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Wednesday, 8 May, 2002, 23:19 GMT 00:19 UK
'Scrunched' DNA aids gene patients
laboratory
In the laboratory, the technique proved effective
Scientists have invented a method of compressing DNA which could make gene therapy more effective.

The advance, which is now being tried out on cystic fibrosis patients, may allow the modified genes to slip right into the cell nucleus.

A single strand of DNA contains a complete blueprint for building an entire human.

This means that the DNA molecule is long and unwieldy.

Doctors are looking for ways to smuggle or slip their modified DNA strands into the cells they want to change.

Other methods involve using viruses - which "infect" the cell and pass on the new genes that way, or encasing the DNA in fatty globules called liposomes, which are pulled into the cell by a natural process.

However, infecting patients with viruses carries its own risks, and liposome production is less efficient.

The new technique involves taking the long strands of DNA and "scrunching" them up into a more compact package.

More effective

This tiny ball, 25 nanometres across - 25 millionths of a millimetre - is much smaller than a liposome, and should be able to pass into the nucleus of a cell through pores in its surface, say the scientists.

In cells in a test tube, the tiny DNA packets appeared to be as much as 6,000 times more effective at getting their genes working in the nuclei of cells than DNA-carrying liposomes.

Now basic safety trials have commenced involving human patients, suffering from cystic fibrosis.

This disorder, which involves faulty production of the mucus which lines the lungs, is caused by a single faulty gene.

Cystic fibrosis

Scientists are hopeful that cystic fibrosis could perhaps even be halted if the right kind of gene therapy could be delivered to lung cells.

Trials of the new method have started on 12 people with the condition.

At first, it will be tested on nasal cells before trying to deliver genes to the lungs.

In mice with cystic fibrosis, the replacement gene was expressed in nasal cells, and partially restored proper function.

Dr John Smart, head of the School of Pharmacy at the University of Portsmouth, told BBC News Online: "DNA is a very big molecule, and there are a number of people trying to find ways of getting it into cells.

"However, things that happen in cell culture may not be reproduced in humans or animals.

"But if this DNA can unravel itself after being compressed, then it is promising."

The research was detailed in New Scientist magazine.

See also:

11 Nov 01 | Health
Fat capsules boost breast drug
27 Apr 00 | Sci/Tech
Gene therapy frees 'bubble babies'
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