Gàn stem cells are pluripotent cells with self-renewal ability. Under certain conditions, it can differentiate into a variety of functional cells. Stem cells can be divided into embryonic stem cells (ES cells) and adult stem cells (somatic stem cells) according to their developmental stages. According to their developmental potential, stem cells can be divided into three categories: totipotent stem cells (TSC), multipotent stem cells and unipotent stem cell. Stem cells are immature cells, which have the potential function of regenerating various tissues and organs and the human body. It is called "universal cell" in the medical field.