N E W O R L E A N S, Nov. 6, 2000 -- Scientists have coaxed new life out of deadbrains.
It turns out that even cadavers can supply the incrediblyversatile brain stem cells — master cells which can turn intodifferent kinds of brain and nerve cells — once thought availableonly from fetal tissue.
So can skin. And it appears that just about every bone stem cellcan be tweaked to produce brain cells.
“It’s an extraordinarily exciting field,” said Ronald D.G.McKay of the National Institute of Neurological Disorders andStroke.
Ethical Dilemma of Fetal Tissue
Several reports to the Society for Neuroscience seem to offeryet more possible solutions to the ethical dilemma blocking stemcell studies which use human fetal tissue.
But they are not yet solutions and may never be, said McKay andtwo other scientists who discussed their findings at a newsconference Sunday at the society’s annual meeting.
There are big differences among stem cells from embryos, fromfetuses and from adult tissue, and scientists don’t really knowmuch yet about any of them, they said.
“We can’t look in a dish at a mixed population [of cells] andsay ‘That is a stem cell,’” said Fred H. Gage of the SalkInstitute at LaJolla, Calif., where the cadaver work was done.“Different people have different ideas.”
The main definitions, said Ira Black of the University ofMedicine and Dentistry of New Jersey, are that stem cells areimmature cells which can duplicate themselves and grow intodifferent kinds of mature cells.
Gage’s research used bits of tissue taken soon after death fromchildren and young adults who had died of various neurologicaldiseases.
Cells Are Good for Days
His lab got the tissue 10 hours to three days after death. Inevery 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 divideand reproduce themselves, and to grow into different kinds ofnervous system cells, Gage said.
Black grew brain cells from cells taken from bone marrow, wherethey ordinarily would have created bone, cartilage, muscle, tendonand fat cells.
He previously reported that he and his colleagues had been ableto turn 80 percent of the bone marrow cells taken from rats andhumans into nerve cells. Additional work has brought that up tomore than 99 percent, he said.
Freda Miller of McGill University had been scheduled to discussher work turning rat skin and human scalp cells to nerve cells butcould not make it.
“That’s yet another extraordinary finding,” Black said.
“It may be that there is a variety of easily accessible sourcesthat 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 cellswhich make dopamine — the chemical neurotransmitter whose absencecauses Parkinson’s disease.
Researchers have transplanted dopamine-producing cells derivedfrom fetal tissue into peoples’ brains. But there is enough foronly a few of the estimated 1.2 million sufferers, and research hasbeen slowed by restrictions on the use of federal money for studiesinvolving fetal tissue.
“If you’re going to use this as a routine therapy, you needaccess to large numbers of cells,” McKay said.
McKay said his laboratory has produced unlimited numbers ofdopamine neurons — but they produce high levels of dopamine onlyfor a short time.
“We need to know what kind of signals to give them” to get thebest production, he said.