Medically used nanoparticles can damage the DNA of cells without crossing cellular barriers in the body. Published online in Nature Nanotechnology, the study, conducted on cells grown in culture, suggests that the indirect effects of nanoparticles on cells should be considered when evaluating their safety.
Nanoparticles are developed for various drug delivery and imaging applications. Their intended targets include a number of organs normally protected by specialized barriers - such as the blood-brain barrier. Patrick Case and colleagues explored the growing concerns about nanoparticles' ability to infiltrate past such barriers by comparing the effects of direct and indirect exposure of cells to nanoparticles.
The scientists grew a multilayer of human cells in the lab to mimic a specialized protective barrier. They used this barrier to examine the indirect effects of cobalt-chromium nanoparticles - which are generated from wear and tear of bone implants - on the cells that were lying behind this barrier. The amount of DNA damage in the cells behind the protective barrier was similar to the DNA damage caused by direct exposure to the nanoparticles.
The damage was greater than that caused when there is a porous membrane rather than a cell barrier, suggesting that the barrier itself has an important role in the damaging process. Case and colleagues, showed that the nanoparticles did not pass through the barrier to cause the DNA damage, but in fact generated signalling molecules within the barrier cells that were then transmitted to the cells behind the barrier.
These findings suggest that direct and indirect effects of nanoparticles on cells are equally crucial when considering the potential risks of their use in nanomedicine.
Patrick Case (Southmead Hospital, Bristol, UK)
Gevdeep Bhabra (Southmead Hospital, Bristol, UK)Abstract available online.
(C) Nature Nanotechnology press release.
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