Heart muscle tissue normally does not regenerate after a heart attack in patients with heart weakness or in children with hereditary malformations, according to the authors of the study published in the July 24 issue of Cell.
Researchers injected the substance called NRG1, a protein, into the peritoneal cavity of live mice after a heart attack, once daily for 12 weeks.
They found "heart regeneration was increased and pumping function (ejection fraction, assessed on echocardiograms) improved as compared with untreated controls," the journal said in a statement.
"To my knowledge, this is the first regenerative therapy that may be applicable in a systemic way," said Bernhard Kuhn of Children's Hospital Boston and Harvard Medical School.
He said that an eventual human treatment could feature daily infusions of NRG1 at a clinic over a period of weeks.
"In principle, there is nothing to preclude this going into the clinic. Based on all the information we have, this is a promising candidate."
Further studies are required to demonstrate safety before such treatment could be tested in human patients, Kuhn stressed.
While "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," Kuhn added.