Endothelial cells (ECs) tightly regulate the passage of ions, molecules, and cells from the blood into the brain and vice versa as part of the blood-brain barrier (BBB). Astrocytes aid in the formation and maintenance of the BBB. Aside from direct communication, astrocytes and ECs also release extracellular vesicles (EVs) to communicate with each other and other cells. EVs carry genetic information, proteins, and other signalling molecules. This cargo changes relative to the donor cell state, which can influence different processes in recipient cells.This project investigates this bi-directional indirect communication of these cells at the BBB, in both physiological and pathological conditions. While previous studies have found that astrocyte- conditioned media (ACM) has a positive effect on the barrier function of ECs, we found that endothelial cell permeability is significantly increased upon incubation with ACM. While EVs isolated from ACM using ExtraPEG had no effect on the permeability of ECs, the expression levels of several tight junction genes were altered.Neuroinflammation is common in several neurological disorders. Breakdown of the BBB is a hallmark of neuroinflammation, altering the brain’s tightly controlled microenvironment. Additionally, astrocytes can become activated, releasing proinflammatory cytokines, which can exacerbate BBB-breakdown. Preliminary studies have shown that EVs from healthy cells can ‘rescue’ the barrier in pathological contexts. Future studies investigating the cargo and associated effects of EVs isolated from healthy cells on models of neuroinflammation could elucidate the role EVs have in both physiological and pathological conditions, aiding the development of therapeutic interventions against neuroinflammation.