During heart month last year, scientists revealed that the beating heart inside newborn mice can regenerate itself after an injury . And they’ve been looking for ways to harvest this self-regeneration for adult human hearts. Stem cells, surprisingly, were not involved.

Now, another team of researchers have used stem cells gathered from patients’ own hearts to heal scarring caused by their heart attack.

Within a year, the amount of scar tissue was halved and there was an increase in new heart muscle, according to a small safety trial with 25 heart attack victims.

When blood flow to the heart is blocked, it’s starved of oxygen. Dead muscle is replaced with scar tissue – reducing the organ’s ability to pump blood around the body.

To replace scar tissue with beating muscle, a team led by Eduardo Marbán of Cedars-Sinai Heart Institute started with stem cells – called cardiosphere-derived cells – taken from a patient’s own heart. Time explains:

The heart has a natural ability to fix minor defects by regenerating new muscle cells to replace dying ones. About 1% to 2% of heart cells die each year, and are replaced this way. This process can’t come close to regenerating the one-third of heart muscle that is typically affected by a heart attack, however, so Marban and his team decided to give the process a boost.

Within 5 weeks of the attack, a tube was inserted into a vein in the neck and pushed down towards the heart. A small sample of heart tissue (the size of a raisin) was taken by threading a thin needle through the veins. Stem cells were isolated from this sample in a lab and then cultivated. About 12 million to 25 million of these new stem cells were put back into the arteries surrounding the heart.

Before the treatment, BBC reports, scar tissue accounted for an average of 24% of their left ventricle, a major chamber of the heart. It went down to 16% after half a year and 12% after a year.

"We dissolved scar and replaced it with living heart muscle,” Marban says. “Such 'therapeutic regeneration' has long been the holy grail of cell therapy.”

However, there was no increase in the heart's ability to pump or the amount of blood flowing out of the heart.

“If we can regenerate the whole heart, then the patient would be completely normal,” Marban says. “We haven’t fulfilled that yet, but we’ve gotten rid of half of the injury, and that’s a good start.”

The tech is being developed by LA-based Capricor Inc., founded by Marban. The company will further test it in 200 patients for the second of three required trials, and if successful, the treatment might be available by 2016.

The work was published in The Lancet today.

Image by searchclinicaltrials via Flickr

This post was originally published on Smartplanet.com