This work was supported by grants from the SNF [31003A-138528], the Octav and the Marcella Botnar Foundation, the Novartis Foundation and the Emma Muschamp Foundation. We thank Martine Lambelet, and&#160;Jean-Christophe Stehle for their excellent technical assistance.

The Ethical Committee of the University of Lausanne approved the experiments, which are in accordance with the principles outlined in the Declaration of Helsinki of 1975, as revised in 1983 for the use of human tissues.
1. Human Great Saphenous Vein Harvest
<ol>
	<li>Obtain surplus segments of non-varicose human saphenous veins from patients undergoing lower limb bypass surgery for ischemia. In the operating room, disinfect the entire leg with an iodine solution and drape the patient to expose the leg from the groin to the foot.</li>
	<li>Make a median incision from the groin to the knee (leaving the interrupted skin portion).</li>
	<li>Harvest the great saphenous vein with a pedicle of surrounding tissue (no-touch technique). Secure side branches of the veins with 4-0 silk ties. Immediately store a minimum of 9 cm long surplus segment of the greater saphenous vein, with an external diameter of 2.5-4 mm at 4 &#176;C in a RPMI-1640 Glutamax medium, supplemented with 12.5% fetal calf serum and bring it to the laboratory.</li>
</ol>
2. EVPS Design
<ol>
	<li>Assemble the general equipment shown in Figure 1. Autoclave all equipment and keep all components under sterile conditions. In addition, ensure that the system is waterproof and does not leak chemicals into the medium. Use polymethacrylate methyl (PMMA-GS) for the cover. Steel (X5 Cr Ni 18 10) and polyoxymethylene plastic (POM) as the vein support.</li>
	<li>Design the perfusion chamber to the desired geometry to allow the placement of the vein and its connection. Make sure the depth (or radius if using cylindrical construction) is at least 2.5 cm so it allows minimal flexion and dilatation of the vessel along with constant coverage by the culture media (Figure 1). Sealing is a major issue and is the reason rectangular PMMA-GS construction is used.</li>
	<li>Design the vein support to the desired geometry. To avoid vein kinking or over distension, allow length adjustment by pushing or pulling (screw cannot be used to that purpose, as the vein would be twisted along with the screw). 
	NOTE: A full steel rod connected by 2 sliding L-shaped pieces that support the 2 vein cylinders (5 mm diameter to fit the vessel) and the vein (Figure 1B and Figure 2) is used here.</li>
	<li>Design the pressure column, such that the &#8220;resting pressure&#8221; applied to the system is: p = 0-10 = h x &#961; x g, where p = pressure (N/m2, Pa) h = height of fluid column (m) &#961; = density of liquid (kg/m3) and g = the gravitational constant (9.81 m/sec2). Design four connection ducts, from top to bottom: to apply pressure, for the outflow (from the vein), the inflow (to the vein) and to allow medium change.</li>
	<li>Prepare the medium. Based on previous studies5,11-14, choose RPMI-1640, supplemented with Glutamax, 12.5% fetal calf serum, and 1% antibiotic-antimycotic solution (10,000 U/ml penicillin G, plus 10 mg/ml streptomycin sulfate, plus 25 mg/ml amphotericin B, plus 0.5 &#956;g/ml: gentamycin). Shear stress (SS) is given by SS= 4 &#956;Q/&#960;*r3Q is the flow rate (ml/sec), r the radius (cm) of the vein segment, and &#956; is the viscosity of the perfusion medium.
	<ol>
		<li>Modulate SS by adjusting the viscosity through addition of 70 kDa dextran. Measure the viscosity with a viscometer. Here, add 8% 70 kDa dextran to set SS to 9-15 dyn/cm2.</li>
	</ol>
	</li>
	<li>Set the gearing pump to induce a pulsatile cardioid signal of 60 pulses/min and constant amplitude generating a unidirectional flow of 150 &#177; 15 ml/min, independent from the pressure applied in the system and controlled by a computer. Ensure that the driving software integrates constant acquisition and monitoring of pressures, flow velocity, pulse rate, and signal. If desired, use a second pump (non synchronized) to produce a non-laminar, turbulent flow.</li>
</ol>
3. EVPS Assembly (Figure 1)
<ol>
	<li>Before starting, make sure all the equipment is sterile. Perform all the following steps under asepsis in a laminar flow hood.</li>
	<li>Place the vein in a Petri dish filled with medium. Use a surgical blade and divide the vein into 3 equal segments.</li>
	<li>Immediately rinse one segment in PBS. Divide the segment in 3 parts, fix one in formalin for morphometry. Freeze the other two for quantitative transcript (RT-PCR) and protein (western blot) analysis. Consider these segments as a control, non-perfused vein.</li>
	<li>Use the 2 remaining segments for perfusion.
	<ol>
		<li>Very gently inject medium into the vein and determine the normal flow direction; in presence of valves the vein is reversed.</li>
		<li>Sealing the veins is of utmost importance to experimental success. Check for leaks through collaterals. Secure any leaks with 6-0 silk sutures.</li>
	</ol>
	</li>
	<li>Connect the vein segment between the two metallic cylinders, one end at a time (2.3, Figure 1). Secure the cylinders with Ethibon 3-0 around the indentations (Figure 1A and B).
	<ol>
		<li>Place the entire venous segment into the perfusion chamber previously filled with medium. Repeat the same procedure for the second segment. 
		NOTE: Failure to properly seal the vein to the cylinder will be a source of leak, require reintervention, and significantly increase the risk of infection and experimental failure.</li>
	</ol>
	</li>
	<li>To reinforce (mesh) the second segment, release the two cylinders (with the vein attached) from the L-shaped pieces (2.3 and Figure 1).
	<ol>
		<li>Be gentle and do not touch the vein with any instruments. Slide the mesh first on the cylinder then onto the vein. A push/pull jostling will get the mesh on the vein.</li>
		<li>Once the mesh covers the entire surface of the vein secure the jacketed vein to the cylinders with Ethibon 3-0.</li>
		<li>Reassemble the vein/cylinder compound to the L-shaped support and transfer it to the perfusion chamber, previously filled with medium.</li>
	</ol>
	</li>
	<li>Connect each metallic cylinder (in-and outflow) to a Y-splitter using peroxide-treated silicone tubing with an internal diameter of 3.2 mm.</li>
	<li>Connect the outflow splitter to a second Y-splitter using the same type of tubing. From this Y-splitter, use one tube to measure the perfusion pressure through both vessels. Connect the other one back to the column to form a closed loop system (Figure 2).</li>
	<li>Inside the incubator, use a long (one-meter length) tube to connect the pressure column to the pump head.</li>
	<li>Complete the set up by connecting the pump head to the inflow Y-splitter with another long length tube (Figure 1).</li>
</ol>
4. Veins Perfusion
<ol>
	<li>After the EVPS assembly has been completed, fill the column with medium (stay below the vein outflow duct to allow refilling). Add more medium into the column until the system is full. Move all the system into the incubator maintained at 37 &#177; 0.1 &#176;C with a pH kept constant at 7.40 &#177; 0.01 (using a CO2/pH algorithm based on the Henderson-Hasselbach equation).</li>
	<li>Bring the gear pump head outside the incubator and connect it to the gear pump drive. Screw the rods to secure the assembly.</li>
	<li>Switch on the pump power, make sure it is activated on the driving software and allow 5 min for the medium to be equally distributed in every compartment.</li>
	<li>To monitor the pressure, use an arterial line monitoring. Connect the EVPS pressure output (it corresponds to the arterial catheter) to the pressure transducer linked to the computer.
	<ol>
		<li>Make sure the tube is entirely filled with medium and does not contain any bubbles. De-bubble the culture system through the &#8220;arterial line&#8221; tube (Figure 2). Pay attention to the display and look for a pulsatile cardioid signal of 60 pulses/min of constant amplitude. At this point, the average pressure is between 0-10 mm Hg. If the pressure is &#60; 0 and the column progressively empties look for a leak (vein collateral or inadequate seal between the vein and the tube).</li>
	</ol>
	</li>
	<li>Set the minimal pressure to 6 mm Hg for a venous test or at 90 mm Hg for an arterial test. Under these conditions, an air injector applies the required pressure to the column and system.</li>
	<li>Change the medium every 2 days by using the tube connected to the pressure column. To prevent pressure change damage, open the column plug first.</li>
</ol>
5. Completion of the Perfusion
<ol>
	<li>After 3 or 7 days of perfusion: take the EVPS out of the incubator and dismount the veins. Discard the 5 mm proximal and distal vein ends attached to the equipment. Cut a central, 5 mm thick rings from the remaining segment and fix in formalin (morphometry). Freeze the remaining fragments and reduce into powder for further molecular analyses.</li>
</ol>

<ol>
	<li>Sal Go, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Executive+summary:+heart+disease+and+stroke+statistics--2014+update:+a+report+from+the+american+heart+association.">Executive summary: heart disease and stroke statistics--2014 update: a report from the american heart association.</a> Circulation. 129, 399-410 (2014).</li><li>Sal Conte, 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=Results+of+PREVENT+III:+a+multicenter,+randomized+trial+of+edifoligide+for+the+prevention+of+vein+graft+failure+in+lower+extremity+bypass+surgery.">Results of PREVENT III: a multicenter, randomized trial of edifoligide for the prevention of vein graft failure in lower extremity bypass surgery.</a> Journal of Vascular Surgery. 43, 742-751 (2006).</li><li>Yu, P., Nguyen, B. T., Tao, M., Bai, Y., Ozaki, C. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mouse+vein+graft+hemodynamic+manipulations+to+enhance+experimental+utility.">Mouse vein graft hemodynamic manipulations to enhance experimental utility.</a> The American Journal of Pathology. 178, 2910-2919 (2011).</li><li>Davies, M. G., Hagen, P. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reprinted+article+&amp;#34;Pathophysiology+of+vein+graft+failure:+a+review&amp;#34;.">Reprinted article &amp;#34;Pathophysiology of vein graft failure: a review&amp;#34;.</a> European journal of vascular and endovascular surgery : the official journal of the European Society for Vascular Surgery. 42, S19-S29 (2011).</li><li>Berard, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+hemodynamic+forces+in+the+ex+vivo+arterialization+of+human+saphenous+veins.">Role of hemodynamic forces in the ex vivo arterialization of human saphenous veins.</a> Journal of Vascular Surgery. 57, 1371-1382 (2013).</li><li>Vijayan, V., 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=Long-term+reduction+of+medial+and+intimal+thickening+in+porcine+saphenous+vein+grafts+with+a+polyglactin+biodegradable+external+sheath.">Long-term reduction of medial and intimal thickening in porcine saphenous vein grafts with a polyglactin biodegradable external sheath.</a> Journal of Vascular Surgery. 40, 1011-1019 (2004).</li><li>Jeremy, J. Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On+the+biology+of+saphenous+vein+grafts+fitted+with+external+synthetic+sheaths+and+stents.">On the biology of saphenous vein grafts fitted with external synthetic sheaths and stents.</a> Biomaterials. 28, 895-908 (2007).</li><li>Zilla, 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=Constrictive+external+nitinol+meshes+inhibit+vein+graft+intimal+hyperplasia+in+nonhuman+primates.">Constrictive external nitinol meshes inhibit vein graft intimal hyperplasia in nonhuman primates.</a> The Journal of Thoracic and Cardiovascular Surgery. 136, 717-725 (2008).</li><li>Zilla, 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=Utilization+of+shape+memory+in+external+vein-graft+meshes+allows+extreme+diameter+constriction+for+suppressing+intimal+hyperplasia:+a+non-human+primate+study.">Utilization of shape memory in external vein-graft meshes allows extreme diameter constriction for suppressing intimal hyperplasia: a non-human primate study.</a> Journal of Vascular Surgery. 49, 1532-1542 (2009).</li><li>Yeoman, M. 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=A+constitutive+model+for+the+warp-weft+coupled+non-linear+behavior+of+knitted+biomedical+textiles.">A constitutive model for the warp-weft coupled non-linear behavior of knitted biomedical textiles.</a> Biomaterials. 31, 8484-8493 (2010).</li><li>Longchamp, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+use+of+external+mesh+reinforcement+to+reduce+intimal+hyperplasia+and+preserve+the+structure+of+human+saphenous+veins.">The use of external mesh reinforcement to reduce intimal hyperplasia and preserve the structure of human saphenous veins.</a> Biomaterials. 35, 2588-2599 (2014).</li><li>Saucy, F., 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=Ex+vivo+pulsatile+perfusion+of+human+saphenous+veins+induces+intimal+hyperplasia+and+increased+levels+of+the+plasminogen+activator+inhibitor+1.">Ex vivo pulsatile perfusion of human saphenous veins induces intimal hyperplasia and increased levels of the plasminogen activator inhibitor 1.</a> European Surgical Research. Europaische Chirurgische Forschung. Recherches Chirurgicales Europeennes. 45, 50-59 (2010).</li><li>Dubuis, 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=Atorvastatin-loaded+hydrogel+affects+the+smooth+muscle+cells+of+human+veins.">Atorvastatin-loaded hydrogel affects the smooth muscle cells of human veins.</a> The Journal of pharmacology and experimental. 347, 574-581 (2013).</li><li>Deglise, 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=Increased+connexin43+expression+in+human+saphenous+veins+in+culture+is+associated+with+intimal+hyperplasia.">Increased connexin43 expression in human saphenous veins in culture is associated with intimal hyperplasia.</a> Journal of Vascular Surgery. 41, 1043-1052 (2005).</li><li>Muto, A., Model, L., Ziegler, K., Eghbalieh, S. D., Dardik, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanisms+of+vein+graft+adaptation+to+the+arterial+circulation:+insights+into+the+neointimal+algorithm+and+management+strategies.">Mechanisms of vein graft adaptation to the arterial circulation: insights into the neointimal algorithm and management strategies.</a> Circulation Journal : Official Journal of the Japanese Circulation Society. 74, 1501-1512 (2010).</li><li>Tao, 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=A+simplified+murine+intimal+hyperplasia+model+founded+on+a+focal+carotid+stenosis.">A simplified murine intimal hyperplasia model founded on a focal carotid stenosis.</a> The American Journal of Pathology. 182, 277-287 (2013).</li><li>Berard, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Salvage+treatment+for+venous+aneurysm+complicating+vascular+access+arteriovenous+fistula:+use+of+an+exoprosthesis+to+reinforce+the+vein+after+aneurysmorrhaphy.">Salvage treatment for venous aneurysm complicating vascular access arteriovenous fistula: use of an exoprosthesis to reinforce the vein after aneurysmorrhaphy.</a> European Journal of Vascular and Endovascular Surgery : the Official Journal of the European Society for Vascular Surgery. 40, 100-106 (2010).</li></ol>

The authors have nothing to disclose.

This study uncovers an ex&#160;vivo vein perfusion system (EVPS) to perform extensive hemodynamic studies in human veins. This system allows saphenous veins perfusion under defined hemodynamic parameters in the absence of aggravating inflammatory and growth factors released by circulating cells in vivo. Thus, it provides a better understanding of the underlying pathways involved in the control of IH in human veins grafts5,11,12,15.
Reproducible and quantifiable hemodynamic perturbations are limited in vivo. Several complex murine microsurgical procedures have been described. Using a bypass isograft model via interposition of a vena cava from a donor mouse into the right common carotid artery and the additional creation of an outflow branch ligation, mid graft or common carotid stenosis, flow and SS acutely decreased and enhanced IH3. Outward versus inward remodeling can further be interrogated using a mid-focal versus distal common carotid stenosis16. In large animals (sheep, pig, and baboon), bypass grafts are technically easier and represent an attractive approach to test pre-clinical human sized devices such as the mesh used in the present study8-10. However, its cost and the paucity of validated molecular tools limit the use of these strategies. Finally, these flow manipulations constantly alter wall tension and fail to interrogate one single constituent. In addition, the intricate relationships between the hemodynamics and the immune and endocrine systems further limit the analysis of a single actor.
Several issues arise with the use of the EVPS. 1) Low-grade bacterial contamination often accompanied human vein harvest and the ex-vivo absence of circulating cells stand as an important cause of infection. This is mainly prevented by hand washing the pieces separately then autoclaving all material prior to use. Furthermore the assembly is performed in less than 90 minutes and under rigorous asepsis. 2) Sealing that endures repeated sterilization. For this reason, a rectangular PMMA-GS construction was used, avoiding the use of joints and limiting deformation. 3) SS and wall tension are calculated at defined time points, based on the vessel lumen radius (histology), the flow and viscosity being constant. The integration of a longitudinal imaging (high definition camera, laser or Doppler) that continuously monitors the vein diameter and/or flow will provide more detailed information on local flow variations and allow cyclic strain calculations. 4) The two parallel vein segments may have uncontrolled differences in their wall compliance and radius. Thus, we only compare segments from a same vein and assume that under the same pressure, the flow rate pattern is similar in both segments.
In this study, veins were submitted to pulsatile laminar flow; however, 50% of intimal hyperplastic lesions occur in the end-to-side perianastomotic areas of the vein graft, where laminar flow is disrupted. Turbulent conditions can be modeled with the addition of a second pump, non-synchronized with the first pump. Future studies will be performed to specifically assess the impact of laminar flow disruption on IH and the potentially beneficial effect of mesh reinforcement. Interestingly, the flexible structure of the mesh allows circumferential wrapping at the anastomosis sites, as already performed to repair aneurysmal fistulas17 (Figure 4). Thus, the mesh could prove useful to limit perianastomotic dilatation, laminar flow disruption and consequently reduce IH at the anastomosis sites. This may be particularly beneficial in distal bypass graft, frequently affected by diameter mismatch between the vein and the tibial or peroneal artery.
In summary, the setup shown here allows parallel perfusion of human veins, under identical hemodynamic conditions. These data demonstrate that the use of an external macroporous tubular polyester mesh is an efficient method to limit the development of IH in vein grafts inserted into an arterial environment11. This system can profit several areas of research. Especially, it emerges as a powerful tool to perform pre-clinical studies testing the feasibility and efficiency of various approaches to reduce IH in human material, and is a valuable addition to in vivo animal models. Other prosthetic supports or meshes coated with pharmaceutical agents will be evaluated using this method6-10. In addition, one could envision to test locally applied pharmacological molecules to prevent IH in human tissue, under near physiological state. Gene therapy interventions are also achievable, transducing a vein segment to overexpress or silence target genes of interest.
In conclusion, our system will increase our understanding of the hemodynamic contribution to human vein graft diseases. It provides an innovative platform to test new therapeutic strategies and may arise as a &#8220;bench to beside translation tool.&#8221;

Cardiovascular diseases are the leading cause of morbidity and mortality in Western countries1. Despite advances made in endovascular treatments, bypass surgery remains the mainstay of contemporary therapies, thus over half a million vein grafts are performed annually in the United States. However, despite decades of research, 30-60% of lower extremity vein grafts fail within the first years due to intimal hyperplasia (IH)2. Mechanical forces, particularly low shear stress (SS) and high wall tension, are pivotal in the initiation and development of this hyperplastic response3,4. To address this issue, an ex&#160;vivo veins perfusion system (EVPS) was generated to study, under strictly controlled hemodynamic conditions (pressure and shear stress), the behavior of human saphenous veins. In this study, following insertion into the arterial-like circulation, high pressure (mean = 100 mm Hg) was sufficient to stimulate proliferation and migration of smooth muscle cells into the intimal layer (IH)5.
Mammalian studies have suggested the use of external reinforcement as an efficient method to support the &#8220;arterialized vein&#8221; and counteract the acute hemodynamic changes the vein faces once implanted into an arterial milieu. The mesh prevented over-distension, increased shear stress, and reduced wall tension and consequently IH6-10. However, the underlying mechanisms and its applicability to human veins in improving bypass patency have not been fully characterized. Our EVPS was used to compare, in condition mimicking the alterations a vein faces once inserted into an arterial regimen (high shear stress and pressure), the behavior of human saphenous veins in the absence and presence of an external macroporous polyester tubular mesh. By preventing pathological remodeling and IH, the mesh provided evidence of its potential clinical efficiency11.
This study 1) introduces a model of ex&#160;vivo human saphenous veins perfusion under controlled pressure and shear stress 2) demonstrates that external macro-porous polyester mesh reduces IH and provides crucial information for its potential clinical application.

<table border="0" cellpadding="0" cellspacing="0" width="1113">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:453px;">Name</td>
			<td style="width:371px;">Company</td>
			<td style="width:145px;">Catalog Number</td>
			<td style="width:144px;">Comments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">RPMI 1640 - Glutamax</td>
			<td>Life Technologies</td>
			<td>61870-010</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;"><a name="RANGE!A3">Penicilline/Streptomycine/Fungizone</a></td>
			<td>Bioconcept</td>
			<td>4-02F00-H</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dextran from Leuconostoc spp. 500 gr.</td>
			<td>Sigma-Aldrich</td>
			<td>31390</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tampon PBS CHUV pH 7.1-7.3 1 lt.</td>
			<td>Laboratorium und Grosse Apotheke Dr. G. Bichsel AG</td>
			<td>100 0 324 00</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cryosectionning embedding medium - Tissue-Tek OCT Compound</td>
			<td>Fisher Scientific</td>
			<td>14-373-65</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Silicon Tubing (Peroxide) L/S 16 (96400-16 ) - 7.5m</td>
			<td>Idex Health &#38; Science GMBH</td>
			<td>MF0037ST</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Y-splitter&#160;</td>
			<td>Idex Health &#38; Science GMBH</td>
			<td>Y-connector</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">35 mm Culture dish</td>
			<td>Sigma-Aldrich</td>
			<td>CLS430165-100EA</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">15 ml Falcon tube</td>
			<td>BD Bioscence</td>
			<td>352096</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">50 ml Falcon tube</td>
			<td>BD Bioscence</td>
			<td>352098</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Gearing pump - Reglo-Z</td>
			<td>Idex Health &#38; Science GMBH</td>
			<td>SM 895&#160;</td>
			<td>&#160;App-Nr 03736-00194</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Pump Head</td>
			<td>Idex Health &#38; Science GMBH</td>
			<td>MI0008&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Monitoring Kit TRANSPAC IV</td>
			<td>icumedical</td>
			<td>011-0J736-01</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">20 mL Syringes</td>
			<td>B. Braun Medical SA</td>
			<td>4612041-02</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Etibon 3-0 FS-2</td>
			<td>Ethicon- Johnson&#38;Johnson</td>
			<td>EH7346H</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mesh ProVena 6-8mm</td>
			<td>B. Braun Medical SA</td>
			<td>1105012-14</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">NaCl: Sodium Chlorure Solution perfusion 0.9% (100 ml)</td>
			<td>B. Braun Medical SA</td>
			<td>534534</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Masterflex L/S Standard Drive</td>
			<td>Cole-Parmer Instrument Co</td>
			<td>7521-10</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Acquisition card</td>
			<td>National Instruments</td>
			<td>PCI-6024 E</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Flowmeter module</td>
			<td>Transonic Systems Inc.</td>
			<td>TS410 and T402</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Stopcock with 3-ways</td>
			<td>BD Connexta Luerlock</td>
			<td>394600</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Millex Filter</td>
			<td>Milian</td>
			<td>SE2M229I04</td>
			<td></td>
		</tr>
	</tbody>
</table>

procedure for human saphenous veins ex vivo perfusion and external reinforcement

The mainstay of contemporary therapies for extensive occlusive arterial disease is venous bypass graft. However, its durability is threatened by intimal hyperplasia (IH) that eventually leads to vessel occlusion and graft failure. Mechanical forces, particularly low shear stress and high wall tension, are thought to initiate and to sustain these cellular and molecular changes, but their exact contribution remains to be unraveled. To selectively evaluate the role of pressure and shear stress on the biology of IH, an ex&#160;vivo perfusion system (EVPS) was created to perfuse segments of human saphenous veins under arterial regimen (high shear stress and high pressure). Further technical innovations allowed the simultaneous perfusion of two segments from the same vein, one reinforced with an external mesh. Veins were harvested using a no-touch technique and immediately transferred to the laboratory for assembly in the EVPS. One segment of the freshly isolated vein was not perfused (control, day 0). The two others segments were perfused for up to 7 days, one being completely sheltered with a 4 mm (diameter) external mesh. The pressure, flow velocity, and pulse rate were continuously monitored and adjusted to mimic the hemodynamic conditions prevailing in the femoral artery. Upon completion of the perfusion, veins were dismounted and used for histological and molecular analysis. Under ex&#160;vivo conditions, high pressure perfusion (arterial, mean = 100 mm Hg) is sufficient to generate IH and remodeling of human veins. These alterations are reduced in the presence of an external polyester mesh.

The EVPS provides a valuable tool to independently assess the hemodynamic forces on human saphenous vein grafts remodeling and IH.
Figure 1 shows the perfusion chamber and the vein support. In Figures 1A and B, the vein support before (Figure 1A) and after (Figure 1B) assembly, respectively, is pictured. It is composed (from the top to the bottom) of 1 plain stainless steel tube measuring 9 cm, which serves as a support for 2 L-shaped pieces that can easily slide (from the left to the right) and provides a reliable technique to adjust the support size to the vein. Each of these pieces holds a POM disc to fit a steel cylinder (vein connector) fixed in place by integrated screw (arrowhead). Figure 1C-D shows the perfusion chamber alone (C) and after insertion of the vein support (D). On the perfusion chamber, depressions are designed to hold the vein support in place (top) and to avoid kinking of the connecting tube coming in and out from the vein (bottom).
Figure 2 shows real time pictures (Figure 2A) and a schematic representation (Figure 2B) of the EVPS. The perfusion chamber, veins and its supports, as well as the pressure column, are maintained in a controlled environment (temperature, CO2 and O2) whereas the pump, pressure injector, and control devices all remain outside the incubator. The figure illustrates the gearing pump (1) that generates a pulsatile signal controlled by a computer (2), which monitors the flow velocity (3), pressure (4), and controls the minimal diastolic pressure (5); two segments of a same saphenous vein are connected in parallel to the perfusion pump inside separate perfusion chambers (6a and 6b) placed in a cell culture incubator.
In Figure 3, histomorphometric analysis shows that external reinforcement prevents intimal hyperplasia and pathological media remodeling otherwise observed after 7 days under high pressure (arterial regimen, mean = 100 mm Hg) perfusion. In Figure 3A, representative histological sections stained for Hematoxylin-eosin (HE) reveals the lining of the lumen by nuclei of endothelial cells and the nuclei of SMCs in the media layer in all conditions. Figures 3B-C shows representative Van Gieson Elastic Lamina (VGEL) stained sections. In Figure 3B, the intima is thickened (IH) in veins perfused at high pressure (mean = 100 mm Hg) for 7 days compared to control non-perfused veins, a phenomenon largely decreased in the presence of an external mesh. Figure 3C illustrates the pathological outward remodeling and media thinning in veins subjected to 7 days of arterial pressure. This is largely prevented by the external reinforcement. Furthermore, in Figure 3D, Masson&#8217;s trichrome staining (blue=connective tissue, red=muscle) associates this pathological remodeling with the persistence of only one of the three muscle layers and accumulation of smooth muscle cells in the inner layer (intima). The external reinforcement preserves the distribution of the SMCs and media structure.
Figure 4 illustrates a current clinical application of the external mesh. An illustrative example is provided by external reinforcement of an aneurysmal arterio-venous fistula (hemodialysis access). Figure 4A shows a time-course representation of the vein reinforcement (from the top to the bottom). First, the mesh was placed around a rigid tube while the vein&#8217;s extremity is fixed to a mandrel (upper panel). Then, the vein was pulled through the tube thanks to the mandrel. Once the vein was in place, the tube was slowly retracted, leaving the mesh around the vein (upper and middle panel). In this particular case, the procedure was repeated on both sides of the veins, and the veins segments and mesh reinforcements were assembled by an end-to-end anastomosis (lower panel). Figure 4B provides a larger view of the arterio-venous end-to-side anastomosis, showing that the mesh is wrapped around the anastomosis by tying it along the posterior wall of the artery.
<img alt="Figure 1" fo:content-width="5in" src="/files/ftp_upload/52079/52079fig1highres.jpg" width="500" /> 
Figure 1.&#160;The vein support and perfusion chamber. A. The vein support is composed of 1 plain tube, 2 L-shaped pieces, discs and cylinders (form the top to the bottom). B. The vein support once assembled. C. View of the perfusion chamber. D. The perfusion chamber is designed to hold in place the vein support and allows its connection to the vein and connecting tubes.
<img alt="Figure 2" fo:content-width="5in" src="/files/ftp_upload/52079/52079fig2highres.jpg" width="500" /> 
Figure 2.&#160;The ex&#160;vivo perfusion system. A. The completely assemble EVPS in the cell-culture incubator. B. Schematic representation. 1) the pump generating a pulsatile cardioid wave; 2) the computer controlling the pressure, flow (type, rate and amplitude); 3) the flow meter; 4) the pressure transducer &#8211; arterial line; 5) the pressure injector; 6) two segments of a very same saphenous vein are perfused without (6a) or with external mesh reinforcement (6b).
<img alt="Figure 3" fo:content-width="5in" src="/files/ftp_upload/52079/52079fig3highres.jpg" width="500" /> 
Figure 3.&#160;The external reinforcement prevents intimal hyperplasia. A. Representative histological sections stained with Hematoxylin-eosin (HE). Bar represents 50 &#181;m. B-C. Representative histological sections stained for elastin (VGEL). l = lumen m = media, IH = intimal hyperplasia. Bar represents 50 &#181;m. D. Representative histological sections stained with Masson&#8217;s trichrome. Bar represents 50 &#181;m.
<img alt="Figure 4" fo:content-width="5in" src="/files/ftp_upload/52079/52079fig4highres.jpg" width="500" /> 
Figure 4.&#160;External reinforcement of an aneurysmal fistula. A. Time-course photographs of vein reinforcement (from top to bottom). B. Larger view of the arterio-venous end-to-side anastomosis.

Watch this Scientific Journal Video about Procedure for Human Saphenous Veins Ex Vivo Perfusion and External Reinforcement at JoVE.com

Procedure for Human Saphenous Veins Ex Vivo Perfusion and External Reinforcement

The mechanisms leading to the development of intimal hyperplasia (IH) and vein graft failure are still poorly understood. This study describes an ex&#160;vivo system to perfuse human veins under controlled flow and pressure. Furthermore the efficiency of external mesh reinforcement to limit the development of IH was evaluated.

Procedure for Human Saphenous Veins Ex Vivo Perfusion and External Reinforcement

The mainstay of contemporary therapies for extensive occlusive arterial disease is venous bypass graft. However, its durability is threatened by intimal ...

procedure-for-human-saphenous-veins-ex-vivo-perfusion-external

Universidad San Sebastian

Research

JoVE Journal

Medicine

11.1K Views.  Brigham and Women's Hospital/Harvard Medical School. The mechanisms leading to the development of intimal hyperplasia (IH) and vein graft failure are still poorly understood. This study describes an ex vivo system to perfuse human veins under controlled flow and pressure. Furthermore the efficiency of external mesh reinforcement to limit the development of IH was evaluated.

Video: Procedure for Human Saphenous Veins Ex Vivo Perfusion and External Reinforcement

Technique of Subnormothermic Ex Vivo Liver Perfusion for the Storage, Assessment, and Repair of Marginal Liver Grafts

The success of liver transplantation has resulted in a dramatic organ shortage. In most transplant regions 20-30% of patients on the waiting list for liver transplantation die without receiving an organ transplant or are delisted for disease progression. One strategy to increase the donor pool is the utilization of marginal grafts, such as fatty livers, grafts from older donors, or donation after cardiac death (DCD). The current preservation technique of cold static storage is only poorly tolerated by marginal livers resulting in significant organ damage. In addition, cold static organ storage does not allow graft assessment or repair prior to transplantation.
These shortcomings of cold static preservation have triggered an interest in warm perfused organ preservation to reduce cold ischemic injury, assess liver grafts during preservation, and explore the opportunity to repair marginal livers prior to transplantation. The optimal pressure and flow conditions, perfusion temperature, composition of the perfusion solution and the need for an oxygen carrier has been controversial in the past.
In spite of promising results in several animal studies, the complexity and the costs have prevented a broader clinical application so far. Recently, with enhanced technology and a better understanding of liver physiology during ex vivo perfusion the outcome of warm liver perfusion has improved and consistently good results can be achieved.
This paper will provide information about liver retrieval, storage techniques, and isolated liver perfusion in pigs. We will illustrate a) the requirements to ensure sufficient oxygen supply to the organ, b) technical considerations about the perfusion machine and the perfusion solution, and c) biochemical aspects of isolated organs.

Technique of Subnormothermic Ex Vivo Liver Perfusion for the Storage, Assessment, and Repair of Marginal Liver Grafts

Marginal grafts, such as fatty livers, grafts from older donors, or livers retrieved after cardiac death (DCD) tolerate conventional, cold static storage only poorly. We developed a novel model of subnormothermic ex vivo liver perfusion for preservation, assessment, and repair of marginal liver grafts prior to transplantation.

The success of liver transplantation has resulted in a dramatic organ shortage. In most transplant regions 20-30% of patients on the waiting list for ...

Method of Isolated Ex Vivo Lung Perfusion in a Rat Model: Lessons Learned from Developing a Rat EVLP Program

The number of acceptable donor lungs available for lung transplantation is severely limited due to poor quality. Ex-Vivo Lung Perfusion (EVLP) has allowed lung transplantation in humans to become more readily available by enabling the ability to assess organs and expand the donor pool. As this technology expands and improves, the ability to potentially evaluate and improve the quality of substandard lungs prior to transplant is a critical need. In order to more rigorously evaluate these approaches, a reproducible animal model needs to be established that would allow for testing of improved techniques and management of the donated lungs as well as to the lung-transplant recipient. In addition, an EVLP animal model of associated pathologies, e.g., ventilation induced lung injury (VILI), would provide a novel method to evaluate treatments for these pathologies. Here, we describe the development of a rat EVLP lung program and refinements to this method that allow for a reproducible model for future expansion. We also describe the application of this EVLP system to model VILI in rat lungs. The goal is to provide the research community with key information and &#8220;pearls of wisdom&#8221;/techniques that arose from trial and error and are critical to establishing an EVLP system that is robust and reproducible.

Method of Isolated Ex Vivo Lung Perfusion in a Rat Model: Lessons Learned from Developing a Rat EVLP Program

Ex-Vivo Lung Perfusion (EVLP) has allowed lung transplantation in humans to become more readily available by enabling the ability to assess organs and expand the donor pool. Here, we describe the development of a rat EVLP program and refinements that allow for a reproducible model for future expansion.

The number of acceptable donor lungs available for lung transplantation is severely limited due to poor quality. Ex-Vivo Lung Perfusion (EVLP) has allowed ...

An Ex vivo Model to Study Hormone Action in the Human Breast

The study of hormone action in the human breast has been hampered by lack of adequate model systems. Upon in vitro culture, primary mammary epithelial cells tend to lose hormone receptor expression. Widely used hormone receptor positive breast cancer cell lines are of limited relevance to the in vivo situation. Here, we describe an ex vivo model to study hormone action in the human breast. Fresh human breast tissue specimens from surgical discard material such as reduction mammoplasties or mammectomies are mechanically and enzymatically digested to obtain tissue fragments containing ducts and lobules and multiple stromal cell types. These tissue microstructures kept in basal medium without growth factors preserve their intercellular contacts, the tissue architecture, and remain hormone responsive for several days. They are readily processed for RNA and protein extraction, histological analysis or stored in freezing medium. Fluorescence activated cell sorting (FACS) can be used to enrich for specific cell populations. This protocol provides a straightforward, standard approach for translational studies with highly complex, varied human specimens.

An Ex vivo Model to Study Hormone Action in the Human Breast

We have developed a novel ex vivo model to study hormone action in the human breast. It is based on tissue microstructures isolated from surgical breast tissue specimens which preserve tissue architecture, intercellular interactions, and paracrine signaling.

The study of hormone action in the human breast has been hampered by lack of adequate model systems. Upon in vitro culture, primary mammary epithelial ...

Human Dupuytren's Ex Vivo Culture for the Study of Myofibroblasts and Extracellular Matrix Interactions

Organ fibrosis or &#8220;scarring&#8221; is known to account for a high death toll due to the extensive amount of disorders and organs affected (from cirrhosis to cardiovascular diseases). There is no effective treatment and the in vitro tools available do not mimic the in vivo situation rendering the progress of the out of control wound healing process still enigmatic.
To date, 2D and 3D cultures of fibroblasts derived from DD patients are the main experimental models available. Primary cell cultures have many limitations; the fibroblasts derived from DD are altered by the culture conditions, lack cellular context and interactions, which are crucial for the development of fibrosis and weakly represent the derived tissue. Real-time PCR analysis of fibroblasts derived from control and DD samples show that little difference is detectable. 3D cultures of fibroblasts include addition of extracellular matrix that alters the native conditions of these cells. 
As a way to characterize the fibrotic, proliferative properties of these resection specimens we have developed a 3D culture system, using intact human resections of the nodule part of the cord. The system is based on transwell plates with an attached nitrocellulose membrane that allows contact of the tissue with the medium but not with the plastic, thus, preventing the alteration of the tissue. No collagen gel or other extracellular matrix protein substrate is required. The tissue resection specimens maintain their viability and proliferative properties for 7 days. This is the first &#8220;organ&#8221; culture system that allows human resection specimens from DD patients to be grown ex vivo and functionally tested, recapitulating the in vivo situation.

Human Dupuytren's Ex Vivo Culture for the Study of Myofibroblasts and Extracellular Matrix Interactions

Dupuytren&#8217;s disease (DD) is a fibroproliferative disease of the palm of the hand. Here, we present a protocol to culture resection specimens from DD in a three-dimensional (3D) culture system. Such short-term culture system allows preservation of the 3D structure and molecular properties of the fibrotic tissue.

Organ fibrosis or &#8220;scarring&#8221; is known to account for a high death toll due to the extensive amount of disorders and organs affected (from ...

Ex Situ Normothermic Machine Perfusion of Donor Livers

In contrast to conventional static cold preservation (0-4 &#176;C), ex situ machine perfusion may provide better preservation of donor livers. Continuous perfusion of organs provides the opportunity to improve organ quality and allows ex situ viability assessment of donor livers prior to transplantation. This video article provides a step by step protocol for ex situ normothermic machine perfusion (37 &#176;C) of human donor livers using a device that provides a pressure and temperature controlled pulsatile perfusion of the hepatic artery and continuous perfusion of the portal vein. The perfusion fluid is oxygenated by two hollow fiber membrane oxygenators and the temperature can be regulated between 10 &#176;C and 37 &#176;C. During perfusion, the metabolic activity of the liver as well as the degree of injury can be assessed by biochemical analysis of samples taken from the perfusion fluid. Machine perfusion is a very promising tool to increase the number of livers that are suitable for transplantation.

Ex Situ Normothermic Machine Perfusion of Donor Livers

Here we present a protocol describing oxygenated ex situ machine perfusion of donor liver grafts. This article contains a step by step protocol to procure and prepare the liver graft for machine perfusion, prepare the perfusion fluid, prime the perfusion machine and perform oxygenated normothermic machine perfusion of the liver graft.

In contrast to conventional static cold preservation (0-4 &#176;C), ex situ machine perfusion may provide better preservation of donor livers. Continuous ...

Normothermic Ex Vivo Kidney Perfusion for the Preservation of Kidney Grafts prior to Transplantation

Kidney transplantation has become a well-established treatment option for patients with end-stage renal failure. The persisting organ shortage remains a serious problem. Therefore, the acceptance criteria for organ donors have been extended leading to the usage of marginal kidney grafts. These marginal organs tolerate cold storage poorly resulting in increased preservation injury and higher rates of delayed graft function. To overcome the limitations of cold storage, extensive research is focused on alternative normothermic preservation methods.
Ex vivo normothermic organ perfusion is an innovative preservation technique. The first experimental and clinical trials for ex vivo lung, liver, and kidney perfusions demonstrated favorable outcomes.
In addition to the reduction of cold ischemic injury, the method of normothermic kidney storage offers the opportunity for organ assessment and repair. This manuscript provides information about kidney retrieval, organ preservation techniques, and isolated ex vivo normothermic kidney perfusion (NEVKP) in a porcine model. Surgical techniques, set up for the perfusion solution and the circuit, potential assessment options, and representative results are demonstrated.

Normothermic Ex Vivo Kidney Perfusion for the Preservation of Kidney Grafts prior to Transplantation

The severe organ shortage has resulted in increased use of marginal kidney grafts for transplantation. This has triggered interest in alternative storage methods, since marginal grafts especially tolerate cold storage poorly. The technique of normothermic ex vivo kidney perfusion (NEVKP) represents a novel preservation method for kidney grafts prior to &#160;transplantation.

Kidney transplantation has become a well-established treatment option for patients with end-stage renal failure. The persisting organ shortage remains a ...

Generation of Microtumors Using 3D Human Biogel Culture System and Patient-derived Glioblastoma Cells for Kinomic Profiling and Drug Response Testing

The use of patient-derived xenografts for modeling cancers has provided important insight into cancer biology and drug responsiveness. However, they are time consuming, expensive, and labor intensive. To overcome these obstacles, many research groups have turned to spheroid cultures of cancer cells. While useful, tumor spheroids or aggregates do not replicate cell-matrix interactions as found in vivo. As such, three-dimensional (3D) culture approaches utilizing an extracellular matrix scaffold provide a more realistic model system for investigation. Starting from subcutaneous or intracranial xenografts, tumor tissue is dissociated into a single cell suspension akin to cancer stem cell neurospheres. These cells are then embedded into a human-derived extracellular matrix, 3D human biogel, to generate a large number of microtumors. Interestingly, microtumors can be cultured for about a month with high viability and can be used for drug response testing using standard cytotoxicity assays such as 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and live cell imaging using Calcein-AM. Moreover, they can be analyzed via immunohistochemistry or harvested for molecular profiling, such as array-based high-throughput kinomic profiling, which is detailed here as well. 3D microtumors, thus, represent a versatile high-throughput model system that can more closely replicate in vivo tumor biology than traditional approaches.

Patient-derived xenografts of glioblastoma multiforme can be miniaturized into living microtumors using 3D human biogel culture system. This in vivo-like 3D tumor assay is suitable for drug response testing and molecular profiling, including kinomic analysis.

The use of patient-derived xenografts for modeling cancers has provided important insight into cancer biology and drug responsiveness. However, they are ...

A Small Animal Model of Ex Vivo Normothermic Liver Perfusion

There is a significant shortage of liver allografts available for transplantation, and in response the donor criteria have been expanded. As a result, normothermic ex vivo liver perfusion (NEVLP) has been introduced as a method to evaluate and modify organ function. NEVLP has many advantages in comparison to hypothermic and subnormothermic perfusion including reduced preservation injury, restoration of normal organ function under physiologic conditions, assessment of organ performance, and as a platform for organ repair, remodeling, and modification. Both murine and porcine NEVLP models have been described. We demonstrate a rat model of NEVLP and use this model to show one of its important applications &#8212; the use of a therapeutic molecule added to liver perfusate. Catalase is an endogenous reactive oxygen species (ROS) scavenger and has been demonstrated to decrease ischemia-reperfusion in the eye, brain, and lung. Pegylation has been shown to target catalase to the endothelium. Here, we added pegylated-catalase (PEG-CAT) to the base perfusate and demonstrated its ability to mitigate liver preservation injury. An advantage of our rodent NEVLP model is that it is inexpensive in comparison to larger animal models. A limitation of this study is that it does not currently include post-perfusion liver transplantation. Therefore, prediction of the function of the organ post-transplantation cannot be made with certainty. However, the rat liver transplant model is well established and certainly could be used in conjunction with this model. In conclusion, we have demonstrated an inexpensive, simple, easily replicable NEVLP model using rats. Applications of this model can include testing novel perfusates and perfusate additives, testing software designed for organ evaluation, and experiments designed to repair organs.

A Small Animal Model of Ex Vivo Normothermic Liver Perfusion

There is a significant liver donor shortage, and criteria for liver donors have been expanded. Normothermic ex vivo liver perfusion (NEVLP) has been developed to evaluate and modify organ function. This study demonstrates a rat model of NEVLP and tests the ability of pegylated-catalase, to mitigate liver preservation injury.

There is a significant shortage of liver allografts available for transplantation, and in response the donor criteria have been expanded. As a result, ...

Optocardiography and Electrophysiology Studies of Ex Vivo Langendorff-perfused Hearts

Small animal models are most commonly used in cardiovascular research due to the availability of genetically modified species and lower cost compared to larger animals. Yet, larger mammals are better suited for translational research questions related to normal cardiac physiology, pathophysiology, and preclinical testing of therapeutic agents. To overcome the technical barriers associated with employing a larger animal model in cardiac research, we describe an approach to measure physiological parameters in an isolated, Langendorff-perfused piglet heart. This approach combines two powerful experimental tools to evaluate the state of the heart: electrophysiology (EP) study and simultaneous optical mapping of transmembrane voltage and intracellular calcium using parameter sensitive dyes (RH237, Rhod2-AM). The described methodologies are well suited for translational studies investigating the cardiac conduction system, alterations in action potential morphology, calcium handling, excitation-contraction coupling and the incidence of cardiac alternans or arrhythmias.

The objective of this study was to establish a method for investigating cardiac dynamics using a translational animal model. The described experimental approach incorporates dual-emission optocardiography in conjunction with an electrophysiological study to assess electrical activity in an isolated, intact porcine heart model.

Small animal models are most commonly used in cardiovascular research due to the availability of genetically modified species and lower cost compared to ...

Determining and Controlling External Power Output During Regular Handrim Wheelchair Propulsion

The use of a manual wheelchair is critical to 1% of the world&#39;s population. Human powered wheeled mobility research has considerably matured, which has led to improved research techniques becoming available over the last decades. To increase the understanding of wheeled mobility performance, monitoring, training, skill acquisition, and optimization of the wheelchair-user interface in rehabilitation, daily life, and sports, further standardization of measurement set-ups and analyses is required. A crucial stepping-stone is the accurate measurement and standardization of external power output (measured in Watts), which is pivotal for the interpretation and comparison of experiments aiming to improve rehabilitation practice, activities of daily living, and adaptive sports. The different methodologies and advantages of accurate power output determination during overground, treadmill, and ergometer-based testing are presented and discussed in detail. Overground propulsion provides the most externally valid mode for testing, but standardization can be troublesome. Treadmill propulsion is mechanically similar to overground propulsion, but turning and accelerating is not possible. An ergometer is the most constrained and standardization is relatively easy. The goal is to stimulate good practice and standardization to facilitate the further development of theory and its application among research facilities and applied clinical and sports sciences around the world.

Accurate and standardized assessment of external power output is crucial in the evaluation of physiological, biomechanical, and perceived stress, strain, and capacity in manual wheelchair propulsion. The current article presents various methods to determine and control power output during wheelchair propulsion studies in the laboratory and beyond.

The use of a manual wheelchair is critical to 1% of the world&#39;s population. Human powered wheeled mobility research has considerably matured, which ...