A Shotgun for Blood Clots

Think of it as Liquid-Plumr for the circulatory system. Researchers have designed a clump of tiny particles that rides the current of the bloodstream, seeks out life-threatening blood clots, and obliterates them. The approach works in mice and could soon move on to human trials.

Blood clots are bad news for the brain, heart, and other organs. These masses of blood cells can grow big enough to choke off veins and arteries, preventing oxygen from flowing to critical organs. One of the chief obstacles to dealing with blood clots is finding where they have lodged in the body. Even if doctors locate clots, they're hard to get rid of. Doctors often prescribe blood thinners that slow down the time it takes a clot to form, but such medication can also cause excessive bleeding. Another method is stenting, a procedure in which a flexible wire or tube is used to reopen a vessel. Patients recover quickly but often spend at least 1 night in the hospital.

Looking for a better approach, biomedical engineer Donald Ingber of Harvard University and colleagues turned to nanoparticles. Modeled after platelets—cells that circulate in the blood and help stop bleeding by forming clots—the nanoparticles are less than 100 nm wide and made of synthetic polymers stuck together like a ball of wet sand. Like platelets, clumps of the particles flow freely in the blood and gravitate toward blocked vessels by sensing a change in blood flow. Once there, they break apart into individual particles that stick to the clot, releasing a drug called tissue plasminogen activator (tPA) that dissolves it.

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