New Findings In Stem Cell Research

New developments in stem cell research might someday offer a way out of the current ethical debate over the use of stem cells at one time believed to be available only from fetal tissue.

CBS News Correspondent Dan Raviv reports a new study says stem cells taken from dead bodies have reproduced in a laboratory and grown into different types of nerve cells.

A second study reports success in growing brain cells from bone marrow cells which normally would have become bone, cartilage, muscle, tendon and fat cells.

A third looks at efforts to grow nerve cells from rat skin and human scalp cells.

Stem cells are valued because they can turn into different types of brain and nerve cells, a phenomenon that has many scientists hoping they might someday be able to grow cells to replace diseased cells.

The new developments were reported this past weekend in New Orleans, at the annual meeting of the Society for Neuroscience.

The research findings, says Ronald D.G. McKay of the National Institute of Neurological Disorders and Stroke, are not yet clinical solutions.

He notes that there are big differences among stem cells from embryos, from fetuses and from adult tissue, and scientists don't really know much yet about any of them.

"We can't look in a dish at a mixed population (of cells) and say 'That is a stem cell,'" explains Fred Gage of the Salk Institute at LaJolla, Calif., where the cadaver work was done. "Different people have different ideas."

The main definitions, said Ira Black of the University of Medicine and Dentistry of New Jersey, are that stem cells are immature cells which can duplicate themselves and grow into different kinds of mature cells.

Gage's research used bits of tissue taken soon after death from children and young adults who had died of various neurological diseases.

His lab got the tissue 10 hours to three days after death. In every case - as well as with cells from a man who died at 72 - researcher Theo Palmer was able to get some of the cells to divide and reproduce themselves, and to grow into different kinds of nervous system cells, Gage said.

Black's research has instead focused on bone marrow cells. In a previous study, he and his colleagues were able to turn 80 percent of the bone marrow cells taken from rats and humans into nerve cells. In his new study, that success rate rose to better than 99 percent.

Black is intrigued by Gage's findings and says they "offer the opportunity to do experiments that would otherwise be virtually impossible, unless one used material obtained at neurosurgery."

In an interview with CBS News Radio, Black also points out that this would open the way to exploration of the possibilities of using "adult neural stem cells, in a manner that obviously would be extremely difficult if we had to use tissue from living patients."

Another scientist, Freda Miller of McGill University, has been doing research aimed at turing rat skin and human scalp cells to nerve cells.

"That's yet another extraordinary finding," said Black.

"It may be that there is a variety of easily accessible sources that can generate neurons," he said. If that's the case, he said, scientists will need to find out what they all have in common.

McKay described turning mouse embryo stem cells into brain cells which make dopamine - the chemical neurotransmitter whose absence causes Parkinson's disease.

Researchers have transplanted dopamine-producing cells derived from fetal tissue into peoples' brains. But there is enough for only a few of the estimated 1.2 million sufferers, and research has been slowed by restrictions on the use of federal money for studies involving fetal tissue.

"If you're going to use this as a routine therapy, you need access to large numbers of cells," McKay said.

McKay said his laboratory has produced unlimited numbers of dopamine neurons - but they produce high levels of dopamine only for a short time.

"We need to know what kind of signals to give them" to get the best production, he said.

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