Nanoparticle safety looking more complicated - November 05, 2009
A paper has been published today in Nature Nanotechnology with a fairly provocative title: Nanoparticles can cause DNA damage across a cellular barrier.
But before we start shouting “grey goo” from the rooftops and blaming nanotechnology for ruining our lives, the paper requires some more considered thought. We already suspect that certain nanoparticles cause damage, but the need for more research is abundantly clear.
What the team, led by Charles Case from the Bristol Implant Research Centre, UK, and his colleagues have shown is that in their lab situation – more of which later – certain nanoparticles can reach through a cellular barrier and cause damage to the DNA in fibroblasts, which are cells important in wound healing.
The fact that nanoparticles can cross a cellular barrier (think blood-brain barrier, or the placenta) could cause alarm, but in this case shouldn’t.
The report is likely to be more interesting for those wanting to study the cellular processes that are happening. The set up in the lab was far removed from a real-life situation. Case’s team used a type of cell that can be used to build a structure that mimics a cellular barrier, they then built up three layers of these cells to make sure there were no gaps, and put the fibroblasts behind it. They then exposed the system to a very high dose of cobalt/chromium nanoparticles – because these are created in small amounts when artificial joints wear during use.
The results showed that the nanoparticles stayed in amongst the barrier cells without killing them. They nanoparticles didn’t reach the fibroblasts. So how was the DNA in the fibroblasts damaged? This is the part that is likely to whet the appetites of other scientists in the field. It looks like the nanoparticles set off a series of signals within the cells of the barrier, that ultimately led to the release of DNA-damaging ATP through two specific channels at the edge of the barrier.
This signalling process meant that the fibroblasts’ DNA was more damaged when the barrier was present than when the fibroblasts were directly exposed to the nanoparticles.
So what does this mean? I can’t put it any better than Andrew Maynard, nanotech regulation expert from the Woodrow Wilson International Center for Scholars in Washington, DC, who told me, “it's an important study as it raises possible new ways in which harm could occur following exposure. But while it raises new questions, it is far from conclusive on whether this is a relevant or significant way in which specific types of nanoparticles can cause harm. More research is needed.”
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