The National Institutes of Health has awarded Professor Andrew Dunn, Co-Director of the Center for Emerging Imaging Technologies and the Werner W. Dornberger Centennial Teaching Fellow in Engineering, a five-year $1.75 million grant.
Andrew Dunn
The National Institutes of Health has awarded Professor Andrew Dunn, Co-Director of the Center for Emerging Imaging Technologies and the Werner W. Dornberger Centennial Teaching Fellow in Engineering, a five-year $1.75 million grant.
Brain injury during a stroke depends on the extent of oxygen deprivation. This study will measure how much brain damage occurs at various levels of oxygen deprivation by inducing stroke in mice, imaging the extent of cellular damage, and performing experiments to evaluate behavior changes in the mice post-stroke.
Currently the challenge to determining the extent of brain injury from oxygen deprivation lies with accurate measurement of oxygen tension levels. Most current methods for measurement of oxygenation with three-dimensional spatial resolution are invasive. In this study, Professor Dunn's lab is developing a new approach for repeated, noninvasive measurement of oxygen tension that combines an oxygen-sensitive dye with a femtosecond laser. The laser excites the phosphorescent dye only in the vicinity of the laser focus enabling micron scale measurements of oxygen tension.
A further challenge to these measurements is overcoming the blood-brain barrier, a protective barrier that restricts most molecules, including the oxygen sensitive dye, from entering the brain. To combat this challenge, Dunn will collaborate with biomedical engineering colleague Stanislav Emelianov, the Cockrell Family Chair in Engineering Excellence and Co-Director of the Center for Emerging Imaging Technology, and optimize an ultrasound-based approach for temporary disruption of the blood brain barrier. When focused ultrasound is combined with intravenous injection of microbubbles, the blood brain barrier is transiently opened allowing the oxygen sensitive dye to reach the neurons in the brain. Together the ultrasound and laser-based oxygen tension measurements enable tracking of oxygen levels for several months after stroke in mice.
Dunn will measure the cell deterioration against results from his other collaborator Dr. Theresa Jones, a professor of psychology at The University of Texas at Austin. Jones has developed experiments to measure motor skills in the mice.
Experiments should reveal oxygen level thresholds for causing specific damage during a stroke and lend insight into how the brain reorganizes itself after cell damage occurs. This could inform rehabilitation strategies for stroke as well as other disease, including Alzheimer's.
