Novel Injection Could Reduce Heart Attack Risk by 40 to 90 Percent, Harvard Researchers Say

Researchers at the Harvard Stem Cell Institute are working on a new type of injection that could lower heart attack risk by 40 to 90 percent.

The team, along with University of Pennsylvania scientists, has taken the "genome-editing" approach to try and reduce cholesterol levels permanently in mice models. The research could pave way for similar treatments in humans.

A heart attack occurs when the heart doesn't get enough oxygen. The condition is the leading cause of death in both men and women in the U.S. Heart attacks are usually caused by atherosclerosis, which occurs when there is too much of cholesterol in the body. Bad fat accumulates along the artery walls. Over time, this fat forms plaque, which is hard on the outside but soft inside. The plaque often breaks and attracts blood platelets. These platelets can clump to form a clot, which narrows blood vessels.

For the present study, researchers focused on a liver gene called PCSK9. Previous research has shown that this gene plays an important role in cholesterol regulation. An interesting observation by independent research groups in France and U.S. is that people with certain mutations in the PCSK9 have increased risk of heart attack while others have lower risk of the heart diseases.

"Our reasoning was that nature has already done the experiment; you have people who have won the genetic lottery," Kiran Musunuru of HSCI. "They are protected from heart attack, and there are no known adverse consequences. So that led us to reason that if we could find a way to replicate this, we could significantly protect people from heart attack."

Researchers then tried to see if they could permanently change the genome to make the "good defects" in the PCSK9 gene. Their work got a boost from the discovery of a technology called CRISPR/Cas9.

CRISPR/Cas9 allows researchers to tweak DNA. It is kind of like creating 'knockout' mice for clinical research.

"What we were thinking was that, with this genome-editing technology, we can do something we couldn't do before: make permanent changes in the genome at the level of the DNA," explained Musunuru, according to a news release. "We can actually go to the source. So the question was whether we can use genome editing to make normal people like people born with the 'good' mutations." The answer, in mice, was yes.

The studies on mice models showed that genome editing worked. The test mice had disruptions in all PCSK9 genes in the liver and even had a 35 to 40 percent reduction in cholesterol, researchers said. In humans, the reduction would translate into a40 to 90 percent lowered heart attack risk.