Molecular mechanisms of blast and blunt injury in a novel 3D bioengineered brain-like tissue

We have developed a novel 3D human brain-like tissue model to study the molecular mechanisms of blast and blunt impact injury. This tissue model, composed of human
neurons, astrocytes, and microglia seeded onto silk scaffolds and encased in a collagen hydrogel, allows for reproducible control over cellular composition, environment, and injury. Blasts are generated in the Advanced Blast Simulator (ABS), a
shockwave tube using forced air to induce an air blast. Blunt injury is produced using a pneumatic cylinder that reproducibly imposes a fixed rate and force. We have used this novel system to establish and characterize critical aspects of both blast and blunt injury. In this proposal, we will use this 3D culture system to dissect and compare
molecular and structural alterations induced by these different injury modalities. We will focus on three critical pathological alterations that occur immediately after TBI: mitochondrial dysfunction, axonal structural and functional deficits, and inflammatory changes. Specifically, we will ask (1) What is the role of glycolytic alterations and subsequent mitochondrial dysfunction in injury propagation after blast and blunt injury? (2) What changes in axonal microtubule structure occur due to blunt and blast injury, and what transport deficits result? And (3) Which cell types contribute to specific cytokine profiles post blunt and blast injury, and do these inflammatory changes contribute to injury progression? We will further determine whether specific critical pathologic mechanisms induced by forced air in the ABS
are replicated using airborne shock generated by an explosive blast. While there is increased monitoring of blast exposures of our military personnel, there is no mechanism at present to convert a specific blast exposure to any level of pathophysiological response. We will perform a dose-response to both air blast and explosive blast to determine the threshold blast pressure at which specific injury mechanisms are initiated, and the potential escalation of pathophysiology with increased blast intensity. The experiments outlined in this proposal will provide a comprehensive analysis of molecular and cellular responses to blunt and blast injury in order to develop better tools for monitoring and tracking injuries in theatre and developing therapies for treating our injured warfighters.

Our warfighters are constantly exposed to the risk of injury during combat. Traumatic brain injury is the most common traumatic injury in the military, and blast-induced neurotrauma is of specific military relevance . In combat, the warfighter may also suffer blunt TBI. Even supposedly mild TBIs can have long-term consequences for the ability of that warfighter to continue in theatre due to problems with cognition, memory, pain, or sleep. Our proposal encompasses a novel combination of biochemical, pharmacologic, imaging and transcriptomic approaches to provide a comprehensive mechanistic understanding of the response to blast and blunt injury over time. We will generate concrete knowledge of the differences and similarities between blast and blunt injury at the molecular and cellular level that could lead to novel therapeutics, improved neuropathologic detection, and a deeper understanding of the dose-response relationship between different blast intensities and degree of molecular and cellular damage. This would help develop criteria for risk assessment and potentially allow for more accurate sensing of neuropathologic damage in theatre.