A Single Cell and Spatial Transcriptomic Investigation of Traumatic Brain Injury: Novel insights into endothelial-derived Eph signaling
| dc.contributor.author | de Jager, Caroline Dana | en |
| dc.contributor.committeechair | Theus, Michelle Hedrick | en |
| dc.contributor.committeemember | Xie, Hehuang David | en |
| dc.contributor.committeemember | Rossmeisl, John H. | en |
| dc.contributor.committeemember | Kehn-Hall, Kylene Wesley | en |
| dc.contributor.department | Graduate School | en |
| dc.date.accessioned | 2025-01-10T09:01:24Z | en |
| dc.date.available | 2025-01-10T09:01:24Z | en |
| dc.date.issued | 2025-01-09 | en |
| dc.description.abstract | A staggering number of injury related disabilities and deaths are connected to traumatic brain injury (TBI) worldwide. Traumatic brain injury (TBI) involves an intricate and multifaceted cascade of events, starting with an initial mechanical impact followed by secondary injury brought on by numerous physiological changes that involve significant dysfunction at the cellular and molecular level. One major predictor of severe TBI outcome is the extent of blood-brain barrier (BBB) disruption, which under normal conditions prevents the passage of bacteria, neurotoxins, and macromolecules from entering the brain. Disruption of the BBB is linked to worse clinical outcomes in patients in both the acute, subacute, and chronic phases. However, the principal mechanisms responsible for regulating BBB permeability, where, and for how long that permeability occurs following TBI remains to be elucidated. Previous research has shown increased mRNA and protein expression of ephrin receptor A4 (EphA4), a well-established axon guidance molecule, within hours and days following TBI. This study is the first comprehensive investigation of the role of endothelial cell-specific EphA4 in TBI on regulating the BBB using advanced techniques like single-cell RNA and spatial transcriptomic sequencing, in addition to our newly established dual dye-labeling system. The central hypothesis is that endothelial cell-specific deletion of EphA4 enhances BBB integrity, characterized by changes in single cell gene expression consistent with improved barrier function, altered cellular metabolism, and reduced neuroinflammation within the BBB niche. This hypothesis will be tested by leveraging spatial sequencing to identify upregulation of genes associated with BBB stability and neuroprotection and utilizing a novel approach for assessing BBB permeability that addresses the limitations of traditional Evans Blue Dye (EBD) assays, including lack of spatial resolution, enabling precise analysis of molecular weight-dependent extravasation patterns. | en |
| dc.description.abstractgeneral | Traumatic brain injury (TBI) is a major global cause of disability and death, involving a complex series of events that lead to both immediate and ongoing brain damage. One key aspect of brain injury is the disruption of the blood-brain barrier (BBB), a protective shield that controls the flow of blood into the brain and prevents harmful substances from entering. When the BBB is compromised, it can worsen the damage caused by TBI. Despite its importance, how and why the BBB breaks down after TBI remains poorly understood. This study focused on a specific protein, EphA4, which is found in the cells that make up the blood vessels in the brain. We wanted to see if deleting EphA4 from these cells would help maintain BBB integrity and reduce brain inflammation after injury. To do this, we used advanced techniques, including single-cell RNA sequencing (which looks at gene expression in individual cells) and new methods to measure the extent of BBB disruption. The study also aimed to improve traditional methods of assessing BBB breakdown, which previously lacked the ability to measure the BBB's spatial and temporal changes in detail. We found that deleting EphA4 from the blood vessels in mice helped maintain the BBB and reduce inflammation in the brain after injury. We also developed a new method to measure BBB disruption more accurately, showing that smaller molecules leaked into the brain tissue more than larger ones. Overall, this research suggests that EphA4 plays an important role in regulating the BBB after TBI and that targeting it could offer new ways to protect the brain from injury in the future. | en |
| dc.description.degree | Doctor of Philosophy | en |
| dc.format.medium | ETD | en |
| dc.identifier.other | vt_gsexam:42334 | en |
| dc.identifier.uri | https://hdl.handle.net/10919/124086 | en |
| dc.language.iso | en | en |
| dc.publisher | Virginia Tech | en |
| dc.rights | In Copyright | en |
| dc.rights.uri | http://rightsstatements.org/vocab/InC/1.0/ | en |
| dc.subject | Vascular biology | en |
| dc.subject | EphA4 | en |
| dc.title | A Single Cell and Spatial Transcriptomic Investigation of Traumatic Brain Injury: Novel insights into endothelial-derived Eph signaling | en |
| dc.type | Dissertation | en |
| thesis.degree.discipline | Translational Biology, Medicine and Health | en |
| thesis.degree.grantor | Virginia Polytechnic Institute and State University | en |
| thesis.degree.level | doctoral | en |
| thesis.degree.name | Doctor of Philosophy | en |
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