The authors would like to acknowledge funding support from the University of South Florida, Department of Surgery (Mack Wu, MD, PhD).

NOTE: Approval for all animal procedures presented below was obtained from the University of South Florida&#8217;s Animal Care Committee (IACUC) and abide by all requirements of the Animal Welfare Act and the Guide for Care and Use of Laboratory Animals.
1. Preparation of Silicone Sheets and Surgical Instruments
<ol>
	<li>Precut strips (10.5 cm x 3.0 cm) of non-reinforced 0.01 thickness, medical grade silicone sheeting and sterilize using an autoclave.</li>
	<li>Clean and sterilize suitable surgical instruments (scissors, forceps and drapes or towels to create a sterile field during surgery).</li>
</ol>
2. Experimental Animals
<ol>
	<li>Use adult male or female rats weighing in range from 250-350 g obtained from a commercial breeder. If aged rats are utilized, they should be &#8805;350 g in order to ensure better survival post-surgery. Prior to the start of any experiments acclimate all animals for at least 7 days under standard conditions of a 12 hr light-dark cycle with food and water ad libitum.</li>
</ol>
3. Anesthesia, Pre-operative Analgesia and Operative Preparation
<ol>
	<li>Induce general anesthesia by using isoflurane at 3%-4% via an induction chamber and maintain (via use of a nose cone) at 1%-2% with O2 during skin preparation and surgery. Monitor the depth of anesthesia by observation of the rate and depth of respiration, interdigital pinch or palpebral blink reflex. 
	NOTE: At this time, a vet ointment can be placed on the eyes to prevent dryness while the animal is under anesthesia.</li>
	<li>In a location remote from the sterile surgical area, place the rat in the prone position and shave the dorsum with clippers from the base of the neck down approximately 11 cm. Stencil with permanent marker, the outline for the 3.0 cm x 10.5 cm flap (see Figure 1A).</li>
	<li>Move the rat to a clean, designated surgical area equipped with an approved heating pad and sterile surgical drapes or towels. Inject 5 mg/kg Ketoprofen subcutaneously prior to the first surgical incisions for pain management. Additional fluids (saline) can be given (up to 5 cc) subcutaneously as needed.</li>
	<li>Prepare the skin further by swabbing first with 70% isopropyl alcohol and second with 0.2% chlorhexidine, then apply sterile drapes to create a sterile field. 10% povidone-iodine (Betadine) can also be used. 
	NOTE: An antibiotic (ampicillin at 15 mg/kg) can be administered subcutaneously, but if good aseptic techniques are used it is not required.</li>
</ol>
4. Creating Excisional Wounds and Bipedicled Flap
<ol>
	<li>Using a sterile, disposable 6 mm biopsy punch tool, create two circular &#8220;ischemic&#8221; wounds in the center of the designated flap area (Figure 1B). The depth of the wound should be down to (not through) the underlying fascia of the panniculus carnosus muscle (Figure 1B inset).</li>
	<li>Using forceps lift the skin in the middle of the wound outline created by the punch biopsy and then use iris scissors (with curved tips) to excise the circular piece of tissue (including the panniculus carnosus muscle). The result will be a full-thickness wound with the fascia as the base of the wound. 
	NOTE: The excised tissue (wound plugs) can be snap frozen in liquid nitrogen or fixed in 10% buffered-formalin O/N for later processing as control, normal skin.</li>
	<li>Create a bipedicled flap by making incisions with a sterile scalpel on each side of the ischemic wounds along the pre-drawn lines (Figure 1C) that are 10.5 cm in length and 3.0 cm apart. The depth of the incisions should be down to the paraspinous muscles. Using iris scissors, separate the panniculus carnosus fascia from the paraspinous muscles, being careful to keep the fascia intact as the &#8220;base&#8221; of the 6 mm punches (Figure 1D).</li>
	<li>Take 1 sterile pre-cut silicone sheet and place it in between the panniculus carnosus fascia and the paraspinous muscles (Figure 1E) ensuring that the sheet does not buckle or fold. Using black, non-absorbable sutures (size 4.0) close both incisions by anchoring the silicone sheet to the skin with at least 8 interrupted stitches on each side, along the length of the flap (Figure 1F and 1G).</li>
	<li>Using a sterile, disposable biopsy punch tool, create two internal control &#8220;non-ischemic&#8221; wounds (down to the anterior fascia of the panniculus carnosus muscle) 1 cm lateral to the ischemic wounds on either side of the flap (Figure 1G).</li>
	<li>Place a ruler below the wounds and take digital photos for wound measurement purposes (see Figure 3A). At this time, blood flow (perfusion) can be monitored by use of laser Doppler or other manipulations (topical drug placement) performed.</li>
	<li>Apply an approved liquid adhesive both cranial and caudal to the wounds and a transparent film dressing to keep the wound environment moist and clean (sterile). An additional dressing may be placed at the caudal end of the flap to prevent the animal from removing the most caudal sutures.</li>
</ol>
5. Post-operative Procedures
<ol>
	<li>Place animals in cages (singly housed) equipped with shallow feeders so as to prevent the surgical site from rubbing against the feeder. Animals should not be left unattended or returned to the company of other animals until they regain sufficient consciousness to maintain sternal recumbency and exhibit purposeful movement. Heating mats should be placed under half of the cage for up to 2 days during recovery.</li>
	<li>To manage pain post-operatively, administer Ketoprofen (5 mg/kg) subcutaneously to animals the following morning and 1x per day for up to 48 hr post-surgery. Animals should also be monitored daily for prolonged signs of pain, weight loss or surgical site infections.</li>
</ol>
6. Subsequent Wound Measurements and Dressing Changes
<ol>
	<li>Measure ischemic and non-ischemic wounds frequently under general anesthesia using isoflurane at 3%-4% via an induction chamber and maintained (via a nose cone) at 1%-2% with O2 as in step 3.1.</li>
	<li>Remove the dressing gently as to not pull the adhesive from the skin. At this time additional digital photos are taken for wound measurements, topical treatments re-applied, laser Doppler imaging (LDI) or other manipulations performed to suit the investigator&#8217;s needs.</li>
	<li>Apply adhesive and a clean dressing and allow the animal to recover as in step 5.1.</li>
</ol>
7. Wound Collection and Euthanasia
<ol>
	<li>Harvest ischemic and non-ischemic wounds (on days the investigator deems appropriate) while the animal is under general anesthesia using isoflurane at 3%-4% via an induction chamber and maintained (via a nose cone) at 1%-2% with O2 as in step 3.1.</li>
	<li>Using a scalpel, make a square shaped excision around the wound to include some healthy tissue around the wound. Place the excision into a 1.5 ml snap cap tube and snap freeze in liquid nitrogen (store at -80 &#176;C) for future molecular analysis or incubate in 10% buffered formalin O/N at RT for histological processing. 
	NOTE: The wound excisions can also be cut in half to provide more samples for analysis.</li>
	<li>After wound tissue removal, euthanize the animal using the approved method of CO2 inhalation.</li>
</ol>

<ol>
	<li>Ansell, D. M., Holden, K. A., Hardman, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+of+wound+repair:+Are+they+cutting+it.">Animal models of wound repair: Are they cutting it.</a> Experimental dermatology. 21 (8), 581-585 (2012).</li><li>Dorsett-Martin, W. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rat+models+of+skin+wound+healing:+a+review.">Rat models of skin wound healing: a review.</a> Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society. 12 (6), 591-599 (2003).</li><li>Davidson, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+for+wound+repair.">Animal models for wound repair.</a> Arch Dermatol Res. 290 (S1-11), (1998).</li><li>Finn, G., Magnus, S. A., Tonny, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Models+for+use+in+wound+healing+research:+A+survey+focusing+on+in+vitro+and+in+vivo+adult+soft+tissue).">Models for use in wound healing research: A survey focusing on in vitro and in vivo adult soft tissue).</a> Wound Repair and Regeneration. 8, (2000).</li><li>Gould, L. J., Leong, M., Sonstein, J., Wilson, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimization+and+validation+of+an+ischemic+wound+model.">Optimization and validation of an ischemic wound model.</a> Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society. 13 (6), 576-582 (2004).</li><li>Loots, M. 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=Differences+in+cellular+infiltrate+and+extracellular+matrix+of+chronic+diabetic+and+venous+ulcers+versus+acute+wounds.">Differences in cellular infiltrate and extracellular matrix of chronic diabetic and venous ulcers versus acute wounds.</a> The Journal of investigative dermatology. 111 (5), 850-857 (1998).</li><li>Schwartz, D. A., Lindblad, W. J., Rees, R. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Altered+collagen+metabolism+and+delayed+healing+in+a+novel+model+of+ischemic+wounds.">Altered collagen metabolism and delayed healing in a novel model of ischemic wounds.</a> Wound Repair Regen. 3 (2), 204-212 (1995).</li><li>Chen, 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=Molecular+and+mechanistic+validation+of+delayed+healing+rat+wounds+as+a+model+for+human+chronic+wounds.">Molecular and mechanistic validation of delayed healing rat wounds as a model for human chronic wounds.</a> Wound Repair and Regeneration. 7, (1999).</li><li>Zhang, Q., Chang, Q., Cox, R. A., Gong, X., Gould, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hyperbaric+oxygen+attenuates+apoptosis+and+decreases+inflammation+in+an+ischemic+wound+model.">Hyperbaric oxygen attenuates apoptosis and decreases inflammation in an ischemic wound model.</a> The Journal of investigative dermatology. 128 (8), 2102-2112 (2008).</li><li>Zhang, Q., Gould, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hyperbaric+oxygen+reduces+matrix+metalloproteinases+in+ischemic+wounds+through+a+redox-dependent+mechanism.">Hyperbaric oxygen reduces matrix metalloproteinases in ischemic wounds through a redox-dependent mechanism.</a> The Journal of investigative dermatology. 134 (1), 237-246 (2013).</li><li>Moor, A. N., 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=Consequences+of+age+on+ischemic+wound+healing+in+rats:+altered+antioxidant+activity+and+delayed+wound+closure.">Consequences of age on ischemic wound healing in rats: altered antioxidant activity and delayed wound closure.</a> Age (Dordrecht, Netherlands). 36 (2), 733-748 (2014).</li><li>Roy, 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=Characterization+of+a+preclinical+model+of+chronic+ischemic+wound).">Characterization of a preclinical model of chronic ischemic wound).</a> Physiological genomics. 37 (3), 211-224 (2009).</li><li>Biswas, 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=Hypoxia+inducible+microRNA+210+attenuates+keratinocyte+proliferation+and+impairs+closure+in+a+murine+model+of+ischemic+wounds.">Hypoxia inducible microRNA 210 attenuates keratinocyte proliferation and impairs closure in a murine model of ischemic wounds.</a> Proceedings of the National Academy of Sciences of the United States of America. 107 (15), 6976-6981 (2010).</li><li>Winocour, S., Vorstenbosch, J., Trzeciak, A., Lessard, L., Philip, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CD109,+a+novel+TGF-beta+antagonist,+decreases+fibrotic+responses+in+a+hypoxic+wound+model.">CD109, a novel TGF-beta antagonist, decreases fibrotic responses in a hypoxic wound model.</a> Exp Dermatol. 23 (7), 475-479 (2014).</li></ol>

The authors have nothing to disclose.

Wound healing in rats has often been the subject of debate due to their ability to heal infected wounds and high rate of interanimal variability5. One of the original goals of the model during its development was to decrease this variation. Modifications to the width of the flap, reducing the number of wounds with specific placement (centered on the flap with consistent cranio-caudal location) and introduction of a silicone sheet has accomplished this goal. Wound healing by contraction has also been reduced an...

Effective drug development and other wound healing therapeutics require appropriate in vivo models, despite known problems in translating findings in animal models to human therapies1. What follows is a description of a detailed protocol for the use of a rat model of ischemic skin wound healing to investigate mechanisms that further the understanding of pathological wound healing. The rat species, often employed due to its wide availability, size and docile nature is used for wound healing studies as it is large enough to provide a suitable skin area for incisional and excisional wounding, imaging and tissue collection2. However it should be taken into careful consideration that the skin of a rat and a human are different anatomically, with rats being referred to as loose-skinned animals. This distinct characteristic allows for wound contraction, rather than epithelialization to contribute significantly to the closing of rat skin wounds2. Additionally, the presence of a subcutaneous panniculus carnosus muscle in rats, contributes to healing by both contraction and collagen formation3,4. These very important anatomical distinctions were considered in the development of the rat ischemic skin wound model and specific modifications were implemented to decrease wound contraction and reduce the influence of the panniculus carnosus muscle5.
In diabetic foot ulcers, venous leg ulcers, and pressure ulcers, healing is delayed and these wounds are considered chronic. The wounds are characterized by excessive inflammation, which prevents the wound from progressing to the next phases of wound repair6. One of the main factors in the development of a chronic wound is localized tissue ischemia (reduced blood flow)5 contributing to the inability to clear inflammation. At the time during which this model was being developed and validated (in 2003-4), there were no standardized animal models that could provide enough tissue to test induction of angiogenesis in the wound bed, a key stage during normal wound healing and the motivation for developing this model5. That said, the model presented here is a modification of the ischemic wound model originally described by Schwartz et al.7 and subsequently used in modified form by Chen et al.8
In the modified ischemic wound model, changes have been made to circumvent the above mentioned anatomical characteristics of the rat that lead to healing by contraction rather than epithelialization: (1) Two full-thickness excisional wounds are created within a bipedicled dorsal skin flap and the panniculus carnosus muscle is removed from the wound bed by dissecting just above the muscle fascia. (2) The flap itself has more narrow dimensions, ensuring that blood supply is random and the wounds located at the midpoint of the flap are ischemic. (3) A silicone sheet is inserted beneath the flap, preventing readherence and reperfusion of the flap from underlying tissue. Wound contraction is limited (not eliminated) by anchoring or suturing the flap to the silicone sheet5.
The model has recently been used in studies ranging from hyperbaric oxygen effects on ischemic wound healing9,10 to ischemic wound healing in young versus aged rats11 and has proven to be a reliable model of prolonged tissue ischemia. The dimensions of the bipedicled flap have also been adapted to different rat strains, including Sprague Dawley (11 cm long by 2 cm wide) and F344 rats (10.5 cm long by 3.0-3.5 cm wide) and other species, including swine12 and mice13,14 . This video utilizes the F344 inbred rat strain in the demonstration of the ischemic skin wound model.
Approval for all animal procedures presented below was obtained from the University of South Florida&#8217;s Animal Care Committee (IACUC) and abide by all requirements of the Animal Welfare Act and the Guide for Care and Use of Laboratory Animals.

<table border="0" cellpadding="0" cellspacing="0" width="605">
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			<td>Standard blood flow imager: http://us.moor.co.uk/product/moorldi2-laser-doppler-imager/8</td>
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demonstration of the rat ischemic skin wound model

The propensity for chronic wounds in humans increases with ageing, disease conditions such as diabetes and impaired cardiovascular function, and unrelieved pressure due to immobility. Animal models have been developed that attempt to mimic these conditions for the purpose of furthering our understanding of the complexity of chronic wounds. The model described herein is a rat ischemic skin flap model that permits a prolonged reduction of blood flow resulting in wounds that become ischemic and resemble a chronic wound phenotype (reduced vascularization, increased inflammation and delayed wound closure). It consists of a bipedicled dorsal flap with 2 ischemic wounds placed centrally and 2 non-ischemic wounds lateral to the flap as controls. A novel addition to this ischemic skin flap model is the placement of a silicone sheet beneath the flap that functions as a barrier and a splint to prevent revascularization and reduce contraction as the wounds heal. Despite the debate of using rats for wound healing studies due to their quite distinct anatomic and physiologic differences compared to humans (i.e., the presence of a panniculus carnosus muscle, short life-span, increased number of hair follicles, and their ability to heal infected wounds) the modifications employed in this model make it a valuable alternative to previously developed ischemic skin flap models.

The rat ischemic wound healing model protocol should take approximately 20 min&#160;per animal if performed efficiently. Prior to application of a dressing the model should appear as represented in Figure 1G. It will be important to verify that the bipedicled flap and wounds therein are ischemic. Subcutaneous oxygen tension (PscO2) at the level of the wounds has been measured during validation of this model5 by placing a polarographic electrode in the subcutaneous tissue between the...

Watch this Scientific Journal Video about Demonstration of the Rat Ischemic Skin Wound Model at JoVE.com

Demonstration of the Rat Ischemic Skin Wound Model

The rat, due to its size, availability, and rather docile behavior, has been utilized as a research model for many years. The goal of this protocol is to utilize the rat as an ischemic skin wound healing model to provide valuable insight into the pathophysiology of chronic wounds.

The propensity for chronic wounds in humans increases with ageing, disease conditions such as diabetes and impaired cardiovascular function, and ...

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21.1K Views.  University of South Florida. The rat, due to its size, availability, and rather docile behavior, has been utilized as a research model for many years. The goal of this protocol is to utilize the rat as an ischemic skin wound healing model to provide valuable insight into the pathophysiology of chronic wounds.

Video: Demonstration of the Rat Ischemic Skin Wound Model

Accurate and Simple Measurement of the Pro-inflammatory Cytokine IL-1&beta; using a Whole Blood Stimulation Assay

Inflammatory processes resulting from the secretion of soluble mediators by immune cells, lead to various manifestations in skin, joints and other tissues as well as altered cytokine homeostasis. The innate immune system plays a crucial role in recognizing pathogens and other endogenous danger stimuli. One of the major cytokines released by innate immune cells is Interleukin (IL)-1. Therefore, we utilize a whole blood stimulation assay in order to measure the secretion of inflammatory cytokines and specifically of the pro-inflammatory cytokine IL-1&beta; 1, 2, 3.
Patients with genetic dysfunctions of the innate immune system causing autoinflammatory syndromes show an exaggerated release of mature IL-1&beta; upon stimulation with LPS alone. In order to evaluate the innate immune component of patients who present with inflammatory-associated pathologies, we use a specific immunoassay to detect cellular immune responses to pathogen-associated molecular patterns (PAMPs), such as the gram-negative bacterial endotoxin, lipopolysaccharide (LPS). These PAMPs are recognized by pathogen recognition receptors (PRRs), which are found on the cells of the innate immune system 4, 5, 6, 7. A primary signal, LPS, in conjunction with a secondary signal, ATP, is necessary for the activation of the inflammasome, a multiprotein complex that processes pro-IL-1&beta; to its mature, bioactive form 4, 5, 6, 8, 9, 10.
The whole blood assay requires minimal sample manipulation to assess cytokine production when compared to other methods that require labor intensive isolation and culturing of specific cell populations. This method differs from other whole blood stimulation assays; rather than diluting samples with a ratio of RPMI media, we perform a white blood cell count directly from diluted whole blood and therefore, stimulate a known number of white blood cells in culture 2. The results of this particular whole blood assay demonstrate a novel technique useful in elucidating patient cohorts presenting with autoinflammatory pathophysiologies.

Accurate and Simple Measurement of the Pro-inflammatory Cytokine IL-1&amp;#946; using a Whole Blood Stimulation Assay

We describe a simple immunoassay to measure the production of pro-inflammatory cytokines, such as IL-1 beta production, in patients presenting with autoinflammatory phenotypes. By activating cells in whole blood cultures with pathogen-associated molecular patterns, specifically with lipopolysaccharide, cytokine secretion can be conveniently evaluated in whole blood supernatants.

Inflammatory processes resulting from the secretion of soluble mediators by immune cells, lead to various manifestations in skin, joints and other tissues ...

A Simplified Technique for Producing an Ischemic Wound Model

One major obstacle in current diabetic wound research is a lack of an ischemic wound model that can be safely used in diabetic animals. Drugs that work well in non-ischemic wounds may not work in human diabetic wounds because vasculopathy is one major factor that hinders healing of these wounds. We published an article in 2007 describing a rabbit ear ischemic wound model created by a minimally invasive surgical technique. Since then, we have further simplified the procedure for easier operation. On one ear, three small skin incisions were made on the vascular pedicles, 1-2 cm from the ear base. The central artery was ligated and cut along with the nerve. The whole cranial bundle was cut and ligated, leaving only the caudal branch intact. A circumferential subcutaneous tunnel was made through the incisions, to cut subcutaneous tissues, muscles, nerves, and small vessels. The other ear was used as a non-ischemic control. Four wounds were made on the ventral side of each ear. This technique produces 4 ischemic wounds and 4 non-ischemic wounds in one animal for paired comparisons. After surgery, the ischemic ear was cool and cyanotic, and showed reduced movement and a lack of pulse in the ear artery. Skin temperature of the ischemic ear was 1-10 &deg;C lower than that on the normal ear and this difference was maintained for more than one month. Ear tissue high-energy phosphate contents were lower in the ischemic ear than the control ear. Wound healing times were longer in the ischemic ear than in the non-ischemic ear when the same treatment was used. The technique has now been used on more than 80 rabbits in which 23 were diabetic (diabetes time ranging from 2 weeks to 2 years). No single rabbit has developed any surgical complications such as bleeding, infection, or rupture in the skin incisions. The model has many advantages, such as little skin disruption, longer ischemic time, and higher success rate, when compared to many other models. It can be safely used in animals with reduced resistance, and can also be modified to meet different testing requirements.

We have developed a minimally invasive technique to create a rabbit ischemic ear wound model by dividing the central artery and nerve and the cranial neurovascular bundle. A subcutaneous tunnel then cuts all subcutaneous tissues. This procedure causes minimal skin disruption and can be safely used in diabetic animals.

One major obstacle in current diabetic wound research is a lack of an ischemic wound model that can be safely used in diabetic animals. Drugs that work ...

Endothelin-1 Induced Middle Cerebral Artery Occlusion Model for Ischemic Stroke with Laser Doppler Flowmetry Guidance in Rat

Stroke is the number one cause of disability and third leading cause of death in the world, costing an estimated $70 billion in the United States in 20091, 2. Several models of cerebral ischemia have been developed to mimic the human condition of stroke. It has been suggested that up to 80% of all strokes result from ischemic damage in the middle cerebral artery (MCA) area3. In the early 1990s, endothelin-1 (ET-1) 4 was used to induce ischemia by applying it directly adjacent to the surface of the MCA after craniotomy. Later, this model was modified 5 by using a stereotaxic injection of ET-1 adjacent to the MCA to produce focal cerebral ischemia. The main advantages of this model include the ability to perform the procedure quickly, the ability to control artery constriction by altering the dose of ET-1 delivered, no need to manipulate the extracranial vessels supplying blood to the brain as well as gradual reperfusion rates that more closely mimics the reperfusion in humans5-7. On the other hand, the ET-1 model has disadvantages that include the need for a craniotomy, as well as higher variability in stroke volume8. This variability can be reduced with the use of laser Doppler flowmetry (LDF) to verify cerebral ischemia during ET-1 infusion. Factors that affect stroke variability include precision of infusion and the batch of the ET-1 used6. Another important consideration is that although reperfusion is a common occurrence in human stroke, the duration of occlusion for ET-1 induced MCAO may not closely mimic that of human stroke where many patients have partial reperfusion over a period of hours to days following occlusion9, 10. This protocol will describe in detail the ET-1 induced MCAO model for ischemic stroke in rats. It will also draw attention to special considerations and potential drawbacks throughout the procedure.

Several animal models of cerebral ischemia have been developed to simulate the human condition of stroke. This protocol describes the endothelin-1 (ET-1) induced middle cerebral artery occlusion (MCAO) model for ischemic stroke in rats. In addition, important considerations, advantages, and shortcomings of this model are discussed.

Stroke is the number one cause of disability and third leading cause of death in the world, costing an estimated $70 billion in the United States in ...

Angiogenesis in the Ischemic Rat Lung

The adult lung is perfused by both the systemic bronchial artery and the entire venous return flowing through the pulmonary arteries. In most lung pathologies, it is the smaller systemic vasculature that responds to a need for enhanced lung perfusion and shows robust neovascularization. Pulmonary vascular ischemia induced by pulmonary artery obstruction has been shown to result in rapid systemic arterial angiogenesis in man as well as in several animal models. Although the histologic assessment of the time course of bronchial artery proliferation in rats was carefully described by Weibel 1, mechanisms responsible for this organized growth of new vessels are not clear. We provide surgical details of inducing left pulmonary artery ischemia in the rat that leads to bronchial neovascularization. Quantification of the extent of angiogenesis presents an additional challenge due to the presence of the two vascular beds within the lung. Methods to determine functional angiogenesis based on labeled microsphere injections are provided.

The lung is perfused by both the systemic bronchial artery and pulmonary arteries. In most lung pathologies, it is the smaller systemic vasculature that shows robust neovascularization. Cessation of pulmonary blood flow promotes brisk bronchial angiogenesis. We provide surgical details of inducing left pulmonary artery ischemia that promotes bronchial neovascularization.

The  adult lung is perfused by both the systemic bronchial artery and the entire  venous return flowing through the pulmonary arteries. In most lung ...

Murine Model of Wound Healing

Wound healing and repair are the most complex biological processes that occur in human life. After injury, multiple biological pathways become activated. Impaired wound healing, which occurs in diabetic patients for example, can lead to severe unfavorable outcomes such as amputation. There is, therefore, an increasing impetus to develop novel agents that promote wound repair. The testing of these has been limited to large animal models such as swine, which are often impractical. Mice represent the ideal preclinical model, as they are economical and amenable to genetic manipulation, which allows for mechanistic investigation. However, wound healing in a mouse is fundamentally different to that of humans as it primarily occurs via contraction. Our murine model overcomes this by incorporating a splint around the wound. By splinting the wound, the repair process is then dependent on epithelialization, cellular proliferation and angiogenesis, which closely mirror the biological processes of human wound healing. Whilst requiring consistency and care, this murine model does not involve complicated surgical techniques and allows for the robust testing of promising agents that may, for example, promote angiogenesis or inhibit inflammation. Furthermore, each mouse acts as its own control as two wounds are prepared, enabling the application of both the test compound and the vehicle control on the same animal. In conclusion, we demonstrate a practical, easy-to-learn, and robust model of wound healing, which is comparable to that of humans.

A murine model of cutaneous wound healing that can be used to assess therapeutic compounds in physiological and pathophysiological settings.

Wound healing and repair are the most complex biological processes that occur in human life. After injury, multiple biological pathways become activated. ...

Ischemic Tissue Injury in the Dorsal Skinfold Chamber of the Mouse: A Skin Flap Model to Investigate Acute Persistent Ischemia

Despite profound expertise and advanced surgical techniques, ischemia-induced complications ranging from wound breakdown to extensive tissue necrosis are still occurring, particularly in reconstructive flap surgery. Multiple experimental flap models have been developed to analyze underlying causes and mechanisms and to investigate treatment strategies to prevent ischemic complications. The limiting factor of most models is the lacking possibility to directly and repetitively visualize microvascular architecture and hemodynamics. The goal of the protocol was to present a well-established mouse model affiliating these before mentioned lacking elements. Harder et al. have developed a model of a musculocutaneous flap with a random perfusion pattern that undergoes acute persistent ischemia and results in ~50% necrosis after 10 days if kept untreated. With the aid of intravital epi-fluorescence microscopy, this chamber model allows repetitive visualization of morphology and hemodynamics in different regions of interest over time. Associated processes such as apoptosis, inflammation, microvascular leakage and angiogenesis can be investigated and correlated to immunohistochemical and molecular protein assays. To date, the model has proven feasibility and reproducibility in several published experimental studies investigating the effect of pre-, peri- and postconditioning of ischemically challenged tissue.

The window of the murine dorsal skinfold chamber presented visualizes a zone of acute persistent ischemia of a musculocutaneous flap. Intravital epi-fluorescence microscopy permits for direct and repetitive assessment of the microvasculature and quantification of hemodynamics. Morphologic and hemodynamic results can further be correlated with histological and molecular analyses.

Despite profound expertise and advanced surgical techniques, ischemia-induced complications ranging from wound breakdown to extensive tissue necrosis are ...

A Mouse Fetal Skin Model of Scarless Wound Repair

Early in utero, but not in postnatal life, cutaneous wounds undergo regeneration and heal without formation of a scar. Scarless fetal wound healing occurs across species but is age dependent. The transition from a scarless to scarring phenotype occurs in the third trimester of pregnancy in humans and around embryonic day 18 (E18) in mice. However, this varies with the size of the wound with larger defects generating a scar at an earlier gestational age. The emergence of lineage tracing and other genetic tools in the mouse has opened promising new avenues for investigation of fetal scarless wound healing. However, given the inherently high rates of morbidity and premature uterine contraction associated with fetal surgery, investigations of fetal scarless wound healing in vivo require a precise and reproducible surgical model. Here we detail a reliable model of fetal scarless wound healing in the dorsum of E16.5 (scarless) and E18.5 (scarring) mouse embryos.

During mammalian development, early gestational skin wounds heal without a scar. Here we detail a reliable and reproducible model of fetal scarless wound healing in the cutaneous dorsum of E16.5 (scarless) and E18.5 (scarring) mouse embryos.

Early in utero, but not in postnatal life, cutaneous wounds undergo regeneration and heal without formation of a scar. Scarless fetal wound healing occurs ...

Rat Model of Photochemically-Induced Posterior Ischemic Optic Neuropathy

Posterior Ischemic optic neuropathy (PION) is a sight-devastating disease in clinical practice. However, its pathogenesis and natural history have&#160;remained poorly understood. Recently, we developed a reliable, reproducible animal model of PION and tested the treatment effect of some neurotrophic factors in this model1. The purpose of this video is to demonstrate our photochemically induced model of posterior ischemic optic neuropathy, and to evaluate its effects with retrograde labeling of retinal ganglion cells. Following surgical exposure of the posterior optic nerve, a photosensitizing dye, erythrosin B, is intravenously injected and a laser beam is focused onto the optic nerve surface. Photochemical interaction of erythrosin B and the laser during irradiation damages the vascular endothelium, prompting microvascular occlusion mediated by platelet thrombosis and edematous compression. The resulting ischemic injury yields a gradual but pronounced retinal ganglion cell dieback, owing to a loss of axonal input - a remote, injury-induced and clinically relevant outcome. Thus, this model provides a novel platform to study the pathophysiologic course of PION,&#160;and can be further optimized for testing therapeutic approaches for optic neuropathies as well as other CNS ischemic diseases.

The goal of this protocol is to photochemically induce ischemic injury to the posterior optic nerve in rat. This model is critical to studies of the pathophysiology of posterior ischemic optic neuropathy, and therapeutic approaches for this and other optic neuropathies, as well as of other CNS ischemic diseases.

Posterior Ischemic optic neuropathy (PION) is a sight-devastating disease in clinical practice. However, its pathogenesis and natural history ...

A Piglet Model of Neonatal Hypoxic-Ischemic Encephalopathy

Birth asphyxia, which causes hypoxic-ischemic encephalopathy (HIE), accounts for 0.66 million deaths worldwide each year, about a quarter of the world&#8217;s 2.9 million neonatal deaths. Animal models of HIE have contributed to the understanding of the pathophysiology in HIE, and have highlighted the dynamic process that occur in brain injury due to perinatal asphyxia. Thus, animal studies have suggested a time-window for post-insult treatment strategies. Hypothermia has been tested as a treatment for HIE in pdiglet models and subsequently proven effective in clinical trials. Variations of the model have been applied in the study of adjunctive neuroprotective methods and piglet studies of xenon and melatonin have led to clinical phase I and II trials1,2. The piglet HIE model is further used for neonatal resuscitation- and hemodynamic studies as well as in investigations of cerebral hypoxia on a cellular level. However, it is a technically challenging model and variations in the protocol may result in either too mild or too severe brain injury. In this article, we demonstrate the technical procedures necessary for establishing a stable piglet model of neonatal HIE. First, the newborn piglet (&#60; 24 hr old, median weight 1500 g) is anesthetized, intubated, and monitored in a setup comparable to that found in a neonatal intensive care unit. Global hypoxia-ischemia is induced by lowering the inspiratory oxygen fraction to achieve global hypoxia, ischemia through hypotension and a flat trace amplitude integrated EEG (aEEG) indicative of cerebral hypoxia. Survival is promoted by adjusting oxygenation according to the aEEG response and blood pressure. Brain injury is quantified by histopathology and magnetic resonance imaging after 72 hr.

Hypoxic-ischemic encephalopathy following perinatal asphyxia can be studied using animal models. We demonstrate the procedures necessary for establishing a piglet model of neonatal hypoxic-ischemic encephalopathy.

Birth asphyxia, which causes hypoxic-ischemic encephalopathy (HIE), accounts for 0.66 million deaths worldwide each year, about a quarter of the ...

The Rodent Model of Nonarteritic Anterior Ischemic Optic Neuropathy (rNAION)

Nonarteritic anterior ischemic optic neuropathy (NAION) is a focal ischemic lesion of the optic nerve that affects 1/700 individuals throughout their lifetime. NAION results in optic nerve edema, selective loss of the retinal ganglion cell neurons (RGCs) and atrophy of the optic nerve. A rodent model of NAION that expresses most NAION features and sequelae has been developed, which is applicable to both rats and mice. This model utilizes a focal laser application of 532 nm wavelength to illuminate a photoactive dye, Rose Bengal (RB), to cause capillary damage and leakage at the targeted anterior optic nerve (the laminar region). After rNAION induction, there is an early optic nerve ischemia, optic nerve edema, and intraneural inflammation, followed by selective RGC and axonal loss. Since the optic nerve is a CNS white matter tract, the rNAION model is applicable to mechanistic studies of selective white matter ischemia, as well as neuroprotective analyses and short and long-term mechanisms of glial and neuronal response to ischemia.

The Rodent Model of Nonarteritic Anterior Ischemic Optic Neuropathy rNAION

The following report describes how to replicate the rodent model of nonarteritic anterior ischemic optic neuropathy (rNAION), using the appropriate dye, contact lens and laser parameters. We also reveal the appropriate steps for evaluating the rNAION lesion in vivo.

Nonarteritic anterior ischemic optic neuropathy (NAION) is a focal ischemic lesion of the optic nerve that affects 1/700 individuals throughout their ...