Cells for suicide

Reports that apoptosis or programmed cell death happens when a brain artery gets blocked or ruptured. Risk of cell mutation after a stroke; Implications of preventing apoptosis; Occurrence of apoptosis in the prenatal brain.

By PT Staff, published on July 01, 1995

It's a noble image: brain cells valiantly fighting for their lives after astroke has cut off their precious blood supply. But some researchers now think that a more macabre process occurs when a brain artery ruptures or becomes blocked--mass suicide.

Scientists call it "programmed cell death," or apoptosis, and it happens all over your body. Cells in the skin, for example, do themselves in as they approach the epidermal surface, where they replace dead cells that have sloughed off.

But unlike skin cells, neurons can't replenish their numbers by dividing. Why kill themselves, then, in the aftermath of a stroke? Because a damaged cell runs the risk of mutating, suggests Matthew Linnik, Ph.D. Such a cell could become cancerous or wreak havoc in other ways.

"If something goes wrong in the brain, it is far better for the organism if the cell commits suicide than for it to potentially mutate," says Linnik, a senior scientist at the Marion Merrell Dow Research Institute.

By inserting a gene that prevents programmed cell death into a tiny section of rat brains, Linnik and Howard Federoff, M.D., Ph.D., of Albert Einstein College of Medicine, reduced neuronal suicide after a stroke. The brain area they protected was barely larger than the period at the end of this sentence, but the implications of preventing apoptosis are tremendous, particularly if the process turns out to play a role in such neurodegenerative conditions as Alzheimer's and Parkinson's disease.

Ironically, programmed cell death also occurs where you might least expect it: in the prenatal brain. The brain of a human fetus has twice as many cells as that of an adult, but half of those cells are weeded out in the womb. If a particular fetal brain cell isn't necessary for developing neural pathways, its suicide genes kick in.

"That genetic program is still there for the rest of your life; it's just inactive," explains Linnik. He speculates that the suicide program somehow gets reactivated when stroke or degenerative diseases occur.