Therapeutic cloning is a term used to describe the creation of stem cells for use in a medical treatment for a particular individual. In fact, these cells are not used for treatments yet and would certainly not be put into a patient at present.

In practice, therapeutic cloning currently means creating an embryonic stem cell line by a technique called somatic cell nuclear transfer (SCNT). In this process, the nucleus of an adult cell from an animal is transferred into an egg cell that has had its nucleus removed. The embryo can be allowed to grow to a very early stage of development, and then used as a source of stem cells. In the future this method could provide a source of cells for therapy.

Therapeutic cloning:Somatic cell nuclear transfer can be used to create new embyronic stem cell lines.

There is no consensus on the ethical implications of therapeutic cloning.

Arguments for allowing therapeutic cloning

Arguments against allowing therapeutic cloning

The potential for huge benefits to human kind in the future outweighs any wrong-doing.

Even if destroying embryos is classed as killing, sometimes society may justify killing to save the lives of others: eg if Hitler had been assassinated, millions of lifes would probably have been saved.

Embryonic stem cell lines could be created from the cells of patients suffering from rare, complex diseases, creating a vast resource that can be used by many scientists.

Misguided individuals could attempt to implant cloned human embryos in a womans uterus to create a cloned person (known as reproductive cloning). There are laws against this in many countries, but not all.

Commercial pressures and international competition could drive scientists to conduct more and more research on embryos, which would just become a resource for researchers.

The eggs used to create embryos in this way have to be donated by women, who could be exploited for their eggs, especially in poorer countries or places with fewer legal restrictions.

The rest is here:
Embryonic stem (ES) cells - eurostemcell.org