Page last updated at 10:16 GMT, Thursday, 11 June 2009 11:16 UK

Nanoparticle lung threat blocked

Gold nanoparticles
Nanoparticles promise to revolutionise medicine

Scientists have identified how a type of tiny nanoparticle can cause lung cancer - and blocked the process.

The fledgling science of nanotechnology promises huge advances in science and medicine, but there are concerns about its safety.

In particular, the microscopic particles it employs have been shown to have toxic effects on the lungs.

The research, by the Chinese Academy of Medical Sciences, appears in the Journal of Molecular Cell Biology.

However, experts said it was not possible to draw general conclusions about all nanoparticles from a study focusing on one specific type.

Nanotechnology involves the modification of atoms and molecules to create new materials which may have unusual physical, chemical, and biological properties.

This provides us with a promising lead for developing strategies to prevent lung damage caused by nanoparticles
Chengyu Jiang
Chinese Academy of Medical Sciences

In medicine alone it is hoped it could be used to develop more effective and better targeted drugs, and new ways to detect and treat disease.

The market is potentially huge, but safety concerns threaten to hold progress back.

Research has shown that most nanoparticles migrate to the lungs, but there is also concern about potential damage to other organs.

The latest research focused on a class of nanoparticles being widely developed in medicine - polyamidoamine dendrimers (PAMAMs).

In tests on cells in the lab, the researchers found the particles cause lung damage by triggering a type of programmed cell death known as autophagic cell death.

Autophagy plays a normal part in cell growth and renewal, but over-activity can lead to unwanted cell death.

However, the researchers also found autophagy could be blocked by using a drug inhibitor.

The findings were confirmed in tests on mice. Animals exposed to PAMAMs showed higher levels of lung inflammation, and higher death rates.

But those that were first injected with the inhibitor were less badly affected.

New strategies

Lead researcher Dr Chengyu Jiang said: "This provides us with a promising lead for developing strategies to prevent lung damage caused by nanoparticles.

"Nanomedicine holds extraordinary promise, particularly for diseases such as cancer and viral infections.

"But safety concerns have recently attracted great attention and with the technology evolving rapidly, we need to start finding ways now to protect workers and consumers from any toxic effects that might come with it."

"The idea is that, to increase the safety of nanomedicine, compounds could be developed that could either be incorporated into the nano product to protect against lung damage, or patients could be given pills to counteract the effects."

Dr Laura Bell, of the charity Cancer Research UK, said: "It's great to see new advances being made to ensure the safety of nanomedicine but this research is still at an early stage and has yet to be tested in people.

"Nanotechnology is an expanding area of research with exciting potential and establishing its safety is essential if we are to realise its potential to treat people with cancer."

It is not clear at this stage whether other types of nanoparticles cause lung damage via the same route.

Professor Ken Donaldson, an expert in respiratory toxicology at the University of Edinburgh, said PAMAMs were highly specialised, and it would be wrong to draw any general conclusions about nanoparticles in general from the study.

Professor Donaldson said PAMAMs were made by the drug industry in tiny amounts, while other nanoparticles were made in much bigger quantities, and potentially posed much more of a risk of accidental exposure.

He said: "The problem is that all nanoparticles are lumped together as if they are one thing and they most certainly are not."



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