Name: controlled cortical impact model for traumatic brain injury
Uploaded: 2014-08-05T16:00:00.000+00:00
Duration: 5 min 30 s
Description: Watch this Scientific Journal Video about Controlled Cortical Impact Model for Traumatic Brain Injury at JoVE.com

This work was supported by funding from the Indiana Spinal Cord &#38; Brain Injury Research Grants (SCBI 200-12), the Ralph W. and Grace M. Showalter Research Award, Indiana University Biological Research Grant, NIH grants RR025761 and 1R21NS072631-01A.

Animal Care 
Male C57 BL/6 mice were group-housed and kept in a 12/12 hr light/dark cycle with free to access to food and water ad libitum. The animals used in this protocol were 10-12 weeks old. All procedures were performed under protocols approved by Indiana University&#8217;s Animal Care and Use Committee.
1. Surgical Preparation
<ol>
	<li>Anesthetize the mouse using a Ketamine/xylazine&#160;mixture (87.7 mg/ml Ketamine and 12.3 mg/ml Xylazine)&#160;and administer&#160;(1 ml/kg) via IP injection.</li>
	<li>Shave the head of the mouse between the ears.</li>
	<li>Apply a petroleum-based jelly&#160;to the eyes of the mouse to prevent drying out during surgery.</li>
	<li>Clean the shaven area with 10% iodine. Then use 70% ethanol to clean off the iodine.</li>
	<li>Fix the mouse head in the stereotactic frame using the ear bars and bite plate. Ensure the brain is stable.</li>
</ol>
2. Craniectomy
<ol>
	<li>Make a longitudinal incision in the middle of the head with scissors. Use a hemostat to hold skin off to the left side.</li>
	<li>Use a cotton-tipped applicator to remove the blood and tissue on the bone to expose the skull. Allow exposed skull to dry for 1 min.</li>
	<li>Use forceps to apply pressure and ensure that the skull remains immobile. Identify anatomical landmarks Lambda (caudal aspect) and Bregma (frontal aspect). Draw a circle in the center of Lambda and Bregma with a 4&#160;mm diameter and 0.5&#160;mm away from the midline.</li>
	<li>Use a drill to cut along the marked circle. Gently blow bone dust away. Do not drill completely through the bone to prevent damaging the dura mater.</li>
	<li>Use forceps to remove bone and expose the dura mater.</li>
</ol>
3. Impaction
The impact system includes a control box to set impact parameters, an actuator to perform the impaction, and a stereotactic frame to secure the actuator and mouse head for impact.
<ol>
	<li>Pre-set the velocity of the actuator to 3&#160;m/sec before surgery.</li>
	<li>Pre-set different deformation depth to induce different injury severities. Deformation depths of 0.0-0.2 mm, 0.5-1.0 mm, and 1.2-2.0 mm would result in mild, moderate, and severe TBIs, respectively. This protocol explained how to achieve a moderately severe brain injury with a deformation depth of 1&#160;mm by using a velocity of 3&#160;m/sec.</li>
	<li>Attach the actuator to the holder in the stereotactic frame and use the micromanipulators moving it to secure the round, flat tip of the actuator (3&#160;mm diameter) in the center of the open skull area. Then adjust the tip at an angle parallel to the surface of impact site.</li>
	<li>Establish the zero point by moving down the actuator in the extending model until the tip touches the surface of the impact site. Then set the Z channel on the stereotactic control panel to zero.</li>
	<li>Retract the impactor tip while simultaneously moving the actuator down 1&#160;mm.</li>
	<li>Hit the impact button to strike the injury site and achieve a deformation depth of 1&#160;mm.</li>
</ol>
4. Injury Site Closure
<ol>
	<li>Use cotton-tipped applicators to remove any blood following impact, but do not touch the injury area.</li>
	<li>Place mouse on a warm pad to maintain body temperature.</li>
	<li>Once bleeding has stopped, suture the wound closed. Put the animal back into the clean cage and allow it to recover from the surgery overnight on the warm pad.</li>
	<li>Administer&#160;Buprenorphine 0.05-0.10 mg/kg SQ every 8-12 hr&#160;for 2 days after surgery.</li>
</ol>

<ol>
	<li>Menon, D. K., Schwab, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Position+statement:+definition+of+traumatic+brain+injury.">Position statement: definition of traumatic brain injury.</a> Arch Phys Med Rehabil. 91 (11), 1637-1640 (2010).</li><li>Lighthall, J. W., Dixon, C. E., 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=Experimental+models+of+brain+injury.">Experimental models of brain injury.</a> J Neurotrauma. 6 (2), 83-97 (1989).</li><li>Dixon, C. E., Clfton, G. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+controlled+cortical+impact+model+of+traumatic+brain+injury+in+the+rat.">A controlled cortical impact model of traumatic brain injury in the rat.</a> J Neurosci Methods. 39 (3), 253-262 (1991).</li><li>Scheff, S. W., Baldwin, S. 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=Morris+water+maze+deficits+in+rats+following+traumatic+brain+injury:+lateral+controlled+cortical+impact.">Morris water maze deficits in rats following traumatic brain injury: lateral controlled cortical impact.</a> J Neurotrauma. 14 (9), 615-627 (1997).</li><li>Smith, D. H., Soares, H. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+model+of+parasagittal+controlled+cortical+impact+in+the+mouse:+cognitive+and+histopathologic+effects.">A model of parasagittal controlled cortical impact in the mouse: cognitive and histopathologic effects.</a> J Neurotrauma. 12 (2), 169-178 (1995).</li><li>Hannay, H. J., Feldman, 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=Validation+of+a+controlled+cortical+impact+model+of+head+injury+in+mice.">Validation of a controlled cortical impact model of head injury in mice.</a> J Neurotrauma. 16 (11), 1103-1114 (1999).</li><li>Natale, J. E., Ahmed, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gene+expression+profile+changes+are+commonly+modulated+across+models+and+species+after+traumatic+brain+injury.">Gene expression profile changes are commonly modulated across models and species after traumatic brain injury.</a> J Neurotrauma. 20 (10), 907-927 (2003).</li><li>Anderson, R. W., Brown, C. 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=Impact+mechanics+and+axonal+injury+in+a+sheep+model.">Impact mechanics and axonal injury in a sheep model.</a> J Neurotrauma. 20 (10), 961-974 (2003).</li><li>Lighthall, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Controlled+cortical+impact:+a+new+experimental+brain+injury+model.">Controlled cortical impact: a new experimental brain injury model.</a> J Neurotrauma. 5 (1), 1-15 (1988).</li><li>Chen, S., Pickard, J. D., 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=Time+course+of+cellular+pathology+after+controlled+cortical+impact+injury.">Time course of cellular pathology after controlled cortical impact injury.</a> Exp Neurol. 182 (1), 87-102 (2003).</li><li>Long, J. B., Bentley, T. L., 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=Blast+overpressure+in+rats:+recreating+a+battlefield+injury+in+the+laboratory.">Blast overpressure in rats: recreating a battlefield injury in the laboratory.</a> J Neurotrauma. 26 (6), 827-840 (2009).</li><li>Clark, R. S., Schiding, J. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neutrophil+accumulation+after+traumatic+brain+injury+in+rats:+comparison+of+weight+drop+and+controlled+cortical+impact+models.">Neutrophil accumulation after traumatic brain injury in rats: comparison of weight drop and controlled cortical impact models.</a> J Neurotrauma. 11 (5), 499-506 (1994).</li><li>Werner, C., Engelhard, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pathophysiology+of+traumatic+brain+injury.">Pathophysiology of traumatic brain injury.</a> Br J Anaesth. 99 (1), 4-9 (2007).</li><li>Colicos, M. A., Dixon, C. E., 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=Delayed,+selective+neuronal+death+following+experimental+cortical+impact+injury+in+rats:+possible+role+in+memory+deficits.">Delayed, selective neuronal death following experimental cortical impact injury in rats: possible role in memory deficits.</a> Brain Res. 739 (1-2), 111-119 (1996).</li><li>Raghavendra Rao, V. L., Dogan, 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=Traumatic+brain+injury+leads+to+increased+expression+of+peripheral-type+benzodiazepine+receptors,+neuronal+death,+and+activation+of+astrocytes+and+microglia+in+rat+thalamus.">Traumatic brain injury leads to increased expression of peripheral-type benzodiazepine receptors, neuronal death, and activation of astrocytes and microglia in rat thalamus.</a> Exp Neurol. 161 (1), 102-114 (2000).</li><li>Gao, X., Chen, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Moderate+traumatic+brain+injury+promotes+neural+precursor+proliferation+without+increasing+neurogenesis+in+the+adult+hippocampus.">Moderate traumatic brain injury promotes neural precursor proliferation without increasing neurogenesis in the adult hippocampus.</a> Exp Neurol. 239, 38-48 (2013).</li></ol>

The authors have nothing to disclose.

The most critical steps for successfully generating consistent TBIs using an electronic magnet impact system to cause a CCI are: 1) stably fixing the mouse head in the stereotactic frame; 2) generating the same size of bone window between mice and removing the bone without damaging the dura under it during craniectomy; 3) correctly positioning the impact tip in the center of the open area and establishing the zero point before impacting.
A mouse head must be fixed in the stereotactic frame very tightly before impact. Loose fixation will generate large variations in injury level. To ensure fixation is stable, use forceps to apply pressure on the skull once the mouse head is fixed in the stereotactic frame and confirm that the skull remains immobile. Take precautionary measures to avoid infection of the exposed skull. After exposing the skull, move to the most difficult part of the controlled cortical impact surgery: drilling a circular cut into the skull without damaging the dura mater underneath.
The optimum size of drill bit tip is 0.5&#160;mm. The suitable speed is 10,000-20,000 rpm; however, using a higher speed can facilitate drilling a better bone window. Drilling will generate heat that can damage the brain, particularly in young mice whose bone and dura are attached. To prevent damaging the brain, apply saline to the skull surface while drilling. Applying saline will make it necessary to use a dissecting microscope in order to see the drilled circle. When mice mature, a space develops between the bone and dura, thus the effect of heat generated by drilling would produce a minimal impact.
While drilling, move the drill bit slowly and constantly along a circular path. Otherwise, the bit may move off the line or go directly through the bone and damage the brain tissue. Gently touch the bone window using forceps to inspect the drilling. If the skull bone easily moves up and down, move the fine tip of the forceps into the space between the bone and the dura. Then lift up to remove the whole bone, thus creating the window. Do not lift bone from one side to another, because doing so may hurt the brain tissue. Making identically sized bone windows is critical for generating consistent brain injuries. Due to intracranial pressure, the brain will bulge out of the open area once the bone is removed, thus causing minor brain deformation. If the bone window size varies, the level of brain deformation will be different, being similar to the brain surface curve in the impact site. The bone was not repositioned over the impact site following surgery since it was smaller than the bone window. Doing so would cause the bone to adhere directly to the brain tissue. Applying glue to seal the bone window might result in increased intracranial pressure. Examining an impact site 3 weeks after a CCI surgery a new membrane was found covering the brain tissue with no brain tissue growth outside of the impact site. No known histological changes occur due to a lack of bone covering.
The electronic magnet impact system is exceedingly stable and can precisely control the velocity and deformation depth. However, due to the design, the coil connected to the impact tip can shift while striking and result in a shift of impact site. This is the major cause of inconsistent injuries, barring no other complications. Despite the possibility for shifting the impact site, the controlled cortical impact method remains more precise and easier to control compared to the fluid percussion and weight drop methods, thus making CCI a preferred method for investigating the short-term and long-term effects of TBIs, as well as possible therapeutic treatments. Although important for TBI research, removing a portion of the skull prior to impact limits the clinical relevance of the CCI model.
The protocol above describes the procedure to produce a moderate TBI in a mouse. The impact site may range from 1-6&#160;mm in diameter depending on the animal and severity of injury desired. Although the protocol stated the impact tip was 3&#160;mm in diameter, a 4&#160;mm in diameter craniectomy was performed in order to prevent accidentally striking bone. In addition to altering the size of the impact site, the speed of the impactor and depth of deformation may be adjusted to reach the severity needed.

Traumatic brain injury (TBI) is defined as an alteration in brain function, or other evidence of brain pathology, caused by an external force1. TBIs remain a serious health problem throughout the world, particularly in the United States. According to the Centers for Disease Control and Prevention, at least 1.7 million TBIs occur annually in the United States resulting in 30.5% of all injury-related deaths. In 2000, the direct medical costs and indirect costs of TBIs totaled an estimated $76.5 billion in the United States alone. Although technological and therapeutic advancements in preceding decades have improved the quality and length of life for those suffering from TBIs, no effective pharmaceutical or preventative treatments currently exist. Due to the complexity and wide-reaching effects of TBIs, including tissue lesions, cell death, and axon degeneration, no two injuries are identical; thus, no current TBI model for animals accurately reproduces all aspects of TBI as seen in humans. However, animal models do provide the ability to produce nearly identical injuries necessary to investigate various effects of TBI with the hope of further understanding the clinical manifestations of TBIs.
The controlled cortical impact (CCI) model uses an impact system to deliver physical impact to the exposed dura of an animal. It induces TBIs ranging from mild to severe similar to those experienced by humans. This injury was first characterized in the ferret2 and was later adapted for use in the rat3,4, mouse5-7, and sheep8. Since the first characterization, the site of injury has been placed both over the midline2,9 and the lateral cortex10. CCI provides an easy and accurate method of investigating the effects and potential treatments for TBIs.
In addition to the CCI model, the fluid percussion and weight drop models are commonly used to produce TBIs. However, these models present limitations, including less control over injury parameters, producing histopathalogical changes not seen in human TBIs, and greater incidence of accidental death in mice3,5,10. The blast wave model is also used to produce TBIs. Although the blast wave model does not reproduce the histopathalogical changes seen following a mechanical impact, this model does accurately produce TBIs experienced particularly by military personnel11. The controlled cortical impact model is easy to control due to the precise control over deformation parameters such as time, velocity, and depth of impact5. Such accuracy makes replicating nearly identical injuries across an entire group of animals more feasible. Most importantly, CCI reproduces TBIs with features seen in human TBIs12. However, there is no single animal model that is entirely successful in reproducing the complete spectrum of pathological changes observed after TBI. Further research is necessary to fully reveal the acute and chronic changes that occur after TBI.
Two types of injuries occur following a TBI: primary and secondary injuries. The primary injury occurs at the moment of impact and is not sensitive to therapeutic treatments; however, the secondary injuries that persist after the initial injury are subject to treatments13. The controlled cortical impact model produces the primary injury, thus allowing researchers to investigate the effects of TBI and potential therapeutic treatments for the potentially long-lasting effects of secondary injuries. Areas of potential research using the CCI model include neuronal death, cerebral edema, neurogenesis, vascular effects, histopathalogical changes, and memory deficits and more3,13-16.

<table><tbody><tr><td>Povidone-iodine 7.5%</td><td>Purdue product L.P.</td><td></td><td>Surgical scrub</td></tr><tr><td>Cotton tipped applicators</td><td>Henry Schein</td><td>100-6015</td><td>Remove blood and debris</td></tr><tr><td>Scissor</td><td>Fine Science Tools</td><td>14084-08</td><td>Surgery</td></tr><tr><td>Forcept</td><td>Fine Science Tools</td><td>11293-00</td><td>Surgery</td></tr><tr><td>Hemostat</td><td>Fine Science Tools</td><td>13021-12</td><td>Surgery</td></tr><tr><td>Rechargeable Cordless Micro Drill</td><td>Stoelting</td><td>58610</td><td>Combine with Burrs for generating the bone window</td></tr><tr><td>Burrs for Micro Drill</td><td>Fine Science Tools</td><td>19007-05</td><td></td></tr><tr><td>Suture monofilament</td><td>Ethicon</td><td>G697</td><td>Suture</td></tr><tr><td>tert-Amyl alcohol</td><td>Sigma</td><td>152463-250ML</td><td>Making 2.5% Avertin</td></tr><tr><td>2,2,2-Tribromoethanol</td><td>Sigma</td><td>T48402-25G</td><td>Making 2.5% Avertin</td></tr></tbody></table>

controlled cortical impact model for traumatic brain injury

Every year over a million Americans suffer a traumatic brain injury (TBI). Combined with the incidence of TBIs worldwide, the physical, emotional, social, and economical effects are staggering. Therefore, further research into the effects of TBI and effective treatments is necessary. The controlled cortical impact (CCI) model induces traumatic brain injuries ranging from mild to severe. This method uses a rigid impactor to deliver mechanical energy to an intact dura exposed following a craniectomy. Impact is made under precise parameters at a set velocity to achieve a pre-determined deformation depth. Although other TBI models, such as weight drop and fluid percussion, exist, CCI is more accurate, easier to control, and most importantly, produces traumatic brain injuries similar to those seen in humans. However, no TBI model is currently able to reproduce pathological changes identical to those seen in human patients. The CCI model allows investigation into the short-term and long-term effects of TBI, such as neuronal death, memory deficits, and cerebral edema, as well as potential therapeutic treatments for TBI.

The controlled cortical impact model produces TBIs ranging in severity from mild to severe. Post-impact the amount of cranial swelling, bleeding, and cranial distortion at the impact site will reveal the injury severity resulting from the speed and deformation depth parameters. Mild TBIs result in cranial swelling at the impact site and slight bleeding due to the limited dura breach. A moderate TBI exhibits cranial swelling and increased bleeding due to dura breach upon impaction (Figure 1). The difference between a moderate and severe TBI may be difficult to distinguish until visualized on fixed tissues using a microscope (Figure 2); however, a severe TBI may occasionally display amplified distortion and cranial swelling post-impact. The CCI model may be used to determine the effects of multiple aspects of TBIs, including tissue deformation (Figure 2), neuronal death, and histopathalogical changes.
<img alt="Figure 1" fo:content-width="6.5in" src="/files/ftp_upload/51781/51781fig1highres.jpg" width="600" /> 
Figure 1. Controlled cortical impact model for moderate traumatic brain injury. The procedure for controlled cortical impact is illustrated in this figure. A) The mouse head was stably fixed on the stereotactic frame with ear bar and mouth bits. B) The left skull was exposed and 4 mm circle was drawn in the center of bregma and lambda. C) The bone was removed by the drilling to generate a window for impact. D) The actuator was attached on the stereotactic frame and the zero point on Z-axis was set up. E) The brain tissue was distorted and caused bleeding with impact. F) The bleeding stopped several minutes after impact and the blood was removed by cotton applicator. <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/51781/51781fig1highres.jpg" target="_blank">Click here to view larger image.</a>
<img alt="Figure 2" fo:content-width="6.5in" src="/files/ftp_upload/51781/51781fig2highres.jpg" width="600" /> 
Figure 2. Histology for Moderate Traumatic Brain Injuries. A) A na&#239;ve 10-12 week old mouse brain was removed. B) A 10-12 week old mouse brain was used as a sham control. C) The brain of a 10-12 week old mouse was removed 24 hr after a moderate TBI using the CCI model. D) The brain of a 10-12 week old mouse was removed 6 weeks after a moderate TBI using the CCI model. An indention in the brain tissue is evident at the site of impact. E) Nissl staining was performed on a sham control 10-12 week old mouse brain to show the normal histology. F) Nissl staining was performed on a 10-12 week old mouse brain that had received a moderate TBI using the CCI model. A cavity is visible extending deep into the cortex. <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/51781/51781fig2highres.jpg" target="_blank">Click here to view larger image.</a>

Watch this Scientific Journal Video about Controlled Cortical Impact Model for Traumatic Brain Injury at JoVE.com

Controlled Cortical Impact Model for Traumatic Brain Injury

Traumatic brain injuries (TBIs) remain a serious health problem. Using the controlled cortical impact surgery model, research on the effects of TBI and possible treatment methods may be performed.

Every year over a million Americans suffer a traumatic brain injury (TBI).  Combined with the incidence of TBIs worldwide, the physical, emotional, ...

controlled-cortical-impact-model-for-traumatic-brain-injury

Universidad San Sebastian

Research

JoVE Journal

Medicine

28.5K Views.  Indiana University School of Medicine. Traumatic brain injuries (TBIs) remain a serious health problem. Using the controlled cortical impact surgery model, research on the effects of TBI and possible treatment methods may be performed.

Video: Controlled Cortical Impact Model for Traumatic Brain Injury

Controlled Cortical Impact Model of Mouse Brain Injury with Therapeutic Transplantation of Human Induced Pluripotent Stem Cell-Derived Neural Cells

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality worldwide. Disease pathology due to TBI progresses from the primary mechanical insult to secondary injury processes, including apoptosis and inflammation. Animal modeling has been valuable in the search to unravel injury mechanisms and evaluate potential neuroprotective therapies. This protocol describes the controlled cortical impact (CCI) model of focal, open-head TBI. Specifically, parameters for producing a mild unilateral cortical injury are described. Behavioral consequences of CCI are analyzed using the adhesive tape removal test of bilateral sensorimotor integration. Regarding experimental therapy for TBI pathology, this protocol also illustrates a process for transplanting cultured cells into the brain. Neural cell cultures derived from human induced pluripotent stem cells (hiPSCs) were chosen for their potential to show superior functional restoration in human TBI patients. Chronic survival of hiPSCs in the host mouse brain tissue is detected using a modified DAB immunohistochemical process.

This protocol demonstrates methodologies for a mouse model of open-skull traumatic brain injury and transplantation of cultured human induced pluripotent stem cell-derived cells into the injury site. Behavioral and histologic tests of outcomes from these procedures are also described in brief.

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality worldwide. Disease pathology due to TBI progresses from the primary mechanical ...

Developmental Biology

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.

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 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 ...

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 ...

Neuroscience

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 ...

A Preclinical Controlled Cortical Impact Model for Traumatic Hemorrhage Contusion and Neuroinflammation

Cerebral contusion is a severe medical problem affecting millions of people worldwide each year. There is an urgent need to understand the pathophysiological mechanism and to develop effective therapeutic strategy for this devastating neurological disorder. Intraparenchymal hemorrhage and post-traumatic inflammatory response induced by initial physical impact can aggravate microglia/macrophage activation and neuroinflammation which subsequently worsen brain pathology. We provide here a controlled cortical impact (CCI) protocol that can reproduce experimental cortical contusion in mice by using a pneumatic impactor system to deliver mechanical force with controllable magnitude and velocity onto the dural surface. This preclinical model allows researchers to induce moderately severe focal cerebral contusion in mice and to investigate a wide range of post-traumatic pathological progressions including hemorrhage contusion, microglia/macrophage activation, iron toxicity, axonal injury, as well as short-term and long-term neurobehavioral deficits. The present protocol can be useful for exploring the long-term effects of and potential interventions for cerebral contusion.

Intraparenchymal hemorrhage and neuroinflammation accompanied by cerebral contusion can trigger severe secondary brain injury. This protocol details a mouse controlled cortical impact (CCI) model allowing researchers to study hemorrhage contusion and post-traumatic immune responses and explore potential therapeutics.

Cerebral contusion is a severe medical problem affecting millions of people worldwide each year. There is an urgent need to understand the ...

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 ...

Assessing Changes in Synaptic Plasticity Using an Awake Closed-Head Injury Model of Mild Traumatic Brain Injury

Mild traumatic brain injuries (mTBIs) are a prevalent health issue in North America. There is increasing pressure to utilize ecologically valid models of closed-head mTBI in the preclinical setting to increase translatability to the clinical population. The awake closed-headed injury (ACHI) model uses a modified controlled cortical impactor to deliver closed-headed injury, inducing clinically relevant behavioral deficits without the need for a craniotomy or the use of an anesthetic.
This technique does not normally induce fatalities, skull fractures, or brain bleeds, and is more consistent with being a mild injury. Indeed, the mild nature of the ACHI procedure makes it ideal for studies investigating repetitive mTBI (r-mTBI). Growing evidence indicates that r-mTBI can result in a cumulative injury that produces behavioral symptoms, neuropathological changes, and neurodegeneration. r-mTBI is common in youths playing sports, and these injuries occur during a period of robust synaptic reorganization and myelination, making the younger population particularly vulnerable to the long-term influences of r-mTBI.
Further, r-mTBI occurs in cases of intimate partner violence, a condition for which there are few objective screening measures. In these experiments, synaptic function was assessed in the hippocampus in juvenile rats that had experienced r-mTBI using the ACHI model. Following the injuries, a tissue slicer was utilized to make hippocampal slices to evaluate bidirectional synaptic plasticity in the hippocampus at either 1 or 7 days following the r-mTBI. Overall, the ACHI model provides researchers with an ecologically valid model to study changes in synaptic plasticity following mTBI and r-mTBI.

Here, it is demonstrated how an awake closed-head injury model can be used for examining the effects of repeated mild traumatic brain injury (r-mTBI) on synaptic plasticity in the hippocampus. The model replicates important features of r-mTBI in patients and is used in conjunction with in vitro electrophysiology.

Mild traumatic brain injuries (mTBIs) are a prevalent health issue in North America. There is increasing pressure to utilize ecologically valid models of ...

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 ...

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 ...