Cardiac stem cells come closer to clinic

The laboratory of MDA grantee Kenneth Chien at the University of California-San Diego announced in a recent issue of Nature that its researchers have discovered in the hearts of mice, rats and humans a new type of stem cell that can become a mature cardiac cell.

Chien says these are the actual cells that form the heart during fetal development and that his group has identified them by the presence of a protein called islet-1.

Muscle-specific stem cells (known as myoblasts or myogenic precursor cells) have long been known to populate skeletal muscle tissue throughout life and to move in when repairs are needed. But until recently, it was believed that the heart didn’t contain such cells after birth.

Although the number of islet-1-bearing cells, dubbed cardioblasts by the researchers, is small (500 to 600 in young rats), they can be coaxed to multiply into millions in the lab.

“The findings are significant both as a new model to study human heart disease and to develop potential treatments,” Chien says.

In a separate study, researchers at the University of Louisville (Ky.) and New York Medical College in Valhalla treated damaged rat hearts with cardiac stem cells (different cells from Chien’s) delivered into a major blood vessel. The rat hearts, damaged by a blockage in a major artery, showed significant benefit from the injected cells.

In the March 8 issue of Proceedings of the National Academy of Sciences, the researchers write, “This study demonstrates that CSCs [cardiac stem cells] are effective when delivered in a clinically relevant manner.”

Because people with genetic disorders would have cardiac stem cells with genetic abnormalities, their own cells would have to undergo genetic modification before being reinjected in any future treatment scenario. Or, donor cells could be used.