Advances in microbial extracellular vesicles: synthetic biology platforms and medical applications

Extracellular vesicles (EVs), typically ranging from 20 to 400 nanometers in diameter, are membrane-bound structures released into the extracellular environment by bacteria via specific secretion mechanisms. Consequently, these vesicles play a crucial role in bacterial physiological regulation and communication with hosts. Compared with EVs derived from plants and animals, Microbial extracellular vesicles (MEVs) offer distinct advantages, including lower production costs, higher yields, and greater abundance. This review outlines the biogenesis and release mechanisms of MEVs, and highlights how synthetic biology tools and platforms can be leveraged to engineer these vesicles, such as enhancing their production, modifying their cargo, and tailoring their surface properties. Furthermore, this article examines the promising biomedical applications of engineered MEVs, including targeted drug delivery, immune and inflammatory modulation, the discovery of disease biomarkers and therapeutic development. However, clinical translation of MEVs faces considerable challenges, primarily due to the lack of standardized, universally applicable isolation and purification protocols. This review therefore summarises contemporary extraction methods, functional characteristics and applications of MEVs alongside examples of recent MEV modifications. Ultimately, this work aims to bridge existing knowledge gaps and facilitate the development of MEV-based therapeutic strategies.