Exogenous Delivery of Sphingomyelinase Mediates Mesenchymal Stromal Cell-Extracellular Vesicle Biogenesis, Alters Cargo Sorting, and Therapeutic Potency in vitro

Mesenchymal stromal cells (MSCs) are multipotent stromal cells with regenerative, immunomodulatory, and anti-inflammatory properties, making them a promising tool in cell-based therapies. Increasing evidence suggests the therapeutic effects of MSCs are largely mediated by secreted paracrine factors and extracellular vesicles (EVs), which facilitate extracellular communication by transferring bioactive molecules such as proteins, lipids, and nucleic acids to target cells. The lipid composition of EVs is critical for their stability, uptake, and functional activity. Sphingomyelinase (SMase), an enzyme that hydrolyzes sphingomyelin into ceramide, plays a key role in EV biogenesis by influencing membrane curvature allowing for invagination and budding of multivesicular bodies (MVBs). However, the impact of SMase treatment on the characteristics and therapeutic potential of MSC-derived EVs remains largely unexplored. In this study, human MSCs were cultured with SMase for 24 hours and EVs were isolated via ultracentrifugation. EV size distribution was analyzed using nanoparticle tracking analysis (NTA), microRNA (miRNA) profile was determined using RNA-sequencing, while lipidomic and proteomic profiling were assessed using mass spectrometry. Functional assays were conducted to assess changes in bioactivity. NTA revealed a shift in EV production, with a higher vesicle concentration in SMase induced MSCs compared to untreated cells. SMase treatment significantly altered MSC-EV composition, leading to increased ceramide and glycosphingolipids. In addition, the modifications in protein and miRNA EV cargo were found to be associated with pathways involving TNF-a signaling, vesicle trafficking, wound healing, and angiogenesis. Functional assays indicated greater suppression of TNF-a in activated macrophages and greater tubular network formation in HUVECS. These findings provide new insights into distinct biophysical and biochemical changes in MSC-derived EVs following SMase stimulation, potentially enhancing their therapeutic properties and may inform strategies for optimizing future EV-based therapies. Overall design: MSCs were treated with SMase for 24 hours and the miRNA profile of MSCs and their derived EVs was sequenced.