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Adam Hedberg-Buenz, Matthew M. Harper, Mark Christopher, Laura Dutca, Todd Scheetz, Randy H Kardon, Michael G Anderson; Investigating the influence of blast on cellularity in the retinal ganglion cell layer in a mouse model of blast-induced traumatic brain injury using a novel semi-automated technique. Invest. Ophthalmol. Vis. Sci. 2014;55(13):1737.
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© ARVO (1962-2015); The Authors (2016-present)
Blast-mediated injuries are the leading cause of combat-related injury in modern warfare. Visual dysfunction has been reported in Veterans with blast-mediated traumatic brain injury (TBI). We have previously shown retinal ganglion cells (RGC) are exquisitely sensitive to blast exposure. However, the magnitude of RGC loss in blast-mediated injury is not yet understood. The purpose of these experiments is to develop a method to quantify cellularity and investigate the influence of blast on the retinal ganglion cell layer (GCL) after blast-induced TBI.
C57BL/6J mice were exposed to an overpressure wave (20 PSI) directed to the head using a custom-built blast chamber (blast-injured). Mice placed in the chamber without blast were used as controls (sham control). At 4 months post-blast, retinas from both blast-injured (n=16) and sham control (n =12) eyes were mounted whole, stained, and imaged by light microscopy. Images were uniformly collected across the retina with equal sampling from the central and peripheral retina. Images were quantitatively assessed for cellularity in the GCL using custom-written macros in Image J.
Retinas from both blast-injured and sham control mice had greater cell densities in the central compared to peripheral retina. In the peripheral retina, blast-injured mice exhibited a significant decrease (p = 0.03) in cell density compared to controls using a Students t-test. In the central retina, blast-injured mice exhibited a trend of reduced cell density compared to controls (not significant). Together, these results indicate exposure to blast causes cellular loss in the GCL in this model. Additionally, this novel semi-automated technique is able to detect subtle changes in cell density.
These results demonstrate that this mouse model of blast-induced TBI recapitulates the neuronal loss in the GCL that contributes to visual dysfunction in humans with TBI. This semi-automated technique provides a useful method to quantitatively assess cellularity in the GCL. Extending our knowledge of RGC susceptibility and mechanistic responses that influence their fate following blast-injury will help in the development of improved clinical testing and treatment of visual deficits to those suffering from TBI.
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