Carbon nanotubes act like 'tiny syringes' during gene therapy

In their latest work, the researchers were able to prevent motor-function loss in rats induced with stroke by using the novel delivery method.

The therapy itself is based on short interfering ribonucleic acids (siRNA), which are string-like segments of DNA material that can interfere with the genetic code.

In the lab, siRNAs are highly effective at switching off ‘rogue genes’ in diseases such as cancer, but are very difficult to deliver to living cells in actual patients. Methods based on virus and liposome (tiny fat vesicles) delivery have shown limited success.

An international team led by Kostas Kostarelos from London University’s School of Pharmacy has found that, under certain conditions, siRNA segments wrap around the length of a carbon nanotube.

‘It’s like you have a kebab skewer and you pierce the cell that takes in the “meat” — there seems to be an electrostatic attraction force between the two,’ Kostarelos told The Engineer.

Once inside the cell, the siRNA switches off a gene responsible for the cascade of neuronal cell death that sets in after a stroke.

Rats that received an injection of the carbon nanotube-siRNA complex performed better in food-retrieval tests than controls after a stroke was induced.

However, Kostarelos admits that one potential problem with the new delivery method is where the nanotubes actually go once they have delivered their payload.

‘It is possible that the cell simply breaks them down, but further work will be needed to assess whether there are any toxicology issues,’ he said.