Therapeutic cloning

Therapeutic cloning (also known as somatic cell nuclear transfer, cell nuclear replacement, research cloning, and embryo cloning) involves taking an egg (or oocyte) from which the nucleus has been removed, and replacing that nucleus with DNA from the cell of another organism. The result is an embryo with almost identical DNA to the organism.

The procedure is surrounded by controversy, and this is reflected in the language used to describe the embryo created. Some people don't like to refer to the result as an embryo, since it has not been created by fertilisation, but others think that since, given the right conditions, it could grow into a fetus and eventually a child, it doesn't seem misleading to call it an embryo.

The aim of carrying out this procedure is to obtain stem cells that are genetically matched to the donor organism. For example, if a person with Parkinson's disease donated their DNA, then it should be theoretically possible to generate embryonic stem cells that could be used to treat their condition without being rejected by the patient's immune system. No such therapies presently exist, however, and the development of the technology has been delayed as governments debate whether to ban such research.

Therapeutic cloning is currently legal for research purposes in the United Kingdom, having been incorporated into the 1990 Human Fertilisation and Embryology Act in 2001. In many other countries, the practice is banned, though laws are being debated and changed regularly. The United Nations voted on a Costa Rica bill to ban both reproductive cloning and therapeutic cloning on December 8, 2003.

Support for this procedure derives from its potential medical applications. Some opposition is based on the fact that the procedure destroys human embryos. Others feel that it instrumentalizes human life, or that it would impossible to allow therapeutic cloning while preventing reproductive cloning from occurring.