Modeling Mild Traumatic Brain Injury In-Vitro Using PHuman Choroid Plexus Endothelial Cells

Abstract

Over 2.5 million Traumatic Brain Injuries (TBIs) occur each year due to falls, motor vehicle accidents, assaults, and sports (Brain Trauma Foundation, 2023). Short- and long-term consequences of TBI can include headache, cognitive impairment, seizures, hypoxia, and ischemia. Human TBI studies are diffcult due to the confounding variables of type and mechanism of injury, severity of injury, and length of time to present to emergency departments. While animal models exist, it is our goal to develop an in-vitro model of TBI using primary human brain cell cultures to examine cellular responses in real time. While the blood-brain barrier has been studied extensively post-TBI due to its role in ischemia and hypoxia, there is a dearth of research on the blood-CSF-barrier (BCSFB), the choroid plexus, and its response post-TBI. After culturing primary human choroid plexus endothelial cells (ScienCell Cat #1300) on a flexible membrane, we subjected them to mechanical strain using the FlexCell tension system and collected supernatant at 3-, 6-, 12-, 24-, 48-, 72-, and 96-hours post injury. The FlexCell tension bioreactor system uses positive and negative air pressure to apply mechanical elongation strain mimicking mild shearing injury. Using R&D cytokine arrays (R&D Systems, Cat# ARY005B), we measured 36 different cytokines, chemokines and acute phase proteins including C5a, GM-CSF, ICAM-1, IL-1, IL-6, TNFα, IFNγ, CCL5/RANTES, etc. We hypothesized that we would see a pro-inflammatory response (IL-1β, IL-6, TNFα) within 24 hours after one or two 12% mechanical strain injuries compared to the control of no strain, as seen in the literature. However, there were not significant increases in cytokine signaling until 24-48 hours post-injury, and in regulatory cytokines, such as CCL2, MIP1α/MIP1β, IL-2, IL-12, & IL-17, that lasted as long as 96-hours. This effect was more pronounced in the two strain verses one strain model and control, as expected. Interestingly, anti-inflammatory cytokine IL-10 was significantly increased in the one strain model, but not two strain model, 48 hours post-insult. As the choroid plexus is a niche for T cell stimulation in the central nervous system (Strominger et al., 2018), these results indicate a complex immunological response that seems to favor T-Cell response over monocytes/macrophages. These experiments were completed with the lowest mechanical strain of the FlexCell system and future experiments are warranted to determine if a stronger mechanical strain is needed to produce the pro-inflammatory response seen in the literature in mild to severe models of TBI. This project was funded by a Senior Research Grant from the Indiana Academy of Science and from a Faculty Research Development Grant from Marian University College of Osteopathic Medicine. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.