EFFECTS OF METABOLISM ON MESENCHYMAL STEM CELL-DERIVED EXTRACELLULAR VESICLES
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Mesenchymal stem cells (MSCs) are under investigation for a wide variety of therapeutic applications. It has been determined that paracrine secretions are responsible for a significant portion of MSC bioactivity. Among these secretions, extracellular vesicles (EVs) have been discovered to have therapeutic potential. EVs have many applications, such as reduction of myocardial injury, wound repair, and promotion of angiogenesis. A recent spark in MSC- derived EV interest stems from the potential advantages they have over MSC transplantation. EVs are considered more stable, have a well-defined clearance pathway in vivo, and pose less safety risks due to their inability to differentiate. There is increasing interest in MSC-derived EVs and their potential clinical application, however, there are many barriers to realistic, widespread EV-based therapy. One of the more prevalent issues is a lack of knowledge behind the impact of various cell culture parameters, which have been shown to affect both MSCs and the EVs they produce. Specifically, evidence shows that cell culture conditions impact metabolic pathways, which provide important signals that contribute to MSC behavior and function. However, there have been no specific studies on the potential impact of MSC metabolism on EVs. My overarching hypothesis is that MSC EV production and function are dependent on the metabolic state of the parent MSCs. To test this hypothesis, two key metabolic pathways, glycolysis and oxidative phosphorylation, were inhibited to examine their effects on EV production. Metabolic effects on MSC EV bioactivity were also assessed using gap closure assays. Experiments were performed in both 2D and spheroid culture to assess continuity of results between platforms. In 2D culture, metabolic pathway inhibition did not impact MSC EV production capacity but did decrease EV bioactivity. In microcavity- well culture plates, metabolic pathway inhibition decreased both MSC EV production capacity and EV bioactivity. These results indicate it is very likely that metabolism plays a mechanistic role in MSC EV production and bioactivity. Further studies are required to conclusively determine if metabolism impacts MSC EV production capacity, and they are also needed to better understand what causes metabolism to affect MSC EV bioactivity.