Stem cells 'target disease'

Their latest work suggests that stem cells are naturally attracted to diseased areas of the brain - a trait they want to exploit.

" [Stem cells] can be used like heat-seeking missiles "
Dr John Yu

The team has shown for the first time that adult bone marrow stem cells can be differentiated into several cell types in the central nervous system.

Their work has been done so far only in rats and they now want to extend it to human patients.

Stem cells are the "master cells" that give rise to the various specific cells of the body. Scientists envision using these "starter" cells to treat a wide range of conditions, replenishing tissues that have been damaged by disease.

Chemical attraction

Tumour cells that spread throughout the brain are very difficult to treat with surgery and conventional techniques like radiotherapy.

But the latest work from Dr John Yu, from the Comprehensive Brain Tumor Program, at the Cedars-Sinai Maxine Dunitz Neurosurgical Institute in Los Angeles, and colleagues offers a potential solution to this difficulty.

The scientists found that stem cells are naturally drawn to damaged areas of the brain - quite why, they do not know.

Dr Yu said: "Areas of disease in the brain may be making some chemicals that attract these stem cells there.

"If you manipulate the stem cells and make them secrete proteins from genes of interest into these areas of disease, they can be used like heat-seeking missiles."

So stem cells could eventually be developed to deliver chemicals to repair brain damage.

Adult stem cell breakthrough

The scientists' work also adds to the body of evidence that shows adult stem cells are more versatile than previously thought.

The researchers found that adult stem cells from bone marrow can differentiate into several cell types of the central nervous system.

Many scientists maintain that the most versatile types of stem cells come from embryos or foetuses.

These can develop into all the different cell types in the body - but they represent a minefield of ethical dilemmas.

Adult stem cells not only avoid these moral issues, it is possible they will be more effective as well.

Scientists hope to replace the damaged areas of the brains in patients with diseases like Alzheimer's, Parkinson's and multiple sclerosis.

If they use embryonic of foetal cells to do this, there is a danger that patients' bodies may reject the new cells.

But if the stem cells used come from the patients' own adult tissues then there is no danger of them being rejected and the treatment is much more likely to work.

Dr Yu told the BBC he hopes to start clinical trials with stroke patients using their own stem cells in a year's time.

Dr Yu and colleagues have published details of their work in the Journal of Experimental Neurology.