Using stem cells
Stem cells can divide to produce new cells, which can then divide into different cell types. They therefore have the potential to be transplanted into patients to treat medical conditions and diseaseIllness affecting plants and animals.. They could be used to replace cells that have been damaged or destroyed, eg:
- in heart disease
- in type 1 diabetesA serious disease in which the body is unable to regulate blood sugar.
- in cases of multiple sclerosisA condition, usually autoimmune, in which the myelin sheaths of the neurones of the brain and spinal cord are damaged, reducing the transmission of nerve impulses, and leading eventually to paralysis. , which can lead to paralysisThe loss of muscle function in part of the body.
- in cases of spinal cordThe part of central nervous system of a mammal which runs inside its backbone or brainThe organ of the central nervous system of mammals where vital functions are coordinated injury, that have led to paralysis
The stem cells used could be:
- embryonic stem cellA type of stem cell found in the embryo, capable of dividing into almost any cell type.
- adult stem cellA type of stem cell found in specific locations in adults. Adult stem cells can only differentiate into a limited number of related cell types.
Embryonic stem cells can differentiationWhen an unspecialised cell becomes a more specialised cell type. into a wider range of cell types, but are difficult to obtain and their use raises ethical challenges. The best source is the five-day-old embryo.
Adult stem cells will differentiate into a narrower range of cell types. bone marrowSoft tissue found inside bones that produces new blood cells. transplants are an example of adult stem cell transplant. Bone marrow cells will differentiate into different types of blood cell. Bone marrow transplants are carried out:
- in cases of blood cell cancerA disease caused by normal cells changing so that they grow and divide in an uncontrolled way. The uncontrolled growth causes a lump called a tumour to form. such as leukaemia and lymphoma
- when blood cells have been destroyed by cancer treatment
Benefits and risks associated with the use of stem cells in medicine
Stem cells have great potential in treating patients with currently untreatable conditions, growing organs for transplants, and research. But there are clinical, ethicalRelating to right and wrong, eg ethical companies are often ones that act in a responsible way. and social issues with their use. These issues will be different for growth and transplant of adult, embryonic and therapeutic cloningUsing cloning technology for medicinal purposes. One example is to use a person's DNA to clone one of their organs for use in transplanting. stem cells. They will also depend on whether the stem cells are to be used for therapy or research.
It is important to obtain a balanced view. Sometimes, there are no right or wrong answers, or even answers at all.
Some variables which would be considered when discussing stem cells include:
Clinical issues
- There is no guarantee how successful these therapies will be, for example, the use of stem cells in replacing nerve cells lost in Parkinson's disease patients.
- The current difficulty in finding suitable stem cell donors.
- The difficulty in obtaining and storing a patient's embryonic stem cells. These would have to be collected before birth - some clinics offer to store blood from the umbilical cord when a person is born.
- mutationA random and spontaneous change in the structure of a gene, chromosome or number of chromosomes. have been observed in stem cells cultured for a number of generations, and some mutated stem cells have been observed to behave like cancer cells.
- Cultured stem cells could be contaminated with viruses which would be transferred to a patient.
Ethical issues
- A source of embryonic stem cells is unused embryos produced by IVFThe letters stand for 'in vitro fertilisation'. This involves bringing the sperm and the egg together to create an embryo, which is placed into the woman's womb to increase the chance of giving birth. (in vitro fertilisation).
- For therapeutic cloning, is it right to create embryos for therapy and destroy them in the process?
- Embryos could come to be viewed as a commodity, and not as an embryo that could develop into a person.
- At what stage of its development should an embryo be regarded as, and treated as a person?
Social issues
- Educating the public about what stem cells can, and can’t do, is important.
- Whether the benefits of stem cell use outweigh the objections.
- Much of the research is being carried out by commercial clinics, so reported successes are not subject to peer review. Patients could be exploited by paying for expensive treatments and being given false hope of a cure as stem cell therapies are only in their developmental stages.
