Berberine-loaded human dental pulp stem cells exosomes potentiate antimicrobial photodynamic therapy against Porphyromonas gingivalis biofilms

• Berberine-loaded human dental pulp stem cell-derived exosomes (Ber@hDPSCs-Exos) inhibited Porphyromonas gingivalis biofilm formation with a minimum biofilm inhibitory concentration (MBIC) of 125 µg/mL. • The 405 nm diode laser achieved a minimum biofilm inhibitory dose (MBID) of 240 seconds, reducing biofilm biomass significantly. • Antimicrobial photodynamic therapy (aPDT) using 31.2 µg/mL Ber@hDPSCs-Exos and 60 seconds irradiation markedly decreased P. gingivalis biofilm optical density to approximately 2.44. • Sub-MBIC aPDT downregulated the fimA virulence gene expression in P. gingivalis by 3.1-fold. Periodontitis, a prevalent infectious disease driven by polymicrobial dental plaque biofilms, is associated with systemic health risks. Porphyromonas gingivalis acts as a keystone pathogen within these biofilms, with the fimA gene encoding the major fimbrial subunit FimA serving as a key virulence factor facilitating bacterial adhesion and biofilm formation, critical for persistence and periodontal destruction. Berberine, a benzylisoquinoline alkaloid with antimicrobial properties, is limited by poor solubility and bioavailability. This study explores antimicrobial photodynamic therapy (aPDT) using berberine-loaded human dental pulp stem cell-derived exosomes (Ber@hDPSCs-Exos) to enhance anti-biofilm efficacy against P. gingivalis. Exosomes were isolated from hDPSCs and characterized by transmission electron microscopy, flow cytometry (CD81 expression), and Bradford assay. Berberine was loaded into exosomes via ultrasonication, with encapsulation efficiency assessed by UV spectrophotometry. The minimum biofilm inhibitory concentration (MBIC) of Ber@hDPSCs-Exos, minimum biofilm inhibitory dose (MBID) of a 405 nm diode laser, and MBIC of aPDT were determined against P. gingivalis biofilms using colorimetric assays. The expression of the fimA virulence gene was evaluated via quantitative real-time PCR. Statistical analysis was performed using one-way ANOVA (P < 0.05). hDPSCs-Exos exhibited spherical morphology, high CD81 expression (80.3%), and a protein concentration of 460.75 µg/mL. Berberine encapsulation efficiency was 74.9%. Ber@hDPSCs-Exos inhibited P. gingivalis biofilm formation with an MBIC of 125 µg/mL, while the diode laser MBID was 240 s (103.9 J/cm²). aPDT with 31.2 µg/mL Ber@hDPSCs-Exos and 60 s irradiation significantly reduced biofilm biomass (OD570 nm ∼2.44). Sub-MBIC aPDT (15.6 µg/mL, 120 s) downregulated fimA expression by 3.1-fold (P < 0.05). Ber@hDPSCs-Exos-based aPDT effectively inhibits P. gingivalis biofilm formation and reduces fimA expression, offering a promising adjunctive treatment for periodontitis management. Further in vivo studies are required to confirm the clinical potential of this approach.