Phospholipids in small extracellular vesicles: emerging regulators of neurodegenerative diseases and cancer

Small extracellular vesicles (sEVs) are generated by almost all cell types. They have a bilayer membrane structure that is similar to cell membranes. Thus, the phospholipids contained in sEVs are the main components of cell membranes and function as structural support elements. However, as in-depth research on sEV membrane components is conducted, some phospholipids have been found to participate in cellular biological processes and function as targets for cell-cell communication. Currently, sEVs are being developed as part of drug delivery systems and diagnostic factors for various diseases, especially neurodegenerative diseases and cancer. An understanding of the physiological and pathological roles of sEV phospholipids in cellular processes is essential for their future medical application. In this review, the authors discuss phospholipid components in sEVs of different origins and summarize the roles of phospholipids in sEV biogenesis. The authors further collect the current knowledge on the functional roles of sEV phospholipids in cell-cell communication and bioactivities as signals regulating neurodegenerative diseases and cancer and the possibility of using sEV phospholipids as biomarkers or in drug delivery systems for cancer diagnosis and treatment. Knowledge of sEV phospholipids is important to help us identify directions for future studies.