Equine mesenchymal stem cell derived extracellular vesicle immunopathology biomarker discovery.

The use of mesenchymal stem cells (MSCs) in human and veterinary clinical applications has become a subject of increasing importance due to their roles in immunomodulation and regenerative processes. MSCs are especially relevant in equine medicine because they may have the ability to treat prevalent musculoskeletal disorders, among other conditions. However, recent evidence suggests that the components secreted by MSCs, particularly extracellular vesicles (EVs), are responsible for these properties. EVs contain proteins and nucleic acids, which possess an active role in intercellular communication and can be used as therapeutics. However, because the intersection of equine veterinary medicine with EVs remains a relatively new field, there is a demand to identify biomarkers that can discern and enrich for therapeutic EVs, progressing their clinical efficacy. In this study, we identified and characterized 84 miRNAs, between three equine donors involved in immunomodulation in cell and EV subjects. We discovered distinct groups of shared miRNAs, like miR-21-5p and miR-451a, that are abundant and enriched between the donors' EVs, respectively. By mapping and comparing the MSC-EV miRNA expression, we discovered many pathways that are involved in immunomodulation and tissue regenerative processes related to equine clinical applications. Therefore, the miRNAs highlighted in this article can be used as valuable biomarkers for screening MSC-derived EVs for potential equine therapy.