Nanocontainers to help target artery treatment | Science| In-depth reporting on science and technology | DW | 28.06.2012
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Nanocontainers to help target artery treatment

Millions suffer from circulatory system illnesses that are worsened by atherosclerosis, a narrowing of the arteries. New, targeted treatments using nanotechnology could help them.

Imagine a fleet of tiny disc-shaped containers coursing through your blood, releasing medication at just the right location.

Doctors, chemists and physicists at the universities of Geneva and Basel have been working on this very technology to develop nanocontainers.

Results of an initial study have just been published in the journal Nature Nanotechnology.

The nanocontainers release medication at targeted areas in arteries that have narrowed due to build-up of fatty deposits. This condition is called atherosclerosis and is prevalent in older people.

Atherosclerosis can be a factor in potentially fatal circulatory conditions, such as angina, stroke or heart attack.

It's a leading cause of illness and death in industrial countries - making new treatment options a welcome addition to the medical toolbox.

Novel shape

Bert Müller is a physicist from Berlin, who contributed to the study.

Müller says nanocontainers tend to be spherical or planar in shape. But the ones developed by the Swiss-German team are different.

"Our nanocontainers have a lenticular shape," Müller told DW. "And because the arrangement of molecules [along the outer edge] is less stable, that's where the drug is believed to be released," says Müller.

The lentil-shaped nonocontainers are too tiny to see at about 100 to 200 nanometers wide. Organic chemists from the Geneva team made them out of diaminophospholipids, a material similar to human cell membranes. They have a loose molecular structure that enables the targeted release of the drugs.

lentil-shaped nanocontainer

Nanocontainers use the principle of shear stress for targeted release of medication in narrowed arteries

In addition to their shape, a factor called "shear stress" increases the effectiveness of nanocontainers in releasing medication in a targeted way.

"There's flow within a vessel and the velocity is faster at the center than at the vessel wall [outer edges]," says Müller.

So the increased pressure of blood flowing through a narrowed artery can actually trigger the nanocontainer to deliver its lode.

Nanocontainers that are injected into the bloodstream travel normally through healthy arteries and veins.

"But at the stenose vessels, that is, where it's narrow and the blood flow is increased, they open and release their content," Müller said.

Avoiding negative side-effects

Alberico Catapano, a Milan-based clinical pharmacologist and president of the European Atherosclerosis Society, is intrigued by the concept.

"Theoretically, it's very interesting, and it's one of the ways people can think about delivering drugs in areas where coronary plaque is present," Catapano told DW.

Treatment of atherosclerosis often involves pharmaceutical drugs to control things like high blood pressure or dangerous types of lipids - in particular, cholesterol.

These drugs can have side effects.

"Every drug has a pattern of adverse events related to [it]," says Catapano.

But the use of nanocontainers and their targeted release of medication could help patients avoid certain side effects.

Systemic treatments, such as with nitroglycerin, can make blood vessels widen. This can cause a dangerous drop in blood pressure.

"But having just the targeted release at the [exact location of the] stenose vessels, the narrowed vessels, we can avoid undesired side-effects [in other areas of the body]," Müller says.

Open heart surgery

Open heart surgery is one of the more extreme options to treat advanced atherosclerosis

"This may be a step forward," says Catapano. "But we have to wait and see the results from further research."

Practical use

The best treatment, however, remains prevention.

"The best way to prevent atherosclerosis, or try and delay it, is to have an appropriate lifestyle," says Catapano. This means eating prudent amounts of fatty foods like butter, cheese and meat.

"And then have good exercise - any exercise will do," Catapano says.

The recently published study represents the conceptual stage for development of the nanocontainers.

Next, the team in Basel and Geneva will focus on what kind of molecule to use for the structure of the nanocontainers. They could take an existing material, or develop a novel one that would require new regulatory approval.

Author: Greta Hamann / Sonya Angelica Diehn
Editor: Zulfikar Abbany

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