DNA nanodevice-engineered macrophages as living sensors for dual-mode in vivo monitoring of tumor-associated macrophage polarization.

Exploiting macrophages as cell-autonomous reporters of their polarization states represents a promising strategy for interrogating tumor-associated macrophage (TAM) phenotypes in cancer. Here, we develop a macrophage-based sensing platform, termed eMφ. This platform is created by engineering macrophages with a modular and multiplexable DNA origami nanodevice to report TAM polarization states within the tumor microenvironment. Upon tumor infiltration, microenvironmental cues drive macrophage polarization, triggering the engineered system to convert endogenous signals (e.g., Arg1 or iNOS mRNA) into distinct, state-specific reporter outputs. The integration of local and circulating reporters enables compartment-resolved, multiscale readouts of macrophage state. Following intravenous administration, eMφ facilitates tumor detection across multiple murine models, including B16F10 melanoma and lung metastasis, and enables precise evaluation of macrophage-reprogramming immunotherapy. Overall, this work establishes DNA nanodevice-programmed macrophages as a novel class of synthetic-living hybrid systems, paving the way for programmable and precise immune-state diagnostics and therapy.