Stem cell therapy : Department of Health - Gene Therapy Advisory Committee (GTAC)

What are stem cells?

Researchers have been able to grow certain types of stem cells apparently indefinately in the laboratory. Called a stem cell line, these cells have two very important properties. Firstly, they can self-renew or form ‘carbon copies’ of themselves. Secondly, they can be made to differentiate, or convert, into any one of the different types of specialised cell in the human body. Stem cells which can differentiate into any type of cell in the body are referred to as pluripotent. For example, stem cell lines dervied from the early embryo, or embryonic stem cells, are pluripotent.

Some of our fully-developed tissues also posess stem cells, known as adult stem cells. These stem cells are different from embryonic stem cells because they cannot form any type of cell in the body, that is, they are not pluripotent. Adult stem cells can, however, effectively replace a small number of cell types within their tissue of origin.

A very recent breakthrough has shown that normal adult body cells can be ‘reprogrammed’, or switched back, into stem cells that appear to show all the properties of embryonic stem cells. This is done by ‘re-programming’ the nucleus of adult body cells using genetic modification so that the cells revert back to their earliest developmental stage in the embryo.

What is stem cell therapy?

Perhaps the most successful medical exploitation of stem cells to date has been the use of bone marrow transplantation as therapy for a variety of cancers of the blood and immune systems. Researchers are also hoping to exploit other forms of adult stem cell to treat diseased or damaged tissues of patients.

Given their unrestricted potential to form any kind of cell in the body, scientists have more recently begun to research the possibility of using embryonic stem cell lines to generate replacement cells for a range of diseases where there are unmet medical needs. Because the embryonic stem cell lines can be grown in large amounts, it should be possible to generate sufficient quantities of cells to replace damaged or diseased tissue in patients. This type of approach is known as stem cell therapy or regenerative medicine. Induced pluripotent stem (iPS) cell lines may also hold the same promise as embryonic stem cells in contributing to the development of novel medical treatments and cell therapy.

GTAC oversees clinical trials involving cells derived from stem cell lines.A stem cell line is a permanently established culture of unspecialised cells derived from a single parental cell, or group of parental cells, that can (1) proliferate in vitro for a prolonged period when given appropriate nutrition and space and (2) be made to differentiate in culture into more specialised types of cells when given appropriate chemical or molecular cues.

This includes cell therapies derived from:

genetically modified cells
embryonic stem cell lines
multipotent stem cell lines
mesenchymal stem cell lines
foetal stem cell lines
Induced pluripotent stem (iPS) cell lines

4 December 2008: WARNING ON UNPROVEN STEM CELL TREATMENTS

The Department of Health is aware of international, web-based schemes which purport to offer patients "stem cell treatments", "stem cell therapies" or participation in "stem cell trials". These claim to involve treatments for a variety of diseases, including multiple sclerosis, HIV infection, Parkinson's disease and cerebral palsy. The schemes promise to treat UK patients overseas "for free." However, it is clear that there are, in fact, significant hidden costs and risks for potential patients. Some such schemes have already been shut down by the local regulatory agencies, but others remain in operation. For patients who are considering involvement in such "stem cell trials", we strongly recommend that you:

1. Discuss participation in such schemes with your GP or consultant.

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