Bacteria‐Derived Extracellular Vesicle as A “Trojan Horse” for Selective M1 Macrophage‐Targeting in A Multi‐Cellular Entanglement Environment

Abstract The temporary transition of macrophages from a pro‐inflammatory macrophages (M1) to an anti‐inflammatory macrophages (M2) is crucial for tissue repair and regeneration processes. Selectively targeting M1 macrophages is preferred to modulate inflammatory responses. However, macrophage populations are inherently heterogeneous, and the competitive phagocytosis of nanoparticles (NPs) by these two subtypes has not been thoroughly investigated. This study establishes a 3D cell co‐culture system to evaluate the competitive phagocytosis of M1‐targeting NPs under dynamic fluidic flow conditions. Bacterial outer membrane vesicles (OMVs) are utilized as a “trojan horse” to decorate gold nanocage (AuNC), creating hybrid NPs (AuNC‐OM) capable of selectively targeting M1 macrophages. It is noted that the selective uptake of AuNC‐OM by M1 macrophages is mediated through phagocytosis‐related receptors CD64 and CD14, which are highly expressed on the M1 macrophage surfaces. Furthermore, the study demonstrates that AuNC‐OM selectively targets M1 macrophages without affecting the phagocytosis of M2 macrophages. Once internalized, the nanoparticles release anti‐inflammatory drugs, effectively reversing the inflammation. The release of dexmedetomidine from AuNC‐OM protects against lipopolysaccharide (LPS)‐induced bone resorption in a mouse model. This study presents a novel system for accurately assessing the M1 macrophage‐targeting capabilities and introduces an innovative strategy for M1 macrophage‐targeted therapy.