Clinical Scale MSC-Derived Extracellular Vesicles Enhance Poststroke Neuroplasticity in Rodents and Non-Human Primates

Abstract

Stroke is a leading cause of death and disability. The therapeutic potential of mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) has shown considerable promise in rodent models of stroke. However, the therapeutic efficacy and safety of clinical-scale MSC-EVs for ischemic stroke are not well elucidated, especially in non-human primates. We developed a scalable production method for MSC-EVs using a 3D bioprocessing platform. EVs were isolated with a filter and tangential flow filtration and characterized using electron microscopy, nanoparticle tracking analysis, nanoflow cytometry analysis, proteomic and lipidomic analysis using mass spectrometry, and RNA sequencing. We determined the appropriate dosage and frequency of intravenous administration of EVs in a mouse stroke model. A biodistribution study of the selected dose regimen was performed using the internal cargo of EVs, human mitochondrial DNA. We then confirmed the efficacy of EVs in a marmoset stroke model. Improvement in behavioural tests and MRI-based neuroplasticity were compared between the control and EV groups through blinded evaluation. The proteome profiles of the infarcted hemisphere were also evaluated. EV products showed suitable lot-to-lot consistency. In a mouse stroke model, intravenous administration of a dose of 6 × 10⁸ EVs for 5 days resulted in the smallest infarct volume and improvement in motor function. A biodistribution study showed that EVs were rapidly distributed into systemic organs and were relatively specifically distributed to the infarcted brain areas. Intravenous administration of an equivalent dose (3.5 × 10⁹ EVs for 5 days) in a marmoset stroke model significantly improved motor functions and anatomical connectivity on diffusion MRI, and significantly reduced infarct volume. Proteomics analyses indicated that EV treatment promoted neurogenesis, synapse organization, and vascular development. In conclusion, this study is the first to demonstrate that a clinical-scale EV product is safe and significantly enhances function recovery and neuroplasticity in a non-human primate stroke model, offering a promising treatment for human stroke.