This works was supported by funding from a Florida Health grant (Brain and spinal cord injury research fund) (KKW).

All procedures were performed under protocols #201207692 approved by the Institutional Animal Care and Use Committee of University of Florida and in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals.
1. Animal Care
<ol>
	<li>Use 3&#8211;4-month-old male C57BL/6J mice. Provide bedding, nesting material, food, and water ad libitum. Keep the mice in ambient temperatures controlled at 20 - 22 &#176;C with constant 12-hr light/12-hr dark cycles.</li>
</ol>
2. Pre-impaction Preparation
<ol>
	<li>Attach a custom-made silicone rubber-coated metal tip to an electromagnetic stereotaxic impact device. Make sure the flat bottom of the tip is parallel to the surface of the probe tip (Figure 1A).</li>
	<li>Anesthetize the mouse with 4% isoflurane followed by maintenance anesthesia of 2.5% isoflurane. Check the anesthesia via the flow meter. Monitor the anesthesia level until the animal reaches a surgical level of anesthesia by showing loss of pedal withdrawal reflex.</li>
	<li>Put the mouse in a prone position on a heating pad. Use a funnel-shaped nose cone to keep the mouse under anesthesia. Completely shave the head using a trimmer. Use petrolatum ophthalmic ointment on the mouse&#39;s eyes to prevent dryness while under anesthesia.</li>
</ol>
3. Impact Parameters Setting
NOTE: The impact system includes a control box to set impact parameters, an actuator to perform the impaction, and a digital stereotactic frame with 3-movement axes.

<ol>
	<li>Pre-set the velocity of the impact device to 4 m/sec and dwell time to 240 msec on the control box.</li>
</ol>
4. Positioning the Impact Center
<ol>
	<li>Put a soft heating pad under the animal&#39;s body to keep the body temperature near 39 &#176;C. Mount the mouse in a stereotactic frame in a prone position with the blunt-end ear bars.</li>
	<li>Lower the impact tip close to the mouse&#39;s head by moving the Z-driver. Adjust the flat impact tip (9 mm diameter) by moving the X- and Y-drivers midway to the target coordinates above the sagittal suture.</li>
	<li>Make sure one edge of the impact tip is vertically parallel to an imaginary horizontal line drawn between the two ears (Figure 1C). The center of impact corresponds to the central sagittal suture midway between interfrontal and lambdoid sutures (interaural 9 mm to interaural 0 mm, lateral 4.5 mm).</li>
</ol>
5. Impact Depth Setting
<ol>
	<li>To correctly set the impact depth, use additional probe tip to replace the insulated silicone rubber-coated impact tip.</li>
	<li>To make sure there is no shift of the impact center after switching tips, set the X and Y channel on the digital stereotaxic control panel to zero before switching the tips.</li>
	<li>Move the probe tip to the center of the impact area by manually moving the X-and Y-drives.</li>
	<li>Clip contact sensor to the mouse&#39;s tail.</li>
	<li>Move the impactor (Z drive) down until the probe tip touches the surface of the impact site.</li>
	<li>Set the Z channel on the stereotaxic control panel to zero.</li>
	<li>Move the impact tip back to the impact area by manually adjusting X- and Y-drivers (NOT the zero buttons on the digital stereotaxic control panel) until X- and Y-drivers are zero (where the impact tip was previously positioned).</li>
	<li>Retract the actuator by moving the retract switch on the control box. Manually move the impactor down (Z driver) by 4 mm.</li>
</ol>
6. Impact
<ol>
	<li>Trigger the impact by clicking the impact switch on the control box and achieve a deformation depth of 4 mm.</li>
</ol>
7. Post-impaction
<ol>
	<li>Measure the time from the impact until the mouse&#39;s first breath using a timer.</li>
	<li>Remove the animal from the instrument and place them on a warm pad to maintain their body temperature. Do not leave the animal unattended until it has regained sufficient consciousness to maintain sternal recumbency.</li>
	<li>Allow for recovery before returning the animal back into a clean cage. Do not return an animal to the company of other animals until fully recovered.</li>
	<li>Observe and weigh the mice daily. If the mice show signs of pain, intraperitoneally inject them with Meloxicam at 1 - 2 mg/kg every 12 - 24 hr.</li>
</ol>
8. Repetitive Impaction
<ol>
	<li>Give the mice additional injuries on days 4, 7, and 10 after the initial injury (72 hr interval between impacts).</li>
</ol>
9. Immunohistochemistry (IHC)
<ol>
	<li>Transcardial perfusion
	<ol>
		<li>Anesthetize the mice via intraperitoneal injection with 200 m/kg pentobarbital.</li>
		<li>Assess and assure surgical-plane anesthesia by a toe pinch. Secure the mouse in the supine position by gently taping the forepaws and hind paws to a Styrofoam work surface inside a chemical fume hood.</li>
		<li>Make an incision through the skin along the thoracic midline from just beneath the xiphoid process to the clavicle. Make two additional skin incisions at the xiphoid process and proceed along the base of the ventral ribcage laterally.</li>
		<li>Open the thoracic cavity and expose the heart by cutting through the thoracic musculature and ribcage.</li>
		<li>Secure the beating heart with blunt forceps and make a 1 - 2 mm incision in the left ventricle.</li>
		<li>Immediately insert a butterfly needle into the right atrium. Begin the infusion of 20ml saline by pushing the syringe slowly.</li>
		<li>Switch from saline to 4% paraformaldehyde. Continue perfusion with 20ml of paraformaldehyde.</li>
		<li>Decapitate the mouse and remove the skin with scissors. Isolate the brain from the skull using a bone cutter.</li>
	</ol>
	</li>
	<li>Cryostat sectioning
	<ol>
		<li>Embed brain tissues in optimum cutting temperature (O.C.T.) formulation and freeze at -80 &#176;C. Place the brain in the cryostat in a sagittal orientation. Cut brain sections 5 &#181;m thick.</li>
	</ol>
	</li>
	<li>Staining
	<ol>
		<li>Dry the frozen sections at room temperature for 1 hr.</li>
		<li>Incubate the slides with 100 &#956;l of 2% goat serum and 0.1% Triton X-100 in phosphate buffered saline (PBS) for 1 hr at RT.</li>
		<li>Wash the slides 3 times with 300 &#956;l of PBS. Then incubate the slides with anti-GFAP (1:200) or anti-ferritin antibody (1:200) separately over night at 4 &#176;C.</li>
		<li>Wash the slides 3 times with 300 &#956;l of PBS. Then incubate the slides for 2 hr at room temperature with biotin-conjugated secondary antibody.</li>
		<li>Wash the slides 3 times with 300 &#956;l of PBS. Then incubate the slides with avidin-biotin complex (ABC) solution (1:50) at room temperature for 30 min.</li>
		<li>Wash the slides 3 times with 300 &#956;l of PBS. Then incubate in 3,3&#8242;-diaminobenzidine (DAB) substrate solution (50 ml PBS, 10 &#181;l H2O2, 10 mg DAB pill, filter before using) for 5 - 8 min. Observe the slides under the microscope until the positive cells appear.</li>
		<li>Rinse the slides in slow running tap water for 5 min. Clean slides with a lab-wipe. Then mount the sections with mounting medium and coverslip.</li>
	</ol>
	</li>
</ol>

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	<li>Baugh, C. 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=Chronic+traumatic+encephalopathy:+neurodegeneration+following+repetitive+concussive+and+subconcussive+brain+trauma.">Chronic traumatic encephalopathy: neurodegeneration following repetitive concussive and subconcussive brain trauma.</a> Brain Imaging Behav. 6 (2), 244-254 (2012).</li><li>McKee, A. 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=Chronic+traumatic+encephalopathy+in+athletes:+progressive+tauopathy+after+repetitive+head+injury.">Chronic traumatic encephalopathy in athletes: progressive tauopathy after repetitive head injury.</a> J. Neuropathol Exp Neurol. 68 (7), 709-735 (2009).</li><li>Petraglia, A. L., Dashnaw, M. L., Turner, R. C., Bailes, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Models+of+mild+traumatic+brain+injury:+translation+of+physiological+and+anatomic+injury.">Models of mild traumatic brain injury: translation of physiological and anatomic injury.</a> Neurosurgery. 75 Suppl (4), S34-S49 (2014).</li><li>Goldstein, L. E., McKee, A. C., Stanton, P. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Considerations+for+animal+models+of+blast-related+traumatic+brain+injury+and+chronic+traumatic+encephalopathy.">Considerations for animal models of blast-related traumatic brain injury and chronic traumatic encephalopathy.</a> Alzheimers Res Ther. 6 (5), 64 (2014).</li><li>Gold, 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=Functional+assessment+of+long-term+deficits+in+rodent+models+of+traumatic+brain+injury.">Functional assessment of long-term deficits in rodent models of traumatic brain injury.</a> RegenMed. 8 (4), 483-516 (2013).</li><li>Xiong, Y., Mahmood, A., Chopp, 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+of+traumatic+brain+injury.">Animal models of traumatic brain injury.</a> Nat Rev Neurosci. 14 (2), 128-142 (2013).</li><li>Luo, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Long-term+cognitive+impairments+and+pathological+alterations+in+a+mouse+model+of+repetitive+mild+traumatic+brain+injury.">Long-term cognitive impairments and pathological alterations in a mouse model of repetitive mild traumatic brain injury.</a> Front Neurol. , 5-12 (2014).</li><li>Yang, Z., 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=Temporal+MRI+characterization,+neurobiochemical+and+neurobehavioral+changes+in+a+mouse+repetitive+concussive+head+injury+model.">Temporal MRI characterization, neurobiochemical and neurobehavioral changes in a mouse repetitive concussive head injury model.</a> Sci Rep. 10 (5), 11178 (2015).</li><li>Zhang, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inhibition+of+monoacylglycerol+lipase+prevents+chronic+traumatic+encephalopathy-like+neuropathology+in+a+mouse+model+of+repetitive+mild+closed+head+injury.">Inhibition of monoacylglycerol lipase prevents chronic traumatic encephalopathy-like neuropathology in a mouse model of repetitive mild closed head injury.</a> J Cereb Blood Flow Metab. 35 (3), 443-453 (2015).</li><li>Petraglia, A. 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The authors have no financial interest to disclose.

To mimic brain injuries morphologically similar to the clinical condition, post-concussion symptoms are expected. Post-concussion symptoms generally include headaches, dizziness, vertigo, fatigue, memory and sleeping problems, trouble concentrating as well as anxiety, and depressed mood. Since somatic symptoms may not yet be measurable in animal models, the changes of motor and cognitive function and emotional behavior are used as criteria for rationally evaluating concussion in animal models. In a previous reported stud...

Concussion, also called mild traumatic brain injury (mTBI), is the most frequent occurrence of traumatic brain injury (TBI) and affects millions of people in United States. Concussions can be tricky to diagnose and there is no specific cure for concussion. There is a growing recognition and some evidence that mild mechanical trauma resulting from sports injuries, military combat, and other physically engaging pursuits may have cumulative and chronic neurological consequences1,2. However, there is still a lack of knowledge regarding concussions and their effects. Current methodology restricts the studies of pathology and treatment in humans since only neurologic assessment and imaging evaluation are available for clinical diagnosis. Animal models provide a means to study concussions in an efficient, rigorous, and controlled manner with the hope of further diagnosis and treatment of mTBI.
Studies have adapted traditional TBI models such as controlled cortical impact (CCI), fluid-percussion impact (FPI), weight drop injury, and blast injury to perform mTBI and stimulate low injury severities by changing the injury parameters. These models are beneficial to use due to their ability to replicate brain trauma morphologically similar to the clinical condition; however, they also have their own limitations. The severity of injury induced by an acceleration injury (weight drop) is often highly variable. The two results of the mild CCI &#8212; subarachnoid hemorrhage and focal contusion &#8212; are not comparable with typical human concussions. CCI and FPI require a craniotomy, which is not clinically relevant, while blast injury is a more controversial model in regards to the different exposure position and peak pressure measurements as well as variable secondary injury during the exposure3-6. An updated concussive animal model that can translate pre-clinical research into the clinical setting is necessary in research.
The key issue in modeling mild TBI is to define the experimental injury severity, which most closely replicates the injury in a clinical setting. Recently, different research groups developed the closed head injury or concussive head injury (CHI) model7-10. CHI is a modification of CCI without a craniotomy, but it still uses a traditional electronic magnetic impact system to generate a head impact. A CHI can induce a concussion ranging from mild to moderate by adjusting the impact parameters. Loss of consciousness (LOC) can be observed immediately after an impact by detecting a decrease in the breathing rate or the transient termination of breathing. The period of LOC is used to determine the severity of injury. This paper includes a slightly improved and updated version of a repetitive CHI (rCHI) model in mice, along with a detailed step-by-step protocol and representative results. The rCHI model research strategies are beneficial in determining mTBI effects and potential treatments, especially since there is no individual animal model capable of imitating all of the concussion-induced pathological changes.

<table border="0" cellpadding="0" cellspacing="0" width="831">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">anesthesia machine</td>
			<td style="width:188px;">Eagle Eye Anesthesia, Inc</td>
			<td style="width:137px;">Model 150&#160;</td>
			<td style="width:291px;">anesthesia</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Electromagnetic Impactor</td>
			<td style="width:188px;">LeicaBiosystems</td>
			<td style="width:137px;">Impact One Stereotaxic Impactor</td>
			<td>perform impaction</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Digital Stereotaxic instrument</td>
			<td style="width:188px;">LeicaBiosystems</td>
			<td style="width:137px;">39462501</td>
			<td>mount mouse and positioning tips</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Sicilone rubber-coated metal tip</td>
			<td style="width:188px;">Precision Tool &#38; Engineering, Gainesvill FL</td>
			<td style="width:137px;">custom-made</td>
			<td>impact tip</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Lithium Ion All-in-One Trimmer</td>
			<td style="width:188px;">WAHL Home Products</td>
			<td style="width:137px;">9854-600</td>
			<td>shave mouse hair</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:216px;">paper clips</td>
			<td style="width:188px;">custom-made</td>
			<td style="width:137px;"></td>
			<td>probe tip</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Cotton tipped applicators</td>
			<td style="width:188px;">MEDLINE</td>
			<td style="width:137px;">MDS202055</td>
			<td>scrub head with saline</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tissue Tek O.C.T.</td>
			<td style="width:188px;">ASKURA FINETEK USA INC</td>
			<td style="width:137px;">4583</td>
			<td>tissue embedding</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">anti-GFAP</td>
			<td style="width:188px;">Dako</td>
			<td style="width:137px;">CA93013</td>
			<td>antibody for IHC</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">anti Ferritin</td>
			<td style="width:188px;">Sigma</td>
			<td style="width:137px;">F6136</td>
			<td>antibody for IHC</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">VECTASTAIN Elite ABC&#160; kit</td>
			<td style="width:188px;">Vector laboratories</td>
			<td style="width:137px;">PK-6100</td>
			<td>IHC detection system</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Permount Mounting Medium</td>
			<td style="width:188px;">Fisher Scientific</td>
			<td style="width:137px;">SP15-100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Aperio XT ScanScope scanner</td>
			<td style="width:188px;">Leica Microsystems Inc,</td>
			<td style="width:137px;"></td>
			<td>slides scanning</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Leica AutoStainer XL</td>
			<td style="width:188px;">Leica the pathology Company</td>
			<td style="width:137px;">ST2010</td>
			<td>H&#38;E staining</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">DAB&#160;</td>
			<td style="width:188px;">sigma</td>
			<td style="width:137px;">D3939</td>
			<td>IHC detection system</td>
		</tr>
	</tbody>
</table>

a repetitive concussive head injury model in mice

Despite the concussion/ mild traumatic brain injury (mTBI) being the most frequent occurrence of traumatic brain injury, there is still a lack of knowledge on the injury and its effects. To develop a better understanding of concussions, animals are often used because they provide a controlled, rigorous, and efficient model. Studies have adapted traditional animal models to perform mTBI to stimulate mild injury severity by changing the injury parameters. These models have been used because they can produce morphologically similar brain injuries to the clinical condition and provide a spectrum of injury severities. However, they are limited in their ability to present the identical features of injuries in patients. Using a traditional impact system, a repetitive concussive injury (rCHI) model can induce mild to moderate human-like concussion. The injury degree can be determined by measuring the period of loss of consciousness (LOC) with a sign of a transient termination of breathing. The rCHI model is beneficial to use for its accuracy and simplicity in determining mTBI effects and potential treatments.

In this model (Figure 1 A-C), there were brief periods of gasping and shallow respirations. A loss of consciousness (unconscious) is defined as a decrease in the breathing rate or transient termination of breathing before resuming a normal respiration. An impact on the center of the head caused short-term unconsciousness (7.5 &#177; 4.7, 7.8 &#177; 5.5, 10.2 &#177; 8.8, 9.5 &#177; 8.0 sec at each impact separately, Figure 1D). Mouse brains showed normal m...

Watch this Scientific Journal Video about A Repetitive Concussive Head Injury Model in Mice at JoVE.com

A Repetitive Concussive Head Injury Model in Mice

Concussion presents the most common type of traumatic brain injury. Therefore, a repetitive concussive animal model, which replicates the important features of an injury in patients, may provide a means to study concussion in a rigorous, controlled, and efficient manner.

Despite the concussion/ mild traumatic brain injury (mTBI) being the most frequent occurrence of traumatic brain injury, there is still a lack of ...

a-repetitive-concussive-head-injury-model-in-mice

Research

JoVE Journal

Medicine

11.8K Views.  University of Florida. Concussion presents the most common type of traumatic brain injury. Therefore, a repetitive concussive animal model, which replicates the important features of an injury in patients, may provide a means to study concussion in a rigorous, controlled, and efficient manner.

Video: A Repetitive Concussive Head Injury Model in Mice

The Spared Nerve Injury (SNI) Model of Induced Mechanical Allodynia in Mice

Peripheral neuropathic pain is a severe chronic pain condition which may result from trauma to sensory nerves in the peripheral nervous system. The spared nerve injury (SNI) model induces symptoms of neuropathic pain such as mechanical allodynia i.e. pain due to tactile stimuli that do not normally provoke a painful response [1]. 
The SNI mouse model involves ligation of two of the three branches of the sciatic nerve (the tibial nerve and the common peroneal nerve), while the sural nerve is left intact [2]. The lesion results in marked hypersensitivity in the lateral area of the paw, which is innervated by the spared sural nerve. The non-operated side of the mouse can be used as a control. The advantages of the SNI model are the robustness of the response and that it doesn&#x2019;t require expert microsurgical skills.
The threshold for mechanical pain response is determined by testing with von Frey filaments of increasing bending force, which are repetitively pressed against the lateral area of the paw [3], [4]. A positive pain reaction is defined as sudden paw withdrawal, flinching and/or paw licking induced by the filament. A positive response in three out of five repetitive stimuli is defined as the pain threshold. 
As demonstrated in the video protocol, C57BL/6 mice experience profound allodynia as early as the day following surgery and maintain this for several weeks.

The Spared Nerve Injury SNI Model of Induced Mechanical Allodynia in Mice

The Spared Nerve Injury animal model is described here as a mouse model of peripheral neuropathic pain following partial denervation of the sciatic nerve by lesioning the tibial and common peroneal nerve branches, leaving the remaining sural nerve intact. Behavioral modification resulting from mechanical allodynia is quantified by von Frey filaments.

Peripheral neuropathic pain is a severe chronic pain condition which may result from trauma to sensory nerves in the peripheral nervous system. The spared ...

Controlled Cervical Laceration Injury in Mice

Use of genetically modified mice enhances our understanding of molecular mechanisms underlying several neurological disorders such as a spinal cord injury (SCI). Freehand manual control used to produce a laceration model of SCI creates inconsistent injuries often associated with a crush or contusion component and, therefore, a novel technique was developed. Our model of cervical laceration SCI has resolved inherent difficulties with the freehand method by incorporating 1) cervical vertebral stabilization by vertebral facet fixation, 2) enhanced spinal cord exposure, and 3) creation of a reproducible laceration of the spinal cord using an oscillating blade with an accuracy of &plusmn;0.01 mm in depth without associated contusion. Compared to the standard methods of creating a SCI laceration such as freehand use of a scalpel or scissors, our method has produced a consistent lesion. This method is useful for studies on axonal regeneration of corticospinal, rubrospinal, and dorsal ascending tracts.

A novel technique to create a reproducible in vivo model of cervical spinal cord laceration injury in the mouse is described. This technique is based on spine stabilization by fixation of the cervical facets and laceration of the spinal cord using an oscillating blade with an accuracy of &plusmn;0.01 mm.

Use of genetically modified mice enhances our  understanding of molecular mechanisms underlying several neurological disorders  such as a spinal cord ...

A Contusion Model of Severe Spinal Cord Injury in Rats

The translational potential of novel treatments should be investigated in severe spinal cord injury (SCI) contusion models. A detailed methodology is described to obtain a consistent model of severe SCI. Use of a stereotactic frame and computer controlled impactor allows for creation of reproducible injury. Hypothermia and urinary tract infection pose significant challenges in the post-operative period. Careful monitoring of animals with daily weight recording and bladder expression allows for early detection of post-operative complications. The functional results of this contusion model are equivalent to transection models. The contusion model can be utilized to evaluate the efficacy of both neuroprotective and neuroregenerative approaches.

A contusion model of severe spinal cord injury is described. Detailed pre-operative, operative and post-operative steps are described to obtain a consistent model.

The translational potential of novel treatments should be investigated in severe spinal cord injury (SCI) contusion models. A detailed methodology is ...

Ischemia-reperfusion Model of Acute Kidney Injury and Post Injury Fibrosis in Mice

Ischemia-reperfusion induced acute kidney injury (IR-AKI) is widely used as a model of AKI in mice, but results are often quite variable with high, often unreported mortality rates that may confound analyses. Bilateral renal pedicle clamping is commonly used to induce IR-AKI, but differences between effective clamp pressures and/or renal responses to ischemia between kidneys often lead to more variable results. In addition, shorter clamp times are known to induce more variable tubular injury, and while mice undergoing bilateral injury with longer clamp times develop more consistent tubular injury, they often die within the first 3 days after injury due to severe renal insufficiency. To improve post-injury survival and obtain more consistent and predictable results, we have developed two models of unilateral ischemia-reperfusion injury followed by contralateral nephrectomy. Both surgeries are performed using a dorsal approach, reducing surgical stress resulting from ventral laparotomy, commonly used for mouse IR-AKI surgeries. For induction of moderate injury BALB/c mice undergo unilateral clamping of the renal pedicle for 26 min and also undergo simultaneous contralateral nephrectomy. Using this approach, 50-60% of mice develop moderate AKI 24 hr after injury but 90-100% of mice survive. To induce more severe AKI, BALB/c mice undergo renal pedicle clamping for 30 min followed by contralateral nephrectomy 8 days after injury. This allows functional assessment of renal recovery after injury with 90-100% survival. Early post-injury tubular damage as well as post injury fibrosis are highly consistent using this model.

We describe models of moderate and severe ischemia-reperfusion-induced kidney injury in which the mice undergo unilateral renal pedicle clamping followed by simultaneous or delayed contralateral nephrectomy, respectively. These models consistently give rise to renal dysfunction and post-injury fibrosis, but injury severity and survival are dependent on mouse background, age and surgical equipment.

Ischemia-reperfusion induced acute kidney injury (IR-AKI) is widely used as a model of AKI in mice, but results are often quite variable with high, often ...

Renal Ischaemia Reperfusion Injury: A Mouse Model of Injury and Regeneration

Renal ischaemia reperfusion injury (IRI) is a common cause of acute kidney injury (AKI) in patients and occlusion of renal blood flow is unavoidable during renal transplantation. Experimental models that accurately and reproducibly recapitulate renal IRI are crucial in dissecting the pathophysiology of AKI and the development of novel therapeutic agents. Presented here is a mouse model of renal IRI that results in reproducible AKI. This is achieved by a midline laparotomy approach for the surgery with one incision allowing both a right nephrectomy that provides control tissue and clamping of the left renal pedicle to induce ischaemia of the left kidney. By careful monitoring of the clamp position and body temperature during the period of ischaemia this model achieves reproducible functional and structural injury. Mice sacrificed 24 hr&#160;following surgery demonstrate loss of renal function with elevation of the serum or plasma creatinine level as well as structural kidney damage with acute tubular necrosis evident. Renal function improves and the acute tissue injury resolves during the course of 7 days following renal IRI such that this model may be used to study renal regeneration. This model of renal IRI has been utilized to study the molecular and cellular pathophysiology of AKI as well as analysis of the subsequent renal regeneration.

The mouse model of renal ischaemia reperfusion injury described here comprises of a right nephrectomy that provides control tissue and clamping of the left renal pedicle to induce ischaemia that results in acute kidney injury. This model uses a midline laparotomy approach with all steps performed via one incision.

Renal ischaemia reperfusion injury (IRI) is a common cause of acute kidney injury (AKI) in patients and occlusion of renal blood flow is unavoidable ...

A Simple Critical-sized Femoral Defect Model in Mice

While bone has a remarkable capacity for regeneration, serious bone trauma often results in damage that does not properly heal. In fact, one tenth of all limb bone fractures fail to heal completely due to the extent of the trauma, disease, or age of the patient. Our ability to improve bone regenerative strategies is critically dependent on the ability to mimic serious bone trauma in test animals, but the generation and stabilization of large bone lesions is technically challenging. In most cases, serious long bone trauma is mimicked experimentally by establishing a defect that will not naturally heal. This is achieved by complete removal of a bone segment that is larger than 1.5 times the diameter of the bone cross-section. The bone is then stabilized with a metal implant to maintain proper orientation of the fracture edges and allow for mobility. 
Due to their small size and the fragility of their long bones, establishment of such lesions in mice are beyond the capabilities of most research groups. As such, long bone defect models are confined to rats and larger animals. Nevertheless, mice afford significant research advantages in that they can be genetically modified and bred as immune-compromised strains that do not reject human cells and tissue.
Herein, we demonstrate a technique that facilitates the generation of a segmental defect in mouse femora using standard laboratory and veterinary equipment. With practice, fabrication of the fixation device and surgical implantation is feasible for the majority of trained veterinarians and animal research personnel. Using example data, we also provide methodologies for the quantitative analysis of bone healing for the model.

Animal models are frequently employed to mimic serious bone injury in biomedical research. Due to their small size, establishment of stabilized bone lesions in mice are beyond the capabilities of most research groups. Herein, we describe a simple method for establishing and analyzing experimental femoral defects in mice.

While bone has a remarkable capacity for regeneration, serious bone trauma often results in damage that does not properly heal. In fact, one tenth of all ...

Facial Nerve Axotomy in Mice: A Model to Study Motoneuron Response to Injury

The goal of this surgical protocol is to expose the facial nerve, which innervates the facial musculature, at its exit from the stylomastoid foramen and either cut or crush it to induce peripheral nerve injury. Advantages of this surgery are its simplicity, high reproducibility, and the lack of effect on vital functions or mobility from the subsequent facial paralysis, thus resulting in a relatively mild surgical outcome compared to other nerve injury models. A major advantage of using a cranial nerve injury model is that the motoneurons reside in a relatively homogenous population in the facial motor nucleus in the pons, simplifying the study of the motoneuron cell bodies. Because of the symmetrical nature of facial nerve innervation and the lack of crosstalk between the facial motor nuclei, the operation can be performed unilaterally with the unaxotomized side serving as a paired internal control. A variety of analyses can be performed postoperatively to assess the physiologic response, details of which are beyond the scope of this article. For example, recovery of muscle function can serve as a behavioral marker for reinnervation, or the motoneurons can be quantified to measure cell survival. Additionally, the motoneurons can be accurately captured using laser microdissection for molecular analysis. Because the facial nerve axotomy is minimally invasive and well tolerated, it can be utilized on a wide variety of genetically modified mice. Also, this surgery model can be used to analyze the effectiveness of peripheral nerve injury treatments. Facial nerve injury provides a means for investigating not only motoneurons, but also the responses of the central and peripheral glial microenvironment, immune system, and target musculature. The facial nerve injury model is a widely accepted peripheral nerve injury model that serves as a powerful tool for studying nerve injury and regeneration.

We present a surgical protocol detailing how to perform a cut or crush axotomy on the facial nerve in the mouse. The facial nerve axotomy can be employed to study the physiological response to nerve injury and test therapeutic techniques.

The goal of this surgical protocol is to expose the facial nerve, which innervates the facial musculature, at its exit from the stylomastoid foramen and ...

Quantification of Neurovascular Protection Following Repetitive Hypoxic Preconditioning and Transient Middle Cerebral Artery Occlusion in Mice

Experimental animal models of stroke are invaluable tools for understanding stroke pathology and developing more effective treatment strategies. A 2 week protocol for repetitive hypoxic preconditioning (RHP) induces long-term protection against central nervous system (CNS) injury in a mouse model of focal ischemic stroke. RHP consists of 9 stochastic exposures to hypoxia that vary in both duration (2 or 4 hr) and intensity (8% and 11% O2). RHP reduces infarct volumes, blood-brain barrier (BBB) disruption, and the post-stroke inflammatory response for weeks following the last exposure to hypoxia, suggesting a long-term induction of an endogenous CNS-protective phenotype. The methodology for the dual quantification of infarct volume and BBB disruption is effective in assessing neurovascular protection in mice with RHP or other putative neuroprotectants. Adult male Swiss Webster mice were preconditioned by RHP or duration-equivalent exposures to 21% O2 (i.e. room air). A 60 min transient middle cerebral artery occlusion (tMCAo) was induced 2 weeks following the last hypoxic exposure. Both the occlusion and reperfusion were confirmed by transcranial laser Doppler flowmetry. Twenty-two hr after reperfusion, Evans Blue (EB) was intravenously administered through a tail vein injection. 2 hr later, animals were sacrificed by isoflurane overdose and brain sections were stained with 2,3,5- triphenyltetrazolium chloride (TTC). Infarcts volumes were then quantified. Next, EB was extracted from the tissue over 48 hr to determine BBB disruption after tMCAo. In summary, RHP is a simple protocol that can be replicated, with minimal cost, to induce long-term endogenous neurovascular protection from stroke injury in mice, with the translational potential for other CNS-based and systemic pro-inflammatory disease states.

This protocol describes repetitive hypoxic preconditioning, or brief exposures to systemic hypoxia that reduce infarct volumes and blood-brain barrier disruption following transient middle cerebral artery occlusion in mice. It also details dual quantification of infarct volume and blood-brain barrier disruption after stroke to assess the efficacy of neurovascular protection.

Experimental animal models of stroke are invaluable tools for understanding stroke pathology and developing more effective treatment strategies. A 2 week ...

Photothrombosis-induced Focal Ischemia as a Model of Spinal Cord Injury in Mice

Spinal cord injury (SCI) is a devastating clinical condition causing permanent changes in sensorimotor and autonomic functions of the spinal cord (SC) below the site of injury. The secondary ischemia that develops following the initial mechanical insult is a serious complication of the SCI and severely impairs the function and viability of surviving neuronal and non-neuronal cells in the SC. In addition, ischemia is also responsible for the growth of lesion during chronic phase of injury and interferes with the cellular repair and healing processes. Thus there is a need to develop a spinal cord ischemia model for studying the mechanisms of ischemia-induced pathology. Focal ischemia induced by photothrombosis (PT) is a minimally invasive and very well established procedure used to investigate the pathology of ischemia-induced cell death in the brain. Here, we describe the use of PT to induce an ischemic lesion in the spinal cord of mice. Following retro-orbital sinus injection of Rose Bengal, the posterior spinal vein and other capillaries on the dorsal surface of SC were irradiated with a green light resulting in the formation of a thrombus and thus ischemia in the affected region. Results from histology and immunochemistry studies show that PT-induced ischemia caused spinal cord infarction, loss of neurons and reactive gliosis. Using this technique a highly reproducible and relatively easy model of SCI in mice can be achieved that would serve the purpose of scientific investigations into the mechanisms of ischemia induced cell death as well as the efficacy of neuroprotective drugs. This model will also allow exploration of the pathological changes that occur following SCI in live mice like axonal degeneration and regeneration, neuronal and astrocytic Ca2+ signaling using two-photon microscopy.

Photothrombosis is a minimally invasive and highly reproducible procedure to induce focal ischemia in the spinal cord and serves as a model of spinal cord injury in mice.

Spinal cord injury (SCI) is a devastating clinical condition causing permanent changes in sensorimotor and autonomic functions of the spinal cord (SC) ...

Induction of Accelerated Atherosclerosis in Mice: The "Wire-Injury" Model

Atherosclerosis is a proliferative fibro-inflammatory disease developing in the arterial wall, inducing a deficient blood flow or a lack of blood flow. Moreover, by rupture of the defective vascular wall, atherosclerosis induces occlusive thrombus formation, which represents the main cause of myocardial infarction or stroke and the most frequent cause of death. Despite the advances in the cardiovascular field, many questions remain unanswered, and additional basic research is essential to improve our understanding of the molecular mechanisms during atherosclerosis and its effects. Due to limited clinical studies, there is a need for representative animal models recreating atherosclerotic conditions such as neointima formation after stent implantation, balloon angioplasty, or endarterectomy. Since the mouse presents many advantages and is the most frequently used model for studying molecular processes, the current study proposes an invasive procedure of endothelial denudation, also known as the wire-injury model, which is representative of the human condition of neointima formation in arteries after revascularization procedures.

This study describes an invasive procedure for the induction of accelerated atherosclerosis in mice. In comparison to other methods using electric- or cryo-induced injury, mechanical-induced injury mimics the human condition of restenosis after revascularization therapies and is ideal for the study of the molecular mechanisms involved.

Atherosclerosis is a proliferative fibro-inflammatory disease developing in the arterial wall, inducing a deficient blood flow or a lack of blood flow. ...