Wang, Hai‐Long

Abstract Extracellular vesicles (EVs) are small membrane‐bound structures that originate from various cell types and carry molecular cargos to influence the behaviour of recipient cells. The use of EVs as biomarkers for diagnosis and as delivery vehicles for treatment in a wide range of human disease is a rapidly growing field in research and clinical practice. We hypothesized that electric fields (EFs) could influence the release and content of EVs. To examine this hypothesis, we developed a specialized bioreactor enabling cells to thrive in a three‐dimensional setting, replicating in‐vivo conditions amidst programmable EF environments. We established a three‐step EV purification protocol to achieve high‐density production of EVs. We also performed mass spectrometry‐based proteomics analysis on EV‐carrying proteins and used high‐resolution nanoparticle flowcytometry for single‐vesicle analysis. Findings from this report suggest that electrical stimulation, employing physiologically relevant amplitudes typical in therapeutic deep brain stimulation, influences the release of EVs and their cargo content in a frequency‐dependent fashion. This conclusion could carry significant implications for both fundamental biological understanding and medical advancements. First, it raises an intriguing question about how the endogenous electrical activity of neuronal and other cellular assemblies influence the production and composition of EVs. Second, it reveals a novel underlying mechanism of how therapeutic electrical stimulations can modulate EVs and treat human brain disorders. Third, it provides a novel approach to utilize electrical stimulation for generating desired EV cargos in a programmable setting.

AbstractMicroglial activation has been recognized as a major contributor to inflammation of the epileptic brain. Seizures are commonly accompanied by remarkable microgliosis and loss of neurons. In this study, we utilize the CX3CR1GFP/+ CCR2RFP/+ genetic mouse model, in which CX3CR1+ resident microglia and CCR2+ monocytes are labeled with GFP and RFP, respectively. Using a combination of time‐lapse two‐photon imaging and whole‐cell patch clamp recording, we determined the distinct morphological, dynamic, and electrophysiological characteristics of infiltrated monocytes and resident microglia, and the evolution of their behavior at different time points following kainic acid‐induced seizures. Seizure activated microglia presented enlarged somas with less ramified processes, whereas, infiltrated monocytes were smaller, highly motile cells that lacked processes. Moreover, resident microglia, but not infiltrated monocytes, proliferate locally in the hippocampus after seizure. Microglial proliferation was dependent on the colony‐stimulating factor 1 receptor (CSF‐1R) pathway. Pharmacological inhibition of CSF‐1R reduced seizure‐induced microglial proliferation, which correlated with attenuation of neuronal death without altering acute seizure behaviors. Taken together, we demonstrated that proliferation of activated resident microglia contributes to neuronal death in the hippocampus via CSF‐1R after status epilepticus, providing potential therapeutic targets for neuroprotection in epilepsy.