Hypericin-loaded small extracellular vesicles increase photodynamic therapy and remodel miRNA–mRNA axes in AGS gastric cancer cells

Gastric cancer remains a cause of cancer mortality, and there is a need for locally controllable therapies that limit systemic toxicity and overcome heterogeneous responses. Photodynamic therapy (PDT) is attractive, yet efficacy is constrained by limited intracellular availability of photosensitizers. We tested whether small extracellular vesicles (sEVs) enhance hypericin (HYP) delivery and PDT responses in AGS cells, and whether cytotoxicity aligns with transcript and epigenetic remodeling. Human sEVs were loaded with HYP by probe sonication and characterized by DLS/ELS, TEM, and CD9/CD63/CD81 flow profiling. Cells were assigned to untreated, light-only, sEV-only (+ light), free HYP (dark), free HYP + PDT, sEV–HYP (dark), or sEV–HYP + PDT; irradiation used 590 nm (3 J/cm²). sEV–HYP + PDT left-shifted dose–response and reduced IC₅₀ at 24 h (9.8 vs. 12.9 µg/mL) and 48 h (5.1 vs. 8.9 µg/mL). sEV delivery accelerated intracellular deposition: at 4 h, HYP + cells reached 91.0% versus 68.0%, mean fluorescence intensity (MFI) increased, and HPLC confirmed higher intracellular hypericin (0.63 vs. 0.36 µg/mg protein). Enhanced deposition coincided with stronger ROS generation (3.85-fold vs. 3.10-fold; p = 0.012) and higher apoptosis (45.3% vs. 41.8%); ROS correlated with apoptosis ( r = 0.992, p < 0.001). PDT also remodeled miR-21/PTEN and miR-34a/BCL2 axes and was associated with promoter methylation shifts and histone mark changes at PTEN and BCL2. Thus, sEV-mediated delivery improves intracellular HYP availability and amplifies PDT efficacy with coordinated regulatory signatures in vitro.