Selenium nanoparticles activate selenoproteins to mitigate septic lung injury through miR-20b-mediated RORγt/STAT3/Th17 axis inhibition and enhanced mitochondrial transfer in BMSCs.

Sepsis-induced acute lung injury (ALI) remains a critical clinical challenge with complex inflammatory pathogenesis. While bone marrow mesenchymal stem cells (BMSCs) demonstrate therapeutic potential through anti-inflammatory and cytoprotective effects, their age-related functional decline limits clinical utility. This study developed chitosan-functionalized selenium nanoparticles (SeNPs@CS, 100 nm) to rejuvenate BMSCs through miR-20b-mediated selenoprotein biosynthesis. Mechanistic investigations revealed that SeNPs@CS-treated BMSCs exhibited enhanced mitochondrial transfer capacity, delivering functional mitochondria to damaged alveolar epithelial cells (AECII) for cellular repair. Concurrently, miR-20b upregulation suppressed the RORγt/STAT3/Th17 axis, reducing pro-inflammatory Th17 cell differentiation in CD4(+) T lymphocytes. The dual-target mechanism integrates immunomodulation via Th17 pathway inhibition with mitochondrial rejuvenation therapy, representing a paradigm-shifting approach for ALI management. These engineered BMSCs mitigated inflammatory markers in murine models, demonstrating superior efficacy to conventional BMSC therapies. Our findings establish SeNPs@CS-modified BMSCs as a novel therapeutic platform combining nanotechnology-enhanced stem cell engineering with precision immunometabolic regulation, providing new avenues for the treatment of sepsis-induced ALI.