By mimicking the behavior of platelets, a new drug delivery system sends clot-dissolving drugs directly to obstructed blood vessels.
Blood clots are bad news. These masses of blood cells can grow big enough to choke off veins and arteries, preventing oxygen from flowing to critical organs, ScienceNOW explains.
Platelets circulate in the blood and stop bleeding by forming clots. They naturally gravitate toward blocked vessels by sensing changes in blood flow; they’re attracted to high fluid shear stress.
So, a team led by Donald Ingber of Harvard’s Wyss Institute for Biologically Inspired Engineering took advantage of that characteristic.
- They took a clump of nanoparticles about 100 nanometers wide and coated them with a clot-dissolving drug called tissue plasminogen activator (tPA).
- They created a drug delivery system that’s attracted to high fluid shear stress in blood vessels, just like platelets. These carry the drugs directly to narrowed blood vessels.
- Then they fall apart to release the tPA-coated nanoparticles when the stress reaches a certain point (pictured above).
- The biodegradable particles are eventually broken down by the body.
- They tested their new delivery system on mice with blood clots, and the system restored normal blood flow quickly.
And since the nanoparticles deposit a small amount directly on the clot, it used less tPA than what’s normally required – good news since tPA can lead to unwanted side effects, such as excessive bleeding, when administered into the blood without this sort of delivery system.
Pictured right, a blocked mouse artery with fluorescent nanoparticles accumulating around it. Watch a video of the clot-busting action.
The particles could be used to deliver essentially any drug – an anti-inflammatory to a specific spot where inflammation was occurring, for example, Ingber says.
The nanoparticles could also be used as a diagnostic tool to seek out blockages that may need to be removed surgically, since places where the nanoparticles wind up are easier to spot with ultrasound.
The work was published in Science last week.
Image: Wyss Institute for Biologically Inspired Engineering