Stem Cells

• A stem cell is an undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type, and from which certain other cells can arise from differentiation.
• Stem cells from human embryos can be cloned and made to differentiate into most different types of human cells. Stem cells from adult bone marrow can form many types of cells including blood cells. Meristem tissue in plants can differentiate into any type of plant cell throughout the life of the plant.
• Treatment with stem cells may be able to help conditions such as diabetes and paralysis.
• In therapeutic cloning an embryo is produced with the same genes as the patient. Stem cells from the embryo are not rejected by the patient's body so they may be used for medical treatment. The use of stem cells has potential risks such as transfer or viral infection, and some people have ethical or religious objections. Stem cells from meristems in plants can be used to produce clones of plants quickly and economically.
• • Rare species can be cloned to protect from extinction.
  • Crop plants with special features such as disease resistance can be cloned to produce large numbers of identical plants for farmers.
• Some cells are undifferentiated - they have not yet become specialised
• Undifferentiated cells can divide to make different types of cells. They are called stem cells.
• Stem cells are found in human embryos, in the umbilical cord of a new born baby, and in some organs and tissues
• Stem cells from human embryos are called embryonic stem cells and can make all types of cells
• Adult stem cells are found in some organs and tissues, e.g. bone marrow. They can only make certain types of cells and their capacity to divide is limited.
• Stem cells may be very useful in treating conditions where cells are damaged or not working properly, such as diabetes and paralysis.
• Stem cells could be used to replace damaged cells
• Therapeutic cloning involves creating embryonic stem cells from an adult. A nucleus from the patient is added to an egg that has had its nucleus removed. The egg is stimulated to divide, becoming an embryo. The embryo is a clone of the patient with the same genes. The stem cells in the embryo will not be rejected by the patient and could help treat the patient's conditions.
• The use of embryonic stem cells has to be evaluated by weighing up the benefits, risks and social and ethical issues.
• Benefits include saving life and reducing suffering, however:

  • risk of transfer of viral infection
  • some people may object due to religious or ethical resons
• In plants, stem cells are found in special areas called meristems.
• Meristems allow plants to make new cells for growth
• The stem cells can be used to produce clones of plants quickly. This could be useful for a number of reasons:

  • rare species can be clones to protect them from extinction
  • large numbers of identical crop plants with special features, such as disease resistance, can be made
• Although there are adult stem cells all over the body, they are very difficult to find and isolate.