Integrating oxygen-boosted sonodynamic therapy and ferroptosis via engineered exosomes for effective cancer treatment

Rationale: Ferroptosis and sonodynamic therapy (SDT) are both promising therapeutic modalities, but their clinical application remains challenging due to the hypoxic tumor microenvironment and limited supply of polyunsaturated fatty acids. Developing an agent with oxygen-enhanced SDT and increased ferroptosis sensitivity is crucial for advancing tumor therapy. Methods: In this study, catalase (Cat) and Acyl-CoA synthetase long-chain family member 4 (ACSL4) highly expressed 4T1 cells were constructed via lentivirus transfection. Cat and ACSL4 enriched exosomes (EXO@CA) were then extracted and loaded with the sonosensitizer tetrakis (4-carboxyphenyl) porphyrin (TCPP) through electroporation to create engineered exosomes (EXO@CAT). We evaluated the ability of EXO@CAT to generate oxygen in a hydrogen peroxide environment and investigated its effect on motion profiles and permeability of EXO@CAT. The in vitro antitumor activity was assessed via cytotoxicity, ROS levels, live/dead staining, and apoptosis, with ferroptosis biomarkers confirming ferroptosis activation. We also evaluated the in vivo anticancer efficacy of EXO@CAT by tumor growth analysis and histological and immunohistochemical staining in mouse models bearing breast tumor. Results: EXO@CAT harnesses ultrasound stimulation to facilitate oxygen-enriched SDT, demonstrating significant capacity for singlet oxygen (¹O₂) generating, which promotes the accumulation of lipid peroxidation (LPO), ultimately leading to the induction of ferroptosis. Concurrently, ACSL4 released from EXO@CAT also increases LPO accumulation by modifying cellular lipid composition, thereby enhancing cellular sensitivity to ferroptosis. Moreover, both in vitro and in vivo experiments demonstrate that the homologous targeting ability of EXO@CAT enables its efficient accumulation in tumor tissues, and the oxygen generation catalyzed by Cat not only alleviates tumor hypoxia but also facilitates the penetration of EXO@CAT into deeper layers of tumor tissue. Conclusions: EXO@CAT combines endogenous proteins, which are prone to inactivation, with an exogenous sonosensitizer, allowing synergistic anticancer treatment of both ferroptosis and SDT with improved efficacy.