Engineered M2 macrophage-derived vesicles deliver DNase I for cfDNA clearance and multi-organ protection in sepsis.

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. Despite advances in critical care, it remains a major global health challenge, highlighting the urgent need for novel therapeutic approaches. Elevated plasma cell-free DNA (cfDNA) has emerged as a critical driver of inflammation and tissue injury in sepsis. To neutralize its detrimental effects, DNase I can enzymatically degrade circulating cfDNA; however, the clinical application of native DNase I is limited by its rapid degradation and short circulation half-life. Here, we developed a bioengineered delivery system by encapsulating DNase I within M2 macrophage-derived extracellular vesicles (M2-EVs@DNase I), which possess intrinsic targeting ability, high biocompatibility, and low immunogenicity. In a cecal ligation and puncture (CLP)-induced sepsis model, administration of M2-EVs@DNase I significantly reduced circulating cfDNA levels by approximately 60% and suppressed TLR9 activation by about 49%. These effects were accompanied by a shift in macrophage polarization toward an anti-inflammatory M2 phenotype, reduced neutrophil activation, and significant attenuation of lung and kidney injury. Furthermore, treatment with M2-EVs@DNase I significantly improved biochemical indicators of organ function, including ALT, AST, UREA, and CRE levels. Together, these findings demonstrate that M2-EVs@DNase I effectively degrades pathogenic cfDNA and mitigates inflammatory responses, thereby protecting against sepsis-induced multi-organ injury. This study highlights the pathogenic significance of cfDNA in sepsis and introduces M2-EVs@DNase I as a promising biomimetic nanotherapeutic platform for sepsis treatment.