Abstract WMP111: Intra-Arterial Administration of Cerebral Endothelial Cell Derived Small Extracellular Vesicles Reduces Neurovascular Damage and Improves Neurological Outcome After Acute Ischemia in the Aged Rat

Stroke is a leading cause of death and disability worldwide, mainly affecting the elderly. Endovascular thrombectomy (EVT) is a standard of care therapy for stroke patients with large-vessel occlusion, however, the majority of these patients do not achieve full functional improvement. The present study tested the hypothesis that intra-arterial (IA) administration of cerebral endothelial cell derived small extracellular vesicles (CEC-sEVs) following transient middle cerebral artery occlusion (tMCAO) improves stroke outcome in the aged rat. CEC-sEVs (1x10 ¹¹ particles/injection) isolated from healthy adult rats were employed. Male aged rats (18 months, n=10/group) subjected to 3h tMCAO were randomly divided into the experimental groups. To examine whether IA injection of CEC-sEVs improves stroke outcome, CEC-sEVs were administered via the internal carotid artery (ICA) immediately following reperfusion by withdrawal of the occlusion filament. To examine whether intravenous administration (IV) of CEC-sEVs during tMCAO and then followed by IA CEC-sEVs upon reperfusion further enhances stroke outcome, CEC-sEVs were given at 30 min of tMCAO via a tail vein and upon reperfusion via the ICA. The ischemic rats treated with IA saline were used as a control. Neurological outcome and infarct volume were assessed in a blinded manner. IA CEC-sEVs upon reperfusion significantly reduced infarct volume (24±5% vs 31±6% in saline, p<0.05) which was associated with robust improvement of neurological function from weeks 2 to 4 after tMCAO compared to saline treated rats. Moreover, rats treated with CEC-sEVs IV at 30min followed by IA treatment upon reperfusion further reduced infarct volume (16±6%) compared to rats treated with IA saline or CEC-sEVs. These rats also exhibited robust and early improvement of neurological function starting at 1d after tMCAO. In conclusion, IA administration of CEC-sEVs upon reperfusion significantly reduces ischemic damage, while an additional early (30min post stroke) dose of IV CEC-sEVs further enhances and accelerates the therapeutic effect of IA CEC-sEVs in the aged rats after tMCAO. Our data suggest that CEC-sEVs could potentially may be a therapy to amplify the efficacy of EVT even for elderly patients with acute ischemic stroke.