Acid sphingomyelinase deactivation post-ischemia/ reperfusion promotes cerebral angiogenesis and brain remodeling via small extracellular vesiclesAcid sphingomyelinase deactivation post-ischemia/ reperfusion promotes cerebral angiogenesis and brain remodeling via small extracellular vesicles

Acid sphingomyelinase (ASM) inhibitors, which are clinically used as anti-depressants for ~60 years, have recently been shown to enhance stroke recovery in rodents. Using mice and cerebral microvascular endothelial cells exposed to ischemia/reperfusion (I/R) we show that the antidepressants amitriptyline, fluoxetine and desipramine induce angiogenesis in an ASM-dependent way by releasing small extracellular vesicles (sEVs) from endothelial cells, which have bona fide characteristics of exosomes and which, similar to sEVs released during I/R, promote angiogenesis. Post-I/R, ASM inhibition elicits a profound brain remodeling response with increased blood-brain barrier integrity, reduced brain leukocyte infiltrates and increased neuronal survival. The ASM inhibitor-mediated release of sEVs has disclosed an elegant target, via which stroke recovery can be amplified. Key words: Antidepressant, ceramide, exosome, focal cerebral ischemia, middle cerebral artery occlusion, sphingomyelin, stroke recovery