June 23, 2008

New Source of Heart Stem Cells Found

MONDAY, June 23 (HealthDay News) -- Newly-identified stem cells located on the surface of the heart give rise to heart muscle cells, say researchers at Children's Hospital Boston.

They believe the finding may lead to ways to regenerate injured heart tissue.

In previous research, the Children's team found that two types of stem cells (progenitors) marked by activity of the genes Nkx2-5 and IsI1 form many components of the heart. In this new study, the team identified another progenitor, marked by expression of a gene called Wt1, that gives rise to heart muscle cells.

The findings were published online June 22 in the journal Nature.

"There's a lot of interest in finding places to obtain new cardiomyocytes (heart muscle cells), because in heart failure, you lose cardiomyocytes, so the only way to reverse heart failure is to make more of these cells," study senior investigator Dr. William Pu, a pediatric cardiologist, said in a prepared statement.

Although it was known that cells on the surface of the heart (epicardium) give rise to smooth muscle and endothelial cells that line blood vessels, this finding that epicardial cells might turn into cardiomyocytes came as a surprise.

"I couldn't believe it at first, myself," Pu said.

Not only do the progenitor cells marked by Wt1 expression differentiate into cardiomyocytes, they also turn into smooth muscle cells, endothelial cells and fibroblasts (found in connective tissue).

"If you're going to regenerate a tissue, you need to regenerate the whole tissue, not just the cardiomyocytes. This progenitor population contains all the potential to regenerate multiple tissue types within the heart," Pu said.

More information

The U.S. National Heart, Lung, and Blood Institute has more about heart failure.

-- Robert Preidt
SOURCE: Children's Hosptial Boston, news release, June 22, 2008
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