In an ambitious new gene-hacking study, scientists used CRISPR base editors to shut off the gene that produces low-density lipoprotein (LDL) cholesterol in monkeys — an important step toward someday eradicating a major cause of heart disease in humans.

Researchers from the University of Pennsylvania and the private company Verve Therapeutics developed a one-time gene therapy which, after being injected directly into the monkey's liver, reduced their LDL cholesterol levels by 60 percent in just one week, according to research published Wednesday in the journal Nature.

For reference, LDL is commonly considered "bad" cholesterol compared to high-density lipoprotein (HDL) cholesterol. That's because HDL gets shuttled through the liver to be safely processed, while LDL goes straight into your bloodstream, where it can cause dangerous buildups of plaque that can block your arteries and cause a heart attack or stroke.

In this particular study, the researchers targeted and turned off the gene PCSK9, which encodes a protein of the same name. In some cases, an overactive PCSK9 gene will produce too much of the protein, which interferes with the body's ability to clear LDL cholesterol out of the circulatory system and results in a greater risk of cardiovascular disease. After a week, PCSK9 protein levels in the bloodstream dropped by 90 percent — which explains the 60 percent drop in LDL cholesterol — and it stayed that way for at least ten months after the single injection.

The treatment's path to human trials remains hazy. A Verve Therapeutics spokesperson declined to comment for this story.

But while there's typically a long road of regulatory hurdles to clear before gene therapies that work in animal models might be tested in human patients, if they ever do, the fact that this cholesterol treatment worked so well in primates — rather than, say, mice — is an encouraging sign that human research may be coming soon.