Search for body's 'repair kit' is medicine's holy grail

The importance of the latest study into brain repair is the power it gives scientists to pin-point the vital stem cells that are capable of developing into mature nerve cells.

If scientists can harness stem cells in the brain it offers the prospect of regenerating nerve tissues that would otherwise remain damaged for life. It could lead to effective treatments and even cures for chronic debilitating conditions from inherited disorders such as Huntington's chorea to severe brain damage resulting from traffic accidents.

Stem cells, especially those in the brain, are one of the most enigmatic elements of the body. Scientists know they must exist but they do not have an easy way of finding and harnessing them.

Neuroscientists have also come to realise that the brain has an in-built mechanism of regeneration which uses stem cells. They hope to exploit this natural repair kit in future to mend damaged nerves.

For more than 20 years, stem cells have been the Holy Grail of medicine because of their ability to replicate almost indefinitely before they develop into one of the 200 or so specialised tissues of the body, from blood to nerves.

Yet it was only in 1998 that researchers published the first studies showing that it was possible to extract stem cells from human embryos and grow them in the laboratory.

Stem cells derived from early embryos are known to have the greatest ability to develop or "differentiate" into any of the specialised tissues of the body.

The stem cells found in adults have a somewhat similar though muted power of development. Those in the brain for instance are believed to be primarily programmed to turn into brain cells, while those in the bone marrow are designed to develop into blood cells.

If stem cells can be isolated and grown in the laboratory it offers hope of stimulating them with growth factors so they become the mature cells needed for transplant surgery, whether for treating a damaged heart or a defective brain.

However, one of the potential difficulties in using stem cells for transplant medicine is the possibility of tissue rejection. One way around this would be to clone an embryo from a skin cell and use the embryonic stem cells from this cloned embryo.

Work in this area is severely curtailed in many countries, including the US, which has banned the use of government funds for such research. This is one of the reasons why there is such interest in adult stem cells.

- INDEPENDENT