Tumor-derived extracellular vesicles as messengers of natural products in cancer treatment

Extracellular vesicles (EVs) are kinds of two-layer vesicles secreted by cells. They play significant roles in mediating component exchange between cells, signal transduction, and pathological development. Among them, the tumor-derived EVs (TDEVs) are found related to the tumor microenvironment and cancer development. TDEVs can be designed as a natural drug carrier with high tumor targeting and permeability. In recent years, drug delivery systems (DDS) based on TDEVs for cancer treatments have received considerable attention. In this review, the biological characteristics of TDEVs are introduced, especially the effect on the tumor. Furthermore, the various approaches to constructing DDS based on TDEVs are summarized. Then we listed examples of TDEVs successfully constructing treatment systems. The use of chemical drugs, biological drugs, and engineered drugs as encapsulated drugs are respectively introduced, particularly the application progress of active ingredients in traditional Chinese medicine. Finally, this article introduces the latest clinical research progress, especially the marketed preparations and challenges of clinical application of TDEVs.