Microscopic stealth drones that seek out and repair areas of artery damage could be the future of new treatments for heart disease and stroke.
Scientists at the Laboratory of Nanomedicine and Biomaterials at Brigham and Women's Hospital in Boston, US, have carried out successful tests of the nanoparticles in mice and hope soon to conduct the first patient trials.
Each nanoparticle, made from a biodegradable polymer, is 1,000 times smaller than the tip of a human hair. They are designed to latch onto atherosclerotic plaques - hard deposits made from accumulated fat, cholesterol and calcium that build up on the walls of arteries and are prone to rupture, producing dangerous clots.
They are engineered to carry pieces of an "inflammatory-resolving" protein called Annexin A1 which the body uses to quell inflammation and trigger healing.
In mice injected with the nanoparticles, significant improvements were seen, including reduced inflammation and a thickening of collagen layers in atherosclerotic placques that prevented them rupturing. Plaques were shrunk in size, and cleared of dead cells accumulating within them. Similar changes were not seen when the Annexin A1 was administered freely without being attached to the targeting nanoparticles, or when "empty" nanoparticles were used.
The scientists also observed a reduction in reactive oxygen species (ROS), highly destructive molecules that damage cells.
Lead researcher Dr Omid Farokhzad said: "Years of research and collaboration have culminated in our ability to use nanotechnology to resolve inflammation, remodel and stabilise plaques in a model of advanced atherosclerosis.
"The inflammation resolving targeted nanoparticles have shown exciting potential not only for the potential treatment of atherosclerosis as described here, but also other therapeutic areas including wound repair, for example"
The scientists, whose results appeared in the journal Science Translational Medicine, cautioned that although mice developed human-like atherosclerotic plaques they did not suffer heart attacks.
Because other applications of the nanoparticles have already been tested on humans, progress to clinical trials is not expected to take long.
"I'm optimistic that with additional animal validation we will also consider the human testing of the inflammation-resolving targeted nanoparticles for a myriad of unmet medical needs," Dr Farokhzad said.
For the human trials, the team plans to fine tune the particles to optimise drug delivery and to package them with more powerful anti-inflammatory drugs.