Two research groups in the US have made astounding discoveries using stem cells, including the apparent reversal of Parkinson's disease in a rat. The findings hold great promise for the development of new treatments for intractable diseases.
Stem cells are omnipotent cells which can convert into any tissue type in the body. Most progress so far has been made using embryonic stem cells, but this research is ethically contentious. It involves the use of cells recovered from five-day-old human embryos, which are destroyed in the process.
Details of the two studies were released online yesterday by the journal Nature. One describes stem cells used as replacement brain cells which halted symptoms of Parkinson's disease in an animal.
The other used a new and unexpected source of adult, rather than embryonic, stem cells which may prove to be just as versatile but without the ethical problems.
The stem cell discoveries made so far all point to the great power of these cells both to divide in culture and also to transform or "differentiate" into all the different cell types and tissues of the body.
Researchers using animals have shown again and again the stem cell's ability to replace damaged or missing cells, in a sense becoming "spare part" tissues.
This in effect is what a research group at the US National Institute of Neurological Disorders and Stroke in Bethesda, Maryland, accomplished. Dr Ron McKay and colleagues used cultured embryonic mouse stem cells to treat rats bred to exhibit the effects of Parkinson's disease.
Parkinson's patients gradually lose the ability to produce dopamine, an essential substance in the brain. This leads to the uncontrolled movements associated with the disease.
The Maryland group transformed the mouse stem cells into brain cells, neurons capable of producing dopamine. When transplanted into the rats, the neurons functioned normally, releasing dopamine and allowing them to show signs of recovery in behavioural tests.
The second paper, by a team at the University of Minnesota, may have even more profound effects in the long run. Dr Catherine Verfaillie and colleagues located an adult stem cell which can be recovered without harm to the donor but appears to be just as versatile as embryonic stem cells.
Most international work so far has suggested that adult stem cells are nowhere near as useful as embryonic stem cells. Dr Verfaillie's group cultured adult bone marrow stem cells and from these isolated a separate rare type of "multipotent" adult stem cell which both divides readily in culture but more importantly seems to be able to become any cell type in the body.
These cultured stem cells may become an important source for new treatments, the Minnesota researchers believe. "They may be an ideal cell source for therapy of inherited or degenerative diseases," they wrote in Nature.