A study recently has proved that stem cells grown from patients’ own cardiac tissue can heal damage once thought to be permanent after a heart attack. The cells, called cardiosphere-derived stem cells, regrew damaged heart muscles and reversed scarring one year later, the authors say.

The stem cells were implanted within five weeks after the patients had suffered heart attacks. Doctors removed heart tissue, about the size of half a raisin, using a minimally invasive procedure that involved a thin needle threaded through the veins. After cultivating the stem cells from the tissue, doctors reinserted them using a second minimally invasive procedure. Patients got 12.5 million cells to 25 million cells

A year after the procedure, six patients in the stem cell group had serious side effects, including a heart attack, chest pain, a coronary bypass, implantation of a defibrillator, and two other events unrelated to the heart. One of patient’s side effects were possibly linked to the treatment, the study found.

According to the report published in ‘the medical journal Lancet’, in a trial of 25 heart-attack patients, 17 who got the stem cell treatment showed a 50 percent reduction in cardiac scar tissue compared with no improvement for the eight who received standard care. The results, from the first of three sets of clinical trials generally needed for regulatory approval.

The study, by researchers from Cedars-Sinai Heart Institute in Los Angeles and Johns Hopkins University in Baltimore, tested the approach in patients who recently suffered a heart attack, with the goal that repairing the damage might help stave off failure. While patients getting the stem cells showed no more improvement in heart function than those who didn’t get the experimental therapy, the theory is that new tissue regenerated by the stem cells can strengthen the heart, said Eduardo Marban, the study’s lead author.

While the main goal of the trial was to examine the safety of the procedure, the decrease in scar tissue in those treated merits a larger study that focuses on broader clinical outcomes, researchers said in the paper.

Marban, who invented the stem cell treatment, said the while it would not replace bypass surgery or angioplasty, “it might be useful in treating ‘irreversible’ injury that may persist after those procedures.”

As a rough estimate, he said that if larger, phase 2 trials were successful; the treatment might be available to the general public by about 2016.