Scientists have coaxed new life out of dead brains.
It turns out that even cadavers can supply the incredibly versatile brain stem cells — master cells which can turn into different kinds of brain and nerve cells — once thought available only from fetal tissue.
So can skin. And it appears that just about every bone stem cell can be tweaked to produce brain cells.
“It’s an extraordinarily exciting field,” said Ronald D.G. McKay of the National Institute of Neurological Disorders and Stroke.
Ethical Dilemma of Fetal Tissue
Several reports to the Society for Neuroscience seem to offer yet more possible solutions to the ethical dilemma blocking stem cell studies which use human fetal tissue.
But they are not yet solutions and may never be, said McKay and two other scientists who discussed their findings at a news conference Sunday at the society’s annual meeting.
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, they said.
“We can’t look in a dish at a mixed population [of cells] and say ‘That is a stem cell,’” said Fred H. 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.
Cells Are Good for Days
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 grew brain cells from cells taken from bone marrow, where they ordinarily would have created bone, cartilage, muscle, tendon and fat cells.
He previously reported that he and his colleagues had been able to turn 80 percent of the bone marrow cells taken from rats and humans into nerve cells. Additional work has brought that up to more than 99 percent, he said.
Freda Miller of McGill University had been scheduled to discuss her work turning rat skin and human scalp cells to nerve cells but could not make it.
“That’s yet another extraordinary finding,” Black said.
“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.