Cargo Analysis and MRI-Based Therapeutic Assessment of Iron Oxide Labelled Extracellular Vesicles of Hypoxia Human Stem Cells in Ischemic Stroke

Human mesenchymal stem cells (hMSCs) have been under investigation in preclinical and clinical settings for treating neurological disorders in recent years. Predominantly due to paracrine effects in vivo, hMSC-secreted extracellular vesicles (EVs) are at the forefront of these investigations. In this study, the therapeutic efficacy of hypoxia hMSCs and the secreted EVs labelled with iron oxides was evaluated in a preclinical model of ischemic stroke. Transcriptome and proteomics analysis of hMSCs under hypoxia indicated alterations in metabolic pathways and EV biogenesis. Hypoxia preconditioning increased EV yield by 57% with similar EV size and exosomal marker expression. EV cargo analysis using proteomics and microRNA-sequencing revealed that hypoxia preconditioning upregulated expression of metabolic proteins related to hypoxia-inducible factor signalling, neurogenesis and EV biogenesis. Magnetic resonance imaging following in vivo administration of iron oxide-labelled hMSCs and EVs provided assessment of biodistribution and therapeutic efficacy. The results indicated differential recovery in sodium levels in rats following hMSC and EV administration compared to the vehicle-only group, supported by lactate levels and functional assessment. hMSC-EVs localized to the ischemic lesion and evoked a therapeutic response after a single bolus injection. This study has significance in developing human stem cell-free therapeutics for treating ischemic stroke.