This work was supported by R01 NS067417 from the National Institute for Neurological Disorders and Stroke (MPB).

These studies were performed in strict accordance with the recommendations in the Guide for the Care and Use of Laboratory Animals of the National Institutes Health. The protocol was approved by the Institutional Animal Care and Use Committee at Georgetown University. Mice were housed in a temperature controlled animal facility and were kept on a 12 h light/12 h dark cycle. Food and water were available ad libitum.
1. Preparation of the mTBI Apparatus
NOTE: T...

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The authors have nothing to disclose.

In humans, mTBI is characterized by a functional impairment in the absence of structural injury. This can occur with, or without, a loss of consciousness1. Exposure to repeat concussions is currently thought to underlie the development and/or progression of neurodegenerative diseases such as CTE4. It is well documented that CTE is commonly found in boxers and football players and although exposure to repeat concussions (including those that do not result in a loss of consci...

Traumatic Brain Injury (TBI) is defined as a head injury sustained from an external physical force, resulting in the disruption of normal brain function. It represents a significant socio-economic and public health burden, with the Center for Disease Control and Prevention 2015 Report to Congress estimating that 2.5 million Americans sustain a TBI every year. This impacts not only the patient&#39;s quality of life, but also places an extremely high economic cost on the community, currently estimated at $76.5 billion annually. The amount of actual brain damage conveyed and the acute phase symptomologies is what defines mild, moderate and severe TBI.
Mild Traumatic Brain Injury (mTBI), also referred to as concussion, accounts for over 70% of TBIs reported each year1. It is most common among athletes who participate in high-risk contact sports including boxing and football2. Unlike moderate or severe forms of TBI, the immediate damage and symptoms associated with mTBI are sometimes not as pronounced3. By contrast, the long-term effects of mTBI can be just as debilitating as those seen in the moderate and severe forms. Those who suffer from repetitive mTBI have been shown to develop chronic traumatic encephalopathy (CTE), as well as other cognitive and degenerative illnesses4. Therefore, it is important to gain a greater understanding of the mechanisms that contribute to the short-term symptoms and overall long-term damage that arises following mTBI.
In humans, the definition of concussion as defined by the Fourth International Conference on Concussion in Sport (Zurich 2012)5 states that the level of injury for sports concussion is mild, does not cause gross pathological changes, but does cause short-term neurological deficits that are spontaneously resolved. Indeed, a recent study investigated the effect of mTBI on cognitive impairment in high school football players, using head impact telemetry systems. This study showed the amount of times players sustained helmet impacts &#62;20 g in a single season ranged from a low of 226 (average, 4.7 per session) to a high of 1855 (average, 38.6 per session)6. Most of these impacts did not result in the clinical diagnosis of a concussion; but evidence of functional changes in brain function could be observed using fMRI6. The brain changes that cause these functional changes are unknown, and therefore there is a pressing need to have a reliable and reproducible model to facilitate research into the effects of concussive and subconcussive mTBI.
Despite previous attempts to model mTBI in mice and rats7, many report adverse effects. In particular, most rodent models are limited in their repetitive nature using fewer than five mTBIs impacts, as well as having adverse pathological events including intracerebral bleeding, skull fractures, severe axonal injury, neuronal cell death, and increased mortality8,9,10,11,12. Herein, we describe a mouse model of mTBI that is closer to the true definition of concussion in humans. This model recapitulates many of the symptoms observed in human mTBI, such as the mechanical force that results in the transient loss of consciousness with no overt gross brain pathology. Furthermore, it is advantageous in the fact that it can be utilised for both single impact and repetitive impact paradigms over long time periods as reported previously13.

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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.

The use of this novel mTBI device allows for single and repetitive mild head injuries without risk of skull fracture or structural brain damage. The model uses a custom made pneumatic Teflon impactor device to deliver a closed head mechanical energy impact. The 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 (Figure ...

Watch this Scientific Journal Video about A Mouse Model of Single and Repetitive Mild Traumatic Brain Injury at JoVE.com

A Mouse Model of Single and Repetitive Mild Traumatic Brain Injury

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 ...

The overall goal of this mouse model of traumatic brain injury or TBI, is to create a reliable and reproducible method for examining the mechanisms that underlie concussive and sub-concussive brain injury. This method facilitates the investigation of key questions in the mouse TBI field such as, what are the physiological changes that occur in the brain after single or repeat concussion. The main advantage of this technique is that the injury device is specifically designed to allow repetitive head impacts without the risk of skull fracture or structural brain damage.Before beginning the procedure, turn on the compressed air and initialize the high velocity pneumatic impactor to a pressure setting of 861.85 kilo pascals. Calibrate the machine to the desired velocity and dwell time. Place the gel filled base, such that the mid line is perpendicular to the trajectory of the impactor tip and record the weights of all of the mice to be used.Next, transfer and anesthetize the mouse to the MTBI apparatus, placing the head on the gel pad with the skull perpendicular to the impactor tip and tape over the mouse head, to create a flat surface and to ensure the ears are away from the impact site. Lower the polytetrafluoroethylene impactor tip to align with the sagittal mid line in the center of the head, just behind the eyes. The impator tip is 10 millimeters in diameter and will cover the majority of the head area.Adjust the impactor until it is just touching the surface of the mouse's head. Then, retract the tip and manually dial down the required deflection depth to 7.5 millimeters. Now, arm the data acquisition control system and to press the trigger button to impact the mouse's head.Immediately after the final impact, transfer the mouse to the bench top in the supine position, without the nose cone and use a stopwatch to measure the latency of the return of righting reflex to determine the loss of consciousness time and the time to return, of spontaneous ambulation. Upon recovery to normal behavior, return the animal to its home cage. The return of the righting reflex time, is an acute neurological evaluation of injury severity that can be used to quantify the loss of consciousness after MTBI.For example, animals that receive a single MTBI, demonstrate significantly increased loss of consciousness and ambulation times, compared to sham animals. In repeat injury paradigms, loss of consciousness and ambulation times are significantly increased on all of the testing days. IBA one staining for microglia and macrophages reveals changes in experimental mouse inflammatory profiles, after repeat MTBI, compared to single MTBI or sham animals.Repeat MTBI animals display a strong IBA one immunoreactivity that is limited to the optic tract, with no evidence of gray matter inflammation in the cortex, hippocampus or other brain areas. Once mastered, this technique can be done in five minutes if it is performed properly.

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10.9K Görüntüleme.  Georgetown University Medical Center. The overall goal of this mouse model of traumatic brain injury or TBI, is to create a reliable and reproducible method for examining the mechanisms that underlie concussive and sub-concussive brain injury. This method facilitates the investigation of key questions in the mouse TBI field such as, what are the physiological changes that occur in the brain after single or repeat concussion. The main advantage of this technique is that the injury device is specifically designed to allow repetitiv...