X-Message-Number: 16073
Date: Thu, 19 Apr 2001 11:59:45 -0700
From: Jeff Davis <>
Subject: dessication

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 butter".
    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 exciting."
    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 

    New Scientist issue: 21st April 2001 

			Best, Jeff Davis

	   "Everything's hard till you know how to do it."
					Ray Charles	

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