Abstract P793: Extracellular Vesicles Enhance Blood-Brain Barrier Integrity by Nf-κB Dependent Regulation of Abcb1 in Stroke Mice

Abstract

Extracellular vesicles (EVs) derived from neural progenitor cells (NPCs) enhance post-stroke neurological recovery, albeit the underlying mechanisms remain elusive. Since previous research described an enhanced post-stroke integrity of the blood-brain barrier (BBB) upon systemic transplantation of NPCs, we wondered if NPC-derived EVs affect BBB stability and which cellular mechanisms might be involved in the process. Using an in vitro co-culture model of brain endothelial cells (ECs) and astrocytes, cells were treated with EVs or PBS and exposed to oxygen-glucose-deprivation (OGD) injury. The readout parameters focused on the expression of ABCB1, an ATP-binding cassette (ABC) transporter expressed on ECs contributing to BBB integrity. Further in vitro analysis examined the pro-inflammatory NF-κB pathway, the permeability and the transcellular electrical resistance (TER) of cultured ECs. In vitro data was finally confirmed using a rodent stroke model. Cultured ECs displayed increased ABCB1 levels when exposed to OGD, which was reversed by treatment with EVs. The latter was due to an EV-induced inhibition of the NF-κB pathway. Using a BBB co-culture model of ECs and astrocytes exposed to OGD, EVs stabilized the BBB and ABCB1 levels without affecting TER. Likewise, EVs yielded reduced Evans blue extravasation, decreased ABCB1 expression as well as an inhibition of the NF-κB pathway and downstream matrix metalloprotease-9 activity in stroke mice. The EV-induced inhibition of the NF-κB pathway resulted in a post-stroke modulation of immune responses. Our findings suggest that EVs enhance post-stroke BBB integrity via ABCB1 and MMP-9 regulation, attenuating inflammatory cell recruitment by inhibition of the NF-κB pathway.