This technique is also known as somatic cell nuclear transfer or research cloning. Scientists are keen to remove the link in the public mind between this developing technique and adult cell cloning, because the intention in therapeutic cloning is NOT to produce a new animal or plant. The hope instead is to produce pluripotent stem cells which can in turn develop into new tissues or organs for people who are seriously ill.

So many people suffer severe disability and even die because various parts of their body stop working properly. From the sugar-balance problems of diabetes to the tremor, rigidity and loss of control of Parkinson’s disease; from the life-threatening shock of a heart attack to the horror of paralysis due to spinal injuries, there are literally millions of people who could benefit if it was possible to replace body parts which no longer work properly.

Therapeutic cloning involves using cells from an individual to produce a cloned early embryo which is then used as a source of embryonic stem cells. As it becomes possible to control the development of these stem cells into specific cell types, tissues and organs, it should be possible to grow new nerves cells, muscle cells and even new kidneys and hearts for people who desperately need them. What is more, because the patient donates the original adult cells, there will be a perfect DNA match with the new healthy tissue when it is introduced – so there will be no rejection problems.

An adult cell is taken from the patient and the nucleus is removed. At the same time the nucleus is taken out of a donated ovum, and the adult cell nucleus and the empty ovum are combined. A mild electric shock stimulates embryonic development to begin. Once a ball of cells has developed, as many embryonic stem cells as possible are harvested, destroying the embryo. The harvested stem cells can then be stimulated to produce whatever tissue is needed. Click on the image to open a larger version of it in a new page

This technique still needs a great deal of development, not least because scientists have still not unravelled the secrets of directing stem cells to form exactly the tissue they want. Therapeutic cloning seems to have enormous medical potential, but there are many ethical issues surrounding it – not least because it involves the use of human ova and the formation of an early embryo which is then destroyed. (See cloning people – fact or fantasy?)