When aortic walls buckle, the body's main blood pipe forms an ever-growing bulge. To thwart a deadly rupture, a team of Stanford University School of Medicine researchers has found two tiny molecules that may be able to orchestrate an aortic defense. A team led by cardiovascular scientists Philip Tsao, PhD, and Joshua Spin, MD, PhD, identified two microRNAs -- small molecules that usually block proteins from being made -- that work to strengthen the aorta during bulge growth. By tweaking the activity of each molecule, they reduced abdominal aortic aneurysms in mice, which they believe is a promising step toward a new treatment for the disease. Abdominal aortic aneurysms affect thousands of people in the United States each year. The ballooning blood vessel -- which looks more like a snake digesting a bowling ball than a central thoroughfare for oxygenated blood -- is most likely to occur in people over age 65. For smokers, the chances are even greater.