Is this the mother of all brain cells?

 作者:符屐会     |      日期:2019-03-08 09:03:01
By Alison Motluk CELLS in the brain that neurologists thought were mere structural supports could turn out to be the key to future treatments for degenerative brain diseases. Scientists in Sweden have shown that ependymal cells do more than simply separate the fluid that surrounds the brain and spinal cord from neural tissue. They may, in fact, contain the brain’s reserve of stem cells. Stem cells go on to develop into mature cells, which in the brain include neurons and various types of supporting cells called glia. It was long believed that only embryonic brains had stem cells, which would mean that unlike bones or blood, adult brains could not regenerate. But in the past few years, scientists have shown that adult brains can also sprout new neurons, suggesting that neural stem cells do exist, though no one knew which cells they were. For Jonas Frisén and his colleagues at the Karolinska Institute in Stockholm, ependymal cells were the prime suspects. Earlier studies had shown that a gene called nestin is expressed in these cells following spinal cord injuries, in regions of the brain where cells are regenerating, and in the developing embryo. “It’s hardly ever expressed in the adult system,” says Frisén. To test their hunch, the researchers took a number of ependymal cells from rats’ brains and cultured each one separately. More than 6 per cent of the cultures developed all other major types of brain cell, the hallmark of stem cells (Cell, vol 96, p 25). Why many of the cells did not mature in this way is unclear. Frisén says it could mean that not all ependymal cells are stem cells. Or perhaps they are all stem cells but only at certain times. Frisén adds that other stem cells might also exist: “I wouldn’t be surprised if there were other populations.” Scientists hope that someday it might be possible to use a patient’s own stem cells to repair damage caused by diseases such as Parkinson’s, Alzheimer’s or strokes. “We are interested in moving in that direction,” says Frisén. The new finding improves the prospects of being able to activate stem cells within the patient’s own brain, rather than transplanting them, says Samuel Weiss, a neuroscientist at the University of Calgary. “I’ve always believed that if you can identify their precise location, you can develop pharmaceuticals to specifically target those cells,