Reactive astrocyte derived extracellular vesicles promote functional repair post stroke

Reactive astrocytes are both neurotoxic and pro-regenerative. Their reparative roles after injury have been demonstrated, but how they play a contributing role to regeneration remains question. Here, we investigate the use of astrocytic extracellular vesicles from primary astrocytes cultured in reactive conditions in promoting repair after ischemic stroke. Our studies show that extracellular vesicles derived from reactive astrocytes that co-express a significant number of reactive genes (155 upregulated including log2 of 9.61 for Lcn2) and axonal outgrowth genes (59 upregulated including log2 of 3.49 Ntn1) are necessary for improved regenerative outcomes, including axonal infiltration, vascularization, and improved behavioral recovery. Proteomic analysis of the extracellular vesicles show that astrocytes enrich pro-reparative proteins in extracellular vesicles with only 30 proteins relating to inflammatory or complement pathways loaded out of a total of 1073 proteins. Further, we show that the use of a biomaterial scaffold is necessary for the improved regeneration observed from reactive astrocyte extracellular vesicles. These studies show that reactive astrocytes use extracellular vesicles enriched with pro-repair proteins to promote recovery after injury.