Name: a repetitive concussive head injury model in mice
Uploaded: 2016-10-12T14:00:00.000+00:00
Duration: 5 min 42 s
Description: Watch this Scientific Journal Video about A Repetitive Concussive Head Injury Model in Mice at JoVE.com

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

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Research

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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

Lateral Fluid Percussion: Model of Traumatic Brain Injury in Mice

Traumatic brain injury (TBI) research has attained renewed momentum due to the increasing awareness of head injuries, which result in morbidity and mortality. Based on the nature of primary injury following TBI, complex and heterogeneous secondary consequences result, which are followed by regenerative processes 1,2. Primary injury can be induced by a direct contusion to the brain from skull fracture or from shearing and stretching of tissue causing displacement of brain due to movement 3,4. The resulting hematomas and lacerations cause a vascular response 3,5, and the morphological and functional damage of the white matter leads to diffuse axonal injury 6-8. Additional secondary changes commonly seen in the brain are edema and increased intracranial pressure 9. Following TBI there are microscopic alterations in biochemical and physiological pathways involving the release of excitotoxic neurotransmitters, immune mediators and oxygen radicals 10-12, which ultimately result in long-term neurological disabilities 13,14. Thus choosing appropriate animal models of TBI that present similar cellular and molecular events in human and rodent TBI is critical for studying the mechanisms underlying injury and repair.
Various experimental models of TBI have been developed to reproduce aspects of TBI observed in humans, among them three specific models are widely adapted for rodents: fluid percussion, cortical impact and weight drop/impact acceleration 1. The fluid percussion device produces an injury through a craniectomy by applying a brief fluid pressure pulse on to the intact dura. The pulse is created by a pendulum striking the piston of a reservoir of fluid. The percussion produces brief displacement and deformation of neural tissue 1,15. Conversely, cortical impact injury delivers mechanical energy to the intact dura via a rigid impactor under pneumatic pressure 16,17. The weight drop/impact model is characterized by the fall of a rod with a specific mass on the closed skull 18. Among the TBI models, LFP is the most established and commonly used model to evaluate mixed focal and diffuse brain injury 19. It is reproducible and is standardized to allow for the manipulation of injury parameters. LFP recapitulates injuries observed in humans, thus rendering it clinically relevant, and allows for exploration of novel therapeutics for clinical translation 20.
We describe the detailed protocol to perform LFP procedure in mice. The injury inflicted is mild to moderate, with brain regions such as cortex, hippocampus and corpus callosum being most vulnerable. Hippocampal and motor learning tasks are explored following LFP.

Lateral fluid percussion (LFP), an established model of traumatic brain injury in mice, is demonstrated. LFP fulfills three major criteria for animal models: validity, reliability and clinical relevance. The procedure, consisting of surgical craniotomy, fixation of hub followed by induction of injury, resulting in focal and diffuse injuries, is described.

Traumatic brain injury (TBI) research has attained renewed momentum due to the increasing awareness of head injuries, which result in morbidity and ...

Neuroscience

A Mouse Model of Single and Repetitive Mild Traumatic Brain Injury

Mild Traumatic Brain Injury (mTBI) can result in the acute loss of brain function, including a period of confusion, a loss of consciousness (LOC), focal neurological deficits and even amnesia. Athletes participating in contact sports are at high risk of exposure to large number of mTBIs. In terms of the level of injury in a sporting athlete, a mTBI is defined as a mild injury that does not cause gross pathological changes, but does cause short-term neurological deficits that are spontaneously resolved. Despite previous attempts to model mTBI in mice and rats, many have reported gross adverse effects including skull fractures, intracerebral bleeding, axonal injury and neuronal cell death. Herein, we describe our highly reproducible animal model of mTBI that reproduces clinically relevant symptoms. This model uses a custom made pneumatic impactor device to deliver a closed-head trauma. This impact is made under precise velocity and deformation parameters, creating a reliable and reproducible model to examine the mechanisms that contribute to effects of single or repetitive concussive mTBI.

Athletes absorb several hundred mild traumatic brain injuries (mTBI)/concussions every year; however, the consequence of these on the brain is poorly understood. Therefore, an animal model of single and repetitive mTBI that consistently replicates clinically relevant symptoms provides the means to advance the study of mTBI and concussion.

Mild Traumatic Brain Injury (mTBI) can result in the acute loss of brain function, including a period of confusion, a loss of consciousness (LOC), focal ...

A Novel and Translational Rat Model of Concussion Combining Force and Rotation with In Vivo Cerebral Microdialysis

Persistent cognitive and motor symptoms are known consequences of concussions/mild traumatic brain injury (mTBIs) that can be partly attributable to altered neurotransmission. Indeed, cerebral microdialysis studies in rodents have demonstrated an excessive extracellular glutamate release in the hippocampus within the first 10 min following trauma. Microdialysis offers the clear advantage of in vivo neurotransmitter continuous sampling while not having to sacrifice the animal. In addition to the aforementioned technique, a closed head injury model that exerts rapid acceleration and deceleration of the head and torso is needed, as such a factor is not available in many other animal models. The Wayne State weight-drop model mimics this essential component of human craniocerebral trauma, allowing the induction of an impact on the head of an unrestrained rodent with a falling weight. Our novel and translational rat model combines cerebral microdialysis with the Wayne State weight-drop model to study, in lightly anesthetized and unrestrained adult rats, the acute changes in extracellular neurotransmitter levels following concussion. In this protocol, the microdialysis probe was inserted inside the hippocampus as region of interest, and was left inserted in the brain at impact. There is a high density of terminals and receptors in the hippocampus, making it a relevant region to document altered neurotransmission following concussion. When applied to adult Sprague-Dawley rats, our combined model induced increases in hippocampal extracellular glutamate concentrations within the first 10 min, consistent with the previously reported post-concussion symptomology. This combined weight-drop model provides a reliable tool for researchers to study early therapeutic responses to concussions in addition to repetitive brain injury, since this protocol induces a closed-head mild trauma.

Neurotransmitter alteration is a mechanism of neural dysfunction that occurs after concussion and contributes to the sometimes-catastrophic long-term consequences. This rat model combines microdialysis, allowing in vivo neurotransmitter quantification, with a weight-drop technique exerting rapid acceleration and deceleration of the head and torso, an important factor of human craniocerebral trauma.

Persistent cognitive and motor symptoms are known consequences of concussions/mild traumatic brain injury (mTBIs) that can be partly attributable to ...

Murine Model of Controlled Cortical Impact for the Induction of Traumatic Brain Injury

The Centers for Disease Control and Injury Prevention estimate that almost 2 million people sustain a traumatic brain injury (TBI) every year in the United States. In fact, TBI is a contributing factor to over a third of all injury-related mortality. Nonetheless, the cellular and molecular mechanisms underlying the pathophysiology of TBI are poorly understood. Thus, preclinical models of TBI capable of replicating the injury mechanisms pertinent to TBI in human patients are a critical research need. The controlled cortical impact (CCI) model of TBI utilizes a mechanical device to directly impact the exposed cortex. While no model can full recapitulate the disparate injury patterns and heterogeneous nature of TBI in human patients, CCI is capable of inducing a wide range of clinically applicable TBI. Furthermore, CCI is easily standardized allowing investigators to compare results across experiments as well as across investigative groups. The following protocol is a detailed description of applying a severe CCI with a commercially available impacting device in a murine model of TBI.

Here we describe a protocol for the induction of murine traumatic brain injury via an open-head controlled cortical impact.

The Centers for Disease Control and Injury Prevention estimate that almost 2 million people sustain a traumatic brain injury (TBI) every year in the ...

Low-intensity Blast Wave Model for Preclinical Assessment of Closed-head Mild Traumatic Brain Injury in Rodents

Traumatic brain injury (TBI) is a large-scale public health problem. Mild TBI is the most prevalent form of neurotrauma and accounts for a large number of medical visits in the United States. There are currently no FDA-approved treatments available for TBI. The increased incidence of military-related, blast-induced TBI further accentuates the urgent need for effective TBI treatments. Therefore, new preclinical TBI animal models that recapitulate aspects of human blast-related TBI will greatly advance the research efforts into the neurobiological and pathophysiological processes underlying mild to moderate TBI as well as the development of novel therapeutic strategies for TBI.
Here we present a reliable, reproducible model for the investigation of the molecular, cellular, and behavioral effects of mild to moderate blast-induced TBI. We describe a step-by-step protocol for closed-head, blast-induced mild TBI in rodents using a bench-top setup consisting of a gas-driven shock tube equipped with piezoelectric pressure sensors to ensure consistent test conditions. The benefits of the setup that we have established are its relative low-cost, ease of installation, ease of use and high-throughput capacity. Further advantages of this non-invasive TBI model include the scalability of the blast peak overpressure and the generation of controlled reproducible outcomes. The reproducibility and relevance of this TBI model has been evaluated in a number of downstream applications, including neurobiological, neuropathological, neurophysiological and behavioral analyses, supporting the use of this model for the characterization of processes underlying the etiology of mild to moderate TBI.

We present here a protocol of a blast wave model for rodents to investigate neurobiological and pathophysiological effects of mild to moderate traumatic brain injury. We established a gas-driven, bench-top setup equipped with pressure sensors allowing for reliable and reproducible generation of blast-induced mild to moderate traumatic brain injury.

Traumatic brain injury (TBI) is a large-scale public health problem. Mild TBI is the most prevalent form of neurotrauma and accounts for a large number of ...

Electromagnetic Controlled Closed-Head Model of Mild Traumatic Brain Injury in Mice

Highly reproducible animal models of traumatic brain injury (TBI), with well-defined pathologies, are needed for testing therapeutic interventions and understanding the mechanisms of how a TBI alters brain function. The availability of multiple animal models of TBI is necessary to model the different aspects and severities of TBI seen in people. This manuscript describes the use of a midline closed head injury (CHI) to develop a mouse model of mild TBI. The model is considered mild because it does not produce structural brain lesions based on neuroimaging or gross neuronal loss. However, a single impact creates enough pathology that cognitive impairment is measurable at least 1 month after injury. A step-by-step protocol to induce a CHI in mice using a stereotaxically guided electromagnetic impactor is defined in the paper. The benefits of the mild midline CHI model include the reproducibility of the injury-induced changes with low mortality. The model has been temporally characterized up to 1 year after the injury for neuroimaging, neurochemical, neuropathological, and behavioral changes. The model is complementary to open skull models of controlled cortical impact using the same impactor device. Thus, labs can model both mild diffuse TBI and focal moderate-to-severe TBI with the same impactor.

The protocol describes mild traumatic brain injury in a mouse model. In particular, a step-by-step protocol to induce a mild midline closed head injury and the characterization of the animal model is fully explained.

Highly reproducible animal models of traumatic brain injury (TBI), with well-defined pathologies, are needed for testing therapeutic interventions and ...

rmTBI Induction in Mice via a Closed-Head Injury Method

Modified Mouse Model of Repetitive Mild Traumatic Brain Injury Incorporating Thinned-Skull Window and Fluid Percussion

Mild traumatic brain injury is a clinically highly heterogeneous neurological disorder. Highly reproducible traumatic brain injury (TBI) animal models with well-defined pathologies are urgently needed for studying the mechanisms of neuropathology after mild TBI and testing therapeutics. Replicating the entire sequelae of TBI in animal models has proven to be a challenge. Therefore, the availability of multiple animal models of TBI is necessary to account for the diverse aspects and severities seen in TBI patients. CHI is one of the most common methods for fabricating rodent models of rmTBI. However, this method is susceptible to many factors, including the impact method used, the thickness and shape of the skull bone, animal apnea, and the type of head support and immobilization utilized. The aim of this protocol is to demonstrate a combination of the thinned-skull window and fluid percussion injury (FPI) methods to produce a precise mouse model of CHI-associated rmTBI. The primary objective of this protocol is to minimize factors that could impact the accuracy and consistency of CHI and FPI modeling, including skull bone thickness, shape, and head support. By utilizing a thinned-skull window method, potential inflammation due to craniotomy and FPI is minimized, resulting in an improved mouse model that replicates the clinical features observed in patients with mild TBI. Results from behavior and histological analysis using hematoxylin and eosin (HE) staining suggest that rmTBI can lead to a cumulative injury that produces changes in both behavior and gross morphology of the brain. Overall, the modified CHI-associated rmTBI presents a useful tool for researchers to explore the underlying mechanisms that contribute to focal and diffuse pathophysiological changes in rmTBI.

Author Spotlight: Optimizing Rodent Models for Investigating the Mechanisms and Rehabilitation in Repeated Mild Traumatic Brain Injury

This protocol presents a modified mouse model of repetitive mild traumatic brain injury (rmTBI) induced via a closed-head injury (CHI) method. The approach features a thinned-skull window and fluid percussion to reduce the inflammation commonly caused by meninges exposure, along with improved reproducibility and accuracy in modeling rmTBI in rodents.

Mild traumatic brain injury is a clinically highly heterogeneous neurological disorder. Highly reproducible traumatic brain injury (TBI) animal models ...

CHILD Model &#8212; Recapitulating Juvenile Concussion and Long-Term Outcomes in Mice

A Pediatric Concussion Model in Mice: Closed Head Injury with Long-Term Disorders (CHILD)

Concussions and mild traumatic brain injuries (mTBI) during childhood represent a significant health endangerment, with many patients later in life exhibiting debilitating physiological, neurological, and psychosocial outcomes. The cellular and molecular pathophysiological mechanisms are relatively unknown, and this significant gap effectively precludes investigations into specific therapeutic strategies to mitigate chronic sequelae. No single animal concussion model recapitulates all the features reported in human subjects, and current models are designed to answer specific research questions. We set out to develop a juvenile concussion that recapitulates clinical early, and long-term symptomology encountered, termed Closed Head Injury with Long-term Disorder (CHILD). In this model, a concussive force via an electromagnetic impactor is delivered to the head of a lightly anesthetized unrestrained post-natal day 17 (P17) mouse, allowing free rotation of the head. Mice are placed on a tightly stretched tin foil across a stereotactic device, and the impactor is carefully aligned with the targeted cortical region. The electromagnetic impactor facilitates the selection of impact depth, dwell, and duration to determine injury severity. A strength of this model is that it allows head rotation, an important clinical feature. After impact, mice are immediately monitored for righting time and time to explore their environment, followed by their return to their dam. Increasing the severity of concussion results in intracranial bleeds in a subset of mice. Mice can be routinely monitored for behavior and neuroimaging over their lifespan, as desired. Various injury severities mimic the heterogeneous nature of juvenile concussions. The current standard CHILD model exhibits no skull fracture, no observable conventional neuroimaging change (similar to clinical), but leads to progressive and persistent neuronal death, altered diffusion MRI, modified neuronal activity and plasticity, increased gliosis, and progressive behavioral perturbations with age. In summary, this CHILD model mimics the early and long-term features observed in many clinical concussion patients.

Pediatric concussions can result in long-term sequelae with physiological and psychological perturbations. This pediatric concussion mouse model results in long-term neuroinflammation, white matter alterations, and neuronal modifications with behavioral dysfunction. The model can be adapted to differential impact locations or repeated concussions to assess lifetime changes.

Concussions and mild traumatic brain injuries (mTBI) during childhood represent a significant health endangerment, with many patients later in life ...

Development of an Uncomplicated Mild Traumatic Brain Injury Model Modified by Weight-Drop Method and Evidenced by Magnetic Resonance Imaging

Mild traumatic brain injury (mTBI), known as concussion, accounts for more than 85% of brain injuries globally. Specifically, uncomplicated mTBI showing negative findings in routine clinical imaging in the acute phase hinders early and appropriate care in these patients. It has been acknowledged that different impact parameters may affect and even accelerate the progress of subsequent neuropsychological symptoms following mTBI. However, the association of impact parameters during concussion to the outcome has not been extensively examined. In the current study, an animal model with closed-head injury (CHI) modified from the weight-drop injury paradigm was described and demonstrated in detail. Adult male Sprague-Dawley rats (n = 20) were randomly assigned to CHI groups with different impact parameters (n = 4 per group). Longitudinal MR imaging studies, including T2-weighted imaging and diffusion tensor imaging, and sequential behavioral assessments, such as modified neurological severity score (mNSS) and the beam walk test, were conducted over a 50-day study period. Immunohistochemical staining for astrogliosis was performed on day 50 post-injury. Worse behavioral performance was observed in animals following repetitive CHI compared to the single injury and sham group. By using longitudinal magnetic resonance imaging (MRI), no significant brain contusion was observed at 24 h post-injury. Nevertheless, cortical atrophy and alteration of cortical fractional anisotropy (FA) were demonstrated on day 50 post-injury, suggesting the successful replication of clinical uncomplicated mTBI. Most importantly, changes in neurobehavioral outcomes and image features observed after mTBI were dependent on impact number, inter-injury intervals, and the selected impact site in the animals. This in vivo mTBI model combined with preclinical MRI provides a means to explore brain injury on a whole-brain scale. It also allows the investigation of imaging biomarkers sensitive to mTBI across varying impact parameters and severity levels.

Here, we present a protocol to establish a closed-head injury animal model replicating the neuroimage outcome of uncomplicated mild traumatic brain injury with the preserved brain structure in the acute phase and long-term brain atrophy. Longitudinal magnetic resonance imaging is the primary method used for evidence.

Mild traumatic brain injury (mTBI), known as concussion, accounts for more than 85% of brain injuries globally. Specifically, uncomplicated mTBI showing ...

Generating a Mouse Model of Traumatic Brain Injury Using an Impactor Device

Source: Schwulst, S. J. et al. <a href="https://app.jove.com/v/60027">Murine Model of Controlled Cortical Impact for the Induction of Traumatic Brain Injury.</a> J. Vis. Exp. (2019)
This video demonstrates the procedure for inducing traumatic brain injury (TBI) in a mouse model. An anesthetized mouse with an exposed skull is taken to create an opening in the skull, and then a controlled cortical injury is induced using an impact device. The injury damages the brain tissue, causing impaired cognitive function and motor coordination.

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.
1. Induce ...