Some find embryonic stem cell research heartbreaking.

For pathology professors Michael Laflamme and Chuck Murry, it’s what could keep hearts beating.

The researchers are creating heart muscle tissue from human embryonic stem cells and testing it in rat hearts that have suffered heart attacks. It’s one of the first projects to show that these types of cells could be useful in preventing heart disease, the country’s number one killer.

At this point, the method would be used on someone who had a heart attack to repair his or her muscle tissue, which would improve function and quality of life, said Tony Blau, a professor of medicine and hematology and co-director of the UW Institute for Stem Cell and Regenerative Medicine.

“The significance of it is we found a way to grow back heart muscle,” Murry said. “People die from heart attacks from the amount of heart muscle they lose after [an] attack, so it seems like we’re pretty close to making a translational step.”

Michael Rubart, a professor of pediatrics at Indiana University who wrote a review paper of the project, said this research brings scientists one step closer to achieving lasting improvement in the heart’s function, but the researchers still have some work to do.

“There are still many hurdles to take before this technique can be used clinically on a routine base,” he said. “For example, … protocols to enhance the purity of the donor cell population will be needed to minimize the risk of tumor formation. All this may take years before the first clinical trial can be launched.”

Scientists plan to use stem cells for spinal cord repairs in humans by the end of 2008. Using them for heart repair could happen in three to five years, Murry said.

The project began in 2002 when Laflamme and Murry struggled to keep embryonic stem cells alive in damaged rat hearts, which as hostile environments, are often rejected by healthy cells. Maintaining the stem cells as heart muscle cells was difficult, Laflamme said, because of their ability to become any type of cell.

Harvard researchers followed Laflamme and Murry’s model to derive stem cells from human skin.

“We were thrilled to see that our work was put into use so quickly and, in turn, we’re very encouraged that the cells they were able to make can very readily make heart muscle cells,” Murry said. “We’re hoping to have this running in our lab in the next calendar year.”

Yet, with a rate of 400 beats per minute and a size 250 times smaller, rat hearts are quite different from their human counterparts. The next step, Murry said, is to test the method in larger animals like dogs or primates, which will help the team overcome problems more likely to be seen in a person.

In this project, researchers want to grow tissue with blood cells and find if the heart beats while these stem cells are in it.

“At present, this is our most promising avenue of taking stem cells and putting them into a patient someday,” Blau said. “Chuck and Mike are world leaders in their area.”

[Reach columnist Meghan Peters at news@thedaily.washington.edu.]