**3. Extracellular vesicles and tumor microenvironment**

Tumor masses are composed of cancer cells and stromal cells, in which one include mesenchymal cells, fibroblasts and immune cells, and extracellular matrix (ECM) components. All these cells emit EVs and participate in the creation of a unique tumor nanoenvironment. EVs are capable of horizontal transfer of bioactive content to interact with cells in the tumor microenvironment. These interactions can include fusion of the EV with the plasmalemma of the recipient cell or endocytosis of the EVs [77]. EVs represent the bidirectional way of interaction between stromal and cancer cells as a mean to exchange information and modify the tumor microenvironment. Therefore, the content of these vesicles is of great significance in the evolution of the cancer, since it was shown to modulate the complex signaling networks that facilitate tumor progression [78].
