干细胞存在于人或动物的胚胎或某些组织器官中，是一类具有自我更新能力、高度增殖和多向分化潜能的细胞群体，可以分为胚胎干细胞(ES细胞)与成体干细胞。ES细胞具有全能性，可以分化成人体的各种组织细胞。成体干细胞具有多向分化潜能，可以分化为某一组织的多种细胞，如表皮 Stem cells, which are present in human or animal embryos or certain tissues and organs, are a group of cells capable of self-renewal, highly proliferating and multipotential. They can be divided into embryonic stem cells (ES cells) and adult stem cells. ES cells are pluripotent and can differentiate into various tissues of the human body. Adult stem cells have multi-directional differentiation potential, can differentiate into a variety of cells in a tissue, such as the epidermis