This study was funded by the &#8220;Deutsche Forschungsgemeinschaft&#8221; (DFG). K. Schleimer was supported by the Lise Meitner Fellowship of the Ministry of Science and Research of NRW. We would like to thank Mrs. Mary-Joan Bl&#252;mich for her excellent editing assistance. Dr. Maria Kokozidou was financed from Fresenius 2011_A61.

1. Experimental Animals
<ol>
	<li>Obtain a Local Ethics Committee approval for all experiments which will be performed, in accordance with the animal protection FELASA guidelines (K 40, 17/99).</li>
	<li>Use male Lewis rats available to purchase from any commercial breeder (e.g., Charles River Wiga GmbH, Sulzfeld, Germany). Here, 224 animals (112 donors, 112 recipients) were used to perform 112 transplantations. The recipients were sacrificed at 6 weeks postoperatively. At the time of operation, the animals should weigh 250-350 g.</li>
	<li>Keep the animals in climate-controlled rooms with free access to food and water.</li>
</ol>
2. Anesthesia and Operative Preparation
<ol>
	<li>Place the rat in a plexiglas box connected to the anesthesia machine with an oxygen flow rate of 1 L/min, and an isofluorane vaporizer with 5 % anesthetic gas to induce anesthesia. Maintain anesthesia at 1.5 % isofluorane.</li>
	<li>Place the rats in supine position on a warming plate.</li>
	<li>Remove the fur of the abdomen with a depilation cream.</li>
	<li>Prepare a sterile surgical field as following: Use a disinfectant to clean the benchtop. For the disinfection of the incision site use Chlorhexidine first, alcohol second and, finally, a scrub solution (e.g., Chlorhexidine and 70% isopropyl alcohol). Wear a disposable surgical gown and surgical gloves.</li>
	<li>Use sterile microsurgery instruments.</li>
	<li>Use an operation microscope in 12-20-fold magnification.</li>
</ol>
3. Surgical Procedure
<ol>
	<li>Donor operation 
	 
	Preparation
	<ol>
		<li>Perform a median laparotomy and resect the left lateral lobe and the median lobe of the graft as described by Higgins.14</li>
		<li>Then prepare the hepatoduodenal ligament. First ligate the bile duct in order to induce congestion and dilation of the small bile duct. Then ligate and transect the gastroduodenal vein and artery. Afterwards, isolate the celiac trunk and the common hepatic artery and transect the left gastric artery and the splenic artery. Incise the congested bile duct, and introduce a 20-G stent into it. The positioning of the stent must ensure the drainage of the entire hilar bile duct system. Transect the bile duct distally to the stent.</li>
		<li>Isolate the infrahepatic segment of the caval vein right above the right renal vein. 
		 
		Perfusion</li>
		<li>After ligation of the aorta above the celiac trunk, clamp the portal vein and incise it. Introduce the perfusion catheter (14 G) into the portal vein, and perform the perfusion with 30 ml of histidine-tryptophan-ketoglutarate (HTK)-solution (12 cm H2O, 4&#176;C).</li>
		<li>Cut the diaphragm and the suprahepatic caval vein to allow the perfusate to flow out.</li>
		<li>Excise the celiac trunk along with an aortic patch and rinse it with histidine-tryptophan-ketoglutarate solution. 
		 
		Explantation</li>
		<li>Transect the infrahepatic caval vein right above the right renal vein.</li>
		<li>Then, place a stent with a diameter of 0.3 mm in the portal vein and fix it with a ligature. During the following operation, the portal vein is arterialized via the right renal artery. Transect the portal vein distally to the stent.</li>
		<li>After ligation of the suprahepatic caval vein, transect it together with a cuff of diaphragm.</li>
		<li>Explant the graft and store it in histidine-tryptophan-ketoglutarate (HTK)-solution at 4 &#176; Celsius in a plastic bag on ice. Place corner sutures (8-0 Ethilon) in the infrahepatic caval vein.</li>
	</ol>
	</li>
	<li>Recipient operation
	<ol>
		<li>Perform a median laparotomy and prepare the infrahepatic caval vein. Then isolate the right renal artery and the ureter, ligate the ureter and transect it. Clamp the right renal artery at its origin, then ligate the right renal vein. Then after transection of both renal vessels, perform the nephrectomy. Subsequently, shorten the right renal artery, rinse it with heparin saline solution (40 UI heparin/ml saline solution).</li>
		<li>Transect the right renal vein proximally to the ligature after proximal and distal clamping of the infrahepatic caval vein to create an oval lumen in the infrahepatic caval vein. Rinse the caval vein with heparin saline solution. Implant the graft in the right renal region of the recipient&#8217;s abdomen.</li>
		<li>Anastomose the donor&#8217;s infrahepatic caval vein end-to-side to the recipient`s caval vein with a 8-0 Ethilon running suture.</li>
		<li>After rinsing with heparin/saline solution, introduce the stent in the portal vein into the right renal artery (Figure 3). Connect the portal vein and renal artery with 2 stitches (8-0 Ethilon). Fix the linking stent in the renal artery with a ligature (braided silk black 7-0).</li>
		<li>To allow reperfusion, first remove the arterial clamp, then both venous clamps (Figure 4).</li>
		<li>Prepare the infrarenal aorta, then place a proximal and distal microclamp and incise the aorta right between both clamps. Perform an end-to-side anastomosis between the aorta and the donor&#8217;s celiac trunk, using an aortic patch, with a 10-0 Ethilon running suture.</li>
		<li>Insert the bile duct into the duodenum: Apply a pursestring suture in the duodenal wall, make a small incision in the duodenal wall right in the middle of the pursestring. Introduce the stented bile duct into the duodenum, and tighten the pursestring suture. Finally, hold the duodenum and the bile duct tightly together with two stitches (Ethilon 8-0) (Figure 5).</li>
		<li>Then perform a subtotal resection of the native liver, first described by Emond et al. to mimic acute hepatic failure.7</li>
		<li>Fix the suprahepatic caval vein of the graft, together with a cuff of diaphragm, to the lateral abdominal wall of the recipient with 4-0 Vicryl suture. Rinse the abdomen with saline solution (Figure 6).</li>
		<li>For the muscular layer use a 4-0 Vicryl running suture and for the cutaneous a 3-0 Vicryl running suture.</li>
	</ol>
	</li>
</ol>
4. Recovery and Postoperative Management
<ol>
	<li>Let the animals recover from anesthesia under an infrared warming lamp.</li>
	<li>Inject Buprenorphine at a dose of 0.03-0.05 mg/kg B.W. sc every 8-12 hr&#160;for 2 days.</li>
	<li>Examine the animals concerning the general condition and signs of illness or infections.</li>
</ol>
5. Calculation of the Initial Native Liver Weight
Calculate the initial native liver weight in the following manner: subtract the weight of the resected liver lobes from the complete liver weight (2.66% of body weight (this value with a standard deviation of +/- 0.49% was determined in previous experiments with n=80 animals of the same strain and age)).15

<ol>
	<li>Boudjema, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Auxiliary+liver+transplantation+for+fulminant+and+subfulminant+hepatic+failure.">Auxiliary liver transplantation for fulminant and subfulminant hepatic failure.</a> Transplantation. 59, 218-223 (1995).</li><li>Boudjema, K., Jaeck, D., Sim&#233;oni, U., Bientz, J., Chenard, M. P., Brunot, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Temporary+auxiliary+liver+transplantation+for+subacute+liver+failure+in+a+child.">Temporary auxiliary liver transplantation for subacute liver failure in a child.</a> The Lancet. 342, 778-779 (1993).</li><li>Chenard-Neu, M. 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=Auxiliary+liver+transplantation:+Regeneration+of+the+native+liver+and+outcome+in+30+patients+with+fulminant+hepatic+failure+-+a+multicenter+European+study.">Auxiliary liver transplantation: Regeneration of the native liver and outcome in 30 patients with fulminant hepatic failure - a multicenter European study.</a> Hepatology. 23, 1119-1127 (1996).</li><li>Gubernatis, G., Pichlmayr, R., Kemnitz, J., Gratz, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Auxiliary+partial+orthotopic+liver&#8211;transplantation+(APOLT)+for+fulminant+hepatic+failure:+first+successful+case+report.">Auxiliary partial orthotopic liver&#8211;transplantation (APOLT) for fulminant hepatic failure: first successful case report.</a> World J Surg. 15, 660-666 (1991).</li><li>Erhard, J., Lange, R., Giebler, R., Rauen, U., de Groot, H., Eigler, F. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Arterialization+of+the+portal+vein+in+orthotopic+and+auxiliary+liver+transplantation.">Arterialization of the portal vein in orthotopic and auxiliary liver transplantation.</a> Transplantation. 60, 877-879 (1995).</li><li>Erhard, 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=Auxiliary+liver+transplantation+with+arterialization+of+the+portal+vein+for+acute+hepatic+failure.">Auxiliary liver transplantation with arterialization of the portal vein for acute hepatic failure.</a> Transpl Int. 11, 266-271 (1998).</li><li>Emond, J., Capron-Laudereau, M., Meriggi, F., Bernuau, J., Reynes, M., Houssin, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extent+of+Hepatectomy+in+the+rat.">Extent of Hepatectomy in the rat.</a> Eur Surg Res. 21, 251-259 (1989).</li><li>Mas, A., Rode`s, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fulminant+hepatic+failure.">Fulminant hepatic failure.</a> Lancet. 349, 1081-1085 (1997).</li><li>Terpstra, O. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Auxiliary+liver+grafting:+a+new+concept+in+liver+transplantation.">Auxiliary liver grafting: a new concept in liver transplantation.</a> The Lancet. 342, 758 (1993).</li><li>Terpstra, O. T., Reuvers, C. B., Schalm, S. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Auxiliary+heterotopic+liver+transplantation.">Auxiliary heterotopic liver transplantation.</a> Transplantation. 45, 1003-1007 (1988).</li><li>Schleimer, K., Lange, R., Rauen, U., Erhard, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Auxiliary+liver+transplantation+in+acute+liver+failure+in+the+rat+-+an+illustrated+description+of+a+new+surgical+approach.">Auxiliary liver transplantation in acute liver failure in the rat - an illustrated description of a new surgical approach.</a> Langenbecks Arch Surg. 384 (2), 204-208 (1999).</li><li>Schleimer, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Physiologic+microcirculation+of+the+heterotopically+transplanted+rat+liver+with+portal+vein+arterialization+depending+on+optimal+stent+diameter.">Physiologic microcirculation of the heterotopically transplanted rat liver with portal vein arterialization depending on optimal stent diameter.</a> Med Sci Monit. 28 (BR140-145), (2006).</li><li>Hong, H. Q., 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=Study+of+portal+arterialization+with+auxiliary+liver+in+rats.">Study of portal arterialization with auxiliary liver in rats.</a> Hiroshima J. Med. Sci. 40, 29-33 (1991).</li><li>Higgins, G. M., Anderson, 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=Experimental+pathology+of+the+liver.+I--Restoration+of+the+liver+of+the+white+rat+following+partial+surgical+removal.">Experimental pathology of the liver. I--Restoration of the liver of the white rat following partial surgical removal.</a> Arch. Path. 12, 186-202 (1931).</li><li>Schleimer, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Auxiliary+liver+transplantation+with+flow-regulated+portal+vein+arterialization+offers+a+successful+therapeutic+option+in+acute+hepatic+failure--investigations+in+heterotopic+auxiliary+rat+liver+transplantation.">Auxiliary liver transplantation with flow-regulated portal vein arterialization offers a successful therapeutic option in acute hepatic failure--investigations in heterotopic auxiliary rat liver transplantation.</a> Transpl Int. 19 (7), 581-588 (2006).</li><li>Lee, S., Edgington, T. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Liver+transplantation+in+the+rat.">Liver transplantation in the rat.</a> Surg. Forum. 17, 220-222 (1966).</li><li>Hess, F., Willemen, A., Jerusalem, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Auxiliary+liver+transplantation+in+the+rat,+influence+of+the+condition+of+the+recipient's+liver+on+the+fate+of+the+graft.">Auxiliary liver transplantation in the rat, influence of the condition of the recipient's liver on the fate of the graft.</a> Eur. Surg. Res. 9, 270-279 (1977).</li><li>Aguirrezabalaga, J., Arnal, F., Marini, M., Centeno, A., Fernandez-Selles, C., Rey, I., Gomez, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Auxiliary+liver+transplantation+with+portal+arterialization+in+the+rat:+description+of+a+new+model.">Auxiliary liver transplantation with portal arterialization in the rat: description of a new model.</a> Microsurgery. 22, 21-26 (2002).</li><li>Palmes, D., Dietl, K. H., Drews, G., Holzen, J. P., Spiegel, H. U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Auxiliary+partial+orthotopic+liver+transplantation:+treatment+of+acute+liver+failure+in+a+new+rat+model.">Auxiliary partial orthotopic liver transplantation: treatment of acute liver failure in a new rat model.</a> Langenbecks Arch Surg. (386), 534-541 (2002).</li><li>Schleimer, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improved+microcirculation+of+a+liver+graft+by+controlled+portal+vein+arterialization.">Improved microcirculation of a liver graft by controlled portal vein arterialization.</a> J Surg Res. 116 (2), 202-210 (2004).</li><li>Schleimer, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Portal+hyperperfusion+causes+disturbance+of+microcirculation+and+increased+rate+of+hepatocellular+apoptosis:+investigations+in+heterotopic+rat+liver+transplantation+with+portal+vein+arterialization.">Portal hyperperfusion causes disturbance of microcirculation and increased rate of hepatocellular apoptosis: investigations in heterotopic rat liver transplantation with portal vein arterialization.</a> Transplant Proc. 38 (3), 725-729 (2006).</li></ol>

All authors declared no competing interests.

The first heterotopic auxiliary rat liver transplantation was described by Lee et al.,16 in 1966 followed by Hess.17 The portal vein of the graft was anastomosed with the portal vein of the recipient. During this procedure, the portal venous blood supply to the native liver is compromised.
In 1991 Hong performed HALT with PVA via the iliac artery of the recipient.13 Without blood flow regulation massive portal and sinusoid congestions occurred.
<p ...

Acute hepatic failure poses a severe problem in clinical medicine leading to a mortality rate of 60-80 %.8 In acute hepatic failure, auxiliary liver transplantation is a promising alternative therapy to bridge the acute phase. The native liver is left to regenerate and following to the regeneration the immunosuppression drugs can be discontinued. As a consequence the graft will become atrophic. However the operative technique for auxiliary liver transplantation is still discussed.1-3 In this context, Terpstra reported the lack of space for the graft, the portal blood steal phenomenon and the problem of venous congestion and drainage.9-10 The donor&#8217;s portal vein was anastomosed end-to-side to the recipient&#8217;s portal vein. This resulted in portal flow competition between the graft and the native liver and in portal vein thrombosis. Most of those technical problems can be avoided with the use of the APOLT-method (orthotopic implantation of auxiliary segments).4 However this method necessitates extensive resections of both the native liver and the graft.4 In 1998, Erhard and his team developed the heterotopic auxiliary liver transplantation (HALT) utilizing portal vein arterialization (PVA) (Figure 1). The hilum and the portal vein of the native liver are respected with the use of this method. That spares the recipient from unwanted side-effects such as portal vein thrombosis and portal blood steal phenomenon, which could disturb native liver recovery. Additionally, no extensive liver resections of the native liver and graft are required for this method, with consequently less bleeding and more remaining total liver parenchymal mass for bridging (graft) and regeneration (native liver). This technique showed promising initial clinical results.5-6 The goal of this experimental work was the development of a HALT technique with portal vein arterialization in the rat for research purposes (Figure 2). In the preliminary experiments we didn&#8217;t take into consideration the blood flow regulation of the arterialized portal vein, which resulted in congestion of the transplanted graft after reperfusion and massive bleeding from the liver capsule.11&#160; Since then the blood flow in the arterialized portal vein was regulated by a stent with an inner diameter of 0.3 mm and a length of 8 mm. Pilot experiments had shown that a stent diameter of 0.3 mm yields an average blood flow in the arterialized portal vein that is within the upper physiological range (1.7 +/- 0.4 ml/min/g liver weight).12&#160; Our results without blood flow regulation correlate with the results of Hong, who performed HALT with PVA via the iliac artery of the recipient.13 In his experiments without blood flow regulation massive portal and sinusoid congestions occurred.
The aim of our video is to demonstrate step by step this ne.w experimental surgical technique in the rat. In the long term the proposed technique can be used in studies on liver regeneration and inter-liver competition and portal vein arterialization, portal vein hyperperfusion and portal blood flow regulation.

<table border="0" cellpadding="0" cellspacing="0" width="573">
	<tbody>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">Braided Silk black 7-0&#160;</td>
			<td style="width:71px;">Ethicon Products</td>
			<td style="width:119px;">892100</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">Vicryl 3-0</td>
			<td style="width:71px;">Ethicon Products</td>
			<td style="width:119px;">J285G</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">Vicryl 4-0</td>
			<td style="width:71px;">Ethicon Products</td>
			<td style="width:119px;">J284G</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">Ethilon 8-0</td>
			<td style="width:71px;">Ethicon Products</td>
			<td style="width:119px;">1714G</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">Ethilon 10-0</td>
			<td style="width:71px;">Ethicon Products</td>
			<td style="width:119px;">7770G</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Vasofix safety 14G</td>
			<td style="width:71px;">B Braun</td>
			<td style="width:119px;">2758853</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Vasofix safety 20G</td>
			<td style="width:71px;">B Braun</td>
			<td style="width:119px;">2758818</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="201">
			<td height="201" style="height:201px;width:216px;">2 French (.012&#8221;/0.3mm ID x .025&#8221;/0.6mm OD) x 24&#8221;/60cm polyurethane catheter</td>
			<td style="width:71px;">Access technologies a division of Norfolk Medical, Inc., Illinois, USA</td>
			<td style="width:119px;">CNC-2P</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="119">
			<td height="119" style="height:119px;width:216px;">HTK solution,</td>
			<td rowspan="2" style="width:71px;">Dr. Franz K&#246;hler Chemie GmbH, Alsbach-H&#228;hnlein, Germany</td>
			<td rowspan="2" style="width:119px;"></td>
			<td rowspan="2" style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Custodiol</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:216px;">Isofluorane 5 %</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Any genericon</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:216px;">Heparin</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Any genericon</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:216px;">0.9% saline</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Any genericon</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:216px;">Buprenorphine</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Any genericon</td>
		</tr>
	</tbody>
</table>

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.

The mean duration of the transplantation was about 150 min. The cold ischemia time was 64 +/- 7 min, the warm ischemia time was less than 25 min.
The perioperative survival rate was 90% and the 6-week survival rate was 80%. The 20 % loss was due to peritonitis because of stent dislocation and biliary leakage (four animals) during the first postoperative week and due to pneumonia, intra-abdominal abscess and ileus (seven animals) during the following five weeks. The surviving animals were in ex...

Watch this Scientific Journal Video about Heterotopic Auxiliary Rat Liver Transplantation With Flow-regulated Portal Vein Arterialization in Acute Hepatic Failure at JoVE.com

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

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 ...

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12.6K Views.  University Hospital RWTH Aachen. 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.

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

Orthotopic Liver Transplantation in Rats

Clinical progress in the field of liver transplantation has been largely supported by animal models1,2. Since the publication of the first orthotopic rat liver transplantation in 1979 by Kamada et al.3, this model has remained the gold standard despite various proposed alternative techniques4. Nevertheless, its broader use is limited by its steep learning curve5.
In this video paper, we show a simple and easy-to-establish revision of Kamada's two-cuff technique. The suprahepatic vena cava anastomosis is performed manually with a running suture, and the vena porta and infrahepatic vena cava anastomoses are performed utilizing a quick-linker cuff system6. Manufacturing the quick-linker kit is shown in a separate video paper.

We present an easy-to-establish revision of the classical two-cuff technique for orthotopic liver transplantation in rat.

Clinical progress in the field of liver transplantation has been largely supported by animal models1,2. Since the publication of the first orthotopic rat ...

Surgical Procedures for a Rat Model of Partial Orthotopic Liver Transplantation with Hepatic Arterial Reconstruction

Orthotopic liver transplantation (OLT) in rats using a whole or partial graft is an indispensable experimental model for transplantation research, such as studies on graft preservation and ischemia-reperfusion injury 1,2, immunological responses 3,4, hemodynamics 5,6, and small-for-size syndrome 7. The rat OLT is among the most difficult animal models in experimental surgery and demands advanced microsurgical skills that take a long time to learn. Consequently, the use of this model has been limited. Since the reliability and reproducibility of results are key components of the experiments in which such complex animal models are used, it is essential for surgeons who are involved in rat OLT to be trained in well-standardized and sophisticated procedures for this model.
While various techniques and modifications of OLT in rats have been reported 8 since the first model was described by Lee et al. 9 in 1973, the elimination of the hepatic arterial reconstruction 10 and the introduction of the cuff anastomosis technique by Kamada et al. 11 were a major advancement in this model, because they simplified the reconstruction procedures to a great degree. In the model by Kamada et al., the hepatic rearterialization was also eliminated. Since rats could survive without hepatic arterial flow after liver transplantation, there was considerable controversy over the value of hepatic arterialization. However, the physiological superiority of the arterialized model has been increasingly acknowledged, especially in terms of preserving the bile duct system 8,12 and the liver integrity 8,13,14.
In this article, we present detailed surgical procedures for a rat model of OLT with hepatic arterial reconstruction using a 50% partial graft after ex vivo liver resection. The reconstruction procedures for each vessel and the bile duct are performed by the following methods: a 7-0 polypropylene continuous suture for the supra- and infrahepatic vena cava; a cuff technique for the portal vein; and a stent technique for the hepatic artery and the bile duct.

Orthotopic liver transplantation in rats is an indispensable experimental model for biomedical research. Here we present our surgical procedures for orthotopic rat liver transplantation with hepatic arterial reconstruction using a 50% partial graft.

Orthotopic liver transplantation (OLT) in rats using a whole or partial graft is an indispensable experimental model for transplantation research, such as ...

Rat Heterotopic Abdominal Heart/Single-lung Transplantation in a Volume-loaded Configuration

Herein, we describe a novel technique for heterotopic abdominal heart-lung transplantation (HAHLT) in rats. The configuration of the transplant graft involves anastomosis of donor inferior vena cava (IVC) to recipient IVC, and donor ascending aorta (Ao) to recipient abdominal Ao. The right upper and middle lung lobes are preserved and function as conduits for blood flow from right heart to left heart.
There are several advantages to using this technique, and it lends itself to a broad range of applications. Because the graft is transplanted in a configuration that allows for dyamic volume-loading, cardiac function may be directly assessed in vivo. The use of pressure-volume conductance catheters permits characterization of load-dependent and load-independent hemodynamic parameters. The graft may be converted to a loaded configuration by applying a clamp to the recipient&#8217;s infra-hepatic IVC. We describe modified surgical techniques for both donor and recipient operations, and an ideal myocardial protection strategy. Depending on the experimental aim, this model may be adapted for use in both acute and chronic studies of graft function, immunologic status, and variable ventricular loading conditions. The conducting airways to the transplanted lung are preserved, and allow for acute lung re-ventilation. This facilitates analysis of the effects of the mixed venous and arterial blood providing coronary perfusion to the graft.
A limitation of this model is its technical complexity. There is a significant learning curve for new operators, who should ideally be mentored in the technique. A surgical training background is advantageous for those wishing to apply this model. Despite its complexity, we aim to present the model in a clear and easily applicable format. Because of the physiologic similarity of this model to orthotopic transplantation, and its broad range of study applications, the effort invested in learning the technique is likely to be worthwhile.

We describe a novel technique for heterotopic abdominal heart-lung transplantation (HAHLT) in rats. The transplant configuration results in a partially loaded graft circulation, allowing direct functional assessment. This model may be employed for acute or chronic studies of function and immunologic status of the transplanted graft.

Herein, we describe a novel technique for heterotopic abdominal heart-lung transplantation (HAHLT) in rats. The configuration of the transplant graft ...

Heterotopic Cervical Heart Transplantation in Mice

The heterotopic cervical heart transplantation in mice is a valuable tool in transplant and cardiovascular research. The cuff technique greatly simplifies this model by avoiding challenging suture anastomoses of small vessels thereby reducing warm ischemia time. In comparison to abdominal graft implantation the cervical model is less invasive and the implanted graft is easily accessible for further follow-up examinations. Anastomoses are performed by pulling the ascending aorta of the graft over the cuff with the recipient&#8217;s common carotid artery and by pulling the main pulmonary artery over the cuff with the external jugular vein. Selection of appropriate cuff size and complete mobilization of the vessels are important for successful revascularization. Ischemia-reperfusion (I/R) injury can be minimized by perfusing the graft with a cardioplegic solution and by hypothermia. In this article, we provide technical details for a simplified and improved cuff technique, which should allow surgeons with basic microsurgical skills to perform the procedure with a high success rate.

The cuff technique shortens and facilitates the model of heterotopic cervical heart transplantation in mice by avoiding technically challenging suture anastomoses of small vessels. The technical details shown in this video paper should allow researches to establish this model in their laboratories.

The heterotopic cervical heart transplantation in mice is a valuable tool in transplant and cardiovascular research. The cuff technique greatly simplifies ...

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Invasive Hemodynamic Characterization of the Portal-hypertensive Syndrome in Cirrhotic Rats

This is a detailed protocol describing invasive hemodynamic measurements in cirrhotic rats for the characterization of portal hypertensive syndrome. Portal hypertension (PHT) due to cirrhosis is responsible for the most severe complications in patients with liver disease. The full picture of the portal hypertensive syndrome is characterized by increased portal pressure (PP) due to the increased intrahepatic vascular resistance (IHVR), hyperdynamic circulation, and increased splanchnic blood flow. Progressive splanchnic arterial vasodilation and increased cardiac output with elevated heart rate (HR) but low arterial pressure characterizes the portal hypertensive syndrome.
Novel therapies are currently being developed that aim to decrease PP by either targeting IHVR or increased splanchnic blood flow &#8212; but side effects on systemic hemodynamics may occur. Thus, a detailed characterization of portal venous, splanchnic, and systemic hemodynamic parameters, including measurement of PP, portal venous blood flow (PVBF), mesenteric arterial blood flow, mean arterial pressure (MAP), and HR is needed for preclinical evaluation of the efficacy of novel treatments for PHT. Our video article provides the reader with a structured protocol for performing invasive hemodynamic measurements in cirrhotic rats. In particular, we describe the catheterization of the femoral artery and the portal vein via an ileocolic vein and the measurement of portal venous and splanchnic blood flow via perivascular Doppler-ultrasound flow probes. Representative results of different rat models of PHT are shown.

Here we describe a detailed protocol for invasive measurements of hemodynamic parameters including portal pressure, splanchnic blood flow, and systemic hemodynamics in order to characterize the portal hypertensive syndrome in rats.

This is a detailed protocol describing invasive hemodynamic measurements in cirrhotic rats for the characterization of portal hypertensive syndrome. ...

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 ...

Reduced Complications after Arterial Reconnection in a Rat Model of Orthotopic Liver Transplantation

The rat orthotopic liver transplantation (OLT) model is a powerful tool to study acute and chronic rejection. However, it is not a complete representation of human liver transplantation due to the absence of arterial reconnection. Described here is a modified transplantation procedure that includes the incorporation of hepatic artery (HA) reconnection, leading to a marked improvement in transplant outcomes. With a mean anhepatic time of 12 min and 14 s, HA reconnection results in improved perfusion of the transplanted liver and an increase in long-term recipient survival from 37.5% to 88.2%. This protocol includes the use of 3D-printed cuffs and holders to connect the portal vein and infrahepatic inferior vena cava. It can be implemented for studying multiple aspects of liver transplantation, from immune response and infection to technical aspects of the procedure. By incorporating a simple and practical method for arterial reconnection using a microvascular technique, this modified rat OLT protocol closely mimics aspects of human liver transplantation and will serve as a valuable and clinically relevant research model.

The goal of this study is to modify the rat orthotopic liver transplant model to better represent human liver transplantation and improve recipient survival. The presented method reestablishes hepatic arterial inflow by connecting the donor liver&#39;s common hepatic artery to the recipient liver&#39;s proper hepatic artery.

The rat orthotopic liver transplantation (OLT) model is a powerful tool to study acute and chronic rejection. However, it is not a complete representation ...