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What are Stem Cells?

  • Last modified date:
    16 December 2003

Stem cells are the very early cells that can develop into almost all other types of cell and tissue. They occur in the early (5-day) embryo when it is a tiny ball of about 100 cells before it implants in the uterus (embryonic stem cells or "ES cells"). They also occur in significant numbers in some tissues in the developing fetus and in cord blood at birth. They can also be found in some adult tissue, e.g. bone marrow, but they are difficult to isolate, being present in very small numbers.

Because of their ability to differentiate into so many different cells and tissues, stem cells hold out exciting prospects for the development of new cellular based treatments.

The hope is that tissues derived from stem cells will be used to develop treatments for diseases and injuries currently incurable. The repair of spinal cord injuries and of heart tissue damaged after a heart attack are possibilities. Diseases such as Parkinson's and diabetes are also candidates for stem cell based treatments.

Most ES cell research will be done using cells derived from IVF embryos donated by gamete donors for research when they are not needed for infertility treatment. Over 48,000 embryos were donated for research in this way between 1991 and 1998 in the UK.

Stem cell research

The House of Lords Select Committee on Stem Cell Research was established in January 2001 and reported on 27 February 2002. The Committee endorsed the Government's approach and concluded that embryonic stem cell research should continue under the existing strict controls operated by the Human Fertilisation and Embryology Authority.

The Select Committee also endorsed the action taken by the Government last November to introduce a legal ban preventing anyone in the UK attempting to clone a child and has called on the Government to assist international initiatives to obtain a global ban on reproductive cloning. We are doing this through the United Nations where a draft convention is under discussion.

It has been suggested that adult stem cell research would deliver the same benefits as embryonic cell research. Those opposed to embryo research are presenting adult stem cell research as the safe, ethical choice. However much of the scientific opinion presented to the House of Lords Select Committee anticipated that many advances would come from research on ES cells.

The Government's position is that stem cell research is not a matter of one versus the other. The Government wishes to see research using all sources of stem cells. It is far too early to know where the most useful findings will come from.

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