Extracellular vesicles (EVs) are the substances that are released by most types of cells and have an important role in cell to cell communication. Among the most highly researched EVs are exosome. Recent studies show that exosomes derived from cells have different roles and targets. Many studies show that exosome can efficiently deliver many different kinds of cargo to the target cell. Therefore, they are often used to deliver therapeutic cargo for treatment. The exosomes that have been used include both natural ones and those that have been modified with other substances to increase the delivery ability. This article provides a review of both exosomes derived from various cells and modified exosome and their ability in delivering the many kinds of cargo to the target cell.

Amino acids are basic nutrients for immune cells during organ development, tissue homeostasis, and the immune response. Regarding metabolic reprogramming in the tumor microenvironment, dysregulation of amino acid consumption in immune cells is an important underlying mechanism leading to impaired anti-tumor immunity. Emerging studies have revealed that altered amino acid metabolism is tightly linked to tumor outgrowth, metastasis, and therapeutic resistance through governing the fate of various immune cells. During these processes, the concentration of free amino acids, their membrane bound transporters, key metabolic enzymes, and sensors such as mTOR and GCN2 play critical roles in controlling immune cell differentiation and function. As such, anti-cancer immune responses could be enhanced by supplement of specific essential amino acids, or targeting the metabolic enzymes or their sensors, thereby developing novel adjuvant immune therapeutic modalities. To further dissect metabolic regulation of anti-tumor immunity, this review summarizes the regulatory mechanisms governing reprogramming of amino acid metabolism and their effects on the phenotypes and functions of tumor-infiltrating immune cells to propose novel approaches that could be exploited to rewire amino acid metabolism and enhance cancer immunotherapy.