快猫短视频

A PINCH of sugar could make human tissues as convenient to store as baker鈥檚
yeast or drugs. Two new tricks for adding a protective sugar to cells enable
them to resist freezing and drying. Cells stored in this way could one day be
used to treat conditions such as Parkinson鈥檚 disease.

Preserving most human cells by freezing or drying them is problematic,
because the ice crystals that form during freezing damage cells, and desiccation
flattens them. But some organisms such as yeast survive both insults by
producing the sugar trehalose which coats important cell components and also
stops ice crystals forming.

Previously, researchers had stopped ice damage in pancreatic cells with trehalose
(快猫短视频, 2 May 1998, p 24),
but other cell types have resisted attempts to introduce the sugar.
Now two groups report new ways around the problem.

Fred Levine and his colleagues at the University of California in San Diego
engineered human fibroblasts to produce two enzymes that make trehalose from its
universal precursors. When they dried the cells and rehydrated them after three
days, about half the cells survived. 鈥淭he goal is to have them go indefinitely,鈥�
Levine says.

At Harvard Medical School in Boston, Mehmet Toner and his colleagues
introduced trehalose into skin cells with the bacterial protein haemolysin,
which forms a pore in the cell membrane. Haemolysin can kill cells, but Toner
used a modified version that shuts down once the sugar had got into the cell.
About 70 per cent of the sugared cells survived freezing for days.

Several diseases can be treated with cultured cells. Experimental treatments
for Parkinson鈥檚 disease, for example, involve transplanting cells that make the
neurotransmitter dopamine into the brain. 鈥淐ells are becoming drugs, so to
speak,鈥� says Toner. 鈥淚f we can dry them we can store them on the shelf like
other drugs.鈥�