A to Z of MS Stem cells

Stem cells have the potential to develop into different types of specialised cell and it is this which is driving the scientific interest in their use as a possible therapy in MS.

What are stem cells?

Stem cells are different from all other kinds of cells in the body as they are unspecialised - this means they are not already dedicated to having a specific function in the body. They are able to survive and divide for long periods of time and, under specific conditions, they have the potential to develop into cells with special functions such as the nerve cells in the brain or the muscle cells of the heart.

How might stem cells treat MS?

Stem cells will probably never be used to grow whole organs, but they may be able to repair patches of damage, and this is the reason for researching their use in MS. Three possible ways have been suggested. Stem cells might be persuaded to:

• Develop into nerve cells to repair damage to the brain
• Develop into oligodendrocytes to repair damage to myelin
• Boost the immune system to prevent damage

This could be achieved by encouraging stem cells already resident in the body to develop into, for example, oligodendrocytes. Alternatively, cells could be transplanted that would go on to differentiate into a therapeutic cell type.

Stem cells are found in large numbers in embryos and also in umbilical cord blood. Embryonic stem cells have the potential to develop into any type of cell in the body, and can be isolated and grown in the laboratory. However, the promise offered by embryonic stem cells is balanced by the ethical questions over the use of human embryos, the risk of unwanted cell development into tumours, and the possibility of rejection of the transplant.

Stem cells are found in smaller numbers in adults and may be more limited in their potential to develop into different cell types. They have the advantage that they could be isolated from a person with MS then returned to that person after they had been induced to differentiate into cells that could repair or slow down the effects of MS. Returning cells back to the person who donated them is known as an autologous transplant. It has the advantage that it will not be rejected by the immune system.

Despite some small clinical trials, the interest of the media, and the unrealistic claims by some companies, it is likely to be many years, perhaps ten to twenty years, before stem cell treatments become routinely available for the treatment of MS. More research must be undertaken to ensure that stem cells can be controlled and only develop into the type of cell that is required. It will be important to show that cells can survive, integrate, function and not cause harm to the recipient. In addition, work is needed to allow stem cells to be grown in large numbers before transplantation into a person with MS.

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