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Microscopic drugs hope for heart patients

Heart patients may in future be injected with microscopic drug-releasing particles that cling to the inside walls of diseased arteries.

Scientists in the US have successfully tested the so-called nanoburrs in rats.

The particles consist of spheres just 60 nanometres across, more than 100 times smaller than a red blood cell.

Each one is coated with tiny protein fragments that allow it to stick to the broken surface of damaged artery walls.

At its core the particle has a drug designed to combat narrowing of blood vessels bound to a chain-like polymer molecule.


Over a period of days, the drug is slowly released and gets to work treating the artery. The time it takes for the drug to be released is controlled by varying the length of the polymer.

Nanoburrs could be employed alongside vascular stents, standard care implants that prop open obstructed arteries, say the researchers.

They could also provide an alternative treatment when it is difficult to use a stent, such as near a fork in an artery.

Professor Robert Langer, one of the scientists from the Massachusetts Institute of Technology in Boston, said: "This is a very exciting example of nano-technology and cell targeting in action that I hope will have broad ramifications."

The same team has previously developed nanoparticles that seek out and destroy cancer tumours.

Nanotechnology incorporates tiny particles at nanometre scales. A nanometre is a billionth of a metre, or a millionth of a millimetre.

The nanoburrs attach themselves to an artery wall structure known as the "basement membrane" which is only exposed when the walls are damaged.

Tests showed that particles injected in the tails of rats reached target areas of damage in the left carotid artery that carries blood to the brain.

The nanoburrs stuck to the damaged walls at twice the rate of non-targeted particles, the researchers reported in the journal Proceedings of the National Academy of Sciences.

They delivered payloads of paclitaxel, a drug that inhibits cell division and helps prevent the growth of artery-clogging scar tissue.

Work is continuing to determine the most effective dose of the drug for treating damaged arteries. The particles may also prove useful for delivering drugs to tumours, say the scientists.