Extracellular vesicles (EVs) are crucial for facilitating intercellular communication, promoting cell migration, and orchestrating the immune response. Recently, EVs can diagnose and treat tumors. EVs can be measured as biomarkers to provide information about the type of disease and therapeutic efficacy. Furthermore, EVs with lower immunogenicity and better biocompatibility are natural carriers of chemicals and gene drugs. Herein, we review the molecular composition, biogenesis, and separation methods of EVs. We also highlight the important role of EVs from different origins as biomarkers and drug delivery systems in tumor therapy. Finally, we provide deep insights into how EVs play a role in reversing the immunosuppressive microenvironment.

Plant-derived extracellular vesicles (PDEVs), describe a group of nanoparticles released by plants. These particles are characterized by a lipid bilayer structure containing various proteins, lipids, nucleic acids, and unique metabolites. Although the study on PDEVs is relatively new, having only been around for ten years, they have shown promising development prospects in both basic research and clinical transformation areas. Evidence suggests that PDEVs have excellent application prospects in regulating inflammation and treating tumors. Their distinctive, vesicle-mimicking architecture and stellar biocompatibility render them prime candidates for ferrying various anti-cancer agents, including RNA, proteins, and conventional chemotherapy drugs. Increasingly, studies have shown that PDEVs can be engineered as an innovative platform for combination cancer immunotherapy. Consequently, this paper provides an extensive summary of current developments in engineering methods and strategies for PDEVs in cancer treatment and combined cancer immune therapeutics. The essential characteristics of PDEVs, including the biogenesis process and components, as well as their anti-tumor activity and mechanism, are summarized. Finally, the in vivo safety of PDEVs as delivery vectors and the challenges of scale-up production and clinical transformation are discussed.