This study was supported by NIH grants R21HL118661, R56HL124444, and R01HL124444 to CDK, and by NIH grants R00HL103797 and R01HL125695 to JMM.

All animal experiments were performed according to protocol approved by the Duke Institutional Animal Care and Use Committee. Male mice were used in this study, although either sex can be used as indicated for the scientific purpose of the study.
1. Hair Removal
<ol>
	<li>Prior to induction of anesthesia, set up a pre-surgical preparation area consisting of a covered heating pad set at 37 °C and a nosecone port connected to continuous flow of isoflurane.</li>
	<li>Place the mouse in the anesthesia induction chamber. Set the O2 flow meter to 1 L/min and isoflurane to 1 - 3%. 
	NOTE: Anesthesia is typically induced in a 25 g mouse with 2% isoflurane.</li>
	<li>Check the mouse's stimulus response by gently rocking the chamber and observing a lack of a righting reflex.</li>
	<li>Flush the chamber with O2 to clear the isoflurane prior to opening. Quickly move the mouse to the heating pad and connect it to isoflurane via the nosecone.</li>
	<li>Adjust the isoflurane to 1.5%. Check the stimulus response by pedal reflex (toe pinch).</li>
	<li>Apply ophthalmic lubricant liberally to both eyes to avoid drying during surgery.</li>
	<li>Shave the hair from both hind limbs using a small electric trimmer. Hold the skin taut while shaving to avoid lacerating the skin.</li>
	<li>Apply pre-warmed hair removal cream and let sit for 1 min. Gently wipe away using a moistened gauze pad.</li>
	<li>For surgical procedure at a later time, turn off the isoflurane and move the mouse to an empty paper towel-lined recovery cage to ensure the mouse does not aspirate the cage bedding. Monitor the animal until it is able to maintain sternal recumbency. Otherwise, move the mouse to the surgical table. 
	NOTE: The hair removal process can irritate the skin and affect perfusion measurements. It is recommended to wait 1 - 2 days after removing the animal's hair before performing a pre-surgical perfusion scan or performing surgery.</li>
</ol>
2. Pre-Surgical Preparation
<ol>
	<li>Use the following tools during this procedure; small straight surgical scissors, 2 fine-tipped angled forceps, small Graefe forceps, needle driver forceps, 3 retractors, small spring scissors, and fine-tipped cotton swabs.</li>
	<li>Sterilize all tools using an autoclave prior to the initiation of surgery. Use a hot-bead sterilizer before and between each surgical procedure, for up to 5 animals. Sterilize additional surgical tool packets for surgeries of groups larger than 5.</li>
	<li>Prepare a sterile surgical field consisting of a covered heating pad and an isoflurane port. Perform all work under a 10 stereo dissection microscope.</li>
	<li>Anesthetize and prepare the mouse as described in steps 1.1 to 1.5.</li>
	<li>Check that the mouse is fully sedated and place into a supine position on the surgical table. Secure both legs using surgical tape.</li>
	<li>If using a temperature-controlled heating pad, attach the temperature probe and secure it to the base of the surgical platform using surgical tape to ensure that it will not be accidentally pulled out during the procedure.</li>
	<li>Clean the incision site using 3 alternating povidone-iodine and alcohol wipes. Cover the animal with a sterile surgical drape and cut a hole to expose the incision site.</li>
</ol>
3. Induction of Limb Ischemia
<ol>
	<li>Use a scalpel to make an initial incision along the center of the medial thigh, running from the knee towards the abdomen, and lengthen the incision to approximately 1 cm with fine scissors (Figure 1A).</li>
</ol>
<img alt="Dissection diagram showing vascular anatomy in rodent leg, labeled arteries and veins for study." src="/files/ftp_upload/54166/54166fig1.jpg" data-altupdatedat="1747911167000" data-alt="Figure 1"> 
Figure 1. Surgical Site and Vascular Anatomical Landmarks for Mouse Hindlimb Ischemia Surgery. (A) External view of the hindlimb of a mouse in the supine position. The hatched line indicates the incision site to properly perform the hindlimb ischemia procedures. (B) View of the proximal mouse hindlimb vasculature. The proximal end of the femoral artery (FA) arises from beneath the inguinal ligament (IL). The distal end of the FA is located at its bifurcation into the popliteal artery (PA) and saphenous artery (SA). The major collateral arteries off of the FA are the lateral circumflex femoral artery (LCFA), the proximal caudal femoral artery (PCFA), and the superficial caudal epigastric artery (SCEA). The femoral vein (FV) runs adjacent to the FA, and venous branches can be seen parallel to the major arterial branches. Asterisks (*) denote the proximal and distal sites for placement of ameroid constrictors or ligatures, depending on whether subacute or acute ischemia will be induced. <a href="https://www.jove.com/files/ftp_upload/54166/54166fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<ol start="2">
	<li>Using forceps, open the incision and expose the membrane covering the inguinal fat tissue (IFT).</li>
	<li>Using closed-forceps, pierce through the membrane into the separation between the IFT and the abdomen. Gently release pressure on the forceps to separate the IFT from the abdominal muscles, exposing the neurovascular bundle underneath. Observe the proximal and superficial caudal branches as important anatomical landmarks (Figure 1B).</li>
	<li>Insert a retractor and pull the abdominal tissue proximally to expose the proximal ameroid constrictor or ligation site, just proximal to the lateral circumflex femoral artery (Figure 1B). The lateral circumflex artery lies about 5 mm proximal to the proximal and superficial caudal arteries.
	<ol>
		<li>Insert two more retractors into the distal part of the incision, one medial and one lateral, to pull the IFT distally away from the surgical site to widen the surgical field.</li>
	</ol>
	</li>
	<li>Use two fine forceps to remove the outermost membrane covering the neurovascular bundle. Gently insert one half of the fine forceps tip between the vein and artery, sliding the forceps tip under the membrane that binds them together. Close the forceps and gently tear away the membrane.</li>
	<li>Insert the tip of a closed forceps between the vein and artery and create a gap between them by releasing pressure on the forceps. Repeat this technique to create a gap between the artery and nerve.</li>
	<li>For subacute limb ischemia, place an ameroid constrictor on the proximal femoral artery (Figure 2).
	<ol>
		<li>To install the proximal ameroid constrictor, slide the tip of a forceps under the femoral artery to isolate it from the neurovascular bundle. Use a second set of angled- forceps to grip the edge of the constrictor and guide it under the femoral artery.</li>
		<li>Lay the femoral artery into the slot in the constrictor. Repeat for the distal constrictor, positioning it immediately proximal to the bifurcation of the femoral artery into the popliteal artery and saphenous artery (Figure 2).</li>
	</ol>
	</li>
</ol>
<img alt="Surgical procedure showing LCFA, PA, SA positioning; labeled image for vascular anatomy study." src="/files/ftp_upload/54166/54166fig2.jpg" data-altupdatedat="1747911167000" data-alt="Figure 2"> 
Figure 2. Placement of Ameroid Constrictors and Ligatures. (A) Example of two ameroid constrictors placed on the femoral artery to induce subacute hindlimb ischemia. The proximal constrictor is placed just proximal to the lateral circumflex femoral artery (LCFA). The distal constrictor is placed just proximal to the bifurcation of the popliteal (PA) and saphenous arteries (SA). Constrictors are installed with the slot facing up to ensure the artery is properly set within the constrictor. (B) Example of ligatures of the femoral artery to induce acute hindlimb ischemia. Ligatures (yellow arrows) are placed such that they flank the position of the constrictors in panel (B), and the femoral artery is transected between each set of two ligatures (asterisks). Bar, 1 mm. <a href="https://www.jove.com/files/ftp_upload/54166/54166fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<ol start="8">
	<li>For acute limb ischemia, ligate and transect the proximal femoral artery.
	<ol>
		<li>To transect the femoral artery, thread 7 - O suture under the artery just proximal to the position of the proximal constrictor (see Step 3.7) and ligate. Tie a second ligature about 1 mm distal to the first.</li>
		<li>Use spring scissors to transect the artery between the two ligatures. For the distal arterial transection, repeat these steps, placing two ligatures about 1 mm apart, just proximal to the bifurcation of the femoral artery into the popliteal artery and saphenous artery but ensuring that they are distal to the superficial caudal epigastric artery (see Figure 1)</li>
	</ol>
	</li>
	<li>Close the incision using interrupted 5 - O vicryl sutures.</li>
</ol>
4. Perfusion Imaging
<ol>
	<li>Move the mouse to a 37 °C heating pad set beneath the laser doppler perfusion imager (LDPI) and connect via a nosecone to the isoflurane source. If no temperature monitor is available, allow 5 min for the mouse to warm up to 37 °C.</li>
	<li>Turn on the imager and launch the image capture software.</li>
	<li>Click the 'New Single Image' icon to open the 'Scanner Setup' window. Set the 'Scan Size' to 'Large' and the 'Scan Speed' to '4 ms/pixel'. Set the scan area by changing the x and y values under the 'Scan Area (units)' pane.</li>
	<li>Click the 'Video and Distance' tab to view the video feed, and arrange the mouse to fit into the scan area indicated by a red outline. Click 'Auto Distance' to calibrate the distance from the laser to the subject. Click 'Next' to open the 'Subject Details' window.</li>
	<li>Enter the subject information and any relevant comments. Click the 'Next' button to move on to the scanning window.</li>
	<li>Click the 'Start Measurement' button to open the 'Confirm or Override Scan Distance' dialog. Click 'OK' to confirm scan distance. Observe the scanning process begin and run for 4 - 8 min depending on the size of the scan area.</li>
	<li>After the scanning is complete, observe the 'Save As' window. Name the file and save it.</li>
	<li>Shut off the isoflurane and move the mouse to an empty recovery cage and monitor until the animal is able to maintain sternal recumbency. Never place a mouse recovering from anesthesia into a cage with other mice.</li>
	<li>Open the image analysis software. Click the 'Open' icon and browse to and open the image file for analysis. On the file window, observe the flux, photo, and color images of the mouse.</li>
	<li>To mark the region of interest (ROI) on the flux image, click the 'Show ROIs' icon. Next click the 'Add Polygon' button and drag the cursor around the non-surgical limb to draw the ROI. Right-click to close the shape. Select 'Add Polygon' again and draw a matching ROI around the surgical limb.</li>
	<li>Click the 'Statistics' icon to open the 'Image ROIs Statistic Results (PU)' window. Observe the percent difference in flux in the 'Flux %' column. 
	NOTE: The first ROI drawn will serve as the reference. 
	NOTE: Prior to each subsequent perfusion scan follow the steps outlined in Section 1 to anesthetize the mouse and in steps 4.1 to 4.11 to image the animal.</li>
</ol>

<ol>
	<li>Criqui, M. H., Aboyans, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epidemiology+of+peripheral+artery+disease.">Epidemiology of peripheral artery disease.</a> Circ. Res. 116, 1509-1526 (2015).</li><li>Thukkani, A. K., Kinlay, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endovascular+intervention+for+peripheral+artery+disease.">Endovascular intervention for peripheral artery disease.</a> Circ. Res. 116, 1599-1613 (2015).</li><li>Vartanian, S. M., Conte, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surgical+intervention+for+peripheral+arterial+disease.">Surgical intervention for peripheral arterial disease.</a> Circ. Res. 116, 1614-1628 (2015).</li><li>Bonaca, M. P., Creager, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pharmacological+treatment+and+current+management+of+peripheral+artery+disease.">Pharmacological treatment and current management of peripheral artery disease.</a> Circ. Res. 116, 1579-1598 (2015).</li><li>Conte, 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=Design+and+rationale+of+the+PREVENT+III+clinical+trial:+edifoligide+for+the+prevention+of+infrainguinal+vein+graft+failure.">Design and rationale of the PREVENT III clinical trial: edifoligide for the prevention of infrainguinal vein graft failure.</a> Vasc Endovascular Surg. 39, 15-23 (2005).</li><li>Pomposelli, F. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+decade+of+experience+with+dorsalis+pedis+artery+bypass:+analysis+of+outcome+in+more+than+1000+cases.">A decade of experience with dorsalis pedis artery bypass: analysis of outcome in more than 1000 cases.</a> J. Vasc. Surg. 37, 307-315 (2003).</li><li>Willigendael, E. 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=Smoking+and+the+patency+of+lower+extremity+bypass+grafts:+a+meta-analysis.">Smoking and the patency of lower extremity bypass grafts: a meta-analysis.</a> J. Vasc. Surg. 42, 67-74 (2005).</li><li>Schillinger, 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=Balloon+angioplasty+versus+implantation+of+nitinol+stents+in+the+superficial+femoral+artery.">Balloon angioplasty versus implantation of nitinol stents in the superficial femoral artery.</a> N. Engl. J. Med. 354, 1879-1888 (2006).</li><li>Marmagkiolis, 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=12-month+primary+patency+rates+of+contemporary+endovascular+device+therapy+for+femoro-popliteal+occlusive+disease+in+6,024+patients:+beyond+balloon+angioplasty.">12-month primary patency rates of contemporary endovascular device therapy for femoro-popliteal occlusive disease in 6,024 patients: beyond balloon angioplasty.</a> Catheter. Cardiovasc. Interv. 84, 555-564 (2014).</li><li>Rosenfield, 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=Trial+of+a+Paclitaxel-Coated+Balloon+for+Femoropopliteal+Artery+Disease.">Trial of a Paclitaxel-Coated Balloon for Femoropopliteal Artery Disease.</a> N. Engl. J. Med. 373, 145-153 (2015).</li><li>Tepe, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Drug-coated+balloon+versus+standard+percutaneous+transluminal+angioplasty+for+the+treatment+of+superficial+femoral+and+popliteal+peripheral+artery+disease:+12-month+results+from+the+IN.PACT+SFA+randomized+trial.">Drug-coated balloon versus standard percutaneous transluminal angioplasty for the treatment of superficial femoral and popliteal peripheral artery disease: 12-month results from the IN.PACT SFA randomized trial.</a> Circulation. 131, 495-502 (2015).</li><li>Couffinhal, T., 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=Mouse+model+of+angiogenesis.">Mouse model of angiogenesis.</a> Am. J. Pathol. 152, 1667-1679 (1998).</li><li>Niiyama, H., Huang, N. F., Rollins, M. D., Cooke, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Murine+model+of+hindlimb+ischemia.">Murine model of hindlimb ischemia.</a> J Vis Exp. , (2009).</li><li>McClung, J. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Skeletal+muscle-specific+genetic+determinants+contribute+to+the+differential+strain-dependent+effects+of+hindlimb+ischemia+in+mice.">Skeletal muscle-specific genetic determinants contribute to the differential strain-dependent effects of hindlimb ischemia in mice.</a> Am. J. Pathol. 180, 2156-2169 (2012).</li><li>Dokun, A. O., 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+quantitative+trait+locus+(LSq-1)+on+mouse+chromosome+7+is+linked+to+the+absence+of+tissue+loss+after+surgical+hindlimb+ischemia.">A quantitative trait locus (LSq-1) on mouse chromosome 7 is linked to the absence of tissue loss after surgical hindlimb ischemia.</a> Circulation. 117, 1207-1215 (2008).</li><li>Rivard, 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=Age-dependent+impairment+of+angiogenesis.">Age-dependent impairment of angiogenesis.</a> Circulation. 99, 111-120 (1999).</li><li>Hazarika, 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=Impaired+angiogenesis+after+hindlimb+ischemia+in+type+2+diabetes+mellitus:+differential+regulation+of+vascular+endothelial+growth+factor+receptor+1+and+soluble+vascular+endothelial+growth+factor+receptor+1.">Impaired angiogenesis after hindlimb ischemia in type 2 diabetes mellitus: differential regulation of vascular endothelial growth factor receptor 1 and soluble vascular endothelial growth factor receptor 1.</a> Circ. Res. 101, 948-956 (2007).</li><li>Couffinhal, T., 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=Impaired+collateral+vessel+development+associated+with+reduced+expression+of+vascular+endothelial+growth+factor+in+ApoE-/-+mice.">Impaired collateral vessel development associated with reduced expression of vascular endothelial growth factor in ApoE-/- mice.</a> Circulation. 99, 3188-3198 (1999).</li><li>Tang, G. L., Chang, D. S., Sarkar, R., Wang, R., Messina, L. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+gradual+or+acute+arterial+occlusion+on+skeletal+muscle+blood+flow,+arteriogenesis,+and+inflammation+in+rat+hindlimb+ischemia.">The effect of gradual or acute arterial occlusion on skeletal muscle blood flow, arteriogenesis, and inflammation in rat hindlimb ischemia.</a> J. Vasc. Surg. 41, 312-320 (2005).</li><li>Yang, 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=Cellular+and+molecular+mechanism+regulating+blood+flow+recovery+in+acute+versus+gradual+femoral+artery+occlusion+are+distinct+in+the+mouse.">Cellular and molecular mechanism regulating blood flow recovery in acute versus gradual femoral artery occlusion are distinct in the mouse.</a> J. Vasc. Surg. 48, 1546-1558 (2008).</li><li>Litvak, J., Siderides, L. E., Vineberg, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+experimental+production+of+coronary+artery+insufficiency+and+occlusion.">The experimental production of coronary artery insufficiency and occlusion.</a> Am. Heart J. 53, 505-518 (1957).</li><li>Bredee, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+improved+ameroid+constrictor.+Preliminary+communication.">An improved ameroid constrictor. Preliminary communication.</a> J. Surg. Res. 9, 107-112 (1969).</li><li>McClung, J. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Subacute+limb+ischemia+induces+skeletal+muscle+injury+in+genetically+susceptible+mice+independent+of+vascular+density.">Subacute limb ischemia induces skeletal muscle injury in genetically susceptible mice independent of vascular density.</a> J. Vasc. Surg. , (2015).</li><li>Hellingman, A. 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=Variations+in+surgical+procedures+for+hind+limb+ischaemia+mouse+models+result+in+differences+in+collateral+formation.">Variations in surgical procedures for hind limb ischaemia mouse models result in differences in collateral formation.</a> Eur. J. Vasc. Endovasc. Surg. 40, 796-803 (2010).</li><li>Kochi, T., 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=Characterization+of+the+arterial+anatomy+of+the+murine+hindlimb:+functional+role+in+the+design+and+understanding+of+ischemia+models.">Characterization of the arterial anatomy of the murine hindlimb: functional role in the design and understanding of ischemia models.</a> PloS one. 8, e84047 (2013).</li></ol>

The authors have no conflicts of interest to disclose.

Perhaps the most challenging step in this procedure is the separation of the femoral artery from the femoral vein. The larger diameter and thinner walls of the femoral vein compared to those of the artery increase its susceptibility to puncture and tearing during surgical manipulation. The likelihood of disrupting the vein can be reduced by keeping the wound moist using a sterile swab moistened with PBS. It is also important to ensure that all forceps are sharpened, aligned, and free of breaks in order to allow precise m...

Peripheral artery disease (PAD) is a leading cause of cardiovascular morbidity and mortality in developed countries 1. PAD results from atherosclerotic obstruction of the peripheral arteries that leads to limb ischemia with resultant exertional or rest pain and occasionally non-healing ulcers and gangrene that necessitate limb amputation. Therapies targeting PAD are directed primarily towards endovascular 2 or surgical revascularization 3, as essentially no effective medical therapies exist 4.
Unfortunately, revascularization is often of limited benefit, as bypass grafts have high failure rates (up to 50% within 5 years) 5 that are worse in some populations (e.g., smokers, women, non-saphenous vein grafts) 6,7. Endovascular approaches, such as angioplasty and stenting, are also compromised by high restenosis rates (in excess of 50% within 1 year), particulary in femoropopliteal disease 8, although the use of drug-eluting balloons and stents has improved outcomes somewhat 9-11. In order to develop new treatments for PAD it is essential to develop animal models that reliably reproduce the human disease.
To date, the most common model of PAD is the hindlimb ischemia model (HLI), which is most frequently performed in mice 12,13. In its most common manifestation, the model entails surgical ligation of the proximal and distal femoral artery and its intervening side-branches followed by excision of the vessel, resulting in occlusion of blood flow and induction of acute limb ischemia. HLI has been used primarily to study the angiogenic and arteriogenic responses in peripheral limb muscle tissue and the effects of various therapies (e.g., drugs, gene delivery, stem cells) on these responses. More recently, our group has used this model to examine the role of skeletal muscle cells in the response to limb ischemia and the effects of genetic differences on outcomes 14.
The HLI model has facilitated our current understanding that the vascular and muscle responses to ischemia are dependent on genetics (i.e., inbred strain) 15, age 16, and the presence or absence of other diseases or conditions relevant to atherosclerosis, including diabetes mellitus 17 and hypercholesterolemia 18. However, an important weakness of the traditional HLI model is that it is a model of acute limb ischemia 12,13, whereas human PAD causes chronic ischemia as a result of the gradual development of occlusive atherosclerotic lesions in the peripheral arteries.
In an attempt to circumvent this weakness, Tang and colleagues initially developed a rat model of gradual femoral arterial occlusion using ameroid constrictors 19, and the same group subsequently developed a similar mouse model 20. Ameroid constrictors were described initially in the 1950s in a canine model of chronic myocardial ischemia 21,22. These devices have an outer metal sleeve encasing an inner layer of a hygroscopic material, usually casein, and when placed around an artery they induce gradual vessel occlusion as they absorb moisture from the surrounding tissues. In their modification of the model, Yang et al. placed constrictors on both the proximal and distal femoral artery at sites analogous to the surgical ligation sites, and they ligated the side branches of the femoral artery, as in the traditional model. Compared to acute HLI, ameroid constrictor-induced ischemia resulted in lower expression of inflammatory and shear stress-dependent genes, lower blood flow recovery 4 - 5 weeks post-operatively, and less muscle necrosis 20. Based on these observations, it was felt that gradual arterial occlusion might provide a model of PAD more relevant to the human disease.
Notably, in the original report, effects of ameroid constrictor-induced ischemia were examined only in C57BL/6 mice 19, which are relatively resistant to ischemia-induced muscle necrosis 15. We recently modified the gradual ischemia model further and explored its effects in the more ischemia-susceptible BALB/c mouse strain 23. In the first manifestation of the model, we placed constrictors on both the proximal and distal femoral artery but left all side-branches intact. In a second, milder modification, we placed a single constrictor only on the proximal femoral artery and again left all side-braches of the artery intact. In both modifications of this model, we found that BALB/c mice, but not C57BL/6 mice, displayed significant muscle necrosis despite having similar blood flow and vascular density. Similar to our previous study 14, these findings demonstrated that limb muscle injury is not solely influenced by blood flow, but is in part dependent on genetic background. Moreover, we found that limb blood flow fell to its nadir within 3 days, thus the model appears to be more one of &#39;subacute&#39; rather than gradual limb ischemia.
Based on these prior studies, it appears clear that a single method for inducing hindlimb ischemia may not be suitable in all cases. Because a variety of conditions (e.g., genetic differences and presence or absence of co-morbid conditions) influence both the vascular and skeletal muscle-specific responses, investigators may find it necessary to modify the chronicity and/or the severity of hindlimb ischemia to best suit their purposes. Furthermore, prior descriptions of the model typically lacked suitable anatomical landmarks to facilitate reliable inter-investigator reproducibility of the technique. In this paper, methods for inducing either acute or subacute hindlimb ischemia in the mouse are described, and precise anatomical landmarks are provided.

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methods for acute and subacute murine hindlimb ischemia

Peripheral artery disease (PAD) is a leading cause of cardiovascular morbidity and mortality in developed countries, and animal models that reliably reproduce the human disease are necessary to develop new therapies for this disease. The mouse hindlimb ischemia model has been widely used for this purpose, but the standard practice of inducing acute limb ischemia by ligation of the femoral artery can result in substantial tissue necrosis, compromising investigators&#39; ability to study the vascular and skeletal muscle tissue responses to ischemia. An alternative approach to femoral artery ligation is the induction of gradual femoral artery occlusion through the use of ameroid constrictors. When placed around the femoral artery in the same or different locations as the sites of femoral artery ligation, these devices occlude the artery over 1 - 3 days, resulting in more gradual, subacute ischemia. This results in less substantial skeletal muscle tissue necrosis, which may more closely mimic the responses seen in human PAD. Because genetic background influences outcomes in both the acute and subacute ischemia models, consideration of the mouse strain being studied is important in choosing the best model. This paper describes the proper procedure and anatomical placement of ligatures or ameroid constrictors on the mouse femoral artery to induce subacute or acute hindlimb ischemia in the mouse.

Proper identification of the mouse hindlimb vasculature is critical to ensuring reproducibility of the techniques for inducing both subacute and acute hindlimb ischemia, as described here. In addition to the variation inherent in animal studies, other factors can introduce variability in laser Doppler perfusion imaging (LDPI), including the type of anesthesia, position of the animal (supine vs. prone), and body temperature (see Figure 3). In addition, the subacut...

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Methods for Acute and Subacute Murine Hindlimb Ischemia

Surgical induction of hindlimb ischemia in the mouse is useful to examine angiogenesis, however this is compromised in certain inbred mouse strains that display marked ischemia-induced tissue necrosis. Methods are described to induce subacute limb ischemia using ameroid constrictors to circumvent this problem through the induction of gradual arterial occlusion.

Peripheral artery disease (PAD) is a leading cause of cardiovascular morbidity and mortality in developed countries, and animal models that reliably ...

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16.3K Views.  Duke University Medical Center. Surgical induction of hindlimb ischemia in the mouse is useful to examine angiogenesis, however this is compromised in certain inbred mouse strains that display marked ischemia-induced tissue necrosis. Methods are described to induce subacute limb ischemia using ameroid constrictors to circumvent this problem through the induction of gradual arterial occlusion. 

Video: Methods for Acute and Subacute Murine Hindlimb Ischemia

Coronary Artery Ligation and Intramyocardial Injection in a Murine Model of Infarction

Mouse models are a valuable tool for studying acute injury and chronic remodeling of the myocardium in vivo. With the advent of genetic modifications to the whole organism or the myocardium and an array of biological and/or synthetic materials, there is great potential for any combination of these to assuage the extent of acute ischemic injury and impede the onset of heart failure pursuant to myocardial remodeling. 
Here we present the methods and materials used to reliably perform this microsurgery and the modifications involved for temporary (with reperfusion) or permanent coronary artery occlusion studies as well as intramyocardial injections. The effects on the heart that can be seen during the procedure and at the termination of the experiment in addition to histological evaluation will verify efficacy. 
Briefly, surgical preparation involves anesthetizing the mice, removing the fur on the chest, and then disinfecting the surgical area. Intratracheal intubation is achieved by transesophageal illumination using a fiber optic light. The tubing is then connected to a ventilator. An incision made on the chest exposes the pectoral muscles which will be cut to view the ribs. For ischemia/reperfusion studies, a 1 cm piece of PE tubing placed over the heart is used to tie the ligature to so that occlusion/reperfusion can be customized. For intramyocardial injections, a Hamilton syringe with sterile 30gauge beveled needle is used. When the myocardial manipulations are complete, the rib cage, the pectoral muscles, and the skin are closed sequentially. Line block analgesia is effected by 0.25% marcaine in sterile saline which is applied to muscle layer prior to closure of the skin. The mice are given a subcutaneous injection of saline and placed in a warming chamber until they are sternally recumbent. They are then returned to the vivarium and housed under standard conditions until the time of tissue collection. At the time of sacrifice, the mice are anesthetized, the heart is arrested in diastole with KCl or BDM, rinsed with saline, and immersed in fixative. Subsequently, routine procedures for processing, embedding, sectioning, and histological staining are performed. 
Nonsurgical intubation of a mouse and the microsurgical manipulations described make this a technically challenging model to learn and achieve reproducibility. These procedures, combined with the difficulty in performing consistent manipulations of the ligature for timed occlusion(s) and reperfusion or intramyocardial injections, can also affect the survival rate so optimization and consistency are critical.

Numerous genetic manipulations and/or intramyocardial injections of genes, proteins, cells, and/or biomaterials are superimposed upon the dimension of time in studies of acute ischemia/ reperfusion injury and chronic remodeling in mice. This video illustrates the microsurgical procedures for ischemia/reperfusion, permanent coronary artery ligation, and intramyocardial injection studies.

Mouse models are a valuable tool for studying acute injury and chronic remodeling of the myocardium in vivo.  With the advent of genetic modifications to ...

Murine Model of Hindlimb Ischemia 

In the United States, peripheral arterial disease (PAD) affects about 10 million individuals, and is also prevalent worldwide. Medical therapies for symptomatic relief are limited. Surgical or endovascular interventions are useful for some individuals, but long-term results are often disappointing. As a result, there is a need for developing new therapies to treat PAD. The murine hindlimb ischemia preparation is a model of PAD, and is useful for testing new therapies. When compared to other models of tissue ischemia such as coronary or cerebral artery ligation, femoral artery ligation provides for a simpler model of ischemic tissue. Other advantages of this model are the ease of access to the femoral artery and low mortality rate. 
In this video, we demonstrate the methodology for the murine model of unilateral hindimb ischemia. The specific materials and procedures for creating and evaluating the model will be described, including the assessment of limb perfusion by laser Doppler imaging. This protocol can also be utilized for the transplantation and non-invasive tracking of cells, which is demonstrated by Huang et al.1.

Murine Model of Hindlimb Ischemia

The surgical procedure for induction of unilateral hindlimb ischemia is demonstrated, with confirmation of ischemia by laser Doppler perfusion imaging.

In the United States, peripheral arterial disease (PAD) affects about 10 million individuals, and is also prevalent worldwide.  Medical therapies for ...

Biology

Osmotic Drug Delivery to Ischemic Hindlimbs and Perfusion of Vasculature with Microfil for Micro-Computed Tomography Imaging

Preclinical research in animal models of peripheral arterial disease plays a vital role in testing the efficacy of therapeutic agents designed to stimulate microcirculation. The choice of delivery method for these agents is important because the route of administration profoundly affects the bioactivity and efficacy of these agents1,2. In this article, we demonstrate how to locally administer a substance in ischemic hindlimbs by using a catheterized osmotic pump. This pump can deliver a fixed volume of aqueous solution continuously for an allotted period of time. We also present our mouse model of unilateral hindlimb ischemia induced by ligation of the common femoral artery proximal to the origin of profunda femoris and epigastrica arteries in the left hindlimb. Lastly, we describe the in vivo cannulation and ligation of the infrarenal abdominal aorta and perfusion of the hindlimb vasculature with Microfil, a silicone radiopaque casting agent. Microfil can perfuse and fill the entire vascular bed (arterial and venous), and because we have ligated the major vascular conduit for exit, the agent can be retained in the vasculature for future ex vivo imaging with the use of small specimen micro-CT3.

We show here the in vivo insertion of an osmotic pump for constant local drug delivery and the creation of hindlimb ischemia in a mouse model. Moreover, the hindlimb vasculature is perfused with Microfil, a silicone radiopaque agent, to prepare for micro-computed tomography (micro-CT) imaging.

Preclinical research in animal models of peripheral arterial disease plays a vital role in testing the efficacy of therapeutic agents designed to ...

Reproducable Paraplegia by Thoracic Aortic Occlusion in a Murine Model of Spinal Cord Ischemia-reperfusion

Background 
Lower extremity paralysis continues to complicate aortic interventions. The lack of understanding of the underlying pathology has hindered advancements to decrease the occurrence this injury.&#160;The current model demonstrates reproducible lower&#160;extremity paralysis following thoracic aortic occlusion.
Methods 
Adult male C57BL6 mice were anesthetized with isoflurane. Through a cervicosternal incision the aorta was exposed. The descending thoracic aorta and left subclavian arteries were identified without entrance into pleural space. Skeletonization of these arteries was followed by immediate closure (Sham) or occlusion for 4 min (moderate ischemia) or 8 min (prolonged ischemia). The sternotomy and skin were closed and the mouse was transferred to warming bed for recovery.&#160; Following recovery, functional analysis was obtained at 12 hr intervals until 48 hr.
Results 
Mice that underwent sham surgery showed no observable hind&#160;limb deficit. Mice subjected to moderate ischemia for 4 min had minimal functional deficit at 12 hr followed by progression to complete paralysis at 48 hr. Mice subjected to prolonged ischemia had an immediate paralysis with no observable hind-limb movement at any point in the postoperative period. There was no observed intraoperative or post&#160;operative mortality.
Conclusion 
Reproducible lower extremity paralysis whether immediate or delayed can be achieved in a murine model. Additionally, by using a median sternotomy and careful dissection, high survival rates, and reproducibility can be achieved.

The lack of mechanistic understanding of spinal cord ischemia-reperfusion injury has hindered further adjuncts to prevent paraplegia following high risk aortic operations. Thus, the development of animal models is imperative. This manuscript demonstrates reproducible lower extremity paralysis following thoracic aortic occlusion in a murine model.

Background
Lower extremity paralysis continues to complicate aortic interventions. The lack of understanding of the underlying pathology has hindered ...

A Murine Model of Myocardial Ischemia-reperfusion Injury through Ligation of the Left Anterior Descending Artery

Acute or chronic myocardial infarction (MI) are cardiovascular events resulting in high morbidity and mortality. Establishing the pathological mechanisms at work during MI and developing effective therapeutic approaches requires methodology to reproducibly simulate the clinical incidence and reflect the pathophysiological changes associated with MI. Here, we describe a surgical method to induce MI in mouse models that can be used for short-term ischemia-reperfusion (I/R) injury as well as permanent ligation. The major advantage of this method is to facilitate location of the left anterior descending artery (LAD) to allow for accurate ligation of this artery to induce ischemia in the left ventricle of the mouse heart. Accurate positioning of the ligature on the LAD increases reproducibility of infarct size and thus produces more reliable results. Greater precision in placement of the ligature will improve the standard surgical approaches to simulate MI in mice, thus reducing the number of experimental animals necessary for statistically relevant studies and improving our understanding of the mechanisms producing cardiac dysfunction following MI. This mouse model of MI is also useful for the preclinical testing of treatments targeting myocardial damage following MI.

We introduce a surgical method to induce experimental ischemia/reperfusion (I/R) injury to simulate myocardial infarction (MI) in mouse models that allows for more clarity in positioning of the ligation on the left anterior descending artery (LAD) to increase the reproducibility of MI experiments in mice.

Acute or chronic myocardial infarction (MI) are cardiovascular events resulting in high morbidity and mortality. Establishing the pathological mechanisms ...

Induction of Ischemic Stroke and Ischemia-reperfusion in Mice Using the Middle Artery Occlusion Technique and Visualization of Infarct Area

Cerebrovascular disease is highly prevalent in the global population and encompasses several types of conditions, including stroke. To study the impact of stroke on tissue injury and to evaluate the effectiveness of therapeutic interventions, several experimental models in a variety of species were developed. They include complete global cerebral ischemia, incomplete global ischemia, focal cerebral ischemia, and multifocal cerebral ischemia. The model described in this protocol is based on the middle cerebral artery occlusion (MCAO) and is related to the focal ischemia category. This technique produces consistent focal ischemia in a strictly defined region of the hemisphere and is less invasive than other methods. The procedure described is performed on mice, given the availability of several genetic variants and the high number of tests standardized for mice to aid in the behavioral and neurodeficit evaluation.

We describe a mouse model of stroke induced by the occlusion of the middle cerebral artery using a silicone coated suture. The protocol can be applied to induce permanent occlusion or a temporary ischemia, followed by reperfusion.

Cerebrovascular disease is highly prevalent in the global population and encompasses several types of conditions, including stroke. To study the impact of ...

Assessing Therapeutic Angiogenesis in a Murine Model of Hindlimb Ischemia

Critical limb ischemia (CLI) is a serious condition that entails a high risk of lower limb amputation. Despite revascularization being the gold-standard therapy, a considerable number of CLI patients are not suited for either surgical or endovascular revascularization. Angiogenic therapies are emerging as an option for these patients but are currently still under investigation. Before application in humans, those therapies must be tested in animal models and its mechanisms must be clearly understood. An animal model of hindlimb ischemia (HLI) has been developed by the ligation and excision of the distal external iliac and femoral arteries and veins in mice. A comprehensive panel of tests was assembled to assess the effects of ischemia and putative angiogenic therapies at functional, histologic and molecular levels. Laser Doppler was used for the flow measurement and functional assessment of perfusion. Tissue response was evaluated by the analysis of capillary density after staining with the anti-CD31 antibody on histological sections of gastrocnemius muscle and by measurement of collateral vessel density after diaphonization. Expression of angiogenic genes was quantified by RT-PCR targeting selected angiogenic factors exclusively in endothelial cells (ECs) after laser capture microdissection from mice gastrocnemius muscles. These methods were sensitive in identifying differences between ischemic and non-ischemic limbs and between treated and non-treated limbs. This protocol provides a reproducible model of CLI and a framework for testing angiogenic therapies.

Here, a critical hindlimb ischemia experimental model is presented followed by a battery of functional, histologic and molecular tests&#160;to assess the effectiveness of angiogenic therapies.&#8203;

Critical limb ischemia (CLI) is a serious condition that entails a high risk of lower limb amputation. Despite revascularization being the gold-standard ...

Laser Doppler Perfusion Imaging in the Mouse Hindlimb

Blood flow recovery is a critical outcome measure after experimental hindlimb ischemia or ischemia-reperfusion. Laser Doppler perfusion imaging (LDPI) is a common, noninvasive, repeatable method for assessing blood flow recovery. The technique calculates overall blood flow in the sampled tissue from the Doppler shift in frequency caused when a laser hits moving red blood cells. Measurements are expressed in arbitrary perfusion units, so the contralateral non-intervened upon leg is usually used to help control measurements. Measurement depth is in the range of 0.3-1 mm; for hindlimb ischemia, this means that dermal perfusion is assessed. Dermal perfusion is dependent on several factors&#8212;most importantly skin temperature and anesthetic agent, which must be carefully controlled to result in reliable readings. Furthermore, hair and skin pigmentation can alter the ability of the laser to either reach or penetrate to the dermis. This article demonstrates the technique of LDPI in the mouse hindlimb.

Here, we present a protocol that demonstrates the technique and necessary controls for Laser Doppler perfusion imaging to measure blood flow in the mouse hindlimb.

Blood flow recovery is a critical outcome measure after experimental hindlimb ischemia or ischemia-reperfusion. Laser Doppler perfusion imaging (LDPI) is ...

High-Resolution Three-Dimensional Imaging of the Footpad Vasculature in a Murine Hindlimb Gangrene Model

Peripheral arterial disease (PAD) is a significant cause of morbidity resulting from chronic exposure to atherosclerotic risk factors. Patients suffering from its most severe form, chronic limb-threatening ischemia (CLTI), face substantial impairments to daily living, including chronic pain, limited walking distance without pain, and nonhealing wounds. Preclinical models have been developed in various animals to study PAD, but mouse hindlimb ischemia remains the most widely used. There can be significant variation in response to ischemic insult in these models depending on the mouse strain used and the site, number, and means of arterial disruption. This protocol describes a unique method combining femoral artery and vein electrocoagulation with the administration of a nitric oxide synthase (NOS) inhibitor to reliably induce footpad gangrene in Friend Virus B (FVB) mice that resembles the tissue loss of CLTI. While traditional means of assessing reperfusion such as laser Doppler perfusion imaging (LDPI) are still recommended, intracardiac perfusion of the lipophilic dye 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) is used to label the vasculature. Subsequent whole-mount confocal laser scanning microscopy allows for high-resolution, three-dimensional (3D) reconstruction of footpad vascular networks that complements traditional means of assessing reperfusion in hindlimb ischemia models.

The present protocol describes a unique, clinically relevant model of peripheral arterial disease that combines femoral artery and vein electrocoagulation with the administration of a nitric oxide synthase inhibitor to induce hindlimb gangrene in FVB mice. Intracardiac DiI perfusion is then used for high-resolution, three-dimensional imaging of the footpad vasculature.

Peripheral arterial disease (PAD) is a significant cause of morbidity resulting from chronic exposure to atherosclerotic risk factors. Patients suffering ...

Occlusion of Distal Middle Artery to Develop an Ischemic Stroke Mouse Model

Induction of Acute Ischemic Stroke in Mice Using the Distal Middle Artery Occlusion Technique

Ischemic stroke remains the predominant cause of mortality and functional impairment among the adult populations globally. Only a minority of ischemic stroke patients are eligible to receive intravascular thrombolysis or mechanical thrombectomy therapy within the optimal time window. Among those stroke survivors, around two-thirds suffer neurological dysfunctions over an extended period. Establishing a stable and repeatable experimental ischemic stroke model is extremely significant for further investigating the pathophysiological mechanisms and developing effective therapeutic strategies for ischemic stroke. The middle cerebral artery (MCA) represents the predominant location of ischemic stroke in humans, with the MCA occlusion serving as the frequently employed model of focal cerebral ischemia. In this protocol, we describe the methodology of establishing the distal MCA occlusion (dMCAO) model through transcranial electrocoagulation in C57BL/6 mice. Since the occlusion site is located at the cortical branch of MCA, this model generates a moderate infarcted lesion restricted to the cortex. Neurological behavioral and histopathological characterization have demonstrated visible motor dysfunction, neuron degeneration, and pronounced activation of microglia and astrocytes in this model. Thus, this dMCAO mouse model provides a valuable tool for investigating the ischemiastroke and worth of popularization.

Author Spotlight: Establishing a Reliable Distal MCA Occlusion Model in Mice for Stroke Research

Here, we present a protocol to establish a distal middle cerebral artery occlusion (dMCAO) model through transcranial electrocoagulation in C57BL/6J mice and evaluate the subsequent neurological behavior and histopathological features.

Ischemic stroke remains the predominant cause of mortality and functional impairment among the adult populations globally. Only a minority of ischemic ...

Methods for Acute and Subacute Murine Hindlimb Ischemia

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