Teams out of the University of Texas Health Science Center at Houston and Ohio University looked at nanoparticles and platelet aggregation:
Carbon nanoparticles – both those unleashed in the air by engine exhaust and the engineered structures thought to have great potential in medical applications – promote blood-clotting, scientists report in an upcoming edition of the British Journal of Pharmacology.
Researchers from The University of Texas Health Science Center at Houston and Ohio University examined the impact of various forms of carbon nanoparticles in a laboratory experiment on human platelets – blood’s principal clotting element – and in a model of carotid artery thrombosis, or blockage, using anesthetized rats.
“We found that some carbon nanoparticles activate human platelets and stimulate them to aggregate, or clump together. We also demonstrate that the same nanoparticles stimulated blockage of the carotid artery in the rat model,” said research team leader Marek Radomski, M.D., Ph.D., of the Center for Vascular Biology at the Brown Foundation Institute of Molecular Medicine (IMM) at the UT Health Science Center.
C60, a spherical carbon molecule also known as a fullerene or “bucky ball,” was the exception, showing no effect on human platelet aggregation and very little effect on rat thrombosis…
In a paper posted online ahead of publication last month, the team compared the impact of standard urban particulate matter, mixed carbon nanoparticles, “bucky balls,” single-wall carbon nanotubes, and multiple wall carbon nanotubes on human platelet clumping and thrombosis in rats.
In both experiments, the mixed carbon nanoparticles had the most impact, provoking the greatest degree of platelet aggregation and the most dramatic reduction of carotid blood flow in the rats. The single-wall carbon nanotubes ranked second, the multiple wall nanotubes third and the standard urban particulate matter fourth in both experiments.
These four types of nanoparticles also were shown to activate a receptor on platelets that is vital to their aggregation – the glycoprotein integrin receptor. This seems to be the underlying mechanism for the nanoparticle’s effects, the researchers note, but each nanoparticle employed a different molecular pathway to activate the receptor.
Bucky balls had virtually no effect. Nanotubes appear to mimic molecular bridges involved in platelet interactions while the bucky balls do not. This gives the spherical, less adhesive bucky balls a potential advantage in the design of nanopharmaceutical devices for targeted drug delivery or imaging systems, the researchers note.
The impact of mixed carbon nanotubes and standard urban particulates suggests a risk of thrombosis from airborne pollution, in addition to the risk of atherosclerosis and heart attack.
The press release…