Currently, it is known that various abnormal cells including various normal cells and cancer cells form and secrete vesicles having a lipid bilayer membrane, and these membranous vesicles are called extracellular vesicles. Extracellular vesicles are classified into three types: apoptotic bodies, microvesicles, and exosomes. In this paper, we focus on exosomes, which have recently been attracting attention as a new cell-cell communication mechanism, and their formation mechanism. The isolation and purification methods are outlined, mainly regarding their usefulness and future potential in the early diagnosis of cancer, based on the cytobiological characteristics of exosomes.
