Rationale:
Mesial temporal lobe epilepsy (MTLE) is one of the most common forms of treatment-resistant epilepsy in adults. MTLE patients often have a history of a preceding neurological injury and the inflammation and cell death associated with such injuries are believed to contribute to the development of epilepsy. However, the mechanisms underlying the development of MTLE are still incompletely understood. Extracellular vesicles (EVs) are small cell-derived particles that are important for intercellular communication. Emerging evidence suggests that EV content is altered in MTLE, but whether these alterations are protective or pathogenic is unclear. To address this question, we examined the content and functional properties of EVs following status epilepticus (SE) in the pilocarpine mouse model of MTLE.
Methods:
Mice were subjected to pilocarpine-induced SE and neocortical and hippocampal samples were collected at 24 hours and 10 days post-SE. Control mice were similarly handled but were not administered pilocarpine. EVs were isolated via gentle tissue dissociation, ultracentrifugation, and sucrose density gradient separation. EV populations were subjected to nanoparticle tracking analysis (NTA) to evaluate concentration and size. To examine EV function, we compared the ability of each EV preparation to alter cell growth and confer protection in an
in vitro cell death assay. Further experiments to determine miRNA content are being conducted.
Results:
NTA on EVs from neocortical tissue collected 24 hours after SE showed no differences in gross properties including EV number and average size. EVs from control mice resulted in increased cell growth. This effect was also observed with EVs following SE. Furthermore, the ability of EVs to protect against cell death was similar between the two EV populations.
Conclusions:
These initial results suggest that gross properties of neocortical-derived EVs are unaltered in the 24-hour period following SE. Additionally, SE did not alter the effect of these EVs on cell growth or survival. This analysis is being expanded to include EVs isolated from the hippocampus, as well as at different time points after SE. Changes in the miRNA content of EVs are also being examined. These results provide novel insight into the role of EVs in the pathogenesis of epilepsy.
Funding:
This project was supported by NIH Training Grant 5T32NS096050-24 and a predoctoral fellowship from the American Epilepsy Society.