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From: "Jan Coetzee" <>
Subject: Dried-out human cells can come back to life
Date: Thu, 19 Apr 2001 20:59:30 -0400

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New Scientist issue: 21st April 2001

Contact: Claire Bowles


Dried-out human cells can come back to life

NORMAL human cells have been dried out and revived eight days later using a
trick evolved by a bacterium that can survive for centuries without water.
The technique could have all sorts of medical uses.

Blood for transfusions could be stored for long periods, for example, or
carried to remote disasters without having to be kept cool. Antibodies and
vaccines would have an almost unlimited shelf life, making them easier to
distribute in developing countries.

Desiccated medical supplies could even be sent on long space missions. And
it should become possible to make cell-based biosensors to detect poisons
such as nerve gas. "You could rehydrate them when you needed the sensor,"
says Malcolm Potts of the Virginia Tech Center for Genomics in Blacksburg,
who developed the technique.

Our cells usually die within seconds without water. But Potts and his
colleague David Helm knew of a photosynthetic bacterium, or cyanobacterium,
called Nostoc commune, that can survive such harsh conditions. N. commune
lives on exposed rock surfaces, where it often dries out. When the rock gets
wet again the cells come back to life, swelling up to form gel-like masses
whose sudden appearances led to the popular names "star jelly" and "witches

N. commune survives by surrounding itself with a slimy substance called
glycan, Potts says. "It forms a woolly overcoat for the cells." Glycan is
thought to protect cell membranes, as well as slowing the rate of drying.

So Potts and Helm tried mixing purified glycan with human kidney cells and
drying them out at room temperature. When they rehydrated the cells 8 days
later, half of the cells recovered and started dividing again, Potts told a
meeting of Britain's Society for Experimental Biology in Canterbury earlier
this month. "It's a breakthrough," says Potts. "By applying the techniques
we have found in cyanobacteria, we can dry out human cells. It's very

Alan Tunnacliffe of the Institute of Biotechnology at Cambridge University
says he's surprised the cells survived with only glycan to protect them, as
it does not get inside the cells. "I am a little sceptical," he says. "But
if it does work, it is a major achievement."

Last year, Fred Levine of the University of California in San Diego reported
that he had revived dried human cells after 5 days (New Scientist, 19
February 2000, p 11). But this technique doesn't work for normal
cells-Levine's team had to genetically modify the cells to make a sugar
called trehalose, which protects cells against freezing and drying from the

Other researchers have failed to repeat Levine's results. But he insists the
technique works. "We have been drying cells, putting them in a standard
cardboard container, sending them [from California] to the East Coast and
having them successfully rehydrated," he says. Potts and Helm hope that one
day tissues and perhaps even organs could be dried out and revived. But this
won't be achieved with glycan alone, Potts says. "In the end it's bound to
require a combination of different approaches."

Author: Joanna Marchant

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