Stem cells are undifferentiated cells that can:
• divide by mitosis again and again to produce more stem cells (self-renewal)
• differentiate into specialised cell types.Most specialised cells cannot divide, so stem cells are needed to form an organism during development and, later, to replace cells that are worn out or damaged.Potency
Stem cells differ in how many types of cell they can become. This is called their potency.
• Totipotent stem cells can differentiate into any type of cell, including the cells of the placenta and other extra-embryonic tissues. They are found only in the very early embryo, up to about the 8-cell stage.
• Pluripotent stem cells can differentiate into any type of cell in the body, but not placenta cells. They are found in the inner cell mass of the blastocyst.
• Multipotent stem cells can differentiate into a limited range of related cell types. For example, stem cells in bone marrow can form the different types of blood cell.
• Unipotent stem cells can only form one type of cell, but can still self-renew. An example is the stem cells in the skin that produce skin cells.As an embryo develops, its cells gradually lose potency.
Why stem cells are important in medicine
Because they can divide and differentiate, stem cells could be used to replace cells lost through disease or injury, for example nerve cells in Parkinson's disease or insulin-secreting cells in type 1 diabetes. Bone marrow transplants, which contain blood stem cells, are already used to treat leukaemia. Stem cells can also be used to study how cells develop and to test new drugs.
• divide by mitosis again and again to produce more stem cells (self-renewal)
• differentiate into specialised cell types.Most specialised cells cannot divide, so stem cells are needed to form an organism during development and, later, to replace cells that are worn out or damaged.Potency
Stem cells differ in how many types of cell they can become. This is called their potency.
• Totipotent stem cells can differentiate into any type of cell, including the cells of the placenta and other extra-embryonic tissues. They are found only in the very early embryo, up to about the 8-cell stage.
• Pluripotent stem cells can differentiate into any type of cell in the body, but not placenta cells. They are found in the inner cell mass of the blastocyst.
• Multipotent stem cells can differentiate into a limited range of related cell types. For example, stem cells in bone marrow can form the different types of blood cell.
• Unipotent stem cells can only form one type of cell, but can still self-renew. An example is the stem cells in the skin that produce skin cells.As an embryo develops, its cells gradually lose potency.
Why stem cells are important in medicineBecause they can divide and differentiate, stem cells could be used to replace cells lost through disease or injury, for example nerve cells in Parkinson's disease or insulin-secreting cells in type 1 diabetes. Bone marrow transplants, which contain blood stem cells, are already used to treat leukaemia. Stem cells can also be used to study how cells develop and to test new drugs.