Mouse tests show stem cells treat brain disease

WASHINGTON, Mar 12 (Reuters) Human stem cells taken from both embryos and fetuses delayed a fatal brain and nerve disease in mice, moving throughout the brain to take on the jobs of damaged neurons, scientists have reported.

They said their study, published in the journal Nature Medicine yesterday, could lead to ways to treat a range of neurodegenerative diseases such as Parkinson's, Alzheimer's and amyotrophic lateral sclerosis, also known as ALS or Lou Gehrig's disease.

For their study, Dr Evan Snyder of the Burnham Institute for Medical Research in La Jolla, California and colleagues used mice bred with the equivalent of Sandhoff disease.

''Children with the disease have severe mental retardation and motor dysfunction, and death typically occurs in infancy,'' the researchers, who included a team at Oxford University in Britain, Yonsei University in Seoul, Korea and elsewhere, wrote in their report.

It is marked by inflammation that kills brain cells, and it is impossible to treat in part because of the blood-brain barrier, a molecular gateway that keeps many drugs out of the brain.

''The Sandhoff disease mouse typically becomes symptomatic by 90 days of age and dies between 114 and 130 days, depending on strain and/or cage conditions,'' the researchers wrote. Human children with Sandhoff rarely live past age 6.

Snyder's team made up a mixture of human embryonic stem cells, taken from days-old human embryos left over at fertility clinics, and human fetal stem cells.

They transplanted these into the brains of the mice and noted no problems. No tumors formed, the mice did not ''reject'' the foreign cells, and the treatment seemed to reduce inflammation.

The transplanted human cells replaced damaged nerve cells and carried nerve signals. They also boosted the brain's supply of the enzyme Hex, which is lacking in Sandhoff disease.

The treated mice lived 70 per cent longer than untreated mice. The disease eventually came back, but the researchers hope to test the theory that they could keep it at bay by giving booster injections of the stem cells to take over the functions of the mutated natural brain cells.

Sandhoff disease belongs to a class of genetic diseases called lysosomal storage diseases. They affect one in 5,000 patients, mostly children.

Sandhoff is caused by a mutation in the gene for an enzyme called hexosaminidase or hex, which brain cells need to get rid of excess fatty material called lipids.

When the lipids build up, brain cells die. It is similar to Tay Sachs disease, and there is no treatment for either Tay-Sachs or Sandhoff.

REUTERS SB BST0934