Extracellular Vesicles Deliver Mitochondria and HSP27 Protein to Protect the Blood-Brain Barrier

Abstract

AbstractIschemic stroke causes brain endothelial cell death and damages tight junction integrity of the blood-brain barrier (BBB). We engineered endothelial cell-derived extracellular vesicles (EVs) for the delivery of exogenous heat shock protein 27 (HSP27) and harnessed the innate EV mitochondrial load as a one-two punch strategy to increase brain endothelial cell survival (via mitochondrial delivery) and preserve their tight junction integrity (via HSP27 delivery). We demonstrated that the medium-to-large (m/lEV) but not small EVs (sEV) transferred their mitochondrial load that subsequently colocalized with the mitochondrial network of the recipient primary human brain endothelial cells. This mitochondrial transfer increased the relative ATP levels and mitochondrial function in the recipient endothelial cells. EV/HSP27 mixtures decreased the paracellular permeability of small and large molecular mass fluorescent tracers in oxygen glucose-deprived primary human brain endothelial cells. This one-two punch approach to increase the metabolic function and structural integrity of brain endothelial cells is a promising strategy for BBB protection and prevention of long-term neurological dysfunction post-ischemic stroke.Graphical AbstractHighlights➢Small and medium-to-large extracellular vesicles (sEVs and m/lEVs) were studied➢m/lEVs have a greater mitochondrial load and increase mitochondrial function➢m/lEV mitochondria colocalized with mitochondria in recipient brain endothelial cells➢EV/HSP27 mixtures decreased dextran permeability in brain endothelial cells (BECs)➢A combination of EV mitochondria and exogenous HSP27 mitigates BEC ischemic damage