Abstract WP296: Human Vascular Smooth Muscle Cells Derived Small Extracellular Vesicles Reduce the Neurovascular Damage After Stroke in Diabetic Mice

Abstract

Introduction: Stroke patients with type-2 diabetes exhibit exacerbated cerebrovascular dysfunction and increased neurological deficits compared to non-diabetic stroke patients. Vascular smooth muscle cells (VSMCs) play an important role in mediating neurovascular function, however, how VSMCs communicate with cerebral endothelial cells (CECs) has not been studied. In this study, we tested the hypothesis that small extracellular vesicles (sEVs) derived from healthy human VSMCs (VSMC-sEVs) reduce diabetes- and ischemia-neurovascular damage. Methods and Results: VSMC-sEVs were characterized. In vitro CEC permeability assay showed that treatment of hypoxia-challenged human brain microvascular endothelial cells (BMECs) or primary CECs isolated from type-2 diabetic mice (n=6/group) with VSMC-sEVs significantly reduced and augmented cell permeability and trans-endothelial electrical resistance, respectively, compared to non VSMC-sEVs control. Inhibition of sEV endocytosis in BMECs with clathrin (CPZ) or caveolin (Nystatin) inhibitors abrogated the effect of VSMC-sEVs on CEC proliferation and migration. We then examined the effect of VSMC-sEVs on diabetic ischemia in which diabetic mice, with diabetes induced by a high fat diet and streptozotocin, were subjected to permanent MCAo. Middle-age diabetic male mice (10-12m old) were treated with intranasal administration of VSMC-sEVs (1x10 9 particles per injection) or saline (n=12/group) at 24h after cerebral ischemia. We found that VSMC-sEVs treatment significantly increased regional cerebral blood flow and FITC-dextran perfused functional microvessels (17.55% vs 13.32% control) as well as decreased brain hemorrhage and BBB leakage (1.51% vs 1.76% of albumin, p<0.05) in the ischemic border zone 28 days after MCAo compared with the saline treatment mice. Moreover, compared to the saline treatment, VSMC-sEVs significantly improved neurological function after stroke as measured by modified neurological severity score, and foot-fault and adhesive removal tests, respectively. Conclusion: This study suggests that VSMC-sEVs have a therapeutic effect to improve neurological outcome after diabetic stroke, likely by reducing diabetes and ischemia impaired neurovascular function.