Injection Reverses Heart-Attack Damage( G rowth factor e...),Health

Growth factor enhances heart regeneration, improves heart function without need for cardiac stem cells

BOSTON, July 23 /PRNewswire-USNewswire/ -- Injured heart tissue normally can't regrow, but researchers at Children's Hospital Boston have now laid the groundwork for regenerating heart tissue after a heart attack, in patients with heart failure, or in children with congenital heart defects. In the July 24 issue of Cell, they show that a growth factor called neuregulin1 (NRG1), which is involved in the initial development of the heart and nervous system, can spur heart-muscle growth and recovery of cardiac function when injected systemically into animals after a heart attack.

After birth, heart-muscle cells (cardiomyocytes) normally withdraw from the cell cycle - meaning they stop dividing and proliferating. But the researchers, led by Bernhard Kuhn, M.D., and Kevin Bersell of the Department of Cardiology at Children's, were able to restart the cell cycle with NRG1, stimulating cardiomyocytes to divide and make copies of themselves -- even though they are not stem cells.

"Although many efforts have focused on stem-cell based strategies, our work suggests that stem cells aren't required and that stimulating differentiated cardiomyocytes to proliferate may be a viable alternative," says Kuhn, the study's senior investigator and a practicing pediatric cardiologist at Children's since 2007.

When the team injected NRG1 into the peritoneal cavity of live mice after a heart attack, once daily for 12 weeks, heart regeneration was increased and pumping function (ejection fraction, assessed on echocardiograms) improved as compared with untreated controls. The NRG1-injected mice also lacked the left-ventricular dilation and cardiac hypertrophy that typify heart failure; both were seen in the controls.<
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