Tailoring Vascular-Immune Homeostasis via Manganese-DNA Complex-Armed Immunogenic Extracellular Vesicles for Pancreatic Cancer Immunotherapy.

Harnessing the cGAS-STING DNA sensing pathway in dendritic cells (DCs) to enhance anti-tumor immunity in immunosuppressive pancreatic tumors remains a significant challenge. While manganese (Mn2+) enhances cGAS sensitivity to DNA, the precise mechanisms and potential of Mn-DNA complexes in this process are unclear. Here, this work introduces a strategy to encapsulate Mn-DNA complexes into DC-derived immunogenic extracellular vesicle (EVDC@Mn-DNA) to trigger robust anti-tumor immunity. This work shows that Mn2+ induces tumor cell-DNA transition to Z-DNA, strengthening cGAS binding and promoting its phase condensation for optimal activation in DCs. Using this newly developed Raft-Ultra method, this work engineers immunogenic EVs derived from tumor cell lysate-pulsed DCs, loaded with Mn-DNA complexes (EVDC@Mn-DNA). These EVs efficiently deliver Mn-DNA complexes to DCs, activating the cGAS-STING pathway both in vitro and in vivo. In animal models, EVDC@Mn-DNA administration enhances vascular function, as evidenced by increased blood flow and perfusion, improved anti-PD-L1 delivery, reduced hypoxia, and elevated endothelial cell-ICAM1 expression, which facilitates T cell adhesion. This approach expands the intratumoral population of activated DCs and T cells and promotes the formation of larger tertiary lymphoid structures, ultimately suppressing orthotopic pancreatic tumor growth. Overall, this EVDC@Mn-DNA strategy reprograms intratumoral DCs, restores vascular-immune homeostasis, and potentiates anti-tumor immunity in pancreatic cancer.