Mesenchymal Stem Cell-Derived Extracellular Vesicles Mitigate Immune Cell Activation in an in Vitro Model of Postresuscitation Inflammation

Background: – Systemic inflammation is a key component of postcardiac arrest syndrome (PCAS) and contributes to significant morbidity and mortality after resuscitation from sudden cardiac arrest. Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) have emerged as promising immunomodulatory agents in various inflammatory conditions, including ischemia-reperfusion injury (IRI). We investigated the therapeutic potential of MSC-EVs in porcine peripheral blood mononuclear cells (PBMCs) stimulated with lipopolysaccharide (LPS) or mitochondrial DNA (mtDNA) to model immune cell activation relevant to PCAS. Methods: – Transcriptomic profiling was performed on PBMCs from swine at baseline and 4 hours after resuscitation from cardiac arrest and compared with ex vivo mtDNA-stimulated PBMCs to establish mtDNA as a PCAS-relevant pro-inflammatory stimulus. PBMCs from healthy pigs were then stimulated with 1 μg/mL mtDNA + transfection reagent or 5 μM LPS and treated with escalating concentrations of MSC-EVs. Flow cytometry, quantitative PCR, ELISA, and reactive oxygen/nitrogen species measurements were performed to assess PBMC activation. Results: – Transcriptomic profiling identified overlapping differentially expressed genes and convergent enrichment of cytosolic DNA-sensing/antiviral response pathways and cytokine/chemokine signaling programs in mtDNA-stimulated PBMCs and PBMCs collected from swine with PCAS. In mtDNA-stimulated PBMCs, MSC-EVs attenuated dendritic cell activation, reduced inflammatory cytokine gene expression and release, and decreased reactive oxygen/nitrogen species production in a concentration-dependent manner. MSC-EVs also produced concentration-dependent reductions in LPS-induced granulocyte activation and expression of IFNα, IL-1β, and TNFα. Conclusions: – MSC-EVs exert immunomodulatory effects against mtDNA- and LPS-mediated PBMC activation, supporting further investigation as a cell-free therapeutic strategy to target immune activation in PCAS and other acute inflammatory conditions.