(684a) Invited Talk: Delivery of Mitochondria-Containing Extracellular Vesicles to the Blood-Brain Barrier

Extracellular vesicles (EVs) are natural, nano-sized carriers of cellular cargo. EVs play a key role in intercellular communication via transfer of their internal components, including lipids, proteins and nucleic acids. We studied EV subsets that are either large (microvesicle: MV) or small (exosome: EXO) particles isolated from human brain endothelial cells (BECs). MVs naturally incorporate mitochondria during their biogenesis. Our work has demonstrated that (1) the larger MVs but not the smaller EXOs contain mitochondria, (2) MVs transfer mitochondria into recipient BECs and cortical and hippocampal neurons in mouse brain slices, (3) and MVs increase cellular ATP levels and mitochondrial function in the recipient oxygen-glucose deprived (OGD) BECs. Importantly, recipient OGD BECs treated with MVs displayed superior mitochondrial function compared to BECs treated with control EXOs that lack mitochondria. (4) BEC-derived MVs transfer their innate mitochondria that subsequently localized with recipient cell mitochondria in primary human BECs, suggestive of mitochondrial fusion and (5) mice injected with MVs demonstrated a 50% reduction in brain tissue damage and improved neurological functions compared to vehicle-injected mice in a mouse middle cerebral artery occlusion model of ischemia/reperfusion injury (stroke). In summary, we, for the first time, have demonstrated therapeutic efficacy of the larger, mitochondria-containing EVs in a mouse model of ischemic stroke. Delivery of functional mitochondria is an effective approach to protect the post-ischemic blood-brain barrier—and therefore is a promising strategy to decrease long-term neurological dysfunction post-stroke. Based on the promising potential of the naïve MV mitochondria, we have further engineered mitochondria-enriched MVs (mito-EVs) as an innovative approach to improve mitochondrial quality and quantity in the engineered mito-EVs. Our preliminary results point to the potential of mito-EVs to stimulate de novo mitochondrial biogenesis in recipient cells/tissues. Collectively, our works demonstrate a novel, cell-derived carrier that can deliver functional mitochondria—a platform technology that can be used to treat multiple disorders associated with mitochondrial dysfunction.