Heart muscle doesn't regenerate when it's damaged, one reason heart attacks are so debilitating. A dream of researchers is to build new heart muscle using transplanted cardiac stem cells. Scientists at the University of Washington have taken a potentially important step in that direction, using embryonic stem cells as their starting material.
Scientists haven't made much progress obtaining cardiac stem cells that would make the heart cells they would like to see at work. So Charles Murry and his colleagues at the University of Washington have been using embryonic stem cells, which retain the potential to turn into any tissue type in the body.
In their first set of experiments, they coaxed human embryonic stem cells to turn into heart muscle cells, and then put those cells into healthy rats. The human cells took up residence in the rat heart, and started contracting right along with the rat heart muscle cells.
Then they transplanted the cells into rats with hearts damaged by induced heart attacks.
"We found when we went into the damaged heart as opposed to the normal heart, nearly all of the cells that we transplanted in died," Murry said. "And we couldn't overcome this by brute force by just simply putting in more cells. The more we pumped in, the more died."
After some trial and error, Murry and his colleagues found a complex cocktail of chemicals that allowed the human cells to survive and help the damaged rat hearts beat more like normal. The results appear in the current issue of the journal Nature Biotechnology.
It will be years before Murry's approach will be ready for studies in human patients. But several teams around the world are also trying a kind of regenerative therapy using so-called adult stem cells take from a patient's own bone marrow. These cells don't make heart muscle, but they appear to have other benefits.