Scientists found a way to use the body's natural clot-producing mechanisms to deliver targeted medicine in a study that may have implications for treatments of heart attacks and stroke.
Obstructions in blood vessels lead to a force called shear stress, attracting platelets that form blood clots. Researchers designed a drug-delivery method that activates only in those conditions, potentially enabling more targeted delivery of clot- busting medicines in lower doses that can be given before a patient gets to a hospital, they wrote in a paper published online today in the journal Science.
Heart disease and stroke are some of the leading causes of death in the U.S., with about 785,000 Americans a year having their first coronary attack, according to the Centers for Disease Control and Prevention. Medicines designed to eliminate clots in those events often need to be given in a hospital and in doses that can lead to side effects such as excessive bleeding, limiting the number of patients who can take them, said Donald Ingber, a professor of vascular biology at Harvard Medical School in Boston and an author of the study.
"People have wanted to figure out targeting, but they haven't come up with a way," Ingber, who is also director of the Wyss Institute for Biologically Inspired Engineering at Harvard, said in a telephone interview. "We knew platelets can somehow go to narrowing vessels, and thought if biology can do it, somehow we can do it."
The delivery system, called shear-activated nanotherapeutics, is a bundle of tiny drug-coated particles that travel together until they reach the obstruction, when the shear stress causes them to break apart and attack clots. The study, done in mice, used an approved clot-targeting therapy called tissue plasminogen activator, or tPA, and found that the system allowed for use of less than one-fiftieth the normal dose to dissolve clots, Ingber said.
The technique is years away from testing in humans, and the scientists have plans to improve some of the chemistry involved, Ingber said. While the technology isn't backed by a company, there are discussions about it, he said.
"This is a great startup opportunity because the same delivery system could be used to deliver any drug," Ingber said, citing anti-inflammatories for atherosclerotic plaques, as well as therapies for sickle cell anemia and coronary spasm. "This clot-busting application alone -- the diseases it targets in myocardial infarction, pulmonary embolism and stroke -- those are the big killers."