Extracellular vesicles derived from macrophages: Current applications and prospects in tumors

Macrophages (Mφs) are significant innate immune cells that perform a variety of tasks in response to different pathogens or stimuli. They are widely engaged in the pathological processes of various diseases and can contribute to tumorigenesis, progression and metastasis by regulating the tumor microenvironment and cancer cells. They are also the basis of chemoresistance. In turn, the tumor microenvironment and the metabolism of cancer cells can limit the differentiation, polarization, mobilization and the ability of Mφs to initiate an effective anti-tumor response. Extracellular vesicles (EVs) are small vesicles released by live cells that serve as crucial mediators of intercellular cell communication as well as a potential promising drug carrier. A growing number of studies have demonstrated that Mφs-EVs are not only important mediators in the pathological processes of various diseases such as inflammatory disorders, fibrosis and cancer, but also show significant potential in immunological modulation, cancer therapy, infectious defense and tissue repair. These natural nanoparticles (NPs) derived from Mφs are believed to be pleiotropic, stable, biocompatible and low immunogenic, providing novel alternatives for cancer treatment. This review provides an update on the pathological and therapeutic roles of Mφs-EVs in cancer, as well as their potential clinical applications and prospects.