X-Message-Number: 13191
From: Brent Thomas <>
Subject: new cell dessication methods
Date: Thu, 3 Feb 2000 14:40:19 -0500 


Candied Cells Have Longer Shelf Life

      You can buy them in any toy store: dried sea monkeys
      that spring to life in a dish of water. Now researchers
      have borrowed a chemical trick from these tiny animals
      to revive dried or frozen human cells. The technique
      could lead to off-the-shelf human cells and tissue for
      blood transfusions, skin grafts, and a variety of other
      medical treatments, two teams report in the 31 January
      Nature Biotechnology. 
            Organisms as diverse as sea monkeys (they are tiny
      shrimp, in fact), yeast, and microbes called tardigrades
      can survive decades without water. But cultured human
      cells quickly die unless they are coddled. To help human
      cells survive cold storage, explains biomedical engineer
      Mehmet Toner of Harvard Medical School in Boston,
      researchers coat them with protectants, freeze them
      slowly so damaging ice crystals don't form, and store
      them in expensive tanks cooled by liquid nitrogen. 
            To find a better way to keep
      cells on ice, Toner's team loaded
      cells with trehalose, a sugar that
      protects cells in some organisms
      from ice crystals and desiccation.
      Trehalose can take the place of
      water in the cell, forming a
      protective coat around enzymes,
      membranes, and DNA. Our bodies don't make
      trehalose, and it is too big to cross the cell membrane, so
      they snuck it into cells via alpha-hemolysin, a bacterial
      toxin that pokes holes in the membrane large enough to
      let the sugar in. Without trehalose, less than 1% of cells
      survived freezing; when laced with the sugar, 72% of the
      cells revived after thawing. 
            Trehalose also preserves human cells that are dried,
      reports a second team led by geneticist Fred Levine of
      the University of California, San Diego. The researchers
      engineered cells called fibroblasts to produce the
      bacterial enzymes that make trehalose. Normal cells die
      within 1 day after being dried out, but the altered cells
      were fine for up to 5 days without water. 
            It's "remarkable" that simply adding a sugar is
      enough to preserve both frozen and dried cells, says
      biochemist John Crowe of the University of California,
      Davis. The method might make it possible to store dried
      human tissue on a shelf indefinitely. "It's been a dream of
      a lot of people to do that for a long time," says Crowe. 
            --Dan Ferber 

Brent Thomas

Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=13191