Stem cells

• Embryonic stem cells can turn into any type of cell
• Differentiation is the process by which a cell changes to become specialised for its job
• Undifferentiated cells, called stem cells, can divide to produce lots more undifferentiated cells. They can differentiate into different types of cell, depending on what instructions they're given
• Stem cells are found in early human embryos. Doctors and researchers are interested in them because they have the potential to turn into any kind of cell at all
• All the different types of cell found in a human being have to come from those few cells in the early embryo
• Adults also have stem cells, but they're only found in certain places, like bone marrow
• Unlike embryonic stem cells, adult stem cells can't turn into any cell type at all, only certain ones such as blood cells
• Stem cells from embryos and bone marrow can be grown in a lab to produce clones (genetically identical cells) and made to differentiate into specialised cells to use in medicine or research
• Stem cells may be able to cure amny diseases
• Medicine already uses adult stem cells to cure disease. E.g. stem cells transferred from the bone marrow of a healthy person can replace faulty cells in sick people - you could make insulin-producing cells for people with diabetes, nerve cells for people paralysed by spinal injuries...
• In atype of cloning, called therapeutic cloning, an embryo could be made to have the same genetic information as the patient. This means that the stem cells produced from it would also contain the same genes and so wouldn't be rejected by the patient's body if used to replace faulty cells
• However, there are risks involved in using stem cells in medicine. E.g. stem cells grown in the lab may come contaminated with a virus which could be passed on to the patient and make them more sick
• Some people are against stem cell research because they feel that human embryos shouldn't be used for experiments since each one is a potential human life. Others think that curing existing patients who are suffering is more important than the rights of embryos
• They argue that embryos used in research are usually unwanted ones from fertility clinics which, if they weren't used for research, would probably just be destroyed
• Campaigners for the rights of embryos feel that scientists should concentrate more on finding and developing other sources of stem cells, so people can be helped without having to use embryos
• In some countries stem cell research is banned. It's allowed in the UK as long as it follows strict guidelines