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What are Stem Cells?
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UK Stem Cell Initiative [UKSCI]
What are stem cells?

Stem cells are the very early cells that can develop into almost all other types of cell and tissue. They occur in the early (five-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 umbilical cord blood at birth. They can also be found in some adult tissue, e.g. bone marrow, but they can be 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 cell-based therapies. They are already used for some treatments of cancers (bone marrow stem cells) and in early clinical trials in Parkinson's disease (foetal stem cells). The hope is that tissues derived from stem cells will provide a limitless supply of material to treat currently-incurable diseases and injuries.

The Government wishes to see research using all sources of stem cells. Currently, it is too early to know where the most useful findings will come from.

Most ES cell research uses cells derived from in vitro fertilisation (IVF) embryos donated by couples for research when they are not needed for infertility treatment. Another possible source of ES cells may be from embryos created for research either using egg and sperm or using techniques such as cell nuclear replacement (CNR), or therapeutic cloning. The use of cloning techniques may prove to be a very powerful tool in developing treatments that avoid rejection by the immune system of the patient.

UK law on embryo research has evolved over 20 years through public and parliamentary debate. The Human Fertilisation and Embryology Authority, established in 1991, subjects all embryo research in both the private and public sector to a robust system of case by case review before any license to permit research is issued. Our legislation contains other important protections for the embryo. Research is only allowed for the limited purposes set out in the legislation and no research is allowed on embryos over 14 days old.

copyright: © | last updated 5 May 2005
The UK Stem Cell Initiative is supported by the Department of Health and the Department of Trade & Industry