Forget the Mashed Potatoes - Instant Stem Cells; Just Add Water

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Instant stem cells - just add water

Dried cells could aid remote medicine.

19 December 2003

HELEN PEARSON

Cell membranes crack if they are overly parched.

© SPL

Researchers are honing a technique to create dried stem cells that

can be revived just by adding water. The 'instant' cells might make

mobile therapies for remote regions or the battlefield.

Because some stem cells can make fresh bone, muscle or blood, doctors

hope to use them to repair tissues. But, like transplant organs kept

on ice, their shelf life will be limited without an easy way to store

and transport them.

Today researchers save stem cells by freezing them in expensive vats

of liquid nitrogen at -140 ºC. To stop damaging ice crystals forming

inside the cells, they bathe them in a toxic chemical such as

dimethylsulphoxide. This must be washed off before cells can be used.

Air drying

Several scientists are looking for a way to air-dry cells, comparable

to the technique that turns grapes to raisins. Dried stem cells might

be stored in portable packets that can be ripped open and their

contents mixed with water at the scene of an accident, says Ann

Oliver of the Center for Biostabilization at the University of

California, .

Oliver dreams of plastering desiccated stem cells onto a bone-shaped

matrix and then adding water and growth proteins to trigger the cells

to divide and form new bone, ready for a transplant. " It's a pie-in-

the-sky goal, " she admits.

In their latest advance, Oliver and her colleagues dried out

mesenchymal stem cells, sucked from bone marrow. After drying, less

than 40% of the cells was water. When rehydrated immediately

afterwards, up to half grew and divided, Oliver revealed at this

week's American Society for Cell Biology meeting in San Francisco.

Her team soaked the stem cells in an anti-freeze sugar called

trehalose. This sugar sloshes around in organisms that survive

dehydration, such as brine shrimp, baker's yeast and certain drought-

resistant resurrection plants. Adding a second protective compound

called arbutin boosted cell survival further.

Researchers have used trehalose before to preserve other cells. The

real breakthrough, says Fred Levine of the University of California,

San Diego, will come when cells can be revived after several weeks on

the shelf. Levine says his group are achieving similar results as

Oliver's, also with mesenchymal stem cells.

What's more, 80-90% of rehydrated cells must be revived before the

technique can be put into practice, says Mark Pittenger of Osiris

Therapeutics in Baltimore, land, whose company works with

Oliver. " It's unclear when it'll come along, " he says.

Wet ones

Dehydration must remove as much water as possible so that cells'

metabolism is halted, otherwise they churn out waste that poisons

their surroundings. But cell membranes crack if they are overly

parched. Researchers are experimenting to strike the right balance.

Stem cells have nuclei that must be perfectly preserved

Oliver and her team used a similar technique to dry and store blood

platelets for transfusions for up to two years, without causing them

any obvious harm. Transferring the technique to stem cells is tricky

because, unlike platelets, they have nuclei that must be perfectly

preserved.

© Nature News Service / Macmillan Magazines Ltd 2003