Mesenchymal stem cell-driven activatable photosensitizers for precision photodynamic oncotherapy.

Precise targeting with minimal side effects is of particular interest for personalized medicine, although it remains a challenge. Herein, we demonstrate precision photodynamic therapy (PDT) utilizing human mesenchymal stem cells (MSCs) as cellular vehicles to deliver a new activatable photosensitizer (PcS). In vivo real-time optical imaging tests indicated that PcS-loaded MSCs possess excellent tumor-homing properties. More importantly, dye transfer assays confirm that MSCs precisely transfer PcS into human colon cancer cells (HCT116) via the "bystander effect." Upon localized light irradiation, the growth of intraperitoneal xenograft tumors was significantly inhibited by the photodynamic effect. These findings represent a promising strategy for precise oncotherapy.