</td>
			<td>130-095-698</td>
			<td>Nanomoloecular contrast medium that opacifies liver and spleen</td>
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		<tr height="21">
			<td height="21" style="height:21px;">G26 intravenous catheter</td>
			<td>Becton Dickinson, Franklin Lakes, NJ</td>
			<td>391349</td>
			<td>Standard anesthesia equipment</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Quantum FX MicroCT&#160;</td>
			<td>Perkin Elmer, Waltham, MA</td>
			<td>N/A</td>
			<td>Standard small animal CT scanner at the institute of physiology, University of Z&#252;rich</td>
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		<tr height="21">
			<td height="21" style="height:21px;">OsiriX 8.0</td>
			<td>Pixmeo Sarl, Geneva, Switzerland</td>
			<td>N/A</td>
			<td>Public domain software : www.pixmeo.com</td>
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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.

The two different surgical procedures portal vein ligation (PVL) and PVL with transection (PVL+T) result in distinctly different growth kinetics. PVL induces moderate volume increase within 3 days, whereas in PVL+T a much larger right median lobe (RML) can be seen (Figure 5). This can be verified by daily volumetry. The volume of the RML roughly doubles within 3 days in PVL, while it triples in PVL+T.17
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Watch this Scientific Journal Video about Rat Model of the Associating Liver Partition and Portal Vein Ligation for Staged Hepatectomy ALPPS Procedure at JoVE.com

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.

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 ...

rat-model-associating-liver-partition-portal-vein-ligation-for-staged

Research

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14.6K Views.  University of Zurich. 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. 

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

Cecal Ligation Puncture Procedure

Human sepsis is characterized by a set of systemic reactions in response to intensive and massive infection that failed to be locally contained by the host. Currently, sepsis ranks among the top ten causes of mortality in the USA intensive care units 1. During sepsis there are two established haemodynamic phases that may overlap. The initial phase (hyperdynamic) is defined as a massive production of proinflammatory cytokines and reactive oxygen species by macrophages and neutrophils that affects vascular permeability (leading to hypotension), cardiac function and induces metabolic changes culminating in tissue necrosis and organ failure. Consequently, the most common cause of mortality is acute kidney injury. The second phase (hypodynamic) is an anti-inflammatory process involving altered monocyte antigen presentation, decreased lymphocyte proliferation and function and increased apoptosis. This state known as immunosuppression or immune depression sharply increases the risk of nocosomial infections and ultimately, death. The mechanisms of these pathophysiological processes are not well characterized. Because both phases of sepsis may cause irreversible and irreparable damage, it is essential to determine the immunological and physiological status of the patient. This is the main reason why many therapeutic drugs have failed. The same drug given at different stages of sepsis may be therapeutic or otherwise harmful or have no effect 2,3. To understand sepsis at various levels it is crucial to have a suitable and comprehensive animal model that reproduces the clinical course of the disease. It is important to characterize the pathophysiological mechanisms occurring during sepsis and control the model conditions for testing potential therapeutic agents. 
To study the etiology of human sepsis researchers have developed different animal models. The most widely used clinical model is cecal ligation and puncture (CLP). The CLP model consists of the perforation of the cecum allowing the release of fecal material into the peritoneal cavity to generate an exacerbated immune response induced by polymicrobial infection. This model fulfills the human condition that is clinically relevant. As in humans, mice that undergo CLP with fluid resuscitation show the first (early) hyperdynamic phase that in time progresses to the second (late) hypodynamic phase. In addition, the cytokine profile is similar to that seen in human sepsis where there is increased lymphocyte apoptosis (reviewed in 4,5). Due to the multiple and overlapping mechanisms involved in sepsis, researchers need a suitable sepsis model of controlled severity in order to obtain consistent and reproducible results.

The mouse model of cecal ligation and puncture as a valuable tool for the study of human sepsis.

Human sepsis is characterized by a set of systemic reactions in response to intensive and massive infection that failed to be locally contained by the ...

3-Dimensional Resin Casting and Imaging of Mouse Portal Vein or Intrahepatic Bile Duct System

In organs, the correct architecture of vascular and ductal structures is indispensable for proper physiological function, and the formation and maintenance of these structures is a highly regulated process. The analysis of these complex, 3-dimensional structures has greatly depended on either 2-dimensional examination in section or on dye injection studies. These techniques, however, are not able to provide a complete and quantifiable representation of the ductal or vascular structures they are intended to elucidate. Alternatively, the nature of 3-dimensional plastic resin casts generates a permanent snapshot of the system and is a novel and widely useful technique for visualizing and quantifying 3-dimensional structures and networks.
A crucial advantage of the resin casting system is the ability to determine the intact and connected, or communicating, structure of a blood vessel or duct. The structure of vascular and ductal networks are crucial for organ function, and this technique has the potential to aid study of vascular and ductal networks in several ways. Resin casting may be used to analyze normal morphology and functional architecture of a luminal structure, identify developmental morphogenetic changes, and uncover morphological differences in tissue architecture between normal and disease states. Previous work has utilized resin casting to study, for example, architectural and functional defects within the mouse intrahepatic bile duct system that were not reflected in 2-dimensional analysis of the structure1,2, alterations in brain vasculature of a Alzheimer's disease mouse model3, portal vein abnormalities in portal hypertensive and cirrhotic mice4, developmental steps in rat lymphatic maturation between immature and adult lungs5, immediate microvascular changes in the rat liver, pancreas, and kidney in response in to chemical injury6.
Here we present a method of generating a 3-dimensional resin cast of a mouse vascular or ductal network, focusing specifically on the portal vein and intrahepatic bile duct. These casts can be visualized by clearing or macerating the tissue and can then be analyzed. This technique can be applied to virtually any vascular or ductal system and would be directly applicable to any study inquiring into the development, function, maintenance, or injury of a 3-dimensional ductal or vascular structure.

A method of visualizing and quantifying the 3-dimensional structure of mouse hepatic portal vein or intrahepatic bile duct is described. This resin cast technique can also be applied to other ductal or vascular systems and allows for in situ visualization or quantification of a system's intact communicating architecture.

In  organs, the correct architecture of vascular and ductal structures is  indispensable for proper physiological function, and the formation and  ...

Heterotopic Auxiliary Rat Liver Transplantation With Flow-regulated Portal Vein Arterialization in Acute Hepatic Failure

In acute hepatic failure auxiliary liver transplantation is an interesting alternative approach. The aim is to provide a temporary support until the failing native liver has regenerated.1-3 The APOLT-method, the orthotopic implantation of auxiliary segments- averts most of the technical problems. However this method necessitates extensive resections of both the native liver and the graft.4 In 1998, Erhard developed the heterotopic auxiliary liver transplantation (HALT) utilizing portal vein arterialization (PVA) (Figure 1). This technique showed promising initial clinical results.5-6 We developed a HALT-technique with flow-regulated PVA in the rat to examine the influence of flow-regulated PVA on graft morphology and function (Figure 2).
A liver graft reduced to 30 % of its original size, was heterotopically implanted in the right renal region of the recipient after explantation of the right kidney.&#160; The infra-hepatic caval vein of the graft was anastomosed with the infrahepatic caval vein of the recipient. The arterialization of the donor&#8217;s portal vein was carried out via the recipient&#8217;s right renal artery with the stent technique. The blood-flow regulation of the arterialized portal vein was achieved with the use of a stent with an internal diameter of 0.3 mm. The celiac trunk of the graft was end-to-side anastomosed with the recipient&#8217;s aorta and the bile duct was implanted into the duodenum. A subtotal resection of the native liver was performed to induce acute hepatic failure. 7
In this manner 112 transplantations were performed. The perioperative survival rate was 90% and the 6-week survival rate was 80%. Six weeks after operation, the native liver regenerated, showing an increase in weight from 2.3&#177;0.8 g to 9.8&#177;1 g. At this time, the graft&#8217;s weight decreased from 3.3&#177;0.8 g to 2.3&#177;0.8 g.
We were able to obtain promising long-term results in terms of graft morphology and function. HALT with flow-regulated PVA reliably bridges acute hepatic failure until the native liver regenerates.

Auxiliary liver transplantation provides a temporary support in acute hepatic failure, until regeneration of the failing liver. The heterotopic auxiliary liver transplantation (HALT) with portal vein arterialization (PVA) renders sufficient liver function. We developed an analogous technique in the rat, to examine the influence of the portal vein arterialization on the morphology and function of the graft.

In acute hepatic failure auxiliary liver transplantation is an interesting alternative approach. The aim is to provide a temporary support until the ...

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 ...

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 ...

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. ...

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 ...

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, ...

Repetitive Blood Sampling from the Subclavian Vein of Conscious Rat

Rats are widely used in pharmacokinetics (PK) and toxicokinetic (TK) studies that need to collect a certain amount of blood at specific time points to detect drug exposure. The rat blood sampling method determines the quality of the plasma and further affects the precision of the test results. The subclavian vein blood collection method described in this protocol collects blood samples repeatedly in the conscious state of animals to meet the needs of PK and TK tests. The skills of restraint handling and appropriate procedure of needle incision ensure the success rate of blood collection. It is easy to operate while ensuring the quality of plasma and at the same time catering to animal welfare. However, this method requires skilled operation, and an improper one may cause animal weakness, pain, lameness, and even mortality. The current method has been used in the testing facility for a 4-week oral toxicity study in Sprague Dawley (SD) rats with TK. The maximum amount of blood collected within 24 h did not exceed 20% of the animal's total blood. The animals' body weight was more than 200 g for males and females. The data showed that the animals' bodyweight increased steadily every week, and the clinical observation was normal after repetitive sample collection.

The present protocol describes a simple and efficient method for collecting blood from the subclavian vein in rats. It enables rapid, timely, and easily identifiable sampling without anesthesia and obtains high-quality blood through repetitive sample collection.

Rats are widely used in pharmacokinetics (PK) and toxicokinetic (TK) studies that need to collect a certain amount of blood at specific time points to ...

Robotic Taj Mahal Hepatectomy for Hilar Cholangiocarcinoma

Hilar cholangiocarcinoma is the most common malignant tumor of the biliary tract. Radical surgical resection is the only effective treatment option. In this study, a 32-year-old male patient with Bismuth Type IVa hilar cholangiocarcinoma underwent radical robotic resection of hepatic S4b, S5, and S1 (Taj Mahal hepatectomy) combined with regional lymphadenectomy, hilar bile duct reconstruction, and hepaticojejunostomy by the robotic surgical system. Postoperative pathological examination showed moderately-differentiated adenocarcinoma of the hilar bile duct. The surgical margins of the liver and bile ducts were negative. Recovery was smooth and the patient was discharged on the 17th postoperative day. The robotic surgical system and associated multiple instruments along with flexible and precise movements is suitable for the local hepatectomy around the porta hepatis, and delicate reconstruction of the hilar bile duct with a smaller diameter. This first clinical application study found that robotic Taj Mahal hepatectomy for hilar cholangiocarcinoma is safe and feasible and needs more experience for the evaluation of its long-term outcomes.

Robotic resection of hepatic S4b, S5, and S1 using the Taj Mahal procedure is feasible and safe for selected patients with hilar cholangiocarcinoma. The step-by-step details for this surgery are presented here.

Hilar cholangiocarcinoma is the most common malignant tumor of the biliary tract. Radical surgical resection is the only effective treatment option. In ...