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A TRICK borrowed from creatures that can survive dehydration could end the
constant shortage of blood platelets for transfusion. The technique allows dried
platelets to be revived after months or years.

This means they could be stockpiled in blood banks, transported to remote
locations or even taken on spacecraft for astronauts. People could also set
aside some of their own platelets to keep in case they ever run short, which
would eliminate the risk of transmitting diseases such as vCJD.

Platelets are living fragments of cells that are vital to help blood clot.
People who have lost a lot of blood usually need a transfusion of platelets, as
do patients undergoing surgery, chemotherapy or bone marrow transplants.

But platelets can only be stored for 5 days. After that they must be thrown
away. 鈥淏lood centres have to constantly keep producing platelets,鈥� says Mike
Murphy, a haematologist at Oxford University. 鈥淚t鈥檚 a huge logistical
辫谤辞产濒别尘.鈥�

Many researchers are looking for ways to preserve the cell fragments. John
Crowe鈥檚 team at the University of California, Davis, is using trehalose, a sugar
found in many organisms that can survive dehydration. The sugar forms a
glass-like shield around molecules as cells dry out.

Getting hefty trehalose molecules into cells has proved so difficult,
however, other researchers have resorted to genetically modifying the cells that
give rise to platelets so that they make the sugar. But next week, Crowe will
tell a cryobiology conference in Edinburgh that simply warming the cells can do
the trick. At between 30 and 40 掳C, a natural process called endocytosis
kicks in, in which cells engulf surrounding molecules.

鈥淚t was mostly luck,鈥� admits Crowe鈥檚 colleague Fern Tablin. 鈥淲e are now
trying to find out why it works.鈥�

After incubating the platelets in trehalose for several hours, the team
freeze-dries them. The platelets can then be stored at room temperature until
needed. When rehydrated, 85 per cent of the platelets proved healthy. 鈥淭his is
actually better than most blood banks provide after only 5 days鈥� storage,鈥� says
Crowe.

So far the dried platelets have been kept for up to 7 months. The researchers
are testing revived platelets on mice, and hope to start clinical trials within
a year. The high survival rate is promising, says Murphy. But the technique
might be too costly for routine use, he warns.