Investigation of Mechanosensory Signaling in the Pathogenesis of Traumatic Brain Injury in Human iPSC-derived Cortical Brain Organoids

Project Summary/Abstract Global incidence of Traumatic Brain Injury (TBI) is on the rise, particularly among athletes, military personnel, and elderly citizens1. TBI represents a spectrum of mild to severe injuries that share many long-term pathologies and clinical symptoms such as Tau and TDP43 pathology, axonal injury, neuronal death, and increased risk of

depression and neurodegenerative diseases2-6. Although end-stage pathologies are well characterized from post-mortem samples, the molecular mechanisms contributing to injury remain poorly understood in part due to the difficulty of studying live brains in human patients and the variable biophysical processes that occur between

patients. As a result, available treatment options remain limited and are largely ineffective61. Previous studies of TBI conducted in animal models present with edema, inflammation, and blood-brain barrier disruption following an induced trauma6,7. Although important to the pathophysiology of TBI, this complex cascade of events

complicates our ability to accurately understand cell autonomous injury mechanisms. Therefore, a reductionist system to study the response of distinct cell types to TBI would be beneficial for identifying and targeting changes that occur post-injury. To this end, we will utilize a 3-D cortical organoid culture system grown from human

induced Pluripotent Stem Cells (iPSCs) to elucidate cell autonomous mechanisms of injury and degeneration caused by TBI8. We have developed a unique system of focused ultrasonic injury to mimic TBI in vitro which recapitulates key pathologic and transcriptional features of in vivo models. This allows for detailed study of both

acute and chronic changes following an induced trauma, and provides a platform to integrate environmental and genetic contributions to injury while preserving human-specific biology. Using this system, we will combine bulk RNA-seq transcriptomic analysis with biochemical and immunoassays to uncover novel cell-type specific injury

mechanisms. Using iPSC lines from patients with neurodegenerative diseases, we will test how TBI modulates genetically-induced disease mechanisms. Finally, we will test a mouse model of cortical controlled impact (CCI) to validate our findings in vivo. This proposal will greatly enhance our understanding of specific injury

mechanisms in discrete cell types and may help to identify novel neuroprotective therapeutic targets.