Inflammatory Preconditioning Reprograms Mesenchymal Stromal Cell-Derived Extracellular Vesicles into Distinct...

Mesenchymal stromal cell-derived extracellular vesicles (MSC-EVs) are emerging as potent cell-free mediators of tissue repair, whose composition and function can be tuned by the cellular microenvironment. Although inflammatory cues modulate mesenchymal stromal cell (MSC) behavior, how defined preconditioning strategies program extracellular vesicle (EV) functional outputs remains incompletely understood. Here, we systematically evaluated how priming bone marrow-derived MSCs with interferon-gamma/tumor necrosis factor-alpha (I/T) or lipopolysaccharide (LPS) generates EV populations with distinct immunomodulatory and regenerative properties. Using a murine full-thickness wound model, we performed an integrative analysis of biodistribution, immune response, and extracellular matrix (ECM) remodeling, complemented by single-cell, transcriptomic, and proteomic profiling. All EV populations were retained at the wound site following subcutaneous delivery and supported wound contraction; however, they drove distinct, treatment-specific repair trajectories. I/T-EVs promoted a coordinated regenerative response characterized by balanced macrophage (MΦ) activation, controlled immune modulation, and efficient resolution of inflammation, resulting in organized ECM remodeling. In contrast, LPS-EVs induced a more pro-inflammatory response, accelerating wound contraction and promoting compensatory matrix stiffening with reduced structural coordination. Control EVs primarily facilitated early immune resolution with limited induction of regenerative remodeling pathways. Proteomic profiling of EVs identified enrichment of proteins associated with insulin-like growth factor signaling, MΦ recruitment, and ECM remodeling, consistent with in vivo protein expression patterns and linking EV cargo to functional outcomes. These findings demonstrate that preconditioning does not uniformly enhance EV efficacy but instead selectively programs distinct MSC-EV functional states, establishing EV preconditioning as a tunable strategy for engineering cell-free therapeutics with predictable and context-specific therapeutic outcomes.