Thursday, November 5, 2009

New mechanism for nano damage?

New mechanism for nano damage?Posted by Jef Akst
[Entry posted at 5th November 2009 06:00 PM GMT]
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Nanoparticles can damage DNA even in cells that are not directly exposed to them, according to an in vitro study published online today (November 5) in Nature Nanotechnology -- raising further questions about the safety of nanomaterials used in clinical therapies.

Image: Wikimedia commons,
Jerome Walker,Dennis Myts
"DNA damage due to nanoparticles has been described for many types of nanoparticles, but that's done in a primary or direct sense," said Andre Nel, chief of NanoMedicine at the University of California, Los Angeles, who was not involved in the study. "Indirect DNA damage to hazardous nanoparticles is not something that I have seen described before."

Scientists are using nanotechnology to develop delivery systems for drugs and imaging agents, but some studies have suggested these particles may be toxic. Researchers have linked inhalation of nanoparticles or nanotubes to cardoirespiratory disease, for example. Additionally, nanoparticle debris from implants, such as cobalt-chromium (CoCr) alloy particles which can be released from metal-on-metal orthopedic joint replacements, are known to damage human cells in culture.

To further explore the toxicity of CoCr nanoparticles, Charles Patrick Case of the University of Bristol, UK, and his colleagues examined human fibroblast cells that were exposed either directly to the particles or through a cellular barrier. (In a living organism, such a barrier might be the placenta or the lining of the lungs.) They constructed the barrier by growing a thick layer of BeWo cells -- a human cell line often used as a model barrier -- in a porous plastic insert, which they placed above a fibroblast culture. After 24 hours of exposure, the researchers measured the amount of DNA damage in the fibroblasts and found that all cells -- those protected by the BeWo barrier and those directly exposed to the CoCr -- had sustained a significant amount of damage. Parallel experiments with micron-sized particles showed a similar effect.

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