Researchers have taken a huge step towards regrowing organs by successfully creating functional heart tissue out of adult stem cells.

The breakthrough could mean that repairs to damaged hearts could be performed with a patient’s own cells. That reduces the need to find a matching doner and also reduces chances that the body will reject the new tissue.

The new technique isn’t able to rebuild an entire human heart, but rather create a “structural scaffold” within which specialised cardiac cells can function.

Harvard Medical School scientists used adult skin cells and 73 donated human hearts to perform the research, publishing their results in the journal Circulation Research.

The skin cells were treated with messenger RNA (a carrier of genetic information) to revert them back to stem cells. They were then introduced to the donor hearts, which were deemed unsuitable for transplants.

After a few days, the stem cells grew into muscle tissue. The hearts were placed into bioreactor and given a nutrient solution with stressors mimicking the conditions of a living heart.

Roughly two weeks later, the researchers found that the new cardiac muscle tissue was supporting dense regions of cells “that had the appearance of immature cardiac muscle tissue and demonstrated functional contraction in response to electrical stimulation.”

Jacques Guyette, PhD, of the Massachusetts General Hospital Center for Regenerative Medicine (CRM), regenerating a fully-working heart is the team’s goal.

“Regenerating a whole heart is most certainly a long-term goal that is several years away, so we are currently working on engineering a functional myocardial patch that could replace cardiac tissue damaged due a heart attack or heart failure,” he said in a statement.

“Among the next steps that we are pursuing are improving methods to generate even more cardiac cells – recellularizing a whole heart would take tens of billions, optimizing bioreactor-based culture techniques to improve the maturation and function of engineered cardiac tissue, and electronically integrating regenerated tissue to function within the recipient’s heart.”