Drugs developed for organ transplants are showing remarkable promise in a totally different area - protecting nerve cells from damage and helping them regrow after injury, studies show.
Derivatives of drugs such as FK506 and cyclosporin, which help keep the body from rejecting transplanted organs, may be useful in treating strokes and spinal cord damage, and Alzheimer's, Parkinson's and related diseases of the nervous system, neuroscientist Solomon Snyder said this week.In test-tube experiments, as well as trials in rats and monkeys, FK506 and cyclosporin, as well as modified versions of the drugs, can help restore damaged nerve cells.
"It's clearly something worth studying," said Snyder, a professor of neuroscience, pharmacology and psychiatry at the Johns Hopkins University School of Medicine.
Animal experiments have shown that the immunosuppressive drug FK506 and other drugs based on it can improve the regeneration of facial and other nerves that have been crushed. In test tubes the drugs also have stimulated regrowth in the kind of nerve cells that are important in Alzheimer's and Parkinson's disease.
But Bruce Gold, a professor at the Oregon Health Sciences University in Portland who has made important discoveries in the area, cautioned that it will be awhile before the drugs are used in humans.
"It's in the early experimental stages," he said.
Now researchers are beginning to test the drug in monkeys that have a disorder similar to Parkinson's. If those tests go well, Snyder said, human tests of the drug could begin in a year or so.
"It's preliminary, but let me tell you, it's working," he said.
Researchers found in the 1960s that they could shut down the body's immune system by interfering with a biochemical pathway that eventually causes an attack on materials alien to the body, such as a newly transplanted kidney or liver. Without the drugs that do that, organ transplants wouldn't be possible.
Neuroscientists recently discovered that key elements of that biochemical pathway also are present in the brain. And in a host of ailments, those same biochemical steps lead to processes that kill nerve cells.
So just as gumming up the immune system's works with FK506 and cyclosporin has proven beneficial, the hope is that similar strategies might work in the brain, spinal cord and other parts of the nervous system.