BERKELEY

One of the top suspects behind killer vascular diseases is the victim of mistaken identity, according to researchers from the University of California, Berkeley, who used genetic tracing to help hunt down the real culprit.

Zhenyu Tang (seated at microscope) examines vascular stem cells in culture along with Aijun Wang (left) and Song Li. The UC Berkeley researchers say that these newly discovered stem cells contribute to artery-hardening vascular diseases that can lead to heart attacks and strokes. (Photo courtesy of Song Li)

The guilty party is not the smooth muscle cells within blood vessel walls, which for decades was thought to combine with cholesterol and fat that can clog arteries. Blocked vessels can eventually lead to heart attacks and strokes, which account for one in three deaths in the United States.

Instead, a previously unknown type of stem cell a multipotent vascular stem cell is to blame, and it should now be the focus in the search for new treatments, the scientists report in a new study appearing June 6 in the journal Nature Communications.

For the first time, we are showing evidence that vascular diseases are actually a kind of stem cell disease, said principal investigator Song Li, professor of bioengineering and a researcher at the Berkeley Stem Cell Center. This work should revolutionize therapies for vascular diseases because we now know that stem cells rather than smooth muscle cells are the correct therapeutic target.

The finding that a stem cell population contributes to artery-hardening diseases, such as atherosclerosis, provides a promising new direction for future research, the study authors said.

This is groundbreaking and provocative work, as it challenges existing dogma, said Dr. Deepak Srivastava, who directs cardiovascular and stem cell research at the Gladstone Institutes in San Francisco, and who provided some of the mouse vascular tissues used by the researchers. Targeting the vascular stem cells rather than the existing smooth muscle in the vessel wall might be much more effective in treating vascular disease.

It is generally accepted that the buildup of artery-blocking plaque stems from the bodys immune response to vessel damage caused by low-density lipoproteins, the bad cholesterol many people try to eliminate from their diets. Such damage attracts legions of white blood cells and can spur the formation of fibrous scar tissue that accumulates within the vessel, narrowing the blood flow.

Within the walls of blood vessels are smooth muscle cells and newly discovered vascular stem cells. The stem cells are multipotent and are not only able to differentiate into smooth muscle cells, but also into fat, cartilage and bone cells. UC Berkeley researchers provide evidence that the stem cells are contributing to clogged and hardened arteries. (Song Li illustration)

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The real culprit behind hardened arteries? Stem cells, says landmark study