Nanoparticles could replace stents for heart patients

Posted by Emma Woollacott

Patients with heart disease could soon be treated without stents, thanks to tiny nanoparticles that can home in on damaged tissue and release drugs.

The particles have been dubbed 'nanoburrs' because they're coated with protein fragments that allow them to stick to target proteins. They can  drip-feed drugs over several days.

The nanoparticles are targeted at the basement membrane, which lines the arterial walls and is only exposed when they are damaged. The researchers hope the particles could either complement or replace stents.

"This is a very exciting example of nanotechnology and cell targeting in action that I hope will have broad ramifications," says MIT Institute Professor Robert Langer.

The 60-nanometer particles have three layers: an inner core containing the drug and a polymer chain called PLA; a middle layer of soybean lecithin, a fatty material; and an outer coating of a polymer which protects the particle as it travels through the bloodstream.

The drug is released when it detaches from the PLA polymer chain, which occurs gradually through a reaction called ester hydrolysis. The longer the polymer chain, the longer this takes, so the researchers can control the timing. So far, they've achieved drug release over 12 days in tests in cultured cells.

In tests in rats, the researchers showed that the nanoburrs can be injected intravenously into the tail and still reach their intended target.

The particles may also prove useful in delivering drugs to tumors.

"This technology could have broad applications across other important diseases, including cancer and inflammatory diseases where vascular permeability or vascular damage is commonly observed," says Omid Farokhzad, associate professor at Harvard Medical School.

The development is described in the Proceedings of the National Academy of Sciences.