Abstract 112: Clinical scale MSC-derived extracellular vesicles enhance poststroke neuroplasticity in a non-human primate model of stroke

Introduction: 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. Methods: We developed a scalable production method for MSC-EVs using a 3D bioprocessing platform. EVs were isolated with filter and tangential flow filtration and characterized through electron microscopy, nanoparticle tracking analysis, nanoflow cytometry analysis, proteomic and lipodomic analysis using mass spectrometry, and RNA sequencing. We determined the appropriate dosage and frequency of intravenous administration of EVs in a mouse stroke model. We then confirmed the efficacy of EVs in a marmoset model of stroke. Improvement in behavioral tests and MRI-based neuroplasticity were compared between the control and EV groups through blind evaluation. The proteome profiles of the infarcted hemisphere were also evaluated. Results: EV products showed suitable lot-to-lot consistent. In a mouse stroke model, intravenous administration of a dose of 6 x 10 8 EVs for five days resulted in the smallest infarct volume and improvement in motor function, with no significant toxicity observed at the tested dosages in the preclinical toxicity studies. Intravenous administration of an equivalent dose (3.5 x 10 9 EVs for five days) in a marmoset model of stroke improved motor functions and anatomical connectivity on diffusion tensor imaging and reduced infarct volume. Proteomics analyses of the infarcted region indicated that EV treatment promoted neurogenesis and synapse function-related protein expression. Conclusions: This study is the first to demonstrate that a clinical-scale EV product is safe and significantly enhances functions recovery and neuroplasticity in a non-human primate model of stroke, offering a promising treatment for human stroke.