Optical imaging helps understand the mechanics of blast traumatic brain injury

An optical imaging method explores the mechanics of cavitation-induced injury to better understand blast traumatic brain injuries.

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The scale at which blast traumatic brain injury (bTBI) injuries occur and manifest is unknown, but recent studies suggest that rapid cavitation bubble collapse may be a potential mechanism for studying it. So, Jonathan Estrada, a doctoral student in the School of Engineering at Brown University (Providence, RI), and colleagues are using an optical imaging method to explore the mechanics of cavitation-induced injury to better understand bTBIs.

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Estrada is working under the guidance of Christian Franck, along with colleagues from Brown University and the University of Michigan (Ann Arbor, MI). The research team is using a laser, an optical microscope, and rat neurons inside a gel-like substance to mimic brain tissue to examine bTBIs. The laser pulse is sent through the "brain tissue" under the microscope while a high-speed camera—recording 270,000 frames/s—captures the laser creating a bubble, the bubble breaking, and the damage this causes to the rat neurons. The team imaged affected neurons before and immediately after injury, Estrada explains.

The significance of the research team's work is that while postmortem studies have begun to show differences in brain pathology—such as astroglial (star-shaped glial cell) scarring—between patients exposed to blast injury and those with bTBI, the manifestation of injury over time still isn't well understood. "Our work, using the simplified bubble and neuron culture model, aims to begin bridging the gap between the mechanics of blast injury and cell damage," Estrada says.

Although the results are in the preliminary stage, the researchers found that the maximum bubble radius is nearly identical to the zone of neuron fragmentation immediately after injury, Estrada adds. A previous study done by Estrada and his colleagues focused on concussive (blunt) TBI via uniaxial compression of neurons, which found that injury was distributed over entire cultures rather than localized to one area, he says.

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A confocal image of neurons before and after cavitation injury was induced. (Image credit: Estrada et al.)

The research team's method allows them to see the injury history of the cells within cultures—before and just after injury with live-cell fluorescence, during injury with high-speed imaging, and then injury manifestation at later time points via immunostaining. "Quantifying temporal injury history is essential to understanding, diagnosing, and working toward informed treatment of blast TBI," Estrada notes.

Estrada presented the research team's work during the Biophysical Society's 61st Annual Meeting (Feb. 11-15, 2017; New Orleans, LA) on February 13th. To view the abstract, please visit www.abstractsonline.com/pp8/#!/4279/presentation/1225.

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