It has long been thought that the heart does not have the ability to repair itself. In other words, when cells turn into fully formed adult heart muscle, they will stop dividing, and cannot replace damaged tissue caused by disease or deformity.
For heart attack patients with heart weakness, people with heart failure or heart disease children with congenital heart defects, their damaged heart muscle tissue normally does not regenerate.
However, researchers from the United States have found a way to repair the damage heart. What they discovered is that heart tissue could be re-grown and heart function improved in mice that were injected a growth factor without using stem cells. Such discovery is indeed a potential breakthrough for human cardiac care.
As published in the July 24, 2009 issue of journal Cell, the researchers from the Children's Hospital Boston and Harvard Medical School injected a substance known as neuregulin1 (NRG1), which is a protein, into the peritoneal cavity of live mice after a heart attack.
The injection was done once daily for a period of 12 weeks. It was found that heart regeneration was increase and pumping function (ejection fraction, assessed on echocardiograms) was improved when comparing to untreated control group.
NRG1 is one of the 4 proteins in the neuregulin family that acts on the EGFR family of receptors. It is essential for the normal development of the nervous system and the heart.
According to the researchers, this is the first regenerative therapy that may be applicable in a systemic way. In principle, human treatment could eventually be carried out with daily infusions of NRG1 at a clinic over a period of weeks.
Nevertheless, further research is still necessary to ensure such therapy is safe before it could be tested to human patients.
With many studies focusing on stem cells, the new finding does suggest that stem cells are not required and that stimulating differentiated cardiomyocytes to proliferate may just be a viable alternative too.