Researchers may have found a way to mend broken hearts. Cells residing in arteries that supply blood to the heart act as cardiac stem cells by producing new muscle tissue, according to a study published in Cell Reports last month.
Our hearts have traditionally been thought of as having zero regenerative potential. “People thought that the same heart you had as a young child, you had as an old man or woman as well,” says Antonis Hatzopoulos from Vanderbilt University. But recent findings demonstrate that new heart muscle cells can be generated at a low rate -- suggesting the tantalizing presence of cardiac stem cells.
To hunt for the source of these elusive cells, the Vanderbilt team focused on cells that line the inner surface of blood vessels -- called endothelial cells. These can give rise to other cell types, such as blood cells, during mammalian development.
By tracking cells in a mouse model, the researchers found that endothelial cells in the coronary arteries generate new cardiac muscle cells in healthy hearts. Two populations of cardiac stem cells in the coronary arteries were identified: a quiescent population in the media (middle) layer and a proliferative population in the adventitia (outer) layer.
That coronary arteries house a cardiac stem cell niche has major implications for the number one killer in the U.S. “Our study suggests that coronary artery disease could lead to heart failure not only by blocking the arteries and causing heart attacks, but also by affecting the way the heart is maintained and regenerated,” Hatzopoulos explains in a news release.
Previously, the team showed that endothelial cells give rise to fibroblasts (connective tissue cells), which generate scar tissue after a heart attack. “It looks like the same endothelial system generates myocytes (muscle cells) during homeostasis and then switches to generate scar tissue after a myocardial infarction,” he explains. “After injury, regeneration turns to fibrosis.”
Figuring out what causes this switch could lead to regenerating heart muscle -- instead of scar tissue -- after heart attacks or as a treatment for conditions like diabetes and high blood pressure.
Images: Nicolas Raymond via Flickr CC BY 2.0 (top), Joe Howell (middle)
