Engineered Bacterial Outer Membrane Vesicles for Tumor Diagnosis and Treatment: A Review

Bacterial outer membrane vesicles (OMVs) are spherical bilayer nanostructures that typically range from 20 to 250 nm in diameter and are secreted by Gram-negative bacteria as part of their normal growth process. These vesicles contain multiple pathogen-associated molecular patterns (PAMPs) derived from the bacterial outer membrane and periplasm, which stimulate the expression of cytokines and costimulatory molecules in immune cells, thereby promoting antigen presentation and activating systemic immunity. Moreover, OMVs can be modified by different approaches, endowing them with great potential for applications in disease treatment and diagnosis, such as imaging, antimicrobial treatment, tumor therapy, and so on. This review provides a comprehensive overview of the structural composition, biogenesis mechanisms, and genetic modification methods of OMVs. It then introduces the typical applications of engineered OMVs, such as drug delivery vehicles, adjuvants, tumor vaccines, and tracer materials. Finally, it discusses the future development and potential of OMVs.