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. 快猫短视频s 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鈥檚 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 Fris茅n 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. 鈥淚t鈥檚 hardly ever expressed in the adult system,鈥� says
贵谤颈蝉茅苍.
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To test their hunch, the researchers took a number of ependymal cells from
rats鈥� 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. Fris茅n
says it could mean that not all ependymal cells are stem cells. Or perhaps they
are all stem cells but only at certain times. Fris茅n adds that other stem
cells might also exist: 鈥淚 wouldn鈥檛 be surprised if there were other
辫辞辫耻濒补迟颈辞苍蝉.鈥�
快猫短视频s hope that someday it might be possible to use a patient鈥檚 own stem
cells to repair damage caused by diseases such as Parkinson鈥檚, Alzheimer鈥檚 or
strokes. 鈥淲e are interested in moving in that direction,鈥� says 贵谤颈蝉茅苍.
The new finding improves the prospects of being able to activate stem cells
within the patient鈥檚 own brain, rather than transplanting them, says Samuel
Weiss, a neuroscientist at the University of Calgary. 鈥淚鈥檝e always believed that
if you can identify their precise location, you can develop pharmaceuticals to
specifically target those cells,鈥� he says.