WEDNESDAY, August 16 (HealthSCOUT) -- An international team of researchers has produced the first human nerve cells grown from embryonic stem cells.

The researchers hope that once their technique is refined to produce pure populations of certain types of nerve cells, the cells could be used to test new medicines. Or, specific types of cells could be transplanted into patients with neurodegenerative illnesses like Parkinson's disease or spinal cord injuries.

Stem cells are primitive cells that can develop into virtually any type of cell. In the past few years, researchers have coaxed stem cells to become muscle, blood-producing and insulin-producing cells, to name a few.

For six years, scientists from Australia, Israel and Singapore have been figuring out how to coax embryonic stem cells into nerve cells. They started by isolating stem cells that were precursors to nerve cells, and controlling their development using chemical growth factors and growth mediums until they turned into mature nerve cells. Their study appears in this month's Nature Biotechnology.

"There are so many possibilities that evolve from here," says Alan Trounson, of Monash University in Melbourne, Australia.

If researchers can learn which genes and what external factors control how cells differentiate [turn into specialized cells], he says, the knowledge could be used to regenerate tissues.

These cultured cells could also be used to screen medications to determine how drugs work. The cells also could replace animal testing for drugs or other products.

"Eventually, they'll also be used for transplantation," says Trounson. "The potential applications that are worth looking at, at this point, are Parkinson's disease, stroke, Alzheimer's disease, and maybe even recovery of motor neuron defects from spinal cord damage."

These cells could also be used to deliver gene therapies, adds Trounson, replacing the viruses that are currently used. This could apply to treating cystic fibrosis, for instance, or as part of a new approach to immunization.

Janet Rossant, a professor of molecular and medical genetics at the University of Toronto in Canada, says these cells could have multiple uses.

"This could really lead to novel therapies for degenerative diseases in humans," Rossant says. "It's also true that these cells will give you more insight into how human embryo cells develop."

The researchers still need to determine whether these cells from one stem cell line can be used in any person, or whether they might be rejected. Trounson says he's less worried about rejection if they're used in the brain, because the blood-brain barrier should protect them against rejection.

"I think the next five to 10 years of research will tell us whether this will be the era of an absolutely new medicine or another great potential that's never realized," says Trounson.