Artificially Modified NK Cell-Based Synergistic Immuno-Gene-Photodynamic Therapy for Cancer.

Background: The immunotherapeutic approach utilizing Natural Killer (NK) cells for cancer treatment has garnered significant interest owing to its inherent cytotoxicity, immunomodulatory properties, demonstrated safety in in vivo studies. However, multiple immunosuppressive mechanisms in the tumor microenvironment (TME) suppress the anticancer effect of NK cells in the treatment of solid tumors. Herein, a smart NK cell drug delivery system (DDS) with photo-responsive and TME-responsive properties was designed.

Methods: The NK cell DDS consists of two parts: the carrier is living NK cell with pH-low (abbreviated as NK_pH) insertion peptide on its surface, the cargo is reductive-responsive nanogel (NG) encapsulated siRNA and photosensitizer (abbreviated as SP-NG), the final carrier was abbreviated as SP-NG@ NK_pH. Firstly, pHLip helped artificially modified NK cell target and anchor onto cancer and exert the efficacy of cellular immunotherapy. Then, the strategy of combining photoactivation and bioreduction responsiveness achieved the precise release of cargos in cancer cells. Finally, the DDS combined the effect of the immunotherapy of NK cell, the gene therapy of siRNA, and the photodynamic therapy of photosensitizer.

Results: Under near-infrared laser irradiation, SP-NG@NK_pH induced an increase in reactive oxygen species (ROS) within cells, exacerbated cell membrane permeability, and allowed for rapid drug release. Within the tumor microenvironment (TME), NG exhibits highly sensitive reducibility for drug release. The SP-NG released from NK cells can be uptaken by tumor cells. When exposed to near-infrared laser irradiation, SP-NG@NK_pH demonstrates significant tumor-targeting specificity and cytotoxicity.

Discussion: The combined effect of the immunotherapy of NK cell, the gene therapy of siRNA, and the photodynamic therapy of photosensitizer obtained a stronger cancer killing effect in vitro and in vivo. Therefore, this versatile NK cell DDS exhibits a good clinical application prospect.