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From newscientist.com
Living forever
19:00 18 January 01
Philip Cohen
The discovery that ordinary rodent cells can replicate forever has challenged the widely held belief that most mammal cells are intrinsically mortal.
The work suggests that a similar approach could allow ordinary human cells to grow into limitless tissues for transplants. Until now, the only human cells thought fecund enough for the purpose of transplant growth were rare, primitive cells called stem cells.
A few cells, including bacterial and cancer cells have previously been shown to replicate forever in the laboratory. But most healthy mammalian cells managed just a few dozen divisions before they stopped, a process known as replicative senescence. This was thought to be a fundamental property programmed into the genetics of each cell.
But two research teams at University College London found that some rat cells stop dividing only because of the mixture of nutrients in which they are grown. Given a more optimal brew, the cells managed as many as hundreds of divisions without signs of ill health.
"The cells have a much greater capacity to grow than anyone imagined," says one of the researchers, Dean Tang, who has since moved to the University of Texas in Smithville. And the cells were able to make the leap to immortality without taking on the undesirable characteristics of cancer cells, such as uncontrollable growth.
Human cells have an additional barrier to unfettered replication - most lack the chromosome repair enzyme called telomerase that rat cells possess. But the work suggests that correcting this single defect and finding appropriate growth broth could allow cells to grow indefinitely.
"There may be no fundamental obstacles to tissue engineering with normal human cells," says cell biologist Woodring Wright at the University of Texas Southwestern Medical Center in Dallas.
[ 07-08-2001: Message edited by: Ice Honkey ] |
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