DNA Nanoballs Boost Gene Therapy

Scrunching up DNA into ultra-tiny balls could be the key to making gene therapy safer and more efficient. The technique is now being tested on people with cystic fibrosis.

So far, modified viruses have proved to be the most efficient way of delivering DNA to cells to make up for genetic faults. But viruses cannot be given to the same person time after time because the immune system starts attacking them. Viruses can also cause severe reactions.

As a result, researchers increasingly favour other means of delivering genes, such as encasing DNA in fatty globules called liposomes that can pass through the membranes round cells. But simply getting a gene into a cell is not enough - for the desired protein to be produced, you need to get the gene into the cell's nucleus.

At around 100 nanometres in size, most liposomes are too large to pass through the tiny pores in the nuclear membrane except when the membrane breaks down during cell division. Even if cells are rapidly dividing, delivering genes via liposomes is not very efficient - and it is no good for slowly dividing cells such as those lining the lungs.

But researchers at Case Western Reserve University and Copernicus Therapeutics, both in Cleveland, Ohio, have developed a way to pack DNA into particles 25 nanometres across, small enough to enter the nuclear pores.