Therapeutic cloning
Transplanting stem cells
A type of stem cell found in specific locations in adults. Adult stem cells can only differentiate into a limited number of related cell types.Surgical procedure in which a tissue or organ is replaced. could use a patient's own stem cells or be from a donor. Those that use the patient鈥檚 own stem cells would be genetically identical and would not be rejected by the patient's immune system.
Those from a donor would not be genetically identical. Fewer complications would arise if the stem cells came from a close member of the family. Alternatively, donor cells could come from a person with closely-matched tissue types.
Therapeutic cloning
Using cloning technology for medicinal purposes. One example is to use a person's DNA to clone one of their organs for use in transplanting. could produce stem cells with the same genetic make-up as the patient.
The technique involves the transfer of the nucleus from a cell of the patient, to an The female reproductive cell. whose The nucleus controls what happens inside the cell. Chromosomes are structures found in the nucleus of most cells. The plural of nucleus is nuclei. has been removed.
Stem cells produced in this way could be transferred to the patient. Although human stem cells have been produced in this way, and used in research, there is no evidence that, as yet, they have been used to treat anyone.
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, Relating 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 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:
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鈥檚 disease patients.
- The current difficulty in finding suitable stem cell donors.
- The difficulty in obtaining and storing a patient鈥檚 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.
Ethical issues
- A source of embryonic stem cells is unused embryos produced by in vitro fertilisation (IVF)
- 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.