A novel method to encapsulate polydeoxyribonucleotides extracted from trout into exosomes and applications in skin recovery.

Polydeoxyribonucleotide (PDRN), a DNA polymer derived from salmonid tissue, is widely used in regenerative dermatology but its topical application is limited by poor stability and delivery efficiency. Exosomes, nanoscale vesicles with high cellular uptake and low immunogenicity, offer a promising platform for nucleic acid protection and targeted delivery. In this study, we developed an electroporation-based method to load fragmented PDRN into HaCaT-derived exosomes for enhanced skin regeneration. PDRN was extracted, ultrasonically fragmented to < 200 bp, and encapsulated into exosomes using optimized electroporation parameters. Exosome integrity and size distribution were confirmed by nanoparticle tracking analysis and transmission electron microscopy. Functional activity was evaluated using wound-healing scratch assays and RT-qPCR of pro-inflammatory (TNF-α, IL-6, IL-1β) and regeneration-associated (COL1A1, MMP2) genes. PDRN-loaded exosomes significantly accelerated wound closure and exhibited superior anti-inflammatory effects compared with exosome-only and PDRN-only controls in a dose- and time-dependent manner. Pro-inflammatory cytokine mRNA levels were markedly reduced, while COL1A1 and MMP2 expression were significantly increased at 200 ng, indicating activation of extracellular matrix remodeling pathways. These findings demonstrate that exosome-encapsulated PDRN delivery via electroporation enhances DNA stability and regenerative efficacy without compromising vesicle structure, highlighting its potential as an advanced cosmetic and therapeutic platform for skin repair. Therefore, clinical trials are needed to develop cosmetics or therapeutics using exosome-encapsulated PDRN in the future.