Human stem cells help brain-impaired mice

By Will Dunham

WASHINGTON (Reuters) - Injecting human stem cells into the brains of mice helped them recover almost fully from a neurological condition similar to a group of childhood diseases in people, researchers said on Wednesday.

Some, but not all, of the mice in the study made major improvements after a one-time injection of stem cells, leading the scientists to express hope that the same approach might be tried in children within just a couple of years.

The treatment, in essence, fixed defective wiring throughout the brain and spinal cord, the researchers said.

"We were just waiting for them to die day by day, but they just didn't. They got better day by day," said Dr. Steve Goldman of the University of Rochester Medical Center in Rochester, New York, who led the study.

"They started to shake less. They started to regain strength. They started to move around more. They started to explore more. They started to have shorter seizures and then fewer."

The incurable diseases for which this kind of stem-cell injection might work include cerebral palsy, Tay-Sachs, Krabbe's, Canavan's disease and Pelizaeus-Merzbacher disease, according Goldman.

"Potentially it may give us a means of treating, using cell transplants, a number of diseases," Goldman, whose study is in the journal Cell Stem Cell, said in a telephone interview.

Doctors have long struggled to find ways to help children with these conditions.

The 26 mice in the study were bred so their bodies did not make myelin, a fatty coating around nerve cells that serves much as insulation does around an electrical wire. The condition leaves the mice prone to seizures and weak and makes it hard for them to stand or walk.

The treatment involved a one-time injection of a kind of human fetal stem cell known as a glial stem cell into mice shortly after their birth. Stem cells have the ability to develop into various types of cell in the body, and these particular cells turn into the cells involved in making myelin.

About 300,000 of these stem cells were injected into the brain of each mouse in five different locations to better allow them to spread to the entire brain and spinal cord. Myelin coats long sections of neurons and electrical signaling becomes impaired without it.

The mice had a condition that, untreated, normally kills them within about 20 weeks of birth. Twenty of the treated mice lived a bit longer but still died. However, six others made dramatic improvements -- four returning nearly to normal.

By the time they were nine months old, they were just about as good as normal mice aside from a bit of a body tremor when walking forward, Goldman said.

The approach showed that doctors can restore normal myelin production in these conditions, he added.

(Editing by Maggie Fox and Cynthia Osterman)