Patch Made From Lab-Grown Muscle Can Repair Damaged Hearts

Published in Nature, this study shows that engineered heart tissue can integrate with damaged cardiac muscle and actually help it function again—without causing serious complications.

Heart failure remains one of the biggest global health challenges, with limited options beyond medication, mechanical support, or transplantation. Scientists have long explored ways to repair the heart using stem cell-derived cardiomyocytes, but previous attempts have failed for various reasons: cells didn’t survive long enough, immune rejection, and dangerous arrhythmias sometimes developed. This study was led by Ahmad-Fawad Jebran and colleagues and it took things a step further by using engineered heart muscle (EHM) patches rather than injecting cells individually, and it seems to work much better.

The research focused on rhesus macaques, whose heart physiology is strikingly similar to ours. Instead of injecting heart cells directly into damaged areas, an approach that has often proved inefficient, the team implanted patches of lab-grown heart muscle. These patches, created from induced pluripotent stem cells (iPSCs), included both cardiomyocytes and supportive stromal cells. Importantly, they were designed to integrate closely with the heart’s existing structure, reinforcing weak areas and improving function over six months.

Unlike previous experiments that sometimes triggered arrhythmia, these EHM grafts blended in smoothly with the host heart tissue. The results were encouraging: implanted patches improved heart function, thickened heart walls, and even developed their own blood supply, keeping them alive and working.

The real positive, however, came when the research moved to human trials. A patient with advanced heart failure received an EHM implant, and early signs suggest it’s doing exactly what scientists hoped—helping the heart beat stronger. Lab tests confirmed that the graft had survived and grown new blood vessels, showing it was integrating properly. While it’s still early days, this could be a huge step toward a future where engineered heart muscle offers a real alternative to heart transplants.

That said, in a few cases, some of the implanted cells unexpectedly turned into bone or cartilage-like tissue. Scientists think they can fix this by fine-tuning the way cells are selected before implantation. Another issue is the need for immunosuppressant drugs to prevent the body from rejecting the grafts—something that will need to be addressed before this therapy can become widely available.

Researchers are working to make EHM therapy more effective by creating larger, stronger grafts capable of repairing more extensive heart damage and exploring personalized treatments to minimize immune rejection. Advances in bioengineering, such as 3D bioprinting and more sophisticated vascular scaffolding, could also improve the effectiveness of these patches, bringing them closer to widespread clinical use.

For years, the idea of growing replacement heart tissue in a lab seemed like pure science fiction. Now, with clinical trials already underway, the stuff of sci-fi is threatening to turn into the stuff of Nobel Prize-winning research. Scientists believe we’re on the brink of a revolution in heart disease treatment. If future trials continue to show success, engineered heart muscle therapy could completely change the way we tackle heart failure.