Researchers have found how a type of nanoparticle being developed for medicine can cause lung damage, and they are zeroing in on a way to counteract the process.

The field of nanotechnology aims to use particles one-billionth of a metre in size to improve the effectiveness of drugs and gene therapy by carrying them to the right place in the body.

Nanoparticles are also used in products such as cosmetics, sporting goods and electronics, but lung damage is a concern.

In this week's Journal of Molecular Cell Biology, Chinese researchers said a class of nanoparticles widely developed in medicine — polyamidoamine dendrimers or PAMAMs — cause lung damage by triggering a type of programmed cell death.

In experiments on human lung cells, they found no evidence that PAMAMs killed cells by apoptosis, the most common type of cell death.

Another type of cell death known as autophagy plays a normal part in cell growth and renewal, but scientists have found that excessive activity of the destructive process can also kill cells.

By injecting mice with an inhibitor of autophagy and then later exposing the rodents to nanoparticles, the researchers found the inhibitor "significantly ameliorated the lung damage and improved survival rates."
