Oct. 12 (HealthDay News) -- U.S. researchers have achieved a first step toward growing a living "heart patch" to repair damage from heart disease.

Using mouse embryonic stem cells, Duke University bioengineers performed a series of lab experiments that mimicked the way embryonic stem cells develop into heart muscle.

The researchers used a special mold they created to make a 3-D "patch" made of heart muscle cells called cardiomyocytes. The mold had features that enabled the researchers to control the direction and orientation of the growing cells.

The newly created tissue displayed two critical features of heart muscle cells -- the ability to contract and to conduct electrical impulses, the study authors explained in a Duke University news release.

The results were scheduled to be presented at the Biomedical Engineering Society's annual scientific sessions, held Oct. 7 to 10 in Pittsburgh.

"While we were able to grow heart muscle cells that were able to contract with strength and carry electric impulses quickly, there are many other factors that need to be considered," Nenad Bursac, an assistant professor at Duke's Pratt School of Engineering, said in the news release.

The rate of heart muscle cell development is just one area that requires further research.

"Human cardiomyocytes tend to grow a lot slower than those of mice," Bursac said. "Since it takes nine months for the human heart to complete development, we need to find a way to get the cells to grow faster while maintaining the same essential properties of native cells."

SOURCE: Duke University, news release, Oct. 10, 2009