Some diseases can be treated with antibiotics, but not all can be cured. Vaccinations allow protection against specific diseases, but the level of protection depends on the amount of people vaccinated.
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 disease. They could be used to replace cells that have been damaged or destroyed, eg:
Embryonic stem cells can differentiate 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 marrow 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 cancer 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, ethical and social issues with their use. These issues will be different for growth and transplant of adult, embryonic and therapeutically-cloned 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:
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.
Mutations 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.
A source of embryonic stem cells is unused embryos produced by IVF (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?
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.