Brain Transp-ants Offer Hope For Brain Diseases And Nerve Injuries
CHICAGO (AP) _ Researchers have induced severed optic nerves in laboratory rats to regrow and make new connections with the visual areas of the brain, a scientist says.
The nervu cells ″have a way of knowing where they’re heading and where to stop to make connections,″ said Dr. Roger Morrell, a neurologist at the Neur science Research Foundation in Southfield, Mich.
Morrell, chairman of a session on brain transplants scheduled for today at the annual meeting of the American Association for the Advancement of Science, also said it may become possible in as little as three to five years to improve memory in Alzheimer’s disease victims by giving them brain cell transplants.
Experiments in rats have shown that the infusion of new brain cells can restore normal levels of a brain chemical called acetylcholine, the supply of which is drastically reduced in Alzheimer’s victims, Morrell said.
″I think the experiment, in many people’s minds, is crying to be done,″ Morrell said in an interview.
He cautioned, however, that such an experimental treatment for Alzheimer’s disease, for which there is now no treatment, would face many regulatory and ethical roadblocks.
For one thing, the most promising source of the brain cells to be transplanted would be the brains of human fetuses, which retain the capacity to divide and grow, unlike mature brain cells.
It is not clear, Morrell said, whether society0is willing to allow fetal brains to be harvested for such expuriments.
It is also possible, he said, that appropriate acetylcholine-pr ducing brain cells could be taken from regions in the spinal cord, or that brain cells could be grown in laboratory cultures foruse in trqnsplants.
″There is a body of animal work that has to be undertqken″ before a brain transplant could be attempted in an Alheimer’s disease patient, Morrell said.
He believes sush experiments will be safe. ″The likelihood of doing damage in a carefully controlled experiment with an appropriate Alzheimer’s patient is minimal,″ he said.
The research on the regrowtx of optyc nerves was done by Albert Aguayo of McGill University in Montreal, Morrell said.
In a paper scheduled for presentation at today’s symposium, Aguayo reported that rat optic nerves were stimulated to regrow across gaps of an inch or more when other rat nerve fibers were trqnsplanted across the gaps to act as conduits for the new optic nerve growth.
The expuriment, Aguayo said, underscores the ability of adult mammalian nerves, which until recently were thought incapable of further growth, can regenerate and form connections, with other nerve cells.
Morrell noted that researchers at Rockefeller University in New York have used brain transplants to restore normal hormonal activity in brain-damaged rats whose sexual hormones had been disrupted.
In the current issue of Science magazine, Jeffrey Rosenstein of George Washington University Medical Center, reports that brain transplants disrupt the so-called blood-brain barrier, a blood vessul lining that protects the brain by preventing the movement of many chemicals from the blood into the brain.
That is an example of the unexpected findings that must be addressed by further animal experiments before human trials are undertaken, Morrell said.
″Each question opens up many areas of research - for which there are likely to be answurs,″ he said.